Reaction products of aquatic humic substances with chlorine.

A major concern of the chlorination of aquatic humic materials is the ubiquitous production of trihalomethanes. A large number of other chlorinated organic compounds, however, have been shown to be formed by chlorine's reaction with humic substances. In this study, humic material was concentrated from a coastal North Carolina lake and chlorinated at a chlorine to carbon mole ratio of 1.5 at pH 12. A high pH was necessary for complete dissolution of the humic material and for production of adequate quantities of oxidation and chlorination products for extraction, separation and mass spectrometric identification. After concentration in ether, samples were methylated, separated with a 50-m OV-17 glass capillary column or a 25 m SP-2100 fused-silica column and identified. A Hewlett-Packard 5710A gas chromatograph interfaced to a VG Micromass 7070F double-focusing mass spectrometer was used. Low resolution, accurate mass measurements were made with a combined EI-Cl source. The ability to do low resolution, accurate mass measurements made possible a rapid scan function necessary for capillary column gas chromatography. Accurate mass measurements allowed increased confidence in the identification of compounds, most of which are not available as standards. The products identified in these studies were chlorinated aliphatic straight-chain acids dominated by di- and trichloroacetic acid and the chlorinated dicarboxylic acids: succinic, fumaric and maleic acids. Chlorinated and unchlorinated aliphatic mono- and dicarboxylic acids and unchlorinated polycarboxylic aromatic acids comprise the remaining bulk of the compounds identified

Intrinsic Energy Localization through Discrete Gap Breathers in One-Dimensional Diatomic Granular Crystals

We present a systematic study of the existence and stability of discrete breathers that are spatially localized in the bulk of a one-dimensional chain of compressed elastic beads that interact via Hertzian contact. The chain is diatomic, consisting of a periodic arrangement of heavy and light spherical particles. We examine two families of discrete gap breathers: (1) an unstable discrete gap breather that is centered on a heavy particle and characterized by a symmetric spatial energy profile and (2) a potentially stable discrete gap breather that is centered on a light particle and is characterized by an asymmetric spatial energy profile. We investigate their existence, structure, and stability throughout the band gap of the linear spectrum and classify them into four regimes: a regime near the lower optical band edge of the linear spectrum, a moderately discrete regime, a strongly discrete regime that lies deep within the band gap of the linearized version of the system, and a regime near the upper acoustic band edge. We contrast discrete breathers in anharmonic FPU-type diatomic chains with those in diatomic granular crystals, which have a tensionless interaction potential between adjacent particles, and highlight in that the asymmetric nature of the latter interaction potential may lead to a form of hybrid bulk-surface localized solutions

A Demographic Model of an Endangered Florida Native Bromeliad (Tillandsia utriculata)

The large, long-lived, epiphytic bromeliad Tillandsia utriculata is currently listed as state-endangered in Florida due to significant population reduction from predation by an invasive weevil, Metamasius callizona. We have developed a novel demographic model of a population of T. utriculata in Myakka River State Park (MRSP) in Sarasota, Florida using a stage-structured matrix model. Analysis of the model revealed conditions for population viability over a variety of parameter scenarios. Model analysis showed that without weevil predation the minimum germination rate required for population viability is low (4–16%), and that given a viable population at structural equilibrium we would expect to find 15 cm in flower or post-flowering each year. Additionally, the model presented here provides a basis for further analyses which explore specific conservation strategies

Analysis of Energy Recovery Ventilator Savings for Texas Buildings

This analysis was conducted to identify the energy cost savings from retrofitting Texas buildings with air-to-air ERV (Energy Recovery Ventilator) systems. This analysis applied ERV and psychrometric equations in a bin-type procedure to determine the energy and costs required to condition outside air to return-air conditions. This analysis does not consider interactions with the air-handling system; therefore the effects of economizers, reheat schemes, variable flow rates and other adaptive components were not considered. This analysis demonstrates that ERV cost-effectiveness is largely dependent upon the building location in Texas (i.e., climate conditions) and outside air fraction: • For a typical laboratory building that requires 100% outside air, an ERV could save roughly $1.00 to$1.50 per cubic foot per minute (CFM) of outside air during a one year period. • For a typical office building that only requires 10% outside air, an ERV could save up to $1.00 per CFM of outside air over the period of one year

Ultrasonic biological effect exposure system

ABSTRACT. data which could be used in assessing the biological risk from exposure to ultrasonic energy. The system can reproduce the ultrasonic signals of medical diagnostic and therapeutic equipment at cmparable or greater intensities. Signal synthesis is at low electrical powers (<O dBm) with linear amplification of the signal to the desired level by a high power, broadband amplifier. minicomputer controls the exposure time and the net electrical power to the ultrasonic transducer assembly through an interface to a programmable frequency synthesizer. monitored by a dual directional coupler which, in turn, is monitored by the minicomputer with an r.f. digital voltmeter. controlled, water or saline filled exposure tank. tank serves as an ultrasonic absorber to minimize standing waves. measured by the bouyant float technique which is used to determine the ultrasonic transducer assembly efficiency of converting the net electrical power into ultrasonic power. hydrophone technique is used to obtain either axial or three dimensional perspective plots of the ultrasonic field. animal exposures such as 25 to 40 gram mice and liquid suspension exposures. An ultrasonic biological effect exposure system was developed to provide experimental A The net electrical power is The ultrasonic transducer assembly is mounted at one end of a temperature A castor oil load at the far end o f the exposure The total ultrasonic power is A scanning The exposure system can support two general types of experiments, viz., small -INTRODUCTION Even though the use of ultrasound continues to increase (Erikson yet to develop a reliable assessment of the risk associated with exposure to ultrassund (O'Brien 1972). One major reason i s that insufficient qualitative and quantitative information exists with respect to dose-effect relationships and interaction mechanisms (Reid and Sikov, 1972)

Preconceptional antithyroid peroxidase antibodies, but not thyroid-stimulating hormone, are associated with decreased live birth rates in infertile women

OBJECTIVE: To study whether preconceptual thyroid-stimulating hormone (TSH) and antithyroid peroxidase (TPO) antibodies are associated with poor reproductive outcomes in infertile women. DESIGN: Secondary analysis of data from two multicenter, randomized, controlled trials conducted by the Reproductive Medicine Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Multivariable logistic regression analyses were performed to assess the association between preconceptual TSH levels and anti-TPO antibodies. SETTING: Not applicable. PATIENT(S): Serum samples from 1,468 infertile women were utilized. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Cumulative conception, clinical pregnancy, miscarriage, and live birth rates were calculated. RESULT(S): Conception, clinical pregnancy, miscarriage, and live birth rates did not differ between patients with TSH ≥2.5 mIU/L vs. TSH < 2.5 mIU/L. Women with anti-TPO antibodies had similar conception rates (33.3% vs. 36.3%) but higher miscarriage rates (43.9% vs. 25.3%) and lower live birth rates (17.1% vs. 25.4%) than those without anti-TPO antibodies. Adjusted, multivariable logistic regression models confirmed elevated odds of miscarriage (odds ratio 2.17, 95% confidence interval 1.12-4.22) and lower odds of live birth (oddr ratio 0.58, 95% confidence interval 0.35-0.96) in patients with anti-TPO antibodies. CONCLUSION(S): In infertile women, preconceptional TSH ≥2.5 mIU/L is not associated with adverse reproductive outcomes; however, anti-TPO antibodies are associated with increased risk of miscarriage and decreased probability of live birth. CLINICAL TRIAL REGISTRATION NUMBER: PPCOS II NCT00719186; AMIGOS NCT01044862

Baseline AMH Level Associated With Ovulation Following Ovulation Induction in Women With Polycystic Ovary Syndrome

Anti-Müllerian hormone (AMH) reduces aromatase activity and sensitivity of follicles to FSH stimulation. Therefore, elevated serum AMH may indicate a higher threshold for response to ovulation induction in women with polycystic ovary syndrome (PCOS). This study sought to determine the association between AMH levels and ovulatory response to treatment among the women enrolled into the Pregnancy in PCOS II (PPCOS II) trial. This was a secondary analysis of data from a randomized clinical trial in academic health centers throughout the United States Participants: A total of 748 women age 18-40 years, with PCOS and measured AMH levels at baseline, were included in this study. Couples were followed for up to five treatment cycles to determine ovulation (midluteal serum progesterone > 5 ng/mL) and the dose required to achieve ovulation. A lower mean AMH and AMH per follicle was observed among women who ovulated compared with women who never achieved ovulation during the study (geometric mean AMH, 5.54 vs 7.35 ng/mL; P = .0001; geometric mean AMH per follicle, 0.14 vs 0.18; P = .01) after adjustment for age, body mass index, T, and insulin level. As AMH levels increased, the dose of ovulation induction medication needed to achieve ovulation also increased. No associations were observed between antral follicle count and ovulation. These results suggest that high serum AMH is associated with a reduced response to ovulation induction among women with PCOS. Women with higher AMH levels may require higher doses of medication to achieve ovulation