Using Element Birth and Death Technique in Modeling Cumulative Molded Substrate Expansion before Singulation

Semiconductor packages are commonly assembled and molded in array format on a substrate strip before they are singulated into individual units. However, cumulative substrate expansion causes problems such as machine vacuum error or misaligned cut during singulation if the substrate expansion is not factored in. This study uses element birth and death technique in modeling the overall expansion of the molded substrate strip so that the predicted expansion could be considered in the singulation tooling design offsets. The expansion of the substrate was modeled with the different package assembly processes and thermal conditions. Modeling results showed that there is a cumulative increase in the length of the substrate as it passes through the different processes. The results are in agreement with actual substrate expansion prior to package singulation. This would not be captured when simulation is done only for the molded substrate without considering the cumulative contribution of the preceding processes. With the element birth and death technique in process-based thermomechanical modeling, substrate expansion could already be forecasted, and package assembly problems avoided.

Molecular Biology of the WWOX Gene That Spans Chromosomal Fragile Site FRA16D

It is now more than 20 years since the FRA16D common chromosomal fragile site was characterised and the WWOX gene spanning this site was identified. In this time, much information has been discovered about its contribution to disease; however, the normal biological role of WWOX is not yet clear. Experiments leading to the identification of the WWOX gene are recounted, revealing enigmatic relationships between the fragile site, its gene and the encoded protein. We also highlight research mainly using the genetically tractable model organism Drosophila melanogaster that has shed light on the integral role of WWOX in metabolism. In addition to this role, there are some particularly outstanding questions that remain regarding WWOX, its gene and its chromosomal location. This review, therefore, also aims to highlight two unanswered questions. Firstly, what is the biological relationship between the WWOX gene and the FRA16D common chromosomal fragile site that is located within one of its very large introns? Secondly, what is the actual substrate and product of the WWOX enzyme activity? It is likely that understanding the normal role of WWOX and its relationship to chromosomal fragility are necessary in order to understand how the perturbation of these normal roles results in disease.

Concentration of active sludge in the aeration reactors

The purpose of the paper was to study the dehydrogenase activity (DHA) of activated sludge in aeration tank. The article describes a change in enzyme activity, (dehydrogenase activity of sludge-DHA) of activated sludge while various time of aeration as well as various dose in sludge of aeration tank. Assessment changes enzyme activity were done on two indicators - on DHAor. (original dehydrogenase activity of sludge) and DHAH2O (dehydrogenase sludge activity with tap water). In the first case - DHA with the actual substrate, in the second case - DHA with poorly concentrated substrate. The work was performed on a pilot installation consisting of four models of aeration tanks blocked with sedimentation tanks, on a real city waste water. Working doses of sludge in biological wastewater treatment process was ranged from 2 to 6 g/l, time of aeration in aeration tanks changed from 3.5. up to 0.8 hours. Experimental studies have shown that regardless of the size of working sludge dose in aeration tank character of changes DHA or and DHAH2O is identical.

Moisture Content Measurements of Green Roof Substrates Using Two Dielectric Sensors

Little is known about the accuracy of soil moisture dielectric sensors in coarse-textured root zones and green roof substrates. In the present study, the accuracy of two dielectric sensors of different technologies (frequency domain and time domain dielectric sensor) in measuring moisture content was investigated in six coarse-textured green roof substrates. Calibration equations were developed for both sensors, and the effect of electrical conductivity (EC) on substrate moisture content calculation was determined. It was found that for frequency domain sensor the relationship between dielectric permittivity square root () and actual substrate moisture content (θm) was strongly linear for all tested substrates. However, for each substrate a distinct specific calibration equation of was required. The correlation between substrate permittivity and EC was linear for frequency domain sensor for all moisture levels (0% to 35%). In the case of time domain sensor, each green roof substrate was also described from a different calibration curve between actual substrate moisture content and period of time that was recorded by the device. It was found that their relationship was quadratic for all substrates. In addition, time domain sensor output responded in a quadratic manner to increasing levels of EC. This response was found to interact with actual substrate moisture content as well. It was concluded that the most reliable results for moisture content determination of the coarse-textured green roof substrates were obtained by substrate-specific calibration curves for both dielectric sensors.

Ammonium Transport by the Erythrocyte Rh-Associated Protein.

The erythrocyte Rh and Rh-associated (RhAG) proteins have distant sequence identity to a family of ammonium transporters found in yeast and bacteria. We previously showed that RhAG mediates movement of ammonium when expressed in yeast and in Xenopus oocytes. Importantly, these are the first mammalian proteins found to transport ammonium as a principal substrate. Elucidation of the mechanism and actual substrate(s) transported (protonated NH4+ or unprotonated NH3, or both) is important to understand their role in elimination of ammonium, proton recycling, and their impact on cellular pH and acid/base regulation. Functional characterization revealed that uptake was independent of the membrane potential and the Na+ gradient, but was dramatically stimulated by raising extracellular pH or lowering intracellular pH. This suggested that uptake was coupled to an outwardly directed H+ gradient and led us to hypothesize that RhAG might function by an H+-coupled, counter-transport mechanism. To further define the mechanism and actual substrate transported, RhAG-expressing oocytes were exposed to varying concentrations of NH4+ with constant NH3, and vice versa, by manipulation of the NH4Cl concentration and the pH of the buffer. A voltage-ramping protocol was used to evaluate changes in membrane conductance and reverse potential to measure membrane depolarization. Radioactive flux uptake of 14C-methylammonium, an analogue of ammonium, was used to measure transport. In the presence of substrate in the physiologic range (20 uM-500 uM), RhAG-mediated transport responded to the concentration of protonated NH4+ rather than the amount of unprotonated NH3 present. Currents in RhAG-expressing oocytes did not differ from water-injected controls. No significant changes in membrane conductance or membrane depolarization and reverse potential were observed. Taken together these data support a role for RhAG in the electronuetral transport of NH4+ by exchange with H+, and for erythrocytes in the maintenance of total blood ammonia levels. Sequestration of ammonium by erythrocytes would keep blood plasma levels low, preventing exposure of cells to toxic levels. Erythrocytes are ideally postioned to then transport ammonium to be exchanged in the liver and kidney, where other Rh-related proteins (RhBG and RhCG) are expressed.

The sulfane sulfur of persulfides is the actual substrate of the sulfur-oxidizing enzymes from Acidithiobacillus and Acidiphilium spp.

To identify the actual substrate of the glutathione-dependent sulfur dioxygenase (EC 1.13.11.18) elemental sulfur oxidation of the meso-acidophilic Acidithiobacillus thiooxidans strains DSM 504 and K6, Acidithiobacillus ferrooxidans strain R1 and Acidiphilium acidophilum DSM 700 was analysed. Extraordinarily high specific sulfur dioxygenase activities up to 460 nmol min−1 (mg protein)−1 were found in crude extracts. All cell-free systems oxidized elemental sulfur only via glutathione persulfide (GSSH), a non-enzymic reaction product from glutathione (GSH) and elemental sulfur. Thus, GSH plays a catalytic role in elemental sulfur activation, but is not consumed during enzymic sulfane sulfur oxidation. Sulfite is the first product of sulfur dioxygenase activity; it further reacted non-enzymically to sulfate, thiosulfate or glutathione S-sulfonate (). Free sulfide was not oxidized by the sulfur dioxygenase. Persulfide as sulfur donor could not be replaced by other sulfane-sulfur-containing compounds (thiosulfate, polythionates, bisorganyl-polysulfanes or monoarylthiosulfonates). The oxidation of H2S by the dioxygenase required GSSG, i.e. the disulfide of GSH, which reacted non-enzymically with sulfide to give GSSH prior to enzymic oxidation. On the basis of these results and previous findings a biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp. is proposed.

OPTIMAL ALGORITHMS FOR SUBSTRATE TESTING IN MULTI-CHIP MODULES

Multi-chip module (MCM) packaging techniques present several new technical challenges, notably substrate testing. We formulate MCM substrate testing as a problem of connectivity verification in trees via k-probes, and present a linear-time algorithm which computes a minimum set of probes achieving complete open fault coverage. Since actual substrate testing also involves scheduling probe operations, we formulate efficient probe scheduling as a special type of metric traveling salesman optimization and give a provably-good heuristic. Empirical results using both random and industry benchmarks demonstrate reductions in testing costs of up to 21% over previous methods. We conclude with generalizations to alternate probe technologies and several open problems.