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121.
Mathematics Support Centres are to be found in various formsin the majority of UK higher education institutions. They havebeen established in order to ease widespread and serious difficultiesthat a significant number of students have with mathematics,particularly at the school–university transition. Theyusually offer mathematics and/or statistics support to studentsacross the full range of disciplines studied. Anecdotal evidencesuggests that those students who make good use of such centresare not just those who struggle with mathematics. Many frequentusers are quite competent and simply want to do better. Thestudy reported here describes and analyses data from one cohortof engineering students. A novel aspect is the quantificationof the proportion of support centre visitors who fall into these,and other, categories. We conclude of the cohort in the study,mathematics support has improved the pass rate by 3%. Of thefailures, about half (4% of the sample total) could well havepassed had they attended the mathematics support centre regularly.Furthermore, the majority of those attending were not studentswho were in danger of failing. This has important implicationsnot only for the design of mathematics support provision, butalso for the performance of the high fliers. The methodologyoffers one way tackling the difficult task of evaluating theeffectiveness of mathematics support initiatives. 相似文献
122.
G. Thirupathi E. Yadaiah Goud Y. Hemasri MD. Suban Ali Y. Jayaprakash Rao 《Journal of the Iranian Chemical Society》2017,14(2):477-483
A facile, convenient, efficient and high-yielding synthesis of 3-aroylcoumarinoflavones has been developed by the condensation of easily synthesized 7-hydroxy-8-formylflavones and benzoyl acetonitriles in the presence of catalytic amount of l-proline in ethanol reflux. All the synthesized compounds were evaluated for their antioxidant activity. Some of the compounds showed very good activity compared to standard BHT. 相似文献
123.
Daniel A Paterson Jordan P Abberley William TA Harrison John MD Storey 《Liquid crystals》2017,44(1):127-146
ABSTRACTThe synthesis and characterisation of several members of the 1,ω-bis(4-cyanobiphenyl-4′-yl) alkane (CBnCB) and the 1-(4-cyanobiphenyl-4′-yloxy)-ω-(4-cyanobiphenyl-4′-yl) alkane (CBnOCB) homologous series are reported. The new odd members described CB5CB, CB13CB, CB4OCB, CB8OCB and CB10OCB all exhibit twist-bend nematic and nematic phases. The members of these series already reported in literature, CB7CB, CB9CB, CB11CB and CB6OCB, were also prepared in order to allow for a direct comparison of their transitional properties. The properties of these dimers are also compared to those of the corresponding members of the 1,ω-bis(4-cyanobiphenyl-4,-yloxy) alkanes (CBOnOCB). For any given total spacer length, for odd members of these series, the nematic–isotropic transition temperatures and associated entropy changes are greatest for the CBOnOCB dimer and lowest for the CBnCB dimer. These trends are understood in terms of molecular shape. For short spacer lengths, the twist-bend nematic–nematic transition temperature (TNTBN) is higher for the CBnOCB series than for the CBnCB series but this is reversed as the spacer length increases. Of the CBOnOCB dimers, a virtual value of TNTBN was estimated for CBO3OCB and TNTBN was measured for CBO5OCB. These values are considerably lower than those observed for the corresponding members of the CBnCB or CBnOCB series. The dependence of TNTBN on molecular structure is discussed not only in terms of the molecular curvature but also in the ability of the molecules to pack efficiently. As the temperature range of the preceding nematic phase increases, so the twist-bend nematic–nematic transition entropy change decreases and the transition approaches second order for the longer spacers. For comparative purposes, the transitional behaviour of the even-membered dimers CB6CB, CB5OCB and CBO4OCB is reported and differences accounted for in terms of molecular shape. 相似文献
124.
Dr. Wolfgang Jahnke Dr. Guido Bold Dr. Andreas L. Marzinzik Dr. Silvio Ofner Xavier Pellé Dr. Simona Cotesta Emmanuelle Bourgier Sylvie Lehmann Chrystelle Henry René Hemmig Dr. Frédéric Stauffer Dr. J. Constanze D. Hartwieg Dr. Jonathan R. Green Dr. Jean‐Michel Rondeau 《Angewandte Chemie (International ed. in English)》2015,54(48):14575-14579
Targeting drugs to their desired site of action can increase their safety and efficacy. Bisphosphonates are prototypical examples of drugs targeted to bone. However, bisphosphonate bone affinity is often considered too strong and cannot be significantly modulated without losing activity on the enzymatic target, farnesyl pyrophosphate synthase (FPPS). Furthermore, bisphosphonate bone affinity comes at the expense of very low and variable oral bioavailability. FPPS inhibitors were developed with a monophosphonate as a bone‐affinity tag that confers moderate affinity to bone, which can furthermore be tuned to the desired level, and the relationship between structure and bone affinity was evaluated by using an NMR‐based bone‐binding assay. The concept of targeting drugs to bone with moderate affinity, while retaining oral bioavailability, has broad application to a variety of other bone‐targeted drugs. 相似文献
125.
For ?1≤B<A≤1, let \(\mathcal {S}^{*}(A,B)\) denote the class of normalized analytic functions \(f(z)= z+{\sum }_{n=2}^{\infty }a_{n} z^{n}\) in |z|<1 which satisfy the subordination relation z f ′(z)/f(z)?(1 + A z)/(1 + B z) and Σ?(A,B) be the corresponding class of meromorphic functions in |z|>1. For \(f\in \mathcal {S}^{*}(A,B)\) and λ>0, we shall estimate the absolute value of the Taylor coefficients a n (?λ,f) of the analytic function (f(z)/z)?λ . Using this we shall determine the coefficient estimate for inverses of functions in the classes \(\mathcal {S}^{*}(A,B)\) and Σ?(A,B). 相似文献
126.
Docampo Palacios ML Fascio ML Fernández Villalobo A Pellón RF 《Magnetic resonance in chemistry : MRC》2009,47(2):174-178
(1)H and (13)C spectroscopic data for 5H-[1,3]thiazolo[2,3-b]quinazolin-5-one and 12H-[1,3]benzothiazolo[2,3-b]quinazolin-12-one derivatives were fully assigned by combination of one- and two-dimensional experiments (DEPT, HMBC and HMQC). Both heterocyclic systems show similar spectroscopic properties with some remarkable differences. 相似文献
127.
O. Díaz Rizo M. V. Manso Guevara E. Herrera Peraza I. Alvarez Pellón M. C. López Reyes D. López Aldana F. Garcia Yip 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):391-393
The experimental dependence of the α,f andT
n
parameters, in function of the water thickness, for different irradiation channels of Triga Mark III reactor, were analyzed.
An exponential law for the α(r) dependence was obtained in the neighborhood of the active zone of the reactor numerically modelated using theS
n
method for 69 neutrons groups, and this dependence is slower in light water reactors than in graphite reactors. 相似文献
128.
José P. Carvalho Aleksander Jaworski Michael J. Brady Andrew J. Pell 《Magnetic resonance in chemistry : MRC》2020,58(11):1055-1070
A new approach for processing satellite-transition magic-angle spinning (STMAS) and multiple-quantum magic-angle spinning (MQMAS) data, based on the two-dimensional one-pulse (TOP) method, which separates the second-rank quadrupolar anisotropy and paramagnetic shift interactions via a double shearing transformation, is described. This method is particularly relevant in paramagnetic systems, where substantial inhomogeneous broadening may broaden the lineshapes. Furthermore, it possesses an advantage over the conventional processing of MQMAS and STMAS spectra because it overcomes the limitation on the spectral width in the indirect dimension imposed by rotor synchronization of the sampling interval. This method was applied experimentally to the Al solid-state nuclear magnetic resonance of a series of yttrium aluminum garnets (YAGs) doped with different lanthanide ions, from which the quadrupolar parameters of paramagnetically shifted and bulk unshifted sites were extracted. These parameters were then compared with density functional theory calculations, which permitted a better understanding of the local structure of Ln substituent ions in the YAG lattice. 相似文献
129.
MD. Harun‐Or Rashid Myungeun Seo Sang Youl Kim Yeong‐Soon Gal Jong Myung Park Eun Young Kim Won‐Ki Lee Kwon Taek Lim 《Journal of polymer science. Part A, Polymer chemistry》2011,49(21):4680-4686
Regioregular poly(3‐hexylthiophene)‐b‐poly(1H,1H‐dihydro perfluorooctyl methacrylate) (P3HT‐b‐PFOMA) diblock copolymers were synthesized by atom transfer radical polymerization of fluorooctyl methacrylate using bromoester terminated poly(3‐hexylthiophene) macroinitiators in order to investigate their morphological properties. The P3HT macroinitiator was previously prepared by chemical modification of hydroxy terminated P3HT. The block copolymers were well characterized by 1H NMR spectroscopy and gel permeation chromatography. Transmission electron microscopy was used to investigate the nanostructured morphology of the diblock copolymers. The block copolymers are able to undergo microphase separation and self‐assemble into well‐defined and organized nanofibrillar‐like micellar morphology. The development of the morphology of P3HT‐b‐PFOMA block copolymers was investigated after annealing in solvent vapor and also in supercritical CO2. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
130.
The synthesis of 11H-pyrido[2,1-b]quinazolin-11-one (IV) and derivatives, by the condensation of o-chlorobenzoic acid and 2-aminopyridine in DMF is reported. 相似文献