Thermal and Mechanical Investigation of Interlaminate Glass/Curaua Hybrid Polymer Composites

The combination of synthetic and vegetable fibers in a polyester matrix can produce a hybrid material that may substitute pure glass composites depending on the application. Analysis of their dynamical mechanical properties is important, enabling a better understanding of the structure/property relationship. In this context, various curaua (C) /glass (G) interlaminar hybrid composites were hot compress molded with an overall fiber loading of 30 vol.% and a volume ratio of 1:1 with the aim of studying the influence of the fiber stacking sequence on their thermal, mechanical, and dynamic mechanical properties. Higher hardness was observed when glass fiber was near the surface being tested, and the presence of two consecutive glass layers yielded competitive impact properties in comparison with pure glass composite. In the dynamic mechanical analysis, highest storage modulus values were obtained for the pure glass composite, followed by [G₂/C₂]_s, whereas pure curaua yielded the lowest values. Higher dissipation energy was also found for the [G₂/C₂]_s composite, attributed to the four curaua layers grouped near the mid-plane. The higher glass transition temperature and the largest tan delta peak height and peak width at half-height was found for the pure glass composite.     

A safety study of oral xanthohumol administration and its influence on fertility in Sprague Dawley rats

Xanthohumol (XN) is a prenylated chalcone, which has been shown to possess a broad range of potential cancer preventive and additional biological activities. In the present study, we have determined the subchronic 4-wk toxicity of XN and monitored its influence on fertility and development of offspring in two fertility studies. Four-week-old female Sprague Dawley (SD) rats were treated with 0.5% XN in the diet or with 1,000 mg XN/kg body weight (b.w.) per day by gavage for 28 days. No remarkable treatment-related changes in general appearance and b.w. occurred during the study. After autopsy, liver, kidney, lung, heart, stomach, and spleen were examined macroscopically and histopathologically. Relative liver weights of animals in both treatment groups were significantly reduced by 30--40% in comparison with the control group, indicating weak hepatotoxicity. Also, mammary glands of treated rats appeared less developed compared to the controls. Consequently, we investigated the influence of XN on rat reproduction. In two fertility studies, XN (100 mg/kg b.w. per day), given either for 4 wk prior to or during mating, gestation, and nursing, did not cause any adverse effects on female reproduction and the development of offspring. Noteworthy, treatment of male rats prior to mating significantly (p=0.027) increased the sex ratio of male to female offspring. Overall, lifelong treatment at a daily dose of 100 mg/kg b.w. in a two-generation study did not affect the development of SD rats.     

Stability of Trans‐Resveratrol Encapsulated in a Protein Matrix Produced Using Spray Drying to UV Light Stress and Simulated Gastro‐Intestinal Digestion

Trans‐resveratrol has demonstrated the potential to provide both therapeutic and preventive activities against chronic diseases such as heart disease and cancer. The incorporation of trans‐resveratrol into food products would allow for broader access of this bioactive compound to a larger population. However, this strategy is limited by instability of trans‐resveratrol under environmental conditions and within the digestive system leading to isomerization of trans‐resveratrol (bioactive form) to cis‐resveratrol (bio‐inactive form). Studies in the stabilization of trans‐resveratrol into protein microparticles are presented. Trans‐resveratrol was encapsulated using whey protein concentrate (WPC) or sodium caseinate (SC), with or without anhydrous milk fat (AMF). Binding of resveratrol and aromatic residues in protein was estimated utilizing the Stern–Volmer equation and the number of tryptophan residues. The stability of encapsulated resveratrol was evaluated after exposure to ultraviolet A (UVA) light and 3‐stage in vitro digestion. After UVA light exposure, SC‐based microcapsules maintained a higher trans:cis resveratrol ratio (0.63, P < 0.05) than WPC‐based microcapsules (0.43) and unencapsulated resveratrol (0.49). In addition, encapsulation of resveratrol in both protein microparticles led to an increased digestive stability and bioaccessibility in comparison to unencapsulated resveratrol (47% and 23%, respectively, P < 0.05). SC‐based microcapsules provided a higher digestive stability and bioaccessibility (86% and 81%; P < 0.05) compared to WPC‐based microcapsules (71% and 68%). The addition of AMF to the microcapsules did not significantly change the in vitro digestion values. In conclusion, SC‐based microencapsulation increased the stability of trans‐resveratrol to UVA light exposure and simulated digestion conditions. This encapsulation‐system‐approach can be extended to other labile, bioactive polyphenols.     

Fetuin-A: A negative acute-phase protein linked to adipose tissue function in periparturient dairy cows

Fetuin-A (FetA) is a free fatty acid transporter and an acute-phase protein that enhances cellular lipid uptake and lipogenesis. In nonruminants, FetA is involved in lipid-induced inflammation. Despite FetA importance in lipid metabolism and inflammation, its expression and dynamics in adipose tissue (AT) of dairy cows are unknown. The objectives of this study were to (1) determine serum and AT FetA dynamics over the periparturient period and in mid-lactation cows in negative energy balance (NEB) after a feed restriction protocol and (2) characterize how an inflammatory challenge affects adipocyte FetA expression. Blood and subcutaneous AT were collected from 16 cows with high (≥3.75, n = 8) or moderate (≤3.5, n = 8) body condition score (BCS) at ?26 ± 7 d (far off) and ?8 ± 5 d (close up) before calving and at 10 ± 2 d after parturition (early lactation) and from 14 nonpregnant mid-lactation cows (>220 d in milk) after a feed restriction protocol. Serum FetA concentrations were 0.89 ± 0.13 mg/mL at far off, 0.96 ± 0.13 mg/mL at close up, and 0.77 ± 0.13 mg/mL at early lactation and were 1.09 ± 0.09 and 1.17 ± 0.09 mg/mL in feed-restricted and control cows, respectively. Serum and AT FetA contents decreased at the onset of lactation when lipolysis was higher. No changes in AT and serum FetA were observed after feed restriction induced NEB in mid-lactation cows. Prepartum BCS had no effect on serum FetA, but AT expression of AHSG, the gene encoding FetA, was reduced in periparturient cows with high BCS at dry-off throughout all time points. Circulating FetA was positively associated with serum albumin and calcium and with BCS variation over the periparturient period. The dynamics of AHSG expression were analogous to the patterns of lipogenic markers ABDH5, ELOVL6, FABP4, FASN, PPARγ, and SCD1. Expression of AHSG and FetA protein in AT was inversely correlated with AT proinflammatory markers CD68, CD44, SPP1, and CCL2. In vitro, bovine adipocytes challenged with lipopolysaccharide downregulated FetA protein expression. Adipocytes treated with FetA had lower CCL2 expression compared with those exposed to lipopolysaccharide. Overall, FetA is a systemic and local AT negative acute-phase protein linked to AT function in periparturient cows. Furthermore, FetA may support physiological adaptations to NEB in periparturient cows.     

Quantification of Catechin and Epicatechin in Foods by Enzymatic-Spectrophotometric Method with Tyrosinase

Catechin and epicatechin are important phenolic compounds found mainly in tea leaves, cocoa beans, and in the peels and seeds of fruits. The reliable detection of these compounds by spectrophotometry is limited by the interference with substances that absorb light at similar wavelengths; thus, an effective alternative is to detect the oxidation products of these compounds at more specific wavelengths. This study aimed to develop an analytical method to quantify total catechin and epicatechin in some food samples (cocoa beans, guarana powder, apples, and tea leaves) by enzymatic oxidation with tyrosinase. The samples were extracted in an ultrasonic bath and the purified extracts were oxidized with tyrosinase solution. The quinones formed in the reaction were detected by spectrophotometry. The method was selective and presented linearity between 1.21 and 7.26 mg g^?1, limit of detection of 0.48 mg g^?1, and limit of quantification of 1.61 mg g^?1. The accuracy of the proposed method was reasonable, with recoveries between 84.3 and 90.7% in the fortified matrices. High precision was observed, with low coefficients of variation for repeatability (3.17 to 3.68%) and intermediate precision (3.27%). In cocoa beans, the total catechin and epicatechin level was 1.65 mg g^?1 (3.58 mg g^?1). The successful application of the method was also demonstrated in guarana powder. Therefore, the method can be applicable for spectrophotometric analysis of catechin and epicatechin in samples containing above 1.61 mg g^?1 of these compounds.     

Fetuin-A modulates lipid mobilization in bovine adipose tissue by enhancing lipogenic activity of adipocytes

Fetuin-A (FetA) is an adipokine and free fatty acid (FFA) carrier linked to adipose tissue (AT) function in monogastrics and ruminants. In dairy cows, plasma and AT FetA decrease after parturition, coinciding with reduced lipogenesis and increased lipolysis. In monogastrics, FetA enhances lipogenesis, but its role on lipid mobilization of ruminants is unclear. We hypothesized that FetA modulates lipid mobilization in bovine AT by enhancing the lipogenic activity of adipocytes. Our objective was to determine the effects of FetA on lipogenesis and lipolysis in cultured primary adipocytes from dairy cows. Preadipocytes from the tailhead subcutaneous AT depot were induced to differentiate in a 7-d coculture in vitro model. The effects of FetA on lipolytic responses of adipocytes were evaluated after a 2-h β-adrenergic stimulation with 1 µM isoproterenol (ISO) alone or combined with 0.1 mg/mL of FetA (FetA+ISO), and in cells treated with medium alone (CON) or with 0.1 mg/mL of FetA (FetA). Lipogenic responses of adipocytes treated with CON or FetA from d 5 to 7 of differentiation were assessed by fatty acid (FA) uptake quantification and triacylglycerol (TAG) accumulation, and the gene and protein expression of lipogenic markers. Bovine adipocytes abundantly expressed FetA gene and protein and secreted 48 ± 3.5 ng/DNA relative fluorescence units (RFU). Adrenergic stimulation with ISO increased lipolysis compared with CON, as reflected in the release of glycerol (0.12 ± 0.04 vs. 0.04 ± 0.02 nM/DNA RFU) and FFA (15 ± 13 vs. 6.2 ± 2.4 nM/DNA RFU). Lipolysis induced by ISO was attenuated by the addition of FetA (FetA+ISO) as reflected by lower glycerol (0.06 ± 0.04 nM/DNA RFU) and FFA (5.7 ± 2.7 nM/DNA RFU) release compared with ISO alone. Compared with CON, FetA enhanced lipogenic responses as demonstrated by higher FA uptake and increased accumulation of TAG. Exposure to FetA upregulated 1-acylglycerol-3-phosphate acyltransferase-2 (AGPAT2) gene expression and protein content, as well as its activity. Adipocytes exposed to FetA increased the secretion of the metabolite of AGPAT2, phosphatidic acid. In conclusion, FetA attenuates lipolytic responses and enhances lipogenesis in bovine adipocytes. The upregulation of the rate-limiting lipogenic enzyme AGPAT2 by FetA suggests a potential pathway by which this adipokine promotes TAG synthesis in adipocytes. These findings suggest that FetA is a potential target for lipid mobilization modulation in AT of dairy cows.     

Arsenic speciation in white wine by LC–ICP–MS

This study deals with As speciation in white wine. Arsenic species were selectively determined by liquid chromatography–inductively coupled plasma–mass spectrometry (LC–ICP–MS). Separation of As species was performed using an anion exchange column with ammonium phosphate solution (pH 6.00) as mobile phase. Samples of 14 white wine produced in South America were analysed. They were 10-fold diluted in the mobile phase prior to analysis by LC–ICP–MS. Accuracy was evaluated by recovery tests, whereas As species recovery ranged from 95% to 106%. Additionally, the sum of arsenic species concentration found by LC–ICP–MS was in agreement with the total arsenic concentration determined by ICP–MS after sample digestion. Arsenic species detected were arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMA). As(III) and As(V) were detected in all analysed wine samples and DMA was detected only in wines produced in Argentina. Results for As determination in samples were from 2.9 to 10.3, 8.6 to 17.8, and <0.45 to 1.07 μg L⁻¹ for As(III), As(V) and DMA, respectively.     

Nickel-alumina washcoating on monoliths for the partial oxidation of ethanol to hydrogen production

Preparation of nickel-alumina washcoating on a honeycomb monolith for the ethanol partial oxidation taking at very low residence time was presented. The catalyst presented good dispersion of γ-Al₂O₃ and NiO over the cordierite surface and could be efficient to the ethanol dehydrogenation reaction at low temperatures, as well as it is suitable to intensify hydrogen production due to its good activity for reforming reaction at higher temperatures. As temperature increased, all ethanol was converted by decomposition and this catalyst showed good ability to promote the water-gas shift reaction. The hydrated ethanol increased the ethanol conversion and H₂ production. The high CO₂/CO molar ratio suggested that the water-gas shift inverse reaction equilibrium was achieved. The NiO/Al₂O₃/cordierite was run during few days presenting a large amount of carbon deposition. The FEG-SEM images are in agreement with DTA/TG and Raman results indicating the presence of well-defined filamentous carbon structures.     

Fractionation of polyphenol-enriched apple juice extracts to identify constituents with cancer chemopreventive potential

Apples and apple juices are widely consumed and rich sources of phytochemicals. The aim of the present study was to determine which apple constituents contribute to potential chemopreventive activities, using a bioactivity-directed approach. A polyphenol-enriched apple juice extract was fractionated by various techniques. Extract and fractions were tested in a series of test systems indicative of cancer preventive potential. These test systems measured antioxidant effects, modulation of carcinogen metabolism, anti-inflammatory and antihormonal activities, and antiproliferative potential. Regression analyses indicated that 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging potential correlated with the sum of low molecular weight (LMW) antioxidants (including chlorogenic acid, flavan-3-ols, and flavonols) and procyanidins, whereas peroxyl radicals were more effectively scavenged by LMW compounds than by procyanidins. Quercetin aglycone was identified as a potent Cyp1A inhibitor, whereas phloretin and (-)-epicatechin were the most potent cyclooxygenase 1 (Cox-1) inhibitors. Aromatase and Cyp1A inhibitory potential and cytotoxicity toward HCT116 colon cancer cells increased with increasing content in procyanidins. Overall, apple juice constituents belonging to different structural classes have distinct profiles of biological activity in these in vitro test systems. Since carcinogenesis is a complex process, combination of compounds with complementary activities may lead to enhanced preventive effects.     

Compromises between form and function in grid-connected,building-integrated photovoltaics (BIPV) at low-latitude sites

The integration of photovoltaic (PV) modules on building façades and rooftops is an ideal application of solar electricity generators in the urban environment. Maximum annual performance of grid-connected PV is usually obtained with modules tilted at an angle equal to the site latitude, facing the equator. The performance of PV systems not tilted and oriented ideally can drop considerably, depending on site latitude. With grid parity – when the cost of solar electricity becomes competitive with conventional electricity – expected in many countries in the present decade, a more widespread application of PV on buildings is expected, and in this context the main goal of this paper is to demonstrate that good compromises between form and function are possible. In this work we compare the annual energy generation of a curved BIPV system installed as a car port rooftop, with an ideally-oriented and tilted, flat BIPV system installed as a building’s rooftop cover at a low-latitude site (27°S). For the one-year period analysed, the curved-shape BIPV system annual yield was 12% lower than that of the reference BIPV system, and during the summer months (November to February), the curved BIPV installation presented a higher energy yield than the latitude-tilted generator. With these results we show that a good compromise can be reached between form and function in BIPV systems.