Application of ergothioneine-rich extract from an edible mushroom Flammulina velutipes for melanosis prevention in shrimp,Penaeus monodon and Litopenaeus vannamei

This report investigated the melanosis-inhibiting properties of crude water soluble extract from the base and fruiting body waste of an edible mushroom (Flammulina velutipes) containing 9.13 ± 2.03 mg/mL 2-thiol-l-histidine-betaine (ergothioneine, ESH). Immersion of live full-grown black tiger shrimp (Penaeus monodon) and Pacific white shrimp (Litopenaeus vannamei) in a 0.5% w/v solution of mushroom extract for 1 h significantly decreased polyphenoloxidase (PPO) activity in shrimp hemolymph and expression of the prophenoloxidase (proPO) gene in hemocytes. Consequently, the development of melanosis in the treated shrimp during ice storage was prevented. Treatment with a 0.05% w/v solution of sodium sulfite and 4-hexyl-1,3-benzenediol had a similar effect. Enzyme assays showed that ESH is a non-competitive inhibitor. It is proposed that ESH possibly interacts directly with Cu²⁺ at the putative binding sites of PPO and proPO, based on copper-chelating activity analyses, thus preventing melanosis in the shrimp. This study indicated that application of ESH-rich F. velutipes mushroom extract from trimming waste is an effective natural alternative to synthetic melanosis-inhibiting agents to prevent postmortem melanosis in shrimp.     

Code performance with improved two-group interfacial area concentration correlation for one-dimensional forced convective two-phase flow simulation

In gas–liquid two-phase flow simulation for reactor safety analysis, interfacial momentum transfer in two-fluid model plays an important role in predicting void fraction. Depending on flow conditions, a shape of the two-phase interface complicatedly evolves. One of the proposed approaches is to quantify the gas–liquid interface information using interfacial area transport equation. On the other hand, a more simplified and robust approach is to classify bubbles into two-groups based on their transport characteristics and utilize constitutive equations for interfacial area concentration for each group. In this paper, interfacial drag model based on the two-group interfacial area concentration correlations is implemented into system analysis code, and void fractions were calculated for the evaluation of numerical behaviors. The present analysis includes (1) comparison of one-group and two-group relative velocity models, (2) comparison with separate effect test database, (3) uncertainty evaluation of drag coefficient, (4) numerical stability assessment in flow regime transition, and (5) transient analysis for simulating the prototypic condition. Results showed that utilization of interfacial drag force term using constitutive equations of two-group interfacial area concentration yields satisfactory void fraction calculation results. The proposed solution technique is practical and advantageous in view of reducing the computational cost and simplifying the solution scheme.     

Measurement of liquid water content in cathode gas diffusion electrode of polymer electrolyte fuel cell

Water management in cathode gas diffusion electrode (GDE) of polymer electrolyte fuel cell (PEFC) is essential for high performance operation, because liquid water condensed in porous gas diffusion layer (GDL) and catalyst layer (CL) blocks oxygen transport to active reaction sites. In this study, the average liquid water content inside the cathode GDE of a low-temperature PEFC is experimentally and quantitatively estimated by the weight measurement, and the relationship between the water accumulation rate in the cathode GDE and the cell voltage is investigated. The liquid water behavior at the cathode is also visualized using an optical diagnostic, and the effects of operating conditions and GDL structures on the water transport in the cathode GDE are discussed. It is found that the liquid water content in the cathode GDE increases remarkably after starting the fuel cell operation due to the water production at the CL. At a high current density, the cell voltage drops suddenly after starting the operation in spite of a low water content in the cathode GDE. When the GDL thickness is increased, much water accumulates near the cathode CL and the fuel cell shuts down immediately after the operation. In the final section of this paper, the structure of cathode GDL that has several grooves for water removal is proposed to prevent water flooding and improve fuel cell performance. This groove structure is effective to promote the removal of the liquid water accumulated near the active catalyst sites.     

Ammonia assimilation in Klebsiella pneumoniae F-5-2 that can utilize ammonium and nitrate ions simultaneously: purification and characterization of glutamate dehydrogenase and glutamine synthetase

The two ammonia-assimilating enzymes glutamate dehydrogenase (GDH; EC 1.4.1.4) and glutamine synthetase (GS; EC 6.3.1.2) were synthesized steadily during the cell growth of Klebsiella pneumoniae F-5-2 that can utilize NH4+ and NO3- simultaneously under aerobic conditions. The enzymes were purified to homogeneity from cell extracts and characterized. The molecular mass of the purified GDH was 300 kDa with six identical 52-kDa subunits. GDH showed its maximal activity (aminating) at pH 8.0 and was stable between pHs 5.5 and 11.5. The enzyme was NADP-specific and strongly inhibited by Ag+. It catalyzed the amination of 2-ketovalerate, 2-ketoadipate, and 2-ketobutyrate, in addition to 2-ketoglutarate. The purified GS has a molecular mass of 470 kDa with eight identical 60-kDa subunits. GS showed its maximal activity at pH 8.0 and was stable between pHs 6.0 and 7.0. The enzyme was strongly inhibited by Fe3+, Hg2+, and Cu2+.     

1/f noise behavior in semiconductor laser degradation

It is experimentally demonstrated that the increase in residual spectral linewidth during device degradation is due to an increase in 1/f noise in a multiple quantum-well (MQW) distributed-feedback (DFB) laser. The origin of 1/f noise and its influence on device characteristics is discussed and clarified by observing the degradation behavior of the spectral linewidth     

A highly repetitive sequence isolated from genomic DNA of the medaka (Oryzias latipes)

In order to investigate the relationship between various temporomandibular joint (TMJ) pain levels and the detection of high signal intensity (joint effusion) on T2 weighted magnetic resonance imaging (MRI), 19 consecutive patients who complained of unilateral painful TMJ hypomobility (closed locking) were involved in this study. All patients were clinically examined in a routine manner, and all patients rated their pain levels by a visual analogue scale and eight pain questionnaire prior MRI study. T1 and T2 weighted MRI was taken in sagittal section at unilateral affected joint side. The presence or absence of a high signal intensity spot within the TMJ compartment were judged by three examiners. The high signal intensity was detected in 10 joints, but not in 9 joints. In between these two groups, the pain ratio was calculated and compared. The data showed that there was no significant statistical correlation between pain levels and the presence of high signals. This study disclosed that the MRI detection of high signal intensity in the closed locking TMJ did not directly relate to the presence of TMJ pain nor the increased pain level. These indicate the need of further larger studies.     

Fiber volume control of composite materials by loss angle

Fiber volume plays a critical role in achieving stable mechanical and physical properties in composite structures. This study develops a method to control this parameter in carbon fiber reinforced plastics (CFRPs) on the basis of the viscoelastic character of the thermosetting matrix resin. This method relies on the loss angle δ to quantitatively control fiber volume. CFRP flat panels are manufactured at varying initiating times of pressure application depending on the δ value of the CFRP matrix resin. An analysis of the manufactured panels clearly shows that the target fiber volumes can be obtained at an appropriate δ range. Specifically, CFRP fiber volumes can be controlled through the loss angle of the matrix resin. Defining this δ range is very important for establishing mechanically and physically stable CFRP structures. POLYM. COMPOS., 37:1307–1311, 2016. © 2014 Society of Plastics Engineers     

Electrolytic reduction of U(VI) to U(IV) in acidic chloride and acidic sulfate solutions

In order to examine the applicability of the electrolytic reduction process of U(VI) (originally developed for the chloride system by PNC) to the sulfate solution system, a fundamental study was made. In this study, the concentrations of various chemical species in the catholytes were calculated at 298 K at various percentages of uranium reduction, taking the chloro-complex and sulfato-complex formation reactions of uranium into consideration. The polarization characteristics of the electrolytic reduction of uranyl chloride and uranyl sulfate were determined, using titanium and platinum cathodes, respectively, at 303 ± 1 K. In conjunction with this process, the electrical conductivity of the catholyte, the electrical resistivity of the cation exchange membrane, and the diffusion coefficient of uranyl sulfate were also determined.