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AIM Incremental haemodialysis (HD) regimen has recently gained attention. However, its efficacy and safety, compared with conventional thrice-weekly HD, are controversial and previous research results are not convincing. We sought to conduct a meta-analysis to evaluate the benefits and limitations of incremental HD regimen in patients with end-stage renal disease. METHODS We searched PubMed, Embase, and the Cochrane Central Register databases for controlled trials published until January 2017. Outcomes of interest included baseline patient characteristics, mortality risk, renal function, urine volume, laboratory values, and hospitalization rate. RESULTS Overall, 16 studies (n = 252 330), including 15 observational studies and 1 cross-sectional study, were included. Incremental HD reduced mortality risk, compared with conventional HD (risk ratio [RR], 0.797; 95% confidence interval [CI], 0.731-0.870; P < 0.001; I2 = 0%). Renal function (standardized mean difference [SMD] = 0.677, 95% CI: 0.035 to 1.318, P = 0.039; I2 = 92.7%) and urine volume (weighted mean difference [WMD] = 333.37, 95% CI: 86.81 to 579.93, P = 0.008; I2 = 92.7%) were also better preserved in patients on incremental HD. Other clinical outcomes, including serum levels of calcium, phosphate, albumin, haemoglobin, and hospitalization rate, were similar between groups. CONCLUSION An incremental therapeutic approach as a beginning haemodialysis regimen is associated with lower mortality and better preservation of greater residual renal function.

Using catastrophe theory and the concept of a mutation path, an algorithm is developed that leads to the direct correlation of the normal vibrational modes of two structurally related molecules. The mutation path is defined by weighted incremental changes in mass and geometry of the molecules in question, which are successively applied to mutate a molecule into a structurally related molecule and thus continuously converting their normal vibrational spectra from one into the other. Correlation diagrams are generated that accurately relate the normal vibrational modes to each other by utilizing mode-mode overlap criteria and resolving allowed and avoided crossings of vibrational eigenstates. The limitations of normal mode correlation, however, foster the correlation of local vibrational modes, which offer a novel vibrational measure of similarity. It will be shown how this will open new avenues for chemical studies. © 2017 Wiley Periodicals, Inc.

According to the first-principle calculations, the aromatic Al42− unit can sandwich the two transition metal (TM) atoms forming a stable all-metal binuclear compound [Al4TM2Al4]q- (q=-2,0,2; TM=Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta). The stability analysis shows that these all-metal binuclear compounds Al4TM2Al4 exist as stable complexes forming aluminum rings which can maintain their two-fold aromaticity of the molecule, which is either the σ or the π aromaticity. Moreover the interaction between Al4Sc2Al4 and hydrogen atom has been also studied using density functional theory (DFT). It has been found that one Al4Sc2Al4 molecule can adsorb 12 hydrogen atoms, whose hydrogen storage mass density is 3.77 wt%. Furthermore, the average binding energy which is in the range between 0.2-0.7 eV/H2, can be either adsorbed or desorbed reversibly under near standard conditions. We have also found that a multicenter bond is formed between the H atoms and the Al or Sc atoms during the process of hydrogen adsorption, which is characterized by specific vibration frequency. Therefore, in order to store hydrogen reversibly and effectively, we can select the specific mode in the infrared band which is able to induce the hydrogen desorption from that which is adsorbed by Al8Sc2.

The conformational landscape and ring-puckering properties of e-caprolactone have been analyzed by using microwave spectroscopy and quantum chemical calcula- tions. Two conformers were detected in a supersonic jet ex- pansion, the most stable form being a chair containing the ester group in its rectangular flap. This conformation bene- fits from reduced CH2 bond eclipsing and angle strain, while p-electron delocalization in the ester group is increased. The derived effective structure of the chair form satisfactorily agrees with the calculated near-equilibrium structure. A twist-boat conformer was also identified (9.4 kJ mol � 1 higher in energy at CCSD(T)/aug-cc-pVTZ level), and was located in the boat-twist-boat pseudorotation cycle of the seven-mem- bered ring. Three other low-energy conformers were investi- gated and characterized in terms of the four puckering coor- dinates of the seven-membered ring. Potential interconver- sions in the four-dimensional conformation space are also discussed.

Dirac-exact relativistic methods, i.e., 2- or 1-component methods which exactly reproduce the one-electron energies of the original 4-component Dirac method, have established a standard for reliable relativistic quantum chemical calculations targeting medium- and large-sized molecules. Their development was initiated and facilitated in the late 1990s by Dyall's development of the normalized elimination of the small component (NESC). Dyall's work has fostered the conversion of NESC and related (later developed) methods into routinely used, multipurpose Dirac-exact methods by which energies, first-order, and second-order properties can be calculated at computational costs, which are only slightly higher than those of nonrelativistic methods. This review summarizes the development of a generally applicable 1-component NESC algorithm leading to the calculation of reliable energies, geometries, electron density distributions, electric moments, electric field gradients, hyperfine structure constants, contact densities and Mossbauer isomer shifts, nuclear quadrupole coupling constants, vibrational frequencies, infrared intensities, and static electric dipole polarizabilities. In addition, the derivation and computational possibilities of 2-component NESC methods are discussed and their use for the calculation of spin-orbit coupling (SOC) effects in connection with spin-orbit splittings and SOC-corrected energies are demonstrated. The impact of scalar relativistic and spin-orbit effects on molecular properties is presented. WIREs Comput Mol Sci 2014, 4:436–467. Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

The normalized elimination of the small component method is a first principles two-component relativistic approach that leads to the Dirac-exact description of one-electron systems. Therefore, it is an ideal starting point for developing procedures, by which first- and second-order response properties can be routinely calculated. We present algorithms and methods for the calculation of molecular response properties such as geometries, dipole moments, hyperfine structure constants, vibrational frequencies and force constants, electric polarizabilities, infrared intensities and so forth. The described formalisms are applied to molecules containing mercury and other heavy elements, which require a relativistic treatment. Perspectives for the future development and application of Dirac-exact methods are outlined. © 2013 Wiley Periodicals, Inc.

Multireference averaged quadratic coupled cluster (MRAQCC) (4,5)/cc-pVTZ calculations predict that bond pseudorotation (BPR) in the first excited singlet state of the cyclopentadienyl cation (CPC) proceeds with a barrier of just 0.35 kcal/mol, where five dienylic forms present the minima and five allylic forms the transition states of the pseudorotation process. Vibrational and entropic corrections revert the order of stabilities and lead to a Δ G(298) of just 0.05 kcal/mol indicating that BPR is unhindered at room temperature. The description of the CPC ring in terms of curvilinear deformation coordinates (seven for C5, seven for X5, and three coupling coordinates) make it possible to explore both the six-dimensional (6D) Jahn-Teller and the 8D pseudo-Jahn-Teller space and assess the importance of Jahn–Teller and pseudo-Jahn–Teller deformations of the CPC ring. The latter dominate the ring deformations along the BPR path. The only somewhat larger Jahn–Teller contribution results from a E-symmetrical CCH bending motion. For the perhalogenated CPCs, the dominance of the pseudo-Jahn–Teller effect increases, however, the total deformation of the D5h-symmetrical ring decreases and thereby also the stabilization of the 1A1 forms along the BPR path. This leads to a reduction of the BPR barriers to just 0.14 kcal/mol for C5I. For all pentahalogeno CPCs, the dienylic form is more stable both at the energy and free energy level. The use of curvilinear deformation coordinates facilitates the understanding of the electronic features of cyclic (pseudo-) Jahn–Teller systems. © 2012 Wiley Periodicals, Inc.

The low-lying electronic states of NiH and NiAt are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. The potential energy curves as well as the corresponding spectroscopic constants are reported. The results are grossly in good agreement with the available experimental data and should thus be very useful for guiding future experimental measurements. A cross comparison with other nickel monohalides NiX (X = F, Cl, Br, and I) reveals that the change in the spin-orbit splittings when going from lighter to heavier ligands results more from the state interaction than from the relativistic effects of the ligands.

A large number of scalar as well as spinor excited states of OsO(4), in the experimentally accessible energy range of 3-11 eV, have been captured by time-dependent relativistic density functional linear response theory based on an exact two-component Hamiltonian resulting from the symmetrized elimination of the small component. The results are grossly in good agreement with those by the singles and doubles coupled-cluster linear response theory in conjunction with relativistic effective core potentials. The simulated-excitation spectrum is also in line with the available experiment. Furthermore, combined with detailed analysis of the excited states, the nature of the observed optical transitions is clearly elucidated. It is found that a few scalar states of (3)T(1) and (3)T(2) symmetries are split significantly by the spin-orbit coupling. The possible source for the substantial spin-orbit splittings of ligand molecular orbitals is carefully examined, leading to a new interpretation on the primary valence photoelectron ionization spectrum of OsO(4).

Using multiconfiguration quasi-degenerate perturbation theory (MCQDPT), the ground and the low-lying excited states of InH are studied, and the potential energy curves and the spectroscopic constants of the , a 3Π0−,0+,1,2 and A 1Π1 states are obtained. By comparing the result of all-electron basis sets with that of relativistic effective core potential (RECP) basis sets, it is found that the former is better than the latter, especially in describing the A 1Π1 state. The transition properties of the excited states, including the transition dipole moments, the radiative lifetimes and the Franck–Condon factors, are predicted. It is shown that a 3Π0+ and a 3Π1 are long-lived states, while A 1Π1 is a short-lived state.