Particle formation of hydroxyapatite precursor containing two components in a spray pyrolysis process

The particle formation mechanism of hydroxyapatite precursor containing two components, Ca(OOCCH₃)₂ and (NH₄)₂HPO₄ with a ratio of Ca/P = 1.67, in a spray pyrolysis process has been studied by computational fluid dynamics (CFD) simulation on the transfer of heat and mass from droplets to the surrounding media. The focus included the evaporation of the solvent in the droplets, a second evaporation due to crust formation, the decomposition reaction of each component of the precursor, and a solid-state reaction that included the kinetic parameters of the precursor regarding its two components that formed the hydroxyapatite product. The rate of evaporation and the reacted fraction of the precursor both increased with temperature. The predicted average size of the hydroxyapatite particles agreed well with the experimental results. Therefore, the selected models were also suitable for predicting the average size of particles that contain two components in the precursor solution.     

Intermetallic compounds dynamic formation during annealing of stacked elemental layers and its influences on the crystallization of Cu2ZnSnSe4 films

A combined in-situ investigation using X-ray diffraction and differential scanning calorimetry during annealing was carried out to investigate the formation of intermetallic compounds in the stacked elemental layers and to reveal its influences on the crystallization of kesterite Cu₂ZnSnSe₄. The Mo/Cu/Zn, Mo/Cu/Sn/Zn, Mo/Cu/Zn/Se and Mo/Cu/Sn/Zn/Se stacked films were prepared with a composition resembling a typical kesterite Cu-poor and Zn-rich metallic composition. In-situ experiments during annealing of pure metallic stacked films reveal a dynamic intermetallic compounds formation of Cu₅Zn₈ → CuZn → Cu₂Zn → Cu₃Zn and Cu₆Sn₅ → Cu₄₁Sn₁₁. The CuZn and Cu₅Zn₈ layer formed at the interface of metals/Se may prevent the stacked metallic layers from selenization below 320 °C. On the other side, the dynamic formation of Cu–Zn phases in the stacked films is found to be an origin of a ZnSe gradual formation starting from 320 °C. Phase analysis suggests that the ternary Cu₂SnSe₃ phase forms almost immediately after the formation of Cu₂Se and SnSe. The formation of Cu₂SnSe₃ is indicated by the consumption of SnSe by the Cu₂Se which occurs at 530–540 °C. Crystallization of kesterite takes place above 540 °C. On a phenomenological basis of present results, consequences for the thin film kesterite fabrication for solar cell application are discussed.     

Effect of Ga doping on micro/structural, electrical and optical properties of pulsed laser deposited ZnO thin films

Undoped and Ga doped ZnO thin films (1% GZO, 3% GZO and 5% GZO) were grown on c-Al₂O₃ substrates using the 1, 3 and 5 at. wt.% Ga doped ZnO targets by pulsed laser deposition. X-ray diffraction studies revealed that highly c-axis oriented, single phase, undoped and Ga doped ZnO thin films with wurtzite structure were deposited. Micro-Raman scattering analysis showed that Ga doping introduces defects in the host lattice. The E₂^High mode of ZnO in Ga doped ZnO thin film was observed to shift to higher wavenumber indicating the presence of residual compressive stress. Appearance of the normally Raman inactive B₁ modes (B₁^Low, 2B₁^Low and B₁^High) due to breaking of local translational symmetry, also indicated that defects were introduced into the host lattice due to Ga incorporation. Band gap of the Ga doped ZnO thin films was observed to shift to higher energy with the increase in doping concentration and is explicated by the Burstein-Moss effect. Electrical resistivity measurements of the undoped and GZO thin films in the temperature range 50 to 300 K revealed the metal to semiconductor transition for 3 and 5% GZO thin films.     

Performance Optimization of Parallel‐Like Ternary Organic Solar Cells through Simultaneous Improvement in Charge Generation and Transport

Ternary organic photovoltaic (OPV) devices with multiple light‐absorbing active materials have emerged as an efficient strategy for realizing further improvements in the power conversion efficiency (PCE) without building complex multijunction structures. However, the third component often acts as recombination centers and, hence, the optimization of ternary blend morphology poses a major challenge to improving the PCE of these devices. In this work, the performance of OPVs is enhanced through the morphological modification of nonfullerene acceptor (NFA)‐containing binary active layers. This modification is achieved by incorporating fullerenes into the layers. The uniformly dispersed fullerenes are sufficiently continuous and successfully mediate the ordering of NFA without charge or energy transfer. Owing to the simultaneous improvement in the charge generation and extraction, the PCE (12.1%) of these parallel‐linked ternary devices is considerably higher than those of the corresponding binary devices (9.95% and 7.78%). Moreover, the additional energy loss of the ternary device is minimized, compared with that of the NFA‐based binary device, due to the judicious control of the effective donor:acceptor composition of the ternary blends.     

Finite element modeling and experimental proof of NEMS-based silicon pillar resonators for nanoparticle mass sensing applications

The potential use of nanoelectromechanical systems (NEMS) created in silicon nanopillars (SiNPLs) is investigated in this work as a new generation of aerosol nanoparticle (NP)-detecting device. The sensor structures are created and simulated using a finite element modeling (FEM) tool of COMSOL Multiphysics 4.3b to study the resonant characteristics and the sensitivity of the SiNPL for femtogram NP mass detection in 3-D structures. The SiNPL arrays use a piezoelectric stack for resonance excitation. To achieve an optimal structure and to investigate the etching effect on the fabricated resonators, SiNPLs with different designs of meshes, sidewall profiles, heights, and diameters are simulated and analyzed. To validate the FEM results, fabricated SiNPLs with a high aspect ratio of approximately 60 are used and characterized in resonant frequency measurements where their results agree well with those simulated by FEM. Furthermore, the deflection of a SiNPL can be enhanced by increasing the applied piezoactuator voltage. By depositing different NPs [i.e., gold (Au), silver (Ag), titanium dioxide (TiO₂), silicon dioxide (SiO₂), and carbon black NPs] on the SiNPLs, the decrease of the resonant frequency is clearly shown confirming their potential to be used as airborne NP mass sensor with femtogram resolution level. A coupling concept of the SiNPL arrays with piezoresistive cantilever resonator in terms of the mass loading effect is also studied concerning the possibility of obtaining electrical readout signal from the resonant sensors.     

Collaborative Learning based on Convolutional Features and Correlation Filter for Visual Tracking

International Journal of Control, Automation and Systems - One of the most important and challenging research topics in the area of computer vision is visual object tracking, which is relevant to...     

Physician assessment of patient smoking in Indonesia: a public health priority

Objective

To explore Indonesian physician''s smoking behaviours, their attitudes and clinical practices towards smoking cessation.

Design

Cross‐sectional survey.

Setting

Physicians working in Jogjakarta Province, Indonesia, between October and December 2003.

Subjects

447 of 690 (65%) physicians with clinical responsibilities responded to the survey (236 men, 211 women), of which 15% were medical faculty, 35% residents and 50% community physicians.

Results

22% of male (n = 50) and 1% of female (n = 2) physicians were current smokers. Approximately 72% of physicians did not routinely ask about their patient''s smoking status. A majority of physicians (80%) believed that smoking up to 10 cigarettes a day was not harmful for health. The predictors for asking patients about smoking were being male, a non‐smoker and a medical resident. The odds of advising patients to quit were significantly greater among physicians who perceived themselves as sufficiently trained in smoking cessation.

Conclusions

Lack of training in smoking cessation seems to be a major obstacle to physicians actively engaging in smoking cessation activities. Indonesian physicians need to be educated on the importance of routinely asking their patients about their tobacco use and offering practical advice on how to quit smoking.Tobacco use is one of the greatest causes of preventable deaths and disease in human history. According to the World Bank, four‐fifths of the world''s 1.1 billion smokers live in low‐income or middle‐income countries.¹ East Asian and Pacific countries currently account for about 38% of the world''s smokers and men, especially those aged 30–49 years, account for about 80% of these smokers.² In Indonesia, 59% of male, but only <5% of women, smoke.³ Notably, the rates of tobacco use, especially among adolescents and young adults in East Asia, continue to rise.¹ Although reliable national data are unavailable for Indonesia, estimates in 2004 showed a high incidence rate of tobacco‐attributable mortality and morbidity.⁴ For example, in 2002, the International Agency of Research on Cancer Globocan estimated that the age‐standardised mortality of respiratory tract cancer in Indonesia among men was 68.5 per 100 000 population, but that among women was only 21.5 per 100 000 population.⁵Nations such as Indonesia continue to bear significant health and socioeconomic burdens associated with tobacco use, primarily due to aggressive tobacco industries marketing and the slow progress in tobacco control activities resulting from a strong dependency of the national economy on the tobacco trade.⁶ To reduce the economic and health burden from cigarette smoking, effective measures for smoking cessation and tobacco control are clearly needed. Public health education, and governmental policies such as taxation on sales and restrictions on advertisement may serve as useful tools to limit the use of tobacco products.^7,8 Currently, such measures are lacking in Indonesia.Smoking behaviour and attitudes towards smoking cessation by healthcare providers in Western countries have been studied extensively.^9,10,11 Research findings suggest that asking about smoking and offering advice about cessation help smokers quit.^{12,13,14,15,16} Of equal importance is the observation that the smoking status of healthcare providers may influence their willingness to offer smoking cessation advice to smokers.^16,17 Unfortunately, limited research is available on non‐Western countries in regard to behaviours, perceptions and attitudes towards smoking among physicians and other healthcare providers.^16,18,19,20Understanding the attitudes of health professionals towards cessation of tobacco use is an important early step in the development of a country''s comprehensive anti‐tobacco initiative. This step is especially important in countries like Indonesia, where there are few anti‐tobacco initiatives and physicians play a particularly important role as opinion leaders and role models. To understand physician''s attitudes towards tobacco, we conducted a survey of physicians to explore a range of issues including smoking behaviours, and their attitudes and clinical practices regarding smoking.     

Microbial Fuel Cell Membrane Bioreactor in Wastewater Treatment,Electricity Generation and Fouling Mitigation

Membrane bioreactors (MBR) have gained much attention due to their ability to achieve higher treatment efficiency. However, high external energy consumption in aeration for membrane fouling mitigation has been limiting their application. Microbial fuel cells (MFC) can ideally extract energy from wastewater in the form of electricity and reduce membrane fouling. Thus, the use of MFC-MBR is rapidly expanding. However, the MFC-MBR design and operation is not fully mature and further research is needed to optimize the process efficiency and enhance the applicability. This review gives an overview of recent studies on the performances of MFC-MBR systems, regarding the design and configuration of the integrated system, irrespective of whether optimization was done or not in the operating system.