Multiple-proxy lacustrine record of moisture transport over western North America from 24,000 to 12,000 YBP, Lake Estancia, New Mexico [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Pluvial Lake Estancia in central New Mexico experienced large and rapid fluctuations in surface area and elevation during the build-up to and termination of the last glacial maximum (LGM). Due to continuous groundwater discharge, a minimum pool covering about 400 square kilometers was maintained in the central basin until about 12,000 years ago, ensuring a continuous depositional sequence even during low stands of the lake. ... The sensitive response to fluctuations in climate by several independent proxies at Estancia show that transport of Pacific moisture over western North America changed dramatically during the last Ice Age, perhaps comparable to the large and rapid changes in climate documented from high-latitude ice and North Atlantic marine sediments for the LCM and its transitions.

A rock-magnetic and geomagnetic secular variation record from late-Pleistocene Lake Estancia, New Mexico [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Exposed sediments of Late Pleistocene Lake Estancia contain a high resolution record of regional climate variability for the period about 12,000 to 32,000 years. A detailed rock-magnetic study is being performed on this well-dated, well-preserved sedimentary sequence to determine how the magnetic signature of sediments responded to regional climate change.

Monoculture of marine planktonic diatoms and the effects of different media on their growth and survival

Diatoms are the preferred live food of the protozoea stages of prawns. Due to seasonal variations, it is difficult to obtain continuous supply of diatoms and other algae throughout the year. Therefore mass culture of diatoms is necessary. At attempt was made to culture planktonic diatoms and to study the effect of Allen and Nelson media, Simon media, Vitamin B12 and treated sewage water media on their growth and survival. Navicula sp showed better growth in Allen and Nelson media, Coscinodiscus and Chaetoceros grew better in Simon media while Navicula sp and Coscinodiscus sp showed better growth in the combination of Allen and Nelson + Vitamin B12.

发菜类囊体膜的组成及其光合特性的研究

发菜（Nostoc flagelliforme Born. et Flah.）的细胞壁由纤维素、半纤维素、糖脂和蛋白质组成。未经破碎的细胞难以进行各种光合特性的研究。由于纯度较高的发菜类囊体膜制备比较困难，对它的光合机理的研究一直是停留在整体水平上进行。我们采用French Press低温下高压破碎细胞，建立了一种快速简便的制备方法。在提取液中加入一定浓度的Ca2+ （Ca2+既有助于维持类囊体膜的放氧活性又可以使类囊体膜在较低的离心速度下使类囊体膜得到凝集沉淀），从而在较短时间内、在高速离心的情况下得到了纯度较高并具有较高放氧活性的发菜类囊体膜。在此基础上，我们采用改进的Allen（1991）的温和绿胶系统，首次对陆生蓝藻发菜类囊体膜色素蛋白复合体进行了分离，共分离出了11条绿色的色素蛋白复合物条带和两条浅黄色的条带。7条绿色的色素蛋白复合物条带属于PSI组分，4条绿色的蛋白复合物条带属于PSII组分，其中一条浅黄色条带系未被报道过的新的色素蛋白复合物条带，经其光谱性质的分析初步鉴定为类胡萝卜素蛋白复合物，此复合物的分离有助于解释发菜独特的适应荒漠、半荒漠地带高光辐射的特性。 本文还对干燥状态、复水30分钟后和复水生长24小时后的野生发菜及人工培养的发菜藻丝体膜脂及其脂肪酸组成进行了分析。发菜的膜脂由MGDG、MGDG、SQDG和PG组成，其酯酰基部位连接有16:0、16:1、18:0、18:1、18:2和18:3六种脂肪酸。野生发菜中具有高含量的不饱和脂肪酸，其含量可达总脂的73%，其中16:1和18:3分别达到28.9mol%和34.3mol%，远远高于已报道的其它蓝藻，所以我们推测发菜具有极强的抗逆性和其膜脂不饱和程度密切相关。分析不同处理的发菜的膜脂和脂肪酸组成表明，复水对野生发菜的膜脂及其脂肪酸组成没有显著影响，说明发菜的膜脂和脂肪酸组成在干燥状态下能保持很高的稳定性。从野生发菜分离出的藻丝体在25 ℃条件下培养，其膜脂脂肪酸组成发生了显著变化，主要表现为脂肪酸的不饱和程度的大幅度降低，18:3从34.9mol%降低到8.6mol%，16:1从28.9mol%降低到13.9mol%。上述结果表明了发菜具有极强的通过改变其膜脂的脂肪酸组成而适应生存环境的能力。

Post-processing of vertical-cavity surface-emitting lasers for transverse mode and polarization control

The operation on how high quality single-mode operation can be readily attained on etching circles in multimode devices is discussed. Arrays of such spots can also be envisaged. Control of the polarization state is also achieved by use of deep line etches. The output filaments and beam shapes of the conventional multimode vertical cavity surface emitting lasers (VCSEL) is shown to be engineered in terms of their positions, widths, and polarizations by use of focused ion beam etching (FIBE). Several GaAs quantum well top-emitting devices with cavity diameters of 10 μm and 18 μm were investigated.

Mode control in vertical-cavity surface-emitting lasers by post-processing using focused ion-beaih etching

Single-mode emission is achieved in previously multimode gain-guided vertical-cavity surface-emitting lasers (VCSEL's) by localized modification of the mirror reflectivity using focused ion-beam etching. Reflectivity engineering is also demonstrated to suppress transverse mode emission in an oxide-confined device, reducing the spectral width from 1.2 nm to less than 0.5 nm.

High power laser with integrated lens using focused ion beam etching

In this study, a collimating lens is introduced at the output facet of a tapered waveguide laser to compensate for the divergence of the optical mode. The collimating lens is shown to enhance the laser efficiency while simultaneously reducing the far field divergence.

Operatives for off-shore and deep-sea fishing vessels

The need for operatives for the offshore and deep-sea fishing vessels is currently very great, and the importance of fisheries training has long been recognized by the Department of Fisheries. In 1974 the Sri Lanka Fisheries Training Institute was established with Japanese aid. The author discusses the purpose and functions of the institute, the first batch of trainees from which finished their training in June 1977. Annexes describe the courses offered, diplomas and certificates, admission requirements, and the conditions required for candidates sitting second-hand fishing vessel examination of the Mercantile Marine Department, Bombay District.

Focused ion beam etching of GaN

We have investigated the use of focused ion beam (FIB) etching for the fabrication of GaN-based devices. Although work has shown that conventional reactive ion etching (RIE) is in most cases appropriate for the GaN device fabrication, the direct write facility of FIB etching - a well-established technique for optical mask repair and for IC failure analysis and repair - without the requirement for depositing an etch mask is invaluable. A gallium ion beam of about 20nm diameter was used to sputter GaN material. The etching rate depends linearly on the ion dose per area with a slope of 3.5×10 -4μm3/pC. At a current of 3nA, for example, this corresponds to an etch rate of 1.05μm3/s. Good etching qualities have been achieved with a side wall roughness significantly below 0.1μm. Changes in the roughness of the etched surface plane stay below 8nm.

AN ACTIVATOR OF BLOOD-COAGULATION FACTOR-X FROM THE VENOM OF BUNGARUS-FASCIATUS

A specific activator of blood coagulation factor X was purified from the venom of Bungarus fasciatus by gel filtration and by ion-exchange chromatography on a Mono-Q column (FPLC). It consisted of a single polypeptide chain, with a mel. wt of 70,000 in reducing and non-reducing conditions. The enzyme had an amidolytic activity towards the chromogenic substrates S-2266 and S-2302 but it did not hydrolyse S-2238, S2251 or S-2222, which are specific substrates for thrombin, plasmin and factor Xa, respectively. The enzyme activated factor X in vitro and the effect was Ca2+ dependent with a Hill coefficient of 7.9. As with physiological activators, the venom activator cleaves the heavy chain of factor X, producing the activated factor Xa alpha. The purified factor X activator from B. fasciatus venom did not activate prothrombin, nor did it cleave or clot purified fibrinogen. The amidolytic activity and the factor X activation activity of the factor X activator from B. fasciatus venom were readily inhibited by serine protease inhibitors such as diisopropyl fluorophosphate (DFP), phenylmethanesulfonyl fluoride (PMSF), benzamidine and by soybean trypsin inhibitor but not by EDTA. These observations suggest that the factor X activator from B. fasciatus venom is a serine protease. It therefore differs from those of activators obtained from Vipera russelli and Bothrops atrox venoms, which are metalloproteinases.

Characterization of three fibrinogenolytic enzymes from Chinese green tree viper (Trimeresurus stejnegeri) venom

Rong Gao, Yun Zhang, Qing-Xiong Meng, Wen-Hui Lee, Dong-Sheng Li, Yu-liang Xiong and Wan-Yu Wang. Characterization of three fibrinogenolytic enzymes from Chinese green tree viper (Trimeresurus stejneger ) venom. Toxicon 36, 457-467, 1998.-From the venom of Chinese green tree viper (Trimeresurus stejnegeri), three distinct fibrinogenolytic enzymes: stejnefibrase-l, stejnefibrase-2 and stejnefibrase-3, were purified by gel filtration, ion-exchange chromatography and reverse-phase high-performance chromatograghy (HPLC). SDS-PAGE analysis of those three enzymes showed that they consisted of a single polypeptide chain with mel. wt of -50 000, 31 000 and 32 000, respectively. Like TSV-PA (a specific plasminogen activator) and stejnobin (a fibrinogen-clotting enzyme) purified from the same venom, stejnfibrase-1, -2 and -3 were able to hydrolyze several chromogenic substrate. On the other hand, different from TSV-PA. and stejnobin, stejnefibrase-l, -2 and -3 did not activate plasminogen and did not possess fibrinogen-clotting activity. The three purified enzymes directly degraded fibrinogen to small fragments and rendered it unclottable by thrombin. Stejnefibrase-2 degraded preferentially BE-chain while stejnefibrase-l and -3 cleaved concomitantly Ax and B beta-chains of fibrinogen. None of these proteases degraded the gamma-chain of fibrinogen. When correlated with the loss of clottability of fibrinogen, the most active enzyme was stejnefibrase-l. The activities of the three enzymes were inhibited by phenylmethylsulfonyl fluoride (PMSF) and p-nitrophenyl-p-guanidinobenzoate (NPGB), indicating that like TSV-PA and stejnobin, they are venom serine proteases. (C) 1998 Elsevier Science Ltd. All rights reserved.