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1.
A. V. Artemov V. A. Bul’ba S. A. Voshchinin Yu. A. Krutyakov A. A. Kudrinskii I. I. Ostryi A. V. Pereslavtsev 《Russian Journal of General Chemistry》2012,82(4):801-807
The plasma technology provides the possibility to prevent hazardous industrial waste formation. Moreover, it is reasonable to include into the pyrogas treatment technology the catalytic stages of steam and carbon dioxide reforming and Fischer-Tropsch hydrocarbon synthesis. Plasma technology allows waste to serve as an inexhaustible source of raw materials for production of electricity, hydrogen, and fuels. 相似文献
2.
Glucose oxidase (GOD) and Horseradish peroxidase (HRP) were covalently coupled to alkylamine controlled pore glass by means of glutaraldehyde. About 700-800 U/g of immobilized GOD and 300-400 U/g of immobilized HRP were obtained. Some factors of affecting enzyme immobilization were discussed. The immobilized enzymes were packed into a plastic tube and used in flow-injection analysis (FIA) for glucose in serum. A good linearity range was observed for this immobilized enzyme system at 20 mg/mL to 1000 mg/dL D-glucose, the recovery was 95.4-103.5%, the within-batch imprecision was 0.8-2.2%, and the between-batch imprecision was 2.2-4.2%. More than 100 samples were measured within an hour. One enzyme column with five units of immobilized GOD and HRP, applied for 50 assays/d, has been used for more than 2 mo. 相似文献
3.
Bhupendra K. Soni Robert L. Kelley Vipul J. Srivastava 《Applied biochemistry and biotechnology》1998,74(2):115-123
A two-stage process for the manufacture of propylene oxide is described. The preliminary economics based on use of methanol
as a regeneration factor has resulted in a production cost of $12.10/lb of propylene oxide based on propylene oxide production
rate of 40 mg/g-cell/h in conventional reactor. Increasing the propylene oxide production from 40 to 500 mg/g-cell/h resulted
in a cost reduction from $12.10 to 5.8/lb of propylene oxide. The granular-activated, carbon-fluidized bed reactor (GAC-FBR)
absorbs the propylene oxide and when saturated is eluted with ethyl acetate, and the bed is regenerated by steam to drive
off the residual solvents. The estimated manufacturing costs are approx 59% lower (from $12.10/lb in conventional reactors
to $5.00/lb for GAC-FBRs) for products that are highly inhibitory such as epoxides. In the GAC-FBR reactor, enhancing the
propylene oxide production rate from 120 to 1500 mg/gcell/h has resulted in the cost reduction to $2.00/lb. Enhancing the
production capacity from 1 million lb to 10 million lb/yr has further reduced the cost of production to $1.00/lb.
This article is reprinted from the Symposium issue of ABAB entitled “Biotechnology for Fuels and Chemicals: Proceedings of
the Nineteenth Symposium of Biotechnology for Fuels and Chemicals” (pp. 651–659). Figures and captions are correct as they
now appear. 相似文献
4.
Soni Bhupendra K. Kelley Robert L. Srivastava Vipul J. 《Applied biochemistry and biotechnology》1998,(1):651-659
A two-stage process for the manufacture of propylene oxide is described. The preliminary economics based on use of methanol
as a regeneration factor has resulted in a production cost of $12.10/lb of propylene oxide based on propylene oxide production
rate of 40 mg/g-cell/h in conventional reactor. Increasing the propylene oxide production from 40 to 500 mg/g-cell/h resulted
in a cost reduction from $12.10 to 5.8/lb of propylene oxide. The granular-activated, carbon-fluidized bed reactor (GAC-FBR)
absorbs the propylene oxide and when saturated is eluted with ethyl acetate, and the bed is regenerated by steam to drive
off the residual solvents. The estimated manufacturing costs are approx 59% lower (from $12.10/lb in conventional reactors
to $5.00/lb for GAC-FBRs) for products that are highly inhibitory such as epoxides. In the GAC-FBR reactor, enhancing the
propylene oxide production rate from 120 to 1500 mg/g-cell/h has resulted in the cost reduction to $2.00/lb. Enhancing the
production capacity from 1 million lb to 10 million lb/yr has further reduced the cost of production to $1.00/lb. 相似文献
5.
Naturally Occurring Radioactive Materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. In this paper the analytical methods to determine the chemical and radiochemical composition of a solid waste generated in an acid phosphoric production plant was shown. The sample, analysed by gamma spectrometry and radiochemical methods, contained 210Pb and 210Po and a high activity concentration of uranium isotopes but it shows a very low quantity of 226Ra. Also a sequential extraction method consisting of five operationally-defined fractions was used to evaluate the leachability of uranium isotopes, 210Pb and 210Po. The average leaching potential observed in the sample is 97.6% for 238U, 93.2% for 210Pb and 82.4% for 210Po. Moreover the results show that 210Pb and 210Po are leachable under only extreme conditions, whereas uranium is very more soluble. 相似文献
6.
The Waste Extraction Test (WET) is used in California as a complement to the Toxicity Characteristic Leaching Procedure (TCLP). The WET protocol consists of shaking a sample with citrate buffer and determining the metal content in the solution produced. This procedure requires a 1-to-10 waste-to-liquid ratio and 48 h for extraction. Although the WET protocol proves to be very useful, it is a time-consuming step in the determination of leaching and mobility. Therefore, a microwave extraction procedure was optimized to emulate the relative extraction efficiency obtained by the WET protocol. Lead, arsenic, and copper concentrations were measured by inductively coupled plasma mass or atomic spectrometry (ICP-MS or ICP-AES), following a strict quality assurance protocol. Results obtained with this new methodology were statistically comparable to those obtained by the WET protocol. This microwave extraction approach proved simple and fast, reducing sample treatment by almost 280%. A significant reduction also occurs in waste production, materials, labor, and chemical usage. Therefore, the microwave extraction procedure is recommended as a rapid and cost effective monitoring tool for waste samples when combined with or supplemented by the traditional WET protocol. 相似文献
7.
A. A. Guliev A. E. Smolyar I. A. Abronin V. P. Litvinov 《Theoretical and Experimental Chemistry》1993,28(2):119-121
The semiempirical method SCF MO LCAO in the CNDO/S valence approximation is used to study thiotetramethylselenofulvalene (TMTSF)2 dimers. Band structure parameters are calculated for (TMTSF)2PF6.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 2, pp. 136–139, March–April, 1992. 相似文献
8.
9.
A variety of thioamides and thioureas are rapidly transformed to their oxo derivatives with Bi(NO3)3·5H2O in excellent yields. However, thiono esters and thioketones are converted to their corresponding carbonyl compounds in only poor yields. Bi(NO3)3·5H2O is relatively non-toxic, insensitive to air and inexpensive. These features coupled with the selective deprotection of thioamides and thioureas in the presence of thiono esters and thioketones make this method an attractive alternative to the existing routes for deprotection of thiocarbonyl compounds. 相似文献
10.
Molecular orbital calculations were performed to obtain electron density and electric field gradient at the iron nucleus of iron carbonyls Fe(CO)n (n=2–5) so as to estimate the Mössbauer parameters, of these species. The calculated values were compared with the experimental values obtained in low temperature nitrogen matrices; structures of these species were optimized to fit the observed values. 相似文献
11.
Richelle M Darimont C Piguet-Welsch C Fay LB 《Rapid communications in mass spectrometry : RCM》2004,18(7):795-798
This paper presents a high-throughput method for the simultaneous determination of deuterium and oxygen-18 (18O) enrichment of water samples isolated from blood. This analytical method enables rapid and simple determination of these enrichments of microgram quantities of water. Water is converted into hydrogen and carbon monoxide gases by the use of a high-temperature conversion elemental analyzer (TC-EA), that are then transferred on-line into the isotope ratio mass spectrometer. Accuracy determined with the standard light Antartic precipitation (SLAP) and Greenland ice sheet precipitation (GISP) is reliable for deuterium and 18O enrichments. The range of linearity is from 0 up to 0.09 atom percent excess (APE, i.e. -78 up to 5725 delta per mil (dpm)) for deuterium enrichment and from 0 up to 0.17 APE (-11 up to 890 dpm) for 18O enrichment. Memory effects do exist but can be avoided by analyzing the biological samples in quintuplet. This method allows the determination of 1440 samples per week, i.e. 288 biological samples per week. 相似文献
12.
Summary A study has been made of the high-temperature reactions taking place in the graphite matrix of a d. c. carbon arc. A special evaporator was used for controlled heating of samples. Volatilisations were investigated spectrographically, and X-ray diffraction was used for detection of any new phases formed. The presence of sodium fluoride or chloride was found to enhance the volatilisation of the elements investigated, but no evidence was found for formation of their fluorides or chlorides.
Zusammenfassung Die in der Graphitmatrix eines Gleichstrombogens bei hohen Temperaturen stattfindenden Reaktionen wurden untersucht. Ein spezieller Verdampfer wurde für das kontrollierte Erhitzen der Proben verwendet. Verflüchtigungen wurden spektrographisch festgestellt, zum Nachweis etwa neu entstandener Phasen diente die Röntgendiffraktion. Die Anwesenheit von NaF oder NaCl begünstigt die Verflüchtigung der untersuchten Elemente, ohne daß Anzeichen für die Bildung ihrer Fluoride oder Chloride gefunden werden konnten.相似文献
13.
14.
K. E. Anders Ohlsson 《Accreditation and quality assurance》2012,17(3):301-313
Measurement uncertainties evaluated according to GUM were given in an uncertainty budget for the measurement of mass fractions of 12 elements in conifer tree needle materials. The measurement was performed using ICP-AES, with prior microwave digestion of the dried sample material. The uncertainty budget for Ca as an example showed that correction for a systematic error was the main source of measurement uncertainty. The key to reduced measurement uncertainty therefore lies in identifying the main sources of systematic errors, and reducing the uncertainty associated with their correction. The usefulness of the uncertainty budget was demonstrated in its application to method validation, to the design of a quality control program, and finally for guiding method optimization. 相似文献
15.
To test the feasibility of the guanidinate architecture for the support of boron(i) carbene analogues the energy gap between the singlet and triplet states of the model compound, [Me(2)NC{N(Ph)}(2)B:] (), has been probed by both DFT and second order M?ller-Plesset (MP2) methods. The singlet state is calculated to be more stable than the triplet state by between 6.0 and 10.1 kcal mol(-1). The new (guanidinate)boron dichlorides [Ph(2)NC{N(Mes)(2)]BCl(2) () and [Ph(2)NC{N(Dipp)(2)]BCl(2) () have been prepared and characterized by single-crystal X-ray diffraction. Attempts to reduce and to the corresponding boron(i) species were not successful. 相似文献
16.
Our previously defined Sparkle model (Inorg. Chem. 2004, 43, 2346) has been reparameterized for Eu(III) as well as newly parameterized for Gd(III) and Tb(III). The parameterizations have been carried out in a much more extensive manner, aimed at producing a new, more accurate model called Sparkle/AM1, mainly for the vast majority of all Eu(III), Gd(III), and Tb(III) complexes, which possess oxygen or nitrogen as coordinating atoms. All such complexes, which comprise 80% of all geometries present in the Cambridge Structural Database for each of the three ions, were classified into seven groups. These were regarded as a "basis" of chemical ambiance around a lanthanide, which could span the various types of ligand environments the lanthanide ion could be subjected to in any arbitrary complex where the lanthanide ion is coordinated to nitrogen or oxygen atoms. From these seven groups, 15 complexes were selected, which were defined as the parameterization set and then were used with a numerical multidimensional nonlinear optimization to find the best parameter set for reproducing chemical properties. The new parameterizations yielded an unsigned mean error for all interatomic distances between the Eu(III) ion and the ligand atoms of the first sphere of coordination (for the 96 complexes considered in the present paper) of 0.09 A, an improvement over the value of 0.28 A for the previous model and the value of 0.68 A for the first model (Chem. Phys. Lett. 1994, 227, 349). Similar accuracies have been achieved for Gd(III) (0.07 A, 70 complexes) and Tb(III) (0.07 A, 42 complexes). Qualitative improvements have been obtained as well; nitrates now coordinate correctly as bidentate ligands. The results, therefore, indicate that Eu(III), Gd(III), and Tb(III) Sparkle/AM1 calculations possess geometry prediction accuracies for lanthanide complexes with oxygen or nitrogen atoms in the coordination polyhedron that are competitive with present day ab initio/effective core potential calculations, while being hundreds of times faster. 相似文献
17.
I.B. Brenner A.E. Watson T.W. Steele E.A. Jones M. Goncalves 《Spectrochimica Acta Part B: Atomic Spectroscopy》1981,36(8):785-797
An account is given of the development of a procedure for the determination of the rare earth (RE) elements in a large variety of geological materials employing a medium power argon-nitrogen ICP coupled with a 3.4m Ebert spectrograph. The effects of the carrier and intermediate gas flow rates, height of observation and power on RE spectral line intensities have been studied. The line-to-background ratio of the RE analyte was found to increase with observation height and passed through a maximum at 12–14 mm above the top of the work coil. The method eventually developed allows the direct determination of the lanthanides and yttrium at the 50–200 μg g?1 levels using a single solution prepared by fusing 0.2–1 g samples with Na2O2 or LiBO2 and dissolving the melt in 4–10% (v/v) HNO3, or by treating the samples with HF-HClO4-HNO3 mixtures. For lower contents of the RE elements, they can be separated from matrix concomitants by ion exchange employing AG50W-X8 resin. A large variety of silicate and phosphate reference materials was analysed using scandium as the internal standard. The relative standard deviations vary from about 1.5–15%. No matrix effects were observed despite the large compositional variation of the samples analysed. 相似文献
18.
Summary Frictional coefficients between membrane matrix and permeants have been evaluated for ThO2/DMF system. The degrees of coupling q and the maximum value of the efficiencies of electrokinetic energy conversion, max, for both the modes of conversion, viz., electro-osmotic flow and streaming potential have been calculated from these coefficients and the results have been found to be in accordance with non-equilibrium thermodynamic theories. The values of frictional coefficients have also been used for characterising the membrane, viz., in determining the equivalent pore radii and the number of pores.With 2 tables 相似文献
19.
Excitation functions fornatZn (p, xn) and (p, pxn) nuclear reactions in the 5–45 MeV proton energy range were measured. Evaluations were made both of
target thickness and proton energy in order to optimize the67Ga production rate, at the same time minimizing contamination by the66Ga. Optimal irradiation conditions, depending both on the beam current available and on the power dissipated into the target
were determined. 相似文献
20.
Organocyanamides, Ntbd1;CNR(2) (R = Me or Et), react with trans-[Mo(N(2))(2)(dppe)(2)] (1, dppe = Ph(2)PCH(2)CH(2)PPh(2)), in THF, to give the first mixed molybdenum dinitrogen-cyanamide complexes trans-[Mo(N(2))(NCNR(2))(dppe)(2)] (R = Me 2a or Et 2b) which are selectively protonated at N(2) by HBF(4) to yield the hydrazide(2-) complexes trans-[Mo(NNH(2))(NCNR(2))(dppe)(2)][BF(4)](2) (R = Me, 3a, or Et, 3b). On treatment with Ag[BF(4)], oxidation and metal fluorination occur, and the ligating cyanamide undergoes an unprecedented beta-protonation at the unsaturated C atom to form trans-[MoF(NCHNR(2))(dppe)(2)][BF(4)](2) (R = Me, 4a, or Et, 4b) compounds which present the novel amidoazavinylidene (or amidomethyleneamide) ligands. Complexes 4 are also formed from the corresponding compounds 3, with liberation of ammonia and hydrazine. The crystal structure of 2b was determined by single-crystal X-ray diffraction analysis which indicates that the N atom of the amide group has a trigonal planar geometry. 相似文献