New Beta-lactamases in Candidate Phyla Radiation: Owning Pleiotropic Enzymes Is a Smart Paradigm for Microorganisms with a Reduced Genome

The increased exploitation of microbial sequencing methods has shed light on the high diversity of new microorganisms named Candidate Phyla Radiation (CPR). CPR are mainly detected via 16S rRNA/metabarcoding analyses or metagenomics and are found to be abundant in all environments and present in different human microbiomes. These microbes, characterized by their symbiotic/epiparasitic lifestyle with bacteria, are directly exposed to competition with other microorganisms sharing the same ecological niche. Recently, a rich repertoire of enzymes with antibiotic resistance activity has been found in CPR genomes by using an in silico adapted screening strategy. This reservoir has shown a high prevalence of putative beta-lactamase-encoding genes. We expressed and purified five putative beta-lactamase sequences having the essential domains and functional motifs from class A and class B beta-lactamase. Their enzymatic activities were tested against various beta-lactam substrates using liquid chromatography-mass spectrometry (LC-MS) and showed some beta-lactamase activity even in the presence of a beta-lactamase inhibitor. In addition, ribonuclease activity was demonstrated against RNA that was not inhibited by sulbactam and EDTA. None of these proteins could degrade single- and double-stranded-DNA. This study is the first to express and test putative CPR beta-lactamase protein sequences in vitro. Our findings highlight that the reduced genomes of CPR members harbor sequences encoding for beta-lactamases known to be multifunction hydrolase enzymes.     

Symbol synchronization using signal samples and interpolation

A method for symbol synchronization using two unsynchronized signal samples per symbol is presented. Signal values between the sample points are calculated by interpolation and then processed digitally to find a suitable strobe point. The interpolated value at the strobe point is used for data detection or input to an equalizer. Simulations show that low variance timing estimates can be made for pulses with raised-cosine spectra degraded by quadratic delay distortion     

嵌入式POL DC/DC转换器设计

大多数嵌入式系统都是通过48V背板供电的。这个电压通常要降为更低的12V或5V中间电压,以向系统内的电路板供电。然而,在这些电路板上,大多数电路都要求供电电压范围在0.8V～3.3V,电流范围为几十mA至几十A。因此,需要负载点(POL)DC/DC转换器对12V或5V降压,以获得所需的电压和电流值。     

Technologies and the development of the Automated Metadata Indexing and Analysis (AMIA) system

The Automated Metadata Indexing and Analysis (AMIA) project aims to provide an effective digital asset management (DAM) tool for large digital asset databases. We began with text-based indexing since it is still the most reliable approach as compared with other content-based media features. AMIA not only searches for the text of the file name, but also utilizes embedded information such as the metadata in Maya files. The AMIA system builds a linked map between all dependency files. We present an approach of preserving previously established metadata created by the old DAM tools, such as AlienBrain, and integrating them into the new system. Findings indicate that AMIA has significantly improved search performance comparing to previous DAM tools. Finally, the ongoing and future work in the AMIA project is described.     

The manufacture and performance of diodes made in dielectricallyisolated silicon substrates containing buried metallic layers

Results are reported on the performance of diffused p⁺n diode structures manufactured on a novel silicon-on-metal-on-insulator (SMI) substrate. This substrate consists of a thin single crystal silicon layer on top of a tungsten disilicide covered oxidized silicon wafer. The diodes show excellent characteristics with an exponential current-voltage (I-V) relationship over nine orders of magnitude and an ideality factor of 1.005, under forward bias conditions. The reverse leakage current is low with a minority carrier lifetime of typically 500 μs. The diodes show no evidence of stress induced defects or degraded performance due to W migration during processing. The SMI substrate is therefore shown to be compatible with standard manufacturing processes     

Fabrication and characterisation of high resistivity SOI substrates for monolithic high energy physics detectors

Silicon on insulator (SOI) substrates offer a promising platform for monolithic high energy physics detectors with integrated read-out electronics and pixel diodes. This paper describes the fabrication and characterisation of specially-configured SOI substrates using improved bonded wafer ion split and grind/polish technologies. The crucial interface between the high resistivity handle silicon and the SOI buried oxide has been characterised using both pixel diodes and circular geometry MOS transistors. Pixel diode breakdown voltages were typically greater than 100 V and average leakage current densities at 70 V were only 55 nA/cm². MOS transistors subjected to 24 GeV proton irradiation showed an increased SOI buried oxide trapped charge of only 3.45 × 10¹¹ cm^?2 for a dose of 2.7 Mrad.     

电缆与连接器（四）

（上接2008年第3期100页）2．6．8为何接地环路对EMC设计没有影响接地环路有时也称作噪声回路,因为在EMC设计有缺陷的音响系统中接地环路会引起嗡嗡的噪声。通常的做法是采用单点接地和电缆屏蔽层的单端搭接,从而避免形成接地环路,但是接地环路问题其实是由不恰当的产品设计所引起的。     

外部干扰的抑制（二）

6．1．4控制屏蔽机箱的放电 屏蔽是一种抑制ESD的有效方式,可以对ESD进行适当的控制,使得ESD不会影响产品内部电路的正常工作。第4部分内容对屏蔽技术进行了讨论,我们所要做的就是让机箱在非常高的频率具有理想的屏蔽效能。     

Nitrous oxide emissions from two sites in Southern England during winter 1981/1982

Nitrous oxide fluxes from soil surfaces were measured during winter 1981/82 on two fallow sites, a loamy sand and a clay loam, that had been watered to field capacity and fertilised at the rate of 200 kg N ha^?1 on the 5 October 1981. Highest fluxes were obtained in the sampling period immediately after fertiliser application. They were in the range 3.5–20 g N₂O? N ha^?1 day^?1 on the loamy sand, and declined rapidly from a peak of almost 165 g N₂O? N ha^?1 day^?1 on the day following fertiliser application on the clay loam. The temperature during this period was in the range 6.5 to 14°C. As soil temperature declined during the sampling periods in December (?2 to 3°C) and February (4.5 to 6.5°C) and nitrate was leached in the subsoil, N₂O evolution became very low (<1 g N₂O? N ha^?1 day^?1). Rainfall over the whole sampling period from early October to mid-February was 282 mm. On both sites there was a very high degree of variability within the sites at any sampling time.     

便携设备的电源管理技术展望

2005年对以电池驱动的便携设备的电源管理解决方案来说，将是充满机遇的一年。这些设备的制造商不断在寻求各种可能的方式，以把更多的功能合并到一个已经很紧凑的外壳中，这说明他们将不断需要具有高度集成、最小占位面积、最高运行效率的集成电路解决方案，以延长电池的使用时间。