Inactivation of Lactobacillus fructivorans in physiological saline and unpasteurised sake using CO2 microbubbles at ambient temperature and low pressure

The ability of carbon dioxide microbubbles (MB‐CO₂) to inactivate Lactobacillus fructivorans suspended in physiological saline and unpasteurised sake at ambient temperature and a pressure lower than 2.0 MPa was investigated. The number of L. fructivorans cells in physiological saline solution containing 15% ethanol showed a 6‐log reduction following MB‐CO₂ treatment at 40 °C and 2.0 MPa for 50 min. The effectiveness of the treatment increased concomitantly with temperature, pressure and ethanol concentration of the sample solution but was unaffected by the glucose concentration in the sample solution. Furthermore, the number of L. fructivorans cells showed a 5‐log reduction in sake after MB‐CO₂ treatment at 40°C and 2.0 MPa for 60 min. Sensory evaluation revealed no significant difference between MB‐CO₂‐treated sake and unpasteurised sake. These results indicated that MB‐CO₂ treatment was highly effective for the inactivation of L. fructivorans and might become a practical method for pasteurising sake at ambient temperature.     

静力弹塑性分析在唐山第三空间综合体工程结构抗震优化设计中的应用

利用静力弹塑性分析对拟建结构进行抗震性能设计,分析结构在地震作用下从构件到结构多层面的弹塑性性能,方法概念清楚,实施相对简单。以一框架-剪力墙高层建筑为例,利用SAP2000软件对结构进行静力弹塑性分析,评估结构的抗震性能,考察结构方案的合理性、经济性,重点关注转换构件、错层柱、底部剪力墙、连梁等关键部位的塑性发展情况,为结构设计优化提供依据。     

聚乳酸纤维与棉纤维不同混纺比对纱线力学性能的影响

文章对聚乳酸纤维的性能和发展应用进行了阐述。通过设定实验条件,对聚乳酸纤维和棉纤维不同混纺比下的拉伸性能进行测试、分析,并得出结论。     

Gene structure and regulation of alkane monooxygenases in propane-utilizing Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7

Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7 were isolated from soil samples as propane-utilizing bacteria and were found to be able to utilize various gaseous and liquid n-alkanes as carbon and energy sources. One gene cluster, M-prmABCD, and two gene clusters, P-prm1ABCD and P-prm2ABCD, were cloned from the genomes of Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7, respectively. These gene clusters are homologous to the gene cluster encoding the multicomponent propane monooxygenase (prmABCD) of Gordonia sp. TY-5. The expression of prm gene clusters in Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7 was shown to be induced by gaseous n-alkanes (C2-C4) except methane, suggesting that the products of these genes are involved in gaseous n-alkane oxidation. Homologous genes for an alkane hydroxylase system (alk system) involved in liquid n-alkane oxidation were also cloned from the genomic DNA of Mycobacterium sp. TY-6. The alk gene cluster was transcribed in response to liquid n-alkanes (C11-C15). These results indicate that Mycobacterium sp. TY-6 has two distinct gene clusters for multicomponent monooxygenases involved in alkane oxidation. Whole-cell reactions revealed that propane is oxidized to 1-propanol through terminal oxidation in Mycobacterium sp. TY-6 and that propane is oxidized to 1-propanol and 2-propanol through both terminal and subterminal oxidations in Pseudonocardia sp. TY-7. This study reveals the diversity of propane metabolism present in microorganisms.     

Electronically tunable current-mode active-only biquadratic filter

This paper presents a realization of current-mode active-only filter. The proposed filter is constructed employing operational amplifiers and operational transconductance amplifiers (OTAs). The circuit can realize biquadratic transfer function, and the circuit characteristics can be electronically tuned through adjusting the transconductance gains of the OTAs. An example is given together with simulated result by PSPICE. The circuit configuration is very suitable for implementation in both bipolar or CMOS technologies.     

Applicability of the variable-compliance-type constitutive equation to rock breakage by excavation machinery

Force (penetration resistance)-penetration curves have a very important role for accurately predicting the performance of excavation machinery. The simplest model to represent the bit-rock interaction is a linear spring, in which the spring constant has been determined experimentally, but it is difficult to find a relationship between this and the physical properties of the rock. In the present study, a variable-compliance-type constitutive equation proposed on the basis of experimental data was used to model force-penetration curves instead of the conventional linear springs. Simulations were carried out to estimate penetration-time and force-time curves for four excavation machines, a rock drill, large rock hammer, roadheader, and tunnel boring machine. In all cases, force increases linearly at first and soon reaches a peak value that depends on the parameters in the constitutive equation. Thereafter, the force rapidly decreases. The calculated results are considered to be reasonable and consistent with the measured data, qualitatively. The proposed method can be applied to more realistic and sophisticated simulations combined with the finite element method (FEM) or other appropriate calculation methods.     

The compositions of metastable phase precipitates observed at peak hardness condition in an Al-Mg-Si alloy

The metastable-phase precipitates which appear at the peak condition of hardness in an Al-0.83 at%Mg-0.4 at%Si alloy were investigated, using a combination of Vickers microhardness tests, DSC calorimetry, and field-emission STEM observations with EDX analyses. EDX and elemental mapping revealed that both Si-rich and Mg-Si precipitates with needle-shapes were present. EDX analysis showed that needle-shaped β″precipitates protruding from the specimen foils were composed mainly of Si. The present results on structures, compositions and thermal stabilities of the precipitates suggest that Si-rich precipitates co-exist with complex Mg-Si precipitates also of needle-shape.