High-performance composite cathodes for Alkaline electrolysis of water

A procedure for preparing and modifying composite electrode materials, allowing preparation of high-performance Ni-based catalysts for water electrolyzers with alkaline electrolyte, is reported. Electrodes for cathodic process, fabricated using this procedure, allow the power consumption for hydrogen production in alkaline water electrolyzers to be considerably reduced relative to known analogs used in Russia and other countries.     

High-performance bulk heterojunction-based photocathode with facile architecture for photoelectrochemical water splitting

Organic semiconductors are promising candidates as photoactive layers for photoelectrodes used in photoelectrochemical (PEC) cells due to their excellent light absorption and efficient charge transport properties with the help of interfacial materials. However, the use of multilayers will make the charge transfer mechanism more complicated and decrease the PEC performance of the photoelectrode caused by the increased contact resistance. In this work, a PM6:Y6 bulk heterojunction (BHJ)-based photocathode is fabricated for efficient PEC hydrogen evolution reaction (HER) in an acidic aqueous solution. With RuO₂ as an interfacial modification layer, the photocathode with a simple structure (fluorine-doped tin oxide (FTO)/PM6:Y6/RuO₂) generates a maximum photocurrent density up to ?15 mA/cm² at 0 V vs. reference hydrogen electrode (RHE), outperforming all previously reported BHJ-based photocathodes in terms of PEC performance. The highest ratiometric power-saved efficiency of 3.7% is achieved at 0.4 V vs. RHE.     

Spectrophotometric determination of transition temperature in potassium myristate water system

A spectrophotometric method with an attachment made by ourselves was used to measure the transition temperatures (T_JL) from aqueous solution into lyotropic liquid crystalline phase of potassium myristate (KMy). The transition process was shown clearly by an absorbance, A, vs. temperature, T, curve. TIL was obtained from the intersection point of two curves on a plot of δA / δT vs.T¯ T_JL measured by our method can be compared with reported data. The solubilization of small amounts of inorganic (potassium oxidate) or organic (diphenyl ketone) additive can shift the transition temperature, and T_JL rose with increasing concentration of additive. Potassium oxidate or diphenyl ketone in KMy-H₂O system made the system form a lamellar liquid crystal instead of the original hexagonal liquid crystal, which was considered to relate to increase of the T_JL.     

High-performance potassium poly(heptazine imide) films for photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is an appealing approach by which to convert solar energy into hydrogen fuel. Polymeric semiconductors have recently attracted intense interest of many scientists for PEC water splitting. The crystallinity of polymer films is regarded as the main factor that determines the conversion efficiency. Herein, potassium poly(heptazine) imide (K-PHI) films with improved crystallinity were in situ prepared on a conductive substrate as a photoanode for solar-driven water splitting. A remarkable photocurrent density of ca. 0.80 mA cm⁻² was achieved under air mass 1.5 global illumination without the use of any sacrificial agent, a performance that is ca. 20 times higher than that of the photoanode in an amorphous state, and higher than those of other related polymeric photoanodes. The boosted performance can be attributed to improved charge transfer, which has been investigated using steady state and operando approaches. This work elucidates the pivotal importance of the crystallinity of conjugated polymer semiconductors for PEC water splitting and other advanced photocatalytic applications.

Potassium poly(heptazine imide) photoanode is synthesized, and owing to the improved crystallinity, it has presented a remarkable performance for solar-driven water splitting.     

Effect of temperature fluctuation on hydrate-based CO_2 separation from fuel gas

A new method of temperature fluctuation is proposed to promote the process of hydrate-based CO2 separation from fuel gas in this work according to the dual nature of CO2 solubility in hydrate forming and non-hydrate forming regions [1].The temperature fluctuation operated in the process of hydrate formation improves the formation of gas hydrate observably.The amount of the gas consumed with temperature fluctuation is approximately 35% more than that without temperature fluctuation.It is found that only the temperature fluctuation operated in the period of forming hydrate leads to a good effect on CO2 separation.Meanwhile,with the proceeding of hydrate formation,the effect of temperature fluctuation on the gas hydrate gradually reduces,and little effect is left in the completion term.The CO2 separation efficiencies in the separation processes with the effective temperature fluctuations are improved remarkably.     

High-performance electrocatalyst of vanadium-iron bimetal organic framework arrays on nickel foam for overall water splitting

The development of active,low-cost and durable bifunctional electrocatalysts toward both oxygen evolution reaction(OER) and hydro gen evolution react ion(HER) a re important for overall water splitting.Here,well-defined arrays of vanadium-iron bimetal organic frameworks(VFe-MOF) with controllable stoichiometry have been successfully prepared on nickel foam(NF).The as-fabricated VFe-MOF@NF electrode exhibits excellent electrocatalytic activity and durability for OER and HER in alkaline medium.The material's overpotentials of 10 mA/cm~2 are 246 mV for OER and 147 mV for HER,respectively.The electrolyzer made from the VFe-MOF@NF electrodes as both the cathode and anode in 1 mol/L KOH needs only a voltage of 1.61 V to reach a current density of 10 mA/cm~2.The superior performance of VFeMOF@NF can be attributed to the morphological control and electronic regulation of the bimetals,that is,1) the exposure of the active sites at electrocatalyst/electrolyte interfaces due to the array structure;2)the synergistic effect of vanadium and iron metals on electro-catalyzing the overall water splitting.     

Correlation for the variations with temperature of solute solubilities in high temperature water

Methods for estimating solute solubilities in high temperature water both below and above its boiling point (under pressure) are needed for applications of this medium in processing applications such as sub-critical water extraction, reaction chemistry in heated water, and in the material sciences. There is a paucity of data and correlative methods for estimating solute solubilities under these conditions; the limited existing methods are based on a limited solubility data base, and in some cases predicted solubility values are in quite serious disagreement with experimentally derived data. Here available solute solubility data both above and below the boiling point of water has been correlated for diverse solute types consisting of hydrocarbons, essential oil components, pesticides, polyphenolic compounds, as well as solutes exhibiting high solubility in water under the stated conditions. Utilizing solubility data from diverse sources, appropriate conversions and equations have been derived for converting all solubility data to a mole fraction basis, while the other required physicochemical parameters, such as melting point, boiling point, critical properties, have been estimated, when necessary, largely by group contribution-based methods. A solubility model based on such physicochemical parameters and critical properties of the solutes was derived. An excellent correlation is obtained for x_{c (estimated)}versus x_c using this approach and the prediction of solute solubility in water as a function of temperature was found to be excellent for 431 data points representing the solubility of 34 solutes in the temperature range between 298 and 573 K.     

High-performance affinity chromatography system for the rapid, efficient assay of glycated albumin.

A high-performance affinity chromatographic system was constructed and shown to permit highly reproducible, rapid, automatic assays of serum glycated albumin (GA) by separation of albumin (Alb) on an anion-exchange column (Asahipak ES-502N) packed with a vinyl alcohol copolymer bearing diethylamino groups and consecutive separation of GA on a column packed with a vinyl alcohol copolymer bearing boronate groups. The first column selectively retained Alb free of other serum proteins and permitted at least a 95% recovery of sample Alb. The purity of the Alb peak was confirmed by two-dimensional electrophoresis. Chromatographic analyses of human serum Alb incubated with glucose on the second column showed that the peak area for GA increased in accordance with the incubation time and suggested selective adsorption of GA on the second column. Optimization of the conditions for the two-column system reduced the analysis time to 10 min. Analyses of human sera with the present system showed GA to be 16.1 +/- 1.1% (mean +/- S.D.) of total Alb in non-diabetic children and 39.9 +/- 9.1% (mean +/- S.D.) in diabetic children (0-17 years old).     

Stable partial nitritation of mature landfill leachate in a continuous flow bioreactor: Long-term performance,microbial community evolution,and mechanisms

A continuous flow bioreactor was operated for 300 days to investigate partial nitritation (PN) of mature landfill leachate, establishing the long-term performance of the system in terms of the microbial community composition, evolution, and interactions. The stable operation phase (31–300 d) began after a 30 days of start-up period, reaching an average nitrite accumulation ratio (NAR) of 94.43% and a ratio of nitrite nitrogen to ammonia nitrogen (NO₂⁻-N/NH₄⁺-N) of 1.16. Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks, which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank, and organic matter degrading bacteria in the anoxic tank. The ammonia-oxidizing bacteria (AOB) Nitrosomonas was found to be the key functional bacteria, exhibiting an increase in abundance from 0.27% to 6.38%, due to its collaborative interactions with organic matter degrading bacteria. In-situ inhibition of nitrite-oxidizing bacteria (NOB) was achieved using a combination of free ammonia (FA) and free nitrous acid (FNA), low dissolved oxygen (DO) with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO₂⁻-N/NH₄⁺-N, without an adverse impact on AOB. The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria, were found to contribute to the enhanced PN performance and microbial community structure stability. These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.     

High-performance separation techniques hyphenated to mass spectrometry for ganglioside analysis

Gangliosides, sialic-acid-containing glycosphingolipids are involved in numerous biological processes and play essential roles in severe pathologies, with predilection in those of the central nervous system. Formerly, ganglioside composition and quantity were assessed exclusively by thin-layer chromatographic (TLC), immunochemical, and immunohistochemical methods, which have limited effectiveness being unable to detect minor components in mixtures of high heterogeneity. Increased awareness of the biological importance of gangliosides stimulated the development of analytical methods that are better amenable to complex ganglioside mixtures. More recently, MS in online conjunction with high-performance separation techniques brought a significant progress to the field. This review highlights the state-of-the-art development and application of separation methods online coupled to MS for ganglioside analysis. Most original and successful protocols based on GC-MS, LC-MS, and CE-MS are presented here together with the special instrumental and sample preparation requirements to be met for effective ganglioside separation, detection, and structural identification. Finally, the advantages and downsides of each methodology as well as the perspectives for simplification, standardization, and upgrading are assessed.     

Low temperature electrochemistry as a mechanistic probe for the partial reduction of heterocycles

The reduction of a series of electron deficient aromatic heterocycles has been examined using electrochemical techniques: the analysis was performed under anhydrous conditions at low temperature, so as to mimic typical synthetic reducing conditions.     

High-performance liquid chromatographic determination of dinitroaniline herbicides in soil and water.

A high-performance liquid chromatographic method for the simultaneous determination of the dinitroaniline herbicides dinitramine, ethalfluralin, trifluralin, pendimethalin and isopropalin in soil and surface water is reported. The soil was extracted with diethyl ether and analysed without any clean-up. The water was analysed after purification and concentration on a C18 cartridge. The average recoveries were in the range 89-104%. The detection limits for the five herbicides were 0.02 mg/kg in dry soil and 0.5 micrograms/l in surface water.     

High-performance liquid chromatography with hydride generation/atomic absorption spectrometry for the determination of arsenic species with application to some water samples

High-performance liquid chromatography (h.p.l.c.) is used for separation of arsenite, arsenate, monomethylarsinate (MMA) and dimethylarsonate (DMA) followed by continuous sodium tetrahydroborate reduction and atomic absorption spectrometric detection. Sample preconcentration, offering improved detection limits for the individual species and the removal of matrix interferences, is achieved with a pellicular anion-exchange column. The arsenic species are then separated on a strong anion-exchange column placed in series with the preconcentration column. Detection limits of 2 ng (as arsenic) for arsenite, arsenate and MMA, and 1 ng for DMA. Results for arsenic species in soil waters and commercial bottle waters are given.     

Three-point frequency fluctuation correlation functions of the OH stretch in liquid water

Characterizing the dynamics of the OH stretch in isotopically substituted liquid water (HOD in D(2)O) in terms of three-point frequency fluctuation correlation functions and joint probability densities shows that dynamics during hydrogen bond rearrangements occur primarily along a coordinate which is perpendicular to the spectroscopic coordinate. Molecular dynamics simulations show that three-point correlation functions are sensitive to this motion, unlike two-point correlation functions, and can select sets of trajectories which linger in the area of the transition state. Three-dimensional-infrared correlation spectroscopy could potentially measure these dynamics, though motional narrowing significantly changes the shape of the resulting spectra.     

Controlling water temperature for efficient coal/gangue recognition

Coal and gangue (black-gray solid wastes in coal) recognition is vital to avoid waste of resources and pollution of the environment during the coal production. Considering their color/temperature is very close to each other, the traditional visible image and infrared image analyzing method is hard to obtain satisfied recognition efficiency. Therefore, a new idea of the ‘liquid intervention + infrared monitoring’ method was proposed to improve the recognition efficiency. In this article, the coal/gangue recognition experiments with different water temperatures were conducted, and the infrared thermal imager was used to record temperature variation after water intervention. The results show that when the water temperature is lower than the ambient temperature, the temperature difference between coal and gangue reaches the maximum value within 10 s, which is five times that without water intervention. The mean value of temperature difference between coal and gangue shows an approximate linear downward trend with the increasing of water temperature. The results indicate that under the condition of water intervention, it is recommended to choose water with a temperature below the ambient air, which may be a new approach to improve the coal/gangue recognition efficiency under different complex environments in underground coal mines.     

A water purification system for microanalysis

A water purification system producing conductivity water is described. It involves first distillation, second distallation from acidified potassium permanganate, and deionation by separate bed strong cation and anion-exchange resins. The purified water proved the validity for microanalysis by conductivity and spectrophotometry. The apparatus can be assembled easily in a laboratory from all Pyrex glass Quickfit units with some glass elaboration.     

High-performance liquid chromatography column switching applied to the trace determination of herbicides in environmental and drinking water samples

A selective and sensitive coupled-column high-performance liquid chromatographic method is developed for the simultaneous determination of 5 phenylurea herbicides (monuron, linuron, isoproturon, monolinuron, and diuron) in environmental and drinking water samples. Sample clean-up is performed automatically by means of a column switching technique. Using 2 octadecyl silica columns connected via two programmable 6-port valves and ultraviolet detection at 244 nm, the aforementioned compounds can be determined at the low concentration levels required for pesticide residue analysis in water samples. A mobile phase consisting of a mixture of methanol-water (55:45, v/v) is pumped at 1 mL/min. For the 5 phenylureas, high recoveries ranging from 94.9 to 101.6%, good reproducibility with relative standard deviations lower than 5%, and wide linear ranges up to 20 micrograms/L are observed with determination limits of 0.05 microgram/L. The method is successfully applied to the screening of different environmental water samples such as surface, ground, rain, and drinking water.     

High-performance liquid chromatographic method for screening disorders of aromatic acid metabolism using a multi-detection system

This paper describes the use of a high-performance liquid chromatograph equipped with an ultraviolet multi-detection system for the analysis of aromatic acids to help establish a high-risk screening system for disorders of organic acid metabolism. The peak height ratios of about seventy metabolically important aromatic acids have been compiled using the multi-detection system. It may be possible to identify aromatic acids by comparing retention time and peak height ratios. The method was very effective for the diagnosis of disorders of aromatic acid metabolism.