Immobilization of Escherichia coli cells using porous support particles coated with cationic polymers

The technique of cell immobilization using porous biomass support particles (BSPs), which is attractive from the point of view of simplicity and convenience, relies on the inherent ability of adhesive cells, as a consequence of their growth, to form films around the support material or the ability of flocculent cells to create flocs within the porous structure. In the present study, the immobilization of Escherichia coli cells using BSPs was investigated in shake-flask culture. The density of the cells immobilized within the BSPs was evaluated by measuring their intracellular lactate dehydrogenase (LDH) activity. Since E. coli K12 cells were not successfully retained within reticulated polyvinyl formal (PVF) resin BSPs with matrices of relatively small pores (pore diameter 60 microm), coating the surface of the BSPs with various polymers was examined as a way of promoting cell attachment. When positively charged polyamino acids such as poly-L-lysine, poly-L-arginine, poly-L-histidine, and poly-L-ornithine were adsorbed onto the particle surface, they were found to increase the immobilized cell density, while neutral and negatively charged polyamino acids including poly-L-asparagine and poly-L-glutamic acid were not effective. These results indicate that E. coli cells can be efficiently immobilized in PVF resin BSPs by electrostatic interaction between the negatively charged ions of the cell surface and the positively charged polymers adsorbed onto the BSP surface. A significantly high immobilized cell density was also achieved by coating the surface of the BSPs with the synthetic polymeric amine polyethyleneimine.     

Electrochemical oxidation for low concentration of aniline in neutral pH medium: application to the removal of aniline based on the electrochemical polymerization on a carbon fiber

Aniline, which causes serious environmental problems, was electrochemically treated and thereby removed from aqueous solution. This method demonstrated herein is based on the formation of polyaniline at an electrode surface by electrochemical oxidation. Initially, the electrode behavior of aniline at several conditions was investigated on a platinum, glassy carbon (GC), and carbon fiber (CF) electrode using voltammetric techniques. On the platinum electrode, aniline did not polymerize at low concentrations. However, electropolymerization of aniline was observed on both the GC and CF electrodes even at low concentrations in neutral pH solutions. The removal of aniline was carried out using a CF bundle with a large surface area. High removal efficiency for aniline was obtained by applying potentials greater than 0.8 V. Although generation of p-benzoquinone as a byproduct was observed during electrochemical treatment, its generation was suppressed by applying a potential lower than 0.9 V. The cyclic voltammograms and X-ray photoelectron spectra of the CF after the treatment for aniline solution showed that polymeric aniline existed on the CF surface. The maximum surface coverage of electropolymerized aniline was estimated to be about 1.49 x 10(-8) mol/cm2. Furthermore, the continuous treatment of aniline was demonstrated using a flow system.     

Investigation of field emission properties of nanorods formed on nanostructured laminated films

The origin of field emission of nano-crystalline diamond/carbon nanowall (ND/CNW) films prepared by DC plasma CVD has been investigated by macroscopic field emission measurements and SEM observation. We found that there is correlation between the field enhancement factors estimated from Fowler-Nordheim plots and shape parameters of the highest nanorods of ND/CNW films deposited at various deposition times. In addition, it was found that emission site densities were almost independent to the deposition time although the deposition time changed the total nanorod densities by over a factor of ten. We concluded that the origin of field emission of ND/CNW films derives from a part of the highest nanorods which mainly grow during CNW deposition.     

Hybrid White Light Emitting Diode Based on Silicon Nanocrystals

A novel design of white light emitting diodes (WLEDs) emerges to meet the growing global demand for resource sustainability while preserving health and environment. To achieve this goal, a facile method is developed for the chemical synthesis of a luminescent silicon nanocrystal (ncSi) with a large Stokes shift between absorption and emission. The WLED is prepared by a simple spin‐coating method, and contains a hybrid‐bilayer of the ncSi and luminescent polymer in its device active region. Interestingly, a well‐controlled ultrathin ncSi layer on the polymer makes possible to recombine electrons and holes in both layers, respectively. Combining red and blue‐green lights, emitted from the ncSi and the polymer layers, respectively, produces the emission of white electroluminescence. Herein, a hybrid‐WLED with a sufficiently low turn‐on voltage (3.5 V), produced by taking advantages of the large Stokes shift inherent in ncSi, is demonstrated.     

Minimum Classification Error Training Incorporating Automatic Loss Smoothness Determination

Minimum Classification Error (MCE) training, which has been widely used as one of the recent standards of discriminative training for classifiers, is characterized by a smooth sigmoidal-form classification error count loss. The smoothness of this loss function effectively increases training robustness to unseen samples, well approximates the ultimate, minimum classification error probability status, and leads to accurate classification over unseen samples. However, few rational methods have been developed for controlling the smoothness, which is often determined through many repetitions of the experimental setting; this empirical approach has been a disincentive to the increased popularization of MCE training. To alleviate this long-standing problem, we propose a new MCE training method that automatically determines loss smoothness. The proposed method is based on Parzen-estimation-based MCE re-formalization, and the loss smoothness degree is determined so that Parzen distribution can be an accurate approximation to the unknown true distribution, whose positive-domain integration corresponds to classification error probability, in one-dimensional misclassification measure space. Through systematic experiments, we show that the proposed method efficiently yields a classification accuracy that nearly matches the best accuracy obtained by the conventional, trial-and-error-mode repetitions of smoothness setting.     

Quantitative Chemical Exchange Saturation Transfer Imaging of Amide Proton Transfer Differentiates between Cerebellopontine Angle Schwannoma and Meningioma: Preliminary Results

Vestibular schwannomas are the most common tumor at the common cerebellopontine angle, followed by meningiomas. Differentiation of these tumors is critical because of the different surgical approaches required for treatment. Recent studies have demonstrated the utility of amide proton transfer (APT)-chemical exchange saturation transfer (CEST) imaging in evaluating malignant brain tumors. However, APT imaging has not been applied in benign tumors. Here, we explored the potential of APT in differentiating between schwannomas and meningiomas at the cerebellopontine angle. We retrospectively evaluated nine patients with schwannoma and nine patients with meningioma who underwent APT-CEST MRI from November 2020 to April 2022 pre-operation. All 18 tumors were histologically diagnosed. There was a significant difference in magnetization transfer ratio asymmetry (MTR_asym) values (0.033 ± 0.012 vs. 0.021 ± 0.004; p = 0.007) between the schwannoma and meningioma groups. Receiver operative curve analysis showed that MTR_asym values clearly differentiated between the schwannoma and meningioma groups. At an MTR_asym value threshold of 0.024, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTR_asym were 88.9%, 77.8%, 80.0%, and 87.5%, respectively. Our results demonstrated the ability of MTR_asym values on APT-CEST imaging to discriminate patients with schwannomas from patients with meningiomas.     

Propagation of weak pressure waves against two parallel subsonic streams

In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation, and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves. The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.     

Biodiesel fuel production from plant oil catalyzed by Rhizopus oryzae lipase in a water-containing system without an organic solvent

A new enzymatic method of synthesizing methyl esters from plant oil and methanol in a solvent-free reaction system was developed. It is anticipated that such plant oil methyl esters can be used as a biodiesel fuel in the future. Lipase from Rhizopus oryzae efficiently catalyzed the methanolysis of soybean oil in the presence of 4–30 wt% water in the starting materials; however the lipase was nearly inactive in the absence of water. The methyl ester (ME) content in the reaction mixture reached 80–90 wt% by stepwise additions of methanol to the reaction mixture. The kinetics of the reaction appears to be in accordance with the successive reaction mechanism. That is, the oil is first hydrolyzed to free fatty acids and partial glycerides, and the fatty acids produced are then esterified with methanol. Although R. oryzae lipase is considered to exhibit 1(3)-regiospecificity, a certain amount of 1,3-diglyceride was obtained during the methanolysis and hydrolysis of soybean oil by R. oryzae lipase solution. Therefore, the high ME content in the reaction mixture is probably attributable to the acyl migration from the sn-2 position to the sn-1 or sn-3 position in partial glycerides.     

Pulse energization system of electrostatic precipitator forretrofitting application

A pulser module has been developed for electrostatic precipitators for upgrading the performance of existing plants. The module is inserted between the existing DC power supply and corona electrodes. A sawtooth voltage appears on the corona electrodes at a switching frequency, including at its leading edge a transient LC oscillation with a very sharp first peak and fast-decaying amplitude. This acts as the submicrosecond pulse energization, producing very active negative streamers in uniform distribution along the entire length of corona wires of the conventional construction. The average of the sawtooth voltage produces a DC field between the corona and the collecting electrodes. This direct-coupled pulse energization indicates in present laboratory tests exactly the same collection performance as the hitherto most effective submicrosecond pulse energization using a coupling capacitor and a DC bias voltage. A specific feature of the present pulse energization system is its simplicity in construction and low initial and operating costs