999 resultados para 622.3


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The 1122 (n=2) member of the Tl(Ca,Ba)n+1CunO2n+3 series containing a single Tl-O layer is shown to be associated with a Tc of 90 K. This value of Tc is significantly lower than that of the 2122 phase (Tcnot, vert, similar110 K) with two Tl-O layers.

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Strips within commercial crops of Stylosanthes guyanensis in the Mareeba district of north Queensland were sprayed with diquat 4, 6 and 10 days before harvest and compared with unsprayed strips. Pre-harvest desiccation made combine harvesting easier, but did not increase harvest yield. Where seed formation and maturation was still possible, desiccation prevented this without substantially increasing the loss of seed to the ground; increased harvest efficiency was thus offset by a diminished quantity of standing seed. However, where there was little or no further potential for seed development, diquat had virtually no effect on the quantity of standing seed or harvest efficiency. It was concluded that the results warranted neither recommendation nor further evaluation of preharvest desiccation of S. guyanensis seed crops.

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Organic/inorganic hybrid gels have been developed in order to control the three-dimensional structure of photoactive nanofibers and metallic nanoparticles (NPs). These materials are prepared by simultaneous self-assembly of the 2,3-didecyloxyanthracene (DDOA) gelator and of thiol-capped gold nanoparticles (AuNPs). TEM and fluorescence measurements show that alkane-thiol capped AuNPs are homogeneously dispersed and tightly attached to the thermoreversible fibrillar network formed by the organogelator in n-butanol or n-decanol. Rheology and thermal stability measurements reveal moreover that the mechanical and thermal stabilities of the DDOA organogels are not significantly altered and that they remain strong, viscoelastic materials. The hybrid materials display a variable absorbance in the visible range because of the AuNPs, whereas the strong luminescence of the DDOA nanofibers is efficiently quenched by micromolar amounts of AuNPs. Besides, we obtained hybrid aerogels using supercritical CO2. These arc very low-density porous materials showing fibrillar networks oil which fluorinated gold NPs arc dispersed. These hybrid materials are of high interest because of their tunable optical properties and are under investigation for efficient light scattering.

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The temperature variation of the 3’Cl n.q.r. frequencies in 3,5- and 2,3- dichloroanisoles has been reported here. Both compounds show two lines each, and these have been assigned to the two chlorines in the same molecule with the help of the additive model for the substituent effect. The temperature dependence has been analysed in terms of Bayer-Kushida-Brown model.The torsional frequencies and their temperature dependence have been calculated numerically under a two-mode approximation. 0.n comparing the results in 3,5-dichloroanisole with those in 3,5-dichlorophenol it can be seen that they show similar behaviour owing to the absence of hydrogen bonding in both.

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3,3',5,5'-Tetrabromo-4,4'-dlaminodlphenyMhane has been synthedzed and Its spectral and thermal characterlstlcs have been examined.

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The role of the electronic kinetic energy and its Cartesian components is examined during the formation of the first excited 1�£ and the lowest 3�£ states of HeH+ employing wavefunctions of multi-configuration type with basis orbitals in elliptic coordinates. Results show that the bond formation in these states is preceded primarily by a charge transfer from H to He+ rather than by polarisation of the H-orbital by He+

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Infrared spectra of 1,3-dithiole-2-thione (DTT) and its four selenium analogues have been studied in the region 4000 to 20 cm�1. Assignment of all the fundamental frequencies was made by noting the band shifts on progressive selenation. Normal coordinate analysis procedures have been applied for both in-plane and out-of-plane vibrations to help the assignments. The Urey�Bradley force function supplemented with valence force constants for the out-of-plane vibrations was employed for coordinate calculations. A correlation of the infrared assignments of DTT with its different selenium analogues is accomplished. Further, the infrared assignments are compared with those of trithiocarbonate ion and its selenium analogues and other structurally related heterocyclic molecules.

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C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3' O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

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The technology scene in India is at one and the same time promising, frustrating and fascinating. Three broad areas in technology development can be distinguished. The first is relatively small scale; it is typified by the absorption of products of the industrial revolution into the repertoire of the Indian artisan and craftsman, examples being diesel engines from Kolhapur and centrifugal pumps from Coimbatore. The second class is essentially 'state technology', developed at public expense by national commissions: agriculture, atomic energy and space are examples. There is a vast third area in both private and public sector, covering products for the urban consumer and the state (e.g. r defence); this area has largely remained colonial. The factors affecting the three areas of technology are described and analysed from the point of view of an Indian scientistengineer; and it is concluded that the enormous potential of the country's human and mat.erial resources is not only unrealized, but even unrecognized as yet.

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Various reasons, such as ethical issues in maintaining blood resources, growing costs, and strict requirements for safe blood, have increased the pressure for efficient use of resources in blood banking. The competence of blood establishments can be characterized by their ability to predict the volume of blood collection to be able to provide cellular blood components in a timely manner as dictated by hospital demand. The stochastically varying clinical need for platelets (PLTs) sets a specific challenge for balancing supply with requests. Labour has been proven a primary cost-driver and should be managed efficiently. International comparisons of blood banking could recognize inefficiencies and allow reallocation of resources. Seventeen blood centres from 10 countries in continental Europe, Great Britain, and Scandinavia participated in this study. The centres were national institutes (5), parts of the local Red Cross organisation (5), or integrated into university hospitals (7). This study focused on the departments of blood component preparation of the centres. The data were obtained retrospectively by computerized questionnaires completed via Internet for the years 2000-2002. The data were used in four original articles (numbered I through IV) that form the basis of this thesis. Non-parametric data envelopment analysis (DEA, II-IV) was applied to evaluate and compare the relative efficiency of blood component preparation. Several models were created using different input and output combinations. The focus of comparisons was on the technical efficiency (II-III) and the labour efficiency (I, IV). An empirical cost model was tested to evaluate the cost efficiency (IV). Purchasing power parities (PPP, IV) were used to adjust the costs of the working hours and to make the costs comparable among countries. The total annual number of whole blood (WB) collections varied from 8,880 to 290,352 in the centres (I). Significant variation was also observed in the annual volume of produced red blood cells (RBCs) and PLTs. The annual number of PLTs produced by any method varied from 2,788 to 104,622 units. In 2002, 73% of all PLTs were produced by the buffy coat (BC) method, 23% by aphaeresis and 4% by the platelet-rich plasma (PRP) method. The annual discard rate of PLTs varied from 3.9% to 31%. The mean discard rate (13%) remained in the same range throughout the study period and demonstrated similar levels and variation in 2003-2004 according to a specific follow-up question (14%, range 3.8%-24%). The annual PLT discard rates were, to some extent, associated with production volumes. The mean RBC discard rate was 4.5% (range 0.2%-7.7%). Technical efficiency showed marked variation (median 60%, range 41%-100%) among the centres (II). Compared to the efficient departments, the inefficient departments used excess labour resources (and probably) production equipment to produce RBCs and PLTs. Technical efficiency tended to be higher when the (theoretical) proportion of lost WB collections (total RBC+PLT loss) from all collections was low (III). The labour efficiency varied remarkably, from 25% to 100% (median 47%) when working hours were the only input (IV). Using the estimated total costs as the input (cost efficiency) revealed an even greater variation (13%-100%) and overall lower efficiency level compared to labour only as the input. In cost efficiency only, the savings potential (observed inefficiency) was more than 50% in 10 departments, whereas labour and cost savings potentials were both more than 50% in six departments. The association between department size and efficiency (scale efficiency) could not be verified statistically in the small sample. In conclusion, international evaluation of the technical efficiency in component preparation departments revealed remarkable variation. A suboptimal combination of manpower and production output levels was the major cause of inefficiency, and the efficiency did not directly relate to production volume. Evaluation of the reasons for discarding components may offer a novel approach to study efficiency. DEA was proven applicable in analyses including various factors as inputs and outputs. This study suggests that analytical models can be developed to serve as indicators of technical efficiency and promote improvements in the management of limited resources. The work also demonstrates the importance of integrating efficiency analysis into international comparisons of blood banking.

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Regional variety trials (RVT) established in 1983 and again in 1997 identified superior varieties for the macadamia industry. From the 1983 trials, guidelines were developed to assist growers to select the most appropriate new varieties for their particular orchards and many of these superior varieties have been enthusiastically adopted by industry. This is also being done for varieties in the 1997 trials. Many of the best cultivars have already been adopted by growers on the basis of annual reports of yield and quality. Industry development over the next 10 to 20 years will be largely dependent on new, superior varieties selected in these RVT5, including new selections from the macadamia industry breeding program.

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C12HI6N206 is orthorhombic, P2x2121, with a = 19.890 (5), b = 12.789 (2), c = 5.236 (1) A, Z = 4, U = 1331.9/~ 3, F(000) = 600. Mo Ka (/~ = 0.123 mm -1) intensities for 940 unique reflections up to sin 0/2 = 0.538/k -1 were collected on a CAD-4 diffractometer. Final R = 0.034. The glycosidic torsion angle 2~CN is 3"4 °, significantly smaller than that (56.5 °) in 2',3'- -methoxymethyleneuridine (MMU). The ribose moiety has a C(3')-exo-C(4')-endo twist conformation, in contrast to the C(2')-endo conformation in MMU. However, the maximum amplitudes of pucker for the ribose and dioxolane rings are very nearly the same for the two structures. The conformation about C(4')-C(5') is gauche-gauche (~0oo = -68-4, Ooc = 51.3°).