Assessment of the efficacy of Artemia sp (Crustacea) cysts chorion as barrier to chlorpyrifos (organophosphorus pesticide) exposure. Effect on hatching and survival

In order to reveal the efficacy of the Artemia cysts chorion as barrier to the organophosphorus pesticide chlorpyrifos, whole and decapsulated cysts have been exposed to 10 mg L(-1) chlorpyrifos in sea water during hydration and hatching phase, separately. The concentration of chlorpyrifos in capsulated and decapsulated cysts after exposure has been determined in order to elucidate the efficacy of chorion as protection to the embryo. The results obtained demonstrate the ability of the cysts chorion to obstruct the pass of chlorpyrifos molecules through this protection structure. Thus, the concentration of chlorpyrifos in exposed decapsulated cysts is higher than in exposed whole cysts. Moreover, after removing the chorion of exposed cysts, the concentration of chlorpyrifos in the embryo was lower than that of cysts exposed, what would demonstrate the retention of chlorpyrifos molecules by the shell. Hatching was not severely affected by exposure to the insecticide whereas survival at 44 h of the nauplii exposed to chlorpyrifos was significantly different from the controls. Survival of nauplii hatched from exposed decapsulated cysts was higher than that from those hatched from exposed whole cysts, probably because of the lower vitality of the latter, due to depletion of energy reserves during hatching.     

The pulse thermal processing of nanocrystalline silicon thin-films

Pulse thermal processing (PTP) has the capability of processing thin-films and nanoparticles over broad areas utilizing high-density infrared plasma arc lamp technology. Heating rates reaching 600,000°C/s, which is orders of magnitude larger than current state-of-the-art rapid thermal annealing systems, are possible that allow controlled diffusion on the nanoscale. The ability to control heating at these levels permits processing thin-films and nanoparticles on temperature-sensitive substrates such as polymers. The PTP technique has been used to crystallize sputtered amorphous silicon thin-films on sapphire substrates. For more information, contact R.D. Ott, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6083; (865) 574-5172; fax (865) 574-4357; e-mail ottr@ornl.gov.     

Tunable photoactivation of a post-translationally modified signaling protein and its unmodified counterpart in live cells

An ideal technology for direct imaging of post-translationally modified proteins would be one in which the appearance of a fluorescent signal is linked to a modification dependent protein-activation event. Herein, we utilize the protein semisynthesis technique, expressed protein ligation (EPL), to prepare caged analogues of the signaling protein Smad2; the function and fluorescence of the analogues were then photocontrolled in a correlated fashion. We show that this strategy permits titration of the cellular levels of active phosphorylated Smad2 in its biologically relevant, full-length form. We also prepared a nonphosphorylated, caged full-length Smad2 analogue labeled with an orthogonal fluorophore, and simultaneously imaged the phosphorylated and nonphosphorylated forms of the protein in the same cell. This strategy should enable the dissection of the cellular consequences of post-translational modifications (PTMs) by direct comparison of the behavior of the modified and unmodified forms of the protein following uncaging.     

Clinical microscopic analysis of protaper retreatment system efficacy considering root canal thirds using three endodontic sealers

To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty‐five palatal root canals of first molars were filled with gutta‐percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10×), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal‐Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third. Microsc. Res. Tech. 75:1233–1236, 2012. © 2012 Wiley Periodicals, Inc.     

SiGe MOSFET structures on silicon-on-sapphire substrates grown by ultra-high vacuum chemical vapor deposition

SiGe heterostructures on silicon-on-sapphire (SOS) substrates were investigated to determine the advantages of combining these two technologies. Devicequality epitaxial layer structures were grown by ultra-high vacuum chemical vapor deposition (UHV/CVD) on silicon-on-sapphire substrates having a very low density of microtwin defects. Enhancements in device performance comparable to similar SiGe devices on bulk Si substrates were achieved, even though significant interdiffusion of Si and Ge had occurred during device fabrication processes at T>850°C. These results emphasize the need for low temperature fabrication processes to fully exploit SiGe heterostructures for device applications.     

Expression and Functional Studies on the Noncoding RNA,PRINS

PRINS, a noncoding RNA identified earlier by our research group, contributes to psoriasis susceptibility and cellular stress response. We have now studied the cellular and histological distribution of PRINS by using in situ hybridization and demonstrated variable expressions in different human tissues and a consistent staining pattern in epidermal keratinocytes and in vitro cultured keratinocytes. To identify the cellular function(s) of PRINS, we searched for a direct interacting partner(s) of this stress-induced molecule. In HaCaT and NHEK cell lysates, the protein proved to be nucleophosmin (NPM) protein as a potential physical interactor with PRINS. Immunohistochemical experiments revealed an elevated expression of NPM in the dividing cells of the basal layers of psoriatic involved skin samples as compared with healthy and psoriatic uninvolved samples. Others have previously shown that NPM is a ubiquitously expressed nucleolar phosphoprotein which shuttles to the nucleoplasm after UV-B irradiation in fibroblasts and cancer cells. We detected a similar translocation of NPM in UV-B-irradiated cultured keratinocytes. The gene-specific silencing of PRINS resulted in the retention of NPM in the nucleolus of UV-B-irradiated keratinocytes; suggesting that PRINS may play a role in the NPM-mediated cellular stress response in the skin.     

Mixed recycling with emulsion and cement of asphalt pavements. Design procedure and improvements achieved

Cold in place recycling, as an alternative to milling and standard replacement, shows a series of technical, economic and environmental advantages, which have done its use to grow in Spain, especially from 1990 onwards. Nevertheless, these actions have revealed certain aspects and limitations that prevent cold recycling from being considered a fully consolidated technique nowadays. The use of vaguely defined criteria for the design of the recycled mix, the lack of criteria for construction control as well as of specifications about the end product, and the ignorance of the evolution of the material performance with time have given cold recycling some technical insecurity. In this article, the problems arising from the standard methodology used for the design of cold recycled mixes have been analysed firstly, as well as the effect that certain variables, compaction and curing especially, have on their properties. Secondly, the effect that the use of both emulsion and cement during recycling has on the mix properties has been studied, comparing the results with those obtained by means of the standard procedures where only emulsion or cement are used. Finally, a new methodology for the design and control of the recycled mix has been suggested.     

Physical and chemical modification of zinc carboxylate‐containing lubricants by molecular structure changes

Twenty‐two samples of zinc carboxylates were prepared from saturated, non‐cyclic carboxylic acids with systematically altered hydrocarbon chain structures under well‐defined conditions. Essential temperature‐ and solvent‐induced changes concerning the coordination of the carboxylate group are shown using selected prepared samples, and general rules for systems containing zinc carboxylates in nonpolar media are presented. It is shown that there are three possible structural forms for zinc carboxylates: polymeric sheet, polymeric chain, and closed tetranuclear oxo complex molecules. These forms are closely related through their physical and chemical transitions. The results show that the spatial structure of the hydrocarbon chain is a crucial factor, besides physical and chemical conditions, limiting the possible forms of zinc carboxylates present in the system. The principles presented enable us to predict and design the behaviour of a system containing zinc carboxylate additives.     

Low‐temperature formation of local Al contacts to a‐Si:H‐passivated Si wafers

We have passivated boron‐doped, low‐resistivity crystalline silicon wafers on both sides by a layer of intrinsic, amorphous silicon (a‐Si:H). Local aluminum contacts were subsequently evaporated through a shadow mask. Annealing at 210°C in air dissolved the a‐Si:H underneath the Al layer and reduces the contact resistivity from above 1 Ω cm² to 14·9 m Ω cm². The average surface recombination velocity is 124 cm/s for the annealed samples with 6% metallization fraction. In contrast to the metallized regions, no structural change is observed in the non‐metallized regions of the annealed a‐Si:H film, which has a recombination velocity of 48 cm/s before and after annealing. Copyright © 2004 John Wiley & Sons, Ltd.