Enhanced antigen-specific CD8 T cells contribute to early protection against FMDV through swine DC vaccination.

Foot-and-mouth disease virus (FMDV) remains a challenge for cloven-hooved animals. The currently licensed FMDV vaccines induce neutralizing antibody (NAb)-mediated protection but show defects in the early protection. Dendritic cell (DC) vaccines have shown great potency in inducing rapid T-cell immunity in humans and mice. Whether DC vaccination could enhance early protection against FMDV has not been elaborately explored in domestic pigs. In this study, we employed DC vaccination as an experimental approach to study the roles of cellular immunity in the early protection against FMDV in pigs. Autologous DCs were differentiated from the periphery blood mononuclear cells of each pig, pulsed with inactivated FMDV (iFMDV-DC) and treated with LPS, and then injected into the original pigs. The cellular immune responses and protective efficacy elicited by the iFMDV-DC were examined by multicolor flow cytometry and tested by FMDV challenge. The results showed that autologous iFMDV-DC immunization induced predominantly FMDV-specific IFN-γ-producing CD4+ T cells and cytotoxic CD8+ T cells (CTLs), high NAb titers, compared to the inactivated FMDV vaccine, and accelerated the development of memory CD4 and CD8 T cells, which was concomitantly associated with early protection against FMDV virulent strain in pigs. Such early protection was associated with the rapid proliferation of secondary T-cell response after challenge and significantly contributed by secondary CD8 effector memory T cells. These results demonstrated that rapid induction of cellular immunity through DC immunization is important for improving early protection against FMDV. Enhancing cytotoxic CD8+ T cells may facilitate the development of more effective FMDV vaccines.IMPORTANCEAlthough the currently licensed FMDV vaccines provide NAb-mediated protection, they have defects in early immune protection, especially in pigs. In this study, we demonstrated that autologous swine DC immunization augmented the cellular immune response and induced an early protective response against FMDV in pigs. This approach induced predominantly FMDV-specific IFN-γ-producing CD4+ T cells and cytotoxic CD8+ T cells, high NAb titers, and rapid development of memory CD4 and CD8 T cells. Importantly, the early protection conferred by this DC immunization is more associated with secondary CD8+ T response rather than NAbs. Our findings highlighted the importance of enhancing cytotoxic CD8+ T cells in early protection to FMDV in addition to Th1 response and identifying a strategy or adjuvant comparable to the DC vaccine might be a future direction for improving the current FMDV vaccines.

GTPase activity of porcine Mx1 plays a dominant role in inhibiting the N-Nsp9 interaction and thus inhibiting PRRSV replication.

Porcine Mx1 is a type of interferon-induced GTPase that inhibits the replication of certain RNA viruses. However, the antiviral effects and the underlying mechanism of porcine Mx1 for porcine reproductive and respiratory syndrome virus (PRRSV) remain unknown. In this study, we demonstrated that porcine Mx1 could significantly inhibit PRRSV replication in MARC-145 cells. By Mx1 segment analysis, it was indicated that the GTPase domain (68-341aa) was the functional area to inhibit PRRSV replication and that Mx1 interacted with the PRRSV-N protein through the GTPase domain (68-341aa) in the cytoplasm. Amino acid residues K295 and K299 in the G domain of Mx1 were the key sites for Mx1-N interaction while mutant proteins Mx1(K295A) and Mx1(K299A) still partially inhibited PRRSV replication. Furthermore, we found that the GTPase activity of Mx1 was dominant for Mx1 to inhibit PRRSV replication but was not essential for Mx1-N interaction. Finally, mechanistic studies demonstrated that the GTPase activity of Mx1 played a dominant role in inhibiting the N-Nsp9 interaction and that the interaction between Mx1 and N partially inhibited the N-Nsp9 interaction. We propose that the complete anti-PRRSV mechanism of porcine Mx1 contains a two-step process: Mx1 binds to the PRRSV-N protein and subsequently disrupts the N-Nsp9 interaction by a process requiring the GTPase activity of Mx1. Taken together, the results of our experiments describe for the first time a novel mechanism by which porcine Mx1 evolves to inhibit PRRSV replication. IMPORTANCE: Mx1 protein is a key mediator of the interferon-induced antiviral response against a wide range of viruses. How porcine Mx1 affects the replication of porcine reproductive and respiratory syndrome virus (PRRSV) and its biological function has not been studied. Here, we show that Mx1 protein inhibits PRRSV replication by interfering with N-Nsp9 interaction. Furthermore, the GTPase activity of porcine Mx1 plays a dominant role and the Mx1-N interaction plays an assistant role in this interference process. This study uncovers a novel mechanism evolved by porcine Mx1 to exert anti-PRRSV activities.

A Systematic Review and Meta-analysis of Renin-angiotensin System Inhibitors and Angiotensin Receptor Neprilysin Inhibitors in Preventing Recurrence After Atrial Fibrillation Ablation.

ABSTRACT: To systematically evaluate the efficacy and safety of renin-angiotensin system inhibitors (RASIs) and angiotensin receptor neprilysin inhibitors in preventing the recurrence of atrial fibrillation after atrial fibrillation ablation, we have written this meta-analysis. We systematically searched randomized controlled trials or cohort studies on RASIs and angiotensin receptor neprilysin inhibitor-sacubitril/valsartan (SV) in preventing the recurrence of atrial fibrillation. Two researchers independently screened the literature, extracted the data, and assessed the risk of bias in the included studies. Afterward, the meta-analysis was performed using RevMan 5.3 software. This meta-analysis results showed that the recurrence rate of atrial fibrillation after ablation in subjects using RASIs was lower than that in subjects not using them [relative risk = 0.85, 95% confidence interval (CI) (0.72-0.99), P = 0.03]; the recurrence rate in subjects using SV was lower than that in subjects using RASIs [RR= 0.50, 95% CI (0.37-0.68), P < 0.00001]. These results show that both the use of RASIs and SV can prevent the recurrence of after atrial fibrillation ablation, among which the use of SV is more effective.

Electrochemical Radical Tandem Difluoroethylation/Cyclization of Unsaturated Amides to Access MeCF2-Featured Indolo/Benzoimidazo [2,1-a]Isoquinolin-6(5H)-ones.

A metal-free electrochemical oxidative difluoroethylation of 2-arylbenzimidazoles was accomplished, which provided an efficient strategy for the synthesis of MeCF2-containing benzo[4,5]imidazo[2,1-a]-isoquinolin-6(5H)-ones. In addition, the method also enabled the efficient construction of various difluoroethylated indolo[2,1-a]isoquinolin-6(5H)-ones. Notably, this electrochemical synthesis protocol proceeded well under mild conditions without metal catalysts or exogenous additives/oxidants added.

A potent CD8 T-cell response may be associated with partial cross-protection conferred by an attenuated Chinese HP-PRRSV vaccine against NADC30-like PRRSV challenge.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most devastating pathogens to the global swine industry. Many commercial PRRSV vaccines, originally designed to provide homologous protection, have shown partial protection against heterologous strains. However, the protective immune mechanisms mediated by these PRRSV vaccines are not fully understood. In this study, we investigated the factors responsible for partial protection conferred by an attenuated Chinese HP-PRRSV vaccine (TJM-F92) against heterologous NADC30-like PRRSV. By analysing peripheral T-cell responses induced by the TJM-F92 vaccine and local and systemic memory responses following challenge with NADC30-like PRRSV (SD17-38 strains) as well as neutralizing antibody response, we found that the TJM-F92 vaccine induced a significant expansion of CD8 T cells but not CD4 T cells or γδ T cells. The expanded CD8 T cells exhibited a phenotype of effector memory T cells and secreted IFN-γ upon restimulation with SD17-38 strains in vitro. In addition, only CD8 T cells in the prior immunized pigs rapidly expanded in the blood and spleen after heterologous challenge, with higher magnitude, compared to the unvaccinated pigs, showing a remarkable memory response. In contrast, no obvious humoral immune response was enhanced in the vaccinated and challenged pigs, and no heterologous neutralizing antibodies were detected throughout the experiment. Our results suggested that CD8 T cells elicited by the TJM-F92 vaccine may be responsible for partial heterologous protection against NADC30-like PRRSV strains and potentially recognize the conserved antigens among PRRSV strains.

Metal-Free Electrochemical Oxidative Difluoroethylation/Cyclization of Olefinic Amides To Construct Difluoroethylated Azaheterocycles.

A new strategy of electrochemical oxidative difluoroethylation to generate difluoroethyl radical with sodium difluoroethylsulfinate (DFES-Na) has been reported for the first time. The method allows quick access to a variety of valuable difluoroethylated azaheterocycles including oxindoles and isoquinoline-1,3-diones via radical tandem difluoroethylation/cyclization in moderate to good yields. The electrochemical cyclopropyldifluoromethylation of N-arylacrylamides also works well using this strategy. Moreover, radical capture and cyclic voltammetry (CV) experiments are also carried out to determine the proposed mechanism.

Photopromoted Free Radical Silylation of 2-Aryl-2H-indazoles with Silanes.

Photoinduced silylation of silanes with 2-aryl-2H-indazoles was developed under mild conditions, which could efficiently result in diverse 3-silylated 2H-indazoles with good substrate scopes. A series of scaled-up to gram level and radical capture operations were performed in this system. Meanwhile, a bioactive molecule was tolerated well under typical conditions.

Effects of Radiation-Induced Skin Injury on Hyaluronan Degradation and Its Underlying Mechanisms.

Radiation-induced skin injury (RISI) is a frequent and severe complication with a complex pathogenesis that often occurs during radiation therapy, nuclear incidents, and nuclear war, for which there is no effective treatment. Hyaluronan (HA) plays an overwhelming role in the skin, and it has been shown that UVB irradiation induces increased HA expression. Nevertheless, to the best of our knowledge, there has been no study regarding the biological correlation between RISI and HA degradation and its underlying mechanisms. Therefore, in our study, we investigated low-molecular-weight HA content using an enzyme-linked immunosorbent assay and changes in the expression of HA-related metabolic enzymes using real-time quantitative polymerase chain reaction and a Western blotting assay. The oxidative stress level of the RISI model was assessed using sodium dismutase, malondialdehyde, and reactive oxygen species assays. We demonstrated that low-molecular-weight HA content was significantly upregulated in skin tissues during the late phase of irradiation exposure in the RISI model and that HA-related metabolic enzymes, oxidative stress levels, the MEK5/ERK5 pathway, and inflammatory factors were consistent with changes in low-molecular-weight HA content. These findings prove that HA degradation is biologically relevant to RISI development and that the HA degradation mechanisms are related to HA-related metabolic enzymes, oxidative stress, and inflammatory factors. The MEK5/ERK5 pathway represents a potential mechanism of HA degradation. In conclusion, we aimed to investigate changes in HA content and preliminarily investigate the HA degradation mechanism in a RISI model under γ-ray irradiation, to consider HA as a new target for RISI and provide ideas for novel drug development.

Comparative assessment of efficacy and safety of approved oral therapies for overactive bladder: a systematic review and network meta-analysis.

bladder based on a systematic review and network meta-analysis approach. METHODS: Pubmed, Embase, Web of Science, and the Cochrane Register of Clinical Trials databases were systematically searched. The search time frame was from database creation to June 2, 2022. Randomized controlled double-blind trials of oral medication for overactive bladder were screened against the protocol's entry criteria. Trials were evaluated for quality using the Cochrane Risk of Bias Assessment Tool, and data were statistically analyzed using Stata 16.0 software. RESULT: A total of 60 randomized controlled double-blind clinical trials were included involving 50,333 subjects. Solifenacin 10mg was the most effective in mean daily micturitions and incontinence episodes, solifenacin 5/10mg in mean daily urinary urgency episodes and nocturia episodes, fesoterodine 8mg in urgency incontinence episodes/d and oxybutynin 5mg in voided volume/micturition. In terms of safety, solifenacin 5mg, ER-tolterodine 4mg, mirabegron, vibegron and ER-oxybutynin 10mg all showed a better incidence of dry mouth, fesoterodine 4mg, ER-oxybutynin 10mg, tolterodine 2mg, and vibegron in the incidence of constipation. Compared to placebo, imidafenacin 0.1mg showed a significantly increased incidence in hypertension, solifenacin 10mg in urinary tract infection, fesoterodine 4/8mg and darifenacin 15mg in headache. CONCLUSION: Solifenacin showed better efficacy. For safety, most anticholinergic drugs were more likely to cause dry mouth and constipation, lower doses were better tolerated. The choice of drugs should be tailored to the patient's specific situation to find the best balance between efficacy and safety.

Headspace Solid-Phase Microextraction Following Chemical Vapor Generation for Ultrasensitive, Matrix Effect-Free Detection of Nitrite by Microplasma Optical Emission Spectrometry.

A new chemical vapor generation method coupled with headspace solid-phase microextraction miniaturized point discharge optical emission spectrometry (HS-SPME-µPD-OES) for the sensitive and matrix effect-free detection of nitrite in complex samples is described. In an acidic medium, the volatile cyclohexene was generated from cyclamate in the presence of nitrite, which was volatilized to the headspace of the container, efficiently separated, and preconcentrated by HS-SPME. Consequently, the SPME fiber was transferred to a laboratory-constructed thermal desorption chamber wherein the cyclohexene was thermally desorbed and swept into µPD-OES for its sensitive quantification via monitoring the carbon atomic emission line at 193.0 nm. As a result, the quantification of nitrite was accomplished through the determination of cyclohexene. The application of HS-SPME as a sampling technique not only simplifies the experimental setup of µPD-OES but it also preconcentrates and separates cyclohexene from N2 and sample matrices, thus eliminating the interference from water vapor and N2 and significantly improving the analytical performance on the determination of nitrite. Under the optimum experimental conditions, a limit of detection of 0.1 µg L-1 was obtained, which is much better than that obtained by conventional methods. The precision, expressed as relative standard deviation, was better than 3.0% at a concentration of 10 µg L-1. The proposed method provides several advantages of portability, simplicity, high sensitivity, and low energy consumption and eliminates expensive instruments and matrix interference, thus retaining a promising potential for the rapid, sensitive, and field analysis of nitrite in various samples.

Probing the Formation Kinetics and Thermodynamics with Rationally Designed Analytical Tools Enables One-Pot Synthesis and Purification of a Tetrahedral DNA Nanostructure.

The development of robust analytical tools capable of probing the formation kinetics and thermodynamics of DNA nanostructures is a crucial step toward better understanding and manufacturing of diverse DNA-based materials. Herein, we introduce a real-time fluorescence anisotropy assay and rationally designed DNA reaction termination probes (DRTPs) as a set of new tools for exploring the formation mechanisms of DNA nanostructures. We deployed these tools for probing the formation of a classic tetrahedral DNA nanostructure (TDN) as a model system. Our tools revealed that the formation of TDN was dominated by simultaneous hybridization, whereas its undesired side products were caused mainly through step-wise hybridization. An optimal reaction temperature exists that favors the formation of TDN over side products. With insight into the TDN formation mechanism, we further engineered magnetic DRTPs to achieve single-step purification of TDN, enabling 10-fold improvement in the ratio between the targeted TDN and undesired side products without tedious procedures or bulky instruments. Combining the optimal reaction and purification conditions, we finally demonstrated the one-pot synthesis and purification of TDN. The analytical techniques offered in this work may hold potential to find wide applications and inspire new analytical methods for structural DNA nanotechnology.

Chimeric HP-PRRSV2 containing an ORF2-6 consensus sequence induces antibodies with broadly neutralizing activity and confers cross protection against virulent NADC30-like isolate.

Due to the substantial genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV), commercial PRRS vaccines fail to provide sufficient cross protection. Previous studies have confirmed the existence of PRRSV broadly neutralizing antibodies (bnAbs). However, bnAbs are rarely induced by either natural infection or vaccination. In this study, we designed and synthesized a consensus sequence of PRRSV2 ORF2-6 genes (ORF2-6-CON) encoding all envelope proteins based on 30 representative Chinese PRRSV isolates. The ORF2-6-CON sequence shared > 90% nucleotide identities to all four lineages of PRRSV2 isolates in China. A chimeric virus (rJS-ORF2-6-CON) containing the ORF2-6-CON was generated using the avirulent HP-PRRSV2 JSTZ1712-12 infectious clone as a backbone. The rJS-ORF2-6-CON has similar replication efficiency as the backbone virus in vitro. Furthermore, pig inoculation and challenge studies showed that rJS-ORF2-6-CON is not pathogenic to piglets and confers better cross protection against the virulent NADC30-like isolate than a commercial HP-PRRS modified live virus (MLV) vaccine. Noticeably, the rJS-ORF2-6-CON strain could induce bnAbs while the MLV strain only induced homologous nAbs. In addition, the lineages of VDJ repertoires potentially associated with distinct nAbs were also characterized. Overall, our results demonstrate that rJS-ORF2-6-CON is a promising candidate for the development of a PRRS genetic engineered vaccine conferring cross protection.

Simple Universal Strategy for Quantification of Carboxyl Groups on Carbon Nanomaterials: Carbon Dioxide Vapor Generation Coupled to Microplasma for Optical Emission Spectrometric Detection.

The physicochemical properties and applications of carbon nanomaterials are remarkably dependent on the amount of carboxyl group on their surfaces. Unfortunately, it is challenging to determine the carboxyl group on carbon nanomaterials at an ultralow density not only due to the low sensitivities of conventional techniques, but also because there are no matrix-matched certified reference materials available. In this work, a novel strategy comprising coupling carbon dioxide vapor generation to a microplasma optical emission spectrometer was developed for the sensitive and accurate quantification of surface carboxyl groups on carbon nanomaterials. The carboxyl group on multiwall carbon nanotubes (MWCNTs), graphene (G), or its oxide (GO) was converted to carboxylic acid using concentrated hydrochloric acid prior to quantification. The generated carboxylic acid was purified and then reacted with sodium bicarbonate to generate CO2, which was swept into a miniaturized point discharge optical emission spectrometer (µPD-OES) for the detection of carbon atomic emission lines. Potassium hydrogen phthalate (KHP) served as a calibration standard for quantification of the carboxyl group on G/GO/MWCNTs, thus, overcoming the lack of CRMs. Owing to the high sensitivity of µPD-OES for the detection of CO2, a limit of detection of 0.1 µmol g-1 (1 nmol) was obtained for the carboxyl group based on a sample mass of 10 mg G/GO/MWCNTs, superior to that obtained using conventional methods. Moreover, the proposed method not only retains several unique advantages of good accuracy and elimination of the use of complicated, expensive, and high power-consumption instruments, but was also applicable to the quantification of the carboxyl group on other nanomaterials such as carboxylated magnetic microspheres.

Integration of Flow Injection Capillary Liquid Electrode Discharge Optical Emission Spectrometry and Microplasma-Induced Vapor Generation: A System for Detection of Ultratrace Hg and Cd in a Single Drop of Human Whole Blood.

A simple and miniature analytical system was developed to determine Hg and Cd in small amounts of samples by integrating flow injection capillary liquid electrode discharge (CLED) optical emission spectrometry (OES) and microplasma-induced vapor generation (PIVG) atomic fluorescence spectrometry (AFS). With the assistance of the inherent capillary driving force and the force arising from the solution vaporization in the microplasma, the sample solution was automatically transported into the discharge chamber wherein analytes were simultaneously excited to generate their atomic emission lines and converted to their volatile species. Subsequently, the volatile species were further swept into AFS for their further determination. Therefore, the same sample could be successively analyzed by OES and AFS. Owing to the unique independent linear-range and sensitivity of CLED-OES and PIVG-AFS, the developed system not only significantly extended its linear range to 6 orders of magnitude but also remarkably reduced the sample consumption to several microliters. Thus, wide linear-range and ultrasensitive determination of Hg and Cd in limited amounts of samples were accomplished simply by sharing one single capillary liquid electrode discharge source. Under the optimized conditions, limits of detection (LODs) of 10 µg L-1 were obtained for both Hg and Cd when CLED-OES was used as a detector, whereas the LODs for Hg and Cd were improved to 0.03 µg L-1 and 0.04 µg L-1 with AFS detector, respectively. In addition, the extremely wide linear-range of 0.001-100 mg L-1 and 0.001-40 mg L-1 were obtained for Hg and Cd, respectively. The potential application of this method was validated by successfully analyzing three Certified Reference Materials (ZK021-1, GBW(E)090033, and GBW(E)090034) and six human blood samples.

Visible-light-induced radical trifluoromethylthiolation of N-(o-cyanobiaryl)acrylamides.

An efficient and general visible-light-mediated trifluoromethylthiolation of N-(o-cyanobiaryl)acrylamides has been successfully accomplished using N-trifluoromethylthiosaccharin as an effective source of SCF3 radicals. The reaction was proposed to proceed via a domino radical trifluoromethylthiolation/cyano insertion/cyclization to afford the corresponding SCF3-containing ring-fused phenanthridine derivatives in moderate to good yields.

Point Discharge Optical Emission Spectrometer as a Gas Chromatography (GC) Detector for Speciation Analysis of Mercury in Human Hair.

Speciation analysis of mercury in hair facilitates accurate evaluation of mercury exposure to humans and insights into the intertransformation of different mercury species in the human body. However, conventional hyphenated techniques used for mercury speciation analysis usually require expensive instruments and a complex interface. In this work, a compact and miniaturized point discharge (PD) atomic emission spectrometer was utilized as a detector of gas chromatography for the speciation analysis of mercury. Mercury species extracted from hair were derivatized to their volatile species with NaBEt4 and subsequently preconcentrated by headspace solid-phase microextraction (HS-SPME) prior to their speciation analysis. Under the optimized conditions, limits of detection of 0.35 µg kg-1 (0.035 ng) and 1.0 µg kg-1 (0.10 ng) were obtained for IHg and MeHg, respectively, with a relative standard deviation (RSD) of better than 3.5%. Because of the compact and miniature conformation, high excitation capability, low power consumption of PD-OES, and efficient preconcentration of mercury species by HS-SPME, the proposed system not only overcomes the shortcomings associated with the conventional hyphenated techniques but also provides several unique advantages, including significant simplification of experimental setup, reduction of dead volume, and improvement of sensitivity. The accuracy of this system was validated by speciation analysis of mercury in a Certified Reference Material (GBW09101b, human hair) and 10 human hair samples collected from different people in the population.

Low-Temperature and Atmospheric Pressure Sample Digestion Using Dielectric Barrier Discharge.

A new sample digestion method using a double layer and coaxial dielectric barrier discharge (DBD) digestion reactor was developed for the sensitive determination of trace elements in rice samples. All the operation parameters of the DBD microplasma and other digestion conditions were carefully optimized. Three DBD-digestion modes were investigated for real matrix samples, including H2O-DBD-digestion, H2O2-DBD-digestion, and HNO3-DBD-digestion systems. Among the three modes, the H2O-DBD-digestion system provides a suitable digestion of sample without any additional chemicals, achieving environmental friendly sample treatment and eliminating the potential interferences. Under the optimized conditions, limits of detection for Mg, Mn, Zn, Cd, Cr, Co, and As were in the range of 0.01-0.35 ng g-1 by inductively coupled plasma mass spectrometry (ICPMS). The accuracy of the proposed method was checked by analysis of a certified reference material (GBW10043) and spiked samples with satisfactory results (83-113% recoveries).

Single-Drop Solution Electrode Discharge-Induced Cold Vapor Generation Coupling to Matrix Solid-Phase Dispersion: A Robust Approach for Sensitive Quantification of Total Mercury Distribution in Fish.

Sensitive quantification of mercury distribution in fish is challenging because of insufficient sensitivities of conventional analytical methods, the limited mass of organs (tens of micrograms to several milligrams), and dilution of analyte concentration from sample digestion. In this work, a simple and robust approach coupling multiwall carbon nanotubes assisted matrix solid-phase dispersion (MWCNTs-MSPD) to single-drop solution electrode glow discharge-induced cold vapor generation (SD-SEGD-CVG) was developed for the sensitive determination of mercury in limited amount of sample. Mercury species contained in a limited amount of sample can be efficiently extracted into a 100 µL of eluent by MWCNTs-MSPD, which are conveniently converted to Hg0 by SD-SEGD-CVG and further transported to atomic fluorescence spectrometry for their determination. Therefore, analyte dilution resulted from sample preparation is avoided and sensitivity is significantly improved. On the basis of consumption of 1 mg of sample, a limit of detection of 0.01 µg L-1 (0.2 pg) was obtained with relative standard deviations (RSDs) of 5.2% and 4.6% for 2 and 20 µg L-1, respectively. The accuracy of the proposed method was validated by analysis of three Certified Reference Materials with satisfying results. To confirm that SD-SEGD-CVG-AFS coupling to MWCNTs-MSPD is a promising method to quantify mercury distribution in fish, this method was successfully applied for the sensitive determination of mercury in seven organs of common carps (muscle, gill, intestine, liver, gallbladder, brain, and eye) after dietary of mercury species. The proposed method provides advantages of minimum sample dilution, low blank, high sample introduction efficiency, high sensitivity, and minimum toxic chemicals and sample consumption.

Pump- and Valve-Free Flow Injection Capillary Liquid Electrode Discharge Optical Emission Spectrometry Coupled to a Droplet Array Platform.

A miniature (2.5 cm length × 2.0 cm width × 1.0 cm height), low power (<10 W), and capillary liquid electrode microplasma optical emission spectrometer was developed for rapid determination of metallic species in aqueous solutions. The sample solution can be automatically introduced into the source without a pump owing to the inherent capillary attraction and the force arising from the solution vaporization induced by microplasma. A droplet array was used as a sampling platform to realize flow injection without using any valve and pump, significantly increasing throughput to 90 samples h-1. Sample volume is controlled through the sampling time and reduced to the nanoliter level. With a sampling time of 10 s (equal to 600 nL), detection limits of 30 µg L-1 (18 pg) and 75 µg L-1 (45 pg) were obtained for Cd and Hg, respectively, comparable to those reported for liquid electrode microplasma optical emission spectrometry. However, sample consumption is reduced more than 100-fold, making the proposed technique more suitable for the analysis of elements such as Cd, Hg, Li, Na, and K when sample volumes may be limited. The utility of this system was demonstrated by the determination of Cd and Hg in blood, real water samples, and Certified Reference Materials (rice powder, GBW07601a, and lobster hepatopancreas, TORT-3).

Continuous and Inexpensive Monitoring of Nonpurgeable Organic Carbon by Coupling High-Efficiency Photo-oxidation Vapor Generation with Miniaturized Point-Discharge Optical Emission Spectrometry.

Currently, no applicable analyzers are available to accomplish online continuous monitoring of organic pollution, which is one of the most important factors contributing to water shortages around the world, particularly in developing countries. In this work, a sensitive, miniaturized, inexpensive, and online nonpurgeable organic carbon (NPOC) analysis system was developed for continuous monitoring of such organic pollution. This system consists of a specially designed high-efficiency UV photo-oxidation vapor generation (HE-POVG) reactor and a miniaturized, low-power (7 W) point-discharge microplasma optical emission spectrometer (PD-OES). Organics present in sample or standard solutions are pumped to the HE-POVG and efficiently converted into CO2, which is separated and further transported to the PD-OES for NPOC analysis via highly sensitive detection of carbon atomic emission at 193.0 nm. Under optimal conditions, a limit of detection of 0.05 mg·L-1 (as C) is obtained, with precision better than 5.0% (relative standard deviation) at 5 mg·L-1. This system overcomes many shortcomings associated with conventional chemical oxygen demand or total organic carbon analyzers such as long analysis time, use of expensive and toxic chemicals, production of secondary toxic waste, requirement of large, power consuming and expensive instrumentation and difficulties implementing continuous online monitoring. The system was successfully applied to sensitive and accurate determination of NPOC in various water samples and for continuous monitoring of such organic pollution in tap water.