Microwave digestion of zircon with ammonium acid fluoride: derivation of kinetic parameters from non-isothermal reaction data

Zircon is notoriously inert. Aggressive processing methods such as alkaline fusion are conventionally used to extract zirconium values from the mineral. In this study results are presented with respect to microwave digestion of zircon using ammonium acid fluoride (NH4F·1.5HF). Two distinct experimental methods were used. In the first method the reaction was followed in the temperature range of 100 to 200 °C, for a full reaction period of 60 min at each temperature. The secondmethod comprised successive digestion periods interrupted bywashing and re-introduction of fresh acid fluoride at a series of reaction temperatures varying between 120 and 240 °C. Complete digestion was achieved with the latter technique. The kinetics is shown to be controlled by product-layer diffusion. The two data sets were combined to derive consistent temperature-dependent kinetic parameters. A facile numerical technique for extracting these parameters from the experimental data is used.The Advanced Metals Initiative of the Department of Science and Technology of South Africa.http://www.elsevier.com/locate/ijimprohb201

Prospective comparative study of spiral computer tomography and magnetic resonance imaging for detection of hepatocellular carcinoma

BACKGROUND: Hepatocellular carcinoma (HCC) is often detected at a relatively late stage when tumour size prohibits curative surgery. Screening to detect HCC at an early stage is performed for patients at risk. AIM: The aim of this study was to compare prospectively the diagnostic accuracy and classification for management of the two state of the art secondline imaging techniques: triphasic spiral computer tomography (CT) and super paramagnetic iron oxide (SPIO) enhanced magnetic resonance imaging (MRI). PATIENTS: Sixty one patients were evaluated between January 1996 and January 1998. Patients underwent CT and MRI within a mean interval of 6.75 days. METHODS: CT and MRI were evaluated blindly for the presence and number of lesions, characterisation of these lesions, and classification for management. For comparison of the data on characterisation, the CT and MRI findings were compared with histopathological studies of the surgical specimens and/or follow up imaging. Data of patients not lost to follow up were available to January 2001. RESULTS: SPIO enhanced MRI detected more lesions and overall smaller lesions than triphasic spiral CT (number of lesions 189 v 124; median diameter 1.0 v 1.8 cm; Spearman rank's correlation coefficient 0.63, p<0.001). There was no significant difference in accuracy between CT and MRI for lesion characterisation. The agreement in classification for management was very good (weighted kappa 0.91, 95% CI 0.83-0.99). CONCLUSION: SPIO enhanced MRI detects more and smaller lesions, but both techniques are comparable in terms of classification for management. SPIO enhanced MRI may be preferred as there is no exposure to ionising radiation

Estimating North American background ozone in U.S. surface air with two independent global models: Variability, uncertainties, and recommendations

Accurate estimates for North American background (NAB) ozone (O3) in surface air over the United States are needed for setting and implementing an attainable national O3 standard. These estimates rely on simulations with atmospheric chemistry-transport models that set North American anthropogenic emissions to zero, and to date have relied heavily on one global model. We examine NAB estimates for spring and summer 2006 with two independent global models (GEOS-Chem and GFDL AM3). We evaluate the base simulations, which include North American anthropogenic emissions, with mid-tropospheric O3 retrieved from space and ground-level O3 measurements. The models often bracket the observed values, implying value in developing a multi-model approach to estimate NAB O3. Consistent with earlier studies, the models robustly simulate the largest nation-wide NAB levels at high-altitude western U.S. sites (seasonal average maximum daily 8-h values of ∼40–50 ppb in spring and ∼25–40 ppb in summer) where it correlates with observed O3. At these sites, a 27-year GFDL AM3 simulation simulates observed O3 events above 60 ppb and indicates that year-to-year variations in NAB O3 influence their annual frequency (with NAB contributing 50–60 ppb or more during individual events). During summer over the eastern United States (EUS), when photochemical production from regional anthropogenic emissions peaks, NAB is largely uncorrelated with observed values and it is lower than at high-altitude sites (average values of ∼20–30 ppb). Four processes contribute substantially to model differences in specific regions and seasons: lightning NOx, biogenic isoprene emissions and chemistry, wildfires, and stratosphere-to-troposphere transport. Differences in the representations of these processes within the GFDL AM3 and GEOS-Chem models contribute more to uncertainty in NAB estimates, particularly in spring when NAB is highest, than the choice of horizontal resolution within a single model (GEOS-Chem). We propose that future efforts seek to constrain these processes with targeted analysis of multi-model simulations evaluated with observations of O3 and related species from multiple platforms, and thereby reduce the error on NAB estimates needed for air quality planning.Engineering and Applied Science

Exclusive measurements of quasi-free proton scattering reactions in inverse and complete kinematics

Quasi-free scattering reactions of the type (p, 2p) were measured for the first time exclusively in complete and inverse kinematics, using a 12C beam at an energy of ~400 MeV/u as a benchmark. This new technique has been developed to study the single-particle structure of exotic nuclei in experiments with radioactive-ion beams. The outgoing pair of protons and the fragments were measured simultaneously, enabling an unambiguous identification of the reaction channels and a redundant measurement of the kinematic observables. Both valence and deeply-bound nucleon orbits are probed, including those leading to unbound states of the daughter nucleus. Exclusive (p, 2p) cross sections of 15.8(18) mb, 1.9(2) mb and 1.5(2) mb to the low-lying 0p-hole states overlapping with the ground state (3/2-) and with the bound excited states of 11B at 2.125 MeV (1/2-) and 5.02 MeV (3/2-), respectively, were determined via γ-ray spectroscopy. Particle-unstable deep-hole states, corresponding to proton removal from the 0s-orbital, were studied via the invariant-mass technique. Cross sections and momentum distributions were extracted and compared to theoretical calculations employing the eikonal formalism. The obtained results are in a good agreement with this theory and with direct-kinematics experiments. The dependence of the proton-proton scattering kinematics on the internal momentum of the struck proton and on its separation energy was investigated for the first time in inverse kinematics employing a large-acceptance measurement

Poor outcomes in both infection and colonization with carbapenem-resistant Enterobacterales

Objectives: To describe the epidemiology of patients with nonintestinal carbapenem-resistant Enterobacterales (CRE) colonization and to compare clinical outcomes of these patients to those with CRE infection. Design: A secondary analysis of Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae 2 (CRACKLE-2), a prospective observational cohort. Setting: A total of 49 US short-term acute-care hospitals. Patients: Patients hospitalized with CRE isolated from clinical cultures, April, 30, 2016, through August 31, 2017. Methods: We described characteristics of patients in CRACKLE-2 with nonintestinal CRE colonization and assessed the impact of site of colonization on clinical outcomes. We then compared outcomes of patients defined as having nonintestinal CRE colonization to all those defined as having infection. The primary outcome was a desirability of outcome ranking (DOOR) at 30 days. Secondary outcomes were 30-day mortality and 90-day readmission. Results: Of 547 patients with nonintestinal CRE colonization, 275 (50%) were from the urinary tract, 201 (37%) were from the respiratory tract, and 71 (13%) were from a wound. Patients with urinary tract colonization were more likely to have a more desirable clinical outcome at 30 days than those with respiratory tract colonization, with a DOOR probability of better outcome of 61% (95% confidence interval [CI], 53%-71%). When compared to 255 patients with CRE infection, patients with CRE colonization had a similar overall clinical outcome, as well as 30-day mortality and 90-day readmission rates when analyzed in aggregate or by culture site. Sensitivity analyses demonstrated similar results using different definitions of infection. Conclusions: Patients with nonintestinal CRE colonization had outcomes similar to those with CRE infection. Clinical outcomes may be influenced more by culture site than classification as "colonized"or "infected.

Characteristics of community-Acquired carbapenem-resistant Enterobacterales

Background: Community-Acquired carbapenem-resistant Enterobacterales (CA-CRE) are an important threat. Methods: In CRACKLE-2, we defined patients with CA-CRE as admitted from home, without pre-existing conditions, and a positive culture within 48 h of admission. Healthcare-Associated CRE (HA-CRE) were those with the lowest likelihood of community acquisition, not admitted from home and cultured >48 h after admission. Specific genetic markers in carbapenemase-producing Klebsiella pneumoniae were evaluated through random forest modelling. Results: CA-CRE and HA-CRE were detected in 83 (10%) and 208 (26%) of 807 patients. No significant differences were observed in bacterial species or strain type distribution. K. pneumoniae (204/291, 70%) was the most common CRE species, of these 184/204 (90%) were carbapenemase producers (CPKP). The top three genetic markers in random forest models were kpi_SA15, fimE, and kpfC. Of these, kpi_SA15 (which encodes a chaperone/usher system) was positively associated (OR 3.14, 95% CI 1.13-8.87, P = 0.026), and kpfC negatively associated (OR 0.21, 95% CI 0.05-0.72, P = 0.015) with CA-CPKP. Conclusions: Ten percent of CDC-defined CRE were CA. The true proportion of CA-CRE in hospitalized patients is likely lower as patients may have had unrecorded prior healthcare exposure. The kpi_SA15 operon was associated with the CA phenotype

Retreatment of hepatitis C non-responsive to Interferon. A placebo controlled randomized trial of Ribavirin monotherapy versus combination therapy with Ribavirin and Interferon in 121 patients in the Benelux [ISRCTN53821378]

BACKGROUND: Evidence based medicine depends on unbiased selection of completed randomized controlled trials. For completeness it is important to publish all trials. This report describes the first large randomised controlled trial where combination therapy was compared to placebo therapy and to ribavirin monotherapy, which has not been published untill now. METHODS: One hundred and twenty one patients with chronic hepatitis C and elevated transaminases who did not respond to previous treatment with standard interferon monotherapy, were included from 16 centers in Belgium, the Netherlands and Luxembourg between 1992 and 1996. Patient poor-response characteristics were: genotype 1 (69%), HCV RNA above 2 × 10(6 )copies/ml (55%) and cirrhosis (38%). Patients were randomized to 6 months combination therapy with interferon alpha-2b (3 MU tiw) and ribavirin (1000–1200 mg / day), 6 months ribavirin monotherapy (1000–1200 mg / day) or 6 months ribavirin placebo. The study was double blinded for the ribavirin / placebo component. One patient did not fit the entry criteria, and 3 did not start. All 117 patients who received at least one dose of treatment were included in the intention to treat analysis. RESULTS: At the end of treatment, HCV RNA was undetectable in 35% of patients on combination therapy and in none of the patients treated with ribavirin monotherapy or placebo. The sustained virological response rate at 6 months after therapy was 15% for patients treated with interferon and ribavirin. During the 6 months treatment period 13% of patients on interferon ribavirin combination therapy, 13% of patients on ribavirin monotherapy and 11% of patients on placebo withdrew due to side effects or noncompliance. At 24 weeks of treatment the mean Hb level was 85% of the baseline value, which means a mean decrease from 9.1 mmol/l to 7.8 mmol/l. The Hb levels at the end of treatment were not significantly different from patients treated with ribavirin monotherapy (p = 0.76). End of treatment WBC was significantly lower in patients treated with combination therapy, compared to ribavirin (p < 0.01) as well as for patients treated with ribavirin monotherapy compared to placebo (p < 0.01). DISCUSSION: This belated report on the only placebo controlled study of interferon ribavirin combination therapy in non responders to standard doses of interferon monotherapy documents the effectiveness, be it limited, of this approach as well as the dynamics of the effects on blood counts

Carbapenem-Resistant Acinetobacter baumannii in U.S. Hospitals: Diversification of Circulating Lineages and Antimicrobial Resistance

Carbapenem-resistant Acinetobacter baumannii (CRAb) is a major cause of health care-associated infections. CRAb is typically multidrug resistant, and infection is difficult to treat. Despite the urgent threat that CRAb poses, few systematic studies of CRAb clinical and molecular epidemiology have been conducted. The Study Network of Acinetobacter as a Carbapenem-Resistant Pathogen (SNAP) is designed to investigate the clinical characteristics and contemporary population structure of CRAb circulating in U.S. hospital systems using whole-genome sequencing (WGS). Analysis of the initial 120 SNAP patients from four U.S. centers revealed that CRAb remains a significant threat to hospitalized patients, affecting the most vulnerable patients and resulting in 24% all-cause 30-day mortality. The majority of currently circulating isolates belonged to ST2Pas, a part of clonal complex 2 (CC2), which is the dominant drug-resistant lineage in the United States and Europe. We identified three distinct sublineages within CC2, which differed in their antibiotic resistance phenotypes and geographic distribution. Most concerning, colistin resistance (38%) and cefiderocol resistance (10%) were common within CC2 sublineage C (CC2C), where the majority of isolates belonged to ST2Pas/ST281Ox. Additionally, we identified ST499Pas as the most common non-CC2 lineage in our study. Our findings suggest a shift within the CRAb population in the United States during the past 10 years and emphasize the importance of real-time surveillance and molecular epidemiology in studying CRAb dissemination and clinical impact

The structure of the Yang-Mills spectrum for arbitrary simple gauge algebras

The mass spectrum of pure Yang-Mills theory in 3+1 dimensions is discussed for an arbitrary simple gauge algebra within a quasigluon picture. The general structure of the low-lying gluelump and two-quasigluon glueball spectrum is shown to be common to all algebras, while the lightest $C=-$ three-quasigluon glueballs only exist when the gauge algebra is A$_{r\geq 2}$, that is in particular $\mathfrak{su}(N\geq3)$. Higher-lying $C=-$ glueballs are shown to exist only for the A$_{r\geq2}$, D$_{{\rm odd}-r\geq 4}$ and E$_6$ gauge algebras. The shape of the static energy between adjoint sources is also discussed assuming the Casimir scaling hypothesis and a funnel form; it appears to be gauge-algebra dependent when at least three sources are considered. As a main result, the present framework's predictions are shown to be consistent with available lattice data in the particular case of an $\mathfrak{su}(N)$ gauge algebra within 't Hooft's large-$N$ limit.Comment: 21 pages, 4 figures; remarks added, typos corrected in v2. v3 to appear in EPJ

Biomarkers of exposure to new and emerging tobacco delivery products

Accurate and reliable measurements of exposure to tobacco products are essential for identifying and confirming patterns of tobacco product use and for assessing their potential biological effects in both human populations and experimental systems. Due to the introduction of new tobaccoderived products and the development of novel ways to modify and use conventional tobacco products, precise and specific assessments of exposure to tobacco are now more important than ever. Biomarkers that were developed and validated to measure exposure to cigarettes are being evaluated to assess their use for measuring exposure to these new products. Here, we review current methods for measuring exposure to new and emerging tobacco products, such as electronic cigarettes, little cigars, water pipes, and cigarillos. Rigorously validated biomarkers specific to these new products have not yet been identified. Here, we discuss the strengths and limitations of current approaches, including whether they provide reliable exposure estimates for new and emerging products. We provide specific guidance for choosing practical and economical biomarkers for different study designs and experimental conditions. Our goal is to help both new and experienced investigators measure exposure to tobacco products accurately and avoid common experimental errors. With the identification of the capacity gaps in biomarker research on new and emerging tobacco products, we hope to provide researchers, policymakers, and funding agencies with a clear action plan for conducting and promoting research on the patterns of use and health effects of these products