Determination of lethality rate constants and D-values for heat-resistant Bacillus spores ATCC 29669 exposed to dry heat from 125°C to 200°C

Exposing flight hardware to dry heat is a NASA-approved sterilization method for reducing microbial bioburden on spacecraft. The existing NASA specification only allows heating the flight hardware between 104°C and 125°C to reduce the number of viable microbes and bacterial spores. Also, the NASA specifications only allow a four log reduction by dry heat microbial reduction because very heat-resistant spores are presumed to exist in a diverse population (0.1%). The goal of this research was to obtain data at higher temperatures than 125°C for one of the most heat-resistant microorganisms discovered in a spacecraft assembly area. These data support expanding the NASA specifications to temperatures higher than 125°C and relaxing the four log reduction specification. Small stainless steel vessels with spores of the Bacillus strain ATCC 29669 were exposed to constant temperatures between 125°C and 200°C under both dry and ambient room humidity for set time durations. After exposures, the thermal spore exposure vessels were cooled and the remaining spores recovered and plated out. Survivor ratios, lethality rate constants, and D-values were determined at each temperature. The D-values for the spores exposed under dry humidity conditions were always found to be shorter than those under ambient humidity. The temperature dependence of the lethality rate constants was obtained by assuming that they obeyed Arrhenius behavior. The results are compared to those of B. atrophaeus ATCC 9372. In all cases, the D-values of ATCC 29669 are between 20 and 50 times longer than those of B. atrophaeus ATCC 9372.     

30CrMnSiNi2A钢表面Cr和Si扩散涂层的抗蚀性

用原位化学气相沉积方法同时沉积铬和硅于３０ＣｒＭｎＳｉＮｉ２Ａ钢上的研究已获成功。试验表明，理想涂层的试样在自来水、０．５％ＮａＣｌ水溶液和０．５ＭＨ２ＳＯ４溶液中都显示了优良的抗蚀性。得到的涂层厚１６０～２００μｍ，表面成分达到２６％～３４％Ｃｒ、约４％的Ｓｉ（ｗｔ％）。该涂层是用９０Ｃｒ－１０Ｓｉ（ｗｔ％）、中间合金、活化剂（９５．５ＮａＦ＋４．５ＮａＣｌ）（ｗｔ％）和填充料（ＳｉＯ２）在一定温度下保持若干小时得到的。     

Mineralization of wastes of human vital activity and plants to be used in a Life Support System

Available methods for mineralizing wastes of human activity and inedible biomass of plants used in this country and abroad are divided into two types: dry mineralization at high temperatures up to 1270 K with subsequent partial dissolution of the ash and the other--wet oxidation by acids. In this case mineralization is performed at a temperature of 470-460 K and a pressure of 220-270 atmospheres in pure oxygen with the output of mineral solution and dissoluble sediments in the form of scale. The drawback of the first method is the formation of dioxins, CO, SO2, NO2 and other toxic compounds. The latter method is too sophisticated and is presently confined to bench testing. The here proposed method to mineralize the wastes is in mid-position between the thermal and physical chemical methods. At a temperature of 80-90 degrees C the mixture was exposed to a controlled electromagnetic field at normal atmospheric pressure. The method merits simplicity, reliability, produces no dissoluble sediment or emissions noxious for human and plants. The basic difference from the above said methods is to employ as an oxidizer atomic oxygen, its active forms including OH-radicals with hydrogen peroxide as the source. Hydrogen peroxide can be produced with electric power from water inside the Life Support System (LSS).     

圆形湍流射流中的Taylor假设

在一湍流射流自模区的中心线上，沿流向的温度空间相关和差分量的统计关系由两种方法获得。一是用两根平行并在流向分离的冷丝直接测量；另一方法是通过计算关于时间的相关和分（根据来自下游位置的冷线信号），以及Ｔａｙｌｏｒ假设法获得关于空间的以应量。本文对有关的时，空量，如相关系数，均方根值，偏斜和平坦因子以及谱密度函数，作了对比和讨论。可以认为，Ｔａｙｌｏｒ假庙所测量的流动中是相当合理有和有用的。     

Biosignatures from Earth-like planets around M dwarfs

Coupled one-dimensional photochemical-climate calculations have been performed for hypothetical Earth-like planets around M dwarfs. Visible/near-infrared and thermal-infrared synthetic spectra of these planets were generated to determine which biosignature gases might be observed by a future, space-based telescope. Our star sample included two observed active M dwarfs-AD Leo and GJ 643-and three quiescent model stars. The spectral distribution of these stars in the ultraviolet generates a different photochemistry on these planets. As a result, the biogenic gases CH4, N2O, and CH3Cl have substantially longer lifetimes and higher mixing ratios than on Earth, making them potentially observable by space-based telescopes. On the active M-star planets, an ozone layer similar to Earth's was developed that resulted in a spectroscopic signature comparable to the terrestrial one. The simultaneous detection of O2 (or O3) and a reduced gas in a planet's atmosphere has been suggested as strong evidence for life. Planets circling M stars may be good locations to search for such evidence.     

Microgravity research results and experiences from the NASA/MIR space station program

The Microgravity Research Program (MRP) participated aggressively in Phase 1 of the International Space Station Program using the Russian Mir Space Station. The Mir Station offered an otherwise unavailable opportunity to explore the advantages and challenges of long duration microgravity space research. Payloads with both National Aeronautics and Space Agency (NASA) and commercial backing were included as well as cooperative research with the Canadian Space Agency (CSA). From this experience, much was learned about long-duration on-orbit science utilization and developing new working relationships with our Russian partner to promote efficient planning, operations, and integration to solve complexities associated with a multiple partner program.

This paper focuses on the microgravity research conducted onboard the Mir space station. It includes the Program preparation and planning necessary to support this type of cross increment research experience; the payloads which were flown; and summaries of significant microgravity science findings.     

基于统计特征的稳健的飞机识别

给出了一种用于稳健的高距离分辨率（HRR）雷达飞机识别（ID）的基于统计特征（StaF)的分类器，HRR波形峰特征在飞行中选择，没有对特征的数目与位置作出先验假设。所抽取的特征取决于所观测的波形（使特征的数目、位置与幅度为随机变量）的信息内涵，这项研究的主要目的是通过保持对已知目标的高识别率同时又使未知目标错误最小来提高分类的稳健性。文中给出了识别结果，表明这种统计特征（StaF)分类器可以显著地降低与未知目标相关的误差，同时保持很高的正确分类概率。     

The Urey instrument: an advanced in situ organic and oxidant detector for Mars exploration

The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.     

光纤读出的微光机电振动传感器

针对采用半导体工艺加工的微机械结构对振动进行测量的问题,提出了基微光机电系统(MOEMS)结构并采用光纤读出的振动传感器的设计方案,分析了该传感器的基本测量原理并推导了数学模型.该传感器采用单光纤的读出方式,利用固定于探测器敏感头前端的微结构感受待测物体的振动,通过测量由微结构振动引起的反射光强度的变化,实现对振动的测量.单光纤结构的使用和微结构参数的合理设计,使得该系统与传统的光纤读出系统相比,具有灵敏度高、尺寸小、易于同光纤匹配的特点.应用该系统对压电陶瓷的振动情况进行测量,可探测到0.18nm的位移.      

一种面向对象的机场跑道变化检测方法

利用遥感影像变化检测技术获取机场跑道变化信息,可以为机场跑道打击效果评估等多种军事应用提供决策支撑。为了快速、准确的检测出机场跑道的变化区域,并定量、定性的获得变化属性,文章以"资源三号"卫星影像为例,提出了一种新的面向对象的机场跑道变化检测方法。首先,将经过配准处理的前后时相遥感影像进行多尺度分割,分割尺度利用尺度参数估计(Estimation of Scale Parameters,ESP)算法确定;之后,利用影像分割结果对不同时相的对象进行切割,形成前后时相上位置、大小一致的对象单元,再利用不同时相对象间的变化向量大小确定变化区域;最后,利用特征空间优化之后的特征集合对已确定的变化区域对象进行监督分类,获得机场跑道内部各对象的变化属性。结果表明:在变化区域的检测上,该方法避免了单张影像的分类过程,可有效提高检测效率;在变化类别的检测上,该方法在检测出的变化区域基础上进行分类,可大幅提高变化类别的检测精度,并且能够获得更为丰富的变化属性和满足快速准确检测机场跑道相关变化的信息。