63 research outputs found
Dimensions of polystyrene particles deposited on mica from dilute cyclohexane solution at different temperatures
Get PDFUsing atomic force microscopy, the height, diameter, and volume of polystyrene particles deposited on mica from dilute cyclohexane solution at different temperatures are determined. Dimensions exhibit a strong temperature dependence. The heights of the deposited particles are only a few atomic diameters, the major dimension being parallel to the mica surface. The number of single polystyrene molecules in a deposited particle cannot be determined directly by atomic force microscopy. However, the maximum number of molecules that may be present in a particle may be estimated, Below 35 degreesC, the particles possibly consist of single collapsed molecules. This number increases with temperature and becomes as large as about 30 molecules per particle at 80 degreesC. The volume occupied by a single chain in solvent is calculated as a function of temperature and compared with observed volumes of dry particles on mica. A linear relationship is observed between single chain volumes in solvent and corresponding particle volumes on mica. On the average, the volume of a single chain in solution is 10 times the volume of a dry particle at the corresponding temperature. Fluctuations of chain volumes that are dominant in solution are also present in the volumes of particles deposited and dried on mica
Rhodamine-immobilised electrospun chitosan nanofibrous material as a fluorescence turn-on Hg2+ sensor
Get PDFA turn-on fluorescence sensing system for mercuric (Hg2+) ions relying on a modified rhodamine B–chitosan fluorophore moiety was developed. This novel sensing approach relies on the simultaneous electrospinning of chitosan and rhodamine B hydrazide with phenylisothiocyanate functionality in hexafluoroisopropanol solution at 3.4 kV cm−1. The electrospun mats exhibited not only considerably enhanced fluorescence intensity in the presence of mercury ions, a result attributed to the ring opening of the spirolactam unit of the rhodamine-based fluorophore, but also a remarkably high sensitivity and selectivity toward Hg2+. In effect, the strategy has the potential to open new avenues in the design and development of other high-performance nanofibrous sensing materials for detecting target metal species of environmental interest
Aggregation of fillers blended into random elastomeric networks: theory and comparison with experiments
Get PDFA theoretical model describing aggregation of filler particles in amorphous elastomers is proposed. The model is based on a counting technique originally used in genome analysis to characterize the size and distribution of overlapping segments randomly placed on a DNA molecule. In the present model, the particles are first assumed to aggregate randomly upon mixing into the elastomer and their sizes are calculated. The sizes and distributions of aggregates are also studied in the presence of attractive interparticle forces. Results of the proposed model are compared with experimental data on silica-filled end-linked poly(dimethylsiloxane) networks. Comparison of the theory and experiment shows that the random aggregation assumption where no attractive forces exist between the particles is not valid and a significant attraction between the silica particles is needed in the theory to justify the experimental data obtained using atomic force microscopy. For filler content below 1.45 vol.-%, the model agrees, qualitatively, with experiment and shows the increase in cluster size with increasing amount of filler. It also explains the increase in the dispersion of aggregate sizes with increasing amount of filler
Effect of filler amount on thermoelastic properties of poly (dimethylsiloxane) networks
No full textEnd-linked poly(dimethylsiloxane) (PDMS) networks were prepared in the presence of fumed silica particles with hydroxyl groups at their surfaces. The silica particles were introduced into the polymer solution prior to end-linking. Hydroxyl ended PDMS chains were end-linked via the tetra functional crosslinker, tetraethoxysilane. The filler content varied in the range 0–5 wt%. Atomic Force Microscopy was used to image and characterize the silica particles. Swelling, stress–strain and thermoelasticity experiments were performed. The temperature coefficient and the energetic part of the force in uniaxial extension are found to increase with increasing silica amount. This observation is ascribed to effects contributed possibly by the adsorption layer around the silica particles
Yaratıcı Endüstriler
No full textKüresel ekonominin odağı mamul madde üretiminden hizmet sektörüne kaydıkça bilgi yoğun sektörlere verilen önem artar. Bu makalede bahse konu gelişmelere koşut olarak demokratikleşme ve refahı artırmak için bireysel yaratıcılığı odağa alan Yaratıcı Endüstriler kavramı irdelenmektedir. Bireysel yaratıcılığın refah yaratacağı varsayımı üzerinden işletme yazınında ve ekonomi dünyasında yaygın kullanılan inovasyon kavramı ile kesişen Yaratıcı Endüstriler, Türkiye’de yükseköğretimi dönüştüren pratiklere doğrudan etki etme potansiyeli taşır. Bunun yanında üzerine inşa edildiği ‘yaratıcılık’ kavramının ardındaki kültürel sorunlar ve bireylerin beklentilerini şekillendiren yeni bir tür öznelliği teklif etmesi nedeniyle Yaratıcı Endüstriler çok daha geniş ve disiplinlerarası çalışmaların konusu olmaya adaydır. Bu çalışmanın amacı Türkiye’de istatistikler, ekonomik pratikler ve teşvikler üzerinden yaygınlaşmaya başlayan kavram üzerine farklı bakış açılarını ve eleştirileri yazına kazandırmaktı
Creative Labour in Turkey
Get PDFIn recent years, the political and academic discourse focusing on the economic potential of creative cultural industries is raising. The idea of creative culture industries which focuses on creativity and symbol production instead of material production presented as a source of prosperity for developing countries. It is claimed that individuals are set free from the routine working life by creative work, which offer flexible and independent work opportunities. At first glance, this change, which is considered to liberate the industrial revolution from the control measures, contains insecurities that burden the responsibility of learning and employment to the individual. The creative labor debate at the center of the creative economy involves the development of an individual's talent set on the one hand and the critique of these risks on the other. This study examines whether the sector dynamics in Turkey developed creative labour by means of online survey method and qualitative analysis. At the same time, aims to reveal the extent of the characteristics in the international literature. The similarities and differences with international literature have been discussed on subjective experiences related to precarious working conditions in Turkey
Palladium nanoparticles by electrospinning from poly(acrylonitrile-co-acrylic acid)-PdCl2 solutions. Relations between preparation conditions, particle size, and catalytic activity
Get PDFCatalytic palladium (Pd) nanoparticles on electrospun copolymers of acrylonitrile and acrylic acid (PAN-AA) mats were produced via reduction of PdCl2 with hydrazine. Fiber mats were electrospun from homogeneous solutions of PAN-AA and PdCl2 in dimethylformamide (DMF). Pd cations were reduced to Pd metals when fiber mats were treated in an aqueous hydrazine solution at room temperature. Pd atoms nucleate and form small crystallites whose sizes were estimated from the peak broadening of X-ray diffraction peaks. Two to four crystallites adhere together and form agglomerates. Agglomerate sizes and fiber diameters were determined by scanning and transmission electron microscopy. Spherical Pd nanoparticles were dispersed homogeneously on the electrospun nanofibers. The effects of copolymer composition and amount of PdCl2 on particle size were investigated. Pd particle size mainly depends on the amount of acrylic acid functional groups and PdCl2 concentration in the spinning solution. Increasing acrylic acid concentration on polymer chains leads to larger Pd nanoparticles. In addition, Pd particle size becomes larger with increasing PdCl2 concentration in the spinning solution. Hence, it is possible to tune the number density and the size of metal nanoparticles. The catalytic activity of the Pd nanoparticles in electrospun mats was determined by selective hydrogenation of dehydrolinalool (3,7-dimethyloct-6- ene-1-yne-3-ol, DHL) in toluene at 90 °C. Electrospun fibers with Pd particles have 4.5 times higher catalytic activity than the current Pd/Al2O3 catalyst
UVC Seed Sterilization BSc Thesis: Software and Control
No full textIn this thesis for the Bachelor’s Degree in Electrical Engineering, a Control Unit (PCB and software) is designed for inside the UVC Seed Disinfection Machine of Team UVO. The machine consists of four modules: the Control Unit, the LED Driver, the motor controller and the power supply. The Control Unit allows a user to input the intensity per wavelength (for possible wavelengths: 255 nm, 275 nm, 285 nm and 395 nm), the exposure time and the motor speed.The design of the machine, including all the modules, is aimed at achieving the optimal wavelength for inactivation and maximum and uniform irradiance, with the ability of changing radiation settings according to the desire of the user.The Control Unit manages communication with the other modules, data storage, the User Interface, safety checks and system enabling. The thesis covers the design choices regarding the entire design, with an in-depth analysis of the hardware implemented safety checks, the graphical user interface and the design of the communication protocol.Due to difficulties regarding uploading the code onto the PCB, not every developed functionality could be tested or implemented. However, the functionalities that were tested, did perform as expected. In addition to this, after the thesis has been submitted, more time will be spent on debugging the PCB, implementing and testing its features.The objective for the graduation project of Team UVO is to provide a proof-of-concept of disinfecting cabbage seeds (Brassica oleracea capitata) from Alternaria using UVC LEDs. This thesis describes design process of the Control Unit module. The results of the decontamination process are provided inAppendix F.EE3L11Electrical Engineerin
Artificial Intelligence and Cultural Production in Public Policies: Discussion of Examples from International Public Policies
No full textThe creative economy is defined as a new economic activity area subject to global competition. However, the relationship between artificial intelligence (AI) and cultural production, as a relatively new technology, has been underrepresented in Western literature and policies. This study discusses the context of AI and Generative Artificial Intelligence (GAI) policies in relation to their cultural and societal implications. Departing from previous studies suggesting that algorithms managed by platforms inadequately encompass cultural authenticity, AI is here considered as a domain containing cultural risks. This study aims to reveal the disadvantages of the Global South by discussing the concerns of exclusion and bias of AI through the public policy texts of developed countries and to contribute to the public policy development process of Turkey in relation to the field of culture. To this end, policy texts on AI and GAI from the eight OECD countries investing the most in AI, the European Union, Japan and Saudi Arabia have been analyzed. Through policy framing analysis, the roles of cultural institutions in policy-making, the framing of bias and cultural diversity themes in the texts, and how policy interventions in the AI field are framed have been examined. In light of the findings that AI is implicitly positioned as a new area of colonialism in developed countries policy documents, a perspective sensitive to cultural policies is proposed for Turkey to produce an inclusive AI policy based on her public administration tradition and technology infrastructure investments
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