Compositional tuning of gas-phase synthesized Pd-Cu nanoparticles.

Bimetallic nanoparticles have gained significant attention in catalysis as potential alternatives to expensive catalysts based on noble metals. In this study, we investigate the compositional tuning of Pd-Cu bimetallic nanoparticles using a physical synthesis method called spark ablation. By utilizing pure and alloyed electrodes in different configurations, we demonstrate the ability to tailor the chemical composition of nanoparticles within the range of approximately 80 : 20 at% to 40 : 60 at% (Pd : Cu), measured using X-ray fluorescence (XRF) and transmission electron microscopy energy dispersive X-ray spectroscopy (TEM-EDXS). Time-resolved XRF measurements revealed a shift in composition throughout the ablation process, potentially influenced by material transfer between electrodes. Powder X-ray diffraction confirmed the predominantly fcc phase of the nanoparticles while high-resolution TEM and scanning TEM-EDXS confirmed the mixing of Pd and Cu within individual nanoparticles. X-ray photoelectron and absorption spectroscopy were used to analyze the outermost atomic layers of the nanoparticles, which is highly important for catalytic applications. Such comprehensive analyses offer insights into the formation and structure of bimetallic nanoparticles and pave the way for the development of efficient and affordable catalysts for various applications.

Towards Preventing Gaps in Health Care Systems through Smartphone Use: Analysis of ARKit for Accurate Measurement of Facial Distances in Different Angles.

There is a growing consensus in the global health community that the use of communication technologies will be an essential factor in ensuring universal health coverage of the world's population. New technologies can only be used profitably if their accuracy is sufficient. Therefore, we explore the feasibility of using Apple's ARKit technology to accurately measure the distance from the user's eye to their smartphone screen. We developed an iOS application for measuring eyes-to-phone distances in various angles, using the built-in front-facing-camera and TrueDepth sensor. The actual position of the phone is precisely controlled and recorded, by fixing the head position and placing the phone in a robotic arm. Our results indicate that ARKit is capable of producing accurate measurements, with overall errors ranging between 0.88% and 9.07% from the actual distance, across various head positions. The accuracy of ARKit may be impacted by several factors such as head size, position, device model, and temperature. Our findings suggest that ARKit is a useful tool in the development of applications aimed at preventing eye damage caused by smartphone use.

Mo3Ni2N Nanoparticle Generation by Spark Discharge.

Spark ablation is an advantageous method for the generation of metallic nanoparticles with defined particle sizes and compositions. The reaction of the metal particles with the carrier gas during the synthesis and, therefore, the incorporation of those light elements into structural voids or even compound formation was confirmed for hydrides and oxides but has only been suspected to occur for nitrides. In this study, dispersed nanoparticles of Mo3Ni2N and Mo with Janus morphology, and defined particle sizes were obtained by spark discharge generation as a result of carrier gas ionization and characterized using transmission electron microscopy and powder X-ray diffraction. Metal nitrides possess beneficial catalytic and thermoelectric properties, as well as high hardness and wear resistance. Therefore, this method offers the possibility of controlled synthesis of materials which are interesting for numerous applications.

New Insights into the Crystal Chemistry of FeB-Type Compounds: The Case of CeGe.

Several alkaline earth or rare earth binary monosilicides and -germanides possess complex bonding properties, such as polycation formation exceeding the scope of classical electron counting rules. In this study, we present characterization by powder and single-crystal diffraction and thermal analysis of CeGe, one of the few monogermanides crystallizing in the FeB-type structure. Comparative computational investigations for structure types experimentally observed for monogermanides and alternative structures with different structural motifs were performed to gain energetical insights into this family of compounds, underlining the preference for infinite germanium chains over other structural motifs. Formation enthalpy calculations and structural chemical analysis highlight the special position of FeB-type compounds among the monogermanides.

Temporary Cohabitation: The Metastable Phase Au4Si.

The prediction, identification, and characterization of phases away from equilibrium conditions remain difficult challenges for material science. Herein, we demonstrate how systems whose phase diagrams contain deeply incising eutectics can offer opportunities to address these challenges. We report the synthesis of a new compound in the Au-Si system, a textbook example of a system with a deep eutectic. Au4Si crystallizes in a complex √18×√2×1 superstructure of the PtHg4 type, based on the distortion of vertex-sharing Si@Au8 cubes into bisdisphenoids. Au4Si decomposes upon heating and at room temperature even in high vacuum, highlighting its metastability. Electronic structure analysis reveals a pseudogap at the Fermi energy, which is enhanced by the superstructure through the relief of Au-Au antibonding interactions. The pseudogap is associated with a Zintl-type bonding scheme, which can be extended to the locally ordered liquid. These results highlight the potential for metastable phases to form in deep eutectics that preserve the local structures of the liquid.

A Borosilicide with Clathrate VIII Structure.

The high-pressure phase Na8BxSi46-x (3 < x < 5) is the first representative of a borosilicide crystallizing in the rarely occurring clathrate VIII type structure. Crystals with composition Na8B4Si42 (space group I43̅m; a = 9.7187(2) Å; Pearson symbol cI54) were obtained at 5-8 GPa and 1200 K. The clathrate I modification exists for the same composition at lower pressure with a larger cell volume (Pm3̅n; a = 9. 977(2) Å; cP54). Profound structural adaptions allow for a higher density of the clathrate VIII type than clathrate I, opening up the perspective of obtaining clathrate VIII type compounds as high-pressure forms of clathrate I.

The impact of boron atoms on clathrate-I silicides: composition range of the borosilicide K8-xBySi46-y.

The clathrate-I borosilicide K8-xBySi46-y (0.8 ≤x≤ 1.2 and 6.4 ≤y≤ 7.2; space group Pm3[combining macron]n) was prepared in sealed tantalum ampoules between 900 °C and 1000 °C. By high-pressure preparation at 8 GPa and 1000 °C, a higher boron content is achieved (x = 0.2, y = 7.8). Crystal structure and composition were established from X-ray diffraction data, chemical analysis, WDX spectroscopy, and confirmed by 11B and 29Si NMR, and magnetic susceptibility measurements. The compositions are electron-balanced according to the Zintl rule within one estimated standard deviation. The lattice parameter varies with composition from a = 9.905 Å for K7.85(2)B7.8(1)Si38.2(1) to a = 9.968(1) Å for K6.80(2)B6.4(5)Si39.6(5).

Cage Adaption by High-Pressure Synthesis: The Clathrate-I Borosilicide Rb8B8Si38.

Rb8B8Si38 forms under high-pressure, high-temperature conditions at p = 8 GPa and T = 1273 K. The new compound (space group Pm3̅n, a = 9.9583(1) Å) is the second example for a clathrate-I borosilicide. The phase is inert against strong acids and bases and thermally stable up to 1300 K at ambient pressure. (Rb+)8(B-)8(Si0)38 is electronically balanced, diamagnetic, and shows semiconducting behavior with moderate Seebeck coefficient below 300 K. Chemical bonding analysis by the electron localizability approach confirms the description of Rb8B8Si38 as Zintl phase.

"Excess" electrons in LuGe.

The monogermanide LuGe is obtained via high-pressure high-temperature synthesis (5-15 GPa, 1023-1423 K). The crystal structure is solved from single-crystal X-ray diffraction data (structure type FeB, space group Pnma, a=7.660(2) Å, b=3.875(1) Å, and c=5.715(2) Å, RF =0.036 for 206 symmetry independent reflections). The analysis of chemical bonding applying quantum-chemical techniques in position space was performed. It revealed-beside the expected 2c-Ge-Ge bonds in the germanium polyanion-rather unexpected four-atomic bonds between lutetium atoms indicating the formation of a polycation by the excess electrons in the system Lu3+ (2b)Ge2- ×1 e- . Despite the reduced VEC of 3.5, lutetium monogermanide is following the extended 8-N rule with the trend to form lutetium-lutetium bonds utilizing the electrons left after satisfying the bonding needs in the anionic Ge-Ge zigzag chain.

In-Cage Interactions in the Clathrate Superconductor Sr8 Si46.

The clathrate I superconductor Sr8 Si46 is obtained under high-pressure high-temperature conditions, at 5 GPa and temperatures in the range of 1273 to 1373 K. At ambient pressure, the compound decomposes upon heating at T=796(5) K into Si and SrSi2 . The crystal structure of the clathrate is isotypic to that of Na8 Si46 . Chemical bonding analysis reveals conventional covalent bonding within the silicon network as well as additional multi-atomic interactions between Sr and Si within the framework cages. Physical measurements indicate a bulk BCS type II superconducting state below Tc =3.8(3) K.

Unconventional Metal-Framework Interaction in MgSi5.

The silicon-rich cage compound MgSi5 was obtained by high-pressure high-temperature synthesis. Initial crystal structure determination by electron diffraction tomography provided the basis for phase analyses in the process of synthesis optimization, finally facilitating the growth of single crystals suitable for X-ray diffraction experiments. The crystal structure of MgSi5 (space group Cmme, Pearson notation oS24, a=4.4868(2) Å, b=10.1066(5) Å, and c=9.0753(4) Å) constitutes a new type of framework of four-bonded silicon atoms forming Si15 cages enclosing the Mg atoms. Two types of smaller Si8 cages remain empty. The atomic interactions are characterized by two-center two-electron bonds within the silicon framework. In addition, there is evidence for multi-center Mg-Si bonding in the large cavities of the framework and for lone-pair-like interactions in the smaller empty voids.

High-Pressure Synthesis and Chemical Bonding of Barium Trisilicide BaSi3.

BaSi3 is obtained at pressures between 12(2) and 15(2) GPa and temperatures from 800(80) and 1050(105) K applied for one to five hours before quenching. The new trisilicide crystallizes in the space group I 4 ¯ 2m (no. 121) and adopts a unique atomic arrangement which is a distorted variant of the CaGe3 type. At ambient pressure and 570(5) K, the compound decomposes in an exothermal reaction into (hP3)BaSi2 and two amorphous silicon-rich phases. Chemical bonding analysis reveals covalent bonding in the silicon partial structure and polar multicenter interactions between the silicon layers and the barium atoms. The temperature dependence of electrical resistivity and magnetic susceptibility measurements indicate metallic behavior.

Lutetium Trigermanide LuGe3: High-Pressure Synthesis, Superconductivity, and Chemical Bonding.

LuGe3 was obtained under high-pressure and high-temperature conditions at pressures between 8(1) and 14(2) GPa and at temperatures in the range from 1100(150) to 1500(150) K. The high-pressure phase is isotypic to DyGe3 and decomposes at ambient pressure and T = 690 K mainly into ( cF8)Ge and LuGe2- x. Chemical bonding analysis of LuGe3 reveals two-center electron-deficient Ge-Ge bonds, multicenter polar Lu-Ge interactions, and lone pairs on germanium. Magnetic susceptibility, specific heat, and electrical conductivity measurements indicate transition into a superconducting state below Tc = 3.3(3) K.

Filifactor alocis--involvement in periodontal biofilms.

BACKGROUND: Bacteria in periodontal pockets develop complex sessile communities that attach to the tooth surface. These highly dynamic microfloral environments challenge both clinicians and researchers alike. The exploration of structural organisation and bacterial interactions within these biofilms is critically important for a thorough understanding of periodontal disease. In recent years, Filifactor alocis, a fastidious, Gram-positive, obligately anaerobic rod was repeatedly identified in periodontal lesions using DNA-based methods. It has been suggested to be a marker for periodontal deterioration. The present study investigated the epidemiology of F. alocis in periodontal pockets and analysed the spatial arrangement and architectural role of the organism in in vivo grown subgingival biofilms. RESULTS: A species-specific oligonucleotide probe, FIAL, was designed and evaluated. A total of 490 subgingival plaque samples were submitted to PCR and subsequent dot blot hybridization to compare the prevalence of F. alocis in patients suffering from generalized aggressive periodontitis (GAP), chronic periodontitis (CP), and control subjects resistant to periodontitis. Moreover, a specially designed carrier system was used to collect in vivo grown subgingival biofilms from GAP patients. Subsequent topographic analysis was performed using fluorescence in situ hybridization.While the majority of patients suffering from GAP or CP harboured F. alocis, it was rarely detected in the control group. In the examined carrier-borne biofilms the organism predominantly colonized apical parts of the pocket in close proximity to the soft tissues and was involved in numerous structures that constitute characteristic architectural features of subgingival periodontal biofilms. CONCLUSIONS: F. alocis is likely to make a relevant contribution to the pathogenetic structure of biofilms accounting for periodontal inflammation and can be considered an excellent marker organism for periodontal disease.

Involvement of Guggenheimella bovis in digital dermatitis lesions of dairy cows.

Digital dermatitis (DD) of cattle leads to lameness and a decrease of milk production and is responsible for major economic losses worldwide. Although a bacterial aetiology is generally accepted, it still is unclear which microorganisms cause and/or maintain the disease. Recently, a previously undiscovered bacterial species, Guggenheimella bovis, has been isolated from the front of two DD lesions in Swiss cattle and suggested as a potential pathogen. The aims of the present study were to determine the prevalence of G. bovis in 58 German cows suffering from DD via dot blot hybridization, and to analyse the spatial distribution of G. bovis within the affected tissue by fluorescence in situ hybridization (FISH). A species-specific probe, GUBO1, was designed and evaluated. In none of the 58 samples Guggenheimella could be detected, while cultured G. bovis was reliably identified by GUBO1. Further FISH experiments were carried out on two additional biopsies of Swiss cattle tested positive for G. bovis by quantitative PCR and permitted visualization of the newly discovered bacteria in situ. In these biopsies G. bovis proved to be tissue invasive forming characteristic spherical microcolonies not only within the bacterial biofilm but also in seemingly unaffected parts of the tissue not yet reached by the advancing bacterial front. Although the presence of G. bovis does not constitute an essential premise for DD, it seems likely that the bacterial species involved in DD vary, and that in some cases G. bovis is crucial for the development of DD lesions.

[Prescribing practices in the treatment of upper respiratory tract infections in anthroposophic medicine]. / Verordnungsverhalten anthroposophisch orientierter ärzte bei akuten Infektionen der oberen Atemwege.

BACKGROUND: Upper respiratory tract infections (URTI) are among the leading reasons for doctor consultations. This study investigates the prescribing practices of medical doctors specialized in anthroposophic medicine in the treatment of URTI with a special focus on the prescription of antibiotics, complications, recurrence rates and costs. MATERIALS AND METHODS: Starting in May 2004 all prescriptions within a 1-year period by 35 primary care practitioners in Germany were analysed. Data were extracted from practice software with special interfaces with additional linking of medications and diagnoses by practitioners. RESULTS: 21,818 prescriptions for 12,081 patients (73.7%children) with 19,050 cases of URTI were analysed. The most common diagnosis was common cold (63.3%), followed by acute tonsillitis (12.9%). 63.0% were treated purely with complementary medicine. Antibiotics were given in 6.3% of cases (minimum: common cold 1.9%, maximum: tonsillitis 24.3%). Predictive factors for antibiotic prescribing were the diagnoses tonsillitis (odds ratio [OR]: 6.7; 95% confidence interval [CI]:4.5-9.9) and sinusitis (OR: 1.9; 95% CI: 1.1-3.1), concomitant disease (OR: 1.2; 95% CI: 1.0-1.4), complications (OR: 7.2; 95% CI:5.5-9.4) and the specialty paediatrics (OR: 2.1; 95% CI: 1.7-2.6). In cases that were initially treated with only complementary medicine, antibiotics were eventually prescribed in 0.7%. Overall complication rates were 2.9% and follow-up visits occurred in 6.3%. Patients had an average of 2.4 URTI/year (adults 1.7,children 2.7). Treatment costs did not differ between complementary care and antibiotics. CONCLUSION: Prescription practices in the treatment of URTI by anthroposophic practitioners were documented through the processing of routine medical data with minimal additional data. The therapy was found to be in accordance with the guidelines, however, the prescription rate for antibiotics was well below the German average.