Synthesis of Pyridylazo-substituted Chromogenic Calix[4]arenes

This letter reports a novel method for preparing chromogenic calix[4]arenes, in which the 4-aminopyridine was diazotized with isoamyl nitrite in EtONa/EtOH, and mono(azo)-, bis(azo)- and tetra(azo)-substituted calix[4]arenes were obtained as main product respectively by diazo-coupling in different molar ratio to calix[4]arene in non-aqueous solution at 0-5℃.

STUDIES ON THE DISSOCIATION OF THE RARE-EARTH CHROMOGENIC REAGENT CHLOROPHOSPHONAZO-mA

Chlorophosphonazo-mA [2-(4-Chloro-2-phosphonobenzenenazo)-7-(3-ac-etylbenzenenazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid] is a derivative of unsyr.metrical bisazo chromotropic acid,with the following structureIn 1979,it was first reported that the title compound could be used in the spectro determination of the total amount of micro rare-earths existing in spherical graphite cast iron and weak alloy steel and direct spectro determination of the total amount of the rare-earths and the fractional amount of the light and heavy rare-earths when used together with chlophosphonazo-mN It is a rather ideal chromogenic reagent to determine the total amount of the rare-earths.It was also discovered in later work to be usefulin the spectro determination of the elements uranium(VI)and calciumetc[3,4]In order to make a further study for the thermodynamic properties and kinetic characteristics of the reagent when complexing with the rare-earths we have first investigated the ionization of the

A New Chromogenic Diester-calix[4]crown Receptor for Ca^(2+)

A diester-calix[4]crown-4-ether bearing mono (azophenol) moiety shows a larger spectral change toward Ca2+ than other alkali and alkaline eafth cations.

Exploration on Research Methods for Exploring Human Response to Luminous Environment with Chromogenic Windows Applied

Chromogenic windows enable both energy-saving and daylighting regulation.However,the human response to the luminous environment affected by them is difficult to test,since their features of dynamic change and tinting automatically.This study explores the research methods,including experimental design and statistical analysis,by literature review and an experiment demonstration.The results show that a proper size of the test room is significant to obtain desired data,and the advanced VR technologies have the potential to be applied for testing these dynamic variables.Bayesian approaches are recommended to be tried and get more accurate interference about the experimental results.

Single-Crystalline Organoiridium Complex for Gas-Triggered Chromogenic Switches and Its Applications on CO Detection and Reversible Scavenging

Summary of main observation and conclusion Nonporous molecular single crystals of coordinatively unsaturated 16-electron metallacycle are found to undergo highly selective-yet reversible-binding of CO over CH4,H2,N2,CO2,various volatile organic compounds and water,through binding of the molecule to its metal centers.Carbon monoxide is taken up by black crystals and subsequently liberated from the corresponding orange CO adduct by reversible metal coordination,the structural evidence obtained from in situ X-ray diffraction.The single-crystallinity of the metallacycle is retained even after several cycles.The material,when adsorbed on silica,shows remarkable sensitivity and selectivity for CO,allowing visual CO sensing in the solid state.The metallacycle offer the possibility of serving as readily regenerable scavenger for removing trace CO from gas mixtures with N2.

Screening agars for MRSA:evaluation of a stepwise diagnostic approach with two different selective agars for the screening for methicillin-resistant Staphylococcus aureus(MRSA)

Background: Colonization with methicillin-resistant Staphylococcus aureus(MRSA) poses a hygiene risk that does not spare field hospitals or military medical field camps during military deployments. Diagnostic options for unambiguously identifying MRSA isolates are usually scarce in military environments. In this study, we assessed the stepwise application of two different selective agars for the specific identification of MRSA in screening analyses.Methods: Nasal swabs from 1,541 volunteers were subjected to thioglycollate broth enrichment and subsequently screened on CHROMagar MRSA selective agar for the identification of MRSA. The MRSA identity of suspiciouslooking colonies was confirmed afterwards or excluded by another selective agar, chrom ID MRSA. All isolates from the selective agars with MRSA-specific colony morphology were identified by biochemical methods and mass spectrometry.Results: The initial CHROMagar MRSA screening identified suspicious colonies in 36 out of 1541 samples. A total of 25 of these 36 isolates showed MRSA-like growth on chrom ID agar. Out of these 25 isolates, 24 were confirmed as MRSA, while one isolate was identified as Staphylococcus kloosii. From the 11 strains that did not show suspicious growth on chrom ID agar, 3 were methicillin-sensitive Staphylococcus aureus(MSSA, with one instance of cocolonization with Corynebacterium spp.), 2 were confirmed as MRSA(with 1 instance of co-colonization with MSSA), 2 were lost during passaging and could not be re-cultured, one could not be identified by the applied approaches, and the remaining 3 strains were identified as Staphylococcus saprophyticus, Staphylococcus hominis(co-colonized with Macrococcus caseolyticus) and Staphylococcus cohnii, respectively.Conclusion: The application of the selective agar CHROMagar MRSA alone proved to be too non-specific to allow for a reliable diagnosis of the presence of MRSA. The combined use of two selective agars in a stepwise approach reduced this non-specificity with an acceptably low loss of sensitivity. Accordingly, such a stepwise screening approach might be an option for resource-restricted military medical field camps.

Determination of Manganese in Tap Water by a New Extraction-Photometric Method

The heteroligand complex of manganese with 1,10-phenantroline and o-nitrobenzolazosalicylic acid has been investigated by spectrophotometric method. The condition of complexing and extraction, physical-chemical and analytical characteristics of this complex have been found. Complex formation is observed in the pH range 5 - 11. Extraction constant was found as 5.3 × 1012, stability constant was found as lgβK = 9.03?± 0.03. Molar absorptivity is ε = (1.36 ± 0.08) × 104 l·g﹣1·cm﹣1. Beer's law is obeyed in the range of 1.0 - 22.5 μkg manganese (II). The extraction-photometric methods of manganese determination have been worked out. The influence of diverse ions on determination of manganese (II) has been studied. The proposed method was applied successfully to determine amount of manganese in tap water.

Research progress of CRISPR/Cas systems in nucleic acid detection of infectious diseases

Infectious diseases are a serious threat to human health,and accurate,rapid and convenient early detection of pathogens is the first step of active treatment.Technologies that detect pathogens have advanced significantly because of the development of fundamental disciplines and the integration of multidisciplinary fields.Among these technologies,nucleic acid detection technology is preferred because of its rapid measurement,accuracy and high sensitivity.The CRISPR/Cas system,consisting of Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)and CRISPR‐associated(Cas),is an adaptive immune system that specifically recognizes,binds and cleaves exogenous invasive nucleic acids.The CRISPR/Cas system is widely found in bacteria and archaea.Researchers have developed nucleic acid detection technologies with single‐molecule sensitivity,single‐base precision specificity,portability and low cost based on the specific cleavage and trans‐cleavage activities of the CRISPR/Cas system.The next generation of in‐vitro diagnostics is shifting to nucleic acid technology because this technology shows promise in a wide range of applications in resource‐constrained environments.In this review,the development and mechanism of the CRISPR/Cas system are presented together with representative CRISPR/Cas applications in nucleic acid detection.Additionally,the review summarizes future perspectives and trends of the CRISPR/Cas system in nucleic acid detection.

Kinetic analysis of γ-glutamyltransferase reaction process for measuring activity via an integration strategy at low concentrations of γ-glutamyl p-nitroaniline

At 0.12 mmol/L γ-glutamyl p-nitroaniline(GGPNA),an improved integrated method was developed for kinetic analysis of γ-glutamyltransferase(GGT) reaction process and the integration with the classical initial rate method to measure serum GGT.For the improved integrated method,an integrated rate equation,which used the predictor variable of reaction time and considered inhibitions by both GGPNA and products,was nonlinearly fit to GGT reaction processes.For the integration strategy,classical initial rates were estimated when GGPNA consumption percentages were below 50%;otherwise,maximal reaction rates of GGT were estimated by the improved integrated method and converted into initial rates according to the differential rate equation at 0.11 mmol/L GGPNA.The inte-gration strategy was validated using optimized GGT kinetic parameters and 10-s intervals to record reaction curves within 8.0 min.By the integration strategy,there was a linear response from 0.9 to 32.0 U/L GGT,coefficients of variation were below 3.5%for GGT from 8.0 to 32.0 U/L(n=5) ,and GGT activities in clinical sera responded linearly to their classical initial rates at 2.00 mmol/L GGPNA with an expected slope.Therefore,the integration strategy was successful in measuring GGT at 0.12 mmol/L GGPNA.

Self-assembled all-inclusive organic-inorganic nanoparticles enable cascade reaction for the detection of glucose

Traditional colorimetric glucose biosensor generally involves complex assay procedures.Free labile enzymes and peroxidase substrates are used separately for triggering a chromogenic reaction.These limits result in inferior enzyme stability and defective enzymatic catalytic efficiency,making it hard to routinely utilize them for the direct and fast test of glucose.In this work,we provide an all-inclusive substrates/enzymes nanoparticle employed 3,3’5,5’-tetramethylbenzidine(TMB) as chromogenic substrates and glucose oxidase(GOx)/horseradish peroxidase(HRP) as signal amplifier enzymes(TMB-GH NPs) by the molecule self-assembly technique.The "all-inclusive" nanoparticles can realize the tandem colorimetric reactions,and the oxidation product of TMB(ox-TMB) exhibits a strong NIR laserdrive n photothermal effect,thus allowing qua ntitative photothermal detection of glucose.Owing to the restriction of the molecular motion of GOx,HRP,and TMB,the distance of mass transfer between substrates was s hortened largely,leading to improved catalytic activity for glucose.Overall,our strategy will simplify the analysis procedure,furthermore,these integrated nanoparticles not only display higher stability and activity than that of the free GOx/HRP system and possesses an excellent performance for colorimetric and photothermal bioassay of glucose simultaneously.We believe that this unique technique will give good inspirations to develop simple and precise methods for bioassay.

Naked Eye and Selective Detection of Copper(II) in Mixed Aqueous Media Using a Cellulose-based Support

A new colorimetric sensor based-azo dye for Cu^2+ detection was synthesized and characterized by FTIR and NMR spectroscopies. The results showed that the azo dye had a high selective and sensitive recognition toward Cu^2+. The solution containing the sensor changed color from pink to pale yellow with a hypsochromic shift in the presence of Cu^2+. The sensor selectivity and sensitivity toward Cu^2+ ions were investigated by colorimetry and UV-Vis spectroscopy. For practical applications, a cellulosic textile test strip for high-selectivity detection of Cu^2+ ions in aqueous solution was developed using the synthesized azo dye as chromogenic chemosensor molecule, while using a solid cellulose textile as a substrate. As a result, a spectacular color change of the test strip was observed do pending on the amount of copper ions in contact with the strip, which allows an estimation of Cu^2+ concentration by naked eye.