ABSTRACT
Nitrate is one of the most common contaminants in food and the environment and mainly arises from intense human activities. Electrochemical sensors have been considered as one of the most promising analytical tools for the rapid detection of nitrate in food and environmental matrices due to their quick response, high sensitivity, ease of operation and miniaturisation, and low sample and power consumption. In this review, we summarise advances in sensors for electrochemical analysis of nitrate over the past decade. We also discuss the application of electrochemical sensing systems for the determination of nitrate in the matrices of fresh water, seawater, food, soil and particulate matter.
ABSTRACT
Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, laboratory-on-chip devices, and near-field imaging techniques. Oil nanodroplets can be produced on a solid-liquid interface in a simple step of solvent exchange in which a good solvent of oil is displaced by a poor solvent. In this work, we experimentally and theoretically investigate the formation of nanodroplets by the solvent exchange process under well-controlled flow conditions. We find significant effects from the flow rate and the flow geometry on the droplet size. We develop a theoretical framework to account for these effects. The main idea is that the droplet nuclei are exposed to an oil oversaturation pulse during the exchange process. The analysis shows that the volume of the nanodroplets increases with the Peclet number Pe of the flow as â Pe(3/4), which is in good agreement with our experimental results. In addition, at fixed flow rate and thus fixed Peclet number, larger and less homogeneously distributed droplets formed at less-narrow channels, due to convection effects originating from the density difference between the two solutions of the solvent exchange. The understanding from this work provides valuable guidelines for producing surface nanodroplets with desired sizes by controlling the flow conditions.
ABSTRACT
OBJECTIVE: To explore the clinical significance of G6PD gene mutation detection in female heterozygote with G6PD deficiency. METHODS: G6PD activity and fourteen common G6PD gene mutations in female blood samples were detected by biochemical phenotype detection and PCR-reverse dot blotting, respectively. Unidentified genotype of G6PD positive samples was further ascertained by direct DNA sequencing. The results from two methods were compared and analyzed. RESULTS: A total of 493 unrelated females were enrolled, and the G6PD activity and G6PD mutations was detected. Among them, 473 females were found to be normal in G6PD activity and 20 females with G6PD deficiency, and the detection rate by G6PD activity method was 4.06%. In all enrolled females, G6PD gene mutations, including the mutation of c.1311 Cï¼T, were identified in 130 females, and the detection rate was 26.3%. Detection rate of the mutations that can lead to G6PD deficiency was 8.11%. The detection rates between the two methods were significantly different (Pï¼0.01). The misdiagnosis rate of the G6PD activity detection reached 49. 94% for the female heterozygotes. Eight G6PD mutations and 13 mutation patterns were identified in the research, and most of mutation patterns were single nucleotide missense mutation. In addition to c.1311Cï¼T mutation, the most common mutations were c.1376Gï¼T, c.1388Gï¼A and c.95 Aï¼G. G6PD mutations were identified in 19 of 20 females with G6PD deficiency, and were also detected in 21 of 473 females with normal G6PD activity, of which the rate of heterozygous mutation was 90.88%. CONCLUSION: The phenotype detection based on G6PD enzyme activity alone is not sufficient for the diagnosis of female heterozygotes. The detection of G6PD mutations that covers the common mutations in specified region can effectively identify the female heterozygotes with normal G6PD activity.
Subject(s)
Glucosephosphate Dehydrogenase Deficiency , Female , Genotype , Glucosephosphate Dehydrogenase/genetics , Glucosephosphate Dehydrogenase Deficiency/genetics , Heterozygote , Humans , MutationABSTRACT
Recent developments in rechargeable battery technology have seen a shift from the well-established Li-ion technology to new chemistries to achieve the high energy density required for extended range electric vehicles and other portable applications, as well as low-cost alternatives for stationary storage. These chemistries include Li-air, Li-S, and multivalent ion technologies including Mg2+ , Zn2+ , Ca2+ , and Al3+ . While Mg2+ battery systems have been increasingly investigated in the last few years, Ca2+ technology has only recently been recognized as a viable option. In this first comprehensive review of Ca2+ ion technology, the use of Ca metal anodes, alternative alloy anodes, electrolytes suitable for this system, and cathode material development are discussed. The advantages and disadvantages of Ca2+ ion batteries including prospective achievable energy density, cost reduction due to high natural abundance, low ion mobility, the effect of ion size, and the need for elevated temperature operation are reviewed. The use of density functional theory modeling to predict the properties of Ca-ion battery materials is discussed and the extent to which this approach is successful in directing research into areas of promise is evaluated. To conclude, a summary of recent achievements is presented and areas for future research efforts evaluated.
ABSTRACT
A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li2CO3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H2SO4, and the cathode material LiNi1/3Co1/3Mn1/3O2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi1/3Co1/3Mn1/3O2 is miro spherical morphology without any impurities, which can meet with LiNi1/3Co1/3Mn1/3O2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling.
Subject(s)
Electric Power Supplies , Lithium , China , Electrodes , Recycling , RegenerationABSTRACT
Magnesium and its alloys have shown a great potential in effective hydrogen storage due to their advantages of high volumetric/gravimetric hydrogen storage capacity and low cost. However, the use of these materials in fuel cells for automotive applications at the present time is limited by high hydrogenation temperature and sluggish sorption kinetics. This paper presents the recent results of design and development of magnesium-based nanocomposites demonstrating the catalytic effects of carbon nanotubes and transition metals on hydrogen adsorption in these materials. The results are promising for the application of magnesium materials for hydrogen storage, with significantly reduced absorption temperatures and enhanced ab/desorption kinetics. High level Density Functional Theory calculations support the analysis of the hydrogenation mechanisms by revealing the detailed atomic and molecular interactions that underpin the catalytic roles of incorporated carbon and titanium, providing clear guidance for further design and development of such materials with better hydrogen storage properties.
ABSTRACT
A simple method for the preparation of monodisperse protein-loaded polymer microspheres is presented in this paper. The method is based on the co-extrusion of an internal phase of an aqueous protein solution and an external phase of an organic polymer solution through a 200-micron-sized hole. Controlled in the correct flow region, this process produces a core-shell-structured laminar liquid jet, which breaks to form monodisperse compound liquid droplets. Stabilized in a dilute aqueous polyvinyl alcohol (PVA) solution, the droplets are converted into solid protein-loaded polymer microspheres through evaporation of the organic solvent. Results show that preparation parameters such as polymer concentration, total flow rate, flow rate ratio of the aqueous to organic phase have significant effects on the mean particle size, particle morphology and protein encapsulation efficiency (EE). The results of biodegradation and the protein release characteristics of the polymer microspheres are also presented.
Subject(s)
Drug Compounding , Microspheres , Polymers/chemistry , Proteins/chemistry , Drug Carriers , Particle Size , Polyesters/chemistry , Polymers/analysis , Proteins/metabolismABSTRACT
Self-assembled porous silica materials with adjustable structures and tunable pore sizes have important applications in catalysis, separation, and nanoscience. Organic cosolvents such as 1,3,5-trimethylbenzene (TMB) can be used to synthesize large pore mesoporous materials. In this study, we systematically studied the influence of the time of TMB addition on the self-assembled organic/inorganic composite structures in a nonionic block copolymer templating system. By controlling the time at which TMB is added to the system, an evolution from multilamellar vesicle to ordered hexagonal mesostructure has been observed. TMB is a swell agent in our synthesis, an increase in the delay of TMB addition can kinetically reduce the amount of TMB penetrating into the hydrophobic core of embryonic mesostructure, leading to cooperatively self-assembled vesicular and mesostructured materials with decreased packing parameters. Our results have shown that, in the simple synthesis system of traditional SBA-15 material, siliceous materials with a range of structures can be rationally designed and synthesized through the addition of TMB at different times. Such materials with tunable pore structures have potential applications as microcapsules and controlled release/delivery carriers.