Dielectric and Raman Spectroscopic Studies of Na0.5Bi0.5TiO3–BaSnO3 Ferroelectric System

A series of lead‐free perovskite solid solutions of (1 ? x) Na_0.5Bi_0.5TiO₃(NBT)—x BaSnO₃(BSN), for 0.0 ≤ x ≤ 0.15 have been synthesized using a high‐temperature solid‐state reaction route. The phase transition behaviors are studied using dielectric and Raman spectroscopic techniques. The ferroelectric to relaxor phase transition temperature (T_FR) and the temperature corresponding to maximum dielectric permittivity (T_m) are estimated from the temperature‐dependent dielectric data. Dielectric studies show diffuse phase transition around ~335°C in pure NBT and this transition temperature decreases with increase in x. The disappearance of x‐dependence of A₁ mode frequency at ~134 cm^?1 for x ≥ 0.1 is consistent with rhombohedral‐orthorhombic transition. In situ temperature dependence Raman spectroscopic studies show disappearance and discontinuous changes in the phonon mode frequencies across rhombohedral (x < 0.1)/orthorhombic (x ≥ 0.1) to tetragonal transition.     

Association with natural organic matter enhances the sunlight-mediated inactivation of MS2 coliphage by singlet oxygen

MS2 coliphage, a surrogate for human enteric viruses, is inactivated by singlet oxygen (1O2) produced via sunlight-mediated excitation of natural organic matter (NOM) in surface waters. The 1O2 concentration within a NOM macromolecule or supramolecular assembly ([1O2]internal) is orders of magnitude higher than in the bulk solution ([1O2]bulk). In close proximity of NOM, MS2 is thus exposed to an elevated 1O2 concentration ([1O2]NOM), and inactivation is likely to be enhanced as compared to the bulk solution. In experiments using a solar simulator, we determined [1O2]bulk, [1O2]internal, as well as the association of MS2 with four NOMs (Fluka humic acid, FHA; Suwannee river humic acid, SRHA; Aldrich humic acid, AHA; Pony lake fulvic acid, PLFA), and studied their effect on the MS2 inactivation rate constant, k(obs), over a range of 1-25 mg NOM/L. The k(obs) values were modeled as the sum of the inactivation rate constants in close proximity to the NOM and in the bulk solution, assuming Langmuir-type adsorption of NOM onto MS2. FHA and SRHA exhibited 13-22 fold greater adsorption equilibrium constants than AHA and PLFA. Inactivation in the bulk solution contributed between 2% (20 mg/L FHA) and 39% (5 mg/L AHA) toward the overall k(obs). Thus, even for the less adsorbing NOM, inactivation was dominated by [1O2]NOM rather than [1O2]bulk. Changes in solution chemistry to promote closer interactions between MS2 and NOM also enhanced k(obs). Addition of Mg2+ to neutralize the negative surface charge of MS2 and NOM increased k(obs) up to 4.1-fold. Similarly, lowering the solution pH closer to the isoelectric point of MS2 (pl = 3.9) enhanced k(ob), 51-fold in 5 mg/L AHA.     

Environmental stresses and skeletal deformities in fish from the Willamette River, Oregon

The Willamette River, one of 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of the Willamette River detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (Newberg pool [NP], rivermile [RM] 26 - 55) and middle (Wheatland Ferry [WF], RM 72 - 74) river, relative to those in the upper river (Corvallis [CV], RM 125-138). The objective of this study was to determine the likely cause of these skeletal deformities. In 2002 and 2003, deformity loads in Willamette River fishes were 2-3 times greater at the NP and WF locations than at the CV location. There were some differences in water quality parameters between the NP and CV sites, but they did not readily explain the difference in deformity loads. Concentrations of bioavailable metals were below detection limits (0.6 - 1 microg/ L). Concentrations of bioavailable polychlorinated biphenyls (PCBs) and chlorinated pesticides were generally below 0.25 ng/L. Concentrations of bioavailable polycyclic aromatic hydrocarbons were generally less than 5 ng/L. Concentrations of most persistent organic pollutants were below detection limits in ovary/oocyte tissue samples and sediments, and those that were detected were not significantly different among sites. Bioassay of Willamette River water extracts provided no evidence that unidentified compounds or the complex mixture of compounds present in the extracts could induce skeletal deformities in cyprinid fish. However, metacercariae of a digenean trematode were directly associated with a large percentage of deformities detected in two Willamette River fishes, and similar deformities were reproduced in laboratoryfathead minnows exposed to cercariae extracted from Willamette River snails. Thus, the weight of evidence suggests that parasitic infection, not chemical contaminants, was the primary cause of skeletal deformities observed in Willamette River fish.     

Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) beads for heavy metal removal

Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) [poly(EGDMA-VIM)] hydrogel (average diameter 150-200 microm) was prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with n-vinyl imidazole (VIM). The copolymer hydrogel bead composition was characterized by elemental analysis and found to contain 5 EGDMA monomer units each VIM monomer unit. Poly(EGDMA-VIM) beads had a specific surface area of 59.8 m2/g. Poly(EGDMA-VIM) beads were characterized by swelling studies and scanning electron microscopy (SEM). These poly(EGDMA-VIM) beads with a swelling ratio of 78% were used for the heavy metal removal studies. Chelation capacity of the beads for the selected metal ions, i.e., Cd(II), Hg(II) and Pb(II) were investigated in aqueous media containing different amounts of these ions (10-750 mg/l) and at different pH values (3.0-7.0). Chelation rate was very fast. The maximum chelation capacities of the poly(EGDMA-VIM) beads were 69.4 mg/g for Cd(II), 114.8 mg/g for Pb(II) and 163.5 mg/g for Hg(II). The affinity order on molar basis was observed as follows: Hg(II) > Cd(II) > Pb(II). Chelation behavior of heavy metal ions could be modelled using both the Langmuir and Freundlich isotherms. pH significantly affected the chelation capacity of VIM incorporated beads. Chelation of heavy metal ions from synthetic wastewater was also studied. The chelation capacities are 45.6 mg/g for Cd(II), 74.2 mg/g for Hg(II) and 92.5 mg/g for Pb(II) at 0.5 mmol/l initial metal concentration. Regeneration of the chelating-beads was easily performed with 0.1 M HNO3. These features make poly(EGDMA-VIM) beads potential candidate adsorbent for heavy metal removal.     

Enrichment of eggs in n-3 polyunsaturated fatty acids by feeding hens with different amount of linseed oil in diet

The production of n-3 polyunsaturated fatty acid enriched eggs by addition of linseed oil to the laying hens' diet has been evaluated in terms of production parameters and n-6/n-3 ratio. A total of 150 18weeks old Lohmann Brown laying hens were housed in cages and fed with basal diet and four experimental diets containing 1%, 2%, 3% or 4% of linseed oil added to the basal diet. The effect of the altered level of linseed oil on hens laying performance, fatty acid content and composition and cholesterol content in egg yolk has been evaluated during 13weeks of experiment. Egg weight, yolk fat content, yolk weight, yolk percentage and shape index were not influenced by dietary treatment. The ratio between n-6 and n-3 polyunsaturated fatty acids in eggs decreased in first 5weeks and then remained stable until the end of the experiment for all experimental groups. Different contents of linseed oil in feed highly influenced the n-6/n-3 ratio (P<0.0001). Addition of linseed oil did not influence the cholesterol content in yolks (P=0.5200) while the only factor affecting the cholesterol content was the hens age (P<0.0001).     

Making sanitation count: developing and testing a device for assessing latrine use in low-income settings

While efforts are underway to expand latrine coverage to an estimated 2.6 billion people who lack access to improved sanitation, there is evidence that actual use of latrines is suboptimal, limiting the potential health and environmental gains from containment of human excreta. We developed a passive latrine use monitor (PLUM) and compared its ability to measure latrine activity with structured observation. Each PLUM consisted of a passive infrared motion detector, microcontroller, data storage card, and batteries mounted in a small plastic housing that was positioned inside the latrine. During a field trial in Orissa, India, with ～115 households, the number of latrine events measured by the PLUMs was in good agreement with that measured by trained observers during 5 h of structured observation per device per week. A significant finding was that the presence of a human observer was associated with a statistically significant increase in the number of latrine events, i.e., the users modified their behavior in response to the observer. Another advantage of the PLUM was the ability to measure activity continuously for an entire week. A shortcoming of the PLUM was the inability to separate latrine events that occurred in immediate succession, leading to possible undercounting during high-traffic periods. The PLUM is a promising technology that can provide detailed measures of latrine use to improve the understanding of sanitation behaviors and how to modify them and for assessing the intended health, livelihood, and environmental benefits of improved sanitation.     

Why Sugar Is Added to Food: Food Science 101

Avoiding too much sugar is an accepted dietary guidance throughout the world. The U.S. Nutrition Facts panel includes information on total sugars in foods. A focus on added sugars is linked to the concept of discretionary calories and decreasing consumption of added sugars or free sugars as a means to assist a consumer to identify foods that are nutrient‐dense. On March 14, 2014, the U.S. Food and Drug Administration proposed that including “added sugars” declaration on the Nutrition Facts panel would be another tool to help consumers reduce excessive discretionary calorie intake from added sugars. Through deductive reasoning, labeling added sugars is one tactic to potentially curb the obesity epidemic in the United States. This review discusses the functions of sugar in food and shows that the methods used to replace added sugars in foods can result in no reduction in calorie content or improvement in nutrient density. Without clear benefit to the consumer for added sugars labeling, this review highlights the complex business obstacles, costs, and consumer confusion resulting from the proposed rule.     

The influence of heat treatment of chickpea seeds on antioxidant and fibroblast growth‐stimulating activity of peptide fractions obtained from proteins digested under simulated gastrointestinal conditions

This study presents the effect of heat treatment of chickpea seeds on biological activity of peptides obtained by in vitro gastrointestinal digestion. The most significant antiradical activity against ABTS^+? expressed as IC₅₀ value was observed for 3.5‐ to 7‐kDa peptide fraction from TC hydrolysate (41.01 μg mL^?1). In turn, peptide fraction of 3.5–7.0 kDa obtained from raw chickpea seeds hydrolysate showed the highest antiradical activity against DPPH^? and Fe²⁺ chelating activity with IC₅₀ value of 20.94 and 52.53 μg mL^?1, respectively. The highest Cu²⁺ chelating activity was observed for peptides obtained from TC hydrolysate (IC₅₀ = 56.60 μg mL^?1). Peptide fraction <3.5 kDa from TC hydrolysate demonstrated the most significant reducing power (0.362 A₇₀₀/μg mL^?1). The peptide fraction of 3.5–7 kDa from TC hydrolysate also showed the highest fibroblast growth‐stimulating activity. These results indicated that the heat treatment process has no significant effect on antiradical activity against DPPH^? and Fe²⁺ chelating ability of peptides.