Improving a Methane C-H Activation Complex by Metal and Ligand Alterations from Computational Results.

We present results for a series of complexes derived from a titanium complex capable of activating C-H bonds under mild conditions (PNP)Ti═CHBu(CHBu), where PNP = N[2-PPr-4-methylphenyl]. In addition to the initial activation of methane, a tautomerization reaction to a terminal methylidene is also explored due to methylidene's potential use as a synthetic starting point. Analogous complexes with other low-cost 3d transition metals were studied, such as scandium, titanium, vanadium, and chromium as both isoelectronic and isocharged complexes.

Water: new aspect of hydrogen bonding in the solid state.

All water-water contacts in the crystal structures from the Cambridge Structural Database with ≤ 4.0 Å have been found. These contacts were analysed on the basis of their geometries and interaction energies from CCSD(T)/CBS calculations.

Inhibition of miR-21 Promotes Cellular Senescence in NT2-Derived Astrocytes.

Astrocytes are the main homeostatic cells in the central nervous system (CNS) that provide mechanical, metabolic, and trophic support to neurons. Disruption of their physiological role or acquisition of senescence-associated phenotype can contribute to the CNS dysfunction and pathology. However, molecular mechanisms underlying the complex physiology of astrocytes are explored insufficiently.

SOX Transcription Factors as Important Regulators of Neuronal and Glial Differentiation During Nervous System Development and Adult Neurogenesis.

The SOX proteins belong to the superfamily of transcription factors (TFs) that display properties of both classical TFs and architectural components of chromatin. Since the cloning of the / genes, remarkable progress has been made in illuminating their roles as key players in the regulation of multiple developmental and physiological processes. SOX TFs govern diverse cellular processes during development, such as maintaining the pluripotency of stem cells, cell proliferation, cell fate decisions/germ layer formation as well as terminal cell differentiation into tissues and organs.

ATP synthase deficiency due to m.8528T>C mutation - a novel cause of severe neonatal hyperammonemia requiring hemodialysis.

Objectives: Hyperammonemia in a newborn is a serious condition, which requires prompt intervention as it can lead to severe neurological impairment and death if left untreated. The most common causes of hyperammonemia in a newborn are acute liver failure and inherited metabolic disorders. Several mitochondrial disorders have been described as a cause of severe neonatal hyperammonemia.

What Is Special about Aromatic-Aromatic Interactions? Significant Attraction at Large Horizontal Displacement.

High-level calculations show that the most stable stacking for benzene-cyclohexane is 17% stronger than that for benzene-benzene. However, as these systems are displaced horizontally the benzene-benzene attraction retains its strength. At a displacement of 5.

How flexible is the water molecule structure? Analysis of crystal structures and the potential energy surface.

Water molecules from crystal structures archived in the CSD show a relatively large range both in the bond angle and bond lengths. High level ab initio calculations at the CCSD(T)/CBS level predicted a possibility for energetically low-cost (±1 kcal mol-1) changes of the bond angle and bond lengths in a wide range, from 96.4° to 112.

Green Light-Responsive CO-Releasing Polymeric Materials Derived from Ring-Opening Metathesis Polymerization.

Carbon monoxide (CO) is an important biological gasotransmitter in living cells. Precise spatial and temporal control over release of CO is a major requirement for clinical application. To date, the most reported carbon monoxide releasing materials use expensive fabrication methods and require harmful and poorly designed tissue-penetrating UV irradiation to initiate the CO release precisely at infected sites.

The Therapeutic Hypothermia in Treatment of Hyperammonemic Encephalopathy due to Urea Cycle Disorders and Organic Acidemias.

Background: Hyperammonemic encephalopathy in newborns with urea cycle disorders and certain organic acidurias can cause severe brain injury, coma and death. Standard therapy includes protein restriction, nitrogen-scavenging drugs, prevention of catabolism and hemodialysis. Neuroprotective hypothermia as part of the treatment has been reported only 3 times.

Client Evaluation of an Interprofessional Urgent Mental Health Care Program.

Urgent psychiatric care programs are hospital- or community-based outpatient services that expedite access to mental health care for high-risk individuals, yet these services are rarely evaluated from the perspectives of clients. A qualitative thematic analysis of 13 participant interviews of a psychiatric urgent care program allowed researchers to address this gap. Communication, responsiveness, and continuous availability were identified as critical in helping clients articulate their perceived self-stigma, needs, and preferences.

Hypogammaglobulinemia and imaging features in a patient with infantile free sialic acid storage disease (ISSD) and a novel mutation in the SLC17A5 gene.

Background Infantile free sialic acid storage disease (ISSD) is a severe multisystemic disorder characterized by the accumulation of free sialic acid in lysosomes. Case presentation The patient presented prenatally with fetal ascites and large scrotal hernias, without pleural or pericardial effusion. During the infantile period, he was diagnosed with permanent isolated immunoglobulin G (IgG) hypogammaglobulinemia, which thus far has rarely been associated with ISSD.

Methane Activations by Titanium Neopentylidene Complexes: Electronic Resilience and Steric Control.

The titanium neopentylidene complex (PNP)Ti═CHBu(CHBu) (PNP = N[2-PPr-4-methylphenyl]) is capable of activating both sp and sp C-H bonds under mild conditions. In addition to methane C-H activation, competition between the initial hydrogen abstraction reaction to form the methane activation product and the tautomerization reaction of this product to form a terminal methylidene was also explored. Several modifications of the PNP and CHBu ligands were explored to determine the effect of these changes on C-H bond activation.

Unexpected Importance of Aromatic-Aliphatic and Aliphatic Side Chain-Backbone Interactions in the Stability of Amyloids.

The role of aromatic and nonaromatic amino acids in amyloid formation has been elucidated by calculating interaction energies between β-sheets in amyloid model systems using density functional theory (B3LYP-D3/6-31G*). The model systems were based on experimental crystal structures of two types of amyloids: (1) with aromatic amino acids, and (2) without aromatic amino acids. Data show that these two types of amyloids have similar interaction energies, supporting experimental findings that aromatic amino acids are not essential for amyloid formation.

Aggression in psychiatric hospitalizations: a qualitative study of patient and provider perspectives.

Background: When the people hospitalized in psychiatric units demonstrate aggression, it harms individuals and creates legal and financial issues for hospitals. Aggression has been linked to inpatient, clinician and environmental characteristics. However, previous work primarily accessed clinicians' perspectives or administrative data and rarely incorporated inpatients' insights.

Aliphatic-aromatic stacking interactions in cyclohexane-benzene are stronger than aromatic-aromatic interaction in the benzene dimer.

Stacking interactions between cyclohexane and benzene were studied in crystal structures from the Cambridge Structural Database and by ab initio calculations. Calculated at the very accurate CCSD(T)/CBS level of theory, the cyclohexane-benzene interaction energy is -3.27 kcal mol, which is significantly stronger than the interaction in the benzene dimer (-2.

Hyperinsulinism-hyperammonemia syndrome: a de novo mutation of the GLUD1 gene in twins and a review of the literature.

Hyperinsulinism-hyperammonemia (HI/HA) syndrome is a rare autosomal dominant disease characterized by recurrent hypoglycemia and persistent mild elevation of plasma ammonia. HI/HA syndrome is one of the more common forms of congenital hyperinsulinism (CHI), caused by activating mutations within the GLUD1 gene that encodes the mitochondrial enzyme glutamate dehydrogenase (GDH). We report here on monozygotic twin girls presented with fasting- and protein-induced hypoglycemia and mild persistent hyperammonemia.

Stacking of metal chelates with benzene: can dispersion-corrected DFT be used to calculate organic-inorganic stacking?

CCSD(T)/CBS energies for stacking of nickel and copper chelates are calculated and used as benchmark data for evaluating the performance of dispersion-corrected density functionals for calculating the interaction energies. The best functionals for modeling the stacking of benzene with the nickel chelate are M06HF-D3 with the def2-TZVP basis set, and B3LYP-D3 with either def2-TZVP or aug-cc-pVDZ basis set, whereas for copper chelate the PBE0-D3 with def2-TZVP basis set yielded the best results. M06L-D3 with aug-cc-pVDZ gives satisfying results for both chelates.

Stacking of benzene with metal chelates: calculated CCSD(T)/CBS interaction energies and potential-energy curves.

Accurate values for the energies of stacking interactions of nickel- and copper-based six-membered chelate rings with benzene are calculated at the CCSD(T)/CBS level. The results show that calculations made at the ωB97xD/def2-TZVP level are in excellent agreement with CCSD(T)/CBS values. The energies of [Cu(C3H3O2)(HCO2)] and [Ni(C3H3O2)(HCO2)] chelates stacking with benzene are -6.

What are the preferred horizontal displacements of aromatic-aromatic interactions in proteins? Comparison with the calculated benzene-benzene potential energy surface.

The data from protein structures from the Protein Data Bank and quantum chemical calculations indicate the importance of aromatic-aromatic interactions at large horizontal displacements (offsets). The protein stacking interactions of the phenylalanine residue show preference for large offsets (3.5-5.

Influence of supramolecular structures in crystals on parallel stacking interactions between pyridine molecules.

Parallel stacking interactions between pyridines in crystal structures and the influence of hydrogen bonding and supramolecular structures in crystals on the geometries of interactions were studied by analyzing data from the Cambridge Structural Database (CSD). In the CSD 66 contacts of pyridines have a parallel orientation of molecules and most of these pyridines simultaneously form hydrogen bonds (44 contacts). The geometries of stacked pyridines observed in crystal structures were compared with the geometries obtained by calculations and explained by supramolecular structures in crystals.

Stacking interactions of Ni(acac) chelates with benzene: calculated interaction energies.

Piling 'em up: The stacking energy of the [Ni(acac)2]/benzene system is calculated at local CCSD(T) level and is in good agreement with the values obtained with the SCS-MP2 method. Energies calculated with several DFT-D methods are somewhat overestimated. The calculated stacking energy of the [Ni(acac)2]/benzene system is significantly stronger than that of the benzene dimer.

Parallel interactions at large horizontal displacement in pyridine-pyridine and benzene-pyridine dimers.

A study of crystal structures from the Cambridge Structural Database (CSD) and DFT calculations reveals that parallel pyridine-pyridine and benzene-pyridine interactions at large horizontal displacements (offsets) can be important, similar to parallel benzene-benzene interactions. In the crystal structures from the CSD preferred parallel pyridine-pyridine interactions were observed at a large horizontal displacement (4.0-6.

The influence of water molecule coordination to a metal ion on water hydrogen bonds.

The geometry of hydrogen bonds in the crystal structures from the Cambridge Structural Database and calculated data show that water coordination to a metal ion has a remarkable influence on hydrogen bonds. The calculated energies of hydrogen bonds of coordinated water are much stronger, even if the aqua complex is neutral.