Background: Biofortification is a strategy to relieve vitamin A (VA) deficiency. Biofortified maize contains enhanced provitamin A concentrations and has been bioefficacious in animal and small human studies.Objective: The study sought to determine changes in total body reserves (TBRs) of vitamin A with consumption of biofortified maize.Design: A randomized, placebo-controlled biofortified maize efficacy trial was conducted in 140 rural Zambian children. The paired 13C-retinol isotope dilution test, a sensitive biomarker for VA status, was used to measure TBRs before and after a 90-d intervention. Treatments were white maize with placebo oil (VA−), orange maize with placebo (orange), and white maize with VA in oil [400 μg retinol activity equivalents (RAEs) in 214 μL daily] (VA+).Results: In total, 133 children completed the trial and were analyzed for TBRs (n = 44 or 45/group). Change in TBR residuals were not normally distributed (P < 0.0001); median changes (95% CI) were as follows: VA−, 13 (−19, 44) μmol; orange, 84 (21, 146) μmol; and VA+, 98 (24, 171) μmol. Nonparametric analysis showed no statistical difference between VA+ and orange (P = 0.34); both were higher than VA− (P = 0.0034). Median (95% CI) calculated liver reserves at baseline were 1.04 (0.97, 1.12) μmol/g liver, with 59% >1 μmol/g, the subtoxicity cutoff; none were <0.1 μmol/g, the deficiency cutoff. The calculated bioconversion factor was 10.4 μg β-carotene equivalents/1 μg retinol by using the middle 3 quintiles of change in TBRs from each group. Serum retinol did not change in response to intervention (P = 0.16) but was reduced with elevated C-reactive protein (P = 0.0029) and α-1-acid glycoprotein (P = 0.0023) at baseline.Conclusions: β-Carotene from maize was efficacious when consumed as a staple food in this population and could avoid the potential for hypervitaminosis A that was observed with the use of preformed VA from supplementation and fortification. Use of more sensitive methods other than serum retinol alone, such as isotope dilution, is required to accurately assess VA status, evaluate interventions, and investigate the interaction of VA status and infection. This trial was registered at clinicaltrials.gov as NCT01814891.

Hippocrates, a philosopher who lived from 460 to 359 BC is often quoted as saying, "Let your food be thy medicine and your medicine be thy food." Having lived just shy of a century at a time when life expectancies were much less, he must have understood the importance of a healthy diet. A diet high in fruit and vegetables has been linked to optimal health in a variety of studies. One vegetable that has gained popularity is the carrot due in part to the introduction of "cut & peel" convenience packages. Although most people in the United States know carrots as an orange vegetable that can be eaten raw or in a variety of cooked dishes, original carrots were yellow and purple. These carrot varieties are currently undergoing phenotypic recurrent selection to improve the profile of compounds considered to be beneficial. This process is called biofortification, which has increased provitamin A content by >40% since 1970. The most novel carrot produced to date is an orange-purple-red variety that not only contains provitamin A activity as ␣-and ␤-carotene, but also contains anthocyanins and the nonprovitamin A carotenoid lycopene, of which both are potent antioxidants. A functional food is one that provides benefit beyond basic nutrition. Biofortified carrots of many colors not only provide vitamin A, but may contribute to optimal health. Because supplements have not been shown to be overly beneficial, except for correcting deficiencies, whole foodbased approaches to enhance health by utilizing functional foods such as biofortified carrots should be considered.

The giant piezoresistance (PZR) previously reported in silicon nanowires is experimentally investigated in a large number of depleted silicon nano- and microstructures. The resistance is shown to vary strongly with time due to electron and hole trapping at the sample surfaces independent of the applied stress. Importantly, this time-varying resistance manifests itself as an apparent giant PZR identical to that reported elsewhere. By modulating the applied stress in time, the true PZR of the structures is found to be comparable with that of bulk silicon.

a b s t r a c tThe use of polymers in the context of flexible systems such as flexible sensors leads to an incompatibility issue: on the one hand, the flexibility of the polymer must not be to the detriment of the fabrication process, e.g. excessive thermal expansion leading to process failure and on the other hand, certain applications will require high flexibility and also a specific mechanical stiffness, e.g. artificial skin, smart clothes, flexible screen. In other words, a compromise is necessary between rigidy for processing and controlled flexibility for applications. In this context it is crutial to be able to tune the mechanical properties of such polymers. Polydimethylsiloxane (PDMS) is a very versatile and useful soft polymeric material -Elastic modulus typically ≈1 MPa. This paper investigates the stiffness tunability of PDMS by varying the hardening agent to PDMS base ratio over 19:1 to 2:1, and using two extreme curing processes, i.e. 120 min at 100 • C and 2 days at 165 • C. It was observed that the stiffness of PDMS can be accurately controlled from 800 kPa to 10 MPa with a rupture limit higher than 20%. To our knowledge this is the highest reported elastic modulus in PDMS by combining mixing ratio and curing temperature. The impact of such a stiffness variation on potential functional properties such as the rupture limit, Poisson's ratio and material's wetting contact angle is also analysed. We observe that the wetting contact angle depends on the bulk mechanical properties of the PDMS. The observations will be of use to all technological communities who are engaged in using PDMS-type polymers for their specific applications.