Abundance, composition, and vertical transport of PAHs in marsh sediments

Petroleum-derived hydrocarbons continue to persist in Wild Harbor, West Falmouth, MA, following a spill of No. 2 fuel oil in 1969 from the barge Florida. Recent analysis of marsh sediments revealed that residues of degraded oil are present with concentrations of total petroleum hydrocarbons as high as approximately 9 mg g(-1). Polycyclic aromatic hydrocarbons (PAHs) constitute only a minor fraction of these residues with maximum concentrations of 134 mirog g(-1), but their fate is of interest because of their potential toxicity to organisms. As compared to typical unweathered No. 2 fuel oil, the current distribution of PAHs in the sediments reflects substantial weathering by abiotic and biotic processes, specifically a preferential loss of naphthalenes relative to phenanthrenes, as well as isomer-specific biodegradation of alkylated PAHs. Based on comparison to results from an earlier study, it appears that little or no change has occurred to the distribution of PAHs since 1989, indicating that weathering at this site has stalled or is now proceeding at a significantly slower rate. To assess whether sediment-water partitioning and molecular diffusion in the interstitial medium are now the dominant processes controlling the vertical distribution of PAHs, downcore profiles were compared to a numerical model. While in some cases the model accurately reproduced the measured data, there were instances where the distribution of PAHs was slightly under or overestimated. Reasons for these discrepancies are discussed and are likely due to bioturbation, colloid-facilitated transport, or both. Assessment of the influence of these processes on the spilled oil expands our understanding of the overall fate of these compounds and their potential long-term effects on the environment.     

A Micro-Flow-Batch Analyzer Using an In-line Cadmium Sponge Microcolumn for the Photometric Determination of Nitrate and Nitrite in Dairy Samples

In this study, a micro-flow-batch analyzer (μFBA) using an in-line cadmium reduction microcolumn for the photometric determination of nitrate and nitrite in dairy samples is described. The method is based on the Griess-Llosvay reaction and measuring of the absorbance at 540 nm using a green LED integrated into the μFBA built in the urethane-acrylate resin. Initially, the nitrite content of the dairy sample is analyzed in the mixing chamber, while the nitrate is reduced to nitrite in cadmium sponge microcolumn coupled to the microsystem. Nitrate content was calculated from the difference between nitrate plus nitrite (expressed as nitrite) and nitrite content. The analytical curve for nitrate and nitrite was linear in the work range of 10.0–100.0 μg L^?1 with a correlation coefficient of 0.992 and 0.998, respectively. The limit of detection and relative standard deviation were estimated at 0.39 μg L^?1 and <1.7 % (n?=?5) for nitrite and 0.41 μg L^?1 and <1.3 % (n?=?5) for nitrate. Comparing with the reference methods, no statistically significant differences were observed when applying the paired t test at a 95 % confidence level. The accuracy was assessed through recovery test (97.7 to 102.9 %). The proposed microsystem-employed in-line cadmium sponge microcolumn presented satisfactory portability, robustness, flexibility, low-cost device, and reduced chemicals consumption compared to recent methods. Thus, μFBA is potentially useful as an alternative for other automatic determinations using in-line pretreatment steps.     

Bioactivities from marine algae of the genus gracilaria

Seaweeds are an important source of bioactive metabolites for the pharmaceutical industry in drug development. Many of these compounds are used to treat diseases like cancer, acquired immune-deficiency syndrome (AIDS), inflammation, pain, arthritis, as well as viral, bacterial, and fungal infections. This paper offers a survey of the literature for Gracilaria algae extracts with biological activity, and identifies avenues for future research. Nineteen species of this genus that were tested for antibacterial, antiviral, antifungal, antihypertensive, cytotoxic, spermicidal, embriotoxic, and anti-inflammatory activities are cited from the 121 references consulted.     

Morphological and molecular pathology of CCL4‐induced hepatic fibrosis in connexin43‐deficient mice

Gap junction channels, formed by connexins (Cx), are involved in the maintenance of tissue homeostasis, cell growth, differentiation, and development. Several studies have shown that Cx43 is involved in the control of wound healing in dermal tissue. However, it remains unknown whether Cx43 plays a role in the control of liver fibrogenesis. Our study investigated the roles of Cx43 heterologous deletion on carbon tetrachloride (CCl₄)‐induced hepatic fibrosis in mice. We administered CCl₄ to both Cx43‐deficient (Cx43^+/?) and wild‐type mice and examined hepatocellular injury and collagen deposition by histological and ultrastructural analyses. Serum biochemical analysis was performed to quantify liver injury. Hepatocyte proliferation was analyzed immunohistochemically. Protein and messenger RNA (mRNA) expression of liver connexins were evaluated using immunohistochemistry as well as immunoblotting analysis and quantitative real‐time PCR. We demonstrated that Cx43^+/? mice developed excessive liver fibrosis compared with wild‐type mice after CCl₄‐induced chronic hepatic injury, with thick and irregular collagen fibers. Histopathological evaluation showed that Cx43^+/? mice present less necroinflammatory lesions in liver parenchyma and consequent reduction of serum aminotransferase activity. Hepatocyte cell proliferation was reduced in Cx43^+/? mice. There was no difference in Cx32 and Cx26 protein or mRNA expression in fibrotic mice. Protein expression of Cx43 increased in CCl₄‐treated mice, although with aberrant protein location on cytoplasm of perisinusoidal cells. Our results demonstrate that Cx43 plays an important role in the control and regulation of hepatic fibrogenesis. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Functional Test of Mesh-Based NoCs with Deterministic Routing: Integrating the Test of Interconnects and Routers

In this work, a comprehensive functional-based test method is presented to integrate the test of Network-on-Chip interconnects and routers. Experimental results show that fault coverage can reach up to 100% of interconnect faults and over 90% of router faults. The test structures needed to implement the test method are presented and the scalability of the method is discussed. We show that our approach scales well with the number of routers and channel width. The cost of the functional test strategy and the cost of a scan-based strategy are also analyzed in order to present scenarios where each strategy fits better.     

Reproductive performance of grazing dairy cows following presynchronization and resynchronization protocols

Objectives were to compare the effect of presynchronization and resynchronization methods on fertility responses of grazing dairy cows at first and second artificial insemination (AI) and pregnancy rate during the entire breeding season. Lactating dairy cows (n = 1,263) in 2 seasonal grazing farms were blocked, within farm, by parity, breed and days in milk. Within each block, cows were randomly assigned to 1 of 4 treatments arranged as a 2 × 2 factorial with 2 presynchronization and 2 resynchronization treatments. Cows had their estrous cycles presynchronized with either a PGF_2α-based program (Presynch) consisting of 2 injections of PGF_2α administered 14 d apart and starting the timed AI protocol 11 d later, or with a PGF_2α-GnRH-based presynchronization program (G6G) consisting of an injection of PGF_2α, followed 3 d later by an injection of GnRH and starting the timed AI protocol 6 d later. All cows received the first insemination on the same day, which was considered study d 0 and also d 0 of the breeding season. All cows received the 5-d timed AI protocol that consisted of GnRH on d −8, PGF_2α on d −3 and −2, and GnRH + timed AI on d 0. Blood was sampled and analyzed for progesterone on d −8. On d 12, cows in each presynchronization treatment either remained as untreated controls (RCON) or received a controlled internal drug-release (CIDR) insert containing progesterone for 7 d (RCIDR). Estrus was observed daily starting on d 19 and cows in estrus were inseminated on the same day. On d 35, bulls were placed with the cows for an additional 65 d, completing a 100-d breeding season. Holstein cows were less likely to have progesterone ≥1 ng/mL on d −8, and had less expression of estrus and pregnancy per AI (P/AI), which resulted in a slower rate of pregnancy and a smaller proportion of pregnancy at the end of the study than did Jersey or crossbred cows. In addition, body condition, days in milk, and plasma progesterone concentration at the first GnRH injection of the timed AI protocol had marked effects on the reproductive performance of lactating grazing dairy cows. A greater proportion of G6G cows had progesterone ≥1ng/mL at the first GnRH injection of the timed AI protocol compared with Presynch cows (82.0 vs. 74.3%). Presynchronization treatment did not influence P/AI, but cows in G6G had increased risk of pregnancy loss between d 30 and 65 after the first AI (12.9 vs. 8.1%). Nevertheless, an interaction between presynchronization and ovarian status was observed, and cows initiating the timed AI with progesterone ≥1 ng/mL had greater P/AI when previously treated with Presynch than G6G. On the other hand, G6G benefited P/AI of cows initiating the timed AI with progesterone <1 ng/mL. Resynchronization with RCIDR altered the pattern of return to estrus, but it did not increase the rate of re-insemination and decreased the proportion of pregnant cows at the end of the 100-d breeding period (80.6 vs. 84.4%).     

Quality of mango nectar processed by high-pressure homogenization with optimized heat treatment

This work aimed to evaluate the effect of high-pressure homogenization (HPH) with heat shock on Aspergillus niger, vitamin C, and color of mango nectar. The nectar was processed at 200 MPa followed by heat shock, which was optimized by response surface methodology by using mango nectar ratio (45 to 70), heat time (10 to 20), and temperature (60 to 85 °C) as variables. The color of mango nectar and vitamin C retention were evaluated at the optimized treatments, that is, 200 MPa + 61.5 °C/20 min or 73.5 °C/10 min. The mathematical model indicates that heat shock time and temperature showed a positive effect in the mould inactivation, whereas increasing ratio resulted in a protective effect on A. niger. The optimized treatments did not increase the retention of vitamin C, but had positive effect for the nectar color, in particular for samples treated at 200 MPa + 61.5 °C/20 min. PRACTICAL APPLICATION: The results obtained in this study show that the conidia can be inactivated by applying HPH with heat shock, particularly to apply HPH as an option to pasteurize fruit nectar for industries.     

Experimental photophysical characterization of fluorophores in the vicinity of gold nanoparticles

We propose an experimental-based tool for dealing with fluorescence modulation close to nanoparticles for application in studies of fluorophores in the vicinity of gold nanoparticles (AuNPs), typically addressed via theoretical models. We performed a photophysical characterization of fluorophores in the vicinity of AuNPs, showing that correct Φ(F) determination suffers from a local pH effect, and address the observed radiative enhancement. Our approach is based on the experimental assurance that the reference fluorophores are in the same optical conditions as those of the AuNP-fluorophore conjugates. We demonstrate the relevance for introducing corrections for the inner filter effect and the reabsorption of the emitted light caused by AuNPs. The proposed approach could circumvent the need for theoretical based corrections and allow for more accurate determination of fluorescence emission in the vicinity of gold nanoparticles.     

Spatial carrier distribution in InP/GaAs type II quantum dots and quantum posts

We performed a detailed investigation of the structural and optical properties of multi-layers of InP/GaAs quantum dots, which present a type II interface arrangement. Transmission electronic microscopy analysis has revealed relatively large dots that coalesce forming so-called quantum posts when the GaAs layer between the InP layers is thin. We observed that the structural properties and morphology affect the resulting radiative lifetime of the carriers in our systems. The carrier lifetimes are relatively long, as expected for type II systems, as compared to those observed for single layer InP/GaAs quantum dots. The interface intermixing effect has been pointed out as a limiting factor for obtaining an effective spatial separation of electrons and holes in the case of single layer InP/GaAs quantum-dot samples. In the present case this effect seems to be less critical due to the particular carrier wavefunction distribution along the structures.