Vickers indentation hardness of Hg1−xCdxTe

The Vickers indentation hardness of Hg_1−xCd_xTe has been measured as a function of composition x using monocrystalline samples of Bridgman and THM crystals and polycrystalline starting material at room temperature. The microhardness varied between 220 MPa (x=0) and 440 MPa (x=1), showing a maximum of 850 MPa at x ∼ 0.75, and was different between monocrystalline and polycrystalline samples. The “hardening rate” dH/dx is strongly dependent on the composition range and is discussed in context with solid solution hardening due to elastic interactions of solute atoms with gliding dislocations and ordering effects.     

Deformation Induced Micro-Twins in CdTe?

Room- and high-temperature micro-indentation experiments have been performed to answer the question if, concerning a material with very low stacking-fault energy like CdTe, deformation induced twinning occurs in these substances during or shortly after growth. Micro-twins appear in consequence of room-temperature deformation only, whereas microindentation at 565°C does not produce any twins, but leads to widely expanded dislocation glide-figures, due to dislocation climbing and/or cross-gliding.     

Mammalian-like Purple Acid Phosphatases in Plants

Introduction Purpleacidphosphatases(PAPs)compriseofa familyofbinuclearmetal containinghydrolases,some membersofwhichhavebeenisolatedandcharacterized fromanimal,plantandfungalsources[1].PAPsnoton lycatalyzethehydrolysesofawiderangeofphosphate estersandanhy…     

Illumination Sensing in LED Lighting Systems Based on Frequency-Division Multiplexing

Recently, light emitting diode (LED) based illumination systems have attracted considerable research interest. Such systems normally consist of a large number of LEDs. In order to facilitate the control of such high-complexity system, a novel signal processing application, namely illumination sensing, is thus studied. In this paper, the system concept and research challenges of illumination sensing are presented. Thereafter, we investigate a frequency-division multiplexing (FDM) scheme to distinguish the signals from different LEDs, such that we are able to estimate the illuminances of all the LEDs simultaneously. Moreover, a filter bank sensor structure is proposed to study the key properties of the FDM scheme. Conditions on the design of the filter response are imposed for the ideal case without the existence of any frequency inaccuracy, as well as for the case with frequency inaccuracies. The maximum number of LEDs that can be supported for each case is also derived. In particular, it is shown that, among all the other considered functions, the use of the triangular function is able to give a better tradeoff between the number of LEDs that can be supported and the allowable clock inaccuracies within a practical range. Moreover, through numerical investigations, we show that many tens of LEDs can be supported for the considered system parameters. Remark on the low-cost implementations of the proposed sensor structure is also provided.     

CaII Binding Regulates and Dominates the Reactivity of a Transition‐Metal‐Ion‐Dependent Diesterase from Mycobacterium tuberculosis

The diesterase Rv0805 from Mycobacterium tuberculosis is a dinuclear metallohydrolase that plays an important role in signal transduction by controlling the intracellular levels of cyclic nucleotides. As Rv0805 is essential for mycobacterial growth it is a promising new target for the development of chemotherapeutics to treat tuberculosis. The in vivo metal‐ion composition of Rv0805 is subject to debate. Here, we demonstrate that the active site accommodates two divalent transition metal ions with binding affinities ranging from approximately 50 nm for Mn^II to about 600 nm for Zn^II. In contrast, the enzyme GpdQ from Enterobacter aerogenes, despite having a coordination sphere identical to that of Rv0805, binds only one metal ion in the absence of substrate, thus demonstrating the significance of the outer sphere to modulate metal‐ion binding and enzymatic reactivity. Ca^II also binds tightly to Rv0805 (K_d≈40 nm ), but kinetic, calorimetric, and spectroscopic data indicate that two Ca^II ions bind at a site different from the dinuclear transition‐metal‐ion binding site. Ca^II acts as an activator of the enzymatic activity but is able to promote the hydrolysis of substrates even in the absence of transition‐metal ions, thus providing an effective strategy for the regulation of the enzymatic activity.     

Direct synthesis of isothiocyanates from isonitriles by molybdenum-catalyzed sulfur transfer with elemental sulfur

The direct molybdenum-catalyzed sulfuration of a variety of isonitriles with elemental sulfur or propene sulfide as sulfur donors affords the corresponding isothiocyanates in good yields and under mild reaction conditions. A catalytic cycle is suggested, in which the molybdenum oxo disulfur complex operates as the active sulfur-transferring species. A novel adduct between the isonitrile and the molybdenum complex has been characterized by X-ray analysis and its association constant determined by UV-vis spectroscopy, but this adduct appears not to be involved in the sulfur-transfer process.