Effects of transglutaminase-induced cross-linking on properties of fish gelatin–nanoclay composite film

A nanoclay composite film was produced using warm water fish gelatin as a base material and its physical, mechanical, and molecular weight change properties were observed after treatment with microbial transglutaminase. The viscosity of the MTGase-treated gelatin solution (2% w/w) increased from 86.25 ± 1.77 (0 min) to 243 ± 12.37 cp (80 min). SDS–PAGE results indicated that the molecular weight of fish gelatin solutions increased after treatment with microbial transglutaminase. Tensile strength decreased from 61.60 ± 1.77 (0 min) to 56.42 ± 2.40 MPa (30 min), while E% increased from 13.94 ± 5.09 (0 min) to 15.78 ± 5.97% (30 min) at 2% (w/w) MTGase concentration. The oxygen permeability and water vapour permeability did not change as a function of treatment time at 2% (w/w) MTGase concentration. The incorporation of nanoclay inhibited the increase of oxygen permeability. Film colour values (L, a, and b) did not change, but haze values increased from 5.24 ± 0.40 (0 min) to 6.44 ± 0.94 (50 min). XRD and TEM results suggested that the nanoclay was exfoliated in fish gelatin film.     

Organocatalytic Enantioselective Michael‐Addition of Malonic Acid Half‐Thioesters to β‐Nitroolefins: From Mimicry of Polyketide Synthases to Scalable Synthesis of γ‐Amino Acids

Highly enantioselective biomimetic Michael addition reactions of malonic acid half thioesters (MAHTs) to a variety of nitroolefins, affording the optically active γ‐amino acid precursors, were developed by employing the Cinchona‐based squaramides (up to >99% ee). Remarkably, this biomimetic process is enantioconvergent, a highly desirable feature of a catalytic asymmetric reaction, whereby E/Z‐isomers of the nitroolefins afford the same product enantiomer. The synthetic utility of this organocatalytic protocol was also demonstrated in the formal synthesis of pharmaceutically important γ‐amino acids such as baclofen. Moreover, a quantum chemical analysis of the catalyst‐substrate complexes is shown to give a detailed and instrumental insight into the origin of the observed catalytic activity.     

Protein nanopatterns and biosensors using gold binding polypeptide as a fusion partner

An efficient strategy for immobilizing proteins on a gold surface was developed by employing the gold binding polypeptide (GBP) as a fusion partner. Using the enhanced green fluorescent protein (EGFP), severe acute respiratory syndrome coronavirus (SARS-CoV) envelope protein (SCVme), and core streptavidin (cSA) of Streptomyces avidinii as model proteins, specific immobilization of the GBP-fusion proteins onto the gold nanoparticles and generation of protein nanopatterns on the bare gold surface were demonstrated. The GBP-fused SCVme bound to gold nanoparticles successfully interacted with its antibody and showed changes in absorbance and color, allowing efficient diagnosis of SARS-CoV. The fusion proteins could be successfully immobilized on the gold surface by nanopatterning and microcontact printing as examined by atomic force microscopy and surface plasmon resonance analysis. The poly(dimethylsiloxane) microfluidic channels were created on the gold surface and were used for antigen-antibody and DNA-DNA interaction studies. Specific immobilization of GBP-EGFP fusion protein and its interaction with the antibody in the microchannels could be demonstrated. By immobilizing the DNA probe through the use of GBP-fused cSA, specific hybridization of the target DNA prepared from Salmonella could also be achieved. The GBP-fusion method allows immobilization of proteins onto the gold surface without surface modification and in bioactive forms suitable for studying protein-protein, DNA-DNA, and other biomolecular interaction studies. Furthermore, these studies can be carried out in a microfluidic system, which allows high-throughput analysis of biomolecular interactions.     

Production of hydrogen by autothermal reforming of propane over Ni/delta-Al2O3

The performance of Ni/delta-Al2O3 catalyst in propane autothermal reforming (ATR) for hydrogen production was investigated in the present study. The catalysts were characterized using XRD, TEM, and SEM. The activity of the Ni/delta-Al2O3 catalyst manufactured by the water-alcohol method was better than those of the catalysts manufactured by the impregnation and chemical reduction methods. The Ni/delta-Al2O3 catalysts were modified by the addition of promoters such as Mg, La, Ce, and Co, in order to improve their stability and yield. Hydrogen production was the largest for the Ni-Co-CeO2/Al2O3, catalyst.     

Ta2O5-Incorporated WO3 nanocomposite film for improved electrochromic performance in an acidic condition

We report electrochromic and electrochemical properties of a WO3-Ta2O5 nanocomposite electrode that was fabricated from co-sputtering. Transmission electron microscopy (TEM) images of the WO3-Ta20 nanocomposite electrode revealed that morphology of the WO3 film was changed by incorporation of Ta2O5 nanoparticles, and their chemical states were confirmed to be W6+ and Ta5+ oxides from X-ray photoelectron spectroscopy (XPS). The introduction of Ta2O5 to the WO3 film played a role in alleviating surface roughness increase during continuous potential cycling; whereas the surface roughness of the WO3 film was increased from ca. 3.0 nm to ca. 13.4 nm after 400 cycles, the roughness increase on the WO3-Ta2O5 was significantly reduced to 4.2 nm after 400 cycles, as investigated by atomic force microscopy (AFM). This improvement of the stability by adding Ta2O5 may be responsible for the enhanced electrochemical and optical properties over long-term cycling with the WO3-Ta2O5 nanocomposite electrode.     

Hydroxyapatite (HA) bone scaffolds with controlled macrochannel pores

Hydroxyapatite (HA) macrochanneled porous scaffolds, with a controlled pore structure, were fabricated via a combination of the extrusion and lamination processes. The scaffold was architectured by aligning and laminating the extruded HA and carbon filaments. The macrochannel pores were formed by removing the carbon filaments after thermal treatments (binder removal and sintering). The porosity of the scaffolds was varied between 48 and 73% with a controlled pore size of ∼450 μm, by adjusting the fractions of HA and carbon filaments. As the porosity was increased from 48 to 73%, the compressive strength decreased from 11.5 to 3.2 MPa. However, the osteoblast-like cell responses on the scaffold, such as the proliferation rate and alkaline phosphatase (ALP) activity, were significantly enhanced as the porosity was increased.     

Simulation of Ca2+-activated Cl- current of cardiomyocytes in rabbit pulmonary vein: implications of subsarcolemmal Ca2+ dynamics

In recent studies, we recorded transiently activated outward currents by the application of three-step voltage pulses to induce a reverse mode of Na+-Ca2+ exchange (NCX). We found that these currents were mediated by a Ca2+-activated Cl- current. Based on the recent reports describing the atrial Ca2+ transients, the Ca2+ transient at the subsarcolemmal space was initiated and then diffused into the cytosolic space. Because the myocardium in the pulmonary vein is an extension of the atrium, the Ca2+-activated Cl- current may reflect the subsarcolemmal Ca2+ dynamics. We tried to predict the subsarcolemmal Ca2+ dynamics by simulating these current traces. According to recent reports on the geometry of atrial myocytes, we assumed that there were three compartments of sarcoplasmic reticulum (SR): a network SR, a junctional SR and a central SR. Based on these structures, we also divided the cytosolic space into three compartments: the junctional, subsarcolemmal and cytosolic spaces. Geometry information and cellular capacitance suggested that there were essentially no T-tubules in these cells. The basic physical data, such as the compartmental volumes, the diffusion coefficients and the stability coefficients of the Ca2+ buffers, were obtained from the literature. In the simulation, we incorporated the NCX, the L-type Ca2+ channel, the rapid activating outward rectifier K+ channel, the Na+-K+ pump, the SR Ca2+-pump, the ryanodine receptor, the Ca2+-activated Cl- channel and the dynamics of Na+, K+, Ca2+ and Cl-. In these conditions, we could successfully reconstruct the Ca2+-activated Cl- currents. The simulation allowed estimation of the Ca2+ dynamics of each compartment and the distribution of the Ca2+-activated Cl- channel and the NCX in the sarcolemma on the junctional or subsarcolemmal space.     

Spray characteristics of the rotating fuel injection system of a micro-jet engine

In micro-turbojet engines with less than 350 kW power, it is not easy to find a suitable fuel injector with good spray quality. However, the rotating fuel injection system can potentially provide high atomization quality without the high-pressure fuel pump through the centrifugal forces of the engine shaft. With this motivation, a very small rotating fuel injector with 40 mm diameter is designed for the micro-turbo jet engine. It is directly linked to a high-speed rotational spindle capable of a speed up to 100,000 rpm. The droplet size, velocity, and spray distribution from the PDPA (Phase Doppler Particle Analyzer) system are measured. The spray is also visualized by a high-speed camera. The test results show that the length of liquid column from injection orifice is controlled by the rotational speeds and that SMD (Sauter Mean Diameter) is decreased with increasing rotational speeds. At a rotational speed of 73.3 m/s (35,000 rpm), SMD is lower than 60 μm at the entirety of the measuring space in the case of Type 2 (injection orifice diameter of 1.5 mm) and Type 3 (injection orifice diameter of 2.2 mm). Therefore, conceptually, it is possible to apply this small rotating fuel injection system to the micro-turbojet engine combustor.     

A new bifunctional topography and current probe for scanning force microscope testing of integrated circuits

A new probe for scanning force microscope testing of ntegrated ircuits (IC) was developed enabling both investigation of topography and contactless current detection in conducting lines via evaluation of the magnetic field due to the currents by means of an anisotropic agneto- esistive (AMR) sensor. First measurements of the topography and the current detection down to 10 μA with a frequency of 1 kHz are shown on a test structure containing 15 μm and 4 μm wide conducting lines. These promising results point out an application for advanced function and failure analysis of integrated circuits in the near future.