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Investigation on Laf3/Si Structure as Light-Addressable Potentiometric Fluoride (F‾) Sensor
Get PDFIn this article LaF3 films in LaF3/Si structure have been investigated for the measurement of fluoride ions in aqueous solution with higher accuracy using light-addressable potentiometric sensing technique. LaF3 films were directly grown on Si by vacuum evaporation. The effects of LaF3-thickness and annealing on the fluoride-sensitivity of the LaF3/Si structures have been studied. Accordingly four different LaF3/Si structures with various thickness of LaF3 (5/50/150nm) layer were fabricated. The structures are annealed at 400ºC for 10 minutes. The un-annealed LaF3/Si structures show very poor fluoride sensitivity. As predicted in the theoretical study structures with thinner LaF3 offer better steepness of the photocurrent characteristics that indicates better accuracy in fluoride concentration measurement. Among the annealed structures, the one prepared with 150nm LaF3 layer shows the best fluoride sensitivity of ≈ 54.5mV/pF in the range of pF1-pF4. Experimental results show a good promise for LaF3/Si structure as a light-addressable potentiometric sensor that can be used for the sensing and imaging the distribution of fluoride ion in aqueous medium with higher accuracy. Keywords: Light-addressable potentiometric sensor (LAPS), Fluoride sensor, Capacitive EIS structur
COMBINED UNCOVERED SHEET-AND-TUBE PVT-COLLECTOR SYSTEM WITH BUILT-IN STORAGE WATER HEATER
Get PDFThis work describes the design and investigation of a simple combined uncovered sheet-and-tube photo-voltaic-thermal (PVT) collector system. The PVT-collector system consists of a support, standard PV module (1.22x0.305m, area=0.37m2, fill factor=0.75), sheet-and-tube water collector and storage tank-heater. The collector was fixed under PV module. Inclination angle of the PVT-collector to the horizontal plane was 45 degree. The storage tank-heater played double role i.e. for storage of hot water and for water heating. The PVT-collector system could work in the fixed and tracking modes of operation. During investigations of PVT-collector in natural conditions, solar irradiance, voltage and current of PV module, ambient temperature and water temperature in storage tank were measured. Average thermal and electrical powers of the PVT-collector system at the tracking mode of operation observed were 39W and 21W, with efficiencies of 15% and 8% respectively at the input power of 260W. The maximum temperature of the water obtained was 42oC. The system was observed efficient for low-temperature applications. The PVT-collector system may be used as a prototype for design of PVT-collector system for domestic application, teaching aid and for demonstration purposes
HIGHLY SENSITIVE TIMER-BASED RESISTANCE DEVIATION TO TIME CONVERTER
Get PDFBased on an inexpensive popular precision timing chip 555 timer, a resistance to time converter is proposed in this paper which is indeed capable of converting resistive and capacitive changes into pulse widths of proportional durations. This converter exhibits a compatibility of wider conversion range with a reasonable level of sensitivity required for industrial applications. The circuit is expected to have utility in oil and water supply schemes. Simulated results are shown to be compared with mathematical derivations, both reporting a good level of resemblance and similarities
OPTIMUM NUMBERS OF SINGLE NETWORK FOR COMBINATION IN MULTIPLE NEURAL NETWORKS MODELING APPROACH FOR MODELING NONLINEAR SYSTEM
Get PDFThis paper is focused on finding the optimum number of single networks in multiple neural networks combination to improve neural network model robustness for nonlinear process modeling and control. In order to improve the generalization capability of single neural network based models, combining multiple neural networks is proposed in this paper. By studying the optimum number of network that can be combined in multiple network combination, the researcher can estimate the complexity of the proposed model then obtained the exact number of networks for combination. Simple averaging combination approach is implemented in this paper which is applied to nonlinear process models. It is shown that the optimum number of networks for combination can be obtained hence enhancing the performance of the proposed model
High Discharge Rate Electrodeposited Zinc Electrode for Use in Alkaline Microbattery
Get PDFHigh discharge rate zinc electrode is prepared from electrodeposition process. The electrolytic bath consists of zinc chloride as the metal source and ammonium chloride as the supporting electrolyte. The concentration of the supporting electrolyte is varied from zero until 4 M, while the concentration of zinc chloride is fixed at 2 M. The aim is to produce a porous zinc coating with an enhanced and intimate interfacial area per unit volume. These characteristics shall contribute towards reduced ohmic losses, improved active material utilization, and subsequently producing high rate capacity electrochemical cell. Nitrogen physisorption at 77 K is used to measure the BET surface area and pore volume density of the zinc electrodeposits. The electrodeposited zinc electrodes are then fabricated into alkaline zinc-air microbattery measuring 1 cm2 area x ca. 305 µm thick. The use of inorganic MCM-41 membrane separator enables the fabrication of a compact cell design. The quality of the electrodeposited zinc electrodes is gauged directly from the electrochemical performance of zinc-air cell. Zinc electrodeposits prepared from electrolytic bath of 2 M NH4Cl produces the highest discharge capacity.ABSTRAK: Elektrod zink dengan kadar discas tinggi telah dihasilkan dengan proses saduran elektrokimia. Takungan elektrolit terdiri daripada zink klorida sebagai sumber logam dan ammonium klorida sebagai elektrolit sokongan. Kepekatan elektrolit sokongan diubah daripada sifar hingga 4 M, sementara kepekatan zink klorida ditetapkan pada 2 M. Ini bertujuan untuk mendapatkan saduran zink yang poros dengan luas permukaan per unit isipadu dan sentuhan antaramuka yang dipertingkatkan. Ciri-ciri ini akan menyumbang terhadap pengurangan kehilangan disebabkan kerintangan, pertambahan dalam gunapakai bahan aktif dan akhirnya menghasilkan sel elektrokimia berprestasi tinggi. Physisorpsi nitrogen pada 77 K telah digunakan untuk mengukur luas permukaan BET dan isipadu liang saduran zink. Saduran zink kemudiannya dijadikan elektrod bagi bateri mikro zink-udara beralkali dengan saiz 1 cm2 luas x ca. 305 µm tebal. Penggunaan membran tak organik MCM-41 membolehkan pembuatan sel dengan rekabentuk padat. Kualiti elektrod saduran zink telah dinilai secara lansung daraipada prestasi elektrokimia sel zink-udara. Saduran zink yang disediakan daripada takungan elektrolit 2 M NH4Cl menghasilkan kapasiti discas tertinggi.KEY WORDS (keyword)): Zinc electrodeposition, High discharge rate electrode, MCM-41 separator, Zinc-air cell and Alkaline microbattery
Rectification And Revival Of Muslim World
Get PDFThe present doldrums position and state of decadence, internal differences, external aggression (geographical and ideological), lack of self-confidence and dependence, illiteracy, political instability, economic disaster, lack of knowledge and wisdom, back benchers in science and technology, education, medicine, trade and business, banking system and defensive incapability of Muslim Ummah prompted me to write this article. Although most of the Muslim nations got their independence because of their dedicated struggle and historic events and incidents but the old masters remained active for a remote control over the Muslim Ummah. Their intellectuals and scholars, individually as well as collectively, have propagated and advised their leadership, the tactics and approaches by which Muslim Ummah can again be enslaved. Writings of S.P. Huntington and F. Fukuyama are clear examples. They are actively gearing the international institutions so cleverly that Muslim Ummah does not even realize their ill motives and objectives. They brought their leadership in a confronting position with Muslim Ummah and hence threatening the world peace. This situation prompted us to look at our principal sources of inspiration, which are, the Qur’an, Sunnah of the Prophet (SAW), and examples of the “enlightened Caliphs” and see if we could work out a seminal guidelines for our rectification and revival. We have gathered together some of these impressions; these are all tentative, nothing final about them, but these are here nonetheless. ABSTRAK: Kehadiran situasi kebelungguan dan keruntuhan, perbezaan dalaman, pencerobohan luar (geografi dan ideologi), kurang keyakinan diri dan pergantungan, buta huruf, ketidakstabilan politik, bencana ekonomi, kekurangan ilmu dan hikmah, ketinggalan dalam sains dan teknologi, pendidikan, perubatan, perdagangan dan perniagaan, sistem perbankan dan ketidakupayaan pertahanan umat Islam mendorong saya untuk menulis artikel ini. Walaupun kebanyakan negara-negara Islam mendapat kemerdekaan mereka kerana perjuangan mereka yang berdedikasi dan peristiwa dan kejadian yang bersejarah tetapi sejarah orang lama yang kekal aktif untuk mengawal kedudukan umat Islam. Keintelektuallan mereka, secara individu dan secara berkumpulan, telah dikembangkan melalui nasihat kepimpinan mereka, taktik dan pendekatan yang Muslim Ummah sekali lagi boleh diperhambakan. Karya SP Huntington dan F. Fukuyama adalah contoh yang jelas. Mereka secara aktif menggerakkan institusi antarabangsa sehingga umat Islam tidak menyedari motif tersirat dan objektif mereka. Mereka telah membawa kepimpinan mereka dalam kedudukan yang dihadapi dengan umat Islam dan dengan itu mengancam keamanan dunia. Keadaan ini mendorong kita untuk melihat sumber-sumber inspirasi utama, iaitu al-Quran, Sunnah Nabi (SAW), dan contoh-contoh "Khalifah pencerahan" dan lihat jika kita boleh merumuskan satu garis panduan pembetulan dan pemulihan. Kami telah berkumpul bersama untuk mengawal perasaan, ini semua tentatif, walau bagaimanapun tiada apa-apa jua yang muktamad tentang mereka.KEYWORDS: SWT (subhana wa taala); pbuh (peace and blessings be upon him); ra (radiallahu anha/u
Comparative Amino Acids Studies on Phac Synthases and Proteases as Well as Establishing a New Trend in Experimental Design
Get PDFABSTRACT: A question addressed in this study is: why similar enzymes are classified into different subclasses? As an example, PhaC synthases are classified according to four different classes (I, II, III and IV). To answer this question we proposed that besides the catalytic residues, the overall amino acids (AAs) present are responsible for the differences observed. The AAs’ composition affects the structure/function/substrate specificity (SFS) of these enzymes. The differences between the classes in various PhaC synthases and proteases were analysed to support our argument. Homology and phylogenic tree of some selected PhaC synthases of different strains (representing the four classes) were demonstrated. The properties of a specific class of enzyme could not be changed into those of another by changing the catalytic residues. Moreover, these differences could not be detected from the proteins’ 3D structures, despite clear differences at the AAs level. Another question was also addressed: could we benefit from the various existing protein databases in the field of biotechnology? To answer this, we introduced a model for an Experimental Design based on the information in the protein database (for strains available in our lab) regarding their ability to degrade castor oil. Two enzymes in the phenol degradation pathway, phenol 2-monooxygenase and catechol 1,2-dioxygenase, and a lipase enzyme were analysed. These enzymes were screened and analysed according to the BLAST-protein database and BRENDA. The comprehensive enzyme information system compared six strains against each other, including: Pseudomonas aeruginosa, Bacillus subtilis, Bacillus pumilus, Bacillus thuringiensis, Bacillus licheniformis, and Geobacillus stearothermophilus. Only P. aeruginosa proved to have the three required enzymes and was suitable for the production of lipases from castor oil (crude castor oil is usually contaminated with phenol) as indicated by the databases. In addition, in vivo castor oil degradation and in vitro lipase enzyme activity were analysed. The apparent lipase activity was 1070 Units/ml. Therefore, this new strategy is recommended to better understand the SFS as well as for using protein database in an Experimental Design.ABSTRAK: Kajian ini berkisar mengenai soalan: mengapa enzim yang sama diklassifikasikan kepada subkumpulan yang berbeza? Contohnya sintasis PhaC dikelaskan kepada empat kumpulan berbeza (I, II, III dan IV). Bagi menjawab soalan ini selain hipotesis katalitik residue diperkenalkan, faktor yang bertanggungjawab adalah asid amino (AAs) secara keseluruhannya. Komposisi AAs memberi kesan kepada struktur/fungsi/spesifikasi substrat (SFS) enzim-enzim ini. Perbezaan di antara kumpulan dalam pelbagai sintasis PhaC dan proteases telah dianalisis bagi menyokong hujah ini. Homologi dan asas phylogenic bagi sintasis PhaC tertentu yang berbeza strains (mewakili empat kumpulan) telah ditunjukkan. Sifat-sifat tidak boleh ditukarkan dengan menukarkan katalitik residue dari satu kepada yang lain. Tambahan pula, kelainannya tidak boleh dikesan dari struktur 3D protein, walaupun perbezaan yang nyata pada peringkat AAs. Soalan lain yang berkisar adalah: Adakah kita mendapat faedah dari pelbagai pengkalan data dalam bidang bioteknologi? Bagi menjawab soalan ini, model Rekabentuk Eksperimen telah diperkenalkan yang berasaskan maklumat pengkalan data protein bagi strains di makmal kami yang boleh degradasi minyak castor. Dua enzim dalam degradasi fenol telah dianalisis, fenol 2-monooxigenas dan catechol 1,2-dioxygenas serta enzim lipas. Enzim-enzim ini telah disaringkan dan dianalisis dengan merujuk kepada pengkalan data protein-BLAST dan BRENDA. Sistem maklumat enzim secara komprehensif terhadap enam strains termasuk Pseudomonas aeruginosa, Bacillus subtilis, Bacillus pumilus, Bacillus thuringiensis, Bacillus licheniformis dan Geobacillus stearothermophilus. Hanya P. Aeruginosa terbukti mempunyai tiga enzim dan sesuai bagi penghasilan lipase dari minyak kastor (minyak kastor mentah selalunya tercemar dengan fenol) seperti yang ditunjukkan dari pengkalan data. Degradasi minyak kastor in vivo dan aktiviti enzim lipase in vitro telah dilaksanakan. Aktiviti lipase jelas adalah 1070 Units/ml. Kami mencadangkan menggunakan strategi ini bagi memahami SFS serta pengkalan data protein dalam Rekabentuk Eksperimen.KEYWORDS: amino acids; model; PhaC synthase; protease; lipase; experimental desig
Solitary Wave-Series Solutions to Non-Linear Schrodinger Equations
Get PDFABSTRACT: In this paper, higher-order dispersive non-linear Schrodinger equations are studied. Their solitary wave-series solutions with continuity of the derivatives and specific discontinuity of the derivatives at the crest are presented. Furthermore, convergence of the series’ solutions is also validated and discussed with the help of graphs. ABSTRAK: Kertas ini mengkaji persamaan Schrodinger serakan taklinear turutan tinggi. Penyelesaian siri-gelombang tunggalnya dengan kamiran berterusan dan kamiran tak berterusan pada maksimum telah dibentangkan. Penumpuan penyelesaian siri juga telah diperiksa dan dibincangkan dengan bantuan graf-graf.KEYWORDS: Schrodinger equation; solitary wave-series solution; continuity and discontinuity of derivatives at cres
Review on Development of Ceramic Membrane From Sol-Gel Route: Parameters Affecting Characteristics of the Membrane
Get PDFThe importance of laboratory scale ceramic membrane preparation using sol-gel technique with pore sizes in the range of 1-10nm is reviewed. Parameters affecting the characteristics of membrane during membrane development are highlighted and discussed in detail. Experimental results from literatures have shown that the correct amount of acid, water, PVA, appropriate membrane thickness, proper control of drying rate, and appropriate temperature profile selection during sintering process are necessary in order to acquire sufficient strength and reduce the formation of crack in the membrane. The different temperature setting during sintering process also influences the size of pore formed.Key Words: Sol-Gel, Inorganic Membrane, Ceramic Membrane, Gas Permeation, Sintering, Sol Properties, Membrane Morphologies, Pore Size Distribution
Influence of Chatter of VMC Arising During End Milling Operation and Cutting Conditions on Quality of Machined Surface
Get PDFMachine tool chatter is a dynamic instability of the cutting process. Chatter results in poor part surface finish, damaged cutting tool, and an irritating and unacceptable noise. Exten¬sive research has been undertaken to study the mechanisms of chatter formation. Efforts have been also made to prevent the occurrence of chatter vibration. Even though some progress have been made, fundamental studies on the mechanics of metal cutting are necessary to achieve chatter free operation of CNC machine tools to maintain their smooth operating cycle. The same is also true for Vertical Machining Centres (VMC), which operate at high cutting speeds and are capable of offering high metal removal rates. The present work deals with the effect of work materials, cutting conditions and diameter of end mill cutters on the frequency-amplitude characteristics of chatter and on machined surface roughness. Vibration data were recorded using an experimental rig consisting of KISTLER 3-component dynamometer model 9257B, amplifier, scope meters and a PC. Three different types of vibrations were observed. The first type was a low frequency vibration, associated with the interrupted nature of end mill operation. The second type of vibration was associated with the instability of the chip formation process and the third type was due to chatter. The frequency of the last type remained practically unchanged over a wide range of cutting speed. It was further observed that chip-tool contact processes had considerable effect on the roughness of the machined surface.Key Words: Chatter, Cutting Conditions, Stable Cutting, Surface Roughness