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The versatile structure of smectites can exhibit large variations in chemical compositions and cationic substitutions in different crystallographic sites, resulting in various locations of layer charge. Natural smectites can contain various amounts of structural iron, the chemical form of which can influence the reactivity of these minerals. The variety of Fe crystal chemistry in smectite was explored for eight natural smectites of distinct chemical compositions and charge locations, together with two synthetic ferric saponites used as reference compounds for tetrahedral Fe(III). All samples were identified as dioctahedral or trioctahedral smectite by X-ray diffraction and Fourier-transform infrared spectroscopy. The extent of [4]Al for [4]Si substitution was determined by 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy. The Fe local chemical environment was probed by polarized X-ray absorption spectroscopy. Only Fe(III) could be detected in all samples, with no evidence of cluster formation. The O shell at 1.86 Å in synthetic saponites suggests Fe insertion in tetrahedral sites, and the absence of detected octahedral Fe implies quantitative substitution of [4]Fe3+ for [4]Si4+. In natural smectites, Fe(III) is bound to six O atoms at ~ 2.00 Å, suggesting insertion in octahedral sites. This inference is also supported by the detection of in-plane Mg/Al/Fe atoms at ~ 3.05 Å and out-of-plane Si/Al atoms at ~ 3.25 Å. In one Fe-rich nontronite, the detection of an O subshell at ~ 1.88 Å suggests a concomitant insertion of Fe(III) in tetrahedral sites. Low numbers of octahedral neighbors were detected in natural saponite and hectorite, presumably because of the presence of vacancies and/or Li(I) in adjacent octahedral sites balancing the local charge excess originating from the substitution of Fe(III) for Mg(II). The substitution of [4]Fe3+ for [4]Si4+ can be readily obtained under defined conditions in the laboratory, but seems more rare in natural samples, or present in amounts below the detection limit of spectroscopic methods used in this study. [ABSTRACT FROM AUTHOR]

The chemical form of structural Fe in smectites influences many physicochemical properties of these clay minerals. Powder EXAFS data for structural Fe in smectites have been reported; however, the preferred orientation of clay platelets with respect to the X-ray beam may lead to erroneous conclusions on the local chemical environment. Dioctahedral montmorillonite and for the first time trioctahedral hectorite were prepared as textured samples, and the Fe local environment was probed by analysis of the X-ray absorption pre-edge peaks at the magic angle and by polarized EXAFS (P-EXAFS) spectroscopy. Compared to powder measurements, overlapping contributions from shells with distinct orientations can be filtered more easily by P-EXAFS, thus decreasing uncertainties on structural parameters. The pre-edge spectrum of montmorillonite is similar to spectra commonly reported for dioctahedral smectites. In contrast, the pre-edge spectrum of hectorite is notably distinct and hints to either differences in the site symmetry and/or in covalence. In both smectites, Fe is surrounded by a first O shell at a distance consistent with sixfold-coordinated Fe(III), suggesting that Fe(III) is located in the smectite octahedral sheet. This is corroborated by the distances and orientations of neighboring cationic shells, such as in-plane (Mg, Al) and out-of-plane Si shells. For montmorillonite, the results indicate Fe substitution for Al/Mg in the octahedral sheet, and a number of Fe neighbors consistent with random distribution in the octahedral sheet. For hectorite, results indicate a slight tendency for Fe atoms to form pairs in octahedral sheets; however, low numbers of neighboring cations were obtained, presumably a consequence of the presence of vacancies and/or Li in the vicinity of Fe, or of the coexistence of Fe and Mg neighbors with mutually canceling EXAFS waves. Consistent with pre-edge data, the coordination numbers can also indicate some incoherency in Fe-cation interatomic distances in hectorite as a consequence of site distortion. These results suggest that Fe in hectorite locally distorts the structure of the trioctahedral phyllosilicate and tends to aggregate charge-deficient (i.e., vacant or Li-containing) octahedral sites. [ABSTRACT FROM AUTHOR]

We report the epidemiological and clinical features of the first outbreak of Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-KP) type 2 in Switzerland. The outbreak took place in the medical intensive care unit (MICU) of our tertiary care hospital and affected three severely ill patients. After the implementation of strict infection control measures, no further patients colonised with KPC-KP could be detected by the screening of exposed patients. Successful treatment of patients infected with KPC-KP consisted of a combination therapy of meropenem, colistin and tigecycline. [ABSTRACT FROM AUTHOR]

Purpose: Methicillin-resistant Staphylococcus aureus (MRSA) decolonization is a widely established, though controversial part of many MRSA controlling strategies. The aim of this study was to evaluate our decolonization success rate, identify the risk factors for decolonization failure and determine the optimal duration of follow-up in our low MRSA prevalence setting (2.6 % of isolates). Methods: Every patient with newly detected MRSA colonization or infection between January 2007 and December 2009 was recruited to the study. The MRSA strategy of our institution (a 700 bed tertiary hospital in eastern Switzerland) consists of a 5-day regimen of nasal mupirocin ointment, chlorhexidin mouth rinse and whole body wash with didecyldimonium chloride. Systemic antibiotics are usually not added to the regimen. Results: We determined a MRSA decolonization success rate of 65 % (33/51) after a median follow-up of 13 months [i.e. a tripling of the spontaneous clearance rate of 22 % (6/27) in the non-decolonized group]. The most important risk factor for decolonization failure was colonization of the respiratory tract [odds risk (OR) 9.1, 95 % confidence interval (CI) 1.2-66.7], as well as isolation of MRSA spa-type 002 ([R 5.8, 95 % CI 1.0-33.3). Of all the episodes of MRSA recurrence, 88 % (14/16) were detected within 270 days after decolonization. Conclusion: High MRSA decolonization success rates can be achieved without the routine use of oral antibiotics. A time period of 1 year after decolonization seems to be a reasonable duration of follow-up in our setting. We encourage other institutions to take into account local MRSA epidemiology (e.g. predominance of certain subtypes) for the management of MRSA patients. [ABSTRACT FROM AUTHOR]

Catheter-related bloodstream infections (CRBSI) are a leading cause of nosocomial infections associated with significant mortality and costs. The objective of this study was to determine the rate of CRBSI in two large Swiss hospitals and to identify risk factors for this condition. During 1 year all central venous catheter (CVC)-inserted in patients admitted for visceral, orthopedic or urologic surgery at the cantonal hospital in St Gallen and cantonal hospital in Chur were included in the study. Catheters were followed for the duration of their insertion. Blood cultures and semiquantitative cultures from catheters were drawn in the presence of local or systemic signs of infection. Primary endpoint was CRBSI defined as definite if (a) the same pathogen grew in at least one blood culture and from the distal segment of the catheter or (b) the same pathogen grew in at least one peripherally and centrally drawn blood culture and the differential time to positivity of central blood culture vs peripheral blood culture was > 120 min. CRBSI was defined as probable if at least one blood culture was positive with a recognized pathogen in the absence of another site of infection. Data were analyzed using univariate and multivariate time-to-event methods. During the study period, 1,396 CVCs were prospectively studied in 1,162 patients. Incidence density of all CRBSIs (definite n = 29, probable n = 7) was 2.5 (95% CI: 1.8–3.5) per 1,000 catheter-days. The lowest rate of CRBSI was found in subclavian catheters, the adjusted hazard ratio (HR) for jugular catheters was 2.2 (95% CI: 1.1– 4.3; p = 0.03) and for femoral catheters 2.9 (95% CI: 0.6– 14.4; p = 0.19). Each additional lumen increased the risk (HR = 4.4; 95% CI: 2.5–7.7; p < 0.001), whereas the permanent blocking of additional lumens was protective (HR = 0.3; 95% CI: 0.1–0.7; p = 0.006). The most commonly isolated organism were coagulase-negative staphylococci with a rate of 28%. Number of lumens and site of access were independent risk factors for CRBSI. The use of catheters with multiple lumens should therefore be restricted as far as possible. If a catheter cannot be removed, the permanent closure of unneeded lumens may reduce the risk of CRBSI. [ABSTRACT FROM AUTHOR]

The single-spin asymmetries for a longitudinally polarized lepton beam or a longitudinally polarized nucleon target in semi-inclusive deep-inelastic scattering are twist-3 observables. We study these asymmetries in a simple diquark spectator model of the nucleon. Analogous to the case of transverse target polarization, non-vanishing asymmetries are generated by gluon exchange between the struck quark and the target system. It is pointed out that the coupling of the virtual photon to the diquark is needed in order to preserve electromagnetic gauge invariance at the twist-3 level. The calculation indicates that previous analyses of these observables are incomplete. [ABSTRACT FROM AUTHOR]

Application of polarized extended X-ray absorption fine structure (P-EXAFS) spectroscopy to thin films of fine-grained minerals is emerging as a powerful method to investigate the in-plane and out-of-plane local structure of phyllosilicates. Mineral platelets have no preferential orientation in the plane of the film, and their c* axes are oriented essentially along the film normal. The angular dependence of the EXAFS amplitude critically depends on the orientation distribution of c* axes due to mosaic spread. The effect of film texture on EXAFS amplitude has been calculated as a function of the mosaic spread, the orientation of the electric field vector, and the crystallographic orientation of the atomic pair. Calculations show that the reduction in amplitude for partially ordered films is more important when the electric field vector is perpendicular to the film plane. For phyllosilicates, no significant deviation from single crystal dichroism occurs when the mosaic spread is less than ±20–25° half-width at half-maximum (HWHM) for parallel measurement, and ±15–20° HWHM for normal measurement. Graphs are given for correcting EXAFS-derived coordination numbers for texture effects. [ABSTRACT FROM AUTHOR]

The small subunit ribosomal RNA (16S-like rRNA) coding regions of the hypotrichous ciliates Onychodromus quadricornutus and Oxytricha granulifera were amplified using polymerase chain reaction techniques. Complete sequences were determined for the amplified genes and compared to those of other ciliated protozoa. In phylogenetic trees inferred using distance matrix methods oxytrichids are not seen as a cohesive phylogenetic group. Oxytricha nova is most closely related to Stylonychia pustulata in a lineage that also includes O. quadricornutus. This phylogeny contradicts phylogenetic schemes in which Onychodromus is considered to be a primitive hypotrichous ciliate and suggests that O. nova was misidentified as members of the genus Oxytricha. [ABSTRACT FROM AUTHOR]

The chromatin fraction of transcriptionally active macronuclei of Stylonychia lemnae shows a typical core histone pattern after SDS-polyacrylamide gel electrophoresis (SDS-PAGE). However, extracts of transcriptionally inactive micronuclei display only two bands in the molecular weight range of macronuclear core histones, corresponding to macronuclear H2A/H2B and H4. While a band corresponding to macronuclear H3 cannot be detected, the micronuclear fraction contains a prominent Mr 21,000 protein (protein X). We examined the chromatin fractions of the two kinds of nuclei in detail using specific antibodies directed against core histones and synthetic peptides of histones. Both microand macronuclei contain histones that are specifically recognized by antibodies directed against H2A, H2B and H4. Antigenicity in association with core histone H3 is found only in the macronuclear anlagen and in macronuclear extracts. None of the antibodies used react with the micronucleus specific protein X. During macronuclear development protein X disappears while macronuclear H3 appears. Thus we speculate, that protein X may be functionally related to macronuclear H3. The inactive state of the micronucleus is also characterized by the presence of two proteins, Y and Y, with apparent Mrs of 45,000 in SDS-polyacrylamide gels. These proteins are recognized by antibodies raised against the N-terminal peptide of H3 and the C-terminal peptide of H2B respectively. Y and Y are also present during all of the transcriptionally inactive stages of macronuclear development but are not found in the active macronucleus. By these means chromatin extracts of micronuclei, macronuclear anlagen and macronuclei can be clearly distinguished. The observed differences reveal a sequence of changes in chromatin organization that correlate with the transition from the transcriptionally inactive to the transcriptionally active state of the chromatin. [ABSTRACT FROM AUTHOR]

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Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)