Breaking barriers in passive sampling: the potential of PTFE membranes in the monitoring of hydrophilic micropollutants

Passive samplers are key tools to sample hydrophilic micropollutants in water. Two main approaches address hydrodynamics’ influence: (1) determining site-specific sampling rate (RS) by characterizing kw, the mass transfer coefficient of the water-boundary layer (WBL), and (2) reducing WBL impact using a diffusive material to control the uptake. The first requires calibration data and the second has only been achieved using fragile diffusive material. This study assesses the transfer of hydrophilic contaminants through polytetrafluoroethylene (PTFE; 30 μm thick), a new membrane material with lower sorption than commonly used polyethersulfone (PES). Combined for the first time in a Chemcatcher-like configuration, we calibrated the modified samplers for 44 micropollutants to provide RS – kw relationships for in-situ RS determination (approach 1). Micropollutants accumulated over 2000 times more on the sorbent than on PTFE. PTFE-based RS (0.027 to 0.300 L day-1) were 2.5 higher than previously reported with PES. Membrane property measurements (porosity, tortuosity) indicated that accumulation is primarily controlled by the membrane. Extrapolation indicated that using thicker PTFE membranes (≥ 100 μm) would shift uptake control entirely to the membrane in river conditions (approach 2). This finding could enable RS prediction based on contaminants properties, thus representing a significant advancement in passive sampling

An improved Chemcatcher-based method for the integrative passive sampling of 44 hydrophilic micropollutants in surface water – Part A: Calibration under four controlled hydrodynamic conditions

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Predicting Survey Response with Quotation-based Modeling: A Case Study on Favorability towards the United States

The acquisition of survey responses is a crucial component in conducting research aimed at comprehending public opinion. However, survey data collection can be arduous, time-consuming, and expensive, with no assurance of an adequate response rate. In this paper, we propose a pioneering approach for predicting survey responses by examining quotations using machine learning. Our investigation focuses on evaluating the degree of favorability towards the United States, a topic of interest to many organizations and governments. We leverage a vast corpus of quotations from individuals across different nationalities and time periods to extract their level of favorability. We employ a combination of natural language processing techniques and machine learning algorithms to construct a predictive model for survey responses. We investigate two scenarios: first, when no surveys have been conducted in a country, and second when surveys have been conducted but in specific years and do not cover all the years. Our experimental results demonstrate that our proposed approach can predict survey responses with high accuracy. Furthermore, we provide an exhaustive analysis of the crucial features that contributed to the model's performance. This study has the potential to impact survey research in the field of data science by substantially decreasing the cost and time required to conduct surveys while simultaneously providing accurate predictions of public opinion.Comment: IEEE Swiss Conference on Data Science (SDS) 202

Purification of recombinant proteins by chemical removal of the affinity tag

The efficient removal of a N-or C-terminal purification tag from a fusion protein is necessary to obtain a protein in a pure and active form, ready for use in human or animal medicine. Current techniques based on enzymatic cleavage are expensive and result in the presence of additional amino acids at either end of the proteins, as well as contaminating proteases in the preparation. Here we evaluate an alternative method to the one-step affinity/protease purification process for large-scale purification. It is based upon the cyanogen bromide (CNBr) cleavage at a single methionine placed in between a histidine tag and aPlasmodium falciparum antigen. The C-terminal segment of the circumsporozoite polypeptide was expressed as a fusion protein with a histidine tag inEscherichia coli purified by Ni-NAT agarose column chromatography and subsequently cleaved by CNBr to obtain a polypeptide without any extraneous amino acids derived from the cleavage site or from the affinity purification tag. Thus, a recombinant protein is produced without the need for further purification, demonstrating that CNBr cleavage is a precise, efficient, and low-cost alternative to enzymatic digestion, and can be applied to large-scale preparations of recombinant protein

RhoB regulates cell migration through altered focal adhesion dynamics

The Rho GTPase RhoB has been shown to affect cell migration, but how it does this is not clear. Here we show that cells depleted of RhoB by RNAi are rounded and have defects in Rac-mediated spreading and lamellipodium extension, although they have active membrane ruffling around the periphery. Depletion of the exchange factor GEF-H1 induces a similar phenotype. RhoB-depleted cells migrate faster, but less persistently in a chemotactic gradient, and frequently round up during migration. RhoB-depleted cells have similar numbers of focal adhesions to control cells during spreading and migration, but show more diffuse and patchy contact with the substratum. They have lower levels of surface β1 integrin, and β1 integrin activity is reduced in actin-rich protrusions. We propose that RhoB contributes to directional cell migration by regulating β1 integrin surface levels and activity, thereby stabilizing lamellipodial protrusions

An improved Chemcatcher-based method for the integrative passive sampling of 44 hydrophilic micropollutants in surface water – Part B: Field implementation and comparison with automated active sampling

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Prominent role of the Ig-like V domain in trans-interactions of nectins. Nectin3 and nectin 4 bind to the predicted C-C'-C"-D beta-strands of the nectin1 V domain.

Nectins form a family of integral molecules that belong to the immunoglobulin superfamily. Their ectodomain is made of three Ig-like domains (V, C, C). This family comprises at least five members, namely nectin1, -2, -3, -4, and poliovirus receptor (PVR), that are involved in different physiological and pathological processes. (i) Nectins are adhesion molecules localized at adherens junctions in epithelial cells. (ii) Some nectins act as poliovirus or alpha-herpesvirus receptors (nectin1). (iii) Nectin1 mutations are involved in orofacial developmental abnormalities in humans. Adhesion properties of nectins are mediated by Ca(2+)-independent homophilic and heterophilic processes through ectodomain trans-interactions. We have described a nectin trans-hetero-interaction network: nectin3 binds to nectin1, nectin2, and PVR; nectin1 also binds to nectin4. In the present study we compared the affinities of the different trans-interactions mediated by nectin1. We found that the K(D) of nectin1/nectin3 and nectin1/nectin4 interactions is 1 and 100 nm, respectively, whereas the K(D) of the nectin1-mediated homophilic interaction is 1 microm. We show that nectin1/nectin3 and nectin1/nectin4 trans-hetero-interactions were mediated through trans V to V domain interactions, whereas C domains contributed to increase the affinity of the interaction. Nectin3 and nectin4 share a common binding region in the nectin1 V domain: (i) nectin3 strongly competed with nectin4 binding, (ii) nectin3 and nectin4 binding to nectin1 was reduced by a number of monoclonal antibodies directed against the nectin1 V domain, and (iii) the glycoprotein D of herpes simplex virus-1 that binds to the V domain of nectin1 reduced nectin3 and nectin4 binding. Finally, using chimeric nectin1/PVR receptors where PVR V domain beta-strands were substituted with the corresponding regions of nectin1, the nectin3 and nectin4 minimal binding region on nectin1 V domain was mapped to the C-C'-C"-D beta-strands

The role of forensic science in the generation of intelligence to address environmental water contamination problems

Water contamination is a growing concern in society. New environmental laws are being enacted to define intolerable human activities, and their enforcement is increasingly supported by forensic science. However, water contamination is a broader security issue that is not only caused by illegal human behavior.Risk-based approaches are needed to prevent (re)occurrence of incidents and minimize their negative consequences. This can be achieved through the formalization of a monitoring process producing intelligence (i.e., actionable knowledge), crucial to detect recurring incidents, and guiding decision-makers in their choice of preventive and responsive actions. In this perspective,forensic science has a key role to play in integrating vestiges from water-contaminating activities (i.e., traces) in such a problem-solving process. Information conveyed by traces allows detecting similarities among contamination events (i.e., patterns), inferring common causes, and better understanding of mechanisms and consequences of water contamination. The different stages of the process will be described and illustrated through a real case example.Current barriers to the implementation of such a process are then discussed,showing how systemic issues and complexity may prevent the establishment of links across contamination events, thus negatively impacting the generation of intelligence. To overcome these obstacles, we underline the importance to initiate local and size-limited approaches by implementing relatively simple and flexible systems. New knowledge can be used to improve local situations and help stakeholders to understand the benefits of such a process; then, by a bottom-up iterative learning process, the approach can be given a greater ambition at a larger scale