Health & Environmental Research Online (HERO)


1,2-Dibromo-3-chloropropane


1,956 References Were Found:

Journal Article
Journal Article

Doubly Balanced Connected Graph Partitioning

Authors: Soltan, S; Yannakakis, M; Zussman, Gil; ACM (2017) HERO ID: 4822548

[Less] We introduce and study the Doubly Balanced Connected graph Partitioning (DBCP) problem: Let G=(V, E) . . . [More] We introduce and study the Doubly Balanced Connected graph Partitioning (DBCP) problem: Let G=(V, E) be a connected graph with a weight (supply/demand) function p:V ->{-1, +1} satisfying p(V)=Sigma(j is an element of v) p(j)=0. The objective is to partition G into (V-1, V-2) such that G[V-1] and G[V-2] are connected, vertical bar P(V-1)vertical bar, vertical bar P(V-2)vertical bar <= c(p), and max{vertical bar V-1 vertical bar/vertical bar V-2 vertical bar, vertical bar V-2 vertical bar/vertical bar V-1 vertical bar}<= c(s), for some constants c(p) and c(s). When G is 2-connected, we show that a solution with c(p)=1 and c(s)=3 always exists and can be found in polynomial time. Moreover, when G is 3-connected, we show that there is always a 'perfect' solution (a partition with p(V-1)=p(V-2)=0 and vertical bar V-1 vertical bar=vertical bar V-2 vertical bar, if vertical bar V vertical bar equivalent to 0(mod 4)), and it can be found in polynomial time. Our techniques can be extended, with similar results, to the case in which the weights are arbitrary (not necessarily +/- 1), and to the case that p(V)not equal 0 and the excess supply/demand should be split evenly. They also apply to the problem of partitioning a graph with two types of nodes into two large connected subgraphs that preserve approximately the proportion of the two types.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Density cluster based approach for controller placement problem in large-scale software defined networkings

Authors: Liao, J; Sun, H; Wang, J; Qi, Qi; Li, Kai; Li, T (2017) HERO ID: 4822716

[Less] Software Defined Networking (SDN) decouples control and data planes. The separation arises a problem . . . [More] Software Defined Networking (SDN) decouples control and data planes. The separation arises a problem known as the controller placement, i.e., how many and where controllers should be deployed. Currently, most works defined this problem as the multi-objective combinatorial optimization problem and used heuristic algorithms to search the optimal solution. However, these heuristic algorithms have the drawback of being easily trapped in local optimal solutions and consuming high time. In this paper, we propose an approach named as Density Based Controller Placement (DBCP), which uses a density-based switch clustering algorithm to split the network into several sub-networks. As switches are tightly connected within the same sub-network and less connected from the switches in other sub-networks, we deploy one controller in each sub-network. In DBCP, the size of each sub-network can be decided by the capacity of the controller deployed. Moreover, the optimal number of controllers is obtained according to the density-based clustering. We evaluate DBCP's performance on a set of 262 publicly available network topologies. The experimental results show that DBCP provides better performance than the state-of-the-art approaches in terms of time consumption, propagation latency, and fault tolerance. (C) 2016 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Enantioselective determination of (R)-zopiclone and (S)-zopiclone (eszopiclone) in human hair by micropulverized extraction and chiral liquid chromatography/high resolution mass spectrometry

Authors: Miyaguchi, H; Kuwayama, K (2017) HERO ID: 4822780

[Less] Zopiclone and its (S)-enantiomer (eszopiclone) are commonly prescribed for insomnia. Despite the high . . . [More] Zopiclone and its (S)-enantiomer (eszopiclone) are commonly prescribed for insomnia. Despite the high demand for enantioselective differentiation, the chiral analysis of zopiclone in hair has not been reported. In this study, a method for the enantioselective quantification of zopiclone in human hair was developed. The extraction medium and duration were optimized using real eszopiclone-positive hair samples. Specifically, micropulverized extraction with 3.0M ammonium phosphate buffer (pH 8.4) involving salting-out assisted liquid-liquid extraction with acetonitrile was utilized to minimize the degradation of zopiclone and for rapid and facile operation. On the other hand, recovery of the conventional solid-liquid extraction involved overnight soaking in 3.0M ammonium phosphate buffer (pH 8.4) was only 0.58±0.12% of the maximum recovery achieved by the present method due to the decomposition in the phosphate buffer. An excellent chiral separation (Rs=5.0) was achieved using a chiral stationary phase comprising cellulose tris(3,5-dichlorophenylcarbamate) and a volatile mobile phase of 10mM ammonium carbonate (pH 8.0)-acetonitrile (25:75, v/v). Detection was carried out using liquid chromatography/high resolution mass spectrometry (LC/HRMS) with electrospray ionization. A Q Exactive mass spectrometer equipped with a quadrupole-Orbitrap analyzer was used for detection. The concentration of 0.50pg/mg was defined as the lowest limit of quantification using 5mg of hair sample. Using the developed approach, the concentration of eszopiclone in hair after a single 2-mg dose was found to be 441pg/mg, which was higher than all the reported values regarding a single administration of zopiclone. After daily administration of racemic zopiclone (3.75mg/day), the concentrations of (R)-enantiomer and (S)-enantiomer in the black hair were 5.30-8.31ng/mg and 7.96-12.8ng/mg, respectively, and the concentration of the (S)-enantiomer was always higher than that of the (R)-enantiomer due to the enantioselective difference in the pharmacokinetics.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Use of dilute ammonia gas for treatment of 1,2,3-trichloropropane and explosives-contaminated soils

Authors: Coyle, CG; Waisner, SA; Medina, VF; Griggs, CS (2017) Journal of Environmental Management 204:775-782. HERO ID: 3863974

[Less] Laboratory studies were performed to test a novel reactive gas process for in-situ treatment of soils . . . [More] Laboratory studies were performed to test a novel reactive gas process for in-situ treatment of soils containing halogenated propanes or explosives. A soil column study, using a 5% ammonia-in-air mixture, established that the treatment process can increase soil pH from 7.5 to 10.2. Batch reactor experiments were performed to demonstrate contaminant destruction in sealed jars exposed to ammonia. Comparison of results from batch reactors that were, and were not, exposed to ammonia demonstrated reductions in concentrations of 1,2,3-trichloropropane (TCP), 1,3-dichloropropane (1,3-DCP), 1,2-dicholoropropane (1,2-DCP) and dibromochloropropane (DBCP) that ranged from 34 to 94%. Decreases in TCP concentrations at 23° C ranged from 37 to 65%, versus 89-94% at 62° C. A spiked soil column study was also performed using the same set of contaminants. The study showed a pH penetration distance of 30 cm in a 2.5 cm diameter soil column (with a pH increase from 8 to > 10), due to treatment via 5% ammonia gas at 1 standard cubic centimeter per minute (sccm) for 7 days. Batch reactor tests using explosives contaminated soils exhibited a 97% decrease in 2,4,6-trinitrotoluene (TNT), an 83% decrease in nitrobenzene, and a 6% decrease in hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). A biotransformation study was also performed to investigate whether growth of ammonia-oxidizing microorganisms could be stimulated via prolonged exposure of soil to ammonia. Over the course of the 283 day study, only a very small amount of nitrite generation was observed; indicating very limited ammonia monooxygenase activity. Overall, the data indicate that ammonia gas addition can be a viable approach for treating halogenated propanes and some types of explosives in soils.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

In Situ Synthesis of Coil-Coil Diblock Copolymer Nanotubes and Tubular Ag/Polymer Nanocomposites by RAFT Dispersion Polymerization in Poly(ethylene glycol)

Authors: Ding, Z; Ding, M; Gao, C; Boyer, C; Zhang, W (2017) HERO ID: 4384347

[Less] Hollow polymeric nanotubes have the potential to be employed as advanced nanomaterials in a variety . . . [More] Hollow polymeric nanotubes have the potential to be employed as advanced nanomaterials in a variety of applications; however, their synthesis from the assembly of coil-coil diblock copolymers (DBCPs) has typically been limited. Herein, we report a novel method for synthesis of coil-coil DBCP nanotubes by implementing RAFT dispersion polymerization in low molecular weight poly(ethylene glycol) (PEG). This method for the in situ synthesis of coil-coil DBCP nanotubes is particularly versatile and can be achieved with a range of block copolymers including poly(N-isopropylacrylamide)-block-polystyrene (PNIPAM-b-PS), poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS), and poly(methyl methacrylate)-block-polystyrene (PMMA-b-PS). Using this approach, several interesting coil coil DBCP tubular morphologies are observed, including single-wall nanotubes, multiwall nanotubes, and porous nanotubes. Furthermore, RAFT dispersion polymerization conducted in the presence of Ag nanoparticles can be used to yield complex tubular nanocomposites. The structure of these nanotubes such as the wall thickness and surface roughness can be tuned by varying the degree of polymerization (DP) of the solvophobic polystyrene block and/or the Ag fraction in the Ag/DBCP nanocomposites.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

About a linear polarization of comets: The phase-angle dependences of polarization degree

Authors: Shestopalov, DI; Golubeva, LF (2017) HERO ID: 3866090

[Less] The ground-based astronomic observations of comet cannot provide a proper phase angle coverage that . . . [More] The ground-based astronomic observations of comet cannot provide a proper phase angle coverage that is needed to estimate with a reasonable accuracy all of the attributes of comet polarization phase curve. To find the best approximation to the phase polarization dependences observed for comets, we apply a simple empiric formula that has already shown good results when operating with asteroid and lunar polarimetric curves (Shestopalov, 2004; Shestopalov and Golubeva, 2015). From the set of comets present in DBCP (Kiselev et al., 2006), we selected 20, for which the calculation of regular polarimetric curves (i.e. the phase angle polarization dependences with a low level of nonsteady activity) was possible. Within the phase angle coverage area for these 20 comets, a potential user can reproduce 82 best-fitting polarimetric phase curves in various spectral domains. Then we analyzed the properties of negative and positive polarization of the comets. The interrelation between the averaged polarimetric slope h at the inversion angle and wavelength was found. In general, the parameters of negative branch vary slightly from one comet to another. We found a close correlation between the maximum polarization degree P- max and the slope of the segment of polarimetric curve bounded by phase angles of 30 and 50. This finding allowed to adduce the evidence in support of the idea voiced by Chernova et al. (1993) about two types of comet with high and low Pmax. Moreover, we have found direct correlation between the maximum polarization degree of comets and their dust-to-gas ratio. The latter is actually a visual proof of assumptions voiced many years ago about a mutual effect of gas and dust on observed polarization of comets (see, for instance, a historical review in Kiselev et al., 2015). Thus, the polarimetric effect of resonant fluorescence should be completely eliminated from the phase-dependent polarization curve of comet in order to correctly interpret the physical properties of cometary dust. The simple method that we suggest to deconvolve polarimetric response from comets into "pure dusty" and "gaseous" polarimetric curves meets specific difficulties associated mainly with a shortage of data about the polarized luminescence of molecules and ions commonly present in the gaseous component of cometary atmospheres. (C) 2017 COSPAR. Published by Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

The hydrological effects of varying vegetation characteristics in a temperate water-limited basin: Development of the dynamic Budyko-Choudhury-Porporato (dBCP) model

Authors: Liu, Q; Mcvicar, TimR; Yang, Z; Donohue, RJ; Liang, L; Yang, Y (2016) HERO ID: 4822721

[Less] Vegetation patterns are affected by water availability, which, in turn, influences the hydrological . . . [More] Vegetation patterns are affected by water availability, which, in turn, influences the hydrological partitioning and regional water balance, especially in water-limited regions. Considering the important role of vegetation in partitioning the catchment water yield, the recently developed Budyko-Choudhury-Porporato (or BCP) model incorporated Porporato's model of key ecohydrological processes into Choudury's form of the Budyko hydroclimatic framework. Here we extend the steady state BCP model by incorporating dynamic ecohydrological processes into it and combining it with a typical bucket soil water balance model (resulting in the dynamic BCP, or dBCP, model). The dBCP model is used here to assess the impacts of vegetation on the water balance in a temperate water-limited basin (i.e., the Yellow River Basin (YRB) in north China), where growing season phenology is primarily constrained by low temperatures. The results show that: (i) the incorporation of dynamic growing season (f(s)) and dynamic effective rooting depth (Z(e)) conditions into the dBCP model improves results when compared to the original BCP model; (ii) dBCP model's results vary depending on time-step used (i.e., we tested mean-annual to monthly), which reflected the influence of catchment variables, e.g., catchment area, catchment-average air temperature, dryness index and Z(e); and (iii) actual evapotranspiration (E) is more, sensitive to changes in mean storm depth (alpha), followed by P, Z(e), and E-p. When taking into account observed variability of each of four ecohydrological variables, changes in Z(e) cause the greatest variability in E, generally followed by variability in P and alpha, and then E-p. The dBCP results indicate that incorporating dynamic ecohydrological processes into the Budyko framework can improve the estimation of inter annual variability of the regional water balance. This can help to understand the water requirement and to establish suitable water management strategies to adapt to climate change in the YRB. The dBCP model has modest forcing data requirements and can be applied to other basins globally. (C) 2016 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Localized Gene Expression Analysis during Sprouting Angiogenesis in Mouse Embryoid Bodies Using a Double Barrel Carbon Probe

Authors: Ito, H; Nashimoto, Y; Zhou, Y; Takahashi, Y; Ino, K; Shiku, H; Matsue, T (2016) Analytical Chemistry 88:610-613. HERO ID: 4452965

[Less] The mouse embryonic stem (ES) cell-derived angiogenesis model is widely used as a 3D model, reproducing . . . [More] The mouse embryonic stem (ES) cell-derived angiogenesis model is widely used as a 3D model, reproducing cell-cell interactions in the living body. Previously, many methods to analyze localized cellular function, including in situ hybridization and laser capture microdissection, have been reported. In this study, we achieved a collection of localized cells from the angiogenesis model in hydrogel. The gene expression profiles of the endothelial cells derived from mouse ES cells were evaluated. First, we collected localized cells from the live tissue model embedded in hydrogel using the double barrel carbon probe (DBCP) and quantified mRNA expression. Second, we found that vascular marker genes were expressed at a much higher level in sprouting vessels than in the central core of the embryoid body because the cells in sprouting vessels might significantly differentiate into endothelial linages, including tip/stalk cells. Third, the gene expression levels tended to be different between the top and middle regions in the sprouting vessel due to the difference in the degree of differentiation in these regions. At the top region of the vessel, both the tip and stalk cells were present. The cells in the middle region became more mature. Collectively, these results show that DBCP is very useful for analyzing localized gene expression in cells collected from 3D live tissues embedded in hydrogel. This technique can be applied to comprehensive gene expression analyses in the medical field.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Modulating Crystallinity of Poly(3-hexylthiophene) via Microphase Separation of Poly(3-hexylthiophene)-Polyisoprene Block Copolymers

Authors: Lim, H; Chao, ChiY; Su, WeiF (2015) HERO ID: 4822719

[Less] A series of poly(3-hexylthiophene)-block-polyisoprene (P3HT-b-PI) diblock copolymers (DBCP) and polyisoprene-block-poly(3-hexylthiophene)-block-polyisoprene . . . [More] A series of poly(3-hexylthiophene)-block-polyisoprene (P3HT-b-PI) diblock copolymers (DBCP) and polyisoprene-block-poly(3-hexylthiophene)-block-polyisoprene (PI-b-P3HT-b-PI) triblock copolymers (TBCP) with accurately controlled molecular architecture were synthesized via highly efficient coupling reaction between aldehyde end-functionalized P3HT and living anionic polyisoprene. The self-assembly behaviors, considering morphology and crystallinity, of the thermal annealed bulk samples of these DBCPs and TBCPs containing various PI content were systematically investigated. The DBCPs behaved very differently from most published P3HT BCP systems, showing elongated fibers with preserved crystallinity regardless of the PI fraction. More noteworthy, with PI fraction less than 40 wt %, the DBCPs exhibited parallel straight fibers longer than several micrometers accompanied by concurrent enhanced crystallinity. The unique microstructure of the DBCPs might originate from moderate microphase separation between P3HT and PI as well as high flexibility of PI to conduct the packing of P3HT. The TBCPs, by contrast, exhibited highly curved interdomain boundaries with significant depressed crystallinity, resembling P3HT diblock copolymers in the strong phase segregation regime, as more pronounced entanglement of the two terminal PI segments would restrict the movement of P3HT.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Assessing reproductive toxicity of two environmental toxicants with a novel in vitro human spermatogenic model

Authors: Easley, CA; Bradner, JM; Moser, A; Rickman, CA; Mceachin, ZT; Merritt, MM; Hansen, JM; Caudle, WM (2015) Stem Cell Research 14:347-355. HERO ID: 4452973

[Less] Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis . . . [More] Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1,2,dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability, whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format.