substituent at the end of the hexyl chain and the nature of these substituents determines the differences in hydrogen bonding between the molecules. In each molecule, the m-methoxy substituents are virtually coplanar with the benzyl ring, while the p-methoxy substituent is almost perpendicular. The carbonyl O atomof the amide rotamer is trans related with the amidic H atom. In each structure, the benzamide N—H donor group and O acceptor atoms link the molecules into C(4) chains. In 1, a terminal –OH group links the molecules into a C(3) chain and the combined effect of the C(4) and C(3) chains is a ribbon made up of screw related R 2 2 (17) rings in which the O—H chain lies in the centre
The article presents arguments with a view to recognize that space is material and has possibly a fractal dimension in the range of from three to two. It is proposed that along to the unit of substance (atom) Some Unit of the field (vortex tubes) should be set. It is shown that the formation of the field structures being a kind “doubles” of atomic ones is possible. The existence of the three-zone electron structure is confirmed. It is indicated that this concept have already resulted in to the successful explanation of phenomena and to finding of their important parameters at different levels of the organization of matter.
A productive strategy in the crystal engineering is to build supramolecular structures from molecules that are programmed to engage in multiple interactions with the neighbours [1–3]. Hydrogen bonding system is the main key for organisation of mol- ecules containing complementary arrays of the hydrogen bonding sites [4–8]. The NAHN, NAHO, and OAHO hydrogen bonds are widely used for organisation of the components in the design of a large number and different types of supramolecular architec- tures as ribbons, rosettes, layers, tubes, rods, spheres and sheets [9–14]. Some supramolecular motifs ofhydrogen bonding patterns of symmetric and translational repetitive occurrence are important in the crystal and chemical engineering and technology . The usually weak CAHN and CAHO hydrogen bonds play also a sig- nificant role in the architectures, especially in the biological sys- tems [16–18]. A non-covalent association of proteins, formation of a phospholipid bilayer, interaction of a transcription factor with DNA, folding of a tRNA into its three-dimensional conformation are examples of processes that depend on the non-covalent interac- tions and organisations .
fur atomof the sulfonyl group (S1S2C1N1S3 fragment) in relation to the phenyl ring in the potassium salt preserve almost the same values as in the gas-phase which describes the most stable confor- mation of the ligand. The arrangement of the molecules in the crys- tal 2 (Fig. 2c) is mainly determined by the ionic interaction of the oppositely charged moieties, i.e. the 4-fluorophenylsulfonyldithio- carbimate(2-) ligand and the potassium cations surrounded by the water molecules. The water molecules interact with the potassium cations forming infinite 2D-layers parallel to the (0 0 1) plane at z = 0 and z = 1/2, while the 4-fluorophenylsulfonyldithiocarbi- mate(2-) ligands are alternatively oriented and located almost per- Table 3
UNDERSTANDING THE MOLECULAR STRUCTURE USING THE IONIZED HYDROGEN MOLECULE. In this paper a general view about the modern molecular structure theory is developed discussing the ionized hydrogen molecule. We introduce some necessary approximation methods for the electronic and nuclear spectra study adopting a systematic approach. In addition though, we have performed calculations in order to illustrate these methods.
It was found that the amount of negative charges of both carbon atoms of the double bond correlated with the reactivity of the reaction. Cycloaddition to α-humulene (5) occurred mainly to the C1–C2 double bond with the greatest amount of electric charges (–0.303), and in the minor isomer the dipole added to one of the other two double bonds C4–C5 with a larger sum of electric charges (–0.263). Similarly, in cycloaddition to trans caryophylene (10) in the major adduct 11 more reactive was an exocyclic double bond C8–C12 with total electric charges of –0.321, while the other double bond had a charge of –0.273. The same trend was observed in case of 5-vinyl-2-norbornene (21), where higher electron densities were found in the C2–C3 bond (–0.349/–0.342, exo/endo isomers), than in the C8–C9 bond(–0.264/−0.256, exo/endo isomers). It correlated with a higher reactivity of the C2–C3 bond affording 41% of mono-adducts 22 and 23 to this bond, and 38% of bis- adducts 24-27 to C2–C3 and C8–C9 bonds.
As it was mentioned, microaneurysms hyperpermeability is not associated with their size, however larger leaking microaneurysms had a greater chance of presenting with cysts. We can therefore conclude that, if microaneurysms' size does not contribute to fluid overproduction (as evaluated by FA), other mechanical mechanisms might be involved. Larger aneurysms can facilitate the formation of cysts by: 1) disturbing retinal tissue architecture/compliance and/or 2) by interfering with mechanisms of fluid clearance. First of all, microaneurysms of larger diameters may disrupt the integrity of natural barriers against fluid movement - such as the synaptic portion of outer plexiform layer (OPL) 7 and cause fluid accumulation. Secondly, they can potentially affect the functioning of nearby glial cells, particularly Muller cells, which are believed to play a central role in the interstitial flow of fluid by a K+ dependent mechanism. 34 Finally, microaneurysms represent regions of anormal/turbulent flow 19 and larger microaneurysms may diminish flow substantially within the deep retinal plexus, restricting normal fluid transportation and leading to cystoid edema. 34 However, despite the putative role of microaneurysms size in the formation of cysts, it is possible that cysts themselves may contribute to the microaneurysms expansion due to the presence of weak points in their vessel wall. 18 It should be interesting to further address these hypothesis in future clinical / histopathological studies.
In conclusion, an efficient method for the specific synthesis of α,β-unsaturated imines without catalysis by metal complexes was developed. Aliphatic aldimines bearing alpha hydrogen are not stable in acidic medium, and the imine-enimine tautomerism is favored. The nucleophilic attack of the enamine tautomer on the correspond- ing imine furnished aminoimine intermediates with two different configurations (pro-E-enimine and pro-Z-enimine). BLYP/6-31G* calculations showed that the transition state for the pro-E-enimine had a lower energy than the transition state for the pro-Z-inimine, but the intermediate pro-Z-enimine had a lower energy than the pro-E-enimine. Considering that the Z-enimine had a lower energy than the E-enimine while the latter was the principal product, the self-condensation of N-propylbutanimine must be kinetically con- trolled. An increase in temperature produced a higher proportion of the Z-isomer.
Ligand binding to the enzyme is generally driven by the difference in free energies of bound and unbound states. Consequently, the ionic equilibrium of the free ligand in solution influences the free energy of binding. The evident contribution of the ionic form of an inhibitor in aqueous medium at neutral pH (Figure 5B, see also QSAR approach in Figure 2) shows that the anionic ligand becomes neutral upon binding to CK2a. This is further supported by analysis of the lengths of nitrogen-nitrogen bonds in the triazole ringof TBBt in complex with CK2a (pdb1j91) , which are definitely not equal (1.242 and 1.419 A ˚ ). This, in turn, confirms the pattern of double and single N-N bonds characteristic for the neutral benzotriazole with a proton attached to either N(1) or N(3), in accordance with solution NMR data [21,22]. In this view, the pK a for proton dissociation in aqueous medium becomes a major
gular momentum quantum number. The suggestion of substituting the STOs by GTOs functions in the basis set expansion comes from the Gaussian product rule. This rule states that the product of two Gaussian, each located at different centres, may be writ- ten as a single Gaussian function centred at a point on the line segment that joins the two centres . This important property of Gaussian functions simplify significantly the calculations since the complicated bi-electronic integrals on three or four different atomic centres are reduced to integrals over two different centres. Despite this enormous advan- tage, from the analytical point of view, GTOs have two important handicaps that have a marked influence on the results. First, a Gaussian function does not have the desired cusp when r = 0 and second, it shows a more abrupt decay at large distances by comparison with a Slater function. To minimize the incorrect behaviour of the GTOs orbitals and to achieve results comparable, in terms of accuracy, to those obtained with the STOs functions, Contracted Gaussian-type Orbitals (CGTOs) [25, 26] were developed. In this approach a normalized linear combination of a few GTO’s, G α centred on the same atom
hour Holter recordings. Each record contains information of around 100,000 heartbeats. The first problem is based on the fact that fluctuation of the physiological signals possesses hidden information in the form of self-similarity, scale structure, monofractality and multifractality, through the application of these methods [8-13]. The fractal, multifractal and wavelet-based multifractal analysis of the fluctuations is useful not only for getting the comprehensive information for physiological signals of patients, but also provide a possibility for foresight, prognosis and prevention of the pathological statuses. The second problem is due to the large volume of research information is extremely important the correct determination the trend of the disease of the patients for relatively large period of time - several years, for instance. Such tests are performed periodically to compare the graphic characteristics of images from clinical studies undertaken as a result of treatment and give an idea of the patient's condition and treatment quality. Nonlinear analysis of cardiology data is a relatively new scientific approach to assess the dynamics of heart activity. The above described problems are solved by setting of the following interesting and important objectives:
only by means of sophisticated modeling tools, which are able to represent all known atmospheric physical and chemical processes and their interactions. During the pre- vious decade the development of such tools was substantially advanced reflecting the need for reliable climate and ozone layer forecasting on the one hand and the tremen- dous growth of computational capabilities on the other hand. Part of these advances
It is evident from metallographical examinations that the predominant part of intermetallics synthesised at 900 0 C for 30 minutes was synthesised in the region passing from a liquid state to a solid state. The temperature of 900 0 C promotes mass transfer of the alloying elements across the interface, which is responsible for the increase in volume fraction of the reaction products. Diffusion of chemical elements becomes easier, i.e. after 30 minutes of treating Ti can migrate through Cu to Fe, hence, copper layer cannot hinder the formation of brittle Ti-Fe-base intermetallics. With increasing annealing time up to 120 minutes at 900 0 C the structureof intermetallics was formed due to solid state transformations (Fig. 8).
With the aim of increasing the efficiency in the design process, accurate models for the evaluation of the delay introduced by each stage have been proposed in the literature [2, 3]. Although several models have been proposed, their accuracy is hindered by the use of the generally adopted quadratic law for the characterization of MOSFEs in saturation region of operation. During the last decade new models have been proposed for Ring VCOs using submicron technologies [4, 5]. Yet the necessity for integrating the VCO model into an optimization loop makes the EKV Mosfet model a best candidate for characterizing the devices behavior, since only one expression is valid for all regions of operation and from weak inversion till strong inversion.
The plant Prunus cerasoides D. Don (Rosaceae), was collected from Swat (Pakistan) in the year 2005, and was identified by Mr. Mehboob ur Rahman, Assistnat Professor, Department of Botany, Govt Jehanzeb Post Graduate Ccollege, Saidu Sharif, Swat, K.P.K., Pakistan. A voucher specimen (CP-14) has been deposited at the herbarium of the Department.
Data collection: CrystalClear (Rigaku/MSC 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).
Tree-ring datasets are used in a variety of circumstances, including archeology, climatology, forest ecology, and wood technology. These data are based on microdensity profiles and consist of a set of tree-ring descriptors, such as ring width or early/latewood density, measured for a set of individual trees. Because successive rings correspond to successive years, the resulting dataset is a ring variables 6 trees 6 time datacube. Multivariate statistical analyses, such as principal component analysis, have been widely used for extracting worthwhile information from ring datasets, but they typically address two- way matrices, such as ring variables 6 trees or ring variables 6 time. Here, we explore the potential of the partial triadic analysis (PTA), a multivariate method dedicated to the analysis of three-way datasets, to apprehend the space-time structureof tree-ring datasets. We analyzed a set of 11 tree-ring descriptors measured in 149 georeferenced individuals of European larch (Larix decidua Miller) during the period of 1967–2007. The processing of densitometry profiles led to a set ofring descriptors for each tree and for each year from 1967–2007. The resulting three-way data table was subjected to two distinct analyses in order to explore i) the temporal evolution of spatial structures and ii) the spatial structureof temporal dynamics. We report the presence of a spatial structure common to the different years, highlighting the inter-individual variability of the ring descriptors at the stand scale. We found a temporal trajectory common to the trees that could be separated into a high and low frequency signal, corresponding to inter-annual variations possibly related to defoliation events and a long-term trend possibly related to climate change. We conclude that PTA is a powerful tool to unravel and hierarchize the different sources of variation within tree-ring datasets.
The crystal structureof a synthetic AB-type carbonate apatite sample was analyzed by Rietveld refinement including a model with carbon atom not fixed in the B-site of the apatite structure. Only one constraint was applied to this model: the fractional occupancies of the atoms in the CO 3 ion plus PO 4 ion were equal 1.0 per phosphate site with six sites per unit cell. Rietveld refinement of the crystal structure with space group P6 3 /m results in cell parameters a = 9.3583(1) Å and c = 6.9226(5) Å; Z =1; R wp = 0.0824 and 9.5 wt. (%) of carbonate in this structure. The use of simple geometry formulas showed that the C atom is not located at the center of the equilateral triangle of oxygen O2, O3 and O3’, but to a distance 0.18 Å of this triangle. The results seem to indicate a new 3-D crystal structureof the carbonated apatite in PO 4 groups.
relative position of the dipeptide being the center of the cavity, during its geometry optimization it migrates to the edge of the IRMOF-phen-CH 3 and IRMOF-phen-Br in order to perform a hydrogen bond between the carboxylic oxygen and the hydrogen at the protonated histidyl ring. Thus the adsorption of the dipeptide changes remarkably with cavity environment.