9 research outputs found
Hubungan Tingkat Pendidikan dengan Kepatuhan Berobat Penderita TB Paru di Wilayah Kabupaten Lamongan pada Januari 2016 – Desember 2018
No full textAbstrakLatar Belakang: Indonesia menduduki peringkat ke-3 jumlah penderita Tuberkulosis (TB) terbanyak di dunia, serta angka kematian TB setiap tahunnya sekitar 20% dari jumlah penderita TB baru. Pengobatan pada TB paru rentan untuk terjadi putus berobat (drop out) yang bisa disebabkan oleh beberapa faktor, salah satunya adalah kepatuhan dalam berobat. Ketidakpatuhan terhadap pengobatan dapat disebabkan oleh berbagai faktor meliputi faktor predisposisi (Usia, jenis kelamin, tingkat pendidikan, dan pekerjaan), faktor pendorong (efek dari OAT), dan faktor penguat (dukungan keluarga, petugas kesehatan dan pelayanan kesehatan).Tujuan: Studi ini dilakukan untuk mengetahui adanya hubungan antara tingkat pendidikan dengan kepatuhan berobat penderita TB paru di Wilayah Kabupaten Lamongan.Metode: Studi ini menggunakan desain cross sectional dengan teknik pengambilan sampel yaitu simple random sampling pada 55 pasien TB paru drop out serta 55 pasien TB paru sembuh dari tahun 2016-2018 di Wilayah Kabupaten Lamongan. Pengambilan data menggunakan rekam medis dari Dinas Kesehatan.Hasil: Hasil uji statistik menggunakan Koefisien Kontingensi terhadap hubungan tingkat pendidikan dan kepatuhan berobat pada pasien TB menunjukkan nilai yang signifikan p: 0,026 (p<0,05)Kesimpulan: Hasil penelitian ini menunjukkan adanya hubungan antara tingkat pendidikan dengan kepatuhan berobat penderita TB paru.Kata Kunci : Tuberkulosis paru, Tingkat pendidikan, Kepatuhan berobat Abstract: Background: Indonesia ranks 3rd in the number of tuberculosis (TB) cases in the world, and the annual TB mortality rate is around 20% of the number of new TB cases. Treatment of pulmonary TB is prone to drop out, which can be caused by several factors, one of which is adherence to treatment. Non-adherence to treatment can be caused by various factors, including predisposing factors (age, gender, education level, and occupation), driving factors (effects of OAT), and reinforcing factors (family support, health workers and health services).Aim: This study was conducted to determine the relationship between education level and compliance with pulmonary tuberculosis treatment in Lamongan Regency.Methods: This study used a cross sectional design with a simple random sampling technique of 55 pulmonary TB patients dropping out and 55 pulmonary TB patients recovering from 2016-2018 in Lamongan Regency. Retrieving data using medical records from the Health Office.Results: The results of statistical tests using the Contingency Coefficient on the relationship between education level and treatment compliance in TB patients showed a significant value of p: 0.026 (p <0.05).Conclusion: The results of this study indicate a relationship between the level of education and adherence to treatment of pulmonary TB patients
ANALISIS KUALITAS PELAYANAN DENGAN METODE SERVICE QUALITY (SERVQUAL) DAN IMPORTANCE PERFORMANCE ANALYSIS (IPA) PADA PT. MEDIA PURNA ENGINEERING
No full textPT. Media Purna Engineering is a company engaged in the field of mechanical maintenance services rotating, hydraulic systems, construction, and piping. PT. Media Purna Engineering has never conducted a measurement of the level of satisfaction of its partner companies so that in improving the quality of service and in overcoming the complaints have not been done properly. The purpose of this study is to improve the quality of service to the satisfaction of partner companies namely PT. Krakatau Steel (Persero) Tbk for the services provided. The research method used is the method of Service Quality (Servqual) and Importance Performance Analysis (IPA) to measure the level of satisfaction and quality of services provided .. Based on research results indicate that the quality of service PT. Media Purna Engineering is good, but there are 1 service quality attribute that still need to be improved or developed from 25 attribute of service quality, that is at the 15th attribute about speed in giving solution. Recommendations for improvement include the introduction of the work area, new workers should always be supervised and supervised, schedule training, constraints please quickly inform Lieder or Supervisor to be quick in providing solutions to overcome them
Estudo das propriedades estruturais, eletrônicas e ópticas do tetraborato de magnésio (MgB4O7) e do defeito antissítio em compostos Bi12MO20 (M=Ge,Si,Ti) utilizando cálculos de primeiros princípios
No full textThis work represents a theoretical study, based on density functional theory (DFT), on
structural, electronic and optical properties of magnesium tetraborate (MBO, MgB 4 O 7 )
compound and of antisite Bi M O 4 defect in Bi 12 MO 20 (BMO, M=Ge, Si, Ti) compounds.
All calculations have been realized by linear augmented plane wave (LAPW) method
implemented in Wien2k computer code. The relaxation of atomic positions and lattice
parameters has been performed using LDA (MBO) and PBE-GGA (BMO) exchange-
correlation (XC) functional. Electronic structure, optical properties and chemical bonds
were investigated using the semi-local XC potential of Tran and Blaha (TB-mBJ), which
significantly improved the band gap description and optical properties of studied systems.
The thesis is divided in two parts. The first refers to study of magnesium tetraborate
in pure form. Electronic structure calculations predicted a 9.58 eV band gap value, quite
close to the value determined in the similar compounds. The electronic structure around
the band gap is found to be dominated by the O 2p-states and 2p-states of the boron
ion with trigonal coordination with neighbouring O‘s. Optical properties were analysed
in terms of complex dielectric tensor which imaginary part is directly proportional to
the optical absorption spectra. The latter is found to exhibit two prominent peaks. The
lower energy peak originates from electron transitions within the trigonal B−O 3 structural
group. Refractive index, reflectivity, extinction coefficient and energy loss were analysed
in ultraviolet range (up to 40 eV) and all calculated optical properties are found to be
anisotropic.
The second part presents a theoretical study upon the antisite defect Bi M O 4 in sillenites
compounds, which consists of wrong occupation of the M site by the Bi ion. Calculations
were performed firstly for the pure compounds. The crystal structure has been computatio-
nally optimized and the band gaps found to be 3.39 eV, 3.35 eV and 3.37 eV for the BGO,
BSO and BTO respectively. These values are in very good agreement with experimental
data. Defects were investigated in q=-1,0,1 charge states. Electronic structure calculations
demonstrated that the antisite defect introduces an energy band inside the gap formed by
O 2p- and 6s- states of Bi M ion. This band occupation is directly related to the defect
charge state. The neutral defect presents a semi populated band, the positively defect adonor band and the negatively defect an acceptor band. The Bader analysis confirmed that
the electron added or removed from the host system is always localised in the area of the
defect. The analysis of the defect formation energies demonstrated that the neutral defect
is energetically favourable, and thus dominates the lowest thermal state of the sillenites
(also called colour state). On the other hand, the charged defects are predominant in
the so-called transparent thermal state of the sillenites. From the results, it was possible
to associate the presence of the antisite defect with important properties observed in
the BMO crystals, such as: (1) explanation of the charge mobility required to produce
the photorefractive effect; (2) reversible transitions between the thermal states and (3)
photocromic effect in sillenites.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESNesse trabalho foi realizado um estudo te´orico, baseado na Teoria do Funcional da
Densidade (DFT), das propriedades estruturais, eletrˆonicas e ´opticas do tetraborato de
magn´esio (MgB 4 O 7 ) e um estudo do defeito tipo antiss´ıtio Bi M O 4 em cristais do estruturas
silenitas Bi 12 MO 20 (BMO, onde M=Ge, Si e Ti).
As otimiza¸c˜oes das posi¸c˜oes atˆomicas e parˆametros de rede foram realizadas para todos
os sistemas utilizando o funcional LDA e GGA-PBE para o MgB 4 O 7 e BMO’s, respecti-
vamente. As estruturas eletrˆonicas e propriedades ´opticas do sistemas estudados foram
calculadas utilizando o m´etodo LAPW implementado no c´odigo computacional WIEN2k.
Os efeitos de correla¸c˜ao e troca, das estruturas eletrˆonicas e ´opticas, foram simulados
pelo recentemente desenvolvido potencial TB-mBJ, que foi mostrado ser adequado para
tratamento de sistemas que possuem gap.
Essa tese foi dividida em duas partes. A primeira parte refere-se ao estudo do tetraborato
de magn´esio puro. Os c´alculos da estrutura eletrˆonica resultaram em um valor do gap
de 9,58 eV, bem pr´oximo ao esperado (comparando a compostos similares). O topo da
banda de valˆencia ´e dominado por estados 2p dos oxigˆenios, enquanto o fundo da banda
de condu¸c˜ao consiste predominantemente de estados 2p do boro de coordena¸c˜ao trigonal
com os oxigˆenios vizinhos (BO 3 ). As caracter´ısticas propriedades ´opticas foram calculadas
a partir do tensor diel´etrico complexo, cuja parte imagin´aria ´e diretamente proporcional
ao espectro de absor¸c˜ao ´optica verificou-se que a borda de absor¸c˜ao ´optica ´e originada
por poss´ıveis transi¸c˜oes eletrˆonicas entre os ´ıons que formam a estrutura trigonal BO 3 . O
espectro de absor¸c˜ao tamb´em indicou um car´ater anisotr´opico para o composto. O ´ındice
de refra¸c˜ao, coeficiente de extin¸c˜ao, refletividade e a perda de energia de el´etrons foram
calculados na regi˜ao ultravioleta at´e 40 eV. A segunda parte refere-se ao estudo do defeito
tipo antiss´ıtio em silenitas. Os cristais foram estudados nas formas puras e com a presen¸ca
de um ´atomo de Bi ocupando o s´ıtio do ´atomo M (Bi M O 4 ). Os defeitos foram investigados
nos estados de carga q=−1, 0, +1. Os band gaps dos BMO’s puros foram determinados
com os valores de 3,39 eV para BGO, 3,35 eV para BSO e 3,37 eV para o BTO.
Atrav´es das an´alises das densidades de estados eletrˆonicos foi confirmado que o defeito
antiss´ıtio introduz uma banda de energia situada dentro do intervalo de energias proibidas,bandgap, formada por estados 2p dos oxigˆenios e 6s do defeito Bi M . A popula¸c˜ao eletrˆonica
dessa banda est´a diretamente relacionada ao estado de carga. O defeito neutro (Bi
0
M
)
introduz uma banda semi populada, o defeito carregado negativamente (Bi
−1
M
) uma banda
doadora e o defeito carregado positivamente (Bi
+1
M
) uma banda aceitadora. A an´alise
das liga¸c˜oes qu´ımicas confirmou que a adi¸c˜ao (ou retirada) de um el´etron do sistema
sempre ocorre na banda associada ao defeito. A an´alise da energia de forma¸c˜ao de defeito
constatou que o defeito neutro ´e o energeticamente favor´avel, dominando assim o estado de
menor energia (tamb´em chamado de estado colorido). A partir dos resultados, tamb´em foi
poss´ıvel associar a presen¸ca do defeito antiss´ıtio como geradora de importantes propriedades
observadas nos cristais BMO’s, tais como: a mobilidade de carga que ocasiona o efeito
fotorrefrativo; a compreens˜ao das transi¸c˜oes revers´ıveis entre estados t´ermicos e o efeito
fotocrˆomico
Caracteriza??o cin?tica e bioqu?mica da enzima inosina monofosfato desidrogenase (EC 1.1.1.205) de Mycobacterium tuberculosis como alvo para o desenvolvimento de inibidores
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Previous issue date: 2013-09-11Tuberculosis (TB) remains a leading infectious killer and its causative agent, Mycobacterium tuberculosis, infects one third of the world population. Despite 50 years of available drug treatments, TB continues to cause considerable mortality worldwide. The TBHIV co-infection and the emergence of multidrug and extensively-resistant TB have provided a very alarming challenge to global health and led us to focus on the research for new and more effective therapeutics against the disease. Advances in the identification of new TB drug targets have been driven by the availability of the genome sequence of M. tuberculosis H37Rv, and include elucidation of the role played by proteins of essential biochemical pathways for mycobacterial growth. Inosine Monophosphate Dehydrogenase (IMPDH, EC 1.1.1.205) catalyzes the penultimate and rate-limiting step in guanine nucleotide biosynthesis, the oxidation of inosine 5 -monophosphate (IMP) to xanthosine 5 - monophosphate (XMP), with concomitant reduction of nicotinamide adenine dinucleotide (NAD+) to NADH. This reaction controls the guanine nucleotide pool and IMPDH inhibitors are used as immunosuppresive, anticancer, and antiviral agents. Recently, IMPDH from M. tuberculosis (MtIMPDH) has gained attention as a promising anti-mycobacterial target, associated with a number of distinct inhibitor scaffolds. In the present work, the guaB2- encoded MtIMPDH has been cloned, expressed and purified to homogeneity. The recombinant MtIMPDH has a subunit molecular weight of 54,775 Da and Inductively-Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Flame Atomic Absorption Spectroscopy (FAAS) identified a K+ ion per subunit. Glutaraldehyde cross-linking analysis suggests that MtIMPDH predominates as a tetramer. Steady-state kinetics showed that MtIMPDH optimal activity is dependent on the presence of a monovalent cation, mainly K+. Initial velocity and product inhibition patterns suggested a steady-state ordered Bi Bi kinetic mechanism in which IMP binds first followed by NAD+, and hydride transfer is not the ratelimiting step in the MtIMPDH catalyzed reaction. In addition, NAD+ substrate inhibition implies that product release is ordered, with NADH released first. The pH-rate profile indicated one deprotonated group essential for catalysis and that groups with pK values of 7.5 and 9.0 are important for NAD+ binding. The data presented here are discussed in light of the kinetic and structural information available for IMPDHs investigated to date and should inform us on how to better design inhibitors targeting this enzyme. Additionaly, a vital part of drug development is the identification of gene products that are critical for bacterial growth and survival. In this regard, we have performed site-directed mutagenesis by gene replacement in order to evaluate the importance of the guaB2 gene for mycobacteria growth. Our results suggest that this gene is essential for M. tuberculosis H37Rv in vitro growth, and the confirmation of gene essentiality will point out the guaB2-encoded IMPDH as a potential drug target. Data resulting from enzyme s characterization and gene replacement were the starting point for MtIMPDH inhibitors planning, selection and testing. A compound was identified as promising lead molecule, with Ki values in nanomolar range and it was characterized as noncompetitive and uncompetitive inhibitor towards MtIMPDH substrates NAD+ and IMP, respectively. MtIMPDH characterization and results on primary inhibitors identification are crucial step towards a potential novel drug development for TB treatment. Altogether, these data may be useful for a better understanding about the biology of M. tuberculosis and as a framework on which to base efforts towards the development of efficient therapeutic strategies, aiming TB control.A tuberculose (TB) permanece entre as principais causas de morte por doen?as infectocontagiosas e estima-se que um ter?o da popula??o mundial esteja infectada pelo Mycobacterium tuberculosis. Apesar de existirem tratamentos dispon?veis h? mais de 50 anos, a TB ? respons?vel por causar altas taxas de mortalidade em todo o mundo. A coinfec??o com o HIV e a emerg?ncia de TB resistente a m?ltiplas drogas representam um desafio ? sa?de p?blica e t?m estimulado a pesquisa por novos e mais efetivos agentes terap?uticos contra a doen?a. Avan?os na identifica??o de novos alvos para drogas contra a TB t?m sido poss?veis gra?as ao sequenciamento do genoma do M. tuberculosis H37Rv e incluem a elucida??o da fun??o de prote?nas envolvidas em rotas bioqu?micas essenciais para o crescimento micobacteriano. A enzima Inosina Monofosfato Desidrogenase (IMPDH, EC 1.1.1.205) ? uma enzima chave na bioss?ntese de nucleot?deos de purina, pois participa de uma etapa limitante na s?ntese de novo de nucleot?deos de guanina, a partir de inosina 5 -monofosfato (IMP). Ela catalisa a oxida??o de IMP a xantosina 5 -monofosfato (XMP), com concomitante convers?o de nicotinamida adenina dinucleot?deo (NAD+) ? sua forma reduzida, NADH. Essa rea??o controla os n?veis de nucleot?deos de guanina e inibidores da IMPDH t?m sido utilizados como agentes imunossupressores, antic?ncer e antivirais. Recentemente, a IMPDH de M. tuberculosis (MtIMPDH) foi descrita como um alvo antimicobacteriano promissor e inibidores desta enzima t?m sido reportados. Neste trabalho, foi realizada a clonagem da regi?o codificante do gene guaB2, a express?o e a purifica??o da prote?na MtIMPDH. A MtIMPDH recombinante apresentou uma massa molecular m?dia de 54.775 Da e a an?lise atrav?s de Espectroscopia de Absor??o At?mica em Chama (FAAS) e Espectroscopia de Emiss?o ?ptica com Plasma Indutivamente Acoplado (ICPOES) identificou um ?on K+ por subunidade. Os experimentos de rea??o cruzada, utilizando glutaralde?do, mostraram que a MtIMPDH pode existir como um tetr?mero em solu??o. Os estudos de cin?tica em estado estacion?rio revelaram que a atividade catal?tica da MtIMPDH ? dependente de c?tions monovalentes, principalmente K+. Os estudos de velocidade inicial e inibi??o pelos produtos sugeriram que a cat?lise procede atrav?s de um mecanismo cin?tico sequencial Bi Bi ordenado, no qual o IMP associa-se primeiramente ? MtIMPDH, seguido pela liga??o do NAD+, e que a transfer?ncia do hidreto n?o ? a etapa limitante da rea??o catalisada pela enzima em estudo. Al?m disso, a inibi??o pelo substrato NAD+ indica que a libera??o dos produtos ? ordenada, onde o NADH ? o primeiro produto a ser liberado. Os estudos de perfil de pH indicaram que a desprotona??o de um grupamento com valor de pK em torno de 8,2 ? essencial para a atividade catal?tica da MtIMPDH e, que amino?cidos cujas cadeias laterais possuem valores de pK pr?ximos de 7,5 e 9,0 est?o envolvidos na liga??o ao NAD+. Os dados aqui apresentados s?o discutidos com base em estudos cin?ticos e estruturais dispon?veis de IMPDHs de diferentes organismos e podem auxiliar no desenvolvimento de compostos inibidores para a enzima em estudo. Al?m disso, a identifica??o de genes essenciais para o crescimento bacteriano representa uma etapa importante no desenvolvimento de drogas. Assim, foi realizada a mutag?nese s?tio-dirigida por substitui??o g?nica, a fim de avaliar a import?ncia do gene guaB2 no crescimento do M. tuberculosis H37Rv. Nossos resultados sugerem que este gene ? essencial para o crescimento in vitro do M. tuberculosis H37Rv e a confirma??o da essencialidade permitir? a valida??o do produto deste gene como um alvo para inibidores. Os dados obtidos a partir da caracteriza??o cin?tica da enzima e da substitui??o g?nica representaram o ponto de partida para o planejamento, sele??o e testes de poss?veis inibidores da MtIMPDH. Entre os compostos qu?micos sintetizados, um deles apresentou valores de Ki na faixa de nanomolar e apresentou perfis de inibi??o n?o-competitivo e incompetitivo em rela??o aos substratos NAD+ e IMP, respectivamente. A caracteriza??o da MtIMPDH e os resultados preliminares de inibi??o desta enzima representam passos cruciais no desenvolvimento de novas drogas para o tratamento da TB. Assim, estes dados podem ser ?teis para um melhor entendimento sobre o metabolismo do M. tuberculosis e podem servir como base para o desenvolvimento de estrat?gias terap?uticas objetivando o controle da TB
O jornalismo nas narrativas das cr?nicas de Rachel de Queiroz e Maria Judite de Carvalho
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Previous issue date: 2018-03-22Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPESThe present thesis aims to understand, if and how, Rachel de Queiroz and Maria Judite de Carvalho in their narratives of the published chronicles, respectively, in the magazine O Cruzeiro and in the Di?rio de Lisboa, used values and characteristics that composse the journalistic ethos modern, created to the information field. The analytic inspiration has a theoretical-philosophical basis in hermeneutics and, therefore, intends to interpret the narratives of the columns of both journalists, having as a parameter Hermeneutic Circle of Paul Ricoeur (2010) from this author?s Action and Interpretation?s Theory, which structures of pre-figuration, configuration and refiguration of the narrated actions, gain projection in the way of narrating the world in its time. The intention is to perceive through the interpretation chronicles? narratives published in ??ltima P?gina? e ?Rect?ngulos da Vida?, traces that can evidence journalism model forged in modernity regime of historicity, considering the journalists mentioned were also writers and, therefore, associate to the literary field where the chronicle, this investigation?s object, has different characteristics. The study, after the interpretative process, proves the thesis that the analyzed narratives reveal a great absorption of values associated to the way of being of modern journalism.Esta tesis de doctorado tiene como objetivo entender, si y c?mo, Rachel de Queiroz y Mar?a Judith Carvalho, en las narrativas de cr?nicas publicadas, respectivamente, en la revista O Cruzeiro y el Diario de Lisboa, se apoderaban de los valores y de las caracter?sticas que conforman el esp?ritu period?stico moderno, creado para el campo informativo. La inspiraci?n anal?tica tiene base te?rico-filos?fica en la hermen?utica y, por lo tanto, tiene la intenci?n de interpretar las narrativas de las columnas de las dos periodistas, teniendo como par?metro el C?rculo Hermen?utico de Paul Ricoeur (2010) a partir de la Teor?a de la Acci?n e Interpretaci?n de este autor, en que las estructuras de pre-figuraci?n, configuraci?n y refiguraci?n de las acciones narradas, ganan proyecci?n en el modo de narrar el mundo en su tiempo. La intenci?n es percibir a trav?s de la interpretaci?n de las narrativas de las cr?nicas publicadas en ??ltima p?gina? y ?Rect?ngulos de la vida?, rasgos que puedan evidenciar un modelo de periodismo construido para el r?gimen de historicidad de la modernidad, considerando que las periodistas eran tambi?n escritoras y, por lo tanto, pertenec?an tambi?n al campo literario donde la cr?nica, objeto de esta investigaci?n, posee caracter?sticas distintas. El estudio comprueba la tesis de que las narrativas analizadas revelan una gran absorci?n de valores asociados al modo de ser del periodismo moderno.A presente tese tem como objetivo compreender, se e como, Rachel de Queiroz e Maria Judite de Carvalho, nas narrativas das cr?nicas publicadas, respectivamente, na revista O Cruzeiro e no Di?rio de Lisboa, utilizaram valores e caracter?sticas que comp?em o ethos jornal?stico moderno, criado para o campo informativo. A inspira??o anal?tica tem base te?rico-filos?fica na hermen?utica, portanto, pretende interpretar as narrativas das colunas de ambas as jornalistas tendo como par?metro o c?rculo hermen?utico de Paul Ricoeur (2010), a partir da Teoria da A??o e Interpreta??o deste autor, em que as estruturas de prefigura??o, configura??o e refigura??o das a??es narradas ganham proje??o no modo de narrar o mundo em seu tempo. A inten??o ? perceber, atrav?s da interpreta??o das narrativas das cr?nicas publicadas nas colunas ??ltima P?gina? e ?Rect?ngulos da Vida?, tra?os que possam evidenciar um modelo de jornalismo forjado no regime de historicidade da modernidade, considerando que as jornalistas citadas eram tamb?m escritoras, logo, vinculavam-se igualmente ao campo liter?rio, em que a cr?nica, objeto desta investiga??o, possui caracter?sticas distintas. O estudo ap?s o processo interpretativo comprova a tese de que as narrativas analisadas revelam uma grande absor??o de valores associados ao modo de ser do jornalismo moderno
Pemodelan dan Analisa Reduksi Respon Getaran Translasi dan Rotasi Pada Sistem Utama Oleh Mekanisme Dynamic Vibration Absorber Model Beam dengan Pengaruh Posisi Peletakan Terhadap Pusat Massa Sistem Utama
No full textDalam dunia industri, banyak sekali terjadi getaran pada mesin-mesinnya, baik arah translasi maupun rotasi. Getaran ini bersifat destruktif, sehingga dapat menurunkan kinerja mesin bahkan memperpendek usia pakai dari mesin tersebut. Oleh karena itu, getaran harus direduksi seoptimal mungkin. Salah satu cara yang digunakan untuk mereduksi getaran adalah dengan menggunakan dynamic vibration absorber atau yang biasa disebut DVA. DVA ini merupakan metode yang dilakukan dengan cara menambahkan massa dan pegas pada sistem utama. DVA bekerja dengan melawan arah getaran yang dimiliki oleh sistem utama. Pada penelitian-penelitian sebelumnya, DVA terbukti berhasil mereduksi getaran secara signifikan.
Pada penelitian tugas akhir ini, telah dilakukan pemodelan rancang bangun sebuah simulator getaran dalam skala laboratorium yang mampu merepresentasikan getaran yang terjadi pada kondisi real mesin-mesin industri, yaitu getaran arah translasi dan rotasi. Simulator getaran ini berupa plat persegi datar yang ditumpu oleh empat buah pegas dan diberi gaya base motion oleh motor DC sebagai sumber getar. Getaran yang terjadi pada simulator akan diredam oleh sebuah mekanisme DVA. DVA yang dirancang pada penelitian ini menggunakan model beam dengan dimensi panjang yang bervariasi untuk memvariasikan nilai koefisien pegas, sedangkan lebar dan tinggi memiliki nilai yang tetap. Bentuk DVA ini menyerupai huruf T, dimana beam berfungsi sebagai pegas dengan nilai koefisien kekakuan tertentu yang ditumpu oleh sebuah tiang penyangga dan pada ujung beam diletakkan massa absorber. Variasi-variasi yang dilakukan pada penelitian simulasi ini adalah variasi nilai koefisien kekakuan pegas absorber dengan nilai sebagai berikut : Ka1=1/10 Keq ; Ka2=1/20 Keq; Ka3=1/30Keq , variasi nilai massa absorber berupa perubahan dimensi dari massa DVA sebagai berikut : Ma1=1/10M1 ; Ma2=1/20M1 ; Ma3=1/30M1, dan variasi posisi DVA yang digeser sepanjang satu sumbu dari pusat massa plat datar menuju ujung sisi plat datar sebagai berikut : 0 m, 0,1 m, dan 0,2 m.
Dari penelitian yang telah dilakukan, didapatkan hasil bahwa kombinasi nilai massa absorber yang paling besar, pegas absorber yang paling besar, dan posisi DVA terjauh dapat mereduksi getaran translasi sebesar 99,1% dan getaran arah rotasi sebesar 97,6% ketika sistem bekerja pada frekuensi natural sebesar 36,7 rad/s dan amplitudo 0,03 m. Reduksi optimal getaran arah translasi dan rotasi pada kondisi frekuensi natural dan amplitudo yang sama didapat pada kombinasi nilai massa absorber paling besar, pegas absorber paling besar, dan posisi DVA yang terjauh dari pusat massa sistem utama.
====================================================================
In the industrial world, there is a lot of vibration
occured to its machines, in the direction of translation and
rotation. This vibration is destructive, so it can decrease engine
performance and even shorten the life of the machines. Therefore,
the
vibrations must be reduced as optimally as possible. One of
the solution that used to reduce vibration is using a dynamic
vibration absorber or so
-
called DVA. This DVA is a mechanism
done by adding mass and spring to the main system. DVA works
by vibratin
g against the direction of vibration possessed by the
main system. In previous studies, DVA has been shown to
significantly reduce vibration.
In this final project,
author
ha
s
modeled the design of a
vibration simulator in laboratory scale that represent the
vibrations that occur in the real condition of industrial machine
s,
ie vibration of translational
and rotation
al
direction. This
vibration simulator is a flat square plate
supported by four
springs and given a base motion force by a DC motor as a
vibration source. Vibrations that oc
cur in the simulator will be
reduced by
DVA mechanism. The DVA designed in this study used
beam model of varying dimensions to vary the value of
spring
coefficients, while the width and height have a fixed value. This
DVA shape resembles the letter T, where the beam acts as a spring with a certain stiffness coefficient value supported by a
supporting pole and at the end of the beam is placed by the
absorber mass. The variations
in this simulation
are variation of
the coefficient value of the absorber spring stiffness with the
following value: Ka1 = 1/10 Keq; Ka2 = 1/20 Keq; Ka3 = 1 /
30Keq, the variation of the absorber mass value of the
dimensional
change of the DVA mass as follows: Ma1 = 1 /
10M1; Ma2 = 1 / 20M1; Ma3 = 1 / 30M1, and the DVA position
variation is shifted along one axis from the center
gravity
of the
flat plate mass to the end of the flat plate as follows: 0 m, 0.1 m,
and 0.2 m.
From the research that has been done, the result shows
that the combination of
the
largest
mass absorber value,
absorber
spring
value
, and the furthest DVA position can reduce
translational vibration by 99.1% and rotational
vibration by
97.6% when
the syst
em works on frequency n
atural equal
s to 36,7
rad/
s and amplitude 0,03 m. The optimal reduction of
translational and rotational vibration at the same natural
frequency and amplitude is obtained by combining the l
argest
absorber mass value
, the largest absor
ber spring
value
, and the
furthest
DVA position from the
center gravity of main system
An 15N study of the effects of nitrate, ammonium, and nitrate + ammonium nutrition on nitrogen assimilation in Zea Mays L.
No full textBibliography: leaves 113-134.A brief review of the literature on the effects of nitrate and ammonium nitrogen sources on plant growth, and the assimilation of those nitrogen sources, has been presented. A water culture technique for the growth of maize was developed. The use of a gravel rooting medium with nutrients recycling through the rooting medium, and an iron supplement in the form of ferric citrate, resulted in superior growth of nitrate-fed plants in comparison to that observed with a hydroponic growth technique and a standard Long Ashton nutrient solution. The effects of nitrogen source on plant growth, organic nitrogen and inorganic nitrogen contents, and the rates of incorporation into nitrogenous compounds were studied. The observed differences were explained with reference to the effects of the various nitrogen sources on the physiology of the plants. The experimental techniques included assays of the enzymes nitrate reductase and glutamine synthetase, whole plant growth studies, and the analysis of nitrogenous compounds of xylem exudate and those extracted from the leaf blade, leaf base, and root regions of maize plants after feeding with a nutrient solution containing nitrogen as 15N
0001
No full textTHE DAIUr PaVLO ALTO TIMES.
************* *********
Be Healthy ;
The surest and safest way to ]
nreservo Or regain your health **;
j to be careful what you eat. 9
ivhen you buy groceries be y
.-_ lure and gel the best quality, t
J reasonable prices and prompt 9
lead in the gro- -*-
vice
La Piere & Son i
521 Ramona St. 5
.-•^.'•■•*>.(#-j»**fiJn,*s
Hnv>- any ditltrully lit s*-li-rting no
appro'irf'Ue -Yum-. *,i*c-i-|it'.'
Call and un our line or olckrl
pbited wan-, especially our elejjniil
lMtlin-.nu trhmnint——t«'«i-l •»»?**-
gins*, hotders, soup tup*., luilh seats,
etc., etc.
CALL AND 8KB Oil! OIL
BEATERS.
Christensen-
Darling Co*
2*1 I'NIVKIISITV AVKNIK.
tum*'ni***ini***nk***'ni***'**
Gents!
f
Your Laundry
4 Will come back on time look- y
1 Ing neat, with no saw edges *.'
£ U sent to tbe Stanford Laun- **
j dry-
0 The latest improved ma*
J colnery and skilled workmen a*?
suable us to guarantee you '
£ satisfaction.
£ Telephone Red til.
I Stanford Laundry
( Cor. Ramona Street
t and Forest Ave.
LPALO ALTO
f^nf*nf4nf4nf4nf4nf4nf4n.<^^
Stanford
Home Bakery
JOHN NICOL, Proprietor
AU kinds of Bakery Goods.
Cakes and Pastries for entertainments, parties and weddings a specialty. Only the
best materials used.
315 University Are. Palo Alto
NEW PLAN FOR
PEARY HAS DECIDED TO MARK
ONE MORE Kl-'FORT TO
III. \i ll NORTH POLK.
i Will *-ii-.i-i ii- Hut Not Acconi'
pany Sledge* 1'arfi-**. From V**u
M V ■ ii.'...l.|U,iii. i •■
Now York, Dec. =0.—Friends of
Commodore Robert K. Peary, the
Arctic explorer, stated today tbat th*
bolder of the -'farthest north" record
of 8" deg. ti mln. has practically decided to niaku auoipcr (rial In search
of the north pole, but one unlike any
of bis former trials, ll Is stated thai
In bis new attempt Commaudei
Peary will go as the head of tbe expedition, but be will uot be thu lender of the Ice dash Journey. He will
direct the expedition from the shir
or the winter quarters of the expedition.
Tbe Roosevelt, wblch is to be th
ship the second time, wlll make bet
winter quarter* In the vicinity of thi
north end of (.rant Land. Peary will
remain by the vessel, sending sledgt
parties to cover the Intervening 4S-U
miles that rest be.w-.-oa Sberldan. tin
base of the operations, and the north
pole.
Another lunovation which Feary i*
giving considerable thought to but
which does not meet with bla ontlr<-
approval, is a suggestion made by
some of bis friends that he pick a
crew for tht- Roosevelt from volunteers ln the United States navy.
Shaw May lie Head of Mniual Lift
New York, Dec. 20.—There is i
growing belief ln financial circle
that Leslie M. Shaw, when be retire
from the Secn-turyship of. tbe Treaa
ury Department on February 1st wil
became tbe head or tbe great Mutuul
Life Insurance Company of this cult Is said tbat the position has not m
■ t been formally tendered him, bu1
ha1 in- has been sounded on the sub
< - ar il ta not averse to the Idea.
The position would carry with it :
•alary or 176,000 to i0G,0*JO a year
.ad would place Mr. Shaw In a seal
ii great power and dignity In tlu
,...i,.(i:.| world.
, . ..iiiiilutu of Mr. Shaw said ye*
■i.-tary Shaw can he president o
1; - mutual Uf* If he chooses. H
b -ii told this much by the eon
. >1ttni Interests In the company
■"'.(• Secretary has not given then
"*y dellnlte answer in the absor.-'
•'. a fiirmul leader by the board n
rcBtees, hut It la perfectly safe .
-v ■;,;:[ when such an offer Is mad
Mr. Shaw Will accept."
Puna Tfiief to Give Christmaa GUI
x... fork, Dec. to. —A Christina
•hopping tragedy developed lu t<
Police Court here yesterday wh
Mrs, Smith was arraigned for sit,
log toys in a department store. Tb.
woman told a tearful story, whlc!
moved the Judge and spectator*.
She said her husband had given hei
Jin to buy toys for their four child
ren, all he could afford. When ah<
reached the shopping district she wa:
dlamayed to find that he pocket hnd
been picked and the money stolen.
Rather than disappoint thu children
of the t'hi-1-.t inns joys, she decided to
turn thief. Her story was Investigated, lound to be true and Mm,
Smith was discharged, the department oftlclabi voluntarily withdrawing the charge after the judge and a
number of persons in court hnd offered to par for tbe stolen goods.
MILLIONAIRF FATALLY HURT-. j
!;. T. Gamble Falls Into Hole Is j
Street Mini.- by Storm.
San Jose, Dec. 20.—E. T. Gamble, j
a retired soap manufacturer, whose;
home Is at Palo Alto, was probablyj
fatally injured by a fall at Pacific'
Qrove late last evening. Gamble waa
found unconscious at tbe bottom of a
bole made tn the street by the recent
heavy storm. He was badly bruised
about thu bead and has since re*
malned ln a stupor. Hls.wlfeand two
sups were summoned from Palo
ARo late last nlgbt. Giamblo was
attending a meeting of the stockholders or the Great Western OO
Comiany at Pacific Grove.
The injured man is of the Arm ofJ
Proctor A Gamble of Cincinnati, but Washington, Dee. 20—Beer halts
retired from active business several;*"1 •*v«ral branches of tbe National
years ago and made his home at Palo! llomo lor ■««■»"» Volunteer Sol-
Alto. HI. fortune Is estimated ln the! Govvru
ton. of f-*nt<--- ment aggregating 56»,«164 d-trlng
the last year, according to tbo anntml
j report of Colonel John L. Chamberlain, Inspector General, whose aunu-
I al ruport to the Secretary of War is
' one of tbe strongest rucommvr.dn*
tlons made for the retention ot tbe
j PS***********K******i*m0H***********************»J
CANTEENS DO A THRIVING BU8I-
M -- \ I HOMES FOR DIS.UILKD
Vill.l Ml.l.li SOLDIERS.
Famine Threatens 15,000,000 People
In I hi ii.i— Scheme to Ln tr *l i .iiii,-
Amcricaus Into tbe U.S. Navy.
NO DANGER OF WAR
JAMXESK AKK TOO SENSIBLE! ^^ ,„„„„ „, „,„, bQmsa
AX1. UEV8L.HBAJDED TO GO TO ! wr
WAR OS SCHOOL ISSUE.
Ui
New York,
Alexander Th
Dee. 20.—Profess,
formerly
"Tne beer hail 1 believe to be a
moHl valuable ui;ent la 'urtberlnE. th.
coinfort, contenini.tu, health nnd
aeneral srcllare of .he meniln;..
Nearly all members aro of adnnea.1
cbalr of Knallsh law In tha Imperlnl; ago. their habits are formed and II
University al Toklo. Japan. In an ad- beyond possibility ol Chans.. Tbv.r
dress on "Japane... l.aw snd Pro- '< pensions furnish Iho means wh.'i »•
cednre." al a dinner of Ihe Phi Del;, i wllh to get drink, and Ihoso who d»-
Phi fraternity al the Aldene Club «•"- drink can and will get IL ln tb.
Monday, wa. Interrupt.* wllh the beer ball Ihcy obtain beer ol the
Question as lowlieiber he iboilBln Hie' purest and best quality, and the
school Issue lu California would cau.e amount consumed can be and I.
war between the l'nlted Slaies and, strictly re-ulated. Should thc beer
Japan. Professor Tlson replied: | hall be abolished the money no»
"The Japanese are too seslble and' spent at the beer hal's—In fact. ..
level-headed to ao to war on such il much larger »um—would ba spent In
quesllon. The Government will turn| tho neighboring saloon, aud dlTM,
their populstlon into Korea and Jlan-1 *nd Instead of puro bear they woul :
churla to develop lhal country rather, gel cheap bear and had liquors. Ih.
than bo a source of Irritation lo Iboj prollls which now ate esponded f<»
L'nlted Slates. The Japanese hnve the pleasure, comfort and general
useful leader, and counsellor., anj welfare of members wonld be lost lc
they have every confidence In them j them, nnd would so Into tbo pockets
and tbe manner fn which Ihcy have; of saloonkeepers."
handled questions In thc paat bas
been satisfactory lo all concerned., I'*!"*"" Waters Destroy Crops.
The suggestion of wnr Is absurd.' Washington. Dec. 20.—Official ad-
There are In Japan, as In this country! Ices received hero from thc Perfect
•yellow journals,' and they try to I *>' Hualnnfu. regarding tbe famine In
picture thing. In a horrible light, hut | North Klnngsu, China, confirm the
the population as a whole pay no at-' .torlea of suffering and want among
tention to the articles. ! 'hc people or that section. The crop.
__^_____^___ . arc roporled as being almost a tot
Ki44H44i4t4H44iU.4iit4iU4HZ4i4.4iii.£
% Blacksmithing f
% —«»—
Horseshoeing ]
£ Bring your work to the old- £
4 establixb-"- firm. Oar workmen Z
£ are asperieneed, our oquipmoiit £
j complete, and onr work Is first* 5
J class. -
| Vandervoort & Co. j
Swllelimaii Killed by Trnln.
Santa Cruz. Cal., Dec. 20.—John
Lenx was killed last night by beta-trim over by the 7:15 passenger train.
The body was found at the side of
the track about, 100 yards from Husk alio g rink at tbe beach with hin
head badly crushed. No one saw tbe
accident. The body was Identified
by Southern Pacific Agent Michael*
son. who recognized him as a railroad switchman. Lens has lived
alone ln a cabin near the beach. He
waa Ifi years of Age nnd a native of
Switzerland.
6*
mn m nfanf* r\.mnf*nf*nf*nmnm
STANFORD Al'TOMOBILK
GARAOR.
Sll Alma Street
Automobile and Motor Cycle Repairing, Orandlng. Polishing. Model,
Work, Dross and Iron Castings, Nickel Plating, Electrical Repairing. Ma-
chine Screws and Supplies.
Phone Mala lit
King Oaeai Improving.
Stockholm, Sweden, Dec. SO—King
Oscar continues to ranke steady progress towards recovery.
Tbe latest bulletin says: "The
King pns-tvd a quiet night. His temperature this morulug was 99.1, and
his heart action was stronger. Other*
wise his condition Is unchanged."
Tug Goes to Aitl ln Saving Steamer.
Norfolk, Va.. Dec. 20—The wrecking tog Rescue sailed yesterday with
the wrecking barge Sbarp for Kingston, Jamaica, to make an effort tr
float the Uamburg^Amerlcan tourist
steamer Prlnzessln Victoria Lulse.
.shore off Port Royal.
Pllta HEMAOB8 THEATER.
Orplu-uin. Fur liter ly a RuDOlU "**Iii«*-
Hall. !■ Rarely Saved FtU** FUm.-
Boston, Dec. 20.—Fire yeslenlit*-
causetl heavy damage in the blue*
bounded by Trcmon', Droomfiell.
Washington and Winter Streets, and
although the flames were conliiuil
practically to one structure—th<
Studio building In Themoni itrael
lt for a tlmo threatened to eaust
greater datuug*--.
The fire broke out on the low-r
floor of the Eldrlge & Peabody fornl-
ture establishment and quickly Kwepl
op through six floors of the fitm'i
section of the Studio building. Tin
rno' r..n .... ■ .,,., nm inmoet] acros-i
* norrow alley to the room of th<
Orphuuiii ili.aliK-i. i-jiuit-tl.v ....
ton's famous music hull, and to the
top of ibe building occupied by tbi
Talbot Company, clothiers. In Wash
Ington street. The llames did in
considerable damage to both structures, but the Tabolt building was
flooded by bursting hose.
The firemen bad to fight In a narrow alley on Ice-coaled ladders and
fire escape** and with tbelr own
bodies encased In Ice.
A rough ***HniB.e of the proper;;,
loss palcos the totnl nt about |1B0,.
000, Of Which Eldrldge & Peabody
bear about ITf.,000 and the Talbot
Corapnny IB0.000. A nhmber of artists, architects, dentists and oth.-r*
In the Studio building were burned
out.
THE BANKOFPALO ALTO
Authorized capital 100,000
Paid up 40,000
Surplus and undivided profits... 30,000
GEO. R. PARKINSON, President.
JOSRPH HUTCHINSON. Vlee-Pn*-*-,
C. 8. DOWNING, Cashier.
H. F. CONGDON, Asat Caahler.
Statement of Tbe Rank of Palo Alto, Dec. 0. 1BOO (Condensed)
Resources.
Loans and discounts 2.00 to 40,000.00
Surplus and uudlrldsd profit. 85,320.07
Du- d.poritora 595,353.9-
1074.674.89
^.-a!'.«'-*»yts«'.i«'«»'«*.^'it.yfc^'i^^
i
I
Are You Uncomfortable?
Maybe It's because you aro trying to economise by using
cheap or adulterated coffee. You will forget all your trot-Men
whon you drink thc famous Delmonte Blend of Mocbn and
Java. For sale only at
COMPTON'S TEA-COFFEE STORE
*riai--82S University Avenne Phone Main 88.
GAS! GAS! GAS!
ft R-aTjes ft
lias"* lias
VI V-faw/ (iraies and Logs Vivf-O
Ofeas
Lanndrr Stoves
Soldering Inroiccs
failure In Tao Yuen, and It Is statud
that by the New Year tbe meag-
supply of provisions will be exhausted.
The conditions In An Tong ■■■■■•
Funlng townships uro still worse, tin-
crops being practically a total failure. The country over)*where U
under water, and for a distance pi
fifty miles the people were compelle--
to wade tbrough water from kfttae-
deep to wnist-deop, and In some
places up to their necss.
The Period state* that In tb*
stretch of country Immediately w<
1 of Tslng Uo what formerly was a
fertile plain covered with good crops
and prosperous hamlets is now a rafl
lake, extending twenty miles at lit-
' narrowest point and Btretchlng for
■over forty miles toward the uotnli-
west.
"Here and there," the Perfe-,-;
says, "are groups of cottages whkb
j arise ubove the sheet of water am'.
1 can only be reached by boats. Th'
1 people are in a state of absolute des-
: Ututlon, nut only their crops, but
also tbe reeds which constitute their
fuel, being destroyed hy the Hoods."
An urgent appeal is made to tin-
people of all foreign lands to aid tin*
stricken people, whom State Department advices nlready have placed vt
15,000,000 souls.
A Gilded Itcirnilllng Ship.
Washington. Dee. 20.—Uncle Sam
has devised a new scheme (or retrieving the waning interest of youths in
the United Slates navy. Tbe 111
! posters displayed at postoffTces
Roni KM Pay tbe Debts. throughout the country representing
).—Madame Gould,j -jnU<,,i Stat(-B sailors In resplendent
costumes having failed to attract the
desired number ot recruits, the Navy
Department ban decided to equip a
the former Countess de Cnsu-llm*.
has been victorious ln the suit
brought by creditors and money
lenders against ber with the object! trttVC*inB recrulling ship as an object
of making her Jointly respons'.iil**
with the Count* for the tatter's debts
Thirteen of tlte IHieen cases were dismissed today by the court with co*ui
against the plaintiffs.
Manitoba Will O-tvn Its T.-l.-ph.■■■■-..
lesson to the American youths.
Thin glided ship, tbe converted
yacht Wasp, will be sent to visit th1
various South Atlantic and Qui
ports. At each port young men will
be invited to inspect the recruiting
ship Id the belief that they will be-
Gas
Besl-u-r-Jil B«D-es
Candr l-iinuccs
Broilers
No Flues Necessary When You Use Gas
JTHE BEST FUEL IS
GAS! GAS I GAS!
547 HIOH ST.
PHONE MAIN 62
In almost every honse there Is
a room tbat tbe heat from the
other Stoves or furnace fails to
reach. It may be a
weather" aide, or one having no heat
ter In what pert ol the house—whi
hallway—it can soon be made snag aod cozy with a
PERFECTION
Oil Heat«*
"Winnipeg, Man., Doc. 20.—Ry un come envious of tho lDt of the Ball-
overwhelming majority Manitoba yes-! 0r8 on board and with a new fount!
terday voted In favor of government! longing for the sea-taring life will j
ownership of tong telephone lines; enlist.
and miinlcii-al owuersaip of local j
exchange. Hon. R. P. Robing Pr"-' Bishop McCnbe Dies From Apoplexy.
mler of Manitoba, stated he hss al- New York, Dec. 20.-—Bishop Cbas.
ready Instructed the public workH \ C. McCabe of the Methodist Episcopal
department to order supplies for tbi-
eorstructlon of one thousand miles of
telephone lines, whlcn will be commenced as soon as possible.
Kdltor of "Miffing"" Dead.
New York, Dee. 30,—John Armory Knox, at one time widely known
as the editor and proprietor of Texas
Sittings, died suddenly yesterday of
heart disease at his bome.
Church, died in the New York Hospital yesterday morning at E>:20.
Death was due to apoplexy, with
wblch the bishop was stricken several
days ago while passing through thta
city to his home ln Philadelphia.
Mrs. McCabe and tbe bishop's niece,
who hare been with him almost constantly sIbcc he was stricken, were at
the bedside when the noted clergy-
nan passed away..
Does What
Olher Stoves
FailtoDo
(Equipped with Sraokcle- Ice)
Unlike ordinary oil heaters the Pcrtt* gives sstl faction
always. First and foremost it is abaolutcly safe—you cannot
turn the wick too high or too low. Gives intense best aithont
smoke or smell becaase equipped with smokeless device.
Can be easily carried from room to room. As easr
to operate as a lamp. Ornamental as well as useful.
Made in two finishes—nickel and japan. Brass oil fount
beautifully embosse-tL Holds 4 quarts of oil and barns 9
boars. There's real satisfaction iu a Perfection Oil Heater.
J*'*■'■■; v heater warranted. If not at your dealer's writs our i
nearest agency for descriptive circular.
at;ir» the home brtj-*bt.
I- tbe ■alot and t-r-tt lamp
for ali-fouti-l liouwtiold
!■•-•, Clre** a clear, BMady
litht. ritteu "-tit- lale-tt
l-B-*-ro.-*-*1 traiw-. UtAe of henm Xhrootbout aod nickel ->ltttA.
i:»t*-T lamp ».«rTB--;fl. Sullable for library, rim tor room,
■-'■--wiiedraoBi, If not at jr-mr<lealcr'awiltcH*t-e*tre*t agency.
STANDARD OIL CO Ml* ANY
JiajyoLamp
G. H. Allen Oil Co.
HAGKNTS FOR
Perfection Oil Hesters
aad Ra>o Lanpt
(Proprletora *>( ALTO brand hi|;h grade oil. etpecUllyatlapted
lor tber-c beaten- and lampa.
520 High Street I-bone Main 1
Ionic donor/acceptor conjugated copolymers for optoelectronic applications
No full textTese de doutoramento em Química, na especialidade de Química Macromolecular, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraConjugated polymers have attracted much attention, over the past decades, as promising
electroactive materials with various applications, such as batteries, molecular electronic
devices, light emitting diodes (LEDs), organic eld-e ect transistors (OFETs), large area
photodetectors, organic photovoltaic cells and current injection lasers. Linear aromatic
systems that consist of carbon bridged arylene units are of particular interest because
of their unique luminescent properties for organic displays. Among the phenylene type
molecules poly
uorenes (PFs) had emerged as attractive materials for display applications,
due to e cient blue emission, relatively large hole mobility with trap-free transport, high
photoluminescence (PL) quantum e ciencies and ability to change the electronic properties
via modi cation of the polymer structure.
By incorporating molecular moieties with di erent HOMO/LUMO bandgaps, the emission
can be tuned across the visible spectrum, providing excellent prospects for the polymer's
application in various optoelectronic areas. Colour tuning in PFs can be achieved
either by substitution, by controlling the e ective conjugation length, or by blending the
polymer with another emissive material. Through covalent attachment the migration of the
chromophore dye remains inside the polymer matrix and thus, aggregation and poor device
performance are prevented. Moreover, the incorporation of on-chain chromophoric units
may allow for excitation energy transfer and singlet chromophore exciton con nement.
The goal of this work is to develop methods for increasing the electronic energy transfer
within isolated conjugated
uorene based polyelectrolyte chains. Several water soluble
polyf1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]
uorene-2,7-diylg (PBS-PFP)
copolymers with distinct on-chain chromophore dyes were synthesized via Suzuki coupling
and their solution optical properties characterized. In this perspective and based on the
overlap between the emission spectra of PBS-PFP and the absorption spectra of the dyes,
the following red emitters chromophores were employed: porphyrin (DPP), perylenediimide
(PDI) and 4,7-bis(5-thien-2-yl)benzo[c][1,2,5]thiadiazole) (TBTT). On-chain energy
transfer from the
uorene moieties was only observed in the PBS-PFP-DPP and PBS-PFPTBTT
systems, revealing that isolated PBS-PFP-PDI chains in solution do not undergo an intermolecular energy transfer process. Furthermore, singlet-singlet electronic energy
transfer in anionic
uorene conjugated polyelectrolytes (CPEs) with covalently or electrostatically
bound porphyrins was compared and shown to be more e cient for the cofacial
orientation of the chromophores (self-assembled PBS-PFP with an anionic porphyrin
via calcium binding). PBS-PFP with on-chain chromophore dyes copolymers often show
low solubility and aggregate/clusters formation in aqueous media. Therefore, the in
uence
of organic co-solvents and cationic agents, e.g. ionic liquid (Aliquat 336), polyelectrolyte
(poly(allylamine hydrochloride)) and tetraalkylammonium surfactants was studied, in the
dissolution and "break-up" of aggregates.
The resonance energy transfer study (FRET) was extended to the self-assembled systems
PBS-PFP with phenylenevinylene oligoelectrolytes, with the goal of tailoring their
optical and electronic properties. FRET examination reveal that the self-assembled systems
are sensitive to the solvent environment and to the size of the phenylenevinylene
oligoelectrolyte chain.
With the aim of tailoring the optical and electronic properties and solid state morphology
of conjugated materials with a hydroxy-functionalized side chain, a hydroxyalkylsbstituted
poly
uorene was synthesized via the deprotection of a polymer precursor containing
tetrahydropyran (THP) protecting group. Atomic force microscopy (AFM) reveal
substantial morphologic di erences in thin lms spin coated from 1-methyl-2-pyrrolidone
(NMP) and dimethyl sulfoxide (DMSO) solutions. The data re
ect the polymer sensitivity
towards the surrounding media, that directly in
uences it's aggregation behavior. In both
solvents the polymer tends to form nanospheres, however in the lm from NMP solution
the nanospheres are further aggregated into wormlike particles.In den letzten Jahrzehnten haben konjugierte Polymere immer mehr an Bedeutung
beim Einsatz als elektroaktive Materialien wie z.B. in Batterien, molekular-elektronischen
Bauteilen, lichtemittierende Dioden (LEDs), organische Felde ekttransistoren (OFETs),
Gro
achen-Fotodetektoren, organischen Solarzellen oder Lasern gewonnen. Lineare, aromatische
Systeme, die aus uber Kohlensto -Verbr uckten Phenylen-Einheitenvinylenen bestehen,
sind aufgrund ihrer einzigartigen, lumineszenten Eigenschaften f ur organische Displays
von gro em Interesse. Unter den Phenylen-Derivaten haben sich Poly
uorene (PFs)
aufgrund ihrer e zienten Emission blauen Lichtes, der relativ hohen Elektronenlochmobilit
at bei nahezu defektfreiem Transport, der hohen Photolumineszenz-Quantenausbeuten
und der M oglichkeit, die elektronischen Eigenschaften uber die Polymerstruktur zu andern,
als sehr attraktive Materialien f ur den Einsatz in Displays hervorgetan.
Durch Einbau von Bausteinen mit unterschiedlichen HOMO/LUMO-Abst anden kann
die Emission im gesamten Bereich des sichtbaren Lichtes verschoben werden, welches eine
ausgezeichnete Grundlage f ur optoelektronische Anwendungen ist. Die Farbe von Poly
uorenen
kann durch Substituenten, durch Beein
ussung der e ektiven Konjugationsl ange
oder ber Vermischung mit anderen Emittern erreicht werden. Durch einen kovalenten Einbau
des Farbsto s kann hierbei die Entmischung zwischen den Farbsto molek ulen und der
Polymermatrix verhindert werden, um damit verbundenen E ekten wie Aggregation und
meist geringeren E zienzen vorzubeugen. Zus atzlich erm oglicht der direkte Einbau von
Farbsto en in die Polymerkette Energietransfere ekte und das Einfangen von Singulett
Exzitonen.
Das Ziel dieser Arbeit ist es, Methoden zu entwickeln, die zu einer Verbesserung des
elektronischen Energietransfers in konjugierten,
uorenbasierten Polyelektrolyten-Ketten
f uhren. Hierf ur wurden verschiedene Polyf1,4-phenylen-[9,9-bis(4-phenoxybutylsulfonat)]
uoren-2,7-diylg (PBS-PFP)-Copolymere mit unterschiedlichen Farbsto en uber eine Suzuki-
Kondensationsreaktion hergestellt und deren optischen Eigenschaften untersucht. Basierend
auf der Uberlappung des Emissionsspektrums von PBS-PFP und dem Absorptionsspektrums
der Farbsto e, wurden folgende Farbsto e ausgew ahlt und eingebaut: Porphyrin (DPP), Perylendiimid (PDI) und 4,7-Bis(5-thien-2-yl)benzo[c][1,2,5]thiadiazol) (TB
TT).
Der Energietransfer von den Fluorensegmenten auf den Farbsto konnte nur bei den
PBS-PFP-DPP- und PBS-PFP-TBTT-Systemen beobachtet werden, wobei f ur isolierte
PBS-PFP-PDI Polymerketten in L osung derartige Energietransferprozesse nicht gefunden
wurden. Weiterhin wurde der Singulett-Singulett-Energietransfer in anionischen,
uorenbasierten
Polyelektrolyten (conjugated polyelectrolytes CPEs) mit Kovalent oder elektrostatisch
gebendenen Porphyrinringen verglichen, wobei sich eine cofaziale Anordnung als
wesentlich e zienter herausstellt hat. PBS-PFP mit eingebauten Farbsto en-Einheiten
zeigt eine geringe L oslichkeit in Wasser und die Tendenz, in w assrigen L osungen Aggregate
bzw. Cluster zu bilden, sichtbar. Hierbei wurde der Ein
uss von organischen Detergenzien
und kationischen Tensiden, wie z. B. ionische Fl ussigkeiten, Aliquat 336, Poly(allylaminhydrochlorid)
und Tetraalkylammoniumsalzen auf das Aufbrechen und L osen der Aggregate
untersucht. Die Resonanzenergietranfer-Untersuchungen (FRET) wurden schlie lich
auf as selbstorganisierende System PBS-PFP/Phenylenvinylen-Oligoelektrolyt erweitert,
mit dem Ziel, die optischen und elektronischen Eigenschaften gezielt zu ver andern. Zwei
verschiedene w assrige L osungen von PBS-PFP wurden untersucht, die eine mit einem organischen
Kosolvent, die andere mit einem nichtionischen Surfactant, bei zunehmender
Phenylenvinylen-Konzentration. Die Energietransfer-Untersuchungen zeigten, dass die selbstorganisierende
Systeme sehr emp ndlich auf die L osemittelumgebung und auf die Kettenl
ange der Phenylenvinylen-Oligoelektrolyte sind.
Um die optischen und elektronischen Eigenschaften, sowie die Festphasenmorphologie
von konjugierten Materialien uber Hydroxylgruppen in der Seitenkette zu modi zieren,
wurde ein entsprechendes Poly
uoren synthetisiert, welches Tetrahydropyran-Schutzgruppen
als Hydroxylvorl aufer enth alt. Untersuchungen per Rasterkraftmikroskopie (AFM)
zeigten deutlich unterschiedliche Anordnungen in Filmen, die mittels Spin Coating aus 1-
Methyl-2-pyrrolidon-L osungen (NMP) und Dimethylsulfoxid-L osungen (DMSO) erhalten
wurden. Die Resultate zeigen eine hohe Emp ndlichkeit der Polymeranordnung gegen uber
dem L osemittel, die einen direkten Ein
uss auf das Aggregationsverhalten aus uben. In
beiden L osemitteln bildet das Polymer kugelf ormige sph arische Nanopartikel aus, wobei
sich die Kugeln in dem aus der NMP-L osung generierten Film zu wurmartigen Partikeln
zusammenlagern.Os pol meros conjugados t^em atra do, ao longo das d ecadas, consider avel aten c~ao como
promissores materiais electroactivos para v arias aplica c~oes, tais como: diodos emissores de
luz, transistores de campo el ectrico, fotodetectores de elevada area, c elulas fotovoltaicas
e lasers. De entre os pol meros conjugados os sistemas arom aticos lineares que consistem
em liga c~oes de carbono fenileno s~ao de grande interesse em dispositivos org^anicos, devido
as suas propriedades luminescentes. Na classe dos compostos de fenileno os poli
uorenos
emergiram como excelentes materiais, cuja aplica c~ao em dispositivos se encontra intrinsecamente
relaccionada com a sua emiss~ao na zona do azul no espectro de ultravioleta,
com o elevado rendimento qu^antico de
uoresc^encia e com a facilidade de altera c~ao das
propriedades electr onicas atrav es de simples modi ca c~ao estrutural.
Nos pol meros conjugados e poss vel obter emiss~ao de luz que cubra todo o intervalo
do espectro do v sivel, por incorpora c~ao de m onomeros com diferentes energias entre as
bandas HOMO e LUMO. Este processo e conseguido ou por substitu c~ao das unidades
monom ericas, por controlo da conjuga c~ao da cadeia polim erica, ou por dopagem do pol mero
com outro material, tamb em ele emissivo. Atrav es de liga c~ao covalente entre as unidades
de mon omero e crom oforo e poss vel con nar a migra c~ao de transfer^encia de energia para
o crom oforo dentro da matriz polim erica; desta forma, s~ao evitados fen omenos como a
agrega c~ao e a fraca performance dos dispositivos.
O presente trabalho tem como objectivo o desenvolvimento de m etodos que aumentem
a transfer^encia de energia electr onica dentro de cadeias isoladas de polielectr olitos baseados
em unidades de
uoreno. Deste modo diversos copol meros polyf1,4-phenylene-[9,9-bis(4-
phenoxy-butyl-sulfonate)]
uorene-2,7-diylg (PBS-PFP) com diferentes cr omoforos incorporados
na cadeia polim erica principal, foram sintetizados por acoplamento de Suzuki e estudadas
as suas caracter sticas fotof sicas. De acordo com a perspectiva mencionada e tendo
por base a sobreposi c~ao espectral entre o espectro de absor c~ao dos crom oforos e o de emiss~ao
do PBS-PFP foram seleccionados os seguintes
uor oforos emissores de luz vermelha: por -
rina (DPP), perilenodiimida (PDI) e 4,7-bis(5-thien-2-yl)benzo[c][1,2,5]thiadiazole) (TBTT).
A transfer^encia de energia das unidades de
uoreno para as de
uor oforo apenas foi observada nos copol meros PBS-PFP-DPP e PBS-PFP-TBTT; este facto e indicativo da presen ca
em solu c~ao de outros processos intermoleculares de desactiva c~ao dos estados excitados do
copol mero PBS-PFP-PDI. O mecanismo de transfer^encia de energia singuleto-singuleto
foi provado dependente da orienta c~ao dos crom oforos, de acordo com o estudo efectuado
em dois copol meros ani onicos com diferentes orienta c~oes do
uor oforo de por rina; sendo
mais e ciente quando a por rina se encontra numa posi c~ao cofacial relativamente a cadeia
polim erica. A incorpora c~ao dos
uor oforos estimula a natureza hidrof obica do polielectr olito
ani onico PBS-PFP em solu c~ao, que resulta na forma c~ao de agregados e em fraca solubilidade.
Por forma a contornar os efeitos mencionados os copol meros foram dissolvidos em
misturas de agua e co-solventes org^anicos e a sua intera c~ao com surfactantes, polielectr olitos
e l quidos i onicos cati onicos testada.
O mecanismo de transfer^encia de energia de F orster foi observado em sistemas de PBSPFP
auto-agregados com olig omeros cati onicos de fenileno vinileno. De um modo geral,
a emiss~ao do sistema apresenta tanto caracter sticas do copol mero como dos olig omeros;
no entanto e sens vel ao solvente utilizado e ao tamanho da cadeia do olig omero, sendo
ideal em misturas de agua/dioxano (1:1, em termos de volume) e em olig omeros de quatro
unidades monom ericas.
E
ainda apresentada a s ntese de um copol mero n~ao i onico, com grupos hidr oxilo nas
cadeias alqu licas, sintetizado atrav es da reac c~ao de desprotec c~ao dos grupos tetrahidropirano
do pol mero percursor. O pol mero apresenta diferen cas nas propriedades opticas em
solu c~ao, conforme a polaridade do solvente utilizado, que se re
ete na morfologia em lme e
se encontra directamente relaccionado com a forma c~ao de agregados. Microscopia de for ca
at omica realizada em lmes do pol mero revelou a existência de estruturas de nano-esferas,
que dependendo do grau de agrega ção podem apresentar uma morfologia de wormlike.Fundação para a Ciência e Tecnologia (FCT) atribuiu a bolsa de Doutoramento (SFRH/BD/36666/2007
