A Digital Gate for Isolating the First and Second Waveforms in Cyclic Voltammetry

ABSTRACT

A circuit for gating the first one or two voltage waveforms passed to an electrochemical cell was designed, built, and tested. The device is independent of the voltage program stage and the potential or current control unit. Signals up to 1 kHz in frequency may be gated to the control amplifier stage and recording device. The voltage waveform can be initiated at any desired potential and in either the positive or negative direction. The response time of the switch is limited only by that of the mechanical relay used. Increased frequency response may easily be realized by replacing the mechanical relay with a FET controlled follower gate. The impedance of the device is essentially nil (0.150 ω) and it can gate any periodic or aperiodic voltage program up to 20 V peak-to-peak. The output current capacity is limited by the relay specifications; the current limit of the device described is 300 mA.     

Human uterine vascular structures in normal and diseased states

Menstrual bleeding disorders are one of the most common problems presenting to the gynaecologist. There is increasing evidence that alterations in human uterine vascular structures are associated with spontaneous and sex steroid-induced changes in menstrual bleeding patterns. This article will discuss the normal anatomy and physiology of uterine vascular growth, breakdown, and repair and will indicate where altered anatomy and function may contribute to menstrual disorder. In particular, impact of low-dose progestogens on the endometrial vasculature and endometrial vascular fragility will be discussed. Disturbances of myometrial vascular growth and remodeling, including fibroids, adenomyosis, implantation, and arterio-venous malformations will also be addressed.     

ω-Assisted nucleation and growth of α precipitates in the Ti–5Al–5Mo–5V–3Cr–0.5Fe β titanium alloy

This paper discusses the structural and compositional changes at the nanometer scale associated with the nucleation and growth of α precipitates in the β titanium alloy Ti-5553 (Ti–5Al–5Mo–5 V–3Cr–0.5Fe) with ω precipitates acting as heterogeneous nucleation sites. The microstructural evolution in this alloy, during β-solutionizing, quenching and aging type heat-treatments, has been investigated by combining results from scanning electron microscopy, orientation imaging microscopy, transmission electron microscopy, high-resolution TEM and three-dimensional atom probe (3DAP) tomography. Athermal ω precipitates form in this alloy on quenching from above the β transus temperature. On isothermal annealing at low temperatures, these ω precipitates coarsen to form chemically ordered ω precipitates, accompanied by the nucleation of the stable α phase. Annealing at higher temperatures leads to dissolution of ω and further growth of α precipitates accompanied by clustering of different α variants in self-accommodating morphologies. 3DAP results indicate that annealing at lower temperatures (～350 °C) leads to initial nucleation of α precipitates with a non-equilibrium composition, nearly identical to that of the β matrix. Subsequent aging at higher temperatures (～600 °C) leads to more pronounced partitioning of alloying elements between the two phases. These results indicate that the structural body-centered cubic to hexagonal close-packed transformation and the compositional partitioning of alloying elements occur in sequential steps, resulting in a mixed-mode displacive-diffusional transformation, similar to the bainite transformation in steels.     

NEW HYBRID METHOD FOR MASS EXCHANGE NETWORK OPTIMIZATION

A new hybrid optimization method is presented that is fairly robust and can be accomplished in an automatic way. The main idea is using integer cuts and bounds, based on driving force plot analysis, for the lean streams to decrease the possibility of being trapped in local optima. A new initial solution is constructed if the MINLP solution is infeasible; otherwise the earlier found best solution is used. In consequence, the MINLP model is modified in the iteration steps. The iteration is stopped when the total annual cost (TAC) in the solution reaches 1.1·TAC_target.     

Copper-Indium Alloy Transformations

Phase transformations of copper-indium alloy thin films are analyzed by hot-stage x-ray diffraction (XRD) over the temperature range from 30 to 425 °C in controlled ambient. Thin films of Cu/In with a molar ratio of approximately 0.9 were used. In situ experiments were carried out in a reducing hydrogen atmosphere to minimize oxide formation. The as-deposited Cu/In alloy transformed at 150 °C to form Cu₁₁In₉. Ramping the temperature to the upper limit of 425 °C revealed an additional transformation at 350 °C to form Cu₁₆In₉. (DuPont Company Contribution Number: 7722).     

From Concordances to Subject Portals: Supportingthe Text-Centred Humanities Community

This paper discusses selected aspects of the work ofthe CTI Centre for Textual Studies, a Centre which hasits roots in a 1984 initiative and ceased to operatein 1999. The work of the Centre was grounded inhumanities computing, a subject area which itself hasdeveloped over time. The article compares earlierobservations made by Joseph Raben and Susan Hockeyabout the integration of resources within humanitiesteaching and learning, to current realities. Its focusis the development of access to distributed resources,beginning with an interface between the early PC andthe mainframe and ending with a vision of a humanitiesportal to distributed resources.     

Epistaxis

Epistaxis is a common clinical problem. The widespread availability of endoscopic equipment is shifting management philosophy toward targeting the bleeding point. This shift may have a significant impact on decreasing length of stay and blood transfusion rates. Advances in interventional radiology have also reduced the risk of embolization. Patient education, especially teaching first-aid measures to patients at high risk for nosebleeds, also encourages more effective use of health care resources.     

A simple wet etch for GaN

A simple UV photo-enhanced wet etch has been developed for GaN. Unlike photoelectrochemical wet etching, this technique does not require an electrical contact to be made to the sample, and nitrides deposited on insulating substrates (such as sapphire) can be etched. The technique relies on adding an appropriate oxidizing agent, in this case, peroxydisulfate to KOH solutions. Maximum etch rates are observed at pH 12.4. The etch rate increases linearly with light intensity at 365 nm up to intensities of 25 mW/cm², where etch rates of up to 50 nm/min are observed.     

Priming of human neutrophils by peroxynitrite: potential role in enhancement of the local inflammatory response

The antimicrobial activity of a new super-oxidized water, Sterilox, has been tested against Mycobacterium tuberculosis, Mycobacterium avium-intracellulare, Mycobacterium chelonae, Escherichia coli (including type O157), Enterococcus faecalis, Pseudomonas aeruginosa, Bacillus subtilis var niger spores, methicillin-resistant Staphylococcus aureus, Candida albicans, poliovirus type 2 and human immunodeficiency virus HIV-1. Under clean conditions, freshly generated Sterilox was found to be highly active against all these micro-organisms giving a 5 log10 (99.999%) or greater reduction in two minutes or less.     

Studying low-density lipoprotein-monoclonal antibody complexes using dynamic laser light scattering and analytical ultracentrifugation

Monoclonal antibody complexes have proven very useful in the study of low-density lipoproteins (LDLs). Thus, complexes composed of two different monoclonal antibodies, selected from a panel of 11 different antibodies, and LDL have been employed to map apolipoprotein B (apoB) on the surface of the LDL. In this way, apoB was found to surround the LDL as a ribbon with a bow [Chatterton, J. E., et al. (1995) J. Lipid Res. 36, 2027-2037]. Moreover, monoclonal MB19, which recognizes a polymorphic site, has been employed to quantitate the two different allelic forms of apoB found on LDL in human sera, and in this way, we assessed the effect of most of the known common polymorphisms of this protein as well as detected the depletion of the normal allele product in two forms of familial defective apoB-100 [Chatterton, J. E., et al. (1995) Biochemistry 34, 9571-9580; Pullinger, C. R., et al. (1995) J. Clin. Invest. 95, 1225-1234]. In this paper, these studies have been extended by examining by dynamic light scattering and sedimentation velocity techniques the complexes formed with only one antibody, and complexes formed using two antibodies. Our data show that the largest complex formed with a single monoclonal antibody was that of an LDL dimer; no larger, nonspecific complexes were present. With two antibodies, a variety of complexes were seen. Thus, monoclonal antibodies MB47 and 4G3, which bound about 55 degrees apart, formed a very stable dimer. Monoclonal antibodies MB47 and 2D8, which bound 136 degrees apart, formed a very stable tetramer, with four LDLs held together in probably a circular structure with four monoclonal antibodies. Finally, monoclonal antibodies 2D8 and 1D1, which bound 86 degrees apart, probably formed a less stable LDL tetramer, held together by three to four monoclonal antibodies. A rationale for these structures is discussed, as well as the biological relevance of these complexes.