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1.
Abnormal cilia were demonstrated in the lining epithelial cells of three cases of intraspinal endodermal (bronchogenic) cyst. The changes comprised a wide spectrum of ultrastructural abnormalities, including (a). cilia with abnormal axonemal microtubules, (b). swollen cilia, (c). compound cilia with or without excessive ciliary matrix, (d). naked cilia without limiting membrane, and (e). intracytoplasmic cilia and aggregates of microtubules. Of these, compound cilia and swollen cilia were most common. Cilia with dynein arm deficiency were not observed. Ciliary abnormalities found in the present study were very similar to those described in the bronchial epithelium of various diseases. The present findings suggest that the lining epithelium of intraspinal endodermal cyst shares similar ciliogenesis and susceptibility to abnormal ciliary formation as that of the bronchial epithelium. 相似文献
2.
Powder X-ray diffraction (XRD) and Raman spectroscopic study of order-disorder-phase transition with increase in the content of Gd in Nd2−yGdyZr2O7 solid solution is being reported. It has been observed from Rietveld analysis that with increase in concentration of Gd in Nd2−yGdyZr2O7, the value of the x parameter of the 48f oxygen changes from 0.332(1) to 0.343(1) with a sudden change in the slope for y=1.8, which indicates that the structure is transforming from ordered pyrochlore to disordered pyrochlore. In addition to that a sudden and drastic change in the Raman spectra including changes in the position and width of several Raman modes beyond y?1.8 has also been observed which has been correlated with increasing disorder. Based on these studies, it is suggested that there is a discontinuous order-disorder transition from ‘perfect pyrochlore’ to ‘defect pyrochlore’ phase in Nd2−yGdyZr2O7 solid solution. 相似文献
3.
Yagi H Ramesha AR Kalena G Sayer JM Kumar S Jerina DM 《The Journal of organic chemistry》2002,67(19):6678-6689
We describe a novel and efficient synthesis (62-84% yields) of the eight possible, diastereomerically pure, cis and trans, R and S O(6)-allyl-protected N(2)-dGuo phosphoramidite building blocks derived through cis and trans opening of (+/-)-3alpha,4beta-dihydroxy-1beta,2beta-epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene [BcPh DE-1 (1)] and (+/-)-3alpha,4beta-dihydroxy-1alpha,2alpha-epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene [BcPh DE-2 (2)] by hexafluoropropan-2-ol (HFP)-mediated addition of O(6)-allyl-3',5'-di-O-(tert-butyldimethylsilyl)-2'-deoxyguanosine (3) at C-1 of the epoxides. Simply changing the relative amount of HFP used in the reaction mixture can achieve a wide ratio of cis/trans addition products. Thus, the observed cis/trans adduct ratio for the reaction of DE-1 (1) in the presence of 5 equiv of 3 varied from 17/83 to 91/9 over the range of 5-532 equiv of HFP. The corresponding ratios for DE-2 (2) varied from 2/98 to 61/39 under the same set of conditions. When 1 or 2 was fused with a 20-fold excess of 3 at 140 degrees C in the absence of solvent HFP, almost exclusive trans addition (>95%) was observed for the both DEs. Through the use of varying amounts of HFP in the reaction mixture as described above, each of the eight possible phosphoramidite oligonucleotide building blocks (DE-1/DE-2, cis/trans, R/S) of the BcPh DE N(2)-dGuo adducts can be prepared in an efficient fashion. To rationalize the varying cis-to-trans ratio, we propose that the addition of 3 to 1 or 2 in the absence of solvent or in the presence of small amounts of HFP proceeds primarily via an S(N)2 mechanism to produce mainly trans-opened adducts. In contrast, increasing amounts of HFP promote increased participation of an S(N)1 mechanism involving a relatively stable carbocation with two possible conformations. One of these conformations reacts with 3 to give mostly trans adduct, while the other conformation reacts with 3 to give mostly cis adduct. 相似文献
4.
Dhananjay B. Kendre 《Tetrahedron》2007,63(45):11000-11004
A convenient route was successfully developed for the synthesis of novel heterocycles such as pyrazolo[3,4-h][1,6]naphthyridine and dipyrazolo[3,4-b:3,4-d]pyridine (DPP) from pyrazolo[3,4-b]pyridine in good yield. The DPP derivatives synthesized were further studied for their fluorescence properties. 相似文献
5.
This study analyzes the stability of an initially sharp interface between two miscible fluids in a porous medium. Linear stability equations are first derived using the similarity variable of the basic state, and then transformed into a system of ordinary differential equations using a spectral expansion with and without quasi-steady-state approximation (QSSA). These transformed equations are solved using the eigenanalysis and initial value problem approach. The initial growth rate analysis shows that initially the system is unconditionally stable. The stability characteristics obtained under the present QSSA are quantitatively same as those obtained without the QSSA. To support these theoretical results, numerical simulations are conducted using the Fourier-spectral method. The results of theoretical linear stability analyses and the numerical simulations validate to each other. 相似文献
6.
Our earlier model of re-entrant liquid crystalline phases exhibited by highly polar compounds, in which the mutual orientation of near-neighbour molecules can change from an antiparallel to a parallel configuration, has been extended to include both nematic and smectic interactions. We show that, as the McMillan parameter alpha is decreased, the SmAd-SmA1 line goes over to the SmAd-N1Re line, finally becoming the NdRe-N1Re transition line, the latter ending in a critical point. This sequence is in agreement with the predictions of Prost's Landau model as well as with an experimental result. The phase sequence N-SmAd-NdRe-N1Re-SmA1 is obtained on cooling for a range of alphaA values. 相似文献
7.
Hemant P. Narkhede Uttam B. More Dipak S. Dalal Nilesh S. Pawar Dhananjay H. More 《合成通讯》2013,43(4):573-577
Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach. 相似文献
8.
Poojali P. Warekar Priyanka T. Patil Kirti T. Patil Dattatraya K. Jamale Govind B. Kolekar 《合成通讯》2016,46(24):2022-2030
An ecofriendly route has been investigated for the synthesis of 4-(4-nitro-phenyl)-2-phenyl-1,4-dihydro-benzo[4,5]imidazo[1,2-a]pyrimidine-3-carboxylic acid ethyl ester derivatives by one-pot, three-component condensation of ethyl benzoylacetate, aromatic aldehydes, and 2-amino benzimidazole using 260?mol% of citric acid as reaction mediator. Citric acid is an inexpensive, nontoxic, and green medium with smoothly activates the rate of reaction. The synthesized compounds were assessed for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37RV strain using the microplate alamar blue assay (MABA). The results indicate that among all the synthesized compound series, P-4 and P-9 compounds illustrate effective activity with a minimum inhibitory concentration of 25?µg/ml. 相似文献
9.
Physics of the Solid State - Polycrystalline samples of La0.67Sr0.33Mn0.65Fe0.35O3 (LSMFO) were synthesized using the standard ball mill method with different calcination temperatures ranging from... 相似文献
10.
Hiromu Kurosaki April A. Tucker Sarah E. Iden Shirley M. Sexton Benito D. Gonzalez Govind R. Rao 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1017-1022
Routine monitoring of urine is an effective way to detect occupational intake of radioactive material. Historically, determinations of uranium isotopic ratios have been performed by radiochemical separation followed by alpha spectrometry. With recent advancements in technology, inductively coupled plasma-mass spectrometry (ICP-MS) has become widely available for the determination of trace metals as well as radioactive nuclides with long half-lives, such as 238U in urine. Furthermore, ICP-MS measurements of 238U do not require radiochemical separation since the number of atoms in the sample is determined instead of the number of alpha particles emitted. However, this method does not provide good sensitivity for the determination of 235U due to its shorter half-life. An improved procedure using pre-concentration of uranium and determination by ICP-MS decreases the detection limit by a factor of ten or greater with only slight increase in total analysis time. The method also has the capability of accurately determining the isotopic ratio of the sample, which is very important in cases where enriched or depleted uranium is involved. 相似文献