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The performance of the usual diffused silicon piezoresistive pressure sensors for pressure measurement in high temperature environments is affected by the failure of PN junction isolation, the expansion of silicon oil in packaging structure, and other factors. This study proposed an all-solid-state packaging structure based on silicon/glass/kovar alloy bonding to modify the poor temperature tolerance of silicon oil in the conventional packaging structure of high temperature silicon piezoresistive pressure sensors. Micro-electromechanical system processes, including etching, oxidation, and sputtering, were applied to prepare a high-temperature pressure-sensitive chip based on the smart-cut silicon on insulator wafer. The interconnection of piezoresistors was realized with Ti/Pt/Au multilayer metallization composite electrodes. Silicon/glass, glass/kovar alloy pressure pipes were sealed through the electrostatic bonding process. The electron beam welding process was used to realize the solid-state connection between pressure pipes and sockets, and the sealing condition and performance of the sensor were verified by scanning electron microscope and experiments. Results show that the bonding interfaces between silicon wafer/glass/pressure pipes are good, when a pressure from 0 to 6.0 MPa is applied from 0 °C to 300 °C, the sensitivity is approximately 200 mV/MPa, the nonlinearity is less than 0.59‰FS, the repeatability is less than 0.04‰FS at 300 °C, and the sensitivity temperature drift is less than -0.133 mV/(MPa·°C). This study provides a certain reference for the pressure measurement of silicon piezoresistive pressure sensors in harsh high-temperature environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: In recent years, extensive studies have been performed on magnetite nanoparticles (MNPs) and their applications, which have shown the current project to be one of the major applications by laboratory results. METHODS: The nanoparticles synthesized in this project were deposited by the co-precipitation method, which structure was identified by analyzers such as SEM, FT-IR, and EDX. The aim of this project is the adsorption and fixation of biomolecule (BSA (bovine serum albumin) protein on the surface of magnetic nanoparticles. RESULTS: The adsorption results by electrophoresis and spectrophotometric analyzers showed an absorption rate above 55% ie; 55% of the protein is fixed on the MNPs nanoparticles. This absorption is due to the high level of functionality of magnetic nanoparticles for adsorption of protein. The results of the EDX analysis also show the possible electrostatic bonding between the nanoparticles and the protein, this is derived from -OH with -NH2 groups of the nanobiocompound (MNPs /protein). After bonding, the two are easily separated. CONCLUSION: In this project, the Fe3O4 nanoparticles was synthesized and identified by SEM, FT-IR, and EDX analyzers and finally reacted with the BSA protein (for the absorption of protein on MNPs) under experimental conditions at a standard temperature of 25° C. The results showed that about 55% of the protein was fixed on magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

HIV-1 Gag is a large multidomain poly-protein with flexible unstructured linkers connecting its globular subdomains. It is compact when in solution but assumes an extended conformation when assembled within the immature HIV-1 virion. Here, we use molecular dynamics (MD) simulations to quantitatively characterize the intra-domain interactions of HIV-1 Gag. We find that the matrix (MA) domain and the C-terminal subdomain CActd of the CA capsid domain can form a bound state. The bound state, which is held together primarily by interactions between complementary charged and polar residues, stabilizes the compact state of HIV-1 Gag. We calculate the depth of the attractive free energy potential between the MA/ CActd sites and find it to be about three times larger than the dimerization interaction between the CActd domains. Sequence analysis shows high conservation within the newly-found intra-Gag MA/CActd binding site, as well as its spatial proximity to other well known elements of Gag –such as CActd’s SP1 helix region, its inositol hexaphosphate (IP6) binding site and major homology region (MHR), as well as the MA trimerization site. Our results point to a high, but yet undetermined, functional significance of the intra-Gag binding site. Recent biophysical experiments that address the binding specificity of Gag are interpreted in the context of the MA/CActd bound state, suggesting an important role in selective packaging of genomic RNA by Gag. [ABSTRACT FROM AUTHOR]

With the rapid development of small functional mobile electronic devices, the importance of preparing a flexible, long-life, high-stability device to replace traditional rigid electronic devices has become more prominent. Electrostatic bonding is an advanced material joining technology and exhibits enormous potential m the packaging of flexible devices, which has advantages of high connection strength* good sealing, low bonding temperature, and connection of dissimilar materials. The traditional polymer solid electrolyte has low room-temperature ionic conductivity and poor mechanical properties* which cannot be used well m the electrostatic bonding, and also restricts the application of electrostatic bonding m the preparation and packaging of flexible devices. The unique micro-phase separation structure of polyurethane exhibits good physical and chemical properties. The characteristics of diversified carrier channels, designable soft segments, and a large amount of polar groups of dissociating lithium salt make it an ideal solid electrolyte matrix material. In the paper* four aspects of the optimization of the molecular structure and preparation of polyurethane matrix materials were reviewed, aiming at improving the room temperature ionic conductivity and mechanical properties* which was suitable for flexible device packaging with electrostatic bonding. [ABSTRACT FROM AUTHOR]

Stone fish is an under-utilized sea cucumber with many health benefits. Hydrolysates with strong ACE-inhibitory effects were generated from stone fish protein under the optimum conditions of hydrolysis using bromelain and fractionated based on hydrophobicity and isoelectric properties of the constituent peptides. Five novel peptide sequences with molecular weight (mw) < 1000 daltons (Da) were identified using LC-MS/MS. The peptides including Ala-Leu-Gly-Pro-Gln-Phe-Tyr (794.44 Da), Lys-Val-Pro-Pro-Lys-Ala (638.88 Da), Leu-Ala-Pro-Pro-Thr-Met (628.85 Da), Glu-Val-Leu-Ile-Gln (600.77 Da) and Glu-His-Pro-Val-Leu (593.74 Da) were evaluated for ACE-inhibitory activity and showed IC50 values of 0.012 mM, 0.980 mM, 1.310 mM, 1.440 mM and 1.680 mM, respectively. The ACE-inhibitory effects of the peptides were further verified using molecular docking study. The docking results demonstrated that the peptides exhibit their effect mainly via hydrogen and electrostatic bond interactions with ACE. These findings provide evidence about stone fish as a valuable source of raw materials for the manufacture of antihypertensive peptides that can be incorporated to enhance therapeutic relevance and commercial significance of formulated functional foods. [ABSTRACT FROM AUTHOR]

Golgi α-mannosidase II (GMII) is a glycoside hydrolase playing a crucial role in the N-glycosylation pathway. In various tumour cell lines, the distribution of N-linked sugars on the cell surface is modified and correlates with the progression of tumour metastasis. GMII therefore is a possible molecular target for anticancer agents. Here, we describe the identification of a non-competitive GMII inhibitor using computer-aided drug design methods including identification of a possible allosteric binding site, pharmacophore search and virtual screening. [ABSTRACT FROM AUTHOR]

Oxidized coal is difficult-to-float using conventional diesel as the collector due to the abundant oxygen-containing groups on coal surface. In this study, a short-chain cationic amine, n-octylamine, was added into diesel in 1:4 ratio for enhancing oxidized coal flotation. X-ray photoelectron spectroscopy (XPS) was used to identify the interaction mechanism between diesel-n-octylamine mixture (DO) and oxidized coal. The results showed that the flotation yield using 500 g/t DO mixture was much higher than that of using 2000 g/t diesel under a similar ash content of clean coal. The addition of n-octylamine was proven to be an effective way to lower the oily collector consumption in oxidized coal flotation. XPS showed that electrostatic bonding between n-octylamine and negative-charged hydrophilic sites on oxidized coal surface was responsible for the enhancement of flotation recovery using DO as the collector. [ABSTRACT FROM AUTHOR]

The inhibition of the hERG potassium channel is closely related to the prolonged QT interval, and thus assessing this risk could greatly facilitate the development of therapeutic compounds and the withdrawal of hazardous marketed drugs. The recent increase in SAR information about hERG inhibitors in public databases has led to many successful applications of machine learning techniques to predict hERG inhibition. However, most of these reports constructed their prediction models based on only one SAR database because the differences in the data format and ontology hindered the integration of the databases. In this study, we curated the hERG-related data in ChEMBL, PubChem, GOSTAR, and hERGCentral, and integrated them into the largest database about hERG inhibition by small molecules. Assessment of structural diversity using Murcko frameworks revealed that the integrated database contains more than twice as many chemical scaffolds for hERG inhibitors than any of the individual databases, and covers 18.2% of the Murcko framework-based chemical space occupied by the compounds in ChEMBL. The database provides the most comprehensive information about hERG inhibitors and will be useful to design safer compounds for drug discovery. The database is freely available at . [ABSTRACT FROM AUTHOR]

In this study, we report a detailed experimental, binding free energy calculation and molecular dynamics (MD) simulation investigation of the interactions of carboxylic-functionalized multi-walled carbon nanotubes (COOH-f-MWCNTs) with porcine trypsin (pTry). The enzyme exhibits decreased thermostability at 330K in the presence of COOH-f-MWCNTs. Furthermore, the activity of pTry also decreases in the presence of COOH-f-MWCNTs. The restricted diffusion of the substrate to the active site of the enzyme was observed in the experiment. The MD simulation analysis suggested that this could be because of the blocking of the S1 pocket of pTry, which plays a vital role in the substrate selectivity. The intrinsic fluorescence of pTry is quenched with increase in the COOH-f-MWCNTs concentration. Circular dichroism (CD) and UV–visible absorption spectroscopies indicate the ability of COOH-f-MWCNTs to experience conformational change in the native structure of the enzyme. The binding free energy calculations also show that electrostatics, π-cation, and π-π stacking interactions play important roles in the binding of the carboxylated CNTs with pTry. The MD simulation results demonstrated that the carboxylated CNTs adsorb to the enzyme stronger than the CNT without the–COOH groups. Our observations can provide an example of the nanoscale toxicity of COOH-f-MWCNTs for proteins, which is a critical issue for in vivo application of COOH-f-MWCNTs. [ABSTRACT FROM AUTHOR]

The fatty acid-binding proteins L-BABP and Rep1-NCXSQ bind to anionic lipid membranes by electrostatic interactions. According to Molecular Dynamics (MD) simulations, the interaction of the protein macrodipole with the membrane electric field is a driving force for protein binding and orientation in the interface. To further explore this hypothesis, we studied the interactions of these proteins with cationic lipid membranes. As in the case of anionic lipid membranes, we found that both proteins, carrying a negative as well as a positive net charge, were bound to the positively charged membrane. Their major axis, those connecting the bottom of the β-barrel with the α-helix portal domain, were rotated about 180 degrees as compared with their orientations in the anionic lipid membranes. Fourier transform infrared (FTIR) spectroscopy of the proteins showed that the positively charged membranes were also able to induce conformational changes with a reduction of the β-strand proportion and an increase in α-helix secondary structure. Fatty acid-binding proteins (FABPs) are involved in several cell processes, such as maintaining lipid homeostasis in cells. They transport hydrophobic molecules in aqueous medium and deliver them into lipid membranes. Therefore, the interfacial orientation and conformation, both shown herein to be electrostatically determined, have a strong correlation with the specific mechanism by which each particular FABP exerts its biological function. [ABSTRACT FROM AUTHOR]

The current model of binding of the antitumor antibiotic olivomycin A (1) to GC-rich DNA regions presumes that coordination of the magnesium divalent cation with drug dimers is necessary for binding of 1 into the minor groove of the DNA duplex. Previously we have synthesized the derivatives of 1 termed ‘short acid’ (2) and its N,N-dimethylaminoethylamide (3). The latter compound demonstrated an improved tolerance in vivo compared to 1 and good therapeutic potency in animal models. We herein report that compound 3 is able to form stable complexes with DNA in the absence of Mg2+, in striking contrast to 1 whose binding to the DNA absolutely requires Mg2+. The mode of binding of 3 to DNA is similar in the presence or absence of Mg2+ as determined by circular dichroism. The affinity to DNA of 3 in Mg2+-free solution was similar to that of 1 or 3 in the presence of Mg2+ at low ionic strength. Non-electrostatic contributions to total free energy of binding of 1 and 3 to DNA were comparable for Mg2+-free complexes. Our data strongly suggest that electrostatic interaction of the positively charged 3 can compensate for the absence of divalent ions in complexes with DNA. This new property of the olivomycin A derivative expands the mechanistic knowledge of the modes of interaction with DNA of small molecular weight drug candidates. [ABSTRACT FROM AUTHOR]

1,3,4-Thiadiazole and sugar-derived molecules have proven to be promising agrochemicals with growth promoting, insecticidal and fungicidal activities. In the research field of agricultural fungicide, applying union of active group we synthesized a new set of 1,3,4-thiadiazole xylofuranose derivatives and all of the compounds were characterized by 1H NMR and HRMS. In precise toxicity measurement, some of compounds exhibited more potent fungicidal activities than the most widely used commercial fungicide Chlorothalonil, promoting further research and development. Based on our experimental data, 3D-QSAR (three-dimensional quantitative structure-activity relationship) was established and investigated using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques, helping to better understand the structural requirements of lead compounds with high fungicidal activity and environmental compatibility. [ABSTRACT FROM AUTHOR]

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease with dysfunctional α-motor neurons in the anterior horn of the spinal cord. SMA is caused by loss (∼95% of SMA cases) or mutation (∼5% of SMA cases) of the survival motor neuron 1 gene SMN1. As the product of SMN1, SMN is a component of the SMN complex, and is also involved in the biosynthesis of the small nuclear ribonucleoproteins (snRNPs), which play critical roles in pre-mRNA splicing in the pathogenesis of SMA. To investigate how SMA-linked mutations of SMN1 lead to structural/functional deficiency of SMN, a set of computational analysis of SMN-related structures were conducted and are described in this article. Of extraordinary interest, the structural analysis highlights three SMN residues (Asp44, Glu134 and Gln136) with SMA-linked missense mutations, which cause disruptions of electrostatic interactions for Asp44, Glu134 and Gln136, and result in three functionally deficient SMA-linked SMN mutants, Asp44Val, Glu134Lys and Gln136Glu. From the computational analysis, it is also possible that SMN’s Lys45 and Asp36 act as two electrostatic clips at the SMN-Gemin2 complex structure interface. [ABSTRACT FROM AUTHOR]

PUMA, which belongs to the BH3-only protein family, is an intrinsically disordered protein (IDP). It binds to its cellular partner Mcl-1 through its BH3 motif, which folds upon binding into an α helix. We have applied a structure-based coarse-grained model, with an explicit Debye—Hückel charge model, to probe the importance of electrostatic interactions both in the early and the later stages of this model coupled folding and binding process. This model was carefully calibrated with the experimental data on helical content and affinity, and shown to be consistent with previously published experimental data on binding rate changes with respect to ion strength. We find that intramolecular electrostatic interactions influence the unbound states of PUMA only marginally. Our results further suggest that intermolecular electrostatic interactions, and in particular non-native electrostatic interactions, are involved in formation of the initial encounter complex. We are able to reveal the binding mechanism in more detail than is possible using experimental data alone however, and in particular we uncover the role of non-native electrostatic interactions. We highlight the potential importance of such electrostatic interactions for describing the binding reactions of IDPs. Such approaches could be used to provide predictions for the results of mutational studies. [ABSTRACT FROM AUTHOR]

The use of alkali glass in micromechanical sensors, specifically, accelerometers, is shown. Alkali glass is used in the sensitive elements of the indicated devices. The main technological operation in the assembly of such sensitive elements is electrostatic bonding, also known as the anodic bonding. In this process a number of complex physical effects occur in the glass. Reliable functioning of the fabricated devices depends on the quality of the execution of the parts made of alkali glass and silicon. [ABSTRACT FROM AUTHOR]

Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21–22 kcal/mol, in good agreement with experiment (18–19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are accessible, for example in other transferases. [ABSTRACT FROM AUTHOR]

The receptors tyrosine kinases (RTKs) for the colony stimulating factor-1, CSF-1R, and for the stem cell factor, SCFR or KIT, are important mediators of signal transduction. The abnormal function of these receptors, promoted by gain-of-function mutations, leads to their constitutive activation, associated with cancer or other proliferative diseases. A secondary effect of the mutations is the alteration of receptors’ sensitivity to tyrosine kinase inhibitors, compromising effectiveness of these molecules in clinical treatment. In particular, the mutation V560G in KIT increases its sensitivity to Imatinib, while the D816V in KIT, and D802V in CSF-1R, triggers resistance to the drug. We analyzed the Imatinib binding affinity to the native and mutated KIT (mutations V560G, S628N and D816V) and CSF-1R (mutation D802V) by using molecular dynamics simulations and energy calculations of Imatinib•target complexes. Further, we evaluated the sensitivity of the studied KIT receptors to Imatinib by measuring the inhibition of KIT phosphorylation. Our study showed that (i) the binding free energy of Imatinib to the targets is highly correlated with their experimentally measured sensitivity; (ii) the electrostatic interactions are a decisive factor affecting the binding energy; (iii) the most deleterious impact to the Imatinib sensitivity is promoted by D802V (CSF-1R) and D816V (KIT) mutations; (iv) the role of the juxtamembrane region, JMR, in the imatinib binding is accessory. These findings contribute to a better description of the mutation-induced effects alternating the targets sensitivity to Imatinib. [ABSTRACT FROM AUTHOR]

To overcome various concerns caused by scaling down the device size in future Large Scale Integrated Circuits (LSIs), it is indispensable to introduce a new concept of heterogeneous 3-D integration in which various kinds of device chips with different sizes, different devices, and different materials are vertically stacked. To achieve such heterogeneous 3-D integration, a key technology of self-assembly and electrostatic bonding has been developed. Exploring new devices for the Internet of Things, we have fabricated several kinds of heterogeneous 3-D LSIs called superchip by stacking compound semiconductor device chip, photonic device chip, and spintronic device chip on CMOS device chips using self-assembly and electrostatic bonding. Furthermore, a new system integration technology using a large-area substrate has been developed to reduce the cost of 2.5-D/3-D system module. A 3-D-stacked image sensor system module for automatic driving vehicle has been fabricated using this technology. [ABSTRACT FROM PUBLISHER]

Aedes aegypti, Aedes albopictus and Culex quinquefasciatus are vectors of dengue fever and West Nile virus diseases. This study was conducted to determine the toxicity, mechanism of action and the binding interaction of three active phenylpropanoids from Piper sarmentosum (Piperaceae) toward late 3rd or early 4th larvae of above vectors. A bioassay guided-fractionation on the hexane extract from the roots of Piper sarmentosum led to the isolation and identification of three active phenylpropanoids; asaricin 1, isoasarone 2 and trans-asarone 3. The current study involved evaluation of the toxicity and acetylcholinesterase (AChE) inhibition of these compounds against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae. Asaricin 1 and isoasarone 2 were highly potent against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae causing up to 100% mortality at ≤ 15 μg/mL concentration. The ovicidal activity of asaricin 1, isoasarone 2 and trans-asarone 3 were evaluated through egg hatching. Asaricin 1 and isoasarone 2 showed potent ovicidal activity. Ovicidal activity for both compounds was up to 95% at 25μg/mL. Asaricin 1 and isoasarone 2 showed strong inhibition on acetylcholinesterase with relative IC50 values of 0.73 to 1.87 μg/mL respectively. These findings coupled with the high AChE inhibition may suggest that asaricin 1 and isoasarone 2 are neuron toxic compounds toward Aedes aegypti, Aedes albopictus and Culex quinquefasciatus. Further computational docking with Autodock Vina elaborates the possible interaction of asaricin 1 and isoasarone 2 with three possible binding sites of AChE which includes catalytic triads (CAS: S238, E367, H480), the peripheral sites (PAS: E72, W271) and anionic binding site (W83). The binding affinity of asaricin 1 and isoasarone 2 were relatively strong with asaricin 1 showed a higher binding affinity in the anionic pocket. [ABSTRACT FROM AUTHOR]

The γ-aminobutyric acid type A receptor (GABAA-R) is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a ‘funnel’ that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site. [ABSTRACT FROM AUTHOR]

LacI is commonly used as a model to study the protein-DNA interaction and gene regulation. The headpiece of the lac-repressor (LacI) protein is an ideal system for investigation of nonspecific binding of the whole LacI protein to DNA. The hinge region of the headpiece has been known to play a key role in the specific binding of LacI to DNA, whereas its role in nonspecific binding process has not been elucidated. Here, we report the results of explicit solvent molecular dynamics simulation and continuum electrostatic calculations suggesting that the hinge region strengthens the nonspecific interaction, accounting for up to 50% of the micro-dissociation free energy of LacI from DNA. Consequently, the rate of microscopic dissociation of LacI from DNA is reduced by 2~3 orders of magnitude in the absence of the hinge region. We find the hinge region makes an important contribution to the electrostatic energy, the salt dependence of electrostatic energy, and the number of salt ions excluded from binding of the LacI-DNA complex. [ABSTRACT FROM AUTHOR]

HIV-1 gp41 facilitates the viral fusion through a conformational switch involving the association of three C-terminal helices along the conserved hydrophobic grooves of three N-terminal helices coiled-coil. The control of these structural rearrangements is thought to be central to HIV-1 entry and, therefore, different strategies of intervention are being developed. Herewith, we describe a procedure to simulate the folding of an HIV-1 gp41 simplified model. This procedure is based on the construction of plausible conformational pathways, which describe protein transition between non-fusogenic and fusogenic conformations. The calculation of the paths started with 100 molecular dynamics simulations of the non-fusogenic conformation, which were found to converge to different intermediate states. Those presenting defined criteria were selected for separate targeted molecular dynamics simulations, subjected to a force constant imposing a movement towards the gp41 fusogenic conformation. Despite significant diversity, a preferred sequence of events emerged when the simulations were analyzed in terms of the formation, breakage and evolution of the contacts. We pointed out 29 residues as the most relevant for the movement of gp41; also, 2696 possible interactions were reduced to only 48 major interactions, which reveals the efficiency of the method. The analysis of the evolution of the main interactions lead to the detection of four main behaviors for those contacts: stable, increasing, decreasing and repulsive interactions. Altogether, these results suggest a specific small cavity of the HIV-1 gp41 hydrophobic groove as the preferred target to small molecules. [ABSTRACT FROM AUTHOR]

The flat-membrane silicon on insulator (SOI) high-temperature piezoresistive pressure sensitive silicon chip has been developed using MEMS (micro electro-mechanical system) technology. It was packaged on the borosilicate glass ring by electrostatic bonding process, thus the inverted-cup elastic-sensitive unit was produced. The influence of the alignment error between the silicon chip and glass ring on the nonlinearity of the pressure sensitive silicon chip was analyzed. The experiments were performed to verify the effect of the electrostatic bonding process on the temperature properties of the pressure sensitive silicon chip, and obtained the characteristics of the fabricated high-temperature pressure sensor. According to the theoretical and experimental results, the alignment error has a great impact on the nonlinearity of the silicon chip, while the electrostatic bonding process has less effect on the zero drifts and thermal zero drifts of the silicon chip. The fabricated high-temperature pressure sensor has fine performances to meet the requirements of engineering applications. [ABSTRACT FROM AUTHOR]

Widespread use of tributyltin (TBT) poses a serious environmental problem. Adsorption by black carbon (BC) may strongly affect its behavior. The adsorption of TBT to well characterized soot and two charcoals with specific surface area in the range of 62–111m2 g−1 have been investigated with main focus on pH effects. The charcoals but not soot possess acidic functional groups. TBT adsorption reaches maximum at pH 6–7 for charcoals, and at pH>6 for soot. Soot has between 1.5 and 15 times higher adsorption density (0.09–1.77μmolm−2) than charcoals, but charcoals show up to 17 times higher sorption affinities than soot. TBT adsorption is successfully described by a new pH-dependent dual Langmuir model considering electrostatic and hydrophobic adsorption, and pH effects on TBT speciation and BC surface charge. It is inferred that strong sorption of the TBTOH species to BC may affect TBT toxicity. [Copyright &y& Elsevier]

Originally developed in the late 1960s, anodic bonding, also known as electrostatic bonding, field-assisted bonding or Mallory bonding, has become one of the most important silicon packaging techniques. Despite its industrial relevance the bonding mechanism is mainly only qualitatively understood and is almost solely applied to the bonding of silicon to Pyrex glass. The objective of the present paper is to review the current state of knowledge of the anodic bonding process. Possible material combinations and current scientific and industrial applications of this bonding technique are reviewed. The various aspects of the bonding process, such as the creation of intimate contact, the cation movement in the glass and the interfacial chemical reactions, are discussed in detail and related to the external current measured during bonding to describe the bonding process quantitatively. A better understanding of the process itself should help not only to improve the process control and the quality of devices, but also to broaden the application of this successful bonding technique to more challenging designs, to smaller device sizes and to systems other than silicon–Pyrex glass. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication and characterization of a thermal ink jet (TIJ) printhead suitable for high speed and high-quality printing. The printhead has been fabricated by dicing the bonded wafer, which consists of a bubble generating heater plate and a Si channel plate. The Si channel plate consists of an ink chamber and an ink inlet formed by KOR etching, and a nozzle formed by inductively couple plasma reactive ion etching (ICP RIE). The nozzle formed by RIE has squeezed structures, which contribute to high-energy efficiency of drop ejector and, therefore, successful ejection of small ink drop. The nozzle also has a dome-like structure called channel pit, which contributes to high jetting frequency and high-energy efficiency. These two wafers are directly bonded using electrostatic bonding of full-cured polyimide to Si. The adhesive-less bonding provided an ideal shaped small nozzle orifice. Use of the same material (Si substrate) in heater plate and channel plate enables the fabrication of high precision long printhead because no displacement and delamination occur, which are caused by the difference in thermal expansion coefficient between the plates. With these technologies, we have fabricated a 1" long printhead with 832 nozzles having 800 dots per inch (dpi) resolution and a 4 pl. ink drop volume. [ABSTRACT FROM AUTHOR]

Single and dual phase procedures are developed for bonding silicon and 7740 Pyrex wafers in nitrogen at the atmospheric pressure and under partial vacuum. Their efficiencies are evaluated by comparison of the atomic bond populations. It is shown that at 105 Pa, 200 V and 500 °C almost optimum populations are obtained. Under vacuum, less dense populations and less uniform distributions are formed. The use of an aluminium layer deposited on the Pyrex surface in contact with the heating plate and the silicon heating by an electric lamp improve significantly the population characteristics. At 100 Pa, these modifications limit the decrease in the minimum bond density to 22% if the potential difference equals 250 V and to 13% at 750 V. The addition of an in situ treatment at the atmospheric pressure reduces the difference to 4% and yields almost optimum bond populations. [Copyright &y& Elsevier]