Understanding Triplet Formation Pathways in Bulk Heterojunction Polymer:Fullerene Photovoltaic Devices

Triplet exciton (TE) formation pathways are systematically investigated in prototype bulk heterojunction (BHJ) “super yellow” poly(p‐phenylene vinylene) (SY‐PPV) solar cell devices with varying fullerene compositions using complementary optoelectrical and electrically detected magnetic resonance (EDMR) spectroscopies. It is shown that EDMR spectroscopy allows the unambiguous demonstration of fullerene triplet production in BHJ polymer:fullerene solar cells. EDMR triplet detection under selective photoexcitation of each blend component and of the interfacial charge transfer (CT) state reveals that low lying fullerene TEs are produced by direct intersystem crossing from singlet excitons (SEs). The direct CT‐TE recombination pathway, although energetically feasible, is kinetically suppressed in these devices. However, high energy CT states in the CT manifold can contribute to the population of the fullerene triplet state via a direct CT‐SE conversion. This undesirable energetic alignment could be one of the causes for the severe reduction in photocurrent observed when the open‐circuit voltage of polymer:fullerene solar cells is pushed to 1.0 V or beyond.     

A concise preparation of the fluorescent amino acid l-(7-hydroxycoumarin-4-yl) ethylglycine and extension of its utility in solid phase peptide synthesis

Incorporation of the unnatural amino acid l-(7-hydroxycoumarin-4-yl)ethylglycine (7-HC) is a powerful and reliable approach for the preparation of fluorescently labeled proteins. The growing popularity of this valuable amino acid prompted us to pursue an improved protocol for its synthetic preparation. The optimized procedure here described provides ready access to multi-gram quantities of 7-HC. Also reported is an extension of the utility of 7-HC in the generation of a protected building block suitable for use in solid phase peptide synthesis. The building block was successfully incorporated at various positions in a series of model peptides, including analogues of the cell penetrating HIV-Tat peptide, further illustrating the utility of this unique amino acid.     

Differences in Overweight and Obesity among Children from Migrant and Native Origin: The Role of Physical Activity,Dietary Intake,and Sleep Duration

A cross-sectional survey was performed to examine to what degree differences in overweight and obesity between native Dutch and migrant primary school children could be explained by differences in physical activity, dietary intake, and sleep duration among these children. Subjects (n=1943) were primary school children around the age of 8–9 years old and their primary caregivers: native Dutch children (n=1546), Turkish children (n=93), Moroccan children (n=66), other non-western children (n=105), and other western children (n=133). Multivariate regressions and logistic regressions were used to examine the relationship between migrant status, child’s behavior, and BMI or prevalence of overweight, including obesity (logistic). Main explanatory variables were physical activity, dietary intake, and sleep duration. We controlled for age, sex, parental educational level, and parental BMI. Although sleep duration, dietary intake of fruit, and dietary intake of energy-dense snacks were associated with BMI, ethnic differences in sleep duration and dietary intake did not have a large impact on ethnic differences in overweight and obesity among children from migrant and native origin. It is suggested that future preventive strategies to reduce overweight and obesity, in general, consider the role of sleep duration. Also, cross-cultural variation in preparation of food among specific migrant groups, focusing on fat, sugar, and salt, deserves more attention. In order to examine which other variables may clarify ethnic differences in overweight and obesity, future research is needed.     

Transmission of Novel Influenza A(H1N1) in Households with Post-Exposure Antiviral Prophylaxis

Background

Despite impressive advances in our understanding of the biology of novel influenza A(H1N1) virus, little is as yet known about its transmission efficiency in close contact places such as households, schools, and workplaces. These are widely believed to be key in supporting propagating spread, and it is therefore of importance to assess the transmission levels of the virus in such settings.

Methodology/Principal Findings

We estimate the transmissibility of novel influenza A(H1N1) in 47 households in the Netherlands using stochastic epidemic models. All households contained a laboratory confirmed index case, and antiviral drugs (oseltamivir) were given to both the index case and other households members within 24 hours after detection of the index case. Among the 109 household contacts there were 9 secondary infections in 7 households. The overall estimated secondary attack rate is low (0.075, 95%CI: 0.037–0.13). There is statistical evidence indicating that older persons are less susceptible to infection than younger persons (relative susceptibility of older persons: 0.11, 95%CI: 0.024–0.43. Notably, the secondary attack rate from an older to a younger person is 0.35 (95%CI: 0.14–0.61) when using an age classification of ≤12 versus >12 years, and 0.28 (95%CI: 0.12–0.50) when using an age classification of ≤18 versus >18 years.

Conclusions/Significance

Our results indicate that the overall household transmission levels of novel influenza A(H1N1) in antiviral-treated households were low in the early stage of the epidemic. The relatively high rate of adult-to-child transmission indicates that control measures focused on this transmission route will be most effective in minimizing the total number of infections.     

Inactivation of Caliciviruses

The viruses most commonly associated with food- and waterborne outbreaks of gastroenteritis are the noroviruses. The lack of a culture method for noroviruses warrants the use of cultivable model viruses to gain more insight on their transmission routes and inactivation methods. We studied the inactivation of the reported enteric canine calicivirus no. 48 (CaCV) and the respiratory feline calicivirus F9 (FeCV) and correlated inactivation to reduction in PCR units of FeCV, CaCV, and a norovirus. Inactivation of suspended viruses was temperature and time dependent in the range from 0 to 100°C. UV-B radiation from 0 to 150 mJ/cm² caused dose-dependent inactivation, with a 3 D (D = 1 log₁₀) reduction in infectivity at 34 mJ/cm² for both viruses. Inactivation by 70% ethanol was inefficient, with only 3 D reduction after 30 min. Sodium hypochlorite solutions were only effective at >300 ppm. FeCV showed a higher stability at pH <3 and pH >7 than CaCV. For all treatments, detection of viral RNA underestimated the reduction in viral infectivity. Norovirus was never more sensitive than the animal caliciviruses and profoundly more resistant to low and high pH. Overall, both animal viruses showed similar inactivation profiles when exposed to heat or UV-B radiation or when incubated in ethanol or hypochlorite. The low stability of CaCV at low pH suggests that this is not a typical enteric (calici-) virus. The incomplete inactivation by ethanol and the high hypochlorite concentration needed for sufficient virus inactivation point to a concern for decontamination of fomites and surfaces contaminated with noroviruses and virus-safe water.     

Sheltering Behavior and Locomotor Activity in 11 Genetically Diverse Common Inbred Mouse Strains Using Home-Cage Monitoring

Functional genetic analyses in mice rely on efficient and in-depth characterization of the behavioral spectrum. Automated home-cage observation can provide a systematic and efficient screening method to detect unexplored, novel behavioral phenotypes. Here, we analyzed high-throughput automated home-cage data using existing and novel concepts, to detect a plethora of genetic differences in spontaneous behavior in a panel of commonly used inbred strains (129S1/SvImJ, A/J, C3H/HeJ, C57BL/6J, BALB/cJ, DBA/2J, NOD/LtJ, FVB/NJ, WSB/EiJ, PWK/PhJ and CAST/EiJ). Continuous video-tracking observations of sheltering behavior and locomotor activity were segmented into distinguishable behavioral elements, and studied at different time scales, yielding a set of 115 behavioral parameters of which 105 showed highly significant strain differences. This set of 115 parameters was highly dimensional; principal component analysis identified 26 orthogonal components with eigenvalues above one. Especially novel parameters of sheltering behavior and parameters describing aspects of motion of the mouse in the home-cage showed high genetic effect sizes. Multi-day habituation curves and patterns of behavior surrounding dark/light phase transitions showed striking strain differences, albeit with lower genetic effect sizes. This spontaneous home-cage behavior study demonstrates high dimensionality, with a strong genetic contribution to specific sets of behavioral measures. Importantly, spontaneous home-cage behavior analysis detects genetic effects that cannot be studied in conventional behavioral tests, showing that the inclusion of a few days of undisturbed, labor extensive home-cage assessment may greatly aid gene function analyses and drug target discovery.     

Temporary Treatment during Primary HIV Infection Does Not Affect Virologic Response to Subsequent Long-Term Treatment

Temporary cART during primary HIV-infection (PHI) did not select for drug resistance mutations after treatment interruption and did not affect the subsequent virological response to long-term cART. Our data demonstrate that fear of drug resistance development is not a valid argument to refrain from temporary early treatment during PHI.     

A feasibility test to estimate the duration of phytoextraction of heavy metals from polluted soils

The practical applicability of heavy metal (HM) phytoextraction depends heavily on its duration. Phytoextraction duration is the main cost factorfor phytoextraction, both referring to recurring economic costs during phytoextraction and to the cost of the soil having no economic value during phytoextraction. An experiment is described here, which is meant as a preliminary feasibility test before starting a phytoextraction scheme in practice, to obtain a more realistic estimate of the phytoextraction duration of a specific HM-polluted soil. In the experiment, HM-polluted soil is mixed at different ratios with unpolluted soil of comparable composition to mimic the gradual decrease of the HM content in the target HM-polluted soil during phytoextraction. After equilibrating the soil mixtures, one cropping cycle is carried out with the plant species of interest. At harvest, the adsorbed HM contents in the soil and the HM contents in the plant shoots are determined. The adsorbed HM contents in the soil are then related to the HM contents in the plant shoots by a log-log linear relationship that can then be used to estimate the phytoextraction duration of a specific HM-polluted soil. This article describes and evaluates the merits of such a feasibility experiment. Potential drawbacks regarding the accuracy of the described approach are discussed and a greenhouse-field extrapolation procedure is proposed.     

Syndromic Approach to Arboviral Diagnostics for Global Travelers as a Basis for Infectious Disease Surveillance

BackgroundArboviruses have overlapping geographical distributions and can cause symptoms that coincide with more common infections. Therefore, arbovirus infections are often neglected by travel diagnostics. Here, we assessed the potential of syndrome-based approaches for diagnosis and surveillance of neglected arboviral diseases in returning travelers.MethodTo map the patients high at risk of missed clinical arboviral infections we compared the quantity of all arboviral diagnostic requests by physicians in the Netherlands, from 2009 through 2013, with a literature-based assessment of the travelers’ likely exposure to an arbovirus.Results2153 patients, with travel and clinical history were evaluated. The diagnostic assay for dengue virus (DENV) was the most commonly requested (86%). Of travelers returning from Southeast Asia with symptoms compatible with chikungunya virus (CHIKV), only 55% were tested. For travelers in Europe, arbovirus diagnostics were rarely requested. Over all, diagnostics for most arboviruses were requested only on severe clinical presentation.ConclusionTravel destination and syndrome were used inconsistently for triage of diagnostics, likely resulting in vast under-diagnosis of arboviral infections of public health significance. This study shows the need for more awareness among physicians and standardization of syndromic diagnostic algorithms.