配给能源采集供电:无线传感器节点的功率约束

让周遭的系统能够自动感测环境变化并做出反应，势必将对于人类的生活造成重大改变。无线传感器网络是多个分布式传感器实作（节点）组成的系统，能够共同透过相互无线通信的方式响应实体变化。本文将重点介绍节点的最新进展，并推广对于系统层级设计方法的需求。     

An Improved Direct Oxidation of Alkyl Halides to Aldehydes

The oxidation of alkyl chlorides and bromides with dimethyl sulfoxide has been performed in the presence of sodium iodide. This method allows a convenient one-step procedure for the preparation of aldehydes from alkyl chlorides and bromides.     

On the Supposed Isoindole Synthesis from o-Tolunitrile

A recent communication¹ in this journal reported the reaction of o-tolunitrile with sodium in tetrahydrofuran to yield a compound, m.p. 123.5–124°, to which was assigned the isoindole structure 1. A plausible mechanism can be written for the formation of 1 involving reductive dimerization of the cyano groups of two molecules of the nitrile, subsequent 1,5-hydrogen shift from a methyl group, disrotatory electrocyclic isoindole ring closure, and finally air oxidation and tautomerization to 1. Nevertheless, the evidence presented did not require an isoindole structure. Moreover, it would be unusual for a primary enamine to survive.     

Magnetically Aligned Supramolecular Hydrogels

The magnetic‐field‐induced alignment of the fibrillar structures present in an aqueous solution of a dipeptide gelator, and the subsequent retention of this alignment upon transformation to a hydrogel upon the addition of CaCl₂ or upon a reduction in solution pH is reported. Utilising the switchable nature of the magnetic field coupled with the slow diffusion of CaCl₂, it is possible to precisely control the extent of anisotropy across a hydrogel, something that is generally very difficult to do using alternative methods. The approach is readily extended to other compounds that form viscous solutions at high pH. It is expected that this work will greatly expand the utility of such low‐molecular‐weight gelators (LMWG) in areas where alignment is key.     

Environmentally benign nanomixing by sonication in high-pressure carbon dioxide

Due to the increased use of nanocomposites, mixing at nanoscale has become important. Current mixing techniques can be classified into: (a) dry mixing (mechanical mixing), (b) wet mixing, and (c) simultaneous production of mixed nanoparticles (when possible). Dry mixing is in general not effective in achieving desired mixing at nanoscale, whereas wet mixing suffers from different disadvantages like nanomaterial of interest should be insoluble, has to wet the liquid, and involves additional steps of filtration and drying. This paper examines the use of pressurized carbon dioxide having high density and low viscosity to replace the liquids (e.g., n-hexane, toluene). Ultrasound is applied to the suspension of nanopowders in gaseous and supercritical carbon dioxide where high impact collisions during sonication help mixing and the final mixture is obtained by simple depressurization. The method is tested for binary mixture of alumina/silica, silica/titania, MWNT (multiwalled carbon nanotubes)/silica, and MWNT/titania. The effects of sonication intensity and pressure on the degree of mixing are studied. Comparative study is also done with liquid n-hexane as a mixing media. Quantitative characterization (e.g., mean composition standard deviation, intensity of segregation) of mixing of alumina/silica and silica/titania is done with energy-dispersive X-ray spectroscopy, and that of MWNT/silica and MWNT/titania is done using field-emission scanning electron microscopy and day-light illumination spectrophotometry. Results show that mixing in carbon dioxide at higher ultrasound amplitudes is as good as in liquid n-hexane, and the final mixed product does not contain any residual media as in the case of liquid n-hexane.     

From workplace air measurement results toward estimates of exposure? Development of a strategy to assess exposure to manufactured nano-objects

In the past few years, an increasing number of studies on workplace air measurements on manufactured nano-materials and -objects have been published. Most of the studies had a more explorative character, so a direct interpretation to workers” exposure for a given exposure situation, activity, or process is not a straight-forward process. In general, the studies use a quite similar package of devices for near real-time monitoring of particle number- and mass concentration in size ranges <100 nm up to 10 μm, and the collection of samples for off-line characterization of air samples. Various approaches for addressing background concentrations and its use to indicate the potential for exposure to nano-objects could be observed. Within the EU-sponsored NANOSH project, a harmonized approach for measurement strategy, data analysis and reporting was developed. In addition to time/activity–concentration profiles as reported by most studies, this approach enables a first step to estimate the potential for exposure to manufactured nano-objects, more quantitatively. The NANOSH data will be collated into a base, which may form the starting point for a harmonized database facilitating overall analysis in near future, to derive estimates for exposure for several exposure situations.     

Generation of a Recombinant Full-Length Human Antibody Binding to Botulinum Neurotoxin A

In order to develop a recombinant full-length human anti-botulinum neurotoxin A (BoNT/A) antibody, human peripheral blood mononuclear cells (PBMC) were collected from three healthy volunteers and induced for BoNT/A-specific immune response by in vitro immunization. The genes encoding human Fd fragment, consisting of antibody heavy chain variable region and constant region 1 with the genes encoding antibody light chain, were cloned from the immunized PBMC. Afterwards, one combinatory human antigen-binding fragment (Fab) library was constructed using a lambda phage vector system. The size of the constructed library was approximately 10⁵ Escherichia coli transformants. After screening the library by BoNT/A antigen using a plaque lifting with immunostaining approach, 55 clones were identified as positive. The Fab gene of the most reactive clone exhibiting particularly strong BoNT/A binding signal was further subcloned into a full-length human IgG1 antibody gene template in an adenoviral expression vector, in which the heavy and light chains were linked by a foot-and-mouth-disease virus-derived 2A self-cleavage peptide under a single promoter. After the full-length human IgG1 was expressed in mammalian cells and purified with protein L column, sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the heavy and light chains of the antibody were cleaved completely. The affinity expressed as the dissociation constant (K _d) for the recombinant human antibody to bind to BoNT/A was determined by indirect enzyme-linked immunosorbent assay and results confirmed that the recombinant full-length human antibody retained BoNT/A-binding specificity with K _d value of 10⁻⁷ M.     

Ion-trap quantum information processing:experimental status

Atomic ions trapped in ultra-high vacuum form an especially well-understood and useful physical system for quantum information processing. They provide excellent shielding of quantum information from environmental noise, while strong, well-controlled laser interactions readily provide quantum logic gates. A number of basic quantum information protocols have been demonstrated with trapped ions. Much current work aims at the construction of large-scale ion-trap quantum computers using complex microfabricated trap arrays. Several groups are also actively pursuing quantum interfacing of trapped ions with photons.      

Focus on H/D exchange of proteins in solution

Editorial

Focus on H/D exchange of proteins in solution