We report the enzymatic degradation mechanism of a solution-grown poly[(R)-3-hydroxybutyrate] (P(3HB)) single crystal with an extracellular polyhydroxybutyrate depolymerase purified from Alcaligenes faecalis T1 (PhaZAfa). The P(3HB) single crystals adsorbed on highly ordered pyrolytic graphite were incubated with a wild-type or a hydrolytic-activity-disrupted mutant of PhaZAfa, and morphologica...

Cutting tools are widely used in manufacturing processes and drilling is the most commonly used machining process. Although drill-bits used in drilling may not be expensive, their breakage can cause damage to expensive work piece being drilled and at the same time has major impact on productivity. Predicting drill-bit breakage, therefore, is important in reducing cost and improving productivity...

We develop a simple model of labor market participation, human capital degradation, and re-training. We focus on how non-participation, as a distinct state from unemployment and employment, is determined by the welfare system in interaction with labor market conditions and personal characteristics. We provide a tractable framework to analyze how the decisions to exit the labor force and to miti...

A degradation study of polystyreneepolybutadieneepolystyrene and polyisopreneepolystyrenee polyisoprene in both dichloromethane and hexane solvents is presented. Alternative solvents for metathetic degradation provide the potential for greener chemistry, better selectivity, and control over the products. The catalyst concentration and solvent selection both determine the products formed. The de...

Proteolytic machines powered by ATP hydrolysis bind proteins with specific peptide tags, denature these substrates, and translocate them into a sequestered compartment for degradation. To determine how ATP is used during individual reaction steps, we assayed ClpXP degradation of ssrA-tagged titin variants with different stabilities in native and denatured forms. The rate of ATP turnover was 4-f...

an energy based damage index based on a new nonlinear finite element (fe) approach applicable to rc structures subjected to cyclic, earthquake or monotonic loading is proposed. the proposed method is based on the evaluation of nonlinear local degradation of materials and taking into account of the pseudo-plastic hinge produced in the critical sections of the structure. a computer program is dev...

Our objective in experiments reported here was to identify myofilament proteins of rat hearts either lost or degraded by cardiac ischemia (15- or 60-minute duration) with and without 45 minutes of reperfusion. We correlated these changes with alterations in myofilament sensitivity to Ca2+ and maximum force generation. Protein degradation and loss were assessed by high-performance liquid chromat...

We use single-molecule force spectroscopy to demonstrate that the mechanical stability of the enzyme dihydrofolate reductase (DHFR) is modulated by ligand binding. In the absence of bound ligands, DHFR extends at very low forces, averaging 27 pN, without any characteristic mechanical fingerprint. By contrast, in the presence of micromolar concentrations of the ligands methotrexate, nicotinamide...

Hydroxyl radicals (OH) are involved in the development of reperfusion injury and myocardial failure. In the acute phase of the OH-mediated diastolic dysfunction, increased intracellular Ca(2+) levels and alterations of myofilaments may play a role, but the relative contribution of these systems to myocardial dysfunction is unknown. Intact contracting cardiac trabeculae from rabbits were exposed...