Unraveling Electron Dynamics in p-type Indium Phosphide (100): A Time-Resolved Two-Photon Photoemission Study

Renewable ("green") hydrogen production through direct photoelectrochemical (PEC) water splitting is a potential key contributor to the sustainable energy mix of the future. We investigate the potential of indium phosphide (InP) as a reference material among III-V semiconductors for PEC and photovoltaic (PV) applications. The p(2 × 2)/c(4 × 2)-reconstructed phosphorus-terminated p-doped InP(100) (P-rich p-InP) surface is the focus of our investigation. We employ time-resolved two-photon photoemission (tr-2PPE) spectroscopy to study electronic states near the band gap with an emphasis on normally unoccupied conduction band states that are inaccessible through conventional single-photon emission methods. The study shows the complexity of the p-InP electronic band structure and reveals the presence of at least nine distinct states between the valence band edge and vacuum energy, including a valence band state, a surface defect state pinning the Fermi level, six unoccupied surface resonances within the conduction band, as well as a cluster of states about 1.6 eV above the CBM, identified as a bulk-to-surface transition. Furthermore, we determined the decay constants of five of the conduction band states, enabling us to track electron relaxation through the bulk and surface conduction bands. This comprehensive understanding of the electron dynamics in p-InP(100) lays the foundation for further exploration and surface engineering to enhance the properties and applications of p-InP-based III-V-compounds for, e.g., efficient and cost-effective PEC hydrogen production and highly efficient PV cells.

Resolving electron and hole transport properties in semiconductor materials by constant light-induced magneto transport

The knowledge of minority and majority charge carrier properties enables controlling the performance of solar cells, transistors, detectors, sensors, and LEDs. Here, we developed the constant light induced magneto transport method which resolves electron and hole mobility, lifetime, diffusion coefficient and length, and quasi-Fermi level splitting. We demonstrate the implication of the constant light induced magneto transport for silicon and metal halide perovskite films. We resolve the transport properties of electrons and holes predicting the material's effectiveness for solar cell application without making the full device. The accessibility of fourteen material parameters paves the way for in-depth exploration of causal mechanisms limiting the efficiency and functionality of material structures. To demonstrate broad applicability, we further characterized twelve materials with drift mobilities spanning from 10-3 to 103 cm2V-1s-1 and lifetimes varying between 10-9 and 10-3 seconds. The universality of our method its potential to advance optoelectronic devices in various technological fields.

Photogenerated charge transfer in Dion-Jacobson type layered perovskite based on naphthalene diimide

Incorporating organic semiconducting spacer cations into layered lead halide perovskite structures provides a powerful approach to mitigate the typical strong dielectric and quantum confinement effects by inducing charge-transfer between the organic and inorganic layers. Herein we report the synthesis and characterization of thin films of novel DJ-phase organic-inorganic layered perovskite semiconductors using a naphthalene diimide (NDI) based divalent spacer cation, which is shown to accept photogenerated electrons from the inorganic layer. With alkyl chain lengths of 6 carbons, an NDI-based thin film exhibited electron mobility (based on space charge-limited current for quasi-layered 〈n〉 = 5 material) was found to be as high as 0.03 cm² V^-1 s^-1 with no observable trap-filling region suggesting trap passivation by the NDI spacer cation.

Activating a Semiconductor-Liquid Junction via Laser-Derived Dual Interfacial Layers for Boosted Photoelectrochemical Water Splitting

The semiconductor-liquid junction (SCLJ), the dominant place in photoelectrochemical (PEC) catalysis, determines the interfacial activity and stability of photoelectrodes, whcih directly affects the viability of PEC hydrogen generation. Though efforts dedicated in past decades, a challenge remains regarding creating a synchronously active and stable SCLJ, owing to the technical hurdles of simultaneously overlaying the two advantages. The present work demonstrates that creating an SCLJ with a unique configuration of the dual interfacial layers can yield BiVO₄ photoanodes with synchronously boosted photoelectrochemical activity and operational stability, with values located at the top in the records of such photoelectrodes. The bespoke dual interfacial layers, accessed via grafting laser-generated carbon dots with phenolic hydroxyl groups (LGCDs-PHGs), are experimentally verified effective, not only in generating the uniform layer of LGCDs with covalent anchoring for inhibited photocorrosion, but also in activating, respectively, the charge separation and transfer in each layer for boosted charge-carrier kinetics, resulting in FeNiOOH-LGCDs-PHGs-MBVO photoanodes with a dual configuration with the photocurrent density of 6.08 mA cm^-2 @ 1.23 V_RHE , and operational stability up to 120 h @ 1.23 V_RHE . Further work exploring LGCDs-PHGs from catecholic molecules warrants the proposed strategy as being a universal alternative for addressing the interfacial charge-carrier kinetics and operational stability of semiconductor photoelectrodes.

CVD grown GaSbxN1-x films as visible-light active photoanodes

The III-V semiconductor GaN is a promising material for photoelectrochemical (PEC) cells, however the large bandgap of 3.45 eV is a considerable hindrance for the absorption of visible light. Therefore, the substitution of small amounts of N anions by isovalent Sb is a promising route to lower the bandgap and thus increase the PEC activity under visible light. Herein we report a new chemical vapor deposition (CVD) process utilizing the precursors bis(N,N'-diisopropyl-2-methyl-amidinato)-methyl gallium (III) and triphenyl antimony (TPSb) for the growth of GaSb_xN_1-x alloys. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements show crystalline and homogeneous thin films at deposition temperatures in the range of 500-800 °C. Rutherford backscattering spectrometry (RBS) combined with nuclear reaction analysis (NRA) shows an incorporation of 0.2-0.7 at% antimony into the alloy, which results in a slight bandgap decrease (up to 0.2 eV) accompanied by enhanced sub-bandgap optical response. While the resulting photoanodes are active under visible light, the external quantum efficiencies remained low. Intriguingly, the best performing films exhibits the lowest charge carrier mobility according to time resolved THz spectroscopy (TRTS) and microwave conductivity (TRMC) measurements, which showed mobilities of up to 1.75 cm² V^-1 s^-1 and 1.2 × 10^-2 cm² V^-1 s^-1, for each timescale, respectively.

Extraction of mobile charge carrier photogeneration yield spectrum of ultrathin-film metal oxide photoanodes for solar water splitting

Light absorption in strongly correlated electron materials can excite electrons and holes into a variety of different states. Some of these excitations yield mobile charge carriers, whereas others result in localized states that cannot contribute to photocurrent. The photogeneration yield spectrum, ξ(λ), represents the wavelength-dependent ratio between the contributing absorption that ultimately generates mobile charge carriers and the overall absorption. Despite being a vital material property, it is not trivial to characterize. Here, we present an empirical method to extract ξ(λ) through optical and external quantum efficiency measurements of ultrathin films. We applied this method to haematite photoanodes for water photo-oxidation, and observed that it is self-consistent for different illumination conditions and applied potentials. We found agreement between the extracted ξ(λ) spectrum and the photoconductivity spectrum measured by time-resolved microwave conductivity. These measurements revealed that mobile charge carrier generation increases with increasing energy across haematite's absorption spectrum. Low-energy non-contributing absorption fundamentally limits the photoconversion efficiency of haematite photoanodes and provides an upper limit to the achievable photocurrent that is substantially lower than that predicted based solely on absorption above the bandgap. We extended our analysis to TiO₂ and BiVO₄ photoanodes, demonstrating the broader utility of the method for determining ξ(λ).

Comparative Study of Photocarrier Dynamics in CVD-deposited CuWO4, CuO, and WO3 Thin Films for Photoelectrocatalysis

The temporal evolution of photogenerated carriers in CuWO4, CuO and WO3 thin films deposited via a direct chemical vapor deposition approach was studied using time-resolved microwave conductivity and terahertz spectroscopy to obtain the photocarrier lifetime, mobility and diffusion length. The carrier transport properties of the films prepared by varying the copper-to-tungsten stoichiometry were compared and the results related to the performance of the compositions built into respective photoelectrochemical cells. Superior carrier mobility was observed for CuWO4 under frontside illumination.

Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes

Cuprous oxide (Cu₂O) is a promising material for solar-driven water splitting to produce hydrogen. However, the relatively small accessible photovoltage limits the development of efficient Cu₂O based photocathodes. Here, femtosecond time-resolved two-photon photoemission spectroscopy has been used to probe the electronic structure and dynamics of photoexcited charge carriers at the Cu₂O surface as well as the interface between Cu₂O and a platinum (Pt) adlayer. By referencing ultrafast energy-resolved surface sensitive spectroscopy to bulk data we identify the full bulk to surface transport dynamics for excited electrons rapidly localized within an intrinsic deep continuous defect band ranging from the whole crystal volume to the surface. No evidence of bulk electrons reaching the surface at the conduction band level is found resulting into a substantial loss of their energy through ultrafast trapping. Our results uncover main factors limiting the energy conversion processes in Cu₂O and provide guidance for future material development.

While cuprous oxide is a promising solar-to-fuel conversion material, photoelectrochemical devices substantially underperform. Here, the authors use femtosecond time-resolved two-photon photoemission spectroscopy to correlate photoexcited electron energetics and dynamics with performance losses.

Charge Carrier Lifetimes in Cr-Fe-Al-O Thin Films

The effect of compositional variation on charge carrier lifetimes of Cr₁Fe_0.84Al_0.16O₃, a promising material for solar water splitting recently identified using combinatorial materials science, is explored using ultrafast time-resolved optical reflectance. The transient signal can be described by a biexponential decay, where the shorter time constant varies over 1 order of magnitude with changing Cr content while the longer one stays constant. Intrinsic performance limitations such as a low charge carrier mobility on the order of 10^-3 cm²/(Vs) are identified. Charge carrier lifetime and mobility are discussed as screening criteria for solar water splitting materials.

[The ulm emergency algorithm for the acute treatment of drug-induced, bradykinin-mediated angioedema]

BACKGROUND

Bradykinin-mediated, drug-induced edema like ACE-inhibitor-induced angioedema (ACEi AE) is almost exclusively located in the head and neck region and is potentially life threatening. To date, there are no guidelines or officially-approved treatments available for this pathology.

OBJECTIVES

We sought to provide a structured therapeutic algorithm for the acute treatment of drug-induced bradykinin-mediated angioedema.

MATERIALS AND METHODS

We analyzed data (especially the course of disease and therapy) of all patients with acute angioedema, who presented to the Department of Otorhinolaryngology, Head and Neck Surgery at the University of Ulm (2010-2015). We also conducted a literature review on PubMed with the terms "acute angioedema", "angioedema emergency", "ACE angioedema", "bradykinin angioedema" and "angioedema therapy". Other fundamental references were the recent German guidelines "hereditary angioedema", "anaphylaxis" and "airway management".

RESULTS

An emergency algorithm was generated as a flowchart for the acute therapy of bradykinin-mediated drug-induced angioedema was generated. We focused on the decision criteria for intubation/airway management and pharmacological therapy: antihistamines and glucocorticoids versus anti-bradykinin treatment. Furthermore, recommendations for inpatient monitoring have been derived.

CONCLUSION/DISCUSSION

To date, therapy of drug-induced bradykinin-mediated angioedema is performed according to an "off-label" use and without officially-approved guidelines. The presented emergency algorithm provides a first approach for a structured therapeutic concept for a potentially life-threatening pathology.

Highly (001)-textured p-type WSe2 Thin Films as Efficient Large-Area Photocathodes for Solar Hydrogen Evolution

Highly (001)-textured, photoactive WSe₂ thin films have been prepared by an amorphous solid-liquid-crystalline solid process promoted by palladium. By increasing the thickness of the Pd promoter film (≥10 nm) the structure and texture of the WSe₂ films can be improved significantly. However, these as-crystallized WSe₂ films are only weakly photoactive in a 0.5 М H₂SO₄ electrolyte under AM 1.5 solar irradiation which we attribute to an inefficient photogenerated charge transfer across the WSe₂/electrolyte interface via the prevailing van der Waals planes of the WSe₂ crystallites. In this work photochemically deposited platinum on the p-type WSe₂ photocathode is used for an efficient electron transfer thus inducing the hydrogen evolution reaction. Upon illuminating the WSe₂ photocathodes in a Pt-ion containing electrolyte, the photogenerated electrons reduce Pt⁺ to Pt leading to the precipitation of Pt islands, preferentially at edge steps of the WSe₂, i.e. at the grain boundaries of the WSe₂ crystallites. The increasing amount of Pt islands at the grain boundaries linearly enhances the photocurrent density up to 2.5 mA cm⁻² at 0 V_RHE in sulfuric acid, the highest reported value up to now for WSe₂ thin films.

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF₂ vapor etch. The resulting GaP films have surface roughnesses below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10¹⁷ cm^-3 that exhibited mobilities as high as 16 cm²V^-1s^-1. Due to their unique optical properties, these films hold much promise for use in advanced optical devices.

Polymorphism of CsGaS2– structural characterization of a new two-dimensional polymorph and study of the phase-transition kinetics

Anionic layers in CsGaS₂undergo a transition to infinite strands at high temperature and transfer back under pressure.

Regulatory T cell frequencies are increased in preterm infants with clinical early-onset sepsis

The predisposition of preterm neonates to invasive infection is, as yet, incompletely understood. Regulatory T cells (Tregs ) are potential candidates for the ontogenetic control of immune activation and tissue damage in preterm infants. It was the aim of our study to characterize lymphocyte subsets and in particular CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) Tregs in peripheral blood of well-phenotyped preterm infants (n = 117; 23 + 0 - 36 + 6 weeks of gestational age) in the first 3 days of life in comparison to term infants and adults. We demonstrated a negative correlation of Treg frequencies and gestational age. Tregs were increased in blood samples of preterm infants compared to term infants and adults. Notably, we found an increased Treg frequency in preterm infants with clinical early-onset sepsis while cause of preterm delivery, e.g. chorioamnionitis, did not affect Treg frequencies. Our data suggest that Tregs apparently play an important role in maintaining maternal-fetal tolerance, which turns into an increased sepsis risk after preterm delivery. Functional analyses are needed in order to elucidate whether Tregs have potential as future target for diagnostics and therapeutics.

A high-throughput chromatin immunoprecipitation approach reveals principles of dynamic gene regulation in mammals

Understanding the principles governing mammalian gene regulation has been hampered by the difficulty in measuring in vivo binding dynamics of large numbers of transcription factors (TF) to DNA. Here, we develop a high-throughput Chromatin ImmunoPrecipitation (HT-ChIP) method to systematically map protein-DNA interactions. HT-ChIP was applied to define the dynamics of DNA binding by 25 TFs and 4 chromatin marks at 4 time-points following pathogen stimulus of dendritic cells. Analyzing over 180,000 TF-DNA interactions we find that TFs vary substantially in their temporal binding landscapes. This data suggests a model for transcription regulation whereby TF networks are hierarchically organized into cell differentiation factors, factors that bind targets prior to stimulus to prime them for induction, and factors that regulate specific gene programs. Overlaying HT-ChIP data on gene-expression dynamics shows that many TF-DNA interactions are established prior to the stimuli, predominantly at immediate-early genes, and identified specific TF ensembles that coordinately regulate gene-induction.

Directional limits on persistent gravitational waves using LIGO S5 science data

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

Contribution of different placental cells to the expression and stimulation of antimicrobial proteins (AMPs)

The placenta is a major barrier that prevents potentially infectious agents from causing fetal diseases or related complications during pregnancy. Therefore, we postulated that the placenta might express a broad repertoire of antimicrobial proteins as well as inflammatory chemokines and cytokines to combat invading microorganisms. Here we demonstrate that placental cells indeed express a wide range of AMPs (antimicrobial peptides and proteins) including bactericidal/permeability-increasing protein (BPI), secretory leukocyte protease inhibitor (SLPI), human β-defensin 2 (hBD2), acyloxyacyl hydrolase (AOAH), and cathelicidin (CAP18). In addition, these cells also secrete pro-inflammatory cytokines and chemokines upon stimulation with bacterial ligands. Notably, we show that BPI expression by placental cells could be completely attributed to granulocytes while highly purified placental trophoblasts expressed only a subset of the AMPs like SLPI. Unexpectedly, trophoblast AMPs did not exhibit inducible secretion in response to various TLR ligands and further investigations showed that the unresponsiveness of trophoblasts to lipopolysaccharide (LPS) was due to a lack of TLR4 expression. In summary, we have shown that the expression of different AMPs can be allocated to various cells in the placenta and the repertoire of the AMPs expressed by placental cells is a result of a cooperation of leukocytes as well as cells from embryonic origin.

Translational, rotational, and vibrational coupling into phase in diffractively coupled optical cavities

All-reflective optical systems are under consideration for future gravitational wave detector topologies. A key feature of these all-reflective systems is the use of Fabry-Perot cavities with diffraction gratings as input couplers; however, theory predicts and experiment has shown that translation of the grating surface across the incident laser light will introduce additional phase into the system. This translation can be induced through simple side-to-side motion of the coupler, yaw motion of the coupler around a central point (i.e., rotation about a vertical axis), and even via internal resonances (i.e., vibration) of the optical element. In this Letter we demonstrate on a prototype-scale suspended cavity that conventional cavity length-sensing techniques used to detect longitudinal changes along the cavity axis will also be sensitive to translational, rotational, and vibrational motion of the diffractive input coupler. We also experimentally verify the amplitude response and frequency dependency of the noise coupling as given by theory.

Sensitivity and specificity of herpes simplex virus-2 serological assays among HIV-infected and uninfected urban Ugandans

Herpes simplex virus type 2 (HSV-2) is a risk factor for HIV-1 infection. We characterized HSV-2 serology assay performance in HIV-positive and HIV-negative Africans. Serostatus for HSV-2 and HIV-1 was determined in 493 serum specimens stored from a community HSV-2 prevalence survey in Kampala, Uganda. HSV-2 serology by Focus HerpeSelect ELISA, Biokit HSV-2 rapid assay and Kalon HSV-2 was compared with HSV-2 Western blot (WB) according to HIV-1 serostatus. Sensitivity/specificity was: 99.5%/70.2% for Focus, 97.0%/86.4% for Biokit and 97.5%/96.2% for Kalon. Focus with Biokit confirmation improved sensitivity/specificity (99.4%/96.8%, respectively). Use of a higher Focus index value cut-off of 2.2 instead of 1.1 increased specificity from 70.2% to 92.4%. Kalon had higher specificity than Focus (P < 0.001). Of commercially available HSV-2 serological assays, Kalon alone, or Focus ELISA followed by Biokit confirmation perform best. Improved HSV-2 assays are needed for HSV-2 and HIV-1 public health activities in Africa.

Angiotensin II receptor blocker induced fetopathy: 7 cases

BACKGROUND

During a period of 12 months 7 newborns with a partially severe fetopathy caused most probably by maternal sartan-intake in pregnancy were treated in 5 German teaching hospitals. Sartans antagonize the effect of angiotensin II at the AT1-receptor and are used to treat arterial hypertension.

METHOD

We presented 2 cases at the yearly GNPI meeting 2010 and we were informed about similar cases in other German teaching hospitals which we brought together in this publication.

RESULTS

In the presented cases, maternal sartan intake was noticed at different times in pregnancy and was in part discontinued some weeks before delivery. In all pregnancies oligohydramnios was present and fetal kidneys displayed a hyperechogenic structure on ultrasound. The newborns' postnatal course varied: oligohydramnios sequence with lung hypoplasia, arterial hypotension and renal insufficiency were the predominant problems of the first days of life. The majority (4/7) of infants did not survive this period, in other cases there was a complete (1/7) recovery of renal function whereas others survived with renal impairment (2/7), in part requiring chronic dialysis. Further distinctive features seen frequently were disturbances of cranial ossification and flaccid paralysis of hands and feet with deviations as well as sensorineural hearing loss.

CONCLUSION

These case reports again underline the hazardousness of maternal sartan intake with potential fatal outcome for the newborn. Though the use of sartans in pregnancy is contraindicated and several case reports of sartan induced fetopathies exist, the risk of sartan treatment generally seems to be underestimated.

A scalable, fully automated process for construction of sequence-ready human exome targeted capture libraries

Genome targeting methods enable cost-effective capture of specific subsets of the genome for sequencing. We present here an automated, highly scalable method for carrying out the Solution Hybrid Selection capture approach that provides a dramatic increase in scale and throughput of sequence-ready libraries produced. Significant process improvements and a series of in-process quality control checkpoints are also added. These process improvements can also be used in a manual version of the protocol.

Sexual and demographic determinants for herpes simplex virus type 2 among fishermen along Lake Victoria, Kenya

OBJECTIVES

To determine the prevalence and correlates of herpes simplex virus type 2 (HSV-2) seropositivity among fishermen along the shores of Lake Victoria in Kisumu district, Kenya.

METHODS

Sera from a random sample of 250 fishermen from 18 beaches were collected after a detailed sociodemographic interview. HSV-2 infection was tested by Kalon HSV-2 ELISA.

RESULTS

The HSV-2 seroprevalence was 63.9%. In multivariate analysis, fishermen were more likely to be infected with HSV-2 if they were HIV positive (prevalence ratio (PR) 1.27; 95% CI 1.06 to 1.52) compared with those testing HIV negative, were aged 18-20 (PR 0.49; 95% CI 0.24 to 0.99) and older than 40 (PR 1.66; 95% CI 1.30 to 2.14) years compared with those aged 21-25 years, perceived their last two sexual partners to have a sexually transmitted infection (STI; PR 1.27; 95% CI 1.06 to 1.52) compared with those who did not and were more likely to be circumcised (PR 1.49; 95% CI 1.19 to 1.86).

CONCLUSIONS

HSV-2 seroprevalence is high among this population and is associated with HIV serostatus, age, perception about partner's STI status and circumcision.

Specific status and pathogenicity of syngamid nematodes in bird species (Ciconiformes, Falconiformes, Gruiformes) from Germany

A total of 549 birds from four orders were examined for nematodes in their respiratory system from 1995 to 2000. Twelve individuals of Falconiformes (n = 503), one of Gruiformes (n = 22) and one of Ciconiformes (n = 1), but no bird of the order Strigiformes (n = 23) were infected with syngamids. The syngamid species included Hovorkonema variegatum, Syngamus trachea and Cyathostoma trifurcatum from the trachea, bronchi and air sacs, with H. variegatum being the most prevalent. Cyathostoma trifurcatum from a black stork Ciconia nigra is a new record for Germany. The marsh harrier Circus aeruginosus and the white-tailed sea eagle Haliaeetus albicilla are new hosts for H. variegatum. Morphological characters such as the dorsal rays of the bursa copulatrix, length of the spicules and the mouth capsule are used to differentiate species of the family Syngamidae. Egg size is different between S. trachea and H. variegatum. In addition to morphological characters, the nucleotide sequence of the SSU ribosomal gene was determined for H. variegatum. Pairwise comparisons with the SSU sequence of S. trachea (AF036606) revealed sequence difference of 2.6%. The nucleotide sequence of the second internal transcribed spacer of ribosomal DNA for different populations of H. variegatum was also determined. Pairwise comparisons revealed two separate strains with a sequence difference of 14.0% to 14.5% suggesting the existence of a cryptic species. Pathological findings associated with H. variegatum were found in 7 of 12 cases and consisted of thickened air sac walls and lesions or granuloma at the site of attachment of the worm, which occasionally involved the underlaying tissues. Lymphoplasmocytic air sacculitis was the most prominent histological lesion found.

Efficacy of Waiting Periods and Topical Fluoride Treatment on Toothbrush Abrasion of Eroded Enamel in situ

The aim of this study was to investigate the effectiveness of both waiting periods between acid exposure and tooth brushing and fluoride applications in preventing toothbrush abrasion of acid-softened enamel surfaces. The study, on 5 subjects, had an in situ crossover design with experimental periods of 5 days each. Human enamel samples were recessed in mouth appliances and at the end of each experimental period, enamel loss was determined profilometrically. Specimens were eroded extraorally (2 x 20 min per day; 0.05 M citric acid), standardized brushing (2 x 30 s per sample per day; powered toothbrush) was performed in situ. The groups were: (1) erosion only, (2) brushing with fluoride-free toothpaste directly after, (3) 2 h after, or (4) before erosion; fluoride application was either (5) brushing with a fluoride toothpaste or (6) brushing with a fluoride toothpaste or gel, and rinsing with a fluoride mouth rinse. Enamel loss was (1) 45.2 +/- 10.8, (2) 79.3 +/- 7.8, (3) 81.7 +/- 9.5, (4) 69.7 +/- 13.8, (5) 51.5 +/- 13.0, and (6) 41.2 +/- 1.8 microm. Brushing without fluoride increased the enamel loss significantly (p < or = 0.001), waiting for 2 h had no protective effect, and brushing before erosion decreased enamel loss values only by 12% (n.s.). In the fluoride groups, enamel loss was significantly lower than after brushing with the fluoride-free toothpaste and comparable to values after erosion only (n.s.). Waiting periods had only a minor effect, whilst the application of fluoride appeared promising.

Performance of a novel test for IgM and IgG antibodies in subjects with culture-documented genital herpes simplex virus-1 or -2 -infection

Novel tests (BioPlex) for herpes simplex virus-1 (HSV-1) and HSV-2 IgG were compared with HerpeSelect HSV-1 and HSV-2 ELISAs for type-specific IgG. The sensitivity and specificity of BioPlex HSV-1 IgG were 94% (84/89) and 96% (119/124), respectively, with unselected sera, while the sensitivity and specificity of BioPlex HSV-2 IgG were 92% (109/118) and 98% (95/97), respectively. BioPlex IgM was compared with Diamedix IgM against sera from patients with culture-documented genital herpes. The test results were concordant in 81% of sera from HSV-1 patients and in 90% of sera from HSV-2 patients. Use of BioPlex IgM in addition to BioPlex IgG tests increased HSV-2 seroconversion detection from 47% of subjects to 70%. Use of Diamedix IgM in addition to Focus IgG ELISA increased HSV-2 detection from 40% of subjects to 70%. IgM was detected by BioPlex in 63% of sera from patients with early HSV-2 infection (< 30 days) and in 59% of sera by Diamedix. IgM was also detected in a large proportion of sera from subjects with established HSV-2 infection (33% by BioPlex and 29% by Diamedix). Addition of IgM testing substantially increased the ability to detect seroconversion early in infection. IgM is an indicator of recent infection only in subjects who lack detectable IgG.

Genome sequence, comparative analysis and haplotype structure of the domestic dog

Here we report a high-quality draft genome sequence of the domestic dog (Canis familiaris), together with a dense map of single nucleotide polymorphisms (SNPs) across breeds. The dog is of particular interest because it provides important evolutionary information and because existing breeds show great phenotypic diversity for morphological, physiological and behavioural traits. We use sequence comparison with the primate and rodent lineages to shed light on the structure and evolution of genomes and genes. Notably, the majority of the most highly conserved non-coding sequences in mammalian genomes are clustered near a small subset of genes with important roles in development. Analysis of SNPs reveals long-range haplotypes across the entire dog genome, and defines the nature of genetic diversity within and across breeds. The current SNP map now makes it possible for genome-wide association studies to identify genes responsible for diseases and traits, with important consequences for human and companion animal health.

The impact of tumour volume and surgery on the outcome of adults with supratentorial WHO grade II astrocytomas and oligoastrocytomas

BACKGROUND

The study was performed to elucidate the impact of tumour volume and surgical resection on the long-term outcome of patients with supratentorial, diffuse, World Health Organization (WHO) grade II astrocytomas and oligo-astrocytomas.

METHOD

After analysing 79 adult patients consecutively diagnosed between 1991 and 2000, we selected a group of 42 patients treated by surgery without adjuvant therapy. The tumour volume was defined as the whole region of T2-hyperintensity and measured interactively on pre- and postoperative and follow-up Magnetic Resonance Imaging (MRI) using a dedicated imaging software. Volumetric, clinical, and histological data were analysed for correlation with tumour progression (TP), malignant transformation (MT), drop in functional status (DKPS) and overall survival (OS).

FINDINGS

Pre- and postoperative tumour volumes, and the involvement of more than one lobe were strongly associated with worse outcome. Preoperative tumour volume was the strongest predictor of OS (p<0.01) and the only predictor of MT (p<0.05). The absolute and relative volumes of tumour removed by surgery were not significantly associated with outcome. CONCLUSIONS. Initial tumour volume, measured as the volume of T2-hyperintensity on MRI, and tumour extension are the strongest predictors of outcome in patients with supratentorial diffuse astrocytic WHO Grade II tumours. The potential benefit of aggressive tumour resection needs to be investigated in a prospective controlled trial.

Total asymmetric synthesis of the putative structure of the cytotoxic diterpenoid (-)-sclerophytin a and of the authentic natural sclerophytins A and B

An enantioselective synthetic route to the thermodynamically most stable diastereomer of the structure assigned to sclerophytin A (5) has been realized. The required tricyclic ketone 33 was prepared by sequential Tebbe-Claisen rearrangement of lactones 29 and 30, which originated from the Diels-Alder cycloaddition of Danishefsky's diene to (5S)-5-(d-menthyloxy)-2(5H)-furanone (14). An allyl and a cyano group were introduced into the resulting adduct by means of stereocontrolled allylindation under aqueous Barbier-like conditions and by way of cyanotrimethylsilane, respectively. Following stereocontrolled nucleophilic addition of a methyl group to 33, ring A was elaborated by formation of the silyl enol ether, ytterbium triflate-catalyzed condensation with formaldehyde, O-silylation, and Cu(I)-promoted 1,4-addition of isopropylmagnesium chloride. The superfluous ketone carbonyl was subsequently removed and the second ether bridge introduced by means of oxymercuration chemistry. Only then was the exocyclic methylene group unmasked via elimination. An alternative approach to the alpha-carbinol diastereomer proceeds by initial alpha-oxygenation of 37 and ensuing 1,2-carbonyl transposition. Neither this series of steps nor the Wittig olefination to follow induced epimerization at C10. Through deployment of oxymercuration chemistry, it was again possible to elaborate the dual oxygen-bridge network of the target ring system. Oxidation of the organomercurial products with O(2) in the presence of sodium borohydride furnished 72, which was readily separated from its isomer 73 after oxidation to 61. Hydride attack on this ketone proceeded with high selectivity from the beta-direction to deliver (-)-60. Comparison of the high-field (1)H and (13)C NMR properties and polarity of synthetic 5 with natural material required that structural revision be made. Following a complete spectral reassessment of the structural assignments to many sclerophytin diterpenes, a general approach to sclerophytin A, three diastereomers thereof, and of sclerophytin B was devised. The presence of two oxygen bridges as originally formulated was thereby ruled out, and absolute configurations were properly determined. Key elements of the strategy include dihydroxylation of a medium-ring double bond, oxidation of the secondary hydroxyl in the two resulting diols, unmasking of an exocyclic methylene group at C-11, and stereocontrolled 1,2-reduction of the alpha-hydroxy ketone functionality made available earlier.

Revised constitution of sclerophytins A and B

[structure: see text] Spectroscopic reevaluation of sclerophytin B, the acetate of sclerophytin A, has demonstrated unequivocally that these coral metabolites are not composed of two ether bridges.

Hydroxyoxazolidines as alpha-aminoacetaldehye equivalents: novel inhibitors of calpain

The synthesis of [1-[(5-hydroxy-4-(phenylmethyl)-3-oxazolidinyl)carbonyl]-2-ethylpropy lcarbamic acid phenylmethyl ester (2; MDL 104,903), a potent inhibitor of calpain, is described. Synthesis of related compounds, which offer insights into the mechanism of action for 2, are also described, as is an O-acetyl prodrug derivative of 2.

Measuring system for in vivo recording of force systems in orthodontic treatment-concept and analysis of accuracy

The aim of our developments is three-dimensional in vivo recording of those orthodontic force systems inducing tooth movements during treatment with fixed appliances. The concept presented here is the first to permit the forces and torques of these statically multiply undetermined systems to be recorded in vivo. For this purpose the force systems transmitted to the teeth from the archwire are isolated from the respective tooth by means of divisible special-design brackets and introduced into a 3D force torque sensor via a gripping appliance. The sensor is fixed with a purpose-developed device relative to the patient's dental arch. The patient's head is positioned relative to the system by means of a bite fork as well as a forehead and chin support. Electrical measurement of the mechanical quantities is carried out by a six-axis force torque sensor with semiconductor strain gauge elements, an electronical evaluator and a mobile measuring computer (PC). Extensive calibration of the sensor system has shown that the measuring uncertainty of the electrical measuring is less than 2%. Precise spatial fixing of bracket slot and archwire in the therapeutic position is crucial to the measuring accuracy of the system, as even minimum displacements affect the force system to be measured. Movements of the measuring system up to 0.04 mm result from a therapeutic force of 1.5 N. The results of extensive in vitro studies have already demonstrated that the system developed by us is suitable for the specified in vivo measuring function.

In vitro testing of a measuring system for in vivo recording of orthodontically applied forces and moments in the multiband technique. Part II

The aim of this study was to measure in vivo the forces and moments acting therapeutically on the individual tooth in connection with the multiband technique. Securing and evaluating the planned in vivo measurements involves analysing the measuring accuracy of the system as a whole by means of corresponding in vitro investigations. Errors in determining the therapeutically effective force system may result from the electrical measurement of the mechanical quantities by the sensor system and from the fixing of the archwire in therapeutic position. The precision of this fixing is influenced by displacements induced by elasticities and mechanical tensions in the measuring system. Calibration test series have shown the sensor system to have a margin of error of less than 2%. The displacements influencing precision fixing of the archwire were determined by means of a laser position measuring system. For a maximum orthodontic force of 1.5 N, they are 0.06 mm in the least favourable case. The resulting measuring accuracy was determined analytically or graphically, depending on the key parameters. Successful in vivo studies of the therapeutically applied force systems are to be expected on the basis of these results.

Cyclic nitrone free radical traps: isolation, identification, and synthesis of 3,3-dimethyl-3,4-dihydroisoquinolin-4-ol N-oxide, a metabolite with reduced side effects

A C-4 hydroxylated metabolite (2, 3,3-dimethyl-3,4-dihydroisoquinolin-4-ol N-oxide) of the previously described cyclic nitrone free radical trap 1 (3,3-dimethyl-3,4-dihydroisoquinoline N-oxide, a cyclic analog of phenyl-tert-butylnitrone (PBN)) was isolated, identified, and synthesized. The metabolite (2), though a less potent antioxidant than 1 in an in vitro lipid peroxidation assay, showed greatly reduced acute toxicity and sedative properties. Several analogs of 2 were prepared in attempts to improve on its weak antioxidant activity while retaining the desirable side effect profile. Effective structural changes included replacement of the gem-dimethyl moiety with spirocycloalkane groups and/or oxidation of the alcohols to the corresponding ketones. All of the analogs were more lipophilic (log k'(w)) and more active in the standard lipid peroxidation assay than 2. In addition, some of the compounds were able to protect cerebellar granule cells against oxidative damage (an in vitro model of oxidative brain injury) with IC50 values well below the value of the lead compound 1. The ketones, as predicted, were much more potent than 2 (and 1) in both of the above assays (up to ca. 200-fold). However, only compounds with a hydroxyl or an acetate group at C-4 displayed significantly reduced acute toxicity and sedative properties relative to those of 1. Importantly, the diminishment of toxicity and sedation were not the result of a lack of brain penetration as both 2 and the corresponding ketone (3,3-dimethyl-3,4-dihydro-3H-isoquinolin-4-one N-oxide) achieved equal or greater brain levels than those of 1 when administered to rats i.p.