Biophotofuel cell (BPFC) generating electrical power directly from aqueous solutions of biomass and its related compounds while photodecomposing and cleaning

A biophotofuel cell (BPFC) generating electrical power directly from aqueous solutions of biomass and its related compounds with simultaneous photodecomposition and cleaning was investigated. The BPFC had a nanoporous TiO₂ photoanode and an O₂-reducing cathode. As long as the compounds were either liquid or water-soluble they were photodecomposed and generated electrical power simultaneously. Various biomasses and related compounds such as glucose, amino acids, polysaccharides, proteins, lignin derivatives, cellulose derivatives and some polymers were investigated in the BPFC. Glucose was photodecomposed almost completely into CO₂ under O₂ within 20 h while generating electrical power. The incident photon-to-current conversion efficiency (IPCE) value of a 0.5 M glucose solution in the BPFC under O₂ was 29% based on the incident monochromatic light at 350 nm (intensity 3.6 mW cm⁻²). A glycine aqueous solution could be decomposed photochemically into CO₂/N₂ in a nearly stoichiometric 4:1 (CO₂:N₂) molar ratio. The photodecomposition yield of 0.01 wt% lignosulfonic acid sodium salt was 86.5% in 24 h as estimated from the CO₂ evolved. The cellulose (sulfate) gave similar BPFC characteristics under air as under 1 atm O₂. Among the compounds the highest V_oc (open circuit voltage) value was 0.90 V for glutamic acid and phenylalanine.     

Novel single-stage second-order structure for low-pass wide-band low-power continuous-time filters

A novel single-stage second-order structure for Gm-C filters is presented. It allows ample reduction in hardware and thus power consumption. Moreover, due to exploiting otherwise parasitic poles, the structure allows much higher bandwidth than in conventional designs, be achieved. To verify effectiveness of new concept, and based on the new approach to implement second-order stages, a third-order and a fifth-order continuous-time low-pass filters were implemented. The filters fabricated in a CMOS process, achieved more than 430 MHz, bandwidth and less than THD for a 400 mV_p–p 100 MHz input signal. All these accomplished with a factor of about four reduction in hardware and power. The bandwidth, output voltage swing, and dynamic range are far larger than those of any other CMOS low-pass filters thus far reported, which have bandwidth higher than 100 MHz.     

Improved optical and electrical characteristics of free-standing GaN substrates by chemical polishing utilizing photo-electrochemical method

The optical and electrical properties of GaN(0001) surfaces treated by a novel chemical polishing method are described. Scanning microscopic photoluminescence images reveal that the polished GaN surface shows improved luminescence properties compared to the untreated surface. Current-voltage measurements of Schottky barriers formed using the GaN substrates show that the polished GaN surface has a lower reverse leakage current, and that the barrier height and ideality factor are improved after the polishing treatment.     

Mechanical tuning of molecular machines for nucleotide recognition at the air-water interface

Molecular machines embedded in a Langmuir monolayer at the air-water interface can be operated by application of lateral pressure. As part of the challenge associated with versatile sensing of biologically important substances, we here demonstrate discrimination of nucleotides by applying a cholesterol-armed-triazacyclononane host molecule. This molecular machine can discriminate ribonucleotides based on a twofold to tenfold difference in binding constants under optimized conditions including accompanying ions in the subphase and lateral surface pressures of its Langmuir monolayer. The concept of mechanical tuning of the host structure for optimization of molecular recognition should become a novel methodology in bio-related nanotechnology as an alternative to traditional strategies based on increasingly complex and inconvenient molecular design strategies.     

Strength and creep behavior of geomaterials for building with tannin addition

A clay mined in Djénné (Mali) was used to elaborate geomaterials, with tannins addition from Parkia biglobosa pods (Néré). The compressed blocks of clay–sand mixtures show a composite microstructure. The clay contains significant quantities of kaolinite, illite, pyrophyllite, quartz and iron minerals as goethite and ferrihydrite. Quantitative mineralogical composition was assessed by X-ray diffraction and DTA/TG analyses. When tannin extract is added, the formation of a chemical complex with clay–iron hydroxides is evidenced by IR spectroscopy, which reveals specific bands. The compressive strength and creep behavior under 0.2 MPa during 20 days evidence different behaviors depending on humidity and tannin contents. Creep curves exhibit successive stages which can be described by the Granger model. The multi stage creep is explained by the visco-plastic behavior of clay constrained between large sand grains, where local and delayed deformation may occur with micro-cracking. Tannin addition has proved to increase the macroscopic strength, and reduce micro-cracking.     

Development of a device for dynamical measurement of the load on casting and the contraction of the casting in a sand mold during cooling

To predict and control the residual stress present in sand castings manufactured via CAE (Computer Aided Engineering), the mechanical interaction between the casting and the sand mold during cooling must be determined experimentally. A device was developed in this study to determine the load on the casting caused by the resistance of the mold and the contraction of the casting during cooling. Our device consists of two modules that work simultaneously: a module containing a load cell, for measuring the load on the casting during cooling and a module containing an LVDT (Linear Variable Differential Transformer) for measuring the contraction of the casting during cooling. In performance verification testing, the device enabled the simultaneous measurement of the load on the sand casting and the contraction of the casting. This measurement was performed dynamically during the cooling process. Additionally, for the case where the contraction of the casting was hindered by the sand mold, the permanent deformation of the casting after shake out (which leads to residual stress in the casting) was successfully measured using our device.     

Strength evaluation of unidirectional carbon fiber-reinforced plastic laminates based on tension–compression biaxial stress tests

Biaxial stress tests of carbon fiber-reinforced plastic (CFRP) laminates were performed to investigate failure criteria under biaxial loads. Specimens of unidirectional CFRP laminates were subjected to a tensile load in the longitudinal fiber direction and a compressive load in the transverse fiber direction. An exclusive jig was used to perform biaxial stress tests with a commonly used single-axis testing machine. Measurements were obtained by controlling the displacement ratio between compressive and tensile displacements. The critical tensile and compressive stresses were then calculated using a constitutive equation. The critical longitudinal tensile stress markedly dropped with increasing the compressive load. The failure criteria of the biaxial stress tests were expressed as the ellipse, of which the major and minor axes were the longitudinal tensile/transverse compressive strengths or fracture strains, respectively. Scanning electron microscope observations suggest that fiber/matrix interfacial debonding due to the compressive load could decrease the critical longitudinal tensile stress.     

Immunoelectron Microscopic Characterization of Vasopressin-Producing Neurons in the Hypothalamo-Pituitary Axis of Non-Human Primates by Use of Formaldehyde-Fixed Tissues Stored at −25 °C for Several Years

Translational research often requires the testing of experimental therapies in primates, but research in non-human primates is now stringently controlled by law around the world. Tissues fixed in formaldehyde without glutaraldehyde have been thought to be inappropriate for use in electron microscopic analysis, particularly those of the brain. Here we report the immunoelectron microscopic characterization of arginine vasopressin (AVP)-producing neurons in macaque hypothalamo-pituitary axis tissues fixed by perfusion with 4% formaldehyde and stored at −25 °C for several years (4–6 years). The size difference of dense-cored vesicles between magnocellular and parvocellular AVP neurons was detectable in their cell bodies and perivascular nerve endings located, respectively, in the posterior pituitary and median eminence. Furthermore, glutamate and the vesicular glutamate transporter 2 could be colocalized with AVP in perivascular nerve endings of both the posterior pituitary and the external layer of the median eminence, suggesting that both magnocellular and parvocellular AVP neurons are glutamatergic in primates. Both ultrastructure and immunoreactivity can therefore be sufficiently preserved in macaque brain tissues stored long-term, initially for light microscopy. Taken together, these results suggest that this methodology could be applied to the human post-mortem brain and be very useful in translational research.