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21.
The effect of injection on the flow of Oldroyd fluid in the inlet region of a channel has been investigated using the moment and energy integrals, taking into account the loss of energy due to viscous dissipation in the boundary layer. Analytical expression for boundary layer development has been presented. 相似文献
22.
Gary Chartrand Lisa Hansen Reza Rashidi Naveed Sherwani 《Czechoslovak Mathematical Journal》2000,50(1):35-46
A graph G is stratified if its vertex set is partitioned into classes, called strata. If there are k strata, then G is k-stratified. These graphs were introduced to study problems in VLSI design. The strata in a stratified graph are also referred to as color classes. For a color X in a stratified graph G, the X-eccentricity e
X(v) of a vertex v of G is the distance between v and an X-colored vertex furthest from v. The minimum X-eccentricity among the vertices of G is the X-radius radX
G of G and the maximum X-eccentricity is the X-diameter diamX
G. It is shown that for every three positive integers a, b and k with ab, there exist a k-stratified graph G with radX
G = a and diamX
G = b. The number s
X denotes the minimum X-eccetricity among the X-colored vertices of G. It is shown that for every integer t with radX
G t diamX
G, there exist at least one vertex v with e
X(v) = t; while if radX
G t s
X, then there are at least two such vertices. The X-center C
X(G) is the subgraph induced by those vertices v with e
X(v) = radX
G and the X-periphery P
X (G) is the subgraph induced by those vertices v with e
X(G) = diamX
G. It is shown that for k-stratified graphs H
1, H
2,..., H
k with colors X
1, X
2,..., X
k and a positive integer n, there exists a k-stratified graph G such that C
X
i(G) H
i (1 ; i
; k1) and
for i j. Those k-stratified graphs that are peripheries of k-stratified graphs are characterized. Other distance-related topics in stratified graphs are also discussed. 相似文献
23.
Sadiq‐ur‐Rehman Bilal Ahmad Khan Muhammad Aziz Chaudhary Khawaja Ansar Yasin Saqib Ali 《Heteroatom Chemistry》2015,26(6):417-425
Di‐ and triorganotin(IV) carboxylates, RnSn(OCOC(R2)=CHR1)4–n (n = 2 and 3; R = Me, Et, n‐Bu, Ph; R1 = 3‐CH3O‐4‐OHC6H3, R2 = C6H5) were prepared by reacting the corresponding organotin(IV) chloride with the silver salt of the (E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐phenylpropenoic acid. The title compounds were investigated and characterized by elemental analysis, infrared (FT‐IR), multinuclear (1H, 13C, 119Sn) NMR, and mass spectrometry, and possible structures were proposed. The complexes and ligand acid ( HL ) have been evaluated in vitro against various bacteria and fungi. The results noticed during the biocidal activity screenings proved their in vitro biological potential. They were also tested for cytotoxicity. 相似文献
24.
Tapentadol, a centrally acting analgesic was subjected to hydrolysis (acidic, alkaline, and neutral), oxidation, photolysis, humidity, and thermal stress conditions as per International Conference on Harmonization prescribed guidelines. Tapentadol was found susceptible to oxidative stress that produced two major degradation products DP-I and DP-II. However, it was stable to hydrolysis, photolysis, and thermal stress conditions. A simple, sensitive, and accurate high-performance liquid chromatography stability-indicating assay method (liquid chromatography–mass spectrometer compatible) was developed and validated for identification and characterization of stressed degradation products of Tapentadol. The chromatographic separation of the drug and its degradation products were achieved on Inertsil ODS, C18 (250 × 4.6 mm, i.d., 5 µm) column using a 12.5 mM aqueous ammonium acetate buffer (with 0.2% triethyl amine and final pH of buffer was adjusted to 3.60 with glacial acetic acid): acetonitrile (75:25, v/v) as a mobile phase. The degradation products were characterized by liquid chromatography mass spectrometry and subsequently its fragmentation pathway as well as plausible mechanism for generation of degradation products was also proposed. The stability indicating high-performance liquid chromatographic method was validated with respect to linearity, precision, and accuracy. 相似文献
25.
26.
Acid Catalyzed Efficient Syntheses of Aryl‐5H‐dibenzo[b,i]xanthene‐5,7,12,14‐(13H)‐tetraones and 3,3‐(Arylmethylene)bis(2‐hydroxynaphthalene‐1,4‐diones) and In Vitro Evaluation of their Antioxidant Activity 下载免费PDF全文
Jitender M. Khurana Anshika Lumb Ankita Chaudhary Bhaskara Nand 《Journal of heterocyclic chemistry》2014,51(6):1747-1751
A simple and efficient synthesis of aryl‐5H‐dibenzo[b,i]xanthene‐5,7,12,14‐(13H)‐tetraones and 3,3‐(arylmethylene)bis(2‐hydroxynaphthalene‐1,4‐diones) by the condensation of aromatic aldehydes and 2‐hydroxy‐1,4‐naphthoquinone under extremely mild conditions using catalytic amount of H2SO4 or in the presence of acidic ionic liquid 1‐butyl‐3‐methylimidazolium hydrogen sulphate, which could be recycled, has been reported. The radical scavenging capacity of the synthesized compounds has been examined towards the stable free radical 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), and the compounds 2 were found to scavenge DPPH free radical efficiently. 相似文献
27.
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
28.
R.H. Chilkulwar S.D. Sharma N. Chaudhary S. Acharya Y.S. Mayya K.C. Mittal L.M. Gantayet 《Radiation measurements》2012,47(8):628-633
The high dose rate electron beams are increasingly being used for radiation processing of various products worldwide. A comprehensive dosimetric evaluation of an in-house developed 10 MeV industrial electron beam irradiator was carried out in static as well as in dynamic mode of irradiations. Radiochromic B3 film and graphite calorimeter were used for dosimetric measurements. The dose rate from the electron beam was also calculated using the empirical relation prescribed in the ASTM report E2232-02. The measured electron beam profile indicates the dose rate variation within 8% in the irradiated product boxes. The most probable energy determined from the depth dose distribution in PMMA, Al and water was found in agreement with the intended energy of the electron beam. Measured dose rate using radiochromic film and graphite calorimeter were found in good agreement with each other and also found comparable with the theoretically estimated dose rates. Experimentally measured dose rates were considered for the trial irradiation of medical and industrial products. Dosimetric data obtained through this study confirms the suitability of the irradiator for routine radiation processing of various products. 相似文献
29.
Sudhakar Chaudhary V. V. K. Srinivas Kumar 《Numerical Functional Analysis & Optimization》2013,34(3):264-283
The objective of this article is to discuss the existence and the uniqueness of a weighted extended B-spline-(WEB-spline) based discrete solution for the Maxwell equations in low frequency limit. The domain is composed of insulating and conducting regions. This problem has saddle point structure where the electric field in insulating region is the Lagrange multiplier that forces curl-free constraint on the magnetic field. 相似文献
30.
Karsten Krohn Ishtiaq Ahmed Dietmar Gehle Mohammed Al Sahli 《Journal of carbohydrate chemistry》2013,32(2):64-77
Chiral building blocks for macrolides and related natural products are obtained from 1,6-anhydrosugars by conversion of the bicyclic acetals 2 or 12 into the open chain chiral 1,3-dithianes 6 and 13. Branched precursors can be obtained by opening of the ?erný epoxide 1 with the 1,3-dithiane anion to yield 7, followed by ring opening with 1,3-propanedithiol to the bis-1,3-dithiane 8. 相似文献