Structural Phase Transitions and Magnetic Superexchange in MI AgII F3 Perovskites at High Pressure.

Pressure-induced phase transitions of MI AgII F3 perovskites (M=K, Rb, Cs) have been predicted theoretically for the first time for pressures up to 100 GPa. The sequence of phase transitions for M=K and Rb consists of a transition from orthorhombic to monoclinic and back to orthorhombic, associated with progressive bending of infinite chains of corner-sharing [AgF6 ]4- octahedra and their mutual approach through secondary Ag⋅⋅⋅F contacts. In stark contrast, only a single phase transition (tetragonal→triclinic) is predicted for CsAgF3 ; this is associated with substantial deformation of the Jahn-Teller-distorted first coordination sphere of AgII and association of the infinite [AgF6 ]4- chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF3 hosts lattices.

Beyond Oxides: Nitride as a Ligand in a Neutral IrIX NO3 Molecule Bearing a Transition Metal at High Oxidation State.

Theoretical calculations utilizing relativistic ZORA Hamiltonian point to the conceivable existence of an IrNO3 molecule in C3v geometry. This minimum is shown to correspond to genuine nonavalent iridium nitride trioxide, which is a neutral analogue of cationic [IrO4 ]+ species detected recently. Despite the presence of nitride anion, the molecule is protected by substantial barriers exceeding 200 kJ mol-1 against transformations leading, for example, to global minimum (O=)2 Ir-NO, which contains metal at a lower formal oxidation state.

Is the choice of a standard zeroth-order hamiltonian in CASPT2 ansatz optimal in calculations of excitation energies in protonated and unprotonated schiff bases of retinal?

To account for systematic error of CASPT2 method empirical modification of the zeroth-order Hamiltonian with Ionization Potential-Electron Affinity (IPEA) shift was introduced. The optimized IPEA value (0.25 a.u.), called standard IPEA (S-IPEA), was recommended but due to its unsatisfactory performance in multiple metallic and organic compounds it has been questioned lately as a general parameter working properly for all molecules under CASPT2 study. As we are interested in Schiff bases of retinal, an important question emerging from this conflict of choice, to use or not to use S-IPEA, is whether the introduction of the modified zeroth-order Hamiltonian into CASPT2 ansatz does really improve their energetics. To achieve this goal, we assessed an impact of the IPEA shift value, in a range of 0-0.35 a.u., on vertical excitation energies to low-lying singlet states of two protonated (RPSBs) and two unprotonated (RSBs) Schiff bases of retinal for which experimental data in gas phase are available. In addition, an effect of geometry, basis set, and active space on computed VEEs is also reported. We find, that for these systems, the choice of S-IPEA significantly overestimates both S0 →S1 and S0 →S2 energies and the best theoretical estimate, in reference to the experimental data, is provided with either unmodified zeroth-order Hamiltonian or small value of the IPEA shift in a range of 0.05-0.15 a.u., depending on active space and basis set size, equilibrium geometry, and character of the excited state. © 2018 Wiley Periodicals, Inc.

Determining the optimal treatment target in patients with ulcerative colitis: rationale, design, protocol and interim analysis for the randomised controlled VERDICT trial.

INTRODUCTION: Symptoms, endoscopy and histology have been proposed as therapeutic targets in ulcerative colitis (UC). Observational studies suggest that the achievement of histologic remission may be associated with a lower risk of complications, compared with the achievement of endoscopic remission alone. The actiVE ulcerative colitis, a RanDomIsed Controlled Trial (VERDICT) aims to determine the optimal treatment target in patients with UC. METHODS AND ANALYSIS: In this multicentre, prospective randomised study, 660 patients with moderate to severe UC (Mayo rectal bleeding subscore [RBS] ≥1; Mayo endoscopic score [MES] ≥2) are randomly assigned to three treatment targets: corticosteroid-free symptomatic remission (Mayo RBS=0) (group 1); corticosteroid-free endoscopic remission (MES ≤1) and symptomatic remission (group 2); or corticosteroid-free histologic remission (Geboes score <2B.0), endoscopic remission and symptomatic remission (group 3). Treatment is escalated using vedolizumab according to a treatment algorithm that is dependent on the patient's baseline UC therapy until the target is achieved at weeks 16, 32 or 48. The primary outcome, the time from target achievement to a UC-related complication, will be compared between groups 1 and 3 using a Cox proportional hazards model. ETHICS AND DISSEMINATION: The study was approved by ethics committees at the country level or at individual sites as per individual country requirements. A full list of ethics committees is available on request. Study results will be disseminated in peer-reviewed journals and at scientific meetings. TRIAL REGISTRATION NUMBER: EudraCT: 2019-002485-12; NCT04259138.

Quadripartite bond length rule applied to two prototypical aromatic and antiaromatic molecules.

CONTEXT: In 2000, a remarkably simple relationship was introduced, which connected the calculated geometries of isomolecular states of three different multiplicities. These encompass a ground single state, the first excited triplet state, as well as related radical anion and radical cation. The rule allows the prediction of the geometry of one of the species if the three remaining ones are known. Here, we verify the applicability of this bond length rule for two small planar cyclic organic molecules, i.e., benzene and cyclobutadiene, which stand as prototypical examples of, respectively, aromatic and antiaromatic systems. We see that the rule works fairly well to benzene, and it works independently for quinoid as well as for anti-quinoid minima, despite the fact that radical anion species poses challenges for correct theoretical description. METHODS: To obtain chosen electronic state equilibrium geometries, three types of computational approaches were utilized: fast and efficient density functional theory DFT, the coupled cluster method CC2, the complete active space self-consistent field (CASSCF) approach, and the most accurate but also resource-consuming perturbation theory with multireference wavefunction (CASPT2) with a default value and without IPEA-shift. Dunning and co-workers correlation-consistent basis sets (aug-)cc-pVXZ (X = D, T, Q) were employed. Gaussian 16 revision A.03, Turbomole 7.1, and Molcas 8.0 computational software were used.

PtX as the limit of high oxidation states in oxide-nitride species.

A series of pentaatomic species has been investigated theoretically with relativistic DFT using the M06-L functional with both ZORA scalar relativistic correction, and including spin-orbit coupling effects. The distorted quasi-octahedral local minima for PtNO3+, PtN2O2 and PtN3O- corresponding to decavalent Pt were found to be unstable with respect to the elimination of O2, NO or N2. However, barriers surrounding these minima suggest that these species could be achieved under low-temperature conditions, similar to what was predicted for PtO42+ dications. Decavalent platinum sets the upper limit for high oxidation states of the chemical elements.

The high covalence of metal-ligand bonds as stability limiting factor: the case of Rh(IX)O4+ and Rh(IX)NO3.

Rhodium, a 4d transition metal and a lighter analogue of iridium, is known to exhibit its highest VIth oxidation state in RhF6 molecule. In this report, the stability and decomposition pathways of two species containing rhodium at a potentially formal +IX oxidation state, [RhO4]+ and RhNO3, have been investigated theoretically within the framework of the relativistic two-component Hamiltonian calculations. Possible rearrangement into isomers featuring lower formal oxidation numbers has been explored. We found that both species studied are metastable with respect to elimination of O2 or NO. However, the local minima containing Rh(IX) are protected by sufficient energy barriers on the decomposition pathway, and they could in principle be prepared. The analysis of a broader set of compounds containing group 8 and 9 metals in high formal oxidation states that correspond to the group number showed that, in contrast to a standard trend, the limits of formally attainable oxidation state correlate with high level of covalent bonding character in the complexes studied.

[Knowledge of the term and methods of alternative medicine in the example of the patients of one bioresonance practice]. / Znajomosc pojecia i metod medycyny alternatywnej na przykladzie populacji korzystajacej z uslug jednego z gabinetów biorezonansu.

UNLABELLED: The growing number of patients of various kinds of unconventional medicine poses a question as to the reason of taking up such treatments. Do such people know whether the methods of treatment they opt for are scientifically proven? Aim of the study was to test the knowledge among patients of bioresonance practice on methods of alternative medicine and to determine the break down of those patients based on their sex, age and the level of education. MATERIAL AND METHODS: 152 patients of bioresonance practice were asked to fill in an anonymous questionnaire. The respondents were to choose unconventional methods of treatment from the list of ten. Afterwards they were asked to answer 4 questions that referred to the opinion on and experience with alternative medicine. Chi square test and t-Student test were used to find statistical significance. RESULTS: The level of education is the only factor which determines the knowledge of the methods of alternative medicine. What is more, a mere third of patients realized that they used such a method. For one in four respondents it did not matter whether the method was properly tested and scientifically proven. Some 7.5% did not understand the meaning of the term 'alternative medicine' and did not differentiate such methods from conventional ones. CONCLUSIONS: There is quite a high percentage of people who do not know that the methods of treatment selected are unconventional. The second alarming fact is that the people who decide on treatment in an unconventional way are not concerned with any scientific evidence. The knowledge of the term and methods of alternative medicine increases with the education level.

Influence of long-term treatment with tuftsin analogue TP-7 on the anxiety-phobic states and body weight.

TP-7 is a synthetic analogue of tuftsin. It has a structure of tuftsin, to which three natural L-amino-acids Pro-Gly-Pro are attached. This heptapeptide improves learning and memorization and causes antidepressant and anxiolytic effect. It is possible to use TP-7 in the future to optimize cognitive functions and as a potential new anxioselective, fast-acting and easy-dosed drug. Therefore, it was purposeful to study such properties of the heptapeptide as its influence on anxiety-fear and body weight under a long-term treatment regimen. The experiment was performed on 24 preselected Wistar rats with the use of Rodina's method. There were three experimental groups of animals with high initial emotional reactivity: passive control group (P), active control group (A, receiving distilled water) and group treated with TP-7 at the dose of 0.3 mg/kg (T). The rats of A and T groups received intraperitoneal injections every day. The experiments were conducted 15 min after the administration of the drug, one and two days after initial testing day, then 1, 2, 3 and 4 weeks after that. The heptapeptide reduced the anxiety-phobic states significantly starting from the second day of drug application. The observed effects persisted throughout four weeks of the experiment, which confirmed effective long-term anxiolytic properties of the heptapeptide. TP-7 did not cause any changes in the body mass by itself.

Assessment of Approximate Coupled-Cluster and Algebraic-Diagrammatic-Construction Methods for Ground- and Excited-State Reaction Paths and the Conical-Intersection Seam of a Retinal-Chromophore Model.

As a minimal model of the chromophore of rhodopsin proteins, the penta-2,4-dieniminium cation (PSB3) poses a challenging test system for the assessment of electronic-structure methods for the exploration of ground- and excited-state potential-energy surfaces, the topography of conical intersections, and the dimensionality (topology) of the branching space. Herein, we report on the performance of the approximate linear-response coupled-cluster method of second order (CC2) and the algebraic-diagrammatic-construction scheme of the polarization propagator of second and third orders (ADC(2) and ADC(3)). For the ADC(2) method, we considered both the strict and extended variants (ADC(2)-s and ADC(2)-x). For both CC2 and ADC methods, we also tested the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) variants. We have explored several ground- and excited-state reaction paths, a circular path centered around the S1/S0 surface crossing, and a 2D scan of the potential-energy surfaces along the branching space. We find that the CC2 and ADC methods yield a different dimensionality of the intersection space. While the ADC methods yield a linear intersection topology, we find a conical intersection topology for the CC2 method. We present computational evidence showing that the linear-response CC2 method yields a surface crossing between the reference state and the first response state featuring characteristics that are expected for a true conical intersection. Finally, we test the performance of these methods for the approximate geometry optimization of the S1/S0 minimum-energy conical intersection and compare the geometries with available data from multireference methods. The present study provides new insight into the performance of linear-response CC2 and polarization-propagator ADC methods for molecular electronic spectroscopy and applications in computational photochemistry.