Solubility of Potassium Acetate in Water, 2,2,2-Trifluoroethanol,Ethanol and Their Binary Mixtures at 288.15—333.15 K

The potassium acetate solutions are new potential working fluids for the closed-type reverse electrodialysis(RED) power generation system driven by thermal energy. In this paper, the solubilities of potassium acetate in water, 2,2,2-trifluoroethanol, ethanol and their binary mixtures were measured by using the laser dynamic method over the temperature range of 288.15 to 333.15 K under atmospheric pressure. The results indicate that the solubility of potassium acetate solution is influenced by both the solvent components and solution temperature evidently. Besides, it is found that the measured solubility data of the potassium acetate-water-2,2,2-trifluoroethanol solutions as per the laser dynamic method are slightly larger than that of the data obtained as per the static method. Finally, five correlation models, including the Van't Hoff model, Modified Apelblat model, Yaws model, λh model and Modified Apelblat-Jouyban-Acree model, were used to correlate the measured solubility data of those potassium acetate solutions, with the relative standard deviations within 0.23% to 1.58%.     

Study of the structure and thermal behaviour of intercalated kaolinites

Intercalation complexes of three different Hungarian kaolinites with hydrazine and potassium acetate were investigated by FT-IR (DRIFT) spectrometry, X-ray diffraction, and thermogravimetry combined with mass spectrometry. Differences were found in the thermal behaviour of the complexes as well as in the rehydration — reexpansion patterns of the heated intercalates. An XRD method is proposed for the distinction of kaolinite and 7.2 Å halloysite present in the same mineral.The authors wish to thank Dr. E. Máttyás for providing the kaolinite samples and for carrying out their chemical analysis. Financial support from the Hungarian Scientific Research Fund under grant No. OTKA-014179 is gratefully acknowledged.     

乙烯/乙酸乙烯酯共聚物中乙酸乙烯酯含量测定方法探讨

采用SH／T1591－94检测乙酸乙烯酯（VA）含量时,氢氧化钾－乙醇标准溶液的含水量是影响测定结果的主要因素。对影响因素进行了定量研究,结果表明,配制氢氧化钾－乙醇标准溶液时,加水量宜控制在6％以下。     

One‐pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalysed by Cupric Acetate under Solvent‐free Conditions

A solvent‐free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones from aromatic aldehydes, β‐keto ester/acetyl acetone and urea catalysed by cupric acetate under thermal condition is reported as a simple and an efficient protocol. Compared with classical Biginelli reaction reported in 1893, this new method provides much improved modification in terms of yield and reaction time. The usage of milder catalyst, environmental friendly procedures and excellent yields within a very short time (5–15 min) are the advantages of the method in which the involvement of solvent‐free condition adds an edge to the method. Thus, the efficiency of the protocol enabled the rapid synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one derivatives in a short duration.     

Raman spectroscopy of the acetates of sodium, potassium and magnesium at liquid nitrogen temperature

A comprehensive Raman spectroscopic study of the acetates of potassium, sodium and magnesium in the solid state have been made at both 298 and 77 K. Band separation of the C=O stretching region was not achieved in the 298 K spectra but was in the 77 K spectra. The CO stretching vibration is observed as a single band in both the 298 and 77 K spectra and its frequency is cation dependent. Single C–C stretching bands are observed for the acetates in the 77 K spectra. The OCO deformation vibrations were also cation dependent. Low frequency vibrations of magnesium acetate are observed at 338, 253 and 268 cm⁻¹ and are assigned to the MgO stretching vibration of the magnesium bisacetato complex. Low frequency bands were also observed for sodium acetate at 219, 277 and 288 cm⁻¹.     

Synthesis of new silica gel adsorbent anchored with macrocyclic receptors for specific recognition of cesium cation

In this article, a new class of silica gel adsorbent functionalized with macrocyclic receptors was developed for cesium recognition. A calixcrown molecule, with strong affinity to cesium cation, was decorated precisely at the 1,3-alternate benzene rings with reactive amino substituents, followed by the anchoring to the silica matrix to obtain a high functionalization degree. Structural characterization of the monomers and the organosilicas was carried out by ¹H/¹³C NMR, ²⁹Si/¹³C solid-state NMR, and FT-IR spectra. Besides, XPS survey, BET, TGA and ESEM were employed to investigate the surface property, thermal stability and micro-morphology of the organosilicas. Due to the host–guest interaction between the calixcrown receptor and cesium cation, efficient separation of cesium in the presence of competing alkali metals including sodium and potassium was realized. Mechanism regarding the recognition effect was discussed. The calixcrown-grafted organosilica material possesses the potential to be applied for the separation of cesium in radioactive liquid waste.     

The relationship between properties of fluorinated graphite intercalates and matrix composition 7

Inclusion compounds (intercalates) of fluorinated graphite matrix with ethyl acetate (C₂F_xBr_z·yCH₃COOC₂H₅, x = 0.49, 0.69, 0.87, 0.92, z = 0.01) were prepared by guest substitution from acetonitrile to ethyl acetate. The kinetics of the thermal decomposition (the first stage of filling → the second stage of filling) was studied under isothermal conditions at 291–307 K. The relationship of the host matrices’ structure with inclusion compounds’ thermal properties and kinetic parameters is discussed.     

An investigation of the thermal decomposition of gold acetate

The thermal decomposition characteristics of gold acetate to produce gold nanoparticles were investigated. A rapid and violent fragmentation of the gold acetate particles was observed at approximately 103±20°C when a rapid heating rate of 25°C min⁻¹ was used, leading to formation of nanosized spherical and partially coalesced gold particles. Particle size analysis was used to investigate possible relationships between the gold acetate crystallite size and the gold nanoparticles produced by thermal decomposition. The results indicate rapid (<0.14 ms) coalescence of the gold particles occurs for fragments in close proximity.     

EFFECTS OF DEOXYCORTICOSTERONE ACETATE ON MUSCLE ELECTROLYTES,RESTING POTENTIAL AND MITOCHONDRIA IN RATS

Deoxycorticosterone acetate, injected daily for 5, 10, 20 or 30 days, reduced the serum potassium levels of rats by about 25%, a decrease that was independent of the treatment period employed. Serum sodium concentrations were unchanged with treatment duration. The potassium concentrations in extensor digitorum longus (EDL) and soleus (SOL) muscles were significantly decreased, and those of sodium increased, after treatment. Accompanying these changes of electrolyte concentration, the resting membrane potentials of treated EDL and SOL were hyperpolarized in vivo, and showed depolarization with the decreases of external potassium concentrations in vitro. The mitochondria in the muscles of treated rats were damaged. The degree of damage was more serious in EDL than in SOL and was dependent on the duration of deoxycorticosterone acetate treatment.     

Far-infrared investigation of kaolinite and halloysite intercalates using terahertz time-domain spectroscopy

Two clay minerals from the kaolin group, namely well-ordered kaolinite and poorly ordered halloysite, were investigated by terahertz time-domain spectroscopy (THz-TDS). Both clay samples were used for preparation of their respective intercalates using dimethyl sulfoxide (DMSO) and potassium acetate (KAc) with water. The intercalates were also characterized by X-ray powder diffraction and Fourier transform infrared spectroscopy. The dielectric behaviour of clay samples was investigated in the far-infrared region of 0.2–2.7 THz corresponding to about 6.7–89.9 cm⁻¹. The frequency dependence of the power absorption coefficient revealed clear absorption bands for DMSO intercalates but not for KAc with water. For kaolinite – DMSO intercalate a distinct doublet at 1.70 THz (56.6 cm⁻¹) and 1.88 THz (62.6 cm⁻¹), and for halloysite – DMSO intercalate a single broad band centred around 1.72 THz (57.3 cm⁻¹) were found. These bands are reported for the first time in this type of intercalation substances and indicate the application potential of THz time-domain spectroscopy for use in the investigation and detection of chemical behaviour of molecular species introduced into the interlayer space of layered substances such as clays and clay minerals. Additionally, the qualitative characteristics of observed bands of DMSO intercalates in the THz region reasonably resembled the structural order/disorder of used kaolinite and halloysite samples.     

Stabilization of Cs/Re trapping filters using magnesium phosphate ceramics

The present study a promising method for stabilizing spent filters trapping cesium and technetium by using magnesium phosphate ceramics. Simulated spent filters were fabricated by vaporizing nonradioactive cesium and rhenium (a surrogate of Tc) through the voloxidizer. In order to reveal the characteristics of spent filters, phase structures and thermal stability were analyzed by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and thermogravimetric analysis techniques. Waste forms were fabricated by crushing spent filters and mixing them with magnesium oxide and potassium phosphate. Characterizations of the waste forms were performed by the analyses of compressive strength, apparent porosity, XRD, and scanning electron microscopy. The waste forms showed the excellent mechanical property compared with that of ordinary Portland cement, with the highest compressive strength of 38.1 MPa in the sample with 30 wt% of Cs-filter. Microstructural analysis suggests that waste materials are encapsulated by the binding matrix composed of magnesium potassium phosphate. The results of characterization suggest that fabricating a sound and durable waste form is possible with magnesium phosphate ceramics.     

2-取代-环戊烯酮及其衍生物的简易合成

本文报道以2-氯环戊酮的加成重排反应合成2-取代环戊酮。如再引入硫硫双键,则可合成2-取代环戊烯酮。取代环戊酮和取代环戊烯酮是合成药物和合成香料的重要中间体。     

Development and validation of a novel RP-HPLC method for stability-indicating assay of Abiraterone acetate

Abiraterone acetate is a prodrug of Abiraterone widely used for the treatment of metastatic castration resistant prostate cancer. In this study, a simple, sensitive, and rapid stability-indicating reverse phase HPLC method was developed and validated for the determination of Abiraterone acetate in bulk and its pharmaceutical formulation. The method was developed by HPLC using a Hypersil ODS C-18 (150 mm × 4.6 mm, 5 µm) column in a isocratic mode with mobile phase constituted by potassium phosphate buffer and acetonitrile (40:60, v/v%) flow rate was 1.0 mL min^?1, column temperature of 30°C, UV detection wavelength 235 nm, and injection volume of 20 µL. The validated parameters were in accordance with FDA and ICH specifications, assay exhibited a linear range of 25–250 µg mL^?1 with regression (r²) coefficient 0.9998. The limits of detection and quantification were 0.23 and 0.70 µg mL. Accuracy was between 99.34 and 100.07%. The drug was subjected to various stress conditions like acidic, base hydrolysis, oxidation, thermal, and photolytic degradation. Stress study Abiraterone acetate was found susceptible to degrade under hydrolytic (acid and base) conditions. The proposed method has stability indicating the resolution of the main peak from their degradation peaks. The validated method is suitable for quality control application and reduced analysis time.     

高取代度魔芋葡甘聚糖醋酸酯的制备及其热塑性和流变性研究

以魔芋葡甘聚糖(KGM)为原料,浓硫酸为催化剂,乙酸酐为改性剂,制备了KGM醋酸酯.研究了反应条件对KGM醋酸酯取代度(DS)的影响,KGM醋酸酯制备的最佳反应条件是乙醇∶水量比5∶5,反应时间2h,反应温度75℃,催化剂浓硫酸的浓度0.1mol/L,KGM与乙酸酐的量比5∶40(g/mL),取代度高达2.93,其分子量与KGM相比,则明显降低.运用傅立叶红外光谱仪(FTIR)、X射线衍射仪(XRD)、扫描电镜(SEM)、热重分析仪(TGA)、示差扫描量热仪(DSC)和旋转流变仪对KGM和高取代度KGM醋酸酯进行了表征.结果表明,KGM醋酸酯的羰基(CO)特征吸收峰较KGM明显增强,其表观形貌大部分为疏松絮状,KGM及其醋酸酯均为非晶态结构.与KGM相比,KGM醋酸酯的热稳定性下降,分解温度(Td)由KGM的261.10℃降低至KGM醋酸酯的204.56℃,KGM醋酸酯出现了明显的玻璃化转变,其玻璃化转变温度(Tg)为128.49℃.KGM醋酸酯是典型的黏弹性材料,其弹性比率占21.27%,其剪切黏度η对温度变化非常敏感,可通过温度的改变来调节KGM醋酸酯的加工流动性.KGM醋酸酯具有较好的热塑性.     

Copper ferrocyanide — polyurethane foam as a composite ion exchanger for removal of radioactive cesium

A method has been developed for the removal of cesium from the aqueous radioactive waste using a composite ion-exchanger consisting of Copper-Ferrocyanide Powder (CFC) and Polyurethane (PU) Foam. Polyvinyl acetate has been used as a binder in the preparation of CFC-PU foam. The physical properties of CFC such as density, surface area, IR stretching frequency and lattice parameters have been evaluated and also its potassium and copper(II) content have been estimated. Optimization of loading of CFC on PU foam has been studied. The CFC-PU was viewed under microscope to find out the homogeneity of distribution. Exchange capacities of the CFC-PU foam in different media have been determined and column studies have been carried out. Studies have been undertaken on extraction of cesium from CFC foam and also on digestion of spent CFC-PU foam and immobilization of digested solution in cement matrix. The cement matrices have been characterized with respect to density, bio-resistance and leaching resistance.     

The synthesis and characterization of poly(methylene terephthalate)

Poly(methylene terephthalate) (1GT) has been synthesized via the reaction of cesium or potassium terephthalates with dibromomethane or bromochloromethane in N-methylpyrrolidone at temperatures of 80–125°C. The polymerization was relatively slower with the latter substrate, though the potassium salt was found to be equally as efficient as its cesium counterpart with dibromomethane. The polymer is insoluble in all common polyester solvents, and its high molecular weight nature (DP _n ≥ 25) was inferred from elemental analyses and its fiber forming capacity. Thermal analyses indicated that 1GT possesses poor thermal stability and decomposes rapidly during melting, the initial process being thought to be the splitting out of formaldehyde. 1GT polymers were shown to contain a homologous series of cyclic oligomers (from dimer to decamer); the two most predominant were tentatively identified as the cyclic trimer and tetramer. No change in the cyclization efficiency was observed when the potassium counterion was substituted for cesium with Br CH₂ Br whereas a drastic reduction in the cyclic content was obtained using Br CH₂ Cl (with Cs⁺). The two most important features of the polymerization are the insensitivity of the reaction to the stoichiometric equivalence of the reactants and the production of reasonably high molecular weights at low conversions. It is suspected that the polymerization might be occurring through an interfacial mechanism.     

The thermal diffusion characteristics of hydrogen and alkali metal chlorides in aqueous-methanolic solutions at 298.15 K

The paper presents the results of experimental studies of thermoelectrochemical systems comprising silver chloride and quinhydrone electrodes in aqueous-methanolic solutions of hydrogen, lithium, potassium, and cesium chlorides. These results and literature data are used to calculate the standard entropies of transfer of electrolytes, Soret thermal diffusion coefficients, and entropies of moving ions at 298.15 K. The influence of the nature of electrolytes and mixed solvent composition on the characteristics of thermal diffusion transfer in the systems studied is discussed.     

SYNTHESIS OF POLY(VINYL ACETATE)-INTERCALATED GRAPHITE OXIDE BY AN IN SITU INTERCALATIVE POLYMERIZATION*

Graphite oxide, a pseudo-two-dimensional solid in bulk form, was synthesized from natural graphite powder byoxidization with KMnO_4 in concentrated H_2SO_4. The poly(vinyl acetate)-intercalated graphite oxide nano-composite wasprepared by an in situ intercalative polymerization reaction, in which n-octanol-graphite oxide intercalation compounds werefirst obtained, vinyl acetate monomer was then dispersed into the interlayer of modified graphite oxide, followed by thermalpolymerization of the monomer. It was experimentally shown that the c-axis space of poly(vinyl acetate)-intercalated graphiteoxide was increased to 0.115 nm, which suggested there existed a monolayer of poly(vinyl acetate) chain between the layersof graphite oxide. The nanocomposite was also characterized with thermal analysis and FT-IR spectrometry.     

Influence of gamma irradiation on the ageing characteristics of poly(ethylene-co-vinyl acetate) and poly(ethylene-co-vinyl acetate)/carbon black mixture

In this comparative study, the effect of gamma rays on the ageing characteristics of poly(ethylene-co-vinyl acetate) (EVA) and poly(ethylene-co-vinyl acetate)/carbon black mixture (EVA/CB) was investigated in terms of thermal stability. EVA, containing 13% vinyl acetate (VA), and EVA/CB, containing 13% VA and 1% carbon black (CB), were aged at 85°C in air up to 30 weeks for thermal ageing. Same substances were aged by means of UV light with a wavelength in the vicinity of 259 nm, in air, up to 400 h for UV ageing. Same substances were also irradiated with gamma rays at ambient conditions up to 400 kGy. Following these experiments, samples which had been irradiated with gamma rays, were subjected to thermal and UV ageing under the same conditions as for unirradiated samples. Dynamic thermogravimetry studies were performed for determination of the thermal stabilities of the samples. 10 and 50% mass losses were calculated for the samples from their respective curves. As a result of thermal analysis experiments, it was found that CB dramatically loses its protective property against thermal ageing of EVA after gamma irradiation. On the other hand, gamma irradiation does not have any significant effect on the UV ageing characteristics of EVA and EVA/CB in terms of thermal stability.     

Preparation of a New Polymeric Surfactant for Emulsion Polymerization

The stability of polymeric dispersions is a property of practical importance and hence, the search for an optimized strategy to equip polymer dispersions with sufficient stability is a matter of continuous research during the last years. The kernel is to reach a sufficient stability, as it is required during polymerization, conditioning, or storage and to allow coagulation or coalescence of particles when it is needed, such as during separation of polymer from latex or during film formation. In this study, the emulsion homopolymerization system containing vinyl acetate, potassium persulfate, new polymeric surfactant, NaHCO₃ and water was studied in the classical glass emulsion polymerization reactor. The effects of new polymeric emulsifier on the physicochemical properties of obtained vinyl acetate latex properties were investigated depending on vinyl acetate percentage in homopolymerization.