泥浆录井技术新进展(一)

正数十年来,地面采集的样品和计量结果为录井人员提供了洞察钻头端面条件的重要信息。通过录井采集的信息使作业者提前了解油藏潜力,甚至提前预防地层压力问题。而新型采样和分析技术,以及地面传感器设计和监测系统的进步,使录井科学正以新的面貌迈进21世纪。长期以来,泥浆录井仪一直是井场的常用设备。1939年,泥浆录井仪首次投入商用。当时这种移动实验室中仅包括咖啡壶、用于检查地层岩屑的     

Structural Analysis of CYP101C1 from Novosphingobium aromaticivorans DSM12444

CYP101C1 from Novosphingobium aromaticivorans DSM12444 is a homologue of CYP101D1 and CYP101D2 enzymes from the same bacterium and CYP101A1 from Pseudomonas putida. CYP101C1 does not bind camphor but is capable of binding and hydroxylating ionone derivatives including α‐ and β‐ionone and β‐damascone. The activity of CYP101C1 was highest with β‐damascone (k_cat=86 s^?1) but α‐ionone oxidation was the most regioselective (98 % at C3). The crystal structures of hexane‐2,5‐diol‐ and β‐ionone‐bound CYP101C1 have been solved; both have open conformations and the hexanediol‐bound form has a clear access channel from the heme to the bulk solvent. The entrance of this channel is blocked when β‐ionone binds to the enzyme. The heme moiety of CYP101C1 is in a significantly different environment compared to the other structurally characterised CYP101 enzymes. The likely ferredoxin binding site on the proximal face of CYP101C1 has a different topology but a similar overall positive charge compared to CYP101D1 and CYP101D2, all of which accept electrons from the ArR/Arx class I electron transfer system.     

Novel Cs-Free GaN Photocathodes

We report on a novel GaN photocathode structure that eliminates the use of Cs for photocathode activation. Development of such a photocathode structure promises reduced cost and complexity of the device, potentially with stable operation for a longer time. Device simulation studies suggest that deposition of Si delta-doped GaN on p-GaN templates induces sharp downward energy band bending at the surface, assisting in achieving effective negative electron affinity for GaN photocathodes without the use of Cs. A series of experiments has been performed to optimize the quality of the Si delta-doped layer to minimize the emission threshold of the device. This report includes significant observations relating the dependence of device properties such as emission threshold, quantum efficiency, and surface morphology on the Si incorporation in the Si delta-doped layer. An optimum Si incorporation has been observed to provide the minimum emission threshold of 4.1 eV for the discussed Cs-free GaN photocathodes. Photoemission (PE), atomic force microscopy (AFM), and secondary-ion mass spectroscopy (SIMS) have been performed to study the effect of growth conditions on device performance.     

Elastic analysis of a circular flange joint subjected to axial force

In this paper the general use of a thin circular flange joint is analysed and an exact elastic solution is derived. Formulae which enable the maximum stresses in the joint to be calculated easily are presented. Results obtained using the formulae are compared with those obtained from finite element analyses and with results obtained using other common methods in regular use. The formulae presented are shown to be reliable, accurate and convenient for use in the design of various circular flange joints.     

RQD-D7型交流电动机磁控软起动装置

本文重点介绍了天津市先导倍尔电气有限公司生产的RQD-D7型交流电动机磁控软起动装置的原理、优势及应用。     

The driest continent and the greediest water company: newspaper reporting of drought in Sydney and London

Analysis of press reports of the onset of drought in Sydney in 2002 and London in 2006 shows different understandings of the relationship between infrastructure provision, individual behaviour and the environment. Drought is both a natural and cultural phenomenon requiring urban water managers to consider social as well as technical considerations in preparing for future droughts.     

Effect of chemical treatments on ochratoxigenic fungi and common mycobiota of grapes (Vitis vinifera)

The effect of the application of two fungicides (cyprodinil alone and a mixture of cyprodinil and fludioxonil) on the mycoflora of grapes, especially ochratoxigenic fungi, was studied. Different doses and application times were analyzed. Grape mycobiota was isolated and identified, and the classification of black aspergilli was carried out. We found that 81.7% of the isolates belonged to Aspergillus niger aggregate and 18.3% to Aspergillus carbonarius. The ability to produce ochratoxin A (OTA) was studied on Czapek yeast extract agar (CYA) medium in 238 isolates. Most A. carbonarius (97.2%) produced detectable amounts of OTA, while only 2.9% of the A. niger aggregate were OTA producers. Most of the isolates (58%) produced less than 2.5 microg OTA per g of CYA. That, together with the highest levels of black aspergilli detected near harvest, proved the reported theory that they are primarily responsible for OTA in grapes. The fungicides studied had a significant effect on black aspergilli in three of the four vineyards sampled, as the natural increase of black aspergilli when approaching harvest was in general lower in all the fields treated with fungicides as compared to the control treatment. A mixture of cyprodinil (37.5%) and fludioxonil (25%) applied at veraison and 21 days before harvest was the most effective treatment to prevent black aspergilli in grapes, together with a single application of this mixture at veraison followed by an application of cyprodinil (50%) 21 days before harvest. No OTA was detected in musts (n=112) produced from either the control treatment or the treated grapes.     

Germination alters the chemical composition and protein quality of lupin seeds

The chemical composition and protein quality of the kernels from Lupinus angustifolius seeds were compared with that for sprouts after 6 days germination. Germination resulted in an apparent increase in protein content from 395 g kg^?1 to 435 g kg^?1 DM. Fat and carbohydrate contents decreased. The oligosaccharide content of the sprouted lupin fell to a negligible level, while the phytate and alkaloid concentrations fell from 4.7 g kg^?1 to 1.6 g kg^?1 and from 0.72 g kg^?1 to 0.16 g kg^?1, respectively. The quality of lupin kernel protein was poor with a protein efficiency ratio (PER) of 1.45±0.15. Supplementation of kernel with DL-methionine (2.0 g kg^?1) increased the protein quality (PER = 2.87±0.17) to that of casein (PER = 2.86±0.18). Germination reduced protein quality (PER = 0.44±0.16), and did not improve apparent protein digestibility (APD kernel = 80.4%; APD sprout = 77.5%). Supplementation of sprout protein with DL-methionine (2.0 g kg^?1) increased the protein quality (PER = 2.57±0.20). The total sulphur-containing amino acid concentration of lupin kernel protein, 1.9 g per 16 g N was low, and decreased further to 1.3 g per 16 g N in the sprout, a drop of 32%. The results showed that germination of lupin seeds reduced the concentration of the anti-nutritive factors; however, it also reduced protein quality.     

Explicit Ziv–Zakai bound for analysis of DOA estimation performance of sparse linear arrays

Sparse linear arrays (SLAs) provide similar direction-of-arrival estimation performance to filled linear arrays in terms of angular accuracy and resolution with reduced size, weight, power consumption, and cost. However, they are subject to significant ambiguities due to high sidelobes in the array beampattern, which give rise to large estimation errors. In this paper, we develop an explicit closed-form expression for the Ziv–Zakai bound on the mean square estimation error in order to quantify the degradation in estimation performance due to the sidelobe ambiguities. The bound consists of three terms which correspond to the three types of estimation errors: small mainlobe errors, errors due to sidelobe ambiguities, and random errors. The bound is used to analyze the performance of different SLA configurations. Maximum likelihood estimation simulations confirm the contribution of the different types of estimation errors predicted by the bound. The analysis shows that much of the performance degradation due to ambiguities are from random errors that cannot be controlled by array design, while additional degradation due to sidelobe errors depends strongly on the array configuration. Isolating the contributions of the three types of errors provides greater understanding of the behavior of sparse arrays, allowing for more effective system design and analysis.