Effective and selective recovery of Au(III) from WPCBs using quaternary phosphonium adsorbent synthesized by adjusting steric hindrance.

With the gradual depletion of natural gold ore, waste printed circuit boards (WPCBs) have become one of the most attractive alternatives to gold ore. Here, a series of quaternary phosphonium adsorbents with a large size were successfully synthesized by adjusting the number of functional groups and carbon chain length of functional monomers, which can be used for selective recovery of gold(III) from WPCBs leaching solution. The quaternary phosphonium adsorbent (PS-TEP) prepared by the nucleophilic substitution reaction between triethyl phosphine with the smallest volume and chloromethylated polystyrene (PS-Cl) exhibited the best gold loading capacity (617.90 mg g-1). The adsorption mechanism of gold(III) on PS-TEP surface mainly involves anion exchange between AuCl4- and Cl- in the adsorbent. The charge level of the H atom closest to -CH2-P+ group directly determines the strength of the interaction between the adsorbent and the gold ion. Multiwfn and VMD programs visually confirm the weak interaction between PS-TEP+ and AuCl4-. After 5 adsorption-stripping cycles, the adsorption rate of gold(III) in solution remained at about 99 %. In addition, PS-TEP exhibited good gold(III) selectivity in both simulated and actual WPCBs gold leaching solutions. These results indicate that the large-particle PS-TEP with high capacity is suitable for selective gold recovery from WPCBs leaching solution.

Effectively adsorb Au(S2O3)23- using aminoguanidine as trapping group from thiosulfate solutions.

Thiosulfate gold leaching is one of the most promising green cyanide-free gold extraction processes; however, the difficulty of recovering Au(I) from the leaching system hinders its further development. This study prepared aminoguanidine-functionalized microspheres (AGMs) via a one-step reaction involving nucleophilic substitution between aminoguanidine hydrochloride and chloromethylated polystyrene microspheres and used AGMs to adsorb Au(I) from thiosulfate solutions. Scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to analyze the structure and properties of AGMs. Experiments were designed to investigate the effects of pH, temperature, initial Au(I), and thiosulfate concentrations on the gold adsorption performance of AGMs. Results demonstrated that AGMs can efficiently adsorb Au(I) from thiosulfate solutions in a wide pH range. The adsorption process conforms to the pseudo-second-order kinetic model and Langmuir isotherm model, with a maximum capacity of 22.03 kg/t. Acidic thiourea is an effective desorbent, and after four adsorption-desorption cycles, the adsorption rate of Au(I) by AGMs is 78.63%, which shows AGMs have good cyclic application potential. Based on the results of characterization, experiments, and density functional theory calculations, the mechanism for the adsorption of [Au(S2O3)2]3- on AGMs involves anion exchange. Importantly, AGMs exhibited satisfactory adsorption property for Au(I) in practical Cu2+-NH3(en)-S2O32- systems. This study provided experimental reference for the recovery of Au(I) from thiosulfate solution.

Highly Efficient Recovery of Au(I) from Gold Leaching Solution Using Sodium Dimethyldithiocarbamate.

As a sustainable, nontoxic and environmentally friendly cyanide-free gold leaching agent, thiosulfate has been applied to some extent in the field of hydrometallurgy. However, the difficult recovery of gold ions in gold leaching solutions limits further application of thiosulfate gold leaching technology. This study demonstrated the feasibility of gold recovery by sodium dimethyldithiocarbamate (SDD) precipitation and recycling of ammonia and a lixiviant in solution. SDD achieved the purpose of recovering gold by forming granular precipitates with gold ions in solution. It can almost completely recover gold ions in 2.5-17.34 mg/L of gold leaching solution within 1 min at 25 °C, in which a gold recovery capacity of 7.99 kg/t is achieved. The leaching rate of gold ore did not change significantly after recycling the residual ammonia and thiosulfate in the leaching solution after gold recovery by SDD, and its leaching rate basically remained at 81%. The mechanism of SDD recovering Au was determined to involve the ligand exchange of SDD- and Au[(S2O3)2]3-. Moreover, the interaction mechanism between SDD and Au(I) was further validated by density functional theory calculations. Considering its low cost, simple technology, and environmental friendliness, the SDD precipitation process has the potential for large-scale application in gold recovery from thiosulfate gold leaching solutions.

Synthesis of azole-functionalized microspheres and their adsorption properties for gold(I) thiosulfate complex.

Gold is an essential precious metal with exceptional properties. Thus, azole-functionalized microspheres (PS-3-AT) were prepared by grafting 3-amino-1,2,4-triazole (3-AT) into chloromethyl polystyrene beans (PS-Cl) and used as a novel adsorbent for the gold(I)-thiosulfate complex. The effects of initial gold concentration, thiosulfate concentration, temperature, and pH on the Au(S2O3)23- adsorption process over PS-3-AT were investigated. In this study, PS-3-AT was considered an effective adsorbent for Au(I) recovery from a thiosulfate solution, demonstrating that PS-3-AT completely adsorbed Au(S2O3)23- with an adsorption capacity of 39.8 kg t-1 achieved during multistage adsorption testing. Through adsorption kinetics and isotherm studies, the pseudo-second-order and Freundlich models well describe the adsorption process of PS-3-AT for Au(I), also suggesting the exothermic nature. Furthermore, SEM, FT-IR spectroscopy, BET, and XPS techniques were used to characterize the surface and structural properties of the samples. Notably, a reliable adsorption mechanism was developed that proposed the formation of the -NH+Cl- group during the grafting process and Cl- exchange with Au(S2O3)23- to achieve Au(I) capture. Moreover, quantum chemistry calculations and the independent gradient model (IGM) were adopted to visualize the interaction between PS-3-AT and Au(S2O3)23- at an atomic level. The desorption ratio was 97.9% while 2 M NaCl was used as the desorbent, and regeneration with PS-3-AT was achieved after five cycles. Therefore, the facile synthetic method and adsorption properties of PS-3-AT for the gold(I)-thiosulfate complex are satisfactory, which is valuable for the development of thiosulfate gold leaching technologies.

Review of microchip analytical methods for the determination of pathogenic Escherichia coli.

Bacterial infections remain the principal cause of mortality worldwide, making the detection of pathogenic bacteria highly important, especially Escherichia coli (E. coli). Current E. coli detection methods are labour-intensive, time-consuming, or require expensive instrumentation, making it critical to develop new strategies that are sensitive and specific. Microchips are an automated analytical technique used to analyse food based on their separation efficiency and low analyte consumption, which make them the preferred method to detect pathogenic bacteria. This review presents an overview of microchip-based analytical methods for analysing E. coli, which were published in recent years. Specifically, this review focuses on current research based on microchips for the detection of E. coli and reviews the limitations of microchip-based methods and future perspectives for the analysis of pathogenic bacteria.

Synthesis and evaluation of ion-imprinted composite membranes of Cr(vi) based on ß-diketone functional monomers.

Using Cr(vi) as the imprinted ions and 2-allyl-1,3-diphenyl-1,3-propanedione (ADPD) (a compound synthesized by independent design) as the functional monomer, a series of chromium ion-imprinted composite membranes (Cr(vi)-IICMs) and corresponding non-imprinted composite membranes (NICMs) were synthesized and tested. The results showed that the Cr(vi)-IICM10 membrane prepared under optimal experimental conditions exhibited a high adsorption capacity towards Cr(vi) (Q = 30.35 mg g-1) and a high imprinting factor (α = 2.70). The structural characteristics of Cr(vi)-IICM10 and NICM10 were investigated using FE-SEM, ATR-FTIR, and BET techniques combined with UV-Vis photometry and inductively coupled plasma emission spectrometry (ICP-OES) to evaluate the adsorption performance and permeation selectivity, while the effect on adsorption permeance of varying the experimental conditions including the solvent type, pH, and temperature was also investigated. The results showed that Cr(vi)-IICM10 is a mesoporous material with excellent permeation selectivity, reusability, and favorable pH response, and that its adsorption behavior is in accordance with the Langmuir model and pseudo-first-order kinetics. Thus, Cr(vi)-IICM10 shows great potential towards utilization as a "smart membrane" to control the separation and removal of Cr(vi) in wastewater, and also proved a reasonable design of the new functional monomer ADPD.

Investigation of hydroxypropyl-ß-cyclodextrin-based synergistic system with chiral nematic mesoporous silica as chiral stationary phase for enantiomeric separation in microchip electrophoresis.

The separation of chiral amino acids using microchip electrophoresis (MCE) was investigated using chiral nematic mesoporous silica (CNMS) as the chiral stationary phase, with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as the chiral selector. Individually, neither CNMS nor HP-ß-CD achieved separation, so they were combined. Ten chiral amino acids (phenylalanine, tryptophan, glutamic, alanine, serine, aspartic acid, cysteine, methionine, tyrosine, and histidine) were selected as the model analytes. Under optimized conditions, we achieved baseline separation of six chiral amino acids, and the other four chiral amino acids displayed improved resolution. These results indicate the presence of a synergistic effect between CNMS and HP-ß-CD, showing that the combination of a chiral stationary phase and a chiral additive is a promising approach for enantioseparation using MCE.

Physician preferences for chemotherapy in the treatment of non-small cell lung cancer in China: evidence from multicentre discrete choice experiments.

OBJECTIVE: To evaluate physician risk-benefit preferences and trade-offs when making chemotherapy decisions for patients with non-small cell lung cancer (NSCLC). DESIGN: A discrete choice experiment (DCE). SETTINGS: Tertiary hospitals in Beijing, Shanghai, Guangzhou and Chengdu of China. PARTICIPANTS: The participants were 184 physicians (mean age of 37 years) with more than 1 year of NSCLC chemotherapy practice. OUTCOMES: The DCE survey was constructed by six attributes: progression-free survival (PFS), disease control rate (DCR), risk of moderate side effects, risk of severe side effects, mode of administration and out-of-pocket costs. Physicians' relative preferences and trade-offs in patient out-of-pocket costs for each attribute level were estimated using a mixed logit model, and interaction terms were added to the model to assess preferences variation among physicians with different sociodemographic factors. RESULTS: Physicians had the strongest preferences for improvements in PFS, followed by reducing the risk of severe side effects. The DCR, risk of moderate side effects and mode of administration were ranked in decreasing order of importance. There was little variation in preferences among physicians with different sociodemographic characteristics. Physicians were willing to trade $4814 (95% CI $4149 to $5480) of patient out-of-pocket costs per month for a chemotherapy that guaranteed 11 months of PFS, followed by $1908 (95% CI $1227 to $2539) for reducing the risk of severe side effects to 2%. CONCLUSIONS: With regard to chemotherapy for patients with NSCLC, prolonging PFS, reducing severe and moderate side effects were primary considerations for physicians in China. The mode of administration and treatment costs significantly influenced physicians' therapeutic decision. The current findings could add some evidence to inform NSCLC chemotherapy implementation and promote shared decision-making.

Patient Preferences For Chemotherapy In The Treatment Of Non-Small Cell Lung Cancer: A Multicenter Discrete Choice Experiment (DCE) Study In China.

OBJECTIVE: The study aims to quantify patients' risk-benefit preferences for chemotherapy in the treatment of non-small cell lung cancer (NSCLC), and to elicit their willingness to pay (WTP) for treatment outcomes. METHODS: A face-to-face discrete choice experiment (DCE) was conducted on NSCLC patients in four tertiary hospitals each from Beijing, Shanghai, Guangzhou and Chengdu in China. Patients were invited to complete choice questions that constructed by seven attributes: progression-free survival (PFS), disease control rate (DCR), rash, nausea and vomiting, tiredness, mode of administration and out-of-pocket costs. A mixed logit model was used to evaluate the choice model. Estimates of relative preferences and marginal willingness to pay for each attribute were then explored. RESULTS: A total of 361 patients completed the survey. Improvements in PFS (10, 95% CI: 8.4-11.6) were the most important attribute for patients, followed by increase in DCR (4.6, 95% CI: 3.4-5.8). Tiredness (3.9, 95% CI: 2.9-5.1) was judged to be the most important risk. While remaining attributes were ranked in decreasing order of importance: nausea and vomiting (1.9, 95% CI: 0.9-3.0), mode of administration (0.8, 95% CI: 0.2-1.4) and rash (0.5, 95% CI: -0.6-1.5). There was little variation in preferences among patients with different sociodemographic characteristics. Patients were monthly willing to pay $2304 (95% CI, $1916-$2754) that guaranteed 11 months of PFS, followed by $1465 (95% CI, $1163-$1767) per month to improve their disease control rate by 90%. CONCLUSION: The results suggested that efficacy was the most important attribute for patients. Side effects, mode of administration and treatment cost significantly influenced patient preferences. Patient engagement in prioritizing their treatment preferences should be emphasized during the clinical decision-making process and regimen implementation.

Sensitive assay of Escherichia coli in food samples by microchip capillary electrophoresis based on specific aptamer binding strategy.

The rapid and cost-effective detection of bacteria is of great importance to ensuring food safety, preventing food poisoning. Herein, we developed a sensitive detection of Escherichia coli (E. coli) using bacteria-specific aptamer in conjunction with microchip capillary electrophoresis-coupled laser-induced fluorescence (MCE-LIF). Based on the differences between charge to mass ratios of free aptamer and bacteria-aptamer complex, which influence their electrophoretic mobilities, the separation of free aptamers and complex peaks by MCE could be achieved. Under optimal conditions, the sensitive detection of E. coli was achieved with a detection limit of 3.7 × 102 CFU mL-1, at a fast response of 135 s and a short detection length of 2.3 cm. The spiked recovery experiment showed that E. coli could be recovered from spiked drinking water and milk samples with recovery rates of 94.7% and 92.8%, respectively. This work demonstrates that the established detection strategy can be a useful tool for the detection and/or monitoring of E. coli in food and environment.

Supramolecularly imprinted polymeric solid phase microextraction coatings for synergetic recognition nitrophenols and bisphenol A.

We herein firstly presented supramolecularly imprinted polymeric (SMIP) solid phase microextraction (SPME) coatings which showed synergetic recognition for nitrophenols and bisphenol A. A series of ß-cyclodextrins (ß-CD) with different substituents were successfully designed and synthesized. It was employed as supramolecular functional monomers for SMIPs. The orderly assembling structures settled down under the molecular imprinting process. The four of SMIPs solid phase microextraction coatings showed good selectivity for the template and could be used to extract 4-NP in real water samples. Furthermore, the inclusion effects of derived ß-CDs with the 4-NP were investigated by measuring the UV-vis spectra and the theoretical calculations. The strongest intermolecular force is come from the supramolecular complex of 4-NP and ß-CD-4 which shows the strongest UV-vis spectra absorption value. Meanwhile, the difference of the theoretical calculations value coming from the system of derived ß-CDs and 4-NP is the largest, revealing the strongest electronic interactions between derived ß-CD-4 and 4-NP. Therefore, these polymers possess inclusion interactions from ß-cyclodextrin cavities and hydrogen-bonding interactions from molecular imprinting. Multiple adsorptions triggered off a synergetic recognition for target analytes. The SMIPs also performed highly selective recognition in complex real water sample with sensitive detection limits.

Sparse-Aware Bias-Compensated Adaptive Filtering Algorithms Using the Maximum Correntropy Criterion for Sparse System Identification with Noisy Input.

To address the sparse system identification problem under noisy input and non-Gaussian output measurement noise, two novel types of sparse bias-compensated normalized maximum correntropy criterion algorithms are developed, which are capable of eliminating the impact of non-Gaussian measurement noise and noisy input. The first is developed by using the correntropy-induced metric as the sparsity penalty constraint, which is a smoothed approximation of the ℓ 0 norm. The second is designed using the proportionate update scheme, which facilitates the close tracking of system parameter change. Simulation results confirm that the proposed algorithms can effectively improve the identification performance compared with other algorithms presented in the literature for the sparse system identification problem.

ß-Cyclodextrin molecularly imprinted solid-phase microextraction coatings for selective recognition of polychlorophenols in water samples.

A series of ß-cyclodextrin derivatives were designed and synthesized. The derivatives were investigated as functional monomers in molecularly imprinted polymeric solid-phase microextraction (MIP-SPME) fiber coatings. The coatings, with a layer thickness of 250 µm, were immobilized onto stainless steel using a capillary tube as a mold. This study employed a simple, easy, and reproducible method to prepare uniform coatings for polychlorophenols extraction. The combination of molecular inclusion effects and the molecular imprinting sites was expected to enhance the molecular recognition ability for polychlorophenols. Compared with non-imprinted polymer coatings and MIP coatings with methacrylic acid as the functional monomer, the ß-cyclodextrin MIP-SPME coatings exhibited significantly higher extraction amounts and excellent selectivity to the template of triclosan. The MIP-SPME coatings exhibited a favorable synergistic extraction capacity resulting from the ß-cyclodextrin cavity and molecularly imprinted binding sites. The method of ß-cyclodextrin MIP-SPME coupled with high performance liquid chromatography (HPLC) for triclosan and polychlorophenols analysis in real water samples was developed. The limit of quantification was 1 µg/L for the three polychlorophenols. The recovery for three analytes ranged from 83.71% to 109.98%, with the relative standard deviation (RSD) of 2.83% to 12.19%. The ß-cyclodextrin MIP-SPME fiber coatings could be used for at least 100 cycles. Graphical Abstract Synergistic effects in ß-cyclodextrin MIP-SPME.