Hydration of a 2D Supramolecular Assembly: Bitartrate on Cu(110).

Hydration layers play a key role in many technical and biological systems, but our understanding of these structures remains very limited. Here, we investigate the molecular processes driving hydration of a chiral metal-organic surface, bitartrate on Cu(110), which consists of hydrogen-bonded bitartrate rows separated by exposed Cu. Initially water decorates the metal channels, hydrogen bonding to the exposed O ligands that bind bitartrate to Cu, but does not wet the bitartrate rows. At higher temperature, water inserts into the structure, breaks the existing intermolecular hydrogen bonds, and changes the adsorption site and footprint. Calculations show this process is driven by the creation of stable adsorption sites between the carboxylate ligands, to allow hydration of O-Cu ligands within the interior of the structure. This work suggests that hydration of polar metal-adsorbate ligands will be a dominant factor in many systems during surface hydration or self-assembly from solution.

Oriented Two-Dimensional Porous Organic Cage Crystals.

The formation of two-dimensional (2D) oriented porous organic cage crystals (consisting of imine-based tetrahedral molecules) on various substrates (such as silicon wafers and glass) by solution-processing is reported. Insight into the crystallinity, preferred orientation, and cage crystal growth was obtained by experimental and computational techniques. For the first time, structural defects in porous molecular materials were observed directly and the defect concentration could be correlated with crystal growth rate. These oriented crystals suggest potential for future applications, such as solution-processable molecular crystalline 2D membranes for molecular separations.

Effectiveness of nitric oxide agents in preventing the early onset of pre-eclampsia and possible modification of metabolic factors in high-risk pregnancies: a systematic review protocol.

OBJECTIVES: To determine the effectiveness of nitric oxide agents in modifying the metabolic factors of pre-eclampsia and its effectiveness in preventing the onset of pre-eclampsia in high-risk pregnancies. INTRODUCTION: Pre-eclampsia is a major cause of maternal death during the prenatal and neonatal periods. Nitric oxide is a vasodilator and platelet aggregation inhibitor responsible for the vascular adaptation of the placenta. Although various studies have established that nitric oxide is effective in preventing complications from pre-eclampsia, there is limited evidence to show that administering nitric oxide agents to high-risk women before 20 weeks' gestation will prevent the onset of pre-eclampsia. INCLUSION CRITERIA: This review will consider randomized controlled trials that compare nitric oxide donors and precursors with a placebo or no intervention on pregnant women (18 to 44 years) with ≤ 20-week gestational age that are at high risk of pre-eclampsia. The primary outcome of interest will be the onset of pre-eclampsia. Secondary outcomes include increased systolic and diastolic blood pressure, elevated asymmetric dimethylarginine levels, decreased endothelial nitric oxide synthase activity, reduced maternal placental vasculature, and abnormal Doppler ultrasound waveforms. METHODS: Data sources will be drawn up from MEDLINE, CINAHL, ProQuest (Health and Medicine), and Web of Science from inception till current date. No language restrictions will be applied in the search strategy. Selected studies will be assessed against the JBI critical appraisal checklist, and the certainty of evidence and strength of recommendations from findings will also be ascertained. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42018099298.

Mind your Language: Discursive Practices Produce Unequal Power and Control Over Infectious Disease: A Critical Discourse Analysis.

BACKGROUND: Power, socioeconomic inequalities, and poverty are recognized as some of the fundamental determinants of differences in vulnerability of societies to infectious disease threats. The economic south is carrying a higher burden than those in the economic north. This raises questions about whether social preventions and biomedical preventions for infectious disease are given equal consideration, and about social institutions and structures that frame the debate about infectious disease. This article examines how institutionalized ways of talking about infectious disease reinforces, creates, and sustains health inequalities. METHODS: Critical discourse analysis was considered to be epistemologically and ontologically consistent with the aims and context of this study. RESULTS: The study examined three types of infectious disease: • Emerging infectious diseases/pathogens • Neglected tropical diseases • Vector-borne infections. Examination revealed that poverty is the most common determinant of all three. CONCLUSIONS: A sustainable reduction in infectious disease in the southern countries is most likely to be achieved through tackling socioeconomic determinants. There is a need for a change in the discourse on infectious disease, and adopt a discourse that promotes self-determination, rather than one that reinforces the hero-victim scenario and power inequalities.

Racemic versus enantiopure alanine on Cu(110): an experimental study.

The adsorption of racemic alanine on the Cu(110) surface has been compared to that of enantiopure alanine using low-energy electron diffraction (LEED), reflection absorption infrared spectroscopy (RAIRS), and scanning tunneling microscopy (STM). No evidence of chiral resolution at the surface was observed for the racemic system, indicating that the formation of separate enantiopure areas is not preferred. Also, in contrast to the enantiopure system, no chirally organized phase was observed for the racemic system. LEED shows that both systems display a common (3 x 2) phase at high coverage. However, the pathway and kinetic barriers to this phase differ markedly for the racemic and the enantiopure systems, with the racemic (3 x 2) appearing at a temperature that is more than 100 K below that required for the enantiopure system. In addition, we report intriguing complexities for the (3 x 2) LEED structure that is ubiquitous in amino acid/Cu(110) systems. First, a common (3 x 2) pattern with a zigzag distortion can be associated with both the racemic and enantiopure systems. For the racemic system, the coverage can be increased further to give a "true" (3 x 2) LEED pattern, which is a transformation that is impossible to enact for the enantiopure system. Most importantly, STM images of the "distorted" and "true" (3 x 2) structures created in the racemic system show subtle differences with neither arrangement being fully periodic over distances greater than a few molecules. Thus, the (3 x 2) phase appears to be more complicated than at first indicated and will require more complex models for a full interpretation.

Molecular structures of the 1,6-disubstituted triptycenes Sb2(C6F4)3 and Bi2(C6F4)3 using gas-phase electron diffraction and ab initio and DFT calculations.

The structures of the D(3h)-symmetric molecules dodecafluoro-1,6-distibatriptycene and dodecafluoro-1,6-dibismatriptycene [Z2(C6F4)3 (Z = Sb, Bi)] have been determined in the gas phase by electron diffraction, using the SARACEN method, with restraints obtained from quantum chemical calculations. Several methods of ab initio and density functional theory geometry calculations have been performed and recommendations made as to their relative suitabilities for determining the structures of such species. Calculations using the MP2 method with a small-core pseudopotential (aug-cc-pVQZ-PP) on the Sb and Bi atoms and the 6-311G* basis set on the light atoms were found to give the closest correlation with the experimental results for both molecules. Differences in structure were found depending on whether a large-core or small-core pseudopotential was used on the heavy atoms.