Enhanced thermal properties of the solid electrolyte interphase formed on graphite in an electrolyte with fluoroethylene carbonate

The influence of fluoroethylene carbonate (FEC) on the electrochemical and thermal properties of graphite anodes is examined. The dQ/dV graph of graphite/Li cells shows that the electrochemical reduction peak of an electrolyte shifts to higher potential in the presence of FEC. The DSC results for graphite anodes cycled in FEC-containing electrolytes clearly exhibit that an exothermic peak at around 120 °C mostly disappears. It is demonstrated by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) that SEI formed by the electrochemical reduction of FEC consists of a relatively high proportion of LiF and gives low interfacial resistance for graphite/Li/Li cells.     

Mining health-risk factors using PHR similarity in a hybrid P2P network

In an era of many diseases and increased longevity, more attention has been paid to chronic diseases that require constant health care. Under this circumstance, the development of research and development (R&D) for smart-device-based constant health care has drawn great attention. With the emergence of wearable devices, personal health devices (PHDs), and smartphones, various contents for constant health care have been developed. By using these devices, the users are able to collect personal health records (PHRs) that include data such as activity amount, heart rate, stress, and blood sugar. The range of the collected PHRs can be limited depending on the equipment or the surrounding environment. To overcome this problem, it is necessary to make a comparison with similar users in a cluster. Also, it is necessary to provide a service that can analyze and visually display the collected personal-health information. In this paper, we propose the mining of health-risk factors using the PHR similarity in a hybrid P2P network. This is a method of predicting a user’s health status using similarity-based data mining, where the PHRs are employed in a hybrid P2P environment consisting of a peer, a server, and a gateway. In a hybrid P2P environment, a user receives feedback on the result of a structured-data analysis. A peer searches for a different peer and gateway through a server and exchanges information. Depending on the data type, the PHR is divided into medical health examination, self-diagnosis, and personal-health data. The medical health examination contains the personal-health data that are generated regularly by a medical institution. Self-diagnosis represents the data of mental health, pains, and fatigue that can be changed often but cannot be collected by devices. Personal-health data mean the data that can be collected by individuals in everyday life. For the PHR-data analysis, an index is given to each attribute, and preprocessing is performed after a binary-code conversion. To predict a user’s health status, the PHR data are clustered on the basis of similarity in a hybrid P2P environment. The similarity between a user’s PHR and a PHR that is searched for in the network is measured. After the measurement, an index is given to the PHR that meets the minimum similarity and the PHR is incorporated into a Similarity PHR Group. The Similarity PHR Group flexibly changes depending on a user’s PHR status and the statuses of the users who have accessed the hybrid P2P network. A representative value of the Similarity PHR Group is extracted and is then compared with the user’s PHR to judge the user’s health status. The proposed method is suitable for a smart health service for chronic diseases requiring constant care, elderly health, and aftercare. This is a user-oriented health-care and promotion service wherein a user’s health status can be predicted through the mining of the health-risk factors of PHRs.     

Transparent flexible heater based on hybrid of carbon nanotubes and silver nanowires

Transparent film heaters have attracted increasing attention due to their usefulness in a wide range of applications, such as outdoor panel displays, avionic displays, and periscope and vehicle window defrosters. So far, transparent films made of only one kind of conductive nanomaterial have been tried in the fabrication of transparent film heaters. However, since each nanomaterial has its own advantages and disadvantages, satisfying various requirements from industry has so far been almost impossible. Here, we present a high-performance transparent film heater based on a hybrid of carbon nanotubes and silver nanowires. The new hybrid film shows a marked advance in haze reduction and an improvement in the flexibility of the silver nanowire film while maintaining excellent electrical conductivity. We demonstrate sufficient temperature rise even at low voltages and long-term stability of the new film heater. The present work sheds light on the feasibility of a more advanced film heater that will satisfy growing demands for better optoelectrical properties with excellent mechanical flexibility.     

Polycrystalline diamond shaving conditioner for CMP pad conditioning

This paper investigates a new design of diamond conditioner that is made by shaping a sintered matrix of polycrystalline diamond (PCD) to form serrated blades. These blades are arranged and embedded in a predetermined groove on a substrate surface of cylinder. This newly designed diamond conditioner is referred to here as a blade diamond disk. The dressing characteristics of pad surface textures are studied by comparing them with traditional diamond conditioners, and the polishing rates of silicon dioxide are also studied. It is found that serrated blades made of polycrystalline diamond enable the manufacturer to tightly control the diamond leveling, cutter's shape and penetration angle. The height variations of the diamond tips of the blade diamond disk are significantly smaller than that of the traditional diamond disk. Experimental results reveal that the pad dressing rate of a blade diamond disk is lower than that of a conventional diamond disk. The lifetime of the pad is expected to have been prolonged, consequently lowering the cost of the CMP process. The removal rate of the oxide film is higher for the blade diamond disk than for the traditional diamond disk, and hence wafer productivity is somewhat increased.     

Off-state degradation with ac bias in PMOSFET

For the first time, the current failure of p-channel MOSFETs used for the sub-wordline driver of state-of-the-art DRAM chips was investigated during off-state switching cycles. With increasing switching speed for the sub-wordline driver, the subthreshold leakage current of p-channel MOSFETs increased, and resulted in serious stand-by current failure. The model proposed in this work suggested that the off-state degradation of p-channel MOSFETs with ac bias will intensify as the dimensions of devices decrease due to both the high electric field and the high operating frequency. The roles of various device parameters- such as gate length, gate-tab width, doping concentration at the source/drain extensions, operating temperature and operating frequency- on the degradation of p-channel MOSFETs were investigated.     

On line and under veil: Technology-facilitated communication and Saudi female experience within academia

The Saudi female population, which is characterised as sheltered, hard-to-reach and conservative, is arousing good interest globally (and nationally). Therefore, a review of literature on emerging issues surrounding Saudi female experience is timely. This article, in the form of a literature review, provides a background to and justification for a forthcoming study, which will examine how technology-facilitated communication has shaped the social–cultural pattern of Saudi female experience within academia.     

Fischer–Tropsch synthesis over a Co/SiO2 catalyst modified with Mn- and Zr under practical conditions

Fischer–Tropsch (FT) synthesis activity and the stability of a Co/SiO₂ catalyst modified with Mn- and Zr were examined under various practical conditions. Dependence of FT synthesis on reaction pressure and bench-scale FT synthesis were investigated. Evaluating catalyst lifetime during continuous FT reactions was conducted. The Co + Mn + Zr/SiO₂ catalyst exhibited relatively greater activity and stable reactivity for 168 h. Sulfur resistance of catalysts were investigated and results showed that the presence of 4 ppm H₂S drastically affected catalytic activity. The Co + Mn + Zr/SiO₂ catalyst exhibited greater activity even with H₂ presence and the sulfur poisoning rate was almost similar on both Co + Mn + Zr/SiO₂ and Co/SiO₂ catalysts.     

Effect of geometry on crashworthiness parameters of natural kenaf fibre reinforced composite hexagonal tubes

The effect of geometry on energy absorption capability and load-carrying capacity of natural kenaf fibre reinforced composite hexagonal tubes had been investigated experimentally. A series of experiments were carried out for composite hexagonal tubes with different angles from a range of 40–60° in 5° steps. This range is suitable for obtaining a regular hexagonal shape. Kenaf fibre mat form was used in this work due to several advantages such as low cost, no health risk, light weight and availability. The kenaf density was usage 0.17 g/cm³ with thickness of 4 mm. Results demonstrated that structures failed in few distinct failure modes. Precisely in progressive failure mode and fragmentation failure associated with longitudinal cracks. The composite tube with β = 60° exhibited local buckling failure mode and displayed the highest specific energy absorption capability equal to 9.2 J/g. On the other hand, new crashworthiness parameter has been introduced as catastrophic failure mode indicator (CFMI). Furthermore, typical load–deformation histories were presented and discussed.     

Piezoelectric Effects on the Shockley-Read-Hall Generation Currents in a p-n Junction

We numerically studied the correlation between the piezoelectric effect and the Shockley-Read-Hall (SRH) generation current by examining the defect states within the depletion region (space charge region, w) in a piezoelectric p-n junction system consisting of piezo (n-type: n-ZnO) and non-piezo (p-type: P3HT) parts. Through finite element method calculations, it was demonstrated that the electric potential, owing to the external compressive pressure (T_z) generating negative piezoelectric charges at the p-n interface, becomes more negative. Correspondingly, as T_z increases, so does the number of states depleted of free carriers (depletion region shifts). These observations were confirmed by the increase in the z-component of the electric field distribution and the SRH generation currents, given that current is proportional to the w (T_z).     

SO2 durability enhancement of ball milled V/TiO2 catalyst

Various experiments and analyses were performed to explore the reasons for SO₂ durability enhancement of the V/TiO₂ catalyst, which was created by the ballmill (BM) method. Compared to the BM catalyst, the raw catalyst showed low selective catalytic reduction (SCR) activation in mid/low temperature ranges. As the raw catalyst's SCR activity in low temperature range was lower than the BM catalyst's activity, the amount of unreacted NH₃ emitted was higher. However, in the presence of SO₂, the emitting amount of unreacted NH₃ was decreased. According to BET and FT-IR analysis, this phenomenon occurs due to the relatively high production of ammonium sulfate salts, which are created by unreacted ammonia and water in response to the presence of SO₂. However, the BM catalyst emits less unreacted ammonia due to its excellent SCR activity. Moreover, when the SCR experiment at each level of water concentration was performed, water adsorption to the catalyst's active site occurred less frequently. According to the XPS analysis, the BM catalyst includes a great amount of non-stoichiometric chemical species V^x+ (x ≤ 4). This means that the BM catalyst provokes less oxidation of SO₂ to SO₃. Therefore, the BM catalyst shows excellent SO₂ durability.