Colorimetric detection of alkaline phosphatase based on the off-on effect of light-responsive oxidase mimicking activity of covalent organic framework (Cu-TpBpy-COF) under near-neutral condition.

A colorimetric strategy has been developed for the detection of alkaline phosphatase (ALP) activity based on the off-on effect of the catalytic activity of light-responsive oxidase mimics covalent organic framework (Cu-TpBpy-COF) in near-neutral condition. Cu-TpBpy-COF can effectively catalyze the oxidation of the colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) by oxygen to form a blue oxidized product (oxTMB) with an absorption peak at 652 nm. Cu2+ is the active center of Cu-TpBpy-COF and pyrophosphate (PPi) can form a complex with Cu2+ to weaken the catalytic activity of Cu-TpBpy-COF. In the presence of ALP, PPi is hydrolyzed into orthophosphates (Pi) with low affinity to Cu2+, thus resulting in absorbance restoration. The absorbance at 652 nm is related to ALP activity in the linear range 10-150 U·L-1 with a detection limit of 7.17 U·L-1. The recoveries of ALP in serum samples are in the range 94.7~107.0% with relative standard deviations (RSD) lower than 5%. The decisive role of Cu2+ on the enhancing catalytic activities of Cu-TpBpy-COF in neutral condition was verified by TpBpy-COF and TpBD-COF as controls, in which the main difference between them is that TpBpy-COF contains pyridine nitrogen. Upon Cu2+ modification, Cu-TpBpy-COF has better catalytic activity than TpBpy-COF in a broader pH range because of the in situ generation of Cu+ under irradiation.

In situ growth of imine-based covalent organic framework as stationary phase for open-tubular capillary electrochromatographic separation.

Designing advanced stationary phases to improve separation efficiency is essential in capillary electrochromatography. Due to their outstanding performance, covalent organic frameworks have recently demonstrated considerable promise in the field of separation science. Herein, an open-tubular capillary electrochromatography method was reported using porous imine-based covalent organic framework with sufficiently available interaction sites as stationary phase. The imine-based covalent organic framework coated capillary was easily prepared via an in situ growth method at room temperature, and its separation performance was evaluated, indicating the high separation efficiency for three types of analytes, including herbicides, polybrominated dibenzofurans, and bisphenols. Moreover, the imine-based covalent organic framework coated capillary showed good reproducibility and stability, with intraday (n = 3), interday (n = 3), and column-to-column (n = 3) relative standard deviations of retention time and peak areas of less than 5%. The separation efficiency of the coated capillary remained unchanged even after 200 runs and the maximum theoretical plates reached up to 85 595 N/m for 4,4'-ethylidenebisphenol. It was predicted that the imine-based covalent organic framework stationary phase would be a strong contender for chromatographic separation with high efficiency.

Investigation on the Status Quo of Ecological Environment Construction in Northeast China from the Perspective of Dual Carbon Goals.

Since the 20th century, the resources and environment in Northeast China have changed, and it is one of the typical regions that have short-term or high-intensity environmental impacts in the world. However, due to the excessive consumption of regional resources and strong environmental pollution to the atmospheric environment, development is being greatly affected. Maintaining the natural ecological environment has become a very urgent task. This paper studies the important ecological environment problems in Northeast China from the perspective of double carbon goals. The study points out that there are ecological problems in Northeast China, such as the lack of forest resources, the aggravation of desertification, the decline of black soil quality, and the shrinkage of wetlands, which are severe urban environmental protection problems. At the same time, affected by the trend of world environmental change, policy drivers in Northeast China, and some relatively new environmental pollution problems, the natural environmental quality of Northeast China will still have a significant decline in the future. The future development of Northeast China will be based on the perspective of double carbon goals, constantly improve the ecological environment monitoring system, strengthen the research of scientific and technological system, strengthen innovation, and vigorously develop circular economy and further improve the construction of basic systems. Through a series of ecological environment governance and the coordinated development of economy and ecological environment, the dual growth of economy and ecological environment in Northeast China will be realized, and the overall revitalization of the old industrial zone in Northeast China will be realized.

Dithizone-functionalized C18 online solid-phase extraction-HPLC-ICP-MS for speciation of ultra-trace organic and inorganic mercury in cereals and environmental samples.

A simple and efficient dithizone-functionalized solid-phase extraction (SPE) procedure, online coupled with high-performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry, was developed for the first time for enrichment and determination of ultra-trace mercury (Hg) species (inorganic divalent Hg (Hg(II)), methylmercury (CH3Hg(II)) and ethylmercury (C2H5Hg(II)) in cereals and environmental samples. In the proposed method, functionalization of the commercial C18 column with dithizone, enrichment, and elution of the above Hg species can be completed online with the developed SPE device. A simple solution of 2-mercaptoethanol (1% (V/V)) could be used as an eluent for both the SPE and HPLC separation of Hg species, significantly simplifying the method and instrumentation. The online SPE method was optimized by varying dithizone dose, 2-mercaptoethanol concentration, and sample volume. In addition, the effect of pH, coexisting interfering ions, and salt effect on the enrichment was also discussed. Under the optimized conditions, the detection limits of Hg species for 5 mL water sample were 0.15 ng/L for Hg(II), 0.07 ng/L for CH3Hg(II), and 0.04 ng/L for C2H5Hg(II) with recoveries in the range of 85%-100%. The developed dithizone-functionalized C18 SPE column can be reused after a single functionalization, which significantly simplifies the enrichment step. Moreover, the stability of Hg species enriched on the SPE column demonstrated its suitability for field sampling of Hg species for later laboratory analysis. This environment-friendly method offers a robust tool to detect ultra-trace Hg species in cereals and environmental samples.

Decreased bioavailability of both inorganic mercury and methylmercury in anaerobic sediments by sorption on iron sulfide nanoparticles.

Methylmercury (MeHg), derived via inorganic mercury (Hg(II)) methylation by anaerobic microorganisms, is a neurotoxic contaminant causing concern worldwide. Establishing how to reduce Hg(II) methylation and MeHg bioavailability is essential for effective control of Hg pollution. Iron sulfide nanoparticles (FeSNP) is a promising passivator for Hg(II) methylation. However, its effect on the fate of MeHg in aquatic systems remains poorly understood. This study investigated the effect of FeSNP on Hg(II) bioavailability, MeHg production and bioavailability in aquatic environments. Results demonstrated that FeSNP rapidly sorbed Hg(II) and MeHg, with sorption affected by pH, chloride ion and dissolved organic matter. Hg-specific biosensor analysis showed that Hg(II) sorbed onto FeSNP significantly reduced its bioavailability to microorganisms. Double stable isotope (199Hg(II) and Me201Hg) addition revealed that FeSNP significantly inhibited MeHg production in anaerobic sediments. Furthermore, synthetic gut juice extraction suggested that FeSNP decrease concentrations of bioavailable MeHg and Hg(II), reducing their integration into food webs. However, the sorbed MeHg and Hg(II) in sediments can be released after FeSNP oxidation, potentially enhancing the risk of exposure to aquatic organisms. Overall, these findings increase our understanding of Hg transformation and exposure risks in aquatic systems, providing valuable information for the development of in situ Hg remediation systems.

[Effect of Sulfate on the Migration and Transformation of Methylmercury in Advanced Anaerobic Digestion of Sludge].

To study the migration and transformation of methylmercury during advanced anaerobic digestion of sludge and the role of sulfate, this study investigated the migration and transformation of methylmercury during different stages of sludge anaerobic digestion (AD) with thermal hydrolysis pretreatment and under different dosages of sulfate addition. The results showed that mercury methylation occurred in the initial stage of AD (Day 1-3), the ratio of methylmercury to total mercury increased from 0.024% (range of 0.019%-0.033%) to 0.038% (range of 0.030%-0.048%), and the net increment of methylmercury increased by 3.97, 6.09, 0.17, 3.71, and 1.66 times, respectively. In the following Day 3-5, the demethylation process occurred with the net yield of methylmercury decreased by 71.25% (ranging from 67.42% to 75.10%). Sulfate inhibited the methylation of mercury in the initial stage of AD, but had little effect on it in the late stage. This was related to the reduction of the bioavailability of neutral mercury complexes by charged groups of HgHS22- and HgS22-, as well as the immobilization of iron sulfide and mercury sulfide on S2- and bioavailable mercury. Redundancy analysis (RDA) showed that mercury methylation was affected by several factors:organic substances such as propionic acid, isobutyric acid, isovaleric acid, and Fe may promote mercury methylation, whereas protein and higher pH may be inhibitors of mercury methylation in AD of sludge.

Role of metformin in treatment of patients with chronic obstructive pulmonary disease: a systematic review.

Chronic obstructive pulmonary disease (COPD) is commonly associated with type 2 diabetes mellitus (T2DM). Metformin is a first-line treatment for most patients with T2DM, and may have antiaging, antioxidant, and anti-tumour effects. A few published studies report the use of metformin for the treatment of COPD in patients with or without T2DM, but the results are inconsistent. This study aimed to confirm the effectiveness and safety of metformin as a treatment option in patients with COPD. We performed a systematic search of PubMed, EMBASE, and the Cochrane database from their starting date to December 2017. Randomised controlled trials (RCTs), controlled clinical trials, and retrospective researches reporting the use of metformin for treating patients with COPD were identified. We included a total of six articles (involving 3,467 participants) and found that metformin may benefit patients with COPD and T2DM by improving health status and symptoms, hospitalisations, and mortality. There was no effect on patients with COPD without T2DM. Metformin causes minimal increases in plasma lactate concentrations without lactic acidosis and has little impact on blood glucose and minor adverse events. Metformin is safe and effective for treating COPD in patients with concomitant T2DM.

Multi-residue analysis of veterinary drugs, pesticides and mycotoxins in dairy products by liquid chromatography-tandem mass spectrometry using low-temperature cleanup and solid phase extraction.

A multi-class multi-residue analysis method for determination of veterinary drugs, pesticides and mycotoxins in dairy products by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been established. These 17 classes, a total of 40 kinds of target compounds were chosen because their administration to food-producing animals is banned or regulated in China and may be potentially abused or misused. Samples were extracted with acetonitrile-ethyl acetate-acetic acid (49.5+49.5+1, v/v/v). Most of lipids in the extract were removed by low-temperature cleanup, prior to solid phase extraction on HLB cartridges. The quantification and confirmation of the 40 analytes were performed by LC-MS/MS with electro-spray ionization (ESI) interface in multiple reaction monitoring (MRM) mode. The limits of detection (LODs) and limits of quantification (LOQs) were 0.006-0.3µg/kg and 0.02-1.0µg/kg, respectively. The spiked recoveries in milk, yogurt, milk powder and cheese samples were from 67.3% to 106.9%. The repeatability and the within-laboratory reproducibility were less than 12.7% and 13.9%. Applying this method, our results revealed the presences of chloramphenicol, cimeterol, and flunixin at the concentration of 0.027-0.452µg/kg in some samples.

Discontinuous mixed covolume methods for parabolic problems.

We present the semidiscrete and the backward Euler fully discrete discontinuous mixed covolume schemes for parabolic problems on triangular meshes. We give the error analysis of the discontinuous mixed covolume schemes and obtain optimal order error estimates in discontinuous H(div) and first-order error estimate in L(2).

Determination of L-hydroxyproline using hydrophilic interaction chromatography coupled to tandem mass spectrometry with lyophilized concentrated extraction in milk and dairy products.

In this study, a screening and confirmation method for the determination of l-hydroxyproline (Hyp) as a target compound in milk and dairy products using high-performance liquid chromatography with tandem mass spectrometry was developed. The samples were lyophilized after acidic hydrolysis, followed by cleanup with graphitized carbon black to remove pigments. Hyp was separated by a hydrophilic interaction chromatographic column and analyzed by high-performance liquid chromatography with tandem mass spectrometry working with multiple reaction monitoring mode using an electrospray ionization interface in a positive-ion mode. Average recoveries in spiked milk and dairy products ranged from 68.0 to 101.1% with relative standard deviations between 2.0 and 11.7% (n = 7). A reagent-matched standard calibration curve was used for quantification of Hyp, with linear correlation coefficient (R(2)) > 0.99 in the concentration range of 0.1-100 µg/mL. The LOQs were from 0.25 to 5 mg/kg, which were usually sufficient to verify the Hyp in samples. The confirmation concentration of Hyp ranged from 10 to 50 mg/kg.

Ultra-performance liquid chromatography-tandem mass spectrometry determination and depletion profile of flunixin residues in tissues after single oral administration in rabbits.

An ultra-performance liquid chromatography with tandem mass spectrometric detection (UPLC-MS/MS) method was developed for the detection of flunixin residues in rabbit tissues. The samples were extracted with acidic acetonitrile, defatted with n-hexane, and then purified by HLB solid-phase extraction cartridge. Analysis was carried out on UPLC-ESI-MS/MS working with multiple reaction monitoring (MRM) mode. The limits of detection (LODs) of the method were 0.3-0.8µgkg(-1) and limits of quantification (LOQs) were 1.0-3.0µgkg(-1) in rabbit tissues, respectively. In all fortified samples at a concentration range of 1.0-300.0µgkg(-1), mean recoveries were 61.7-115.7% with relative standard deviations (RSDs) below 16%. Residue depletion of flunixin in rabbit was conducted after oral administration at a dose of 5mgkg(-1) of body weight. The average concentrations for flunixin measured 2h post-administration in kidney and intestine were significantly higher than in liver, heart and muscle. The concentrations for flunixin in all rabbit tissues were below the LOD or not detected in all tissues after 96h administration of drug. A minimum withdrawal time of 21h was indicated for residue levels in heart, liver, kidney, intestine and muscle below the maximum residue limits (MRLs).

Development of a simple method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs in milk and dairy products by ultra-performance liquid chromatography with tandem mass spectrometry.

A multi-residue analysis method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs (NSAIDs) in milk and dairy products by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been established. The sample was initially extracted and deproteinized with ascorbic acid buffer (0.01M, pH 3) and acetonitrile-ethyl acetate mixture, followed by centrifugation and evaporation, then reconstituted with acetonitrile-0.1% formic acid (1+1, v/v). After removal of lipid material by n-hexane, the sample was analyzed by UPLC-MS/MS with electro-spray ionization (ESI) interface in Multiple Reaction Monitoring (MRM) mode. The range of limits of detection (LODs) and limits of quantification (LOQs) were 0.03-0.30µg/kg and 0.10-1.00µg/kg, respectively. The recoveries in milk, milk powder, yogurt, processed cheese and milk beverage ranged from 61.7% to 117%, and the relative standard deviations (RSDs) were less than 17.9% at three spiked levels (1, 10 and 100 times of the LOQ). Matrix effects were also investigated and it was determined the signals of the analytes were suppressed from 9.4% to 76.6% in processed cheese. The proposed method was also applied to incurred sample analysis. The results proved that this method was suitable for the simultaneous determination of nine subclasses of NSAIDs residues in milk and dairy products.

Simultaneous determination of thirty non-steroidal anti-inflammatory drug residues in swine muscle by ultra-high-performance liquid chromatography with tandem mass spectrometry.

An ultra-high-performance liquid chromatography with tandem mass spectrometric detection (UHPLC-MS/MS) method was established for the simultaneous determination of residues of thirty non-steroidal anti-inflammatory drugs (NSAIDs) in swine muscle. The samples were extracted with acetonitrile and phosphoric acid. The extracts were defatted with n-hexane, and then purified by HLB solid-phase extraction cartridge. Analysis was carried out on UHPLC-ESI-MS/MS working with multiple reaction monitoring mode with polarity switching. Limits of detection were between 0.4 µg/kg and 2.0 µg/kg, and limits of quantification were between 1.0 µg/kg and 5.0 µg/kg. The recoveries of NSAIDs were between 61.7% and 125.7% at spiked levels of 1.0-500 µg/kg. The repeatability was less than 8% and the within-laboratory reproducibility was not more than 12.3%. The method was reliable, convenient and sensitive.

Polymorphisms of the insertion / deletion ACE and M235T AGT genes and hypertension: surprising new findings and meta-analysis of data.

BACKGROUND: Essential hypertension is a common, polygenic, complex disorder resulting from interaction of several genes with each other and with environmental factors such as obesity, dietary salt intake, and alcohol consumption. Since the underlying genetic pathways remain elusive, currently most studies focus on the genes coding for proteins that regulate blood pressure as their physiological role makes them prime suspects. The present study examines how polymorphisms of the insertion/deletion (I/D) ACE and M235T AGT genes account for presence and severity of hypertension, and embeds the data in a meta-analysis of relevant studies. METHODS: The I/D polymorphisms of the ACE and M235T polymorphisms of the AGT genes were determined by RFLP (restriction fragment length polymorphism) and restriction analysis in 638 hypertensive patients and 720 normotensive local blood donors in Weisswasser, Germany. Severity of hypertension was estimated by the number of antihypertensive drugs used. RESULTS: No difference was observed in the allele frequencies and genotype distributions of ACE gene polymorphisms between the two groups, whereas AGT TT homozygotes were more frequent in controls (4.6% vs. 2.7%, P = .08). This became significant (p = 0.035) in women only. AGT TT genotype was associated with a 48% decrease in the risk of having hypertension (odds ratio: 0.52; 95% CI, 0.28 to 0.96), and this risk decreased more significantly in women (odds ratio: 0.28; 95% CI, 0.1 to 0.78). The meta-analysis showed a pooled odds ratio for hypertension of 1.21 (TT vs. MM, 95% CI: 1.11 to 1.32) in Caucasians. No correlation was found between severity of hypertension and a specific genotype. CONCLUSION: The ACE I/D polymorphism does not contribute to the presence and severity of essential hypertension, while the AGT M235T TT genotype confers a significantly decreased risk for the development of hypertension in the population studied here. This contrasts to the findings of meta-analyses, whereby the T allele is associated with increased risk for hypertension.

Active collaboration with primary care providers increases specialist referral in chronic renal disease.

BACKGROUND: Late referral to specialist nephrological care is associated with increased morbidity, mortality, and cost. Consequently, nephrologists' associations recommend early referral. The recommendations' effectiveness remains questionable: 22-51% of referrals need renal replacement therapy (RRT) within 3-4 months. This may be due to these recommendations addressing the specialist, rather than the primary care providers (PCP). The potential of specialist intervention aiming at slowing progression of chronic renal failure was introduced individually to some 250 local PCPs, and referral strategies were discussed. To overcome the PCPs' most often expressed fears, every referred patient was asked to report back to his PCP immediately after the initial specialist examination, and new medications were prescribed directly, and thus allotted to the nephrologist's budget. METHODS: In retrospective analysis, the stage of renal disease in patients referred within three months before the introductory round (group A, n = 18), was compared to referrals two years later (group B, n = 50). RESULTS: Relative number of patients remained stable (28%) for mild/ moderate chronic kidney disease (MMCKD), while there was a noticeable shift from patients referred severe chronic kidney disease (SCKD) (group A: 44%, group B: 20%) to patients referred in moderate chronic kidney disease (MCKD) (group A: 28%, group B: 52%). CONCLUSION: Individually addressing PCPs' ignorance and concerns noticeably decreased late referral. This stresses the importance of enhancing the PCPs' problem awareness and knowledge of available resources in order to ensure timely specialist referral.