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1.
Batric Pesic Ph.D. Taili Zhou Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(6):42-45
Using ultrasound for the solvent extraction of gallium with Kelex 100 dramatically increased the rates (up to 15 times) of extraction in both artificial and real solutions. Among the modifiers, 2-undecanone performed the best; among the diluents, Escaid 200 produced the best results. With the application of ultrasound, temperature did not effect gallium extraction. Further, through the intermittent use of ultrasound, energy consumption can be decreased significantly. 相似文献
2.
Zhaoyue Liu Batric Pesic Krishnan S. Raja Raghu R. Rangaraju Mano Misra 《International Journal of Hydrogen Energy》2009
Highly ordered TiO2 nanotube arrays generate a considerable interest for hydrogen generation by an electrochemical photocell, since ordered architecture of nanotube arrays provides a unidirectional electric channel for electron's transport. Here, we report the hydrogen generation by highly ordered TiO2 nanotube arrays under actual sunlight in KOH electrolyte. The two-electrode electrochemical cell included an adjustable anode compartment capable of tracing the trajectory of the sun and a set of alkaline batteries connected with a rheostat for application of external bias. The results showed that the photocurrent responses of nanotube arrays match well with the intensity of solar irradiance on a clear summer day. Addition of ethylene glycol into KOH electrolyte as a hole scavenger enhanced the rate of hydrogen generation. A maximum photocurrent density of 31 mA/cm2 was observed at 13:30 h, by focusing the sunlight with an intensity of 113 mW/cm2 on the surface of the TiO2 nanotube arrays in 1 M KOH electrolyte with 10 vol% ethylene glycol under an applied bias of 0.5 V. The observed hydrogen generation rate was 4.4 mL/h cm2 under the focalized solar irradiance with an intensity between 104 mW/cm2 and 115 mW/cm2 from 10:00 to 14:20 h. 相似文献
3.
Several new chitosan derivatives were synthesized with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal-binding agents in aqueous environments. The ability of these derivatives to bind Cu2+, Pb2+, Cd2+, and Fe2+ was tested and compared to chitosan. Four of the new compounds, the products of the reaction of chitosan with mercaptosuccinic acid, thiirane, pyridoxal hydrochloride, and succinamide, show promising results as binding agents for the above metal ions. The compound with mercaptosuccinic acid bound twice as much Cd2+, five times as much Pb2+, and virtually no Fe2+ when compared to chitosan. The compound with thiirane bound three times as much Pb2+, whereas the pyridoxal hydrochloride derivative bound 30% more Cu2+ and twice the Pb2+. The succinamide derivative gave results comparable to chitosan, but with decreased solubility at low pH. © 1993 John Wiley & Sons, Inc. 相似文献
4.
Völler GH Krawczyk JM Pesic A Krawczyk B Nachtigall J Süssmuth RD 《Chembiochem : a European journal of chemical biology》2012,13(8):1174-1183
Lantibiotics are a large group of ribosomally synthesized peptides post-translationally modified to incorporate the amino acid lanthionine. They are classified, according to their biosynthetic pathway and bioactivity, into three major subtypes. Of Actinomycetes type III lantibiotics, only four peptides (SapB, SapT, LabA1, and LabA2) have been described and structurally characterized, although homologous gene clusters are abundant in other Actinomycetes. All these gene clusters share a similar architecture with a characteristic Ser/Ser/Cys motif in precursor peptides, which has previously been suggested to act as a precursor for lanthionine (SapB) and labionin (LabA2) rings. Mass spectrometry screening led to the discovery and characterization of three new representatives of type III lantibiotics: Avermipeptin (Avi), Erythreapeptin (Ery), and Griseopeptin (Gri) from Streptomyces avermitilis DSM 46492, Saccharopolyspora erythraea NRRL 2338, and Streptomyces griseus DSM 40236, respectively. Apart from the assignment of these peptides to their corresponding gene clusters, additional investigations on Avi, Ery and Gri peptides indicate stepwise leader processing by putative aminopeptidase-like protease(s), thus yielding mixtures of differently N-terminal-processed lantibiotic peptides. Similar peptide processing was observed for a heterologously expressed eryth biosynthetic gene cluster expressed in a Streptomyces host system. Remarkably, all isolates of the new type III lantibiotics contain both the amino acids lanthionine and labionin, thus implying dual-mode cyclase activity of the processing lyase-kinase-cyclase enzymes. These findings have implications for the structures and maturation of other type III lantibiotics from Actinomycetes. 相似文献
5.
Photoelectrochemical Cells: Carbon Nanotube–Graphitic Carbon Nitride Hybrid Films for Flavoenzyme‐Catalyzed Photoelectrochemical Cells (Adv. Funct. Mater. 24/2018) 下载免费PDF全文
6.
The dissolution of gold with elemental bromine was studied by using a rotating disc technique. The main parameters studied
were bromine and bromide concentrations, stirring speed, pH, and temperature. The effect of various salts, manganese, and
hydrogen peroxide was also examined. The dissolution kinetics of gold with Br2 and NaBr mixture is complex. The reaction mechanism is a function of solution composition, which determines the kind of adsorbing
species. For an excess concentration of bromide ions, the rate expression is Rate = (2k
cl7
k
al6)1/2
K
15 [Br
3
−
] and for an excess concentration of bromine, the rate expression is Rate = (2k
c27
k
a29)1/2 [Br−]1/2 {K25 [Br2]3/(1 +K
25 [Br2]3)}1/2
Gold in bromine solutions dissolves according to electrochemical/chemical (EC) mechanisms. The electrochemical component of
the mechanism is responsible for the formation of AuBr2. In the chemical component of the mechanism, this monovalent gold bromide disproportionates into gold and stable AuBr
4
−
, which reports into solution. With respect to pH, there are two characteristic dissolution regions. In the pH range of 1
to 7, gold dissolution rates were insensitive to pH. Above pH 7, gold dissolution rates decreased with increase of pH. 相似文献
7.
Osmokrovic P. Vujisic M. Cvetic J. Pesic M. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):803-812
This paper presents measurement results for the random variable "vacuum breakdown voltage", obtained by the application of pulse, dc, and ac voltage. Parameters varied during the measurements were: 1) vacuum pressure and 2) inter-electrode gap width. The measurements were performed under strictly controlled laboratory conditions. Conclusions about the influence that the variable parameters in the experiment exert on the parameters of theoretical statistical distributions have been drawn, based on the statistical analysis of the obtained experimental results. The obtained results have been explained by the mechanisms constituting the process of electrical breakdown in vacuum. 相似文献
8.
Darko GrujicicBatric Pesic 《Electrochimica acta》2002,47(18):2901-2912
The nucleation mechanisms of copper during electrodeposition of thin films from sulfate solutions were studied by utilizing the electrochemical techniques (cyclic voltammetry and chronoamperometry) and atomic force microscopy (AFM). Near atomically smooth glassy carbon was used as the deposition substrate (electrode). The copper nucleation mechanisms were examined as a function of solution pH, copper concentration, deposition potential, temperature, and background electrolyte. It was found that with pH and copper concentration increase, the nuclei size increased, while the nuclei population density decreased. An increase of deposition potential produced smaller nuclei and higher nuclei population density. Temperature affected the morphology of deposited copper. The presence of background electrolyte also influenced the morphology and population density of copper nuclei. The nucleation mechanisms were examined by fitting the experimental data (chronoamperometry) into the Scharifker-Hills nucleation models. It was found that at pH 1, in the absence of background electrolyte, copper nucleation was instantaneous. At pH 2 and 3, the mechanism was inconclusive. In the presence of background electrolyte, the mechanism at pH 1 and 2 was mixed, while at pH 3, the mechanism was progressive nucleation. 相似文献
9.
Application of ultrasound in extractive metallurgy: Sonochemical extraction of nickel 总被引:7,自引:0,他引:7
The importance of ultrasound in solvent extraction was examined by studying solvent extraction of nickel with Lix 65N and
Lix 70 extractants. The studied parameters were ultrasonic energy and frequency, pH, temperature, and organic and aqueous
solution composition. The stability of extractants under the influence of ultrasound was also examined. It was found that
ultrasound had a significant importance, because it increased the extraction rates four- to sevenfold. The effect of ultrasound
was physical,i.e., to increase the surface area. Ultrasonic energy consumption was also evaluated. The consumption was high, but it can be
significantly reduced by the appropriate method of application. A novel solvent extraction method, extraction-in-pipe, was
also proposed. 相似文献
10.
Mladen Pesic Josef Gruber Stephan Rampetzreiter Harald Witschnig Holger Arthaber 《国际射频与微波计算机辅助工程杂志》2019,29(7)
A method for measuring the resonance frequency of contactless chip cards is proposed in this article. Compared to the vector network analyzer (VNA) based state‐of‐the‐art method, the method gives a more accurate definition of resonance frequency, removes the subjectivity associated with the state‐of‐the‐art method, and makes the measurement integrable into ISO‐standardized test setups. Signal processing and system modeling are applied in order to determine the maximum active power in the chip card over a chosen frequency range. This is achieved by using a transfer function obtained from the model and by setting a chirp signal as input to the system. The determined maximum of active power is mapped to the corresponding frequency in the chirp signal, which is defined as the resonance frequency. The proposed method is verified by simulations and by comparing measurement results with the state‐of‐the‐art. The results show that the proposed method offers significant advantages over the state‐of‐the‐art method. 相似文献