Commercialization of Micro-fabrication of Antenna-Coupled Transition Edge Sensor Bolometer Detectors for Studies of the Cosmic Microwave Background

We report on the development of commercially fabricated multichroic antenna-coupled transition edge sensor (TES) bolometer arrays for cosmic microwave background (CMB) polarimetry experiments. CMB polarimetry experiments have deployed instruments in stages. Stage II experiments deployed with O(1000) detectors and reported successful detection of B-mode (divergence-free) polarization pattern in the CMB. Stage III experiments have recently started observing with O(10,000) detectors with wider frequency coverage. A concept for a stage IV experiment, CMB-S4, is emerging to make a definitive measurement of CMB polarization from the ground with O(400,000) detectors. The orders of magnitude increase in detector count for CMB-S4 require a new approach in detector fabrication to increase fabrication throughput and reduce the cost. We report on collaborative efforts with two commercial micro-fabrication foundries to fabricate antenna-coupled TES bolometer detectors. The detector design is based on the sinuous antenna-coupled dichroic detector from the POLARBEAR-2 experiment. The TES bolometers showed the expected I–V response, and the RF performance agrees with the simulation. We will discuss the motivation, design consideration, fabrication processes, test results, and how industrial detector fabrication could be a path to fabricate hundreds of detector wafers for future CMB polarimetry experiments.     

Regulation of GluA1 AMPA Receptor Through PKC Phosphorylation Induced by Free Fatty Acid Derivative HUHS2002

The present study investigated the effect of 4-[4-(Z)-hept-1-enyl-phenoxy] butyric acid (HUHS2002), a newly synthesized free fatty acid derivative, on α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor responses. HUHS2002 potentiated currents through GluA1 AMPA receptors expressed in Xenopus oocytes in a bell-shaped concentration (1 nM–1 μM)-dependent manner, the maximum reaching nearly 140 % of original amplitude at 100 nM. The potentiation was significantly inhibited by GF109203X, an inhibitor of protein kinase C (PKC), but not KN-93, an inhibitor of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII). HUHS2002 had no potentiating effect on currents through mutant GluA1 AMPA receptors with replacement of Ser831, a PKC/CaMKII phosphorylation site, by Ala. In the in situ PKC assay using rat PC-12 cells, HUHS2002 significantly enhanced PKC activity, that is suppressed by GF109203X. Overall, the results of the present study show that HUHS2002 potentiates GluA1 AMPA receptor responses by activating PKC and phosphorylating the receptors at Ser831, regardless of CaMKII activation and phosphorylation.     

Degradation of cell wall materials from sweetpotato, cassava, and potato by a bacterial protopectinase and terminal sugar analysis of the resulting solubilized products

Cell wall materials (CWMs) from sweetpotato, cassava, and potato starch residues were degraded using a crude enzyme solution from the culture filtrate of a Bacillus sp. isolated from soil, Bacillus sp. M4. This organism has been found to secrete polygalacturonic acid lyase (PGL) and glycan depolymerase activities, especially arabinanase, but cellulase activity was nearly absent. Sugar analysis of the solubilized product after enzyme treatment at pH 7.0 revealed that it is mainly composed of galacturonic acid, galactose, and arabinose, the sugars found commonly in the pectin fraction. This suggested the presence of a protopectinase (PPase) activity in the culture filtrate. The presence of EDTA completely inhibited PGL but PPase activity was almost retained, suggesting that the PGL is not the primary activity responsible for pectin solubilization. The mode of action of the crude enzyme was determined by terminal sugar analysis using HPAEC-PAD after hydrolysis of the reduced products. Results revealed that galactose is the main neutral sugar at the reducing terminal of the products, although rhamnose was also present in the higher molecular weight component. This suggested that at neutral pH, the primary activity in the culture filtrate of Bacillus sp. M4 is a B-type PPase, which attacked the galactan as well as rhamnogalacturonan moieties of the protopectin, resulting in the release of a soluble pectin fraction.     

Thermal conductivity of polypropylene composites with hybrid fillers of boron nitride and vapor‐grown carbon fiber

High thermal conductivity fillers of boron nitride (BN) and vapor‐grown carbon fiber (VGCF) were used alone or incorporate to prepare polypropylene (PP) composites. The effects of filler content, particle size and shape, and single vs. hybrid BN/VGCF fillers were investigated with respect to the thermal conductivity of the PP composites. The thermal conductivity of PP/BN composites depended upon the content and particle size of the BN. Increased content and length of VGCF had the effect of increasing the thermal conductivity of the PP composites. Hybrid fillers were created with a mixture of medium‐sized BN and long‐length VGCF; hybrid BN/VGCF fillers enhanced the thermal conductivity of PP composites with a lower total content compared with PP composites containing only medium‐sized BN particles. POLYM. COMPOS., 37:936–942, 2016. © 2014 Society of Plastics Engineers     

Effect of screw rotation speed on the properties of polystyrene/organoclay nanocomposites prepared by a twin‐screw extruder

We discuss the effect of screw rotation speed on the mechanical and rheological properties and clay dispersion state of polystyrene (PS)/organoclay (clay) nanocomposites prepared by melt compounding with a counterrotating‐type twin‐screw extruder. Poly(styrene‐co‐vinyloxazolin) (OPS) was used as an additional material. The Young's modulus of the PS/OPS/clay nanocomposites showed the maximum value at a screw rotation speed of 70 rpm in this study. This implied the existence of an optimized screw rotation speed for the melt compounding of the polymer/clay nanocomposites. For PS/clay systems without the addition of OPS, the peak intensity from clay increased and the distance between clay platelets in the nanocomposites decreased with the screw rotation speed. On the other hand, inverse results were obtained for PS/OPS/clay systems. According to the transmission electron microscopy photographs, the PS/OPS/clay nanocomposite at 70 and 100 rpm had fully exfoliated clay platelets. The dynamic rheological properties of the PS/clay nanocomposites were almost the same as those of neat PS. On the other hand, the storage and loss moduli of the PS/OPS/clay nanocomposites at the same frequency were larger than those of the PS/clay system. On the whole, the bonding between clay platelets and PS was important for increasing the viscosity and elasticity in the melts of the PS/clay system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1165–1173, 2006     

Evaluation of neutron economical effect of new cladding materials in light water reactors

The present paper aims to contribute from a neutronic aspect to activities for new cladding material development for light water reactors (LWRs) that can reduce the risk of hydrogen gas explosion. Iron (Fe), nickel (Ni), titanium (Ti), niobium (Nb) and vanadium (V) are selected as possible component elements to cover a variety of new cladding materials for LWRs. The effect of larger thermal absorption cross sections of these elements than those of zirconium (Zr), together with those of silicon carbide (SiC), on the neutron economy in LWRs is evaluated by performing pin cell burnup calculations for a conventional pressurized water reactor (PWR), a low-moderation high-burnup LWR (LM-LWR) and a high-moderation high-burnup LWR (HM-LWR). As can be anticipated from the thermal cross sections, SiC has excellent neutron economy. The materials other than SiC largely decrease discharge burnup for all three types of LWRs in comparison with Zircaloy-4. Among such elements of larger thermal absorption cross section, Nb has neutron economical advantage over the other materials except SiC in softer neutron spectrum reactors such as HM-LWR in which the atomic number ratio of hydrogen to heavy metal is 6. In conventional LWRs, stainless steel of low Ni contents has the neutron economic advantage as well as Nb for cladding material. The results of the calculations are summarized for the purpose to provide reference data for new cladding material development studies, in terms of the relation between fuel enrichment and cladding thickness from the viewpoint to achieve the same discharge burnup as the Zircaloy cladding.     

Polycrystal isolation of InGaP/GaAs HBTs to reduce collectorcapacitance

InGaP/GaAs heterojunction bipolar transistors (HBTs) with polycrystalline GaAs buried under the base electrode have been fabricated using low-temperature gas-source molecular beam epitaxy on SiO₂-patterned substrates. A cutoff frequency of 120 GHz and a maximum oscillation frequency of 230 GHz were obtained for three parallel 0.7×8.5 μm HBTs. Compared to HBTs without the polycrystal, the collector capacitance was reduced by 28% and the maximum stable gain was improved by 1.2 dB due to complete carrier depletion in the polycrystal under the base electrode. These results show the high potential of the proposed HBTs for high-speed digital and broadband-amplifier applications     

Hydrogen evolution from cathodically charged titanium aluminide alloy Ti–24Al–11Nb

A Ti₃Al-based titanium aluminide alloy, Ti–24Al–11Nb, was cathodically charged with hydrogen in a 5% H₂SO₄ aqueous solution for various charging times, and the formation and dissociation of the hydride, the hydrogen evolution behavior and the total hydrogen uptake were investigated mainly by means of X-ray diffractometry and thermal desorption spectroscopy (TDS). The same kind of hydride phase as observed previously in Ti–25Al alloy (hexagonal hydride) was presumably formed in the Ti–24Al–11Nb alloy after cathodic charging. No damage, such as cracks, was induced by hydrogen charging. Two kinds of TDS peaks, one probably corresponding to hydride dissociation and the other to hydrogen dissolution in the normal lattice site, were found after longer hydrogen charging. It is suggested that niobium addition to Ti₃Al-based titanium aluminide alloy may reduce hydrogen susceptibility during cathodic charging.     

Direct deposition of two nanomaterials with the same surface charge using a liquid-liquid interface

Two negatively charged nanoparticles (SDS-coated SWCNT and polydiacetylene nanocrystals) were sequentially adsorbed onto the same water-hexane interface. The absorbed film can be transferred onto a solid substrate. Repeating the adsorption and transfer process enables assembly of the two nanoparticles in a layer-by-layer growth fashion up to three bi-layers.