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901.
Iraj Mohammadpoor-Baltork Majid Moghadam Shahram Tangestaninejad Valiollah Mirkhani Ahmad Reza Khosropour Arsalan Mirjafari 《Monatshefte für Chemie / Chemical Monthly》2010,14(1):1083-1088
Abstract
1-Methylimidazolium hydrogensulfate, [Hmim][HSO4], a Br?nsted acidic room temperature ionic liquid, is used as a catalyst and reaction medium for facile and eco-friendly deprotection of methoxymethyl (MOM) and ethoxymethyl (EOM) ethers to their corresponding alcohols under thermal conditions (Δ) and microwave irradiation (MW). Furthermore, one-pot interconversion to the respective acetates and trimethylsilyl (TMS) ethers was also achieved. 相似文献902.
Mid-infrared spectroscopy for detection of Huanglongbing (greening) in citrus leaves 总被引:2,自引:0,他引:2
In recent years, Huanglongbing (HLB) also known as citrus greening has greatly affected citrus orchards in Florida. This disease has caused significant economic and production losses costing about $750/acre for HLB management. Early and accurate detection of HLB is a critical management step to control the spread of this disease. This work focuses on the application of mid-infrared spectroscopy for the detection of HLB in citrus leaves. Leaf samples of healthy, nutrient-deficient, and HLB-infected trees were processed in two ways (process-1 and process-2) and analyzed using a rugged, portable mid-infrared spectrometer. Spectral absorbance data from the range of 5.15-10.72 μm (1942-933 cm−1) were preprocessed (baseline correction, negative offset correction, and removal of water absorbance band) and used for data analysis. The first and second derivatives were calculated using the Savitzky-Golay method. The preprocessed raw dataset, first derivatives dataset, and second derivatives dataset were first analyzed by principal component analysis. Then, the selected principal component scores were classified using two classification algorithms, quadratic discriminant analysis (QDA) and k-nearest neighbor (kNN). When the spectral data from leaf samples processed using process-1 were used for data analysis, the kNN-based algorithm yielded higher classification accuracies (especially nutrient-deficient leaf class) than that of the other spectral data (process-2). The performance of the kNN-based algorithm (higher than 95%) was better than the QDA-based algorithm. Moreover, among different types of datasets, preprocessed raw dataset resulted in higher classification accuracies than first and second derivatives datasets. The spectral peak in the region of 9.0-10.5 μm (952-1112 cm−1) was found to be distinctly different between the healthy and HLB-infected leaf samples. This carbohydrate peak could be attributed to the starch accumulation in the HLB-infected citrus leaves. Thus, this study demonstrates the applicability of mid-infrared spectroscopy for HLB detection in citrus. 相似文献
903.
904.
Arash Daghighi Kiumars Ghowsi Mohammad Reza Nilforoushan 《Journal of solution chemistry》2010,39(7):959-966
A new automated technique was developed for online monitoring of the conductance of a conductive type of cell. Shining metal
electrodes were used for the conductometry measurements and the frequency of the input signal was swept from a few hertz to
1 MHz. A theoretical model was developed based on the voltage dividing technique. The model was in good agreement with the
experimental results. Conductances of simple electrolytes such as HCl and micellar solutions were compared. Solutions of HCl
with concentrations as low as 45 μmol⋅L−1 were investigated. Critical micellar concentrations of two types of micelles, SDS and CPC, were also measured. It was shown
that this voltage divider circuit can be used for automated online conductometric titrations. 相似文献
905.
Hossein Amani Mohammad Reza Mehrnia Mohammad Hossein Sarrafzadeh Manouchehr Haghighi Mohammad Reza Soudi 《Applied biochemistry and biotechnology》2010,162(2):510-523
There is a lack of fundamental knowledge about the scale up of biosurfactant production. In order to develop suitable technology
of commercialization, carrying out tests in shake flasks and bioreactors was essential. A reactor with integrated foam collector
was designed for biosurfactant production using Bacillus subtilis isolated from agricultural soil. The yield of biosurfactant on biomass (Y
p/x), biosurfactant on sucrose (Y
p/s), and the volumetric production rate (Y) for shake flask were obtained about 0.45 g g−1, 0.18 g g−1, and 0.03 g l−1 h−1, respectively. The best condition for bioreactor was 300 rpm and 1.5 vvm, giving Y
x/s, Y
p/x, Y
p/s, and Y of 0.42 g g−1, 0.595 g g−1, 0.25 g g−1, and 0.057 g l−1 h−1, respectively. The biosurfactant maximum production, 2.5 g l−1, was reached in 44 h of growth, which was 28% better than the shake flask. The obtained volumetric oxygen transfer coefficient
(K
L
a) values at optimum conditions in the shake flask and the bioreactor were found to be around 0.01 and 0.0117 s−1, respectively. Comparison of K
L
a values at optimum conditions shows that biosurfactant production scaling up from shake flask to bioreactor can be done with
K
L
a as scale up criterion very accurately. Nearly 8% of original oil in place was recovered using this biosurfactant after water
flooding in the sand pack. 相似文献
906.
Raúl Terrazas Reza Carlos A. Martínez Pérez Claudia A. Rodríguez González Humberto Monreal Romero Perla E. García Casillas 《Central European Journal of Chemistry》2010,8(5):1041-1046
In this work, the synthesis of magnetite nanoparticles by two variant chemical coprecipitation methods that involve reflux
and aging conditions was investigated. The influence of the synthesis conditions on particle size, morphology, magnetic properties
and protein adsorption were studied. The synthesized magnetite nanoparticles showed a spherical shape with an average particle
size directly influenced by the synthesis technique. Particles of average size 27 nm and 200 nm were obtained. When the coprecipitation
method was used without reflux and aging, the smallest particles were obtained. Magnetite nanoparticles obtained from both
methods exhibited a superparamagnetic behavior and their saturation magnetization was particle size dependent. Values of 67
and 78 emu g−1 were obtained for the 27 nm and 200 nm magnetite particles, respectively. The nanoparticles were coated with silica, aminosilane,
and silica-aminosilane shell. The influence of the coating on protein absorption was studied using Bovine Serum Albumin (BSA)
protein.
相似文献
907.
Zohreh Derikvand Gholam Reza Talei Hossein Aghabozorg Marilyn M. Olmstead Azadeh Azadbakht Andya Nemati Jafar Attar Gharamaleki 《中国化学》2010,28(11):2167-2173
A mononuclear Cu(II) complex with mixed ligands, formulated as [Cu(hypydc)(dmp)]·H2O (hypydc=4‐hydroxypyridine‐2,6‐dicarboxylate, dmp=2,9‐dimethyl‐1,10‐phenanthroline), was synthesized and well characterized by single crystal X‐ray diffraction analysis, as well as spectroscopic (IR, UV‐Vis), and electrochemical methods. The Cu(II) atom exhibits a distorted square‐pyramidal geometry. Intermolecular O? H···O and C? H···O hydrogen bonds, π‐π stacking interactions and C? H···π interactions seem to be effective in the stabilization of the crystal structure. The complex was also evaluated for its antimicrobial activity using in vitro microdilution methods. Six standard bacteria and a strain of Candida albicans were used for the antimicrobial activities. There was a very strong activity against Candida albicans and significant activities against Enterococcus fecalis, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus, indicating important biological activities of the complex. 相似文献
908.
Park JJ Luo X Yi H Valentine TM Payne GF Bentley WE Ghodssi R Rubloff GW 《Lab on a chip》2006,6(10):1315-1321
We report facile in situ biomolecule assembly at readily addressable sites in microfluidic channels after complete fabrication and packaging of the microfluidic device. Aminopolysaccharide chitosan's pH responsive and chemically reactive properties allow electric signal-guided biomolecule assembly onto conductive inorganic surfaces from the aqueous environment, preserving the activity of the biomolecules. A transparent and nonpermanently packaged device allows consistently leak-free sealing, simple in situ and ex situ examination of the assembly procedures, fluidic input/outputs for transport of aqueous solutions, and electrical ports to guide the assembly onto the patterned gold electrode sites within the channel. Both in situ fluorescence and ex situ profilometer results confirm chitosan-mediated in situ biomolecule assembly, demonstrating a simple approach to direct the assembly of biological components into a completely fabricated device. We believe that this strategy holds significant potential as a simple and generic biomolecule assembly approach for future applications in complex biomolecular or biosensing analyses as well as in sophisticated microfluidic networks as anticipated for future lab-on-a-chip devices. 相似文献
909.
910.
M. Reza Emamy-K. 《Journal of Geometry》1999,65(1-2):91-100
Geometric methods of convex polytopes are applied to demonstrate a new connection between convexity and threshold logic. A cut-complex is a cubical complex whose vertices are strictly separable from rest of the vertices of then-cube by a hyperplane ofR
n
. Cutcomplexes are geometric presentations for threshold Boolean functions and thus are related to threshold logic. For an old classical theorem of threshold logic a shorter but geometric proof is given. The dimension of the cube hull of a cut-complex is shown to be the same as the maximum degree of the vertices in the complex. A consequence of the latter result indicates that any two isomorphic cut-complexes are isometric.This research was partially supported by FIPI-University of Puerto Rico, by Inter American University of Puerto Rico at Bayamon and by IPM, Tehran, Iran. 相似文献