Cosmological production of H_2 before the formation of the first galaxies

Previous calculations of the pregalactic chemistry have found that a small amount of H_2, x[H_2]=n[H_2]/n[H] = 2.6e-6, is produced catalytically through the H^-, H_2^+, and HeH^+ mechanisms. We revisit this standard calculation taking into account the effects of the nonthermal radiation background produced by cosmic hydrogen recombination, which is particularly effective at destroying H^- via photodetachment. We also take into consideration the non-equilibrium level populations of H_2^+, which occur since transitions among the rotational-vibrational levels are slow compared to photodissociation. The new calculation predicts a final H_2 abundance of x[H_2] = 6e-7 for the standard cosmology. This production is due almost entirely to the H^- mechanism, with ~1 per cent coming from HeH^+ and ~0.004 per cent from H_2^+. We evaluate the heating of the diffuse pregalactic gas from the chemical reactions that produce H_2 and from rotational transitions in H_2, and find them to be negligible.Comment: 13 pages, 5 figures, MNRAS submitte

Multiplicity of fibronectin-binding alpha V integrin receptors in colorectal cancer.

Current data from in vitro and in vivo animal models indicate that fibronectin-binding integrin receptors expressed by colon cancer cells may regulate tumour growth. While individual members of the beta 1 subfamily of integrins have now been clearly identified in colorectal cancer, little information exists with respect to the alpha V subfamily. In the present study we show that alpha V can associate with multiple and different beta subunits capable of binding fibronectin in this tumour type. This is likely to have functional implications for growth and spread of colorectal cancer

Low cost solar array project 1: Silicon material

The low cost production of silicon by deposition of silicon from a hydrogen/chlorosilane mixture is described. Reactor design, reaction vessel support systems (physical support, power control and heaters, and temperature monitoring systems) and operation of the system are reviewed. Testing of four silicon deposition reactors is described, and test data and consequently derived data are given. An 18% conversion of trichlorosilane to silicon was achieved, but average conversion rates were lower than predicted due to incomplete removal of byproduct gases for recycling and silicon oxide/silicon polymer plugging of the gas outlet. Increasing the number of baffles inside the reaction vessel improved the conversion rate. Plans for further design and process improvements to correct the problems encountered are outlined

Thick silicon growth techniques

Hall mobility measurements on a number of single crystal silicon ribbons grown from graphite dies have shown some ribbons to have mobilities consistent with their resistivities. The behavior of other ribbons appears to be explained by the introduction of impurities of the opposite sign. Growth of a small single crystal silicon ribbon has been achieved from a beryllia dia. Residual internal stresses of the order of 7 to 18,000 psi have been determined to exist in some silicon ribbon, particularly those grown at rates in excess of 1 in./min. Growth experiments have continued toward definition of a configuration and parameters to provide a reasonable yield of single crystal ribbons. High vacuum outgassing of graphite dies and evacuation and backfilling of growth chambers have provided significant improvements in surface quality of ribbons grown from graphite dies

Extremely low frequency electromagnetic fields and cancer: the epidemiologic evidence.

This paper reviews the epidemiologic evidence that low frequency electromagnetic fields generated by alternating current may be a cause of cancer. Studies examining residential exposures of children and adults and studies of electrical and electronics workers are reviewed. Using conventional epidemiologic criteria for inferring causal associations, including strength and consistency of the relationship, biological plausibility, and the possibility of bias as an explanation, it is concluded that the evidence is strongly suggestive that such radiation is carcinogenic. The evidence is strongest for brain and central nervous system cancers in electrical workers and children. Weaker evidence supports an association with leukemia in electrical workers. Some evidence also exists for an association with melanoma in electrical workers. Failure to find consistent evidence of a link between residential exposures and adult cancers may be attributable to exposure misclassification. Studies so far have used imperfect surrogates for any true biologically effective magnetic field exposure. The resulting exposure misclassification has produced relative risk estimates that understate any true risk

Development of Gene Regulatory Elements for Biosensing Applications

21% of U.S adults experienced mental illnesses in 2020. Nearly 1 in 4 active- duty military personnel showed signs of mental health conditions in 2014 [89]. Mental health can be identified in the body by different biomarkers. These biomarkers potentially could be controlled by riboswitches, which could help mental illnesses and regulate diseases. Riboswitches are desirable in these cases due to responding without affecting vital functions. Riboswitches are located in mRNA and switch “ON” or “OFF” depending on the concentration of a biomarker [13]. In this research, riboswitches were re-engineered to take a known riboswitch and control its response in the presence of a biomarker. This was done by computationally changing PreQ1, a known riboswitch that has the smallest aptamer, and then experimentally testing against biomarkers, dehydroepiandrosterone-sulfate (DHEA-S), Serotonin, Cortisol, Dopamine, Epinephrine, and Norepinephrine. A total of 7 variant riboswitches were tested in this research, 4 created computationally and 3 created in research [53]. The results from these variants showed that variants 1 and 2 had different responses to DHEA-S then the expected PreQ1 response. A dose response test confirmed this by having a downward trend as DHEA-S concentration increased. In conclusion of this research, riboswitches can be re-engineered to have a different response to biomarkers but keep the same structure