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1.  Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors 
Nanoscale Research Letters  2014;9(1):517.
This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm2/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm2/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing.
PMCID: PMC4178550  PMID: 25276107
Zinc oxide nanowire; Top-down fabrication; Field-effect transistor; Atomic layer deposition
2.  Economic Benefits of Hepatitis B Vaccination at Sexually Transmitted Disease Clinics in the U.S. 
Public Health Reports  2008;123(4):504-513.
This study assessed the long-term economic implications of a national program to vaccinate all adults treated at sexually transmitted disease (STD) clinics in a single year.
A model was developed to track the long-term disease outcomes and costs among a hypothetical cohort of 2 million STD clinic clients accessing services in one year, using data from published sources and demonstration projects at STD clinics in San Diego (California), Illinois, and Denver (Colorado). The model estimated net economic benefits of a routine hepatitis B vaccination policy at STD clinics nationwide compared with no vaccination.
Without a vaccination program, an estimated 237,021 new hepatitis B virus (HBV) infections would occur over the lifetimes of the 2 million STD clinic clients seen in a single year. HBV-related medical costs and productivity losses would be $1.6 billion. In a national program for routine vaccination at STD clinics, 1.3 million adults would be expected to receive at least one vaccine dose, and an estimated 45% of the new HBV infections expected without vaccination would be prevented. The vaccination program would cost $138 million, HBV infections occurring despite the program would cost $878 million, and clients' time and travel would cost $45 million. The net economic benefit (savings) of routine vaccination would be $526 million. If the indirect costs of lost productivity due to HBV infection are not considered, routine vaccination would have a net cost of $28 million.
Estimates from this model suggest a national program for routine hepatitis B vaccination of adults at STD clinics would be a cost saving to society.
PMCID: PMC2430647  PMID: 18763413
3.  Low Prevalence of Hepatitis C Virus Antibody in Men Who Have Sex with Men Who Do Not Inject Drugs 
Public Health Reports  2007;122(Suppl 2):63-67.
It is well documented that injection drug users (IDUs) have a high prevalence of antibodies to hepatitis C virus (HCV). Sexual transmission of HCV can occur, but studies have shown that men who have sex with men (MSM) without a history of injection drug use are not at increased risk for infection. Still, some health-care providers believe that all MSM should be routinely tested for HCV infection. To better understand the potential role of MSM in risk for HCV infection, we compared the prevalence of antibody to HCV (anti-HCV) in non-IDU MSM with that among other non-IDU n at sexually transmitted disease (STD) clinics and human immunodeficiency virus (HIV) counseling and testing sites in three cities.
During 1999–2003, public health STD clinics or HIV testing programs in Seattle, San Diego, and New York City offered counseling and testing for anti-HCV for varying periods to all clients. Sera were tested using enzyme immunoassays, and final results reported using either the signal-to-cutoff ratio or recombinant immunoblot assay results. Age, sex, and risk information were collected. Prevalence ratios and 95% confidence intervals were calculated.
Anti-HCV prevalence among IDUs (men and women) was between 47% and 57% at each site, with an overall prevalence of 51% (451/887). Of 1,699 non-IDU MSM, 26 (1.5%) tested anti-HCV positive, compared with 126 (3.6%) of 3,455 other non-IDU men (prevalence ratio 0.42, 95% confidence interval 0.28, 0.64).
The low prevalence of anti-HCV among non-IDU MSM in urban public health clinics does not support routine HCV testing of all MSM.
PMCID: PMC1831798  PMID: 17542456
4.  Medical Care and Alcohol Use after Testing Hepatitis C Antibody Positive at STD Clinic and HIV Test Site Screening Programs 
Public Health Reports  2007;122(1):37-43.
The Centers for Disease Control and Prevention recommend screening individuals at risk for hepatitis C virus (HCV) infection. However, few published data describe outcomes of individuals with antibody to HCV (anti-HCV) identified through screening programs. The purpose of this study was to assess rates of medical evaluation and HCV treatment, change in alcohol consumption, and barriers to medical care after testing anti-HCV positive through a public screening program.
Anti-HCV positive individuals identified through San Diego sexually transmitted disease (STD) clinics and an HIV test site screening program were informed of positive test results, provided education and referral, and contacted by telephone three, six, and ≥12 months later.
From September 1, 1999, to December 31, 2001, 411 anti-HCV positive individuals were newly identified, of whom 286 (70%) could be contacted ≥ three months after receipt of test results (median length [range] of follow-up 14 [3–35] months). Of these 286, 156 (55%) reported having received a medical evaluation, of whom 19 (12%) began HCV treatment. Of 132 who reported drinking alcohol before diagnosis, 100 (76%) reported drinking less after diagnosis. Individuals with medical insurance at diagnosis were more likely than those without insurance to obtain a medical evaluation during follow-up (75 [68%] of 111 vs. 70 [45%] of 155; p<0.001). Among those who did not obtain an evaluation, the most commonly reported reason was lack of insurance.
Only about half of newly identified anti-HCV positive individuals received a medical evaluation, although 76% reported drinking less alcohol. Identifying ways to improve medical access for those who are anti-HCV positive could improve the effectiveness of screening programs.
PMCID: PMC1802122  PMID: 17236606
5.  The Molecular Basis for Na-Dependent Phosphate Transport in Human Erythrocytes and K562 Cells 
The Journal of General Physiology  2000;116(3):363-378.
The kinetics of sodium-stimulated phosphate flux and phosphate-stimulated sodium flux in human red cells have been previously described (Shoemaker, D.G., C.A. Bender, and R.B. Gunn. 1988. J. Gen. Physiol. 92:449–474). However, despite the identification of multiple isoforms in three gene families (Timmer, R.T., and R.B. Gunn. 1998. Am. J. Physiol. Cell Physiol. 274:C757–C769), the molecular basis for the sodium-phosphate cotransporter in erythrocytes is unknown. Most cells express multiple isoforms, thus disallowing explication of isoform-specific kinetics and function. We have found that erythrocyte membranes express one dominant isoform, hBNP-1, to which the kinetics can thus be ascribed. In addition, because the erythrocyte Na-PO4 cotransporter can also mediate Li-PO4 cotransport, it has been suggested that this transporter functions as the erythrocyte Na–Li exchanger whose activity is systematically altered in patients with bipolar disease and patients with essential hypertension. To determine the molecular basis for the sodium-phosphate cotransporter, we reasoned that if the kinetics of phosphate transport in a nucleated erythroid-like cell paralleled those of the Na-activated pathway in anucleated erythrocytes and yet were distinct from those known for other Na-PO4 cotransporters, then the expressed genes may be the same in both cell types. In this study, we show that the kinetics of sodium phosphate cotransport were similar in anuclear human erythrocytes and K562 cells, a human erythroleukemic cell line. Although the erythrocyte fluxes were 750-fold smaller, the half-activation concentrations for phosphate and sodium and the relative cation specificities for activation of 32PO4 influx were similar. Na-activation curves for both cell types showed cooperativity consistent with the reported stoichiometry of more than one Na cotransported per PO4. In K562 cells, external lithium activation of phosphate influx was also cooperative. Inhibition by arsenate, KI = 2.6–2.7 mM, and relative inhibition by amiloride, amiloride analogs, phosphonoformate, and phloretin were similar. These characteristics were different from those reported for hNaPi-3 and hPiT-1 in other systems. PCR analysis of sodium-phosphate cotransporter isoforms in K562 cells demonstrated the presence of mRNAs for hPiT-1, hPiT-2, and hBNP-1. The mRNAs for hNaPi-10 and hNaPi-3, the other two known isoforms, were absent. Western analysis of erythrocytes and K562 cells with isoform-specific antibodies detected the presence of only hBNP-1, an isoform expressed in brain neurons and glia. The similarities in the kinetics and the expression of only hBNP-1 protein in the two cell types is strong evidence that hBNP-1 is the erythrocyte and K562 cell sodium-phosphate cotransporter.
PMCID: PMC2233690  PMID: 10962014
cotransport; phosphate; sodium; lithium; BNP-1
6.  Characteristics of Chloride Transport in Human Red Blood Cells 
The Journal of General Physiology  1973;61(2):185-206.
The efflux of chloride-36 from human erythrocytes under steady-state conditions is a saturable process that is competitively inhibited by bicarbonate and noncompetitively inhibited by acetate. This chloride self-exchange flux is reversibly dependent on the pH of the medium between 5.7 and 9.6 with a maximum flux at pH 7.8. The increase in chloride flux between pH 5.7 and 7.8 is inexplicable by the fixed charge hypothesis. The interpretations are made that chloride transport in human erythrocytes is carrier mediated, that bicarbonate utilizes the same transport mechanism, and that the mechanism can be titrated with hydrogen ions into less functional forms for chloride transport.
PMCID: PMC2203467  PMID: 4688320
7.  Potassium permeability in β-thalassemia minor red blood cells 
Journal of Clinical Investigation  1972;51(5):1043-1050.
The intracellular content of K+ in thalassemia minor red blood cells is markedly reduced after incubation in autologous serum for 24 hr at 37°C. There is no compensatory increase in intracellular Na+ concentration of the cell thus reduced. This change is due to an acquired increase in selective permeability of the membrane to K+. This phenomenon follows the depletion of energy sources in the thalassemia minor cells but does not follow comparable depletion in normal cells. The loss of osmotically active intracellular contents probably accounts for the increased resistance of incubated thalassemia minor red blood cells to osmotic lysis.
PMCID: PMC292232  PMID: 4553518
8.  The Effect of 2,4,6-Trinitro-m-Cresol on Cation and Anion Transport in Sheep Red Blood Cells 
The Journal of General Physiology  1971;57(5):593-609.
2,4,6-Trinitro-3-methyl-phenol (trinitrocresol, H+TNC-) was found to inhibit anion and stimulate cation movements across the membranes of both high potassium (HK) and low potassium (LK) sheep red blood cells. The concentration of TNC- required to inhibit SO4- and Cl- efflux (10-5-10-3 M) was less than that required to increase Na+ and K+ leakage (10-3-10-2 M). Both the inhibition of anion and stimulation of cation permeation were reversed if TNC- was washed from the red cells. The cation leak caused by TNC- was much greater at 0° and 37°C than at room temperature (23°C). In sheep red cells, TNC- was found to be about 20 times more effective than salicylate and about 40 times more effective than thiocyanate in increasing cation leak. TNC- also inhibited the ouabain-sensitive potassium influx.
PMCID: PMC2203116  PMID: 5553103
9.  Influence of hemoglobin precipitation on erythrocyte metabolism in alpha and beta thalassemia 
Certain aspects of the metabolism of centrifuged young and old erythrocytes in hemoglobin H disease have been examined and compared with similar studies of beta thalassemia and normal cells. Glycolysis, hexose monophosphate shunt activity (HMPS), potassium flux, and glutathione (GSH) content were measured. The distributions of hemoglobins H and F, as well as the activities of erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and glutamic oxalacetic transaminase (GOT), were utilized for estimations of the relative ages of the cell samples. The young erythrocytes in hemoglobin H disease differed in several respects from older hemoglobin H cells. They contained more soluble hemoglobin H and GSH and, after splenectomy, fewer inclusions. HMPS activity was subnormal in hemoglobin H young cells and rose to normal activity in old cells. Potassium flux tended to increase in old cells when inclusions were present.
Beta thalassemia young cells contained less hemoglobin F and, after splenectomy, more inclusions than old cells. In addition, they had markedly increased glycolysis and HMPS activity. GSH was randomly distributed. Potassium flux was increased in younger cells and particularly increased when inclusions appeared in younger cells after splenectomy.
The results are interpreted to indicate that inclusion formation is associated with increased erythrocyte cation permeability in the thalassemia syndromes. This is not related to the level of intracellular GSH.
The decreased HMPS activity in young hemoglobin H cells may be due to the presence of the extra thiols of soluble hemoglobin H which can act as a reducing agent. The substitution of hemoglobin H for glutathione in this capacity would then spare the NADPH-requiring glutathione reductase system. As a consequence, HMPS activity would decline. However, in older cells the oxidized hemoglobin H precipitates; these must rely upon GSH and glutathione reductase activity for thiol reduction capacity. Accordingly, HMPS activity increases to normal in the old cell population.
PMCID: PMC322189  PMID: 5765025

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