Publications by authors named "Helm M"

A nickel bis(diphosphine) complex containing proton relays in the second and outer coordination spheres, Ni(P(Cy)2N((CH2)2OMe))2, (P(Cy)2N((CH2)2OMe) = 1,5-di(methoxyethyl)-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane), is an electrocatalyst for hydrogen oxidation. The addition of hydrogen to the Ni(II) complex results in rapid formation of three isomers of the doubly protonated Ni(0) complex, [Ni(P(Cy)2N((CH2)2OMe)2H)2](2+). The three isomers show fast interconversion at 40 °C, unique to this complex in this class of catalysts.

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The general approach to the initial resuscitation of non-trauma patients does not differ from the ABCDE approach used to evaluate severely injured patients. After initial stabilization of vital functions patients are evaluated based on the symptoms and critical care interventions are initiated as and when necessary. Adequate structural logistics and personnel organization are crucial for the treatment of non-trauma critically ill patients although there is currently a lack of clearly defined requirements.

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Skin metastases are rare in the routine clinical practice of dermatology, but are of major clinical significance because they usually indicate advanced disease. We reviewed the literature on skin metastasis regarding recent trends in clinical presentation and diagnosis of the most common cutaneous lesions. An extensive literature review was conducted using PubMed from May 26, 2011 to July 16, 2013 relating cutaneous metastases.

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A controlled shunting of polycrystalline oxide thin films on the nanometer length scale opens the door to significantly modify their transport properties. In this paper, the low energy Ar(+) irradiation induced shunting effect of forming-free, non-volatile resistive switching in polycrystalline BiFeO3 thin film capacitor-like structures with macroscopic bottom and top contacts was investigated. Oxygen atoms at the BiFeO3 surface are preferentially sputtered by Ar(+) ion irradiation and oxygen vacancies and a metallic Bi phase are formed at the surface of the BiFeO3 thin film before deposition of the top contacts.

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Background: In emergency medicine intraosseous access (IOA) has been established as an alternative to conventional intravenous access. Originally the use of IOA was strictly limited to children up to 6 years of age and to adults for cardiopulmonary resuscitation. These limitations have been relaxed and the indications for IOA have been expanded.

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Background: Trauma is the leading cause of death in the patient group under 40 years of age. Within the prehospital management of seriously injured trauma victims the accuracy of the field triage by emergency physicians is of utmost importance.

Objective: The aim of this study was to determine the accuracy of prehospital emergency physician field triage in road traffic accident victims.

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Canine leishmaniosis (CL) has become one of the most frequently diagnosed travel associated infection in dogs in Switzerland and Germany. The aim of the study was to define recommendations for treatment with allopurinol and follow-up examinations of dogs with CL in a non endemic area. 31 dogs infected with Leishmania were treated with allopurinol (10 - 15 mg/kg twice daily, per os) and the effectiveness was examined.

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High-quality chest compressions are crucial during resuscitation if a positive outcome is to be achieved. Sometimes a patient must be transported within the hospital while chest compressions are being performed. We compared different chest compression devices [animax mono (AM), AutoPulse(®) (AP) and LUCAS2™ (L2)] with manual chest compression using a manikin during transport from a fifth floor ward to the cardiac catheterization laboratory in the basement.

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A significant number of proteins in both eukaryotes and prokaryotes are known to be post-translationally modified by the addition of phosphate, serving as a means of rapidly regulating protein function. Phosphorylation of the amino acids serine, threonine and tyrosine are the focus of the vast majority of studies aimed at elucidating the extent and roles of such modification, yet other amino acids, including histidine and aspartate, are also phosphorylated. Although histidine phosphorylation is known to play extensive roles in signalling in eukaryotes, plants and fungi, roles for phosphohistidine are poorly defined in higher eukaryotes.

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Normal incidence ion irradiation at elevated temperatures, when amorphization is prevented, induces novel nanoscale patterns of crystalline structures on elemental semiconductors by a reverse epitaxial growth mechanism: on Ge surfaces irradiation at temperatures above the recrystallization temperature of 250 °C leads to self-organized patterns of inverse pyramids. Checkerboard patterns with fourfold symmetry evolve on the Ge (100) surface, whereas on the Ge (111) surface, isotropic patterns with a sixfold symmetry emerge. After high-fluence irradiations, these patterns exhibit well-developed facets.

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This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures. Polycrystalline BiFeO3 thin films are deposited by pulsed laser deposition at different temperatures on Pt/Ti/SiO2/Si substrates. From the energy filtered transmission electron microscopy and Rutherford backscattering spectrometry it is observed that Ti diffusion occurs if the deposition temperature is above 600°C.

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Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2Δ/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2Δ/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.

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Selective alkylation of RNA nucleotides is an important field of RNA biochemistry, e.g. in applications of fluorescent labeling or in structural probing experiments, yet detailed structure-function studies of labeling agents are rare.

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We report a synthetic nickel complex containing proton relays, [Ni(P(Ph)2N(C6H4OH)2)2](BF4)2 (P(Ph)2N(C6H4OH)2 = 1,5-bis(p-hydroxyphenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclo-octane), that catalyzes the production of H2 in aqueous acetonitrile with turnover frequencies of 750-170,000 s(-1) at experimentally determined overpotentials of 310-470 mV.

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Purpose: Profound changes of the vasculature in tumors critically impact drug delivery and therapy response. We aimed at developing a procedure to monitor morphological and functional parameters of the vasculature in subcutaneous xenograft models commonly applied for therapy testing by using probe-based confocal laser endomicroscopy.

Procedures: By monitoring various normal and diseased tissues, we established an experimental and analytical set-up to systematically analyze tracer extravasation from the microvasculature.

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We present scalable large area terahertz (THz) emitters based on a nanoscale multilayer InGaAs/InAlAs heterostructure and a microstructured electrode pattern. The emitters are designed for pump lasers working at the telecommunication wavelength of 1.55 μm.

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All-optical switching (AOS) in ferrimagnetic Fe(100-x)Tb(x) alloys is presented. AOS is witnessed below, above, and in samples without a magnetic compensation point. It is found that AOS is associated with laser heating up to the Curie temperature and intimately linked to a low remanent sample magnetization.

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The first enantiospecific total synthesis of the antibacterial natural product (+)-pleuromutilin has been achieved. The approach includes the synthesis of a non-racemic cyclisation substrate from (+)-trans-dihydrocarvone, a highly selective SmI2-mediated cyclisation cascade, an electron transfer reduction of a hindered ester, and the first efficient conversion of (+)-mutilin to the target.

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We use terahertz pulses to induce resonant transitions between the eigenstates of optically generated exciton populations in a high-quality semiconductor quantum well sample. Monitoring the excitonic photoluminescence, we observe transient quenching of the 1s exciton emission, which we attribute to the terahertz-induced 1s-to-2p excitation. Simultaneously, a pronounced enhancement of the 2s exciton emission is observed, despite the 1s-to-2s transition being dipole forbidden.

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We present the results of pump–probe experiments on multilayer graphene samples performed in a wide spectral range, namely from the near infrared (photon energy 1.5 eV) to the terahertz (photon energy 8 meV) spectral range. In the near infrared, exciting carriers and probing at higher photon energies provides direct evidence for a hot carrier distribution.

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Background: Skin metastases can be defined as the spread of a tumor from its site of primary origin to the skin. Skin metastasis may be the first sign of advanced cancer or an indicator of cancer recurrence.

Objectives: To review patient data of 401 skin metastases available from our institution and compare this information to previously published studies.

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A series of Ni-based electrocatalysts, [Ni(7P(Ph)2N(C6H4X))2](BF4)2, featuring seven-membered cyclic diphosphine ligands incorporating a single amine base, 1-para-X-phenyl-3,6-triphenyl-1-aza-3,6-diphosphacycloheptane (7P(Ph)2N(C6H4X), where X = OMe, Me, Br, Cl, or CF3), have been synthesized and characterized. X-ray diffraction studies have established that the [Ni(7P(Ph)2N(C6H4X))2](2+) complexes have a square planar geometry, with bonds to four phosphorus atoms of the two bidentate diphosphine ligands. Each of the complexes is an efficient electrocatalyst for hydrogen production at the potential of the Ni(II/I) couple, with turnover frequencies ranging from 2400 to 27,000 s(-1) with [(DMF)H](+) in acetonitrile.

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Purpose: The utility of refractometric analysis for calculating the refractive index (RI) of compounded parenteral nutrient solutions for pediatric patients was examined.

Methods: An equation for calculating the RI of parenteral nutrient solutions was developed by chemical and linear regression analysis of 154 pediatric parenteral nutrient solutions. This equation was then validated by analyzing 1057 pediatric parenteral nutrition samples.

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The 17-electron radical CpCr(CO)(2)(IMe)(•) (IMe = 1,3-dimethylimidazol-2-ylidene) was synthesized by the reaction of IMe with [CpCr(CO)(3)](2), and characterized by single crystal X-ray diffraction and by electron paramagnetic resonance (EPR), IR, and variable temperature (1)H NMR spectroscopy. The metal-centered radical is monomeric under all conditions and exhibits Curie paramagnetic behavior in solution. An electrochemically reversible reduction to 18-electron CpCr(CO)(2)(IMe)(-) takes place at E(1/2) = -1.

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This review discusses the development of molecular electrocatalysts for H2 production and oxidation based on nickel. A modular approach is used in which the structure of the catalyst is divided into first, second, and outer coordination spheres. The first coordination sphere consists of the ligands bound directly to the metal center, and this coordination sphere can be used to control such factors as the presence or absence of vacant coordination sites, redox potentials, hydride donor abilities and other important thermodynamic parameters.

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