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1.
p-Aminothiophenol (PATP) and humic acids (HA or HAs) were applied jointly as the electron transfer accelerants of redox reactions
of cytochrome c (Cyt c) on gold electrodes. The electrochemical properties of the modified electrodes were studied by field emission scanning electron
microscope, ultraviolet-visible spectroscopy, electrochemical impedance spectroscopy, Raman spectroscopy and cyclic voltammetry.
The immobilized Cyt c displayed a couple of stable and well-defined redox peaks with a formal potential of −0.101 V (vs. SCE) in pH 7.0 phosphate
buffer solution. Cyt c adsorption is in the form of a monolayer with average surface coverage of 5.28 pmol cm−2. The electron transfer rate constant was calculated to be 2.14 s−1. It indicate that the HA film acted as a good adsorption matrix for Cyt c and an excellent accelerant for the redox of Cyt c. The Cyt c-HA modified gold electrode showed a new couple of well-marked redox peaks when 2,4-dichlorophenol was added to the test solution. 相似文献
2.
Valduga E Valério A Treichel H Furigo Júnior A Di Luccio M 《Applied biochemistry and biotechnology》2009,157(1):61-69
With the objective of determining the kinetic behavior (growth, substrate, pH, and carotenoid production) and obtain the stoichiometric
parameters of the fermentative process by Sporidiobolus salmonicolor in synthetic and agroindustrial media, fermentations were carried out in shaken flasks at 25°C, 180 rpm, and initial pH of
4.0 for 120 h in the dark, sampling every 6 h. The maximum concentrations of total carotenoids in synthetic (913 μg/L) and
agroindustrial (502 μg/L) media were attained approximately 100 h after the start of the fermentative process. Carotenoid
bioproduction is associated with cell growth and the ratio between carotenoid production and cell growth (Y
P/X) is 176 and 163 μg/g in the synthetic and agroindustrial media, respectively. The pH of the agroindustrial fermentation medium
varied from 4.2 to 8.5 during the fermentation. The specific growth rate (μ
X) for S. salmonicolor in synthetic and agroindustrial media was 0.07 and 0.04 h−1, respectively. The synthetic medium allowed for greater productivity, obtaining maximum cell productivity (P
x) of 0.08 g L−1 h−1 and maximum total carotenoid productivity (P
car) of 14.2 μg L−1 h−1. Knowledge of the kinetics of a fermentative process is of extreme importance when transposing a laboratory experiment to
an industrial scale, as well as making a quantitative comparison between different culture conditions. 相似文献
3.
T. López E. Ortiz R. Gómez M. Picquart 《Journal of Sol-Gel Science and Technology》2006,37(3):189-193
Samples of amorphous sol-gel titania were prepared at 50%wt with tungstophosphoric or molybdophosphoric acid. The resulting
gels were dried and annealed at 100, 150 and 200°C and studied by FT-IR, UV-Vis, EPR, TGA and Raman spectroscopy. By FT-IR
the evolution of the stretching vibration of the OH groups (3450–3700 cm−1) was followed. The intensity of this band decreased as the annealing temperature increased. With UV-Vis spectroscopy the
band gap was determined for each sample, and the Eg was found between 2.72 and 3.38 eV. Raman spectroscopy revealed the formation
of Mo—O—Ti and W—O—Ti—O bonds. An intense EPR signal at g = 1.998 was observed during annealing of the samples. Amorphous solids with a significant number of vacancies and promising
photocatalytic properties were obtained. 相似文献
4.
M. Prabu S. Selvasekarapandian M. V. Reddy B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2012,16(5):1833-1839
Olivine-structured LiCoPO4 is synthesized by a Pechini-type polymer precursor method. The structure and the morphology of the compounds are studied
by the Rietveld-refined X-ray diffraction, scanning electron microscopy, Brunauer, Emmett, and Teller surface area technique,
infrared spectroscopy, and Raman spectroscopy techniques, respectively. The ionic conductivity (σ ionic), dielectric, and electric modulus properties of LiCoPO4 are investigated on sintered pellets by impedance spectroscopy in the temperature range, 27–50 °C. The σ (ionic) values at 27 and 50 °C are 8.8 × 10−8 and 49 × 10−8 S cm−1, respectively with an energy of activation (E
a) = 0.43 eV. The electric modulus studies suggest the presence of non-Debye type of relaxation. Preliminary charge–discharge
cycling data are presented. 相似文献
5.
Highly concentrated alkaline gallate solutions with 0.23≤[Ga(III)]T≤2.32 mol⋅dm−3 and 1≤[NaOH]T≤15 mol⋅dm−3 have been prepared and investigated by Raman and 71Ga-NMR spectroscopy. Both the Raman and 71Ga-NMR spectra are consistent with the presence of only one Ga-bearing species in these solutions, the tetrahedral hydroxocomplex,
Ga(OH)4−. Contact ion pairs were found to cause variations in the Raman and 71Ga-NMR parameters that are at the edge of detectability. Other species that have been claimed to exist in the literature,
like higher hydroxo complexes (i.e., Ga(OH)63−) or the μ-oxo-bridged dimer (i.e., (OH)3Ga-O-(OH)32−), were not detected by these spectroscopic techniques. If such solution species exist at all, their concentrations are below
the detection limit of Raman and 71Ga-NMR spectroscopy. The behavior of gallium appears to be very similar to that of aluminium under identical conditions, except
that the dimeric species detected in aluminate solutions is undetectable in analogous gallates. 相似文献
6.
A novel chlorine-doped titanium dioxide catalyst with visible light response was prepared by hydrolysis of tetrabutyl titanate
in hydrochloric acid. The catalyst samples were characterized by X-ray diffraction (XRD), transmission electron microscopy
(TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Results
showed that the doped element of Cl lowered the temperatures of phase transformation of TiO2 from amorphous to anatase and from anatase to rutile. The absorption edge of chlorine-doped TiO2 calcined at 300°C shifted to visible light region. X-ray photoelectron spectroscopy results proved that chlorine existed
in the TiO2 crystal lattice as anion. The photocatalytic degradation of phenol showed that under visible light (λ > 400 nm) irradiation, the chlorine-doped TiO2 calcined at 300°C displayed the best performance, the degradation ratio of phenol was 42.5% after 120 min.
Translated from Chinese Journal of Catalysis, 2006, 27(10): 890–894 [译自: 催化学报] 相似文献
7.
Alexander Konkin Frank Wendler Frank Meister Hans-Klaus Roth Albert Aganov Oliver Ambacher 《Cellulose (London, England)》2007,14(5):457-468
Degradation processes of N-methylmorpholine-N-oxide monohydrate (NMMO), cellulose and cellulose/NMMO solutions were studied by high performance liquid chromatography (HPLC)
and electron spin resonance (ESR) spectroscopy. Kinetics of radical accumulation processes under UV (λ = 248 nm) excimer laser
flash photolysis was investigated by ESR at 77 K. Beside radical products of cellulose generated and stabilized at low temperature,
radicals in NMMO and cellulose/NMMO solutions were studied for the first time in those systems and attributed to nitroxide
type radicals ∼CH2–NO•–CH2∼ and/or ∼CH2–NO•–CH3∼ at the first and methyl •CH3 and formyl •CHO radicals at the second step of the photo-induced reaction. Kinetic study of radicals revealed that formation and recombination
rates of radical reaction depend on cellulose concentration in cellulose/NMMO solutions and additional ingredients, e.g.,
Fe(II) and propyl gallate. HPLC measurements showed that the concentrations of ring degradation products, e.g., aminoethanol
and acetaldehyde, are determined by the composition of the cellulose/NMMO solution. Results based on HPLC are mainly maintained
by ESR that supports the assumption concerning a radical initiated ring-opening of NMMO. 相似文献
8.
The adsorption and activation of NO molecules on Cu-ZSM-5 catalysts with different Cu/Al and Si/Al ratios (from 0.05 to 1.4 and from 17 to 45, respectively) subjected to different pretreatment was studied by ultraviolet-visible diffuse reflectance (UV-Vis DR). It was found that the amount of chemisorbed NO and the catalyst activity in NO decomposition increased with an increase in the Cu/Al ratio to 0.35–0.40. The intensity of absorption bands at 18400 and 25600 cm−1 in the UV-Vis DR spectra increased symbatically. It was hypothesized that the adsorption of NO occurs at Cu+ ions localized in chain copper oxide structures with the formation of mono- and dinitrosyl Cu(I) complexes, and this process is accompanied by the Cu2+...Cu+ intervalence transfer band in the region of 18400 cm−1. The low-temperature activation of NO occurs through the conversion of the dinitrosyl Cu(I) complex into the π-radical anion (N2O2)− stabilized at the Cu2+ ion of the chain structure, [Cu2+-cis-(N2O2)−], by electron transfer from the Cu+ ion to the cis dimer (NO)2. This complex corresponds to the L → M charge transfer band in the region of 25600 cm−1. The subsequent destruction of the complex [Cu2+-cis-(N2O2)−] at temperatures of 150–300°C leads to the release of N2O and the formation of the complex [Cu2+O−], which further participates in the formation of the nitrite-nitrate complexes [Cu2+(NO2)−], [Cu2+(NO)(NO2)−], and [Cu2+(NO3)−] and NO decomposition products. 相似文献
9.
G. M. Kuz’micheva E. V. Savinkina L. I. Belogorokhova B. N. Mavrin V. R. Flid A. G. Yakovenko A. I. Belogorokhov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(6):1037-1040
The nanosized η-TiO2 polymorph was prepared by the hydrolysis of titanyl sulfate (TiO)SO4 · xH2SO4 · yH2O. η-TiO2 was studied by X-ray diffraction, X-ray photoelectron spectroscopy, IR spectroscopy, and Raman spectroscopy. Characteristic
X-ray data and distinguishing Raman spectrum features were found for η-TiO2,. The surface of η-TiO2 samples contained adsorbed OH− particles and water molecules or water molecules of crystal hydrates. The free specific surface area of samples with crystallite
sizes of L = 50 (4) and 60 (5) ? was S = 10.17 (9) and 15.6 (1) m2/g. The characteristics of samples with η-TiO2 were favorable for their use as photocatalysts and adsorbents. 相似文献
10.
Dartnell LR Page K Jorge-Villar SE Wright G Munshi T Scowen IJ Ward JM Edwards HG 《Analytical and bioanalytical chemistry》2012,403(1):131-144
Raman spectroscopy has proven to be a very effective approach for the detection of microorganisms colonising hostile environments
on Earth. The ExoMars rover, due for launch in 2018, will carry a Raman laser spectrometer to analyse samples of the martian
subsurface collected by the probe’s 2-m drill in a search for similar biosignatures. The martian surface is unprotected from
the flux of cosmic rays, an ionising radiation field that will degrade organic molecules and so diminish and distort the detectable
Raman signature of potential martian microbial life. This study employs Raman spectroscopy to analyse samples of two model
organisms, the cyanobacterium Synechocystis sp. PCC 6803 and the extremely radiation resistant polyextremophile Deinococcus radiodurans, that have been exposed to increasing doses of ionising radiation. The three most prominent peaks in the Raman spectra are
from cellular carotenoids: deinoxanthin in D. radiodurans and β-carotene in Synechocystis. The degradative effect of ionising radiation is clearly seen, with significant diminishment of carotenoid spectral peak
heights after 15 kGy and complete erasure of Raman biosignatures by 150 kGy of ionising radiation. The Raman signal of carotenoid
in D. radiodurans diminishes more rapidly than that of Synechocystis, believed to be due to deinoxanthin acting as a superior scavenger of radiolytically produced reactive oxygen species, and
so being destroyed more quickly than the less efficient antioxidant β-carotene. This study highlights the necessity for further
experimental work on the manner and rate of degradation of Raman biosignatures by ionising radiation, as this is of prime
importance for the successful detection of microbial life in the martian near subsurface. 相似文献
11.
Mohamad Mohsen Momeni Yousef Ghayeb Negin Moosavi 《Journal of Solid State Electrochemistry》2018,22(10):3137-3146
Cr-TiO2 nanotubes (Cr-TNTs) have been synthesized via facile one step anodization, followed by co-deposition by nickel-platinum via electroless deposition method. Field-emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD), and Raman spectroscopy have then been used to characterize the surface morphology and structure of the synthetic samples. The optical properties of the compounds have been investigated by ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy. Linear sweep voltammetry (LSV) and chronoamperometry were used to study the photoelectrochemical behavior of the obtained samples. The best electrochemical performer sample (t20) was recognized and evaluated in the presence of various aliphatic alcohols, as sacrificial agents, in photoelectrochemical cells (PEC) water splitting. In terms of sacrificial agent used, photocurrent density production was as follows: methanol > ethanol > glycerol > n-propanol > isopropanol > ethylene glycol. Also methanol concentration was optimized. Thus, both co-deposition of Cr-TNTs and addition of scavengers are promising methods to enhance the performance of catalysts for PEC. 相似文献
12.
Ying Jiang Marc Garland Keith J. Carpenter Parappuveetil S. Suresh Effendi Widjaja 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5697-5704
In this paper, the use of in situ Raman spectroscopy together with a novel multivariate data analysis method, band‐target entropy minimization (BTEM), is discussed to monitor the solution polymerization of methacrylamide in aqueous medium. Although FTIR spectroscopy is a more popular spectroscopic technique for polymer characterization and in situ polymerization monitoring, Raman spectroscopy is selected over FTIR in the current study. This is because water has very strong and broad infrared absorption bands and thus masks most of the other infrared signals contributed from monomer and polymer. On the contrary, water has very weak Raman scattering and thus it does not interfere the other Raman signals. The polymerization was initiated with potassium persulfate (KPS). A series of experiments were carried out varying initial monomer concentration, initial KPS concentration, and polymerization temperature. In situ Raman spectroscopy was used to monitor the polymerizing mixture and measure the compositions. The collected reaction spectra were subjected to BTEM to elucidate the pure component spectra, and then determine the conversion of monomer. The conversion data was then used to obtain kinetic parameters for the polymerization. The rate of consumption of monomers was found to follow the expression R = keff [I]0.55[M]1.41. The activation energy of the system was estimated at 121 kJ/mol. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5697–5704, 2007 相似文献
13.
The interactions of carotenoids (bixin, β-carotene and lycopene) with CCl3OO. in aqueous and i-propylalcohol solution saturated with air have been studied by pulse radiolysis. For bixin and β-carotene
reaction products from forming process, absorbing in the region of 650 nm, is observed with concomitant carotenoid bleaching
(bixin at 500 nm, β-carotene at 450 nm). Their rate constants from forming process are 1.78 ×108 and 7.8 ×107 mol-1 · L · s-1 respectively. However, in the case of lycopene, no such a forming process of reaction as bixin and β-carotene can be observed
although there is the bleaching reaction (rate constant 4 ×107 mol-1 · L · s-1). The results suggest that the carotenoid radical cation and an additional radical are produced in the case of bixin and
β-carotene, whereas lycopene undergoes electron transfer with CCl3OO., forming cation radical. 相似文献
14.
An improved method for the extraction of β-carotene from Blakeslea trispora is described. The fermentation broth was steamed at 121°C for 15 min, and the liquid was centrifuged at 5000g for 20 min.
β-Carotene was removed from the biomass by extraction with absolute ethanol at a ratio of 1:100 at 30°C for 2 h in a rotary
shaker incubator at 300 rpm. The carotenoid pigment was completely removed from the cells after three repeated extractions.
The removal of β-carotene from B. trispora was higher during the first stage (75%) whereas in the other stages it was very slow. 相似文献
15.
V. Ya. Kavun E. I. Voit S. L. Sinebryukhov A. B. Podgorbunskii O. V. Brovkina E. B. Merkulov V. K. Goncharuk 《Journal of Structural Chemistry》2011,52(6):1102-1105
19F NMR, IR, Raman and impedance spectroscopy are used to study the ionic mobility, structure, and conductivity of 45ZrF4-35BiF3-20CsF bismuth fluorozirconate glass. With the increase in temperature from 150 K to 500 K the fluorine-containing groups
pass from the rigid lattice to local movements (reorientations), and then to diffusion. According to the results of IR and
Raman spectroscopy, the lattice of this glass consists of ZrF8 polyhedra linked by their vertices into chains. The glass has high ionic conductivity: σ ≈ 1.8×10−4 S/cm in a temperature range of 480–485 K. 相似文献
16.
Controlled nanosized TiO2 particles of 4–10 nm were synthesized by a simple hydrolysis method followed by calcination at different temperatures. These
particles were investigated using X-ray diffraction (XRD), Photoacoustic/Fourier transform infrared (PA/FTIR) spectroscopy,
Raman spectroscopy and electron spin resonance (ESR) spectroscopy to understand their structural properties. X-ray diffraction
studies confirmed the anatase phase of the particles where as the PA/FTIR revealed the bands around 1,500 and 3,300 cm−1 due to –OH bands. ESR spectroscopic investigations carried out from 5 to 300 K indicated the presence of an ESR line at g = 2.00 emerging from radical species. It is significant to note that the intensity of the ESR line decreased as the particle
size increased. 相似文献
17.
Elizabeth A. Turner Harald Rösner Yining Huang John F. Corrigan 《Journal of Cluster Science》2007,18(3):764-771
Mercury-selenosulfide (HgSe
x
S
1-x
) nanoparticles have been synthesized using the single-source reagent Me3Si–SeS–SiMe3. The reagent distributes Se2− and S2− to the metal core as the reaction between Me3Si–SeS–SiMe3 and mercury acetate occurs via a redox pathway, ultimately giving rise to Se–S bond cleavage. Particles are characterized
by EDX, TEM and powder X-ray diffraction analysis in conjunction with UV–Visible absorption spectroscopy.
Dedicated to Prof. Dr. Dieter Fenske on the occasion of his 65th birthday. 相似文献
18.
Merlin C. E. Bandeira Joseph A. Crayston Norberto S. Gonçalves Lúcia K. Noda Andrew Glidle César V. Franco 《Journal of Solid State Electrochemistry》2007,11(2):231-239
The electropolymerization of trans-[RuCl2(vpy)4] (vpy=4-vinylpyridine) on Au or Pt electrodes was studied by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) technique, and Raman spectroscopy. Cyclic voltammetry of the monomer at a microelectrode shows the typical Ru(III/II) and Ru(IV/III) waves, together with the vinyl reduction waves at −1.5 and −2.45 V and adsorption wave at −0.8 V. Electrodeposition on EQCM technique performed under potential cycling between −0.9 and −2.0 V revealed that the polymerization proceeded well in advance of the vinyl reduction waves. At potentials more positive than −0.9 V, soluble oligomers were deposited irreversibly on the electrode during the oxidative sweep. The film also showed reversible mass changes due to the oxidation and accompanying ingress of charge-balancing anions and solvent into the film. In contrast, potentiostatic growth of the polymer at −1.6 V was slower because the oligomeric material was lost completely from the electrode. Unreacted vinyl groups were detected by in situ Raman spectroscopy for films grown at −0.7, −0.9, and −1.6 V but were absent when the polymerization was carried out at −2.9 V vs Ag/Ag+. 相似文献
19.
Summary A novel method is described for the determination of paracetamol (acetaminophen;N-acetyl-4-aminophenol) in urine. After reversed-phase HPLC separation, paracetamol is oxidized by H2O2 with horseradish peroxidase catalysis. Detection is performed fluorimetrically at an excitation wavelength of 329 nm and
an emission wavelength of 435 nm. Urine samples were spiked with paracetamol, diluted, and injected directly without further
pretreatment. Under these conditions, the limit of detection was 2×10−8 molL−1, and the limit of quantification was 7×10−8 molL−1. The method was validated by two different approaches based on HPLC with UV-Vis detection. 相似文献
20.
采用机械球磨法制备Y~(3+)修饰TiO_2光催化剂,利用紫外-可见漫反射光谱(UV-Vis DRS)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)、扫描电镜(SEM)等对其进行表征,在紫外光下,以亚甲基蓝(MB)为去除物来考察催化剂活性并优化球磨工艺。将最佳条件下制得的Y~(3+)/TiO_2光催化剂负载于不同半径的塑料浮球上,分别在紫外光和模拟太阳光照射下处理海水养虾废水,通过CODCr(chemical oxygen demand)及三维荧光观察有机物含量变化。结果表明,当Y~(3+)的物质的量分数为2%,球磨时间4 h,球料质量比4∶1,转速为500 r·min~(-1)时,MB光催化降解反应速率常数可达0.111 3 min~(-1),是纯TiO 2的4.2倍。由UV-Vis DRS、XPS、N_2吸附-脱附、XRD、SEM等表征结果显示,2%Y~(3+)/TiO_2样品的禁带宽度降低至3.05 eV,光吸收发生红移,并产生可见光响应,表面吸附氧含量明显增加,比表面积增大到104 m~2·g~(-1)。采用纯TiO_2及2%Y~(3+)/TiO_2为光催化剂处理养虾废水,在可见光和紫外光下CODCr的去除率分别为14.7%和18.8%、26.9%和37.5%。考察3种直径分别为1、2、3 cm负载Y~(3+)/TiO_2浮球的光催化效果,显示直径为2 cm浮球效果最佳,CODCr去除率可达38.5%。 相似文献