Evaluation of Quantum Efficiency,Crosstalk, and Surface Recombination in HgCdTe Photon-Trapping Structures

The quantum efficiency (QE) in HgCdTe photovoltaic pixel arrays employing a photon-trapping (PT) structure realized with a periodic array of pillars intended to provide broadband operation was investigated. It was found that the QE depends heavily on the passivation of the pillar surface. This is due to the presence of large fixed positive charge on the surface of pillars passivated with anodic oxide. A three-dimensional numerical simulation model was used to study the effect of the surface charge density and surface recombination velocity on the exterior of the pillars. Then, the QE of this structure was evaluated subject to different surface conditions. It was found that alone the surface charge density or surface recombination is detrimental to the QE but that the QE is recovered when both phenomena are present. Subsequently, the crosstalk was analyzed and the superior performance of the PT structure was demonstrated by evaluating the modulation transfer function.     

Excitation of Cy5 in self-assembled lipid bilayers using optical microresonators

Due to their sensitivity and temporal response, optical microresonators are used extensively in the biosensor arena, particularly in the development of label-free diagnostics and measurement of protein kinetics. In the present letter, we investigate using microcavities to probe molecules within biomimetic membranes. Specifically, a method for self-assembling lipid bilayers on spherical microresonators is developed and the bilayer-nature is verified. Subsequently, the microcavity is used to excite a Cy5-conjugated lipid located within the bilayer while the optical performance of the microcavity is characterized. The emission wavelength of the dye and the optical behavior of the microcavity agree with theoretical predictions.     

Corrosion of high temprature alloys in the primary circuit helium of high temperature gas cooled reactors. – Part I: Theoretical background

The interaction of Ni and Fe-Ni base alloys with the reactive impurities H₂O, CO, H₂ and CH₄ in simulated cooling gas of the primary circuit of the High Temperature Gas Cooled Reactor (HTGR) causes corrosion effects that can significantly influence the mechanical properties. Apart from the formation of surface scales (oxides, carbides or mixed oxides/carbides), structural changes of the alloys are observed; depending on gas composition, gas supply rate and test temperature, carburization or decarburization can occur. In this report it is shown that an interpretation of the basic corrosion effects is possible on the basis of a modified stability diagram for chromium provided that - the kinetics of elementary gas metal reactions are incorporated in the expressions for carbon activity and oxygen partial pressure of the atmosphere and - the gradients of the potentials across the surface scales are taken into account. The interpretation allows the derivation of the corrosion behaviour of NiCr-base alloys in different HTGR helium compositions and enables the limits for the formation of protective chromia surface scales to be given. The influence of alloying elements other than chromium can be explained qualitatively. The results can be transferred to other reactive gas mixtures, which are characterized by an oxygen partial pressure near to the dissociation pressure of the scale forming oxides.     

How good is the quality of health care in the United States?

Studies over the past decade show that some people are receiving more care than they need, and some are receiving less. Simple averages from a number of studies indicate that 50 percent of people received recommended preventive care; 70 percent, recommended acute care; 30 percent, contraindicated acute care; 60 percent, recommended chronic care; and 20 percent, contraindicated chronic care. These studies strongly suggest that the care delivered in the United States often does not meet professional standards. Efforts to measure quality and report routinely on the results to the public at large would allow more definitive assessments of the status of the nation's health care and would enable us to single out the areas in need of improvement.     

Digestion of carbohydrate from white beans (Phaseolus vulgaris L.) in healthy humans

An anatomic study of the ligamentous structures of the triangular fibrocartilage complex and their attachments on the ulnar styloid was performed using 27 embalmed cadaver wrists. The dorsal and palmar distal radioulnar ligaments of the triangular fibrocartilage complex in each specimen contained a superficial and a deep portion. The deep portion of both ligaments inserted on the fovea of the ulna. The superficial portion of both ligaments surrounded the articular disc uniting at the ulnar-most portion of the articular disc. The tissue that is between the ulnar aspect of the superficial ligament (and integrated on its periphery) and the ulnar capsule is defined as the meniscus homologue. Anatomic variations in the meniscus homologue and the prestyloid recess (the cavity adjacent to the ulnar styloid) were seen in 1 of 3 ways; the narrow opening type in 74% of specimens, the wide opening type in 11%, and the no opening type in 15%. The ulnotriquetral ligament inserted on the palmar-radial aspect of the base of the ulnar styloid and the ulnolunate ligament inserted on the palmar border of the articular disc.     

The sexual practices of Asian and Pacific Islander high school students

The less common methods of medication administration that used to be used only in the hospital are also now used in alternate settings. Understanding the treatment modalities, care requirements, and complications of these alternate routes of administration is important for nurses who participate in the care of patients receiving infusions. Several alternate routes of administration are discussed, with emphasis on the more commonly used methods: intra-arterial, intraspinal, intraventricular, intraperitoneal, intraosseous, and several other routes.     

Efficacy of novel antimicrobials against clinical isolates of opportunistic amebas

Using atomic force microscopy (AFM), we have investigated neutron-induced DNA double-strand breaks in plasmids in aqueous solution. AFM permits direct measurement of individual DNA molecules with an accuracy of a few nanometers. Furthermore, the analysis of the DNA fragment size distribution is non-parametric, whereas other methods are dependent on the model. Neutron irradiation of DNA results in the generation of many short fragments, an observation not made for damage induced by low-LET radiation. These data provide clear experimental evidence for the existence of clustered DNA double-strand breaks and demonstrate that short DNA fragments may be produced by such radiations in the absence of a nucleosomal DNA structure.     

The integrative hospital explored via acupuncture

The nature of the inhibition of camel retina acetylcholinesterase (AChE) activity by tetrahydro-aminoacridine (THA, tacrine) has been investigated in the present study. The non-significant change of the percent inhibition of AChE by THA with respect to various lengths of the preincubation period showed the type of the reversible inhibition. THA reversibly inhibited AChE activity in a concentration dependent manner; IC50 was 0.23 microM while the IC100 was 14.22 microM. The K(m) for the hydrolysis of acetylthiocholine iodide was found to be 62.6 microM in the control system; a value increased in the THA treated systems. The Vmax was 0.472 mumole/min/mg protein for the control system, while it decreased in the THA treated systems. Dixon, as well as Lineweaver-Burk, plots and their secondary replots indicated that the nature of the inhibition is of the linear mixed type, which is considered to be a partial competitive and pure non-competitive mixture. The values of Ki(slope) and K'i(intercept) were estimated as 0.068 microM and 0.181 microM, respectively. The K'i was greater than Ki indicating that THA has a greater affinity of binding for the peripheral site than the active site of the camel retina AChE. The use of camel retina as a good experimental animal model may open new avenues for studying acetylcholine and AChE metabolism.     

Archaebacterial DNA polymerases tightly bind uracil-containing DNA

We show that archaebacterial DNA polymerases are strongly inhibited by the presence of small amounts of uracil-containing DNA. Inhibition appears to be competitive, with the DNA polymerase exhibiting approximately 6500-fold greater affinity for binding the inhibitor than a DNase I-activated DNA substrate. All six archaebacterial DNA polymerases tested were inhibited, while no eubacterial, eukaryotic, or bacteriophage enzymes showed this effect. Only a small inhibition resulted when uracil was present as the deoxynucleoside triphosphate, dUTP. The rate of DNA synthesis was reduced by approximately 40% when dUTP was used in place of dTTP for archaebacterial DNA polymerases. Furthermore, an incorporated dUMP served as a productive 3'-primer terminus for subsequent elongation. In contrast, the presence of an oligonucleotide containing as little as a single dUrd residue was extremely inhibitory to DNA polymerase activity on other primer-template DNA.