Accessing the Two‐Electron Charge Storage Capacity of MnO2 in Mild Aqueous Electrolytes

Rechargeable batteries based on MnO₂ cathodes, able to operate in mild aqueous electrolytes, have attracted attention due to their appealing features for the design of low‐cost stationary energy storage devices. However, the charge/discharge mechanism of MnO₂ in such media is still a matter of debate. Here, an in‐depth quantitative spectroelectrochemical analysis of MnO₂ thin‐films provides a set of unrivaled mechanistic insights. A major finding is that charge storage occurs through the reversible two‐electron faradaic conversion of MnO₂ into Mn²⁺ in the presence of a wide range of weak Brønsted acids, including the [Zn(H₂O)₆]²⁺ or [Mn(H₂O)₆]²⁺ complexes present in aqueous Zn/MnO₂ batteries. Furthermore, it is shown that buffered electrolytes loaded with Mn²⁺ are ideal to achieve highly reversible conversion of MnO₂ with both high gravimetric capacity and remarkably stable charging/discharging potentials. In the most favorable case, a record gravimetric capacity of 450 mA·h·g^?1 is obtained at a high rate of 1.6 A·g^?1, with a Coulombic efficiency close to 100% and a MnO₂ utilization of 84%. Overall, the present results challenge the common view on MnO₂ the charge storage mechanism in mild aqueous electrolytes and underline the benefit of buffered electrolytes for high‐performance rechargeable aqueous batteries.     

The Perinatal Risk Index: Early Risks Experienced by Domestic Adoptees in the United States

We aimed to assess comprehensively the prevalence of perinatal risks experienced by a potentially high-risk yet understudied population of children domestically adopted in the United States. Data are from participant report and medical records from mothers (n = 580) who completed a domestic adoption placement with nonrelatives at or near birth (Mean placement age = 7 days). We describe a comprehensive measure of perinatal risks, including divergences from previous assessment tools and the incorporation of multiple reporters, and report the prevalence of various types of perinatal risks. The prevalence of each specific risk factor was generally low, although several risks were more prevalent in this sample than estimates from nationally representative publicly available data. Nearly the entire sample (99%) experienced some type of risk exposure. Birth mothers who placed their children for adoption domestically in the US experience higher levels of perinatal risks than the national average, but not for all specific types of risk. Thus, the developmental trajectories of children adopted domestically may systematically differ from the general population to the extent that these specific perinatal risks impact development.     

L-arginine inhibits apoptosis via a NO-dependent mechanism in Nb2 lymphoma cells

Prolactin (PRL) inhibits apoptosis and stimulates proliferation of the PRL-dependent rat Nb2 lymphoma cell line by divergent signaling pathways. Nitric oxide (NO) was recently identified as a downstream regulator of PRL action, and as an inhibitor of apoptosis in immune cells. In the present study, the role of NO in PRL-regulated Nb2 cell function was investigated. Nb2 cells expressed the endothelial nitric oxide synthase (eNOS) isoform, whereas neuronal NOS (nNOS) and inducible NOS (iNOS) mRNAs were undetectable. The eNOS mRNA was abundantly expressed in PRL-deprived, growth-arrested cells but decreased by at least 3-fold at 3-24 h following PRL treatment. Downregulation of eNOS was not accompanied by a corresponding decrease in the eNOS protein, the level of which remained constant for at least 24 h after PRL treatment. PRL had no effect on the phosphorylation state or subcellular redistribution of the eNOS enzyme, or on production of NO by Nb2 cells. However, increasing concentrations of L-arginine (NOS substrate) alone increased NO production in these cells and significantly enhanced PRL-stimulated cell proliferation. NO releasers (SNAP, DEA/NO, SIN-1) also significantly enhanced Nb2 cell proliferation in the presence of a submaximal dose of PRL (0.125 ng/ml). In the absence of PRL, the NO releasers alone promoted cell survival and maintained a viable cell density significantly higher than that of untreated PRL-deprived cells. L-arginine or the NO releaser DEA/NO alone significantly inhibited apoptosis in Nb2 cells deprived of PRL for 5 days. Expression of the anti-apoptotic gene bcl-2, which was stimulated within 1 h by PRL, was upregulated by L-arginine or DEA/NO alone at 2 h and 8 h, respectively. These findings suggest that NO produced by eNOS inhibits apoptosis and promotes the survival of growth-arrested Nb2 lymphoma cells via a prolactin-independent, Bcl-2-mediated pathway.     

Hybridization assay at a disposable electrochemical biosensor for the attomole detection of amplified human cytomegalovirus DNA

A disposable electrochemical biosensor for the detection of DNA sequences related to the human cytomegalovirus (HCMV) is described. The sensor relies on the adsorption of an amplified human cytomegalovirus DNA strand onto the sensing surface of a screen-printed carbon electrode, and to its hybridization to a complementary single-stranded biotinylated DNA probe. The extent of hybrids formed was determined with streptavidin conjugated to horseradish peroxidase. The peroxidase label was indirectly quantified by measuring the amount of the chromophore and electroactive product 2,2'-diaminoazobenzene generated from the o-phenylenediamine substrate. The intensity of differential pulse voltammetric peak currents resulting from the reduction of the enzyme-generated product was related to the number of target HCMV-amplified DNA molecules present in the sample, and the results were compared to those obtained with standard methods, i.e., agarose gel electrophoresis quantification and colorimetric hybridization assay in a microtiter plate. A detection limit of 0.6 amol/ml of HCMV-amplified DNA fragment was obtained with the electrochemical DNA biosensor. The electrochemical method was 23,000-fold more sensitive than the gel electrophoresis technique and 83-fold more sensitive than the colorimetric hybridization assay in a microtiter plate.     

HPTN 062: A Pilot Randomized Controlled Trial Exploring the Effect of a Motivational-Interviewing Intervention on Sexual Behavior among Individuals with Acute HIV Infection in Lilongwe,Malawi

Objective

We pilot tested a Motivational Interviewing (MI) –based counseling intervention for individuals with Acute HIV Infection (AHI) to reduce risky sexual behavior in Lilongwe, Malawi.

Methods

Twenty-eight individuals diagnosed with AHI were randomized to receive either brief education alone, or the brief education plus the MI-based intervention, called Uphungu Wanga. Participants in Uphungu Wanga received four sessions delivered on the day of diagnosis, three days later and at weeks 1 and 2 with a booster session at week 8; participants were followed for 24 weeks from diagnosis. An interviewer administered quantitative questionnaire was conducted at baseline and at weeks 2, 4, 8, 12, 16, 20 and 24. Semi-structured qualitative interviews (SSI) were conducted at weeks 2, 8, 12, and 24.

Results

The majority of participants in both arms reported rapid and sustained behavior change following diagnosis with AHI. Very few participants reported having sex without a condom after diagnosis. Participants reported a trend towards fewer sex partners and abstaining from sex during study follow-up. Participants in the MI-based arm provided concrete examples of risk reduction strategies in the SSIs while those in the brief education arm primarily described reducing risk behavior, suggesting that the MI-based group may have acquired more risk reduction skills.

Conclusions

Individuals in both study arms reduced risky sexual behaviors after diagnosis with AHI. We found few major differences between study arms during the 6-month follow up period in self-reported sexual behaviors therefore a MI-based intervention may not be needed to trigger behavior change following AHI. However, comparing the MI-based intervention to repeated brief education sessions made it difficult to assess the potential benefit of an MI-based intervention in a setting where standard counseling often consists of one post-test session. Nevertheless, provision of counseling immediately following diagnosis with HIV to support behavior change should remain a priority.

Trial Registration

ClinicalTrials.gov NCT01197027     

Validity of weight loss to estimate improvement in body composition in individuals attending a wellness center

The accuracy of weight loss in estimating successful changes in body composition (BC), namely fat mass (FM) loss, is not known and was addressed in our study. To assess the correlation between change in body weight and change in FM, fat% and fat‐free mass (FFM), 465 participants (41% male; 41 ± 13 years), who met the criteria for weight change assessment at a wellness center, underwent air‐displacement plethysmography (ADP). Body weight and BC were measured at the same time. We categorized the change in body weight, FM and FFM as an increase if there was >1 kg gain, a decrease if there was >1 kg loss and no change if the difference was ≤1 kg. We estimated the diagnostic performance of weight change to identify improvement in BC. After a median time of 132 days, there was a mean weight change was 2.4 kg. From the 255 people who lost >1 kg of weight, 216 (84.7%) had lost >1 kg of FM, but 69 (27.1%) had lost >1 kg of FFM. Of the 143 people with no weight change, 42 (29.4%) had actually lost >1 kg of FM. Of the 67 who gained >1 kg of weight at follow‐up, in 23 (34.3%) this was due to an increase in FFM but not in FM. Weight change had a NPV of 73%. Our results indicate that favorable improvements in BC may go undetected in almost one‐third of people whose weight remains the same and in one‐third of people who gain weight after attending a wellness center. These results underscore the potential role of BC measurements in people attempting lifestyle changes.     

The Observed Association between Maternal Anxiety and Adolescent Asthma: Children of Twin Design Suggest Familial Effects

Background

Previous studies indicate that maternal anxiety is associated with asthma in the adolescent child, but mechanisms are unclear.

Objective

To investigate the association between maternal anxiety and maternal, self- and register-based report of asthma in the adolescent child, and whether the association remains after control of familial confounding (shared environmental and genetic factors).

Method

From the Twin and Offspring Study of Sweden, 1691 mothers (1058 twins) and their adolescent child were included. The association between maternal self-reported anxiety (Beck Anxiety Inventory (BAI) and Karolinska Scales of Personality (KSP) somatic or psychic anxiety) and asthma based on subjective (maternal or child report) or objective (register-based diagnosis and medication) measures were analysed using logistic regression. The children-of-twins design was used to explore whether genes or environment contribute to the association.

Results

Maternal BAI anxiety (OR 2.02, CI 1.15–3.55) was significantly associated with adolescent asthma reported by the mother. Maternal KSP somatic anxiety (OR 1.74, CI 1.04–2.91) and psychic anxiety (OR 1.74, CI 1.05–2.86) was significantly associated with breathlessness reported by the adolescent child. In contrast, maternal anxiety was not associated with increased risk for the register-based outcomes of asthma diagnosis or medication. The results remained also after adjusting for covariates and the children-of-twins analyses which indicate that the association was due to familial confounding.

Conclusions

We found some associations between maternal anxiety and subjectively reported offspring asthma or breathlessness which may be due to familial effects. A likely candidate for explaining this familial confounding is heritable personality traits associated with both anxiety and subjective measures of asthma.