土壤环境中铅的化学

论述了环境中铅的背景值、来源、污染、质量标准、化学循环以及环境中铅的烷基化，为铅污染治理提供理论依据。     

Thermodynamic investigation of zirconium diselenite

Summary On the basis of calorimetric research of selenium dioxide, zirconium dioxide and zirconium diselenite dissolution reactions in the hydrofluoric acid solution under 298 K a standard enthalpy of Zr(SeO₃)₂ formation reaction from ZrO₂ and SeO₂ and a standard enthalpy of zirconium diselenite formation have been obtained. The value of enthalpy has been equal to -58.1±3.43 kJ mol^-1 in ZrO_2(solid)+2SeO_2(solid) Zr(SeO₃)_2(solid) reaction. The standard enthalpy of zirconium diselenite formation is equal to H_f,298⁰Zr(SeO₃)_2(solid)= -1603.2±3.8 kJ mol^-1. The H_f,298⁰ Zr(SeO₃)_2(solid) value has been determined for the first time.     

Organomineral sorbents based on clinoptilolite-containing tuffs

The anion-exchange properties of a new organomineral sorbent obtained by modification of clinoptilolite-containing tuffs by polyhexamethyleneguanidine have been studied after different periods of storage (time after synthesis) and numbers of sorption-regeneration cycles. The sorbent can be used as a cation- and an anion-exchanger simultaneously. Selectivity coefficients (exchange constants) for F^–, SO₄ ^2–, and HPO₄ ^2– ionsvs. Cl^– ions on modified clinoptilolite-containing tuffs have been determined. The modification improves the mechanical properties of clinoptilolite tuffs.For part 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1554–1556, September, 1994.     

Blood lead monitoring in Italy: Assessment of the quality of results obtained between 1992 and 1994

Between 1992 and 1994, a new screening campaign for blood Pb monitoring in the Italian general population was carried out. Since the first campaign (started in 1978, in accomplishment of the European Community Directive 77/312/EEC) a working group of the Laboratory of Clinical Biochemistry at the Italian National Institute of Health (Istituto Superiore di Sanità), as the Reference Centre (RC), has coordinated the activity of various laboratories spread over the national territory. Appropriate quality assurance procedures, including an external quality assessment scheme (EQAS), were elaborated. Within the EQAS, three or four trials were carried out every year. Each laboratory participating in the trial analyzed eight control samples prepared from cow blood at different Pb concentrations. The results obtained by each peripheral laboratory and the RC between 1992 and 1994 have been compared by regression analysis. The same statistical method was adopted to compare the results obtained by each peripheral laboratory and the RC in the duplicate analysis of about 10 per cent of the human samples collected during the 1992–1994 monitoring campaign. There was no evidence of systematic differences between the regression lines obtained on control and human samples. In spite of the lower Pb concentration in the control samples analyzed during the 1992–1994 campaign, the analytical performance of the laboratories was better than that obtained in the previous screening campaign (1985–1986). Blood Pb levels observed in human samples collected between 1992 and 1994, confirm the downward time trend observed in the campaigns carried out in 1978–1979, 1980–1981 and 1985–1986. This study confirms that the results obtained in an EQAS are representative of the actual performance in the analysis of real (human) samples.     

Enhanced visible light photocatalytic activity of CeO2@Zn0.5Cd0.5S by facile Ce(IV)/Ce(III) cycle

In this study, CeO₂@Zn_0.5Cd_0.5S heterostructure (Ce@ZCS) is synthesized via a simple two-step hydrothermal method. The effect of CeO₂ loading on the visible-light photoactivity of Zn_0.5Cd_0.5S is mainly investigated. It is found that Ce@ZCS shows a 1.9 times activity as high as ZCS for the MB degradation. The improved activity mainly results from the significant enhanced charge separation by CeO₂, in which the electron transfer is obviously promoted by the facile Ce(IV)/Ce(III) cycle. The excited electrons of ZCS is easy to transfer to CeO₂, thus obviously increasing the charge separation of ZCS. The accepted electrons by CeO₂ may easily be captured by the adsorbed O₂ to form O₂⁻, and then O₂⁻ could combine with H⁺/H₂O to form HO₂, and OH. Finally, O₂⁻, h⁺ and OH are confirmed as the major oxidative species in photocatalytic reaction for Ce@ZCS, and a possible photocatalytic mechanism is proposed. The cheap, efficient Ce@ZCS photocatalyst could be applied for practical waste water treatment.     

Effects of glucose,glutamine, and malate on the metabolism of spodoptera frugiperda clone 9 (sf9) cells

Optimal design and operation of bioreactors for insect cell culture is facilitated by functional relations providing quantitative information on cellular metabolite consumption kinetics, as well as on the specific cell growth rates (μ_G). Initial specific consumption rates of glucose, malate, and oxygen, and associated changes in μ_G, were measured forSpodoptera frugiperda clone 9 (Sf9) cells grown in batch suspension culture in medium containing 7–35 mM glucose, 0–16 mM malate, and 4–16 mM glutamine. The initial specific glucose consumption rate (q _G ) could be described by a modified Michaelis-Menten equation treating malate as a “competitive” inhibitorK ₁ = 6.5 mM) and glutamine as a “noncompetitive” inhibitorK _I = 14 mM) ofq _G , with aK _m of 7.1 mM for glucose. All three carbon sources were found to increase μ_G in a saturable manner, and a modified Monod equation was employed to describe this relationship (μ_Gmax = 0.047 h^-1). The initial specific oxygen consumption rate (q_O2) in Sf9 cells could be related to μ_G by the maintenance energy model, and it was calculated that, under typical culture conditions, about 15–20% of the cellular energy demand comes from functions not related to growth. Fitted parameters in mathematical expression for μg: K₄, Monod constant for glucose (mM); K₅, modified Monod constant for malate (mM); K₆, Monod constant for glutamine (mM); m_o2, specific consumption rate of oxygen by the cells under zero-growth conditions (nmol/cell/h); q_F, initial specific fumarate production rate (nmol/cell/ h);q _G , initial specific glucose consumption rate (nmol/cell/h); q_Gmax, maximum initial specific glucose consumption rate (nmol/cell/h);q _M , initial specific malate consumption rate (nmol/cell/h); q_o2, initial specific oxygen consumption rate (nmol/cell/h); Y_o2, cell yield on oxygen (cells/nmol); μ, initial specific cell growth rate (h^-1); μ_g, initial specific cell growth rate (h^-1); μG_max, maximum initial specific cell growth rate (h^-1).     

A simultaneous TG–DTA study of the thermal decomposition of 2-hydroxybenzoic acid, 2-carboxyphenyl ester (salsalate)

Simultaneous thermogravimetry–differential thermal analysis (TG–DTA) and gas and liquid chromatography with mass spectrometry detection have been used to study the kinetics and decomposition of 2-hydroxybenzoic acid, 2-carboxyphenyl ester, commercially known as salsalate. Samples of salsalate were heated in the TG–DTA apparatus in an inert atmosphere (100 ml min⁻¹ nitrogen) in the temperature range 30–500 °C. The data indicated that the decomposition of salsalate is a two-stage process. The first decomposition stage (150–250 °C) had a best fit with second-order kinetics with E_a=191–198 kJ/mol. The second decomposition stage (300–400 °C) is described as a zero-order process with E_a=72–80 kJ/mol. The products of the decomposition were investigated in two ways:

(a)Salsalate was heated in a gas chromatograph at various isothermal temperatures in the range 150–280 °C, and the exit gas stream analyzed by mass spectrometry (GC–MS). This approach suggested that salsalate decomposes with the formation of salicylic acid, phenol, phenyl salicylate, and cyclic oligomers of salicylic acid di- and tri-salicylides.

(b)One gram samples of salsalate were heated in a vessel under nitrogen to 150 °C, and the residues were analyzed by liquid chromatography–mass spectrometry (LC–MS). The major compound detected was a linear tetrameric salicylate ester.

     

The circular chemistry conceptual framework: A way forward to sustainability in industry 4.0

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热致型液晶聚合物的近晶相结构研究

本文借助于不同热处理样品的WAXD研究和变温FTIR分析,从液晶态与结晶态面间距的变化,晶态、液晶态和各向同性液态下结构构象的差异出发,研究了聚合物液晶态下的近晶相结构模型。     

The standard enthalpies of formation of some dibenzoannelated cycloalkanols

The heats of combustion of trans-9,10-bis-hydroxymethyl-9,10-dihydrophenanthrene, trans-5-hydroxymethyl-5,6-dihydro-7H-dibenzo[a,c]cyclohepten-6-ol, 5-hydroxymethyl-5,6-dihydro-7H-di-benzo[a,c]cycloheptene, 6-hydroxymethyl-5,6-dihydro-7H-dibenzo[a,c]cycloheptene, 5H-dibenzo-[a,d]cyclohepten-5-ol and 5H-10,11-dihydrodibenzo[a,d]cyclohepten-5-ol were measured by means of a Gallenkamp adiabatic bomb calorimeter. Uncertainties in the determination of the heats of combustion ranged between 0.2 and 0.3%. The enthalpies of formation and atomization for the six compounds were derived. The experimental values of the heats of atomization were compared with those calculated using the Allen–Skinner bond energy scheme. Conclusions about energetic contributions which stabilize the structure of the investigated compounds were drawn.