Lattice mismatch and the nature of dissolution in the LPE of Pb-Salt compounds

It is shown experimentally that lattice matching is important in determining the nature of the solid/solution interface behavior during controlled meltback near saturation conditions. We define the lattice matching between a crystalline substrate and a solution via the solid in equilibrium with the solution and in a similar way lattice mismatch conditions can be defined as well. We found that a flat interface is preserved during meltback and regrowth if the solution is lattice matched to the substrate even when they are of different chemical potentials. Meltback and regrowth under matched conditions has been used to form graded-gap heterostructures with flat interfaces. We suggest using undersaturated lattice matched solutions whenever an in situ removal of the top part of a substrate is needed prior to epitaxial growth.     

Liquid phase epitaxy of pbtese lattice-matched to pbsnte

The conditions for liquid phase epitaxial growth of lead telluride selenide on lead tin telluride are presented, and some physical and electrical properties of the epilayers grown are described. The composition and energy gap of the quaternary lead salt compound, lead tin telluride selenide, lattice-matched to lead selenide and to lead-tin telluiride, as determined from published data, is also presented. The growth of PbSnTeSe on PbSnTe is demonstrated.     

Replicative Stress Coincides with Impaired Nuclear DNA Damage Response in COX4-1 Deficiency

Cytochrome c oxidase (COX), a multimeric protein complex, is the final electron acceptor in the mitochondrial electron transfer chain. Primary COX deficiency, caused by mutations in either mitochondrial DNA or nuclear-encoded genes, is a heterogenous group of mitochondrial diseases with a wide range of presentations, ranging from fatal infantile to subtler. We previously reported a patient with primary COX deficiency due to a pathogenic variant in COX4I1 (encoding the common isoform of COX subunit 4, COX4-1), who presented with bone marrow failure, genomic instability, and short stature, mimicking Fanconi anemia (FA). In the present study, we demonstrated that accumulative DNA damage coincided primarily with proliferative cells in the patient’s fibroblasts and in COX4i1 knockdown cells. Expression analysis implicated a reduction in DNA damage response pathways, which was verified by demonstrating impaired recovery from genotoxic insult and decreased DNA repair. The premature senescence of the COX4-1-deficient cells prevented us from undertaking additional studies; nevertheless, taken together, our results indicate replicative stress and impaired nuclear DNA damage response in COX4-1 deficiency. Interestingly, our in vitro findings recapitulated the patient’s presentation and present status.     

Local stiffening effect of 'double deck1 bending strain gauges: part 2

In stress measurement where it is difficult or impossible to access the inside surface of the structure, "double deck" (DD) or "sandwich" bending strain gauges can be used to measure both the membrane and bending strains. A DD gauge consists of a pair of constituent foil gauges which are bonded on the upper and lower surfaces of a plastic base or filling. It is mounted on the external surface of the test specimen to measure the external surface strain, and by extrapolation, the internal surface strain of the. specimen. The. sensitivity of the DD bending gauge increases when the separation between the pair of constituent foil gauges increases. However, this also increases the stiffness of the whole gauge. If the stiffness of the DD gauge is significant compared with that of the plate to which it is attached, the presence of the gauge may cause significant changes in local stiffness and result in errors of strain interpretation. This study is presented in two papers. Part I, appeared in the Feburary 1996 issue of Strain, presented an approximate analytical solution for the local stiffening effect of a DD gauge, and quantifies the errors in the strain measurement. Part 2 (this paper) presents the verification of the. solution using a three-dimensional finite element calculation, a parametric study and a correction method that can be applied easily. The extrapolation errors due to the stiffening effect and random reading noises are also explored. The figure and equation numbers in this part are continuedfrom Part 1, but the reference numbering is specific to Part 2.     

Numerical analysis of silo behavior using non-coaxial models

Granular solids in silos experience considerable principal stress rotations, which result in the non-coaxiality between principal stresses and plastic strain rates. This paper discusses the influences of the use of elastoplastic non-coaxial models for granular solids on predictions of wall pressure distributions in silos by using the finite element method. A well established non-coaxial model in geomechanics, the yield vertex model, is employed. Simulations are performed on a steep hopper characterized with a mass flow and a flat-bottomed silo with a semi-mass flow. The simulations indicate that the non-coaxiality does not influence predictions of wall pressures after filling. On the other hand, the predicted discharge wall pressures with non-coaxial considerations are larger than those without it. Its mechanism is discussed in this paper. The suppressed shear-dilatancy of granular solids in silos leads to a larger increase of normal stress with non-coaxial models.     

RhII-Catalyzed De-symmetrization of Ethane-1,2-dithiol and Propane-1,3-dithiol Yields Metallo-β-lactamase Inhibitors

Diversity-oriented synthesis (DOS) is a rich source for novel lead structures in Medicinal Chemistry. In this study, we present a DOS-compatible method for synthesis of compounds bearing a free thiol moiety. The procedure relies on Rh(II)-catalyzed coupling of dithiols to diazo building blocks. The synthetized library was probed against metallo-β-lactamases (MBLs) NDM-1 and VIM-1. Biochemical and biological evaluation led to identification of novel potent MBL inhibitors with antibiotic adjuvant activity.     

Programmable “Semismart” Sensor: Relevance to Monitoring Antipsychotics

Mental health disorders are complex and poorly understood but would benefit from real‐time chemical analysis capable of assessing a patient's current status, personalizing a therapeutic action, and monitoring compliance. Here, an electrochemical sensor is reported for detecting the antipsychotic drug clozapine which is one of the most effective but under‐utilized drugs for managing schizophrenia. This sensor employs a composite film of multiwalled carbon nanotubes (CNTs) embedded within a matrix of the aminopolysaccharide chitosan. Chitosan allows programmable assembly of the composite film at an electrode address while the CNTs confer electrocatalytic activities that displace interfering serum peaks from the voltage region where clozapine oxidation occurs. Using differential pulse voltammetry, high sensitivities (limit of detection 0.05 × 10^–6m ) are demonstrated for clozapine analysis in buffer. In serum, clozapine sensitivity is reduced by an order of magnitude but still sufficient for clinical analysis. Finally, the detection of clozapine from the serum of a schizophrenia patient is demonstrated without the need for serum pretreatment. In the long term, it is envisioned that the CNT‐chitosan coated electrode could be integrated within a small array of other sensor types to enhance information‐extraction to allow mental health disorders to be better managed and better understood.     

Transformation of the recalcitrant pharmaceutical compound carbamazepine by Pleurotus ostreatus: role of cytochrome P450 monooxygenase and manganese peroxidase

Carbamazepine (CBZ) is an environmentally recalcitrant compound highly stable in soil and during wastewater treatment. In this study, we examined the mechanisms by which the white-rot fungus Pleurotus ostreatus metabolizes CBZ in liquid culture using a physiological approach. P. ostreatus PC9 was grown in media known to support different levels of a multiplicity of enzyme systems such as cytochrome P450 (CYP450) and manganese peroxidase (MnP). When both CYP450 and MnP systems were active, 99% of the added CBZ was eliminated from the solution and transformed to 10,11-epoxycarbamazepine. High removal of CBZ was also obtained when either MnP or CYP450 was active. When both CYP450 and MnP were inactivated, only 10 to 30% of the added CBZ was removed. In this latter system, removal of CBZ might be partially attributed to the activity of versatile peroxidase. P. ostreatus was able to eliminate CBZ in liquid culture even when CBZ was added at an environmentally relevant concentration (1 μg L(-1)). On the basis of our study, we suggest that two families of enzymes are involved in the oxidation of CBZ in liquid culture: MnP in a Mn(2+)-dependent or independent manner and CYP450. Our study also highlights the potential of using P. ostreatus for bioremediation systems.