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121.
Dr. Saul F. Teloxa Miguel Mellado-Hidalgo Dr. Stuart C. D. Kennington Prof. Pedro Romea Prof. Fèlix Urpí Prof. Gabriel Aullón Dr. Mercè Font-Bardia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200671
A direct and asymmetric triisopropylsilyltrifluoromethanesulfonate (TIPSOTf) mediated aldol reaction of N-azidoacetyl-1,3-thiazolidine-2-thione with aromatic aldehydes catalyzed by a chiral nickel(II)-Tol-BINAP complex has been developed (BINAP=2,2’-bis(diphenylphosphino)-1,1’-binaphthyl). The catalytic protocol gives the corresponding anti α-azido-β-silyloxy adducts with outstanding stereocontrol and in high yields. Theoretical calculations account for the stereochemical outcome of the reaction and lay the foundations for a mechanistic model. In turn, the easy removal of the thiazolidinethione yields a wide array of enantiomerically pure derivatives in a straightforward and efficient manner. Such a noteworthy character of the heterocyclic scaffold together with the appropriate manipulation of the azido group open a new route to the synthesis of di- and tripeptide blocks containing a β-aryl-β-hydroxy-α-amino acid. 相似文献
122.
123.
Jung YJ Hong BJ Zhang W Tendler SJ Williams PM Allen S Park JW 《Journal of the American Chemical Society》2007,129(30):9349-9355
Single-molecule force measurement methods have attracted increasing interest over recent years for the development of novel approaches for biomolecular screening. However, many of these developments are currently hindered by the available biomolecule surface attachment methods, in that it is still not trivial to create surfaces and devices with highly defined surface functionality and/or uniformity. Here we offer a new approach to address such issues based on the formation of dendron arrays. Through the measurement of forces between dendron surfaces functionalized with complementary DNA oligonucleotides, we observed several unique properties of the surfaces modified via this approach. The capability to record attractive or "jump-in" forces associated with molecular binding events is one of them. Additionally, these events occur in greater than 80% of measurements, and the forces are dependent on the number of complementary DNA bases of the associating strands while being insensitive to the measurement rate. Combined with a narrow distribution of both attractive forces and unbinding forces we suggest such functionalized surfaces offer a significant advance for fast and accurate force-based studies of oligonucleotide hybridization. 相似文献
124.
125.
Saul T. Epstein 《Theoretical chemistry accounts》1982,61(3):303-305
A formula, which includes the effects of finite nuclear masses, is derived for the force on a nucleus in a (possibly molecular) ion in a spatially uniform (possibly time dependent) electric field. 相似文献
126.
Saul L 《Physical review. B, Condensed matter》1992,46(21):13847-13851
127.
Photodynamic Treatment of Red Blood Cell Concentrates For Virus Inactivation Enhances Red Blood Cell Aggregation: Protection with Antioxidants 总被引:2,自引:0,他引:2
Ehud Ben-Hur Gregory Barshtein Shuqi Chen Saul Yedgar 《Photochemistry and photobiology》1997,66(4):509-512
Abstract— Photodynamic treatment (PDT) using phthalocyanines and red light appears to be a promising procedure for decontamination of red blood cell (RBC) concentrates for transfusion. A possible complication of this treatment may be induced aggregation of RBC. The production of RBC aggregates was measured with a novel computerized cell flow properties analyzer (CFA). The PDT of RBC concentrates with sulfonated aluminum phthalocy-anine (AIPcS4) and the silicon phthalocyanine Pc 4 under virucidal conditions markedly enhanced RBC aggregation and higher shear stress was required to disperse these aggregates. The clusters of cells were huge and abnormally shaped, unlike the rouleaux formed by untreated RBC. This aggregation was prevented when a mixture of antioxidants was included during PDT. Addition of the antioxidants after PDT reduced aggregation only partially. It is concluded that inclusion of antioxidants during PDT of RBC concentrates prior to transfusion may reduce or eliminate the hemodynamic risk that the virucidal treatment may present to the recipient. 相似文献
128.
The title compounds are stable in aqueous solution above pH 7, and can be isolated following N-acylation. 相似文献
129.
Woiciechowski AL Soccol CR Rocha SN Pandey A 《Applied biochemistry and biotechnology》2004,118(1-3):305-312
Cassava bagasse was hydrolyzed using HCl and the hydrolysate was used for the production of xanthan gum using a bacterial
culture of Xanthomonas campestris. Cassava bagasse hydrolysate with an initial concentration of approx 20 g of glucose/L proved to be the best substrate concentration
for xanthan gum production. Among the organic and inorganic nitrogen sources tested to supplement the medium—urea, yeast extract,
peptone, potassium nitrate, and ammonium sulfate—potassium nitrate was most suitable. Ammonium sulfate was the least effective
for xanthan gum production, and it affected sugar utilization by the bacterial culture. In media with an initial sugar concentration
of 48.6 and 40.4 g/L, at the end of fermentation about 30 g/L of sugars was unused. Maximum xanthan gum (about 14 g/L) was
produced when fermentation was carried out with a medium containing 19.8 g/L of initial reducing sugars supplemented with
potassium nitrate and fermented for 72 h, and it remained almost the same until the end of fermentation (i.e., 96 h). 相似文献
130.
Evaluation of an automated clean-up system for the isotope-dilution high-resolution mass spectrometric analysis of PCB, PCDD, and PCDF in food 总被引:2,自引:0,他引:2
E Eljarrat J Sauló A Monjonell J Caixach J Rivera 《Fresenius' Journal of Analytical Chemistry》2001,371(7):983-988
An automated clean-up system was evaluated for the simultaneous analysis of polychiorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), and biphenyls (PCB) in different foods. In addition to the seventeen 2,3,7,8-substituted PCDDIPCDF and four non-ortho PCB, by use of the clean-up system studied, it was possible to collect the eight mono-ortho and two di-ortho PCB and the seven indicator PCB in two separate fractions during the same clean-up run. The study was first performed using standard mixtures containing PCDD, PCDF and PCB, and a certified reference material. The recoveries of the 13C-labeled compounds ranged from 51 to 90%, indicating that the PCDD, PCDF, and PCB clean-up worked satisfactorily. Next, the automated system for PCDD, PCDF, and PCB analysis was evaluated for foods such as milk, egg, meat (beef, chicken, and pork), mussel, and olive oil. The recoveries of the 13C-labeled compounds ranged from 40 to 120% for PCB and from 57 to 113% for PCDD/ PCDF, meeting the requirements of well accepted methods. Thus, the automated clean-up system studied is a suitable alternative to conventional clean-up methods. 相似文献