Hydrogen Evolution by Polymer Photocatalysts; a Possible Photocatalytic Cycle

We propose, supported by ab-initio calculations, a possible photocatalytic cycle for hydrogen evolution by a prototypical polymer photocatalyst, poly(p-phenylene), in the presence of a sacrificial electron donor. As part of that cycle we also introduce a family of related sites on the polymer that in the absence of a noble metal co-catalyst can facilitate the evolution of molecular hydrogen when the polymer is illuminated. The bottlenecks for hydrogen evolution, electron transfer from the sacrificial electron donor and hydrogen-hydrogen bond formation, are discussed, as well as how they could potentially be improved by tuning the polymer properties and how they change in the presence of a noble-metal co-catalyst

Epigenetics, Nutrition, and Infant Health

The field of epigenetics is currently garnering a great deal of interest, exploring how our very molecular makeup in the form of modifications to the genome can be altered by factors as diverse as aging, disease, nutrition, stress, alcohol, and exposure to pollutants. Epigenetic changes have previously been implicated in the etiology of a variety of diseases, notably in the development of certain cancers, and inherited growth disorder syndromes, but the exploration of epigenetics’ role in fetal programming is still in its infancy. This chapter focuses on how nutritional exposures during pregnancy may affect the infant epigenome, and the impact that such modifications may have on the long-term health of the child. We start by describing some keys concepts in epigenetics and discuss windows of epigenetic plasticity in the context of the developmental origins of health and disease (DOHaD) hypothesis. We then review some of the key mechanisms by which nutrition can affect the epigenome, with a particular focus on the role of one-carbon metabolism. We finish by outlining some of the child health outcomes that have been linked to epigenetic dysregulation, and discuss possible next steps that need to be realized if insights into the basic science of epigenetics are to be translated into tangible public health benefits

Breaking the color-reddening degeneracy in type Ia supernovae

A new method to study the intrinsic color and luminosity of type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis (PCA) on spectral series SNe Ia between -12.5 and +17.5 days from B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of color excess due to dust-extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic color variability. Such metric space is a good predictor of the epoch when the maximum in the B-V color curve is reached. Multivariate Partial Least Square (PLS) regression predicts the intrinsic B band light-curve and the intrinsic B-V color curve up to a month after maximum. This allows to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host-galaxy of SNe Ia is found, on average, to be consistent with typical Milky-Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with large sample publicly available. Future automated surveys as LSST will provide a large number of light curves. The analysis shows that observing accompaning spectra for a significative number of SNe will be important even in the case of "normal" SNe Ia.Comment: 11 pages, 11 figure

Commentary: Challenging public health orthodoxies—prophesy or heresy?†

In 1633, after many years of skirmishing with the Catholic Church over his support for Copernicus’ heliocentric theory of the universe, Galileo was finally sentenced by the inquisition to prison and religious penances. In a formal ceremony at the church of Santa Maria Sofia Minerva, he was forced to abjure his errors, and spent the rest of his life under house arrest in Sienna. The prophet had been convicted as a heretic. Without, yet, wishing to confer the status of prophet on Peter Aaby and his disciples based in Guinea Bissau, there are significant parallels in their persistent challenges to some of the deepest rooted public health orthodoxies of the present day. Aaby has a long history of interrogating datasets in a way that others hav

Maternal perception of malnutrition among infants using verbal and pictorial methods in Kenya.

OBJECTIVE: To compare mothers' perceptions of their own infants' nutritional status with anthropometric indicators of undernutrition. DESIGN: A qualitative study and cross-sectional quantitative survey. The qualitative study involved developing tools to assess mother's perception. Two methods of verbal description and a pictorial scale were developed. The quantitative survey involved measuring maternal perception and comparing it with the anthropometric measures of weight-for-age Z-score (WAZ) and mid-upper arm circumference-for-age Z-score (MUACZ). SETTING: A rural community setting in Kenya. SUBJECTS: Seventy-four infants aged between 4 and 6 months, and their mothers, living in rural Kenya were enrolled. RESULTS: Using verbal description, the positive and negative likelihood ratios were 3.57 (95 % CI 1.44, 9.98) and 0.69 (95 % CI 0.50, 0.96) respectively for MUACZ<-2; and 4.60 (95 % CI 1.60, 13.3) and 0.67 (95 % CI 0.49, 0.92) respectively for WAZ<-2. Using the pictorial scale, the positive and negative likelihood ratios were 8.30 (95 % CI 1.91, 36.3) and 0.69 (95 % CI 0.52, 0.93) respectively for MUACZ<-2; and 4.31 (95 % CI 1.22, 15.0) and 0.78 (95 % CI 0.61, 1.00) respectively for WAZ<-2. CONCLUSIONS: In a rural community, mothers better identify undernutrition in their infants using a pictorial scale than verbal description. However, neither can replace formal anthropometric assessment. Objective anthropometric tools should be validated for identification of severe acute malnutrition among infants aged less than 6 months

Transient expression of ß-glucuronidase in recalcitrant Ugandan sweetpotato and putative transformation with two cry genes.

Sweetpotato (Ipomoea batatas Lam.) has high potential to contain hunger, malnutrition and poverty in sub-Saharan Africa (SSA), since it gives early yield with few inputs. However, productivity of the crop in Africa is very low due to various challenges, such as severe viral diseases and increasing attacks by sweetpotato weevils, Cylas puncticollis and C. brunneus. Effective resistance to weevils has not been identified in the sweetpotato gene pool. On the other hand, the weevil-resistance genes, cry7Aa1 and cry3Ca1 were assembled into a plasmid vector for use in genetic transformation of African sweetpotato cultivars. The parameters for efficient transfer of these genes and the conditions for de novo regeneration optimised in preliminary studies were used in the genetic transformation of Ugandan landrace ‘Kyebandula’ with Agrobacterium tumefaciens EHA 105 harbouring the plasmid pCIP84, which contains cry7Aa1, cry3Ca1 and nptII in its T-DNA. Fifty-four percent of the explants formed adventitious buds. With a mean of 7 buds formed per explant, 6.0% explants formed shoots with a mean of one shoot per explant for those explants that formed shoots on medium containing 50 mg L-1 kanamycin as a selection agent. PCR analysis using primers for cry7Aa1 showed that the transformation efficiency could be as high as 2%. These data highlight the potential of genetic transformation in transferring resistance genes and pave way for enhancement of food security through production of adapted sweetpotato weevil resistant cultivars.Key Words: Agrobacterium tumefaciens, b-glucuronidase, Ipomoea batata