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51.
Saber Mohammadi Mohsen Masihi Mohammad Hossein Ghazanfari 《Transport in Porous Media》2012,91(3):973-998
Many heavy oil reservoirs contain discontinuous shales which act as barriers or baffles to flow. However, there is a lack
of fundamental understanding about how the shale geometrical characteristics affect the reservoir performance, especially
during polymer flooding of heavy oils. In this study, a series of polymer injection processes have been performed on five-spot
glass micromodels with different shale geometrical characteristics that are initially saturated with the heavy oil. The available
geological characteristics from one of the Iranian oilfields were considered for the construction of the flow patterns by
using a controlled-laser technology. Oil recoveries as a function of pore volumes of injected fluid were determined from analysis
of continuously recorded images during the experiments. We observed a clear bypassing of displacing fluid which results in
premature breakthrough of injected fluid due to the shale streaks. Moreover, the results showed a decrease of oil recovery
when shales’ orientation, length, spacing, distance of the shale from production well, and density of shales increased. In
contrast, an increase of shale discontinuity or distance of the shale streak from the injection well increased oil recovery.
The obtained experimental data have also been used for developing and validating a numerical model where good matching performance
has been observed between our experimental observations and simulation results. Finally, the role of connate water saturation
during polymer flooding in systems containing flow barriers has been illustrated using pore level visualizations. The microscopic
observations confirmed that besides the effect of shale streaks as heterogeneity in porous medium, when connate water is present,
the trapped water demonstrates another source of disturbance and causes additional perturbations to the displacement interface
leading to more irregular fingering patterns especially behind the shale streaks and also causes a reduction of ultimate oil
recovery. This study reveals the application of glass micromodel experiments for studying the effects of barriers on oil recovery
and flow patterns during EOR processes and also may provide a set of benchmark data for recovery of oil by immiscible polymer
flood around discontinuous shales. 相似文献
52.
The new experimental results on the effective quantum numbers and term energies of the highly excited odd-parity 4s4d 3D1,2,3 →4snf 3F2,3,4 Rydberg transitions of zinc have been presented. The experiment was performed using the three dye lasers simultaneously pumped by the second harmonic (532?nm) of the Q-switched Nd:YAG laser. The new observation includes the 4snf 3F3 (12?≤n?≤?50) series excited from the 4s4d 3D2 intermediate level. In addition, the 4snf 3F2 (12?≤n?≤?28) and 4snf3F4 (12?≤n?≤?33) series are observed from the thermally populated 4s4d 3D1,3 fine structure components. The ionization potential of zinc has been determined from the unperturbed 4snf 3F3 series as 75769.31?±?0.15?cm?1, which is in excellent agreement with the previously reported value. 相似文献
53.
54.
Najeeb Ur Rehman Hidayat Hussain Samia Ahmed Al‐Riyami René Csuk Mohammed Khiat Ghulam Abbas Ahmed Al‐Rawahi Ivan R. Green Ishtiaq Ahmed Ahmed Al‐Harrasi 《Helvetica chimica acta》2016,99(8):632-635
One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (1H‐ and 13C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC50 = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays. 相似文献
55.
Xiaohua Wang Jie Wang Ghulam Mustafa Kamal Bin Jiang Peng Sun Xu Zhang Maili Liu 《中国化学》2016,34(11):1183-1193
A holistic and comparative quality assessment of vinegars from different countries is needed with international trade of vinegar become frequent. In this study, compounds characterization and comparison of commercial‐grade Chinese cereal and European grape vinegars were performed using 1H NMR spectroscopy coupled with principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS‐DA). The results showed that Balsamic vinegars of Modena were clearly discriminated by higher amount of fructose and glucose, while Chinese aromatic vinegar and aged vinegars were characterized by higher amount of amino acids, volatile compounds, succinate and betaine. On the other hand, flavoring compounds in Chinese rice vinegar and European wine vinegars are less than the others. These characteristic components are associated with the special raw materials and producing process of each types of vinegar and endow them special flavor. The results obtained in this study provide a global insight into vinegar through a 1H NMR based compounds analysis that allows a holistic quality assessment and comparison of vinegars from different manufacture origins. 相似文献
56.
Parviz Aberoomand Azar Mohammad Saber Tehrani Sirwan Mohammadiazar Syed Waqif Husain 《Journal of separation science》2012,35(23):3354-3360
In the present work, the effect of substrate porosity for preparation of solid‐phase microextraction (SPME) fibers was investigated. The fibers were prepared by electrodeposition of sol‐gel coatings using negative potentials on porous Cu wire and compared with previous reported technique for preparation of SPME fibers using positive potentials on smooth gold wire. Porous substrate was prepared by electrodeposition of a thin layer of Cu on a Cu wire. The extraction capability of prepared fibers was evaluated through extraction of some aromatic hydrocarbons from the headspace of aqueous samples. The effect of substrate porosity and some operating parameters on extraction efficiency was optimized. The results showed that extraction efficiency of SPME fibers highly depends on porosity of the substrate. The LOD ranged from 0.005 to 0.010 ng/mL and repeatability at the 1 ng/mL was below 12%. Electrodeposited films were characterized for their surface morphology and thermal stability using SEM and thermogravimetric analysis, respectively. SEM analysis revealed formation of porous substrate and subsequently porous coating on the wire surface and thermogravimetric analysis showed high thermal stability of the prepared fiber. 相似文献
57.
Ishan Barman Narahara Chari Dingari Gajendra Pratap Singh Rajesh Kumar Stephen Lang Ghulam Nabi 《Analytical and bioanalytical chemistry》2012,404(10):3091-3099
In recent years, Raman spectroscopy has shown substantive promise in diagnosing bladder cancer, especially due to its exquisite molecular specificity. The ability to reduce false detection rates in comparison to existing diagnostic tools such as photodynamic diagnosis makes Raman spectroscopy particularly attractive as a complementary diagnostic tool for real-time guidance of transurethral resection of bladder tumor (TURBT). Nevertheless, the state-of-the-art high-volume Raman spectroscopic probes have not reached the expected levels of specificity thereby impeding their clinical translation. To address this issue, we propose the use of a confocal Raman probe for bladder cancer diagnosis that can boost the specificity of the diagnostic algorithm based on its suppression of the out-of-focus non-analyte-specific signals emanating from the neighboring normal tissue. In this article, we engineer and apply such a probe, having depth of field of approximately 280?μm, for Raman spectral acquisition from ex vivo normal and cancerous TURBT samples. Using this clinical dataset, a diagnostic algorithm based on principal component analysis and logistic regression is developed. We demonstrate that this approach results in comparable sensitivity but significantly higher specificity in relation to high-volume Raman spectral data. The application of only two principal components is sufficient for the discrimination of the samples underlining the robustness of the algorithm. Further, no discordance between replicate spectra is observed emphasizing the reproducible nature of the current diagnostic assessment. The high levels of sensitivity and specificity achieved in this proof-of-concept study opens substantive avenues for application of a confocal Raman probe during endoscopic procedures related to diagnosis and treatment of bladder cancer. Figure
Artistic depiction of the working principle of the confocal Raman spectroscopic sensor for urinary bladder cancer diagnosis 相似文献
58.
Schaeublin NM Braydich-Stolle LK Maurer EI Park K MacCuspie RI Afrooz AR Vaia RA Saleh NB Hussain SM 《Langmuir : the ACS journal of surfaces and colloids》2012,28(6):3248-3258
Gold nanomaterials (AuNMs) have distinctive electronic and optical properties, making them ideal candidates for biological, medical, and defense applications. Therefore, it is imperative to evaluate the potential biological impact of AuNMs before employing them in any application. This study investigates two AuNMs with different aspect ratios (AR) on mediation of biological responses in the human keratinocyte cell line (HaCaT) to model potential skin exposure to these AuNMs. The cellular responses were evaluated by cell viability, reactive oxygen species (ROS) generation, alteration in gene and protein expression, and inflammatory response. Gold nanospheres, nominally 20 nm in diameter and coated with mercaptopropane sulfonate (AuNS-MPS), formed agglomerates when dispersed in cell culture media, had a large fractal dimension (D(f) = 2.57 ± 0.4) (i.e., tightly bound and densely packed) and were found to be nontoxic even at the highest dose of 100 μg/mL. Highly uniform, 16.7 nm diameter, and 43.8 nm long polyethylene glycol-capped gold nanorods (AuNR-PEG) also formed agglomerates when dispersed into the cell culture media. However, the agglomerates had a smaller fractal dimension (D(f) = 1.28 ± 0.08) (i.e., loosely bound) and were found to be cytotoxic to the HaCaT cells, with a significant decrease in cell viability occurring at 25 μg/mL and higher. Moreover, AuNR-PEG caused significant ROS production and up-regulated several genes involved in cellular stress and toxicity. These results, combined with increased levels of inflammatory and apoptotic proteins, demonstrated that the AuNR-PEG induced apoptosis. Exposure to AuNS-MPS, however, did not show any of the detrimental effects observed from the AuNR-PEG. Therefore, we conclude that shape appears to play a key role in mediating the cellular response to AuNMs. 相似文献
59.
Sajid ZI Anwar F Shabir G Rasul G Alkharfy KM Gilani AH 《Molecules (Basel, Switzerland)》2012,17(4):3917-3932
This study appraises the antioxidant and antimicrobial attributes of various solvent extracts (absolute methanol, aqueous methanol, absolute ethanol, aqueous ethanol, absolute acetone, aqueous acetone, and deionized water) from bark, leaves and seeds of Pongamia pinnata (L.) Pierre. Maximum extraction yield of antioxidant components from bark (16.31%), leaves (11.42%) and seeds (21.51%) of P. pinnata was obtained using aqueous methanol (20:80). Of the extracts tested, the bark extract, obtained with aqueous methanol, exhibited greater levels of total phenolics [6.94 g GAE/100 g dry weight (DW)], total flavonoids (3.44 g CE/100 g DW), inhibition of linoleic acid peroxidation (69.23%) and DPPH radical scavenging activity (IC(50) value, 3.21 μg/mL), followed by leaves and seeds extracts. Bark extract tested against a set of bacterial and fungal strains also revealed the strongest antimicrobial activity with the largest inhibition zone and lowest minimum inhibitory concentration (MIC). HPLC analysis of aqueous methanol extracts from bark, leaves and seeds indicated the presence of protocatechuic, ellagic, ferulic, gallic, gentisic, 4-hydroxybenzoic and 4-hydroxycinnamic acids in bark (1.50-6.70 mg/100 g DW); sorbic, ferulic, gallic, salicylic and p-coumaric acids in leaves (1.18-4.71 mg/100 g DW); vanillic, gallic and tannic acids in seeds (0.52-0.65 mg/100 g DW) as the main phenolic acids. The present investigation concludes that the tested parts of P. pinnata, in particular the bark, have strong potential for the isolation of antioxidant and antimicrobial agents for functional food and pharmaceutical uses. 相似文献
60.
Claude Bardos Isabelle Catto Norbert Mauser Saber Trabelsi 《Archive for Rational Mechanics and Analysis》2010,198(1):273-330
In this paper, we formulate and analyze the multi-configuration time-dependent Hartree–Fock (MCTDHF) equations for molecular systems with pairwise interaction. This set of coupled nonlinear PDEs and ODEs is an approximation of the N-particle time-dependent Schrödinger equation based on (time-dependent) linear combinations of (time-dependent) Slater determinants. The “one-electron” wave-functions satisfy nonlinear Schrödinger-type equations coupled to a linear system of ordinary differential equations for the expansion coefficients. The invertibility of the one-body density matrix (full-rank hypothesis) plays a crucial rôle in the analysis. Under the full-rank assumption a fiber bundle structure emerges and produces unitary equivalence between different useful representations of the MCTDHF approximation. For a large class of interactions (including Coulomb potential), we establish existence and uniqueness of maximal solutions to the Cauchy problem in the energy space as long as the density matrix is not singular. A sufficient condition in terms of the energy of the initial data ensuring the global-in-time invertibility is provided (first result in this direction). Regularizing the density matrix violates energy conservation. However, global well-posedness for this system in L 2 is obtained with Strichartz estimates. Eventually, solutions to this regularized system are shown to converge to the original one on the time interval when the density matrix is invertible. 相似文献