ORGANIC CONTAMINANTS DESTRUCTION USING THE UV/FREE CHLORINE PROCESS: MECHANISMS AND MODELING

Advanced oxidation processes (AOPs) are effective technologies to oxidize recalcitrant organic contaminants in the aqueous phase. The UV/free chlorine process has gained attention as a promising AOP technology, and it generates various reactive radicals (i.e. HO∙, Cl∙, Cl2-∙ and ClO∙) at room temperature and pressure. These electrophilic radicals eventually mineralize refractory organic contaminants into CO2 and H2O. Compared with other common AOPs (e.g. UV/H2O2 and UV/Persulfate processes), the UV/free chlorine process has many advantages, for example (1) it has much lower chemical reagent costs; (2) it has higher energy efficiency; (3) it is only slightly impacted by chloride ions (Cl-) (We found Cl- significantly inhibits the effectiveness of the UV/Persulfate process). For large scale applications, understanding the degradation mechanisms is critical to the design of the UV/free chlorine process that has the lowest energy consumption and greatest toxicity reduction. A number of related studies have shed light on the degradation of some selected organic compounds (e.g., atrazine, naproxen, etc.). However, these previous studies of the UV/free chlorine process have not comprehensively examined the mechanistically complex radicals-initiated chain reactions. Many researches have conducted experiments to determine the degradation mechanisms. However, these experimental studies are very time consuming and expensive. With respect to developing kinetic models that can simulate the reaction pathways in the UV/free chlorine process, most studies have used simplified lumped reactions or invoked the simplified pseudo steady state assumption because the rate constants between reactive radicals and organic compounds are unknown. Accordingly, conducting experiments and developing simplified kinetic models would be impossible to fully elucidate the oxidation mechanisms of all organic contaminants that may be found in the aqueous phase (Chemical Abstracts Service lists about more than 147 million compounds). To overcome the above-mentioned challenges, we developed a first principles-based kinetic model to predict the oxidation of organic compounds in the UV/free chlorine process. First, we collected photolysis and chemical reactions that describe the oxidation of target organic compounds from literature. Second, we developed a rate constants estimator to predict the rarely reported second-order rate constants between reactive radicals and organic compounds (i.e. kHO∙/R, kCl∙/R, kCl2-∙/R and kClO∙/R). kHO∙/R was estimated by the group contribution method (GCM). kCl∙/R, kCl2-∙/R and kClO∙/R were estimated by using the genetic algorithm that was fit to our experimental data (i.e. experimental observed time-dependent concentration profiles of target organic compounds). Third, we developed a stiff ordinary differential equations solver using Gear’s method to predict the time-dependent concentration profiles of target organic compounds, and our prediction results agreed with our experimental data for various operational conditions. Accordingly, our first principles-based kinetic model was successfully verified using our experimental data. Based on our UV/free chlorine kinetic model, we developed four quantitative structure activity relationships using Hammett constants of organic compounds and our predicted rate constants. We then determined relative contribution of these reactive radicals and photolysis, and, we found ClO∙ was the dominant radicals for organic contaminants oxidation. We also optimized the operational conditions (i.e. UV intensity and free chlorine dosage) that has the lowest energy consumption. Furthermore, we successfully implemented graph theory to develop a computerized pathway generator, which was built based on the predefined reaction mechanisms from experimental observations. The pathway generator can automatically predict all possible reactions and byproducts/intermediates that are involved in the degradation of target organic contaminants during the UV/free chlorine process (e.g. the degradation of TCE involves more than 200 byproducts /intermediates and more than 1,000 reactions). Therefore, the pathway generator significantly advances our understanding about the degradation pathways. However, we have noticed that it is difficult to estimate the rate constants of all possible involved reactions at current stage, because we only have very limited amount of experimental data (e.g., we do not have data on peroxyl radicals reactions) to develop a GCM. Consequently, future work will mainly focus on developing new methods (e.g. quantum chemistry) to estimate the rate constants of all possible involved reactions, and then predicting the time-dependent concentration profiles of byproducts. Finally, we investigated the disinfection byproducts (DBPs) and disinfection byproducts formation potentials (DBPFPs) in the UV/free chlorine process. In practical applications, natural organic matter can react with residual free chlorine to produce toxic DBPs. As a result, both the micropollutants and the DBPFPs must be decreased. Therefore, we need determine the controlling factor (i.e., organic contaminant destruction or DBPFPs reduction) in the design of the UV/free chlorine system. Overall, our study can be used to design the most cost-effective UV/free chlorine process.Ph.D

Antimicrobial resistance and the growing threat of drug-resistant tuberculosis

The purpose of this study was to investigate the associations between birth weight, chest circumference, and lung function in preschool children from e-waste exposure area. A total of 206 preschool children from Guiyu (an e-waste recycling area) and Haojiang and Xiashan (the reference areas) in China were recruited and required to undergo physical examination, blood tests, and lung function tests during the study period. Birth outcome such as birth weight and birth height were obtained by questionnaire. Children living in the e-waste-exposed area have a lower birth weight, chest circumference, height, and lung function when compare to their peers from the reference areas (all p value <0.05). Both Spearman and partial correlation analyses showed that birth weight and chest circumference were positively correlated with lung function levels including forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). After adjustment for the potential confounders in further linear regression analyses, birth weight, and chest circumference were positively associated with lung function levels, respectively. Taken together, birth weight and chest circumference may be good predictors for lung function levels in preschool children

Causal Reasoning of Entities and Events in Procedural Texts

Entities and events are crucial to natural language reasoning and common in procedural texts. Existing work has focused either exclusively on entity state tracking (e.g., whether a pan is hot) or on event reasoning (e.g., whether one would burn themselves by touching the pan), while these two tasks are often causally related. We propose CREPE, the first benchmark on causal reasoning of event plausibility and entity states. We show that most language models, including GPT-3, perform close to chance at .35 F1, lagging far behind human at .87 F1. We boost model performance to .59 F1 by creatively representing events as programming languages while prompting language models pretrained on code. By injecting the causal relations between entities and events as intermediate reasoning steps in our representation, we further boost the performance to .67 F1. Our findings indicate not only the challenge that CREPE brings for language models, but also the efficacy of code-like prompting combined with chain-of-thought prompting for multihop event reasoning.Comment: In Findings of EACL 202

Short-term outcomes of robot-assisted versus video-assisted thoracoscopic surgery for non-small cell lung cancer patients with neoadjuvant immunochemotherapy: a single-center retrospective study

BackgroundNeoadjuvant immunochemotherapy has been increasingly applied to treat non-small cell lung cancer (NSCLC). However, the comparison between robotic-assisted thoracoscopic surgery (RATS) and video-assisted thoracoscopic surgery (VATS) in the feasibility and oncological efficacy following neoadjuvant immunochemotherapy is scarce. This study aims to assess the superiorities of RATS over (VATS) concerning short-term outcomes in treating NSCLC patients with neoadjuvant immunochemotherapy.MethodsNSCLC patients receiving RATS or VATS lobectomy following neoadjuvant immunochemotherapy at Shanghai Chest Hospital from 2019 to 2022 were retrospectively identified. Baseline clinical characteristics, perioperative outcomes, and survival profiles were analyzed.ResultsForty-six NSCLC patients with neoadjuvant immunochemotherapy were included and divided into the RATS (n=15) and VATS (n=31) groups. The baseline clinical characteristics and induction-related adverse events were comparable between the two groups (all p&gt;0.050). The 30-day mortality in the RATS and VATS groups were 0% and 3.23%, respectively (p=1.000). Patients undergoing RATS were associated with reduced surgical-related intensive unit care (ICU) stay than those receiving VATS (0.0 [0.0-0.0] vs. 0.0 [0.0-1.0] days, p=0.026). Moreover, RATS assessed more N1 LNs (6.27 ± 1.94 vs 4.90 ± 1.92, p=0.042) and LN stations (3.07 ± 1.03 vs 2.52 ± 0.57, p=0.038) compared with VATS. By comparison, no difference was found in surgical outcomes, pathological results, and postoperative complications between the RATS and VATS groups (all p&gt;0.050). Finally, RATS and VATS achieved comparable one-year recurrence-free survival (82.96% vs. 85.23%, p=0.821) and the timing of central nervous system, LN, and bone recurrences (all p&gt;0.050).ConclusionRATS is safe and feasible for NSCLC patients with neoadjuvant immunochemotherapy, reducing surgical-related ICU stay, assessing increased N1 LNs and stations, and achieving similar survival profiles to VATS

Larval parasitoids of agromyzid leaf miner genus Liriomyza in the southern Thailand : species and their host plants

Larval parasitoids of the leaf miner genus Liriomyza were studied in six provinces of southern Thailand, Songkhla, Phatthalung, Nakhon Si Thammarat, Trang, Satun and Pattani, from April 2000- March 2001. Two families of hymenopteran parasitoids, Eulophidae and Braconidae, were found. The eulophid included Asecodes sp. nr. notandus (Sivestri), Cirrospilus ambiguus Hanssan & LaSalle, Hemiptarsenus variconis (Girault), Neochrysocharis formosa (Westwood) and Quadrastichus sp. nr. liriomyzae Hanssan & LaSalle. There was only one braconid species, Opius dissitus (Muesebeck). Among these, A. sp. nr. notandus was found in highest frequency while H. variconis had the widest range of host plants. The parasitoids were found on 14 host plant species. Vigna sesquipedalis was able to be used by all six species of parasitoids. It was also the host plant most often used by the parasitoids in this study

Degradation of Trimethoprim Using the UV/Free Chlorine Process: Influencing Factors and Optimal Operating Conditions

Trimethoprim (TMP) is a pharmaceutical compound, which is commonly found in the water environment. The UV/chlorine process forms several reactive species, including hydroxyl radicals (HO•) and reactive chlorine species, to degrade contaminants. The influencing factors and the optimal operational conditions for the degradation of TMP by the UV/chlorine process were investigated. The degradation of TMP was much faster by the UV/chlorine process as compared to the UV alone or free chlorine alone process. A kinetic model was developed to simulate the degradation of TMP and determine the unknown rate constants. This study also predicted the relative contributions of each of the reactive species and photolysis using the developed kinetic model. It was found that the ClO• radical was the major reactant responsible for the degradation of TMP. Furthermore, the most important finding was the identification of the best operational conditions. The best operational conditions resulted in the lowest use of energy and electrical energy per order (EE/O), namely, (1) for the ultrapure water, the optimum intensity of the UV light and the free chlorine dosage were 2.56 Einstein/L·s and 0.064 mM, respectively, with a minimum EE/O of 0.136 kWh/m3; and (2) for the water matrix containing 3 mg/L NOM, the optimum intensity of the UV light and the free chlorine dosage were 3.45 Einstein/L s and 0.172 mM, respectively, with a minimum EE/O of 0.311 kWh/m3

Functionalized hollow siliceous spheres for VOCs removal with high efficiency and stability

Functionalized hollow siliceous spheres (HSSs) have been prepared by surface modification with trimethylchlorosilane (TMCS) for the removal of volatile organic compounds (VOCs). The resultant HSSs-TMCS possesses a uniform and well-dispersed hollow spherical structure, high surface area, large total pore volume, high VOCs adsorption capacity, and small water vapor adsorption capacity. The adsorption and desorption performance of HSSs-TMCS under static (n-hexane and 93# gasoline) and dynamic (n-hexane) conditions was investigated. Compared with commercial silica gel (SG) and activated carbon (AC), HSSs-TMCS show higher capacity of adsorbing n-hexane and 93# gasoline with good stability and low water vapor adsorption capacity under static adsorption conditions, higher dynamic adsorption capacity and stable breakthrough time under dynamic adsorption conditions. The high efficiency and stability of functionalized HSSs are associated with their unique hollow morphology and structure parameters. The designed HSSs-TMCS with high VOCs removal capacity and recyclability are promising candidates for the treatment of air pollution

Supramolecular interactions of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co- thiophene] with single-walled carbon nanotubes

Efficient selective extraction of semiconducting single-walled carbon nanotubes (s-SWCNTs) from as-synthesized SWCNTs is essential for their electronic and photovoltaic applications. In this study, we used a relatively simple copolymer backbone structure of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-thiophene] (PFT) for the selective extraction of s-SWCNTs from HiPCO SWCNTs. The absorption and Raman spectroscopies indicated that the PFT-sorted s-SWCNTs had high purity which was far beyond the sensitivity of the spectrometers. Photoluminescence excitation spectroscopy showed that PFT mainly extracted the chiralities of (n,m)=(9,5), (8,6), (7,5), and (10,5) s-SWCNTs with the ratios of about 53.1%, 24.8%, 11.5%, and 10.5%, respectively. Both steady-state and transient optical spectroscopies suggested that there was a strong interaction between PFT and s-SWCNTs. Molecular dynamics simulation results agreed well with the experimental data. Additionally, the photoinduced energy transfer behavior of the PFT-wrapped s-SWCNT resultant hybrid was assessed. This work indicated that the prepared PFT-wrapped s-SWCNT hybrid material was attractive for organic photovoltaic devices