振兴我国天然气工业研究报告之一——振兴天然气工业必须走社会主义商品经济的道路

我国天然气工业的发展与国民经济的需要不相适应,虽然可以提出许多原因,而根本原因是没有真正承认天然气工业也是社会主义商品经济的一个产业部门,没有给予天然气企业以真正的商品生产者、经营者的地位。振兴天然气工业,必须走商品经济的道路。     

A structure model and growth mechanism for novel carbon nanotubes

The growth of carbon nanotubes from catalytic thermal decomposition of acetylene on fine iron particles has been studied. Electron microscopic images of the carbon nanotubes as formed and after annealing treatment are presented. Besides the ordinary carbon nanotubes which have been reported (S. Iijima, Nature, 354 (1991) 56), we have found, at first time, two other new kinds of carbon nanotubes: one is straight or curved nanotube with many irregular multi-layered diaphragms in the hollow core, in particular, the fringes of the wall of the tubes are not parallel to the axis of the tube; another one has many regular diaphragms (bamboo-like) which keep almost constant distance with each other. A model that postulates two steps growth of nanotubes from catalyst particles is proposed to explain the microstructure of the novel carbon nanotubes.     

The Recovered Charge Characteristics of High Power Thyristors

The recovery characteristics of high power thyristors and diodes becomes increasingly important to the circuit designer as devices are made larger and faster. This paper considers various types of recovery as well as some important circuit influences on the recovery characteristics of power devices. Low and high frequency device data are presented for a number of different circuit conditions. The effects of spreading velocity, peak current during conduction, conduction pulsewidth, and commutating di/dt are considered. A new method for recovered charge data presentation is shown and some practical test circuit design considerations are discussed.     

The Effect of the Rolling Mode on the Recrystallization Behavior of 2090 Al- Li Alloy

As- received 2090 Al- Li hot- rolled plate was homogenized at 482 °C for 10 h and cold worked to 95% reduction in thickness. The rolling modes were varied. One group of samples was rolled longitudinally parallel to the hot- rolling direction, the second transversely to the rolling direction, the third at 45° to the rolling direction, and the fourth in all three modes. All four groups were subsequently annealed at 456 °C for 24 h. The effect of varying the rolling mode on the ductility and strength was studied by examining the kinetics of softening as a function of the annealing time. All the groups recrystallized in less than 1 h with a coarse, elongated grain structure. Although the strengths of the different groups were similar, the ductilities varied significantly.     

(S)-(+)-γ-苄氧基甲基-γ-丁内酯的合成研究

以Ｌ 谷氨酸为原料,首先在－５～０℃条件下重氮化,随后常温内酯化,然后在对甲苯磺酸催化下于苯中回流进行酯化,用硼氢化钠在常温下还原,最后用氧化银作为碱发生常温威廉逊（Ｗｉｌｉａｍｓｏｎ）醚化反应,以３２３％的总产率合成了标题化合物。     

Fractal-based algorithmic design of Chinese ice-ray lattices

Chinese ice-ray lattices are perhaps one of the earliest and controlled designs of asymmetric and complex patterns applied as a traditional motif in windows. Such intricate and complex designs developed centuries back have created an evident curiosity to explore its underlying geometric rules. Some scholars used the Shape Grammar as a tool to explain and recreate similar patterns. The previous studies conceive the ice-ray lattice design as the iterative subdivisions of a polygon. However, they missed explaining this geometric quality through the discussion of fractal geometry, which can explain the shapes consuming self-similar or self-affine repetitions of itself at different scales. As a novel approach, this paper analytically focuses on the fractal characters of ice-ray lattice designs and uses fractal geometry as a unique tool for generating different types of ice-ray lattices. The significance of this study is the demonstration of the efficacy of fractal geometry and the simple geometric rule of IFS for analyzing and algorithmically modeling complex lattices and cracked-like patterns.     

Kinetics of the peritectic phase transformation: In-situ measurements and phase field modeling

An experimental study has been conducted into the role of cooling rate on the kinetics of the peritectic phase transformation in a Fe-C alloy. The interfacial growth velocities of the peritectic phase transformation were measured in situ for cooling rates of 100, 50, and 10 K/min. In-situ observations were obtained using high-temperature laser scanning confocal microscopy (HTLSCM) in a concentric solidification configuration. The experimentally measured interface velocities of the liquid/austenite (L/γ) and austenite/delta-ferrite (γ/δ) interphase boundaries were observed to increase with higher cooling rates. A unique finding of this study was that as the cooling rate increased, there was a transition point where the L/γ interface propagated at a higher velocity than the γ/δ interface, contrary to the findings of previous researchers. Phase field modeling was conducted using a commercial multicomponent, multiphase package. Good correlation was obtained between model predictions and experimental observations in absolute values of interface velocities and the effect of cooling rate. Analysis of the simulated microsegregation in front of the L/γ and γ/δ interfaces as a function of cooling rate revealed the importance of solute pileup. This microsegregation plays a pivotal role in the propagation of interfaces; thus, earlier modeling work in which complete diffusion in the liquid phase was assumed cannot fully describe the rate of propagation of the L/γ and δ/γ interfaces during the course of the peritectic transformation.     

Headspace fingerprinting as an untargeted approach to compare novel and traditional processing technologies: A case-study on orange juice pasteurisation

As a rule, previous studies have generally addressed the comparison of novel and traditional processing technologies by a targeted approach, in the sense that only the impact on specific quality attributes is investigated. By contrast, this work focused on an untargeted strategy, in order to take into account unexpected and unintended effects of (novel) processing, and to possibly uncover unknown compounds resulting from alternative processing. The potential of headspace GC–MS fingerprinting was explored as a tool to compare the impact of thermal, high pressure (HP) and pulsed electric field (PEF) processing for mild pasteurisation of orange juice. This study demonstrated that when processing conditions are selected based on equivalent microbial safety, the impact of heat, HP and PEF pasteurisation on the volatile profile of orange juice can be considered comparable. During refrigerated storage, however, indirect impact differences were revealed, which were attributed to differences in degree of enzyme inactivation.     

Disturbance‐mediated Cyanobacterial Harmful Algal Bloom (CHAB) formation in a small Ohio reservoir

Cyanobacterial Harmful Algal Blooms (CHABs) in lentic waterbodies are becoming increasingly common because of climate change, changes in water usage and eutrophication. This study provides observational evidence that CHAB formation in a small Ohio reservoir (Lake Hope) is associated with metalimnetic disturbance during the summer months. Disturbance via lotic interflow may result in the appearance of CHABs in lentic habitats, with cyanobacterial maxima in the metalimnion.