A thermoresistant mutant of ribonuclease T1 having three disulfide bonds

Molecular-dynamic calculations predict that, if Tyr24 and Asn84are each replaced by a Cys residue, it should be possible toform a third disulfide bond in ribonuclease T1 (RNase T1) betweenthese residues, with only minimal conformational changes atthe catalytic site. The gene encoding such a mutant variantof RNase T1 (Tyr24 – Cys24, Asn84 – Cys84) was constructedby the cassette mutagenesis method using a chemically synthesizedgene. In order to reduce the toxic effect of the mutant enzyme(RNase T1S) on an Escherichia coli host, we arranged for theprotein to be secreted into the periplasmic space by using avector that harbors a gene for an alkaline phosphatase signalpeptide under the control of the trp promoter. The nucleolyticactivity of RNase T1S toward pGpC was approximately the sameas that of RNase T1 at 37°C (pH 7.5). Moreover, at 55°C,RNase T1S retained nearly 70% of its activity while the activityof the wild-type enzyme was reduced to <10%. RNase T1S wasalso more resistant to denaturation by urea than the wild-typeenzyme. However, unlike RNase T1, RNase T1S was irreversiblyand almost totally inactivated by boiling at 100°C for 15min.     

非吸湿多孔物料板块等温干燥速度的简捷算法

通过下列处理导出了非吸湿多孔物料板块等温干燥速度的简捷算法:(1)利用水分传递系数恒定的近似,通过解析传质偏微分方程得到表示干燥速度与平均湿含量关系的方程组;(2)把该方程组外推用于水传质系数可变的体系。该方法无需确定水传质系数与湿含量的关系,仅根据一条测定曲线即可预测任何等温干燥条件下的干燥速度曲线。用新的简捷算法计算的干燥速度曲线与偏微分方程的直接数值解吻合很好。     

Efficient cleavage by {alpha}-thrombin of a recombinant fused protein which contains insulin-like growth factor I

The gene for insulin-like growth factor I (IGF-I) was constructedfrom chemically synthesized deoxyoligonucleotides and expressedin Escherichia coli, under the control of a trp promoter, asa set of fusion proteins which were connected with a portionof human growth hormone through the recognition sequence fora sequence-specific protease, either blood coagulation factorXa or -thrombin. Upon induction with 3-indoleacrylic acid, fusionproteins accumulated with a yield of 10–30% of the totalprotein. A fusion protein connected through a tetradecapeptide(Asp-Asp-Pro-Pro-Thr-Val-Glu-Leu-Gln-Gly-Leu-Val-Pro-Arg) wasefficiently and correctly cleaved by -thrombin, and the purifiedIGF-I possessed somatomedin-like activity, as determined bythe enhancement of sulfation of glycosaminoglycans in culturedcostal chondrocytes from rabbits.     

In vitro and in vivo antimicrobial properties of silver-containing hydroxyapatite prepared via ultrasonic spray pyrolysis route

Hydroxyapatite (HAp), with its high biocompatibility and osteoconductivity, readily absorbs proteins, amino acids and other substances, which in turn favor the adsorption and colonization of bacteria. To prevent bacterial growth and biofilm formation on HAp discs, silver-containing (1–20 mol%) HAp (Ag-HAp) powders were synthesized using an ultrasonic spray pyrolysis (USSP) technique. The X-ray diffraction (XRD) peaks were very broad, indicating low crystallinity, and this induced the release of Ag⁺ ions from Ag-HAp powders. In addition, a gradual increase in Ca^2 + ion release was observed. These results suggest that dissolution of Ca^2 + ion in Ag-HAp triggered the release of Ag⁺ ions.The antimicrobial efficacy of Ag-HAp disc was tested against Staphylococcus aureus. Samples with Ag contents of more than 5 mol% were found to be highly effective against bacterial colonization and biofilm formation in vitro. In vivo antibacterial tests using bioluminescent strains also showed reductions in the viability of bacteria with Ag-HAp (5 mol%) discs. Biocompatibility tests using a modified Transwell® insert method showed that Ag-HAp (5 mol%) discs have negative effects on osteoblast proliferation. These results indicate that Ag-HAp (5 mol%) has effective antibacterial activity and good biocompatibility both in vitro and in vivo together with good biocompatibility, thus confirming its utility as a bactericidal material.     

Oenothein B Suppresses Lipopolysaccharide (LPS)-Induced Inflammation in the Mouse Brain

Oenothein B has been recently evaluated for its ability to affect inflammatory responses in peripheral tissues. In this study, we examined its effect on the damage to the central nervous system due to systemic inflammation. For this purpose, ICR mice were injected with an intraperitoneal (i.p.) dose of lipopolysaccharide (LPS; 1 mg/kg mouse). When oenothein B was administered per os (p.o.), it suppressed (1) LPS-induced abnormal behavior in open field; (2) LPS-induced microglial activation in the hippocampus and striatum; and (3) LPS-induced cyclooxygenase (COX)-2 production in the hippocampus and striatum of these mice. These results suggest that oenothein B had the ability to reduce neuroinflammation in the brain during systemic inflammation.     

HEAT TRANSFER IN A CONDUCTIVE-HEATING AGITATED DRYER

Abstract

The heat transfers between the heating plane and the granular materials in both the “Stationary heating-plane type” and the “Moving heating-plane type” of the conductive-heating agitated dryers were discussed mainly from the view point of the scale-up of the dryer. Under the condition of complete mixing in the bed of bulk materials, the heat transfer models proposed for both the two types of dryers can predict the heat transfer coefficients in any sizes of the dryers. However, the complete mixing is not usually accomplished in the large scale of dryer. Hence, an “Incomplete mixing model” was proposed to estimate the effect of the incompleteness of mixing on the heat transfer coefficient. In this model, the incompleteness of mixing can be apparently taken into consideration only by increasing the contact time.     

Flow guided interpolation – A GIS-based method to represent contaminant concentration distributions in groundwater

This paper introduces a new interpolation method to estimate the spatial distribution of contaminant concentrations in groundwater. The method is intended to identify areas of risks in early investigation stages when groundwater sampling data is typically scarce and available interpolation methods fail to provide reasonable results. As a consequence, the method does not only incorporate available sampling data, but also makes use of information about the groundwater flow field, in order to “guide” the interpolation with e.g. ordinary kriging or inverse distance method. The guidance includes the augmentation of available data by auxiliary point data and the segmentation of the estimated plume area into a series of sectors. The method is evaluated for several settings and different sampling data sets. Each data set reflects a specific level of field investigations at the model site, an abandoned military base in Potsdam near Berlin, Germany. The results reveal that flow guidance improves the representation of contaminant distribution for all cases examined in this study compared to “unguided” interpolation. These findings are underpinned by the results of the method’s application to real sampling data. The method especially shows its strength when data of only a few sampling points are available.     

CONVENTIONAL BASIC DESIGN FOR CONVECTION OR CONDUCTION DRYERS

The items to be considered prior to selection of dryers are explained, and a simple method for a rough estimation of dryer sizes was proposed based on data obtained from operating industrial dryers.

The equations of basic design for batch or continuous type dryers were derived. The heat was supplied to materials by convection and/or conduction. The equations were simplified to the case when the falling rate of drying is proportional to the moisture content of materials under the constant drying conditions. The heat transfer coefficient used in the equations can be determined based on the calculations or the data obtained from the experimental or industrial dryers. The equations are useful for estimating the scale-up effect of dryers.