Pretreatment of TiO2-supported Fe, Co and Ru catalysts: an in situ powder diffraction study.

There has been increasing interest in in situ or in operando studies of heterogeneous catalysts in the past two decades. This drive has seen the invention and modification of analytical instruments that allow for the investigation of certain catalyst properties under realistic reaction conditions. Powder X-ray diffraction has been used to investigate the structural properties of heterogeneous catalysts for many years and has not escaped the in situ revolution. Reaction cells have been designed, tested and used, both on laboratory-based instruments and at neutron and synchrotron facilities. The experiments performed at these institutions have yielded information regarding the active solid-state phases of heterogeneous catalysts used in a multitude of different reactions, often with surprising results. Little attention has, however, been given to the use of the technique during catalyst preparation and its importance in such investigations is highlighted in this work in conjunction with whole-pattern Rietveld refinement techniques. This study focused on the use of in situ PXRD as a means of monitoring the structural properties of TiO2-supported metal catalysts during heat treatment, or calcination, and reduction, or activation. The TiO2 supports included Degussa P25, Sigma-Aldrich anatase and nanosized anatase prepared using a sol gel method. The metals of interest were those shown to be active in the Fischer-Tropsch reaction, namely Fe, Co and Ru. In situ heat treatment of the supports was used to measure thermal stability and to monitor the anatase to rutile phase transition in terms of concentration and particle size. We were able to show that the Sigma anatase was the most stable of the three supports, while Degussa P25 was the least stable. By calculating the rates of change of concentration between each collection, a reasonably accurate determination of the phase transition temperature in each support was possible. Our results confirmed the growth of anatase particles before the phase transition and the rapid agglomeration of rutile particles after the transition, both of which had been discussed elsewhere. During the course of the heat treatment of the supports, mathematical corrections were developed to eliminate the effects of sample penetration that affected the quantitative phase analysis. In situ heat treatment experiments were employed to determine the ideal calcination temperature of each catalyst in terms of maximum metal oxide concentration and particle size. By using an internal standard (spike), we were able to monitor the crystallization of the amorphous metal precursors to form supported metal oxides. The addition of the metal oxide phases was shown to affect the anatase to rutile phase transition in various ways, depending on the support and metal oxide species. The effect of excessive heat treatment was also investigated and provided insight into the formation of metal titanates. Using the rates of change of concentration between collections, we were able to determine if anatase and/or rutile took part in the formation of the metal titanates. In situ activation experiments were conducted in order to determine the ideal reduction procedure for each catalyst. The reduction results confirmed that the concentration of H2 in H2/N2 gas mixtures had an effect on the reduction profile of a Degussa-supported Fe catalyst. We were able to monitor the formation of amorphous phases, which form during the second stages of reduction of both hematite and cobalt(II) oxide. It is thought that these amorphous materials represent the interfacial region between the support and the metal particles. This is the first time that the quantification of this interface material has been performed and its presence has been used to explain the poor degrees of reducibility observed for these types of catalysts. We found that the Ru and Co particles were less sensitive to elevated reduction temperatures than the Fe particles, which demonstrated a massive degree of sintering even at low temperatures

Poly[1,4-bis­(ammonio­meth­yl)cyclo­hexane [di-μ-iodido-diiodido­plumbate(II)]]

The title compound, {(C8H20N2)[PbI4]}n, is an inorganic–organic hybrid. The structure is composed of alternate layers of two-dimensional corner-sharing PbI6 octa­hedra ( symmetry) and 1,4-bis­(ammonio­meth­yl)cyclo­hexane cations ( symmetry) extending parallel to the bc plane. The cations inter­act with the inorganic layer via N—H⋯I hydrogen bonding in the right-angled halogen sub-type of the terminal halide hydrogen-bonding motif

Poly[1,4-bis­(ammonio­meth­yl)cyclo­hexane [di-μ-bromido-dibromido­plumbate(II)]]

The title compound, {(C8H20N2)[PbBr4]}n, crystallizes as an inorganic–organic hybrid with alternating layers of diammonium cations and two-dimensional corner-sharing PbBr6 octa­hedra extending parallel to the bc plane, which are eclipsed relative to one another. Both PbBr6 octa­hedra and the organic cation exhibit symmetry. The cations inter­act via N—H⋯Br hydrogen bonding in the right-angled halogen sub-type of the terminal halide hydrogen-bonding motif

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Pf7: an open dataset of Plasmodium falciparum genome variation in 20,000 worldwide samples

We describe the MalariaGEN Pf7 data resource, the seventh release of Plasmodium falciparum genome variation data from the MalariaGEN network.  It comprises over 20,000 samples from 82 partner studies in 33 countries, including several malaria endemic regions that were previously underrepresented.  For the first time we include dried blood spot samples that were sequenced after selective whole genome amplification, necessitating new methods to genotype copy number variations.  We identify a large number of newly emerging crt mutations in parts of Southeast Asia, and show examples of heterogeneities in patterns of drug resistance within Africa and within the Indian subcontinent.  We describe the profile of variations in the C-terminal of the csp gene and relate this to the sequence used in the RTS,S and R21 malaria vaccines.  Pf7 provides high-quality data on genotype calls for 6 million SNPs and short indels, analysis of large deletions that cause failure of rapid diagnostic tests, and systematic characterisation of six major drug resistance loci, all of which can be freely downloaded from the MalariaGEN website

Poly[1,4-bis(ammoniomethyl)cyclohexane [di-&amp;#956;-chlorido-dichloridoplumbate(II)]]

The title compound, {(C8H20N2)[PbCl4]}n, crystallizes as an layered inorganic&amp;#8211;organic hybrid perovskite-type structure. Corner-sharing PbCl6 octahedra extend parallel to the ac plane. Adjacent layers are staggered relative to one another, with diammonium cations separating these layers. The cations exhibit overline{1} symmetry and interact with the inorganic sheets via N&amp;#8212;H...Cl hydrogen bonding in the right-angled halogen sub-type of the terminal halide hydrogen-bonding motif