A Patterned Graphene/ZnO UV Sensor Driven by Integrated Asymmetric Micro‐Supercapacitors on a Liquid Metal Patterned Foldable Paper

A foldable array of patterned graphene/ZnO nanoparticle UV sensor and asymmetric micro‐supercapacitors (AMSCs) integrated on a paper substrate with patterned liquid metal interconnections is reported. The resistor type UV sensor based on graphene/ZnO nanoparticles is patterned to be driven by the stored energy of the integrated AMSCs. The AMSC consists of MnO₂ nanoball deposited multiwalled carbon nanotubes (MWNTs) and V₂O₅ wrapped MWNTs as positive and negative electrodes, respectively. As an electrolyte, propylene carbonate‐poly(methyl methacrylate)‐LiClO₄, an organic solvent‐based gel, is used. The UV sensor and AMSCs can be easily integrated on a liquid metal, Galinstan, patterned, waterproof mineral paper and show a mechanically stable UV sensing, regardless of repetitive folding cycles. This work demonstrates a novel foldable nanomaterial based sensor system driven by integrated energy storage devices, applicable to future wearable and portable electronics.     

Design and Evaluation of Cascode GaN FET for Switching Power Conversion Systems

In this paper, we present the design and characterization analysis of a cascode GaN field‐effect transistor (FET) for switching power conversion systems. To enable normally‐off operation, a cascode GaN FET employs a low breakdown voltage (BV) enhancement‐mode Si metal‐oxide‐semiconductor FET and a high‐BV depletion‐mode (D‐mode) GaN FET. This paper demonstrates a normally‐on D‐mode GaN FET with high power density and high switching frequency, and presents a theoretical analysis of a hybrid cascode GaN FET design. A TO‐254 packaged FET provides a drain current of 6.04 A at a drain voltage of 2 V, a BV of 520 V at a drain leakage current of 250 μA, and an on‐resistance of 331 mΩ. Finally, a boost converter is used to evaluate the performance of the cascode GaN FET in power conversion applications.     

Power Semiconductor SMD Package Embedded in Multilayered Ceramic for Low Switching Loss

We propose a multilayered‐substrate‐based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost‐effective, low‐temperature co‐fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high‐temperature storage life and temperature humidity bias. At 175 °C, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 μA up to a reverse voltage of 980 V. The measured maximum reverse current (I_RM), reverse recovery time (T_rr), and reverse recovery charge (Q_rr) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and di/dt equal to 300 A/μs.     

Reversible change of wettability in poly(ɛ-caprolactone/azobenzene) honeycomb-patterned films by UV and visible light illumination

Polymer Bulletin - A new type of photosensitive poly(?-caprolactone) (PCL) composites containing 4-dimethylamino-4′-(6-hydroxy hexyloxy) azobenzene (Azo) was synthesized by in situ...     

Medium-Chain Enriched Diacylglycerol (MCE-DAG) Oil Decreases Body Fat Mass in Mice by Increasing Lipolysis and Thermogenesis in Adipose Tissue

Medium chain fatty acid (MCFA) escapes the formation of chylomicrons in the small intestine, resulting in energy expenditure through beta-oxidation. Diacylglycerol (DAG) is susceptible to oxidation rather than being stored in the adipose tissue. This study was conducted to verify the effect of MCE-DAG oil on body fat mass in vivo. Male C57BL/6 mice were randomly assigned to four groups (n = 12) as follows: (1) normal diet (18% kcal from fat), (2) canola oil as a control (40% kcal from canola oil), (3) MCE-DAG10 (10% kcal from MCE-DAG + 30% kcal from canola oil), and (4) MCE-DAG20 (20% kcal from MCE-DAG + 20% kcal from canola oil). The body weight and fat mass of MCE-DAG20 group mice were decreased relative to those of control mice (P < 0.05 and P < 0.001, respectively). Serum triacylglycerol (TAG) was decreased in both MCE-DAG10 and MCE-DAG20 groups (P < 0.01 and P < 0.05, respectively). Hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) were increased in the MCE-DAG20 group relative to the control in white adipose tissue (WAT) (P < 0.05). Uncoupling protein 1 (UCP1) was also increased in the MCE-DAG20 group relative to the control in brown adipose tissue (BAT) (P < 0.05). In summary, MCE-DAG reduced body fat mass likely by stimulating lipolysis in WAT and thermogenesis in BAT.     

Modified free-volume model for pervaporation of water/ethanol mixtures through membranes containing hydrophilic groups or ions

The free-volume model for pervaporation has been modified by considering the polar path, in order to apply the model to membranes containing hydrophilic groups. The free-volume parameters were determined by inverse gas chromatography. For the polyacrylonitrile (PAN) membrane, the transport mechanism could be analyzed only by the free-volume model; however, for a membrane containing a hydrophilic moiety, the transport properties could be interpreted by the modified model. In water/ethanol mixtures, ethanol transports through the membrane matrix, while water permeates through the polar pathways consisting of polar groups or ions and water molecules as well as through the membrane matrix. © 1995 John Wiley & Sons, Inc.     

The relationship of thermosensitive properties with structure of organophosphazenes

The lower critical solution temperature (LCST) of cyclotriphosphazenes and polyphosphazenes grafted with a hydrophilic poly(ethylene glycol) (PEG) and a hydrophobic amino acid ester (AAE) as side groups could be quantitatively correlated with the overall hydrophobicity given by linear combination of the logarithmic partition coefficients of the corresponding free PEG and AAE measured in the 1-octanol/water system. Thus the LCSTs of phosphazenes were found to be well described as a linear function of a new parameter P_t defined as linear combination of the logarithmic partition coefficients of the free side groups, K_peg and K_aae: where x is the mole fraction of PEG. The LCST of cyclotriphosphazenes has shown to be more sensitive to change in hydrophobicity than polyphosphazenes, indicating that the nature of the molecular structure plays an important role in determining their LCST. The additivity of the logarithms of the two partition coefficients for the parameter may indicate that the contribution of each constituent is independent, providing a facile method for prediction of the LCST of thermosensitive polymers.     

Functional forms and the relevance of contiguous migration in the study of migration and employment growth

Previous studies on interstate migration have dealt with total migration without decomposing it into contiguous and noncontiguous migration flows. Since migration over borders of contiguous states may merely reflect changes in residence without changes in economic activities, the use of total migration data might reduce the reliability of empirical results. In this study, a simultaneous-equation model containing two equations, one for migration and the other for employment growth, has been specified in a general form and estimated by the 2SLS method for total, contiguous and noncontiguous migration flows. Results obtained from the use of 1970 Census data show that noncontiguous migration behaves significantly different from contiguous migration, and that noncontiguous migration, rather than total migration, should be used for the study of factors affecting interstate migration. Results also indicate that the log-linear functional form commonly used in empirical studies cannot be accepted statistically.     

Effects of the tacticities of poly(vinyl alcohol) on the structure and morphology of poly(vinyl alcohol) nanowebs prepared by electrospinning

The effects of tacticities on the characteristics of poly(vinyl alcohol) (PVA) nanowebs prepared by an electrospinning technique were investigated. PVA webs composed of uniform nanofibers with syndiotactic dyad (s‐dyad) contents of 53.5 and 57.3% were successfully obtained with electrospinning. By changing processing parameters such as the initial polymer concentration, applied voltage, and tip‐to‐collector distance, we found suitable conditions for forming PVA webs with uniform nanofibers. PVAs of higher s‐dyad contents were prepared at a lower solution concentration and at a higher applied voltage because of the easy formation of syndiotactic PVA chain entanglements at a very low polymer concentration. The average diameter of the nanofibers in a PVA web with the higher s‐dyad content of 57.3% (ca. 240 nm) was thinner than that of the nanofibers in a PVA web with the lowers‐dyad content of 53.5% (ca. 270 nm). In addition, the crystallinity and thermal stability were greatly increased with an increase in the s‐dyad content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Use of two feeds in simulated moving beds for binary separations

Simulated moving bed (SMB) and Analog systems with two-feeds are proposed to increase the separation performance. Operation with both total and partial feeds is studied. When the two feeds have different compositions, the proposed SMB system often showed better performance than conventional SMB and Varicol systems and the Analog system with two-feeds typically achieved higher purities compared to the Analog for conventional SMB and Varicol when the number of tanks was increased. Partial-feed operation strategy for SMB and Analog systems with two-feeds often showed significant performance improvement compared to conventional SMB plus partial feed and Varicol plus partial feed. When the two feeds are identical, partial feed operation of the two-feed SMB becomes identical to partial feed operation of Varicol.