Accounting for water levels and black carbon-inclusive sediment-water partitioning of organochlorines in Lesser Himalaya, Pakistan using two-carbon model

Abstract

This study was designed to monitor organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in riverine water of Lesser Himalaya along the altitude. Further, the sediment-water partitioning employing organic carbon and black carbon models were assessed. Results revealed higher water levels of organochlorine pesticides (0.07–41.4 ng L⁻¹) and polychlorinated biphenyls (0.671–84.5 ng L⁻¹) in Lesser Himalayan Region (LHR) of Pakistan. Spatially, elevated levels were observed in the altitudinal zone (737–975 masl) which is influenced by anthropogenic and industrial activities. Sediment-water partitioning of OCPs and PCBs were deduced using field data by employing one-carbon (f_OCK_OC) and two-carbon Freundlich models (f_OCK_OC + f_BCK_BCC_W^nF−1). Results suggested improved measured vs predicted model concentrations when black carbon was induced in the model and suggested adsorption to be the dominant mechanism in phase partitioning of organochlorines in LHR.

The impacts of environmental governance on political turnover of municipal party secretary in China

Abstract

Political incentive is one of the most efficient methods to promote local officials to push for both economic growth and environmental progress in the context of China. Since previous scholars have never investigated the relationships between political turnover and environmental governance at the municipal level, in this work, we proxy pollution by SO₂, COD, SOOT, and NHx and examine whether environmental performance affects the political turnover of the municipal party secretary by exploiting a panel conditional logit with a fixed-effect model for the period 2002–2013. The results indicate that environmental performance does not significantly impact the turnover of municipal party secretaries, offering evidence that an increase of SO₂ is associated with the likelihood of promotion under the panel multinomial logit approach. However, a higher GDP growth rate plays the determinant factor affecting the promotion of China's municipal party secretaries. Specific policy recommendations are proposed in accordance with our empirical findings.

Micro-bubbles enhanced breakage warning for hollow fiber membrane integrity with a low-cost real-time monitoring device

Abstract

A low-cost device was developed to monitor the integrity of hollow fiber membrane by real-time online detecting and measuring air bubbles in the permeate flow. When a breakage occurs in the fiber membrane system, air bubbles will find their ways to enter the permeate flow. The monitoring device consists of two pairs of platinum probes attached to a pipe, along which the permeate flows. Membrane's breakage was identified by the voltage changes between the two pairs of probes when air bubbles in the permeate touch them. There was no addition of any other chemicals or materials into the system that would jeopardize final products of the membrane process. Experimental results showed that the voltage signal changes before and after a breach of membrane were obvious in the normal operation conditions. The smallest diameter of the bubbles that can be detected by the monitoring device was 50 μm, which was captured and identified with a high-speed camera. Furthermore, the sensitivity of device with two pairs of probes improved by 5~9% over that with one pair of probes. Finally, cost of the proposed device was roughly estimated only about 70 US dollars and the detection result was highly consistent with that obtained with the prevailing particle counters of several thousand US dollars.

A 35-Year-Old Human Immunodeficiency Virus-Infected Male With Abdominal Pain and a Knot in His Abdomen

(See page 150 for the Photo Quiz.)

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A 35-Year-Old Human Immunodeficiency Virus-Infected Man With Abdominal Pain and a Knot in His Abdomen

(See pages 151–2 for the Answer to the Photo Quiz.)

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In the Literature

In Memoriam, Fred Gordin, MD, 1951–2018

Fred Gordin, MD. Photo by Anne Willoughby, MD. Reprinted with permission

Explanation and abstraction from a backward-error analytic perspective

Abstract

We argue that two powerful error-theoretic concepts (backward error and conditioning) provide a general framework that satisfactorily accounts for key aspects of the explanation of physical patterns. This method gives an objective criterion to determine which mathematical models in a class of (possibly idealized) neighboring models are just as good as the exact one. The method also emphasizes that abstraction is essential for explanation and provides a precise conceptual framework that determines whether a given abstraction is explanatorily relevant and justified. Hence, it increases our epistemological understanding of how one should go about reconstructing scientific practices by making clear that, at a fundamental level, a key aspect of mathematical modeling consists in exactly solving nearby problems.

Chemicals from textiles to skin: an in vitro permeation study of benzothiazole

Abstract

Despite the possible impact on human health, few studies have been conducted to assess the penetration and accumulation of contaminants in the skin after a prolonged contact with textile materials. In previous studies, we have shown that benzothiazole and its derivatives, as well as other potentially hazardous chemicals, often are present as textile contaminants in clothes available on the retail market. Since benzothiazole is a common contaminant in clothes, these can be a possible route for human chemical exposure, both systemic and onto the skin. To investigate this potential exposure, Franz-type and flow-through cells were used for the permeation studies together with a Strat-M® artificial membranes. Experiments were performed using solutions of benzothiazole, as well as contaminated textile samples in the donor chamber. Benzothiazole was demonstrated to penetrate through, as well as being accumulated in the membrane mimicking the skin. After 24 h, up to 62% of benzothiazole was found in the acceptor cell, while up to 37% was found absorbed in the skin mimicking membrane. It also was shown that there was release and permeation from contaminated fabrics. The results indicate that benzothiazole can be released from textile materials, penetrate through the skin, and further enter the human body. This will possibly also apply to other chemical contaminants in textiles, and the results of this study indicate that the presence of these textile contaminants entails potential health risks. A rough risk assessment was made for clothing textiles according to Environmental Protection Agency (EPA) and European regulations for carcinogenic and non-carcinogenic compounds, using literature data for benzothiazole.