Erratum: Bending Rigidity of 2D Silica [Phys. Rev. Lett. 120, 226101 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.120.226101.

Bending Rigidity of 2D Silica.

A chemically stable bilayers of SiO_{2} (2D silica) is a new, wide band gap 2D material. Up till now graphene has been the only 2D material where the bending rigidity has been measured. Here we present inelastic helium atom scattering data from 2D silica on Ru(0001) and extract the first bending rigidity, κ, measurements for a nonmonoatomic 2D material of definable thickness. We find a value of κ=8.8 eV±0.5 eV which is of the same order of magnitude as theoretical values in the literature for freestanding crystalline 2D silica.

Apparatus for low temperature thermal desorption spectroscopy of portable samples.

An experimental setup for low temperature thermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements.

Successes and gaps in uptake of regular, voluntary HIV testing for hidden street- and off-street sex workers in Vancouver, Canada.

Despite evidence globally of the heavy HIV burden among sex workers (SWs) as well as other poor health outcomes, including violence, SWs are often excluded from accessing voluntary, confidential and non-coercive health services, including HIV prevention, treatment, care and support. This study therefore assessed the prevalence and association with regular HIV testing among street- and off-street SWs in Vancouver, Canada. Cross-sectional baseline data were used from a longitudinal cohort known as "An Evaluation of Sex Worker's Health Access" (AESHA; January 2010-July 2012). This cohort included youth and adult SWs (aged 14+ years). We used multivariable logistic regression to assess the relationship between explanatory variables and having a recent HIV test (in the last year). Of the 435 seronegative SWs included, 67.1% reported having a recent HIV test. In multivariable logistic regression analysis, having a recent HIV test remained significantly independently associated with elevated odds of inconsistent condom use with clients [adjusted (multivariable) odds ratios, AOR: 2.59, 95% confidence intervals [95% CIs]: 1.17-5.78], injecting drugs (AOR: 2.33, 95% CIs: 1.17-4.18) and contact with a mobile HIV prevention programme (AOR: 1.76, 95% CIs: 1.09-2.84) within the last six months. Reduced odds of having a recent HIV test was also significantly associated with being a migrant/new immigrant to Canada (AOR: 0.33, 95% CIs: 0.19-0.56) and having a language barrier to health care access (AOR: 0.26, 95% CIs: 0.09-0.73). Our results highlight successes of reaching SWs at high risk of HIV through drug and sexual pathways. To maximize the effectiveness of including HIV testing as part of comprehensive HIV prevention and care to SWs, increased mobile outreach and safer-environment interventions that facilitate access to voluntary, confidential and non-coercive HIV testing remain a critical priority, in addition to culturally safe services with language support.

A portable quartz micro balance for physical vapor deposition techniques.

A portable quartz crystal micro balance for physical vapor deposition techniques is presented. The device is used for the calibration of evaporators employed in the preparation of thin film systems that are studied in surface science. The design is based upon a portable sample setup, highly versatile and customizable. It can be transported within an ultrahigh vacuum system, stored in a sample garage and be used in front of different evaporators. Details of the setup are described. Finally, the performance of the device is demonstrated and compared to scanning tunneling microscopy measurements.

Growth and structure of crystalline silica sheet on Ru(0001).

Thin SiO2 films were grown on a Ru(0001) single crystal and studied by photoelectron spectroscopy, infrared spectroscopy and scanning probe microscopy. The experimental results in combination with density functional theory calculations provide compelling evidence for the formation of crystalline, double-layer sheet silica weakly bound to a metal substrate.

[Evaluation of intestinal hyperaemia in inflamed bowel by high resolution Contrast Harmonic Imaging (CHI)]. / Evaluation der Darmwandhyperämie entzündlicher Darmerkrankungen mittels hochauflösender echokontrastverstärkter Sonographie.

AIM: Intestinal hyperaemia is a sign of active disease in the inflamed intestine which can be detected by Doppler sonography. This technique, however, can be jeopardized by tissue motion artefacts (peristalsis), and intramural enteric vessel perfusion may be below the detection threshold. Visualisation of vessels by Contrast Harmonic Imaging (CHI) at a low Mechanical Index (low MI) is not restricted by the limitations mentioned above. Contrast Harmonic Imaging at low MI of the intestinal wall has not yet been described with high frequency probes. We therefore evaluated the validity of this method for detecting hyperaemia of the intestinal wall. METHODS: CHI at low MI was performed with a 7.5 MHz ultrasound probe in 12 patients with signs of an inflamed intestine. The contrast agent BR 1 (4.8 ml) was injected intravenously. Contrast enhancement was quantified by analysing gray scale values before and after injection of BR 1 in regions of interest within the submucosal layer. RESULTS: At about 15 sec. after injection of BR 1, arterial inflow of the contrast agent with visualisation of the feeding mesenteric vessels and intense contrast of the submucosal lamina could be observed. An increase of the gray scale values within the ROI after contrast enhancement was detected in all patients. CONCLUSION: We have shown that CHI at low MI is technically feasible for the demonstration of increased intestinal perfusion in inflammatory bowel disease by using a high resolution ultrasound probe. One possible method of quantifying the contrast enhancement is the gray scale analysis of pixels in defined regions of interest within the submucosal layer.

Electroporation-facilitated delivery of plasmid DNA in skeletal muscle: plasmid dependence of muscle damage and effect of poloxamer 188.

Electroporation has been reported to facilitate naked DNA gene transfer in skeletal muscle, but has also been implicated in the pathogenesis of electrical injuries. To assess the effects of electroporation on gene transfer, mouse quadriceps muscles were injected with the luciferase reporter plasmid VR1255 and electroporated with caliper electrodes. Intramuscular luciferase expression was increased 10- to 70-fold by electroporation, depending on the DNA dose and injection volume used. In the absence of plasmid DNA injection, electroporation of quadriceps muscles resulted in rapid elevations in serum creatine phosphokinase activity, but did not elicit visible muscle damage. However, in muscles injected with plasmid DNA and electroporated, visible lesions consistently developed in the areas proximal to electrode placement when field strengths optimal for gene transfer (300 volts/cm) were applied. The development of muscle lesions was independent of plasmid transgene expression and required the presence of plasmid in the muscle during electroporation. Co-injection of poloxamer 188 (pluronic F68) with VR1255 substantially reduced elevations in serum creatine phosphokinase activity following electroporation, but did not inhibit the development of muscle lesions. In non-electroporated muscles, co-injection of poloxamer 188 increased luciferase expression threefold. Poloxamer 188 may thus constitute a useful excipient for intramuscular delivery of naked DNA.

Sodium phosphate enhances plasmid DNA expression in vivo.

Intramuscular injection of plasmid DNA results in myofiber cell expression of proteins encoded by the DNA. The preferred vehicle for plasmid DNA injections has been saline (154 mM sodium chloride) or PBS (154 mM NaCl plus 10 mM sodium phosphate). Here, it is shown that injection of luciferase or beta-galactosidase encoding plasmid DNA in a 150 mM sodium phosphate vehicle into murine muscle resulted in a two- to seven-fold increase in transgene expression compared with DNA injected in saline or PBS. When the DNA encoded secreted alkaline phosphatase, preproinsulin or interferon, sodium phosphate vehicle increased their serum levels by two- to four-fold. When the DNA encoded mouse erythropoietin, sodium phosphate vehicle increased hematocrits by two-fold compared with DNA injected in saline. When the DNA encoded influenza nucleoprotein, sodium phosphate increased anti-nucleoprotein antibody titers by two-fold. The expression of luciferase from plasmid DNA instilled into lung was increased five-fold compared with that in vehicle without sodium phosphate. Incubation of plasmid DNA with muscle extract or serum showed that sodium phosphate protected the DNA from degradation. Thus, a change from sodium chloride to sodium phosphate vehicle can enhance the expression of plasmid DNA in a tissue, possibly by inhibiting DNA degradation. Gene Therapy (2000) 7, 1171-1182.

Risk analysis of linear accelerator radiosurgery.

PURPOSE: To evaluate the toxicity of stereotactic single-dose irradiation and to compare the own results with already existing risk prediction models. METHODS AND MATERIALS: Computed tomography (CT) or magnetic-resonance (MR) images, and clinical data of 133 consecutive patients treated with linear accelerator radiosurgery were analyzed retrospectively. Using the Cox proportional hazards model the relevance of treatment parameters and dose-volume relationships on the occurrence of radiation-induced tissue changes (edema, localized blood-brain barrier breakdown) were assessed. RESULTS: Sixty-two intraparenchymal lesions (arteriovenous malformation (AVM): 56 patients, meningioma: 6 patients) and 73 skull base tumors were selected for analysis. The median follow-up was 28.1 months (range: 9.0-58.9 months). Radiation-induced tissue changes (32 out of 135, 23.7%) were documented on CT or MR images 3.6-58.7 months after radiosurgery (median time: 17.8 months). The actuarial risk at 2 years for the development of neuroradiological changes was 25.8% for all evaluated patients, 38.4% for intraparenchymal lesions, and 14.6% for skull base tumors. The coefficient: total volume recieving a minimum dose of 10 Gy (VTREAT10) reached statistical significance in a Cox proportional hazards model calculated for all patients, intraparenchymal lesions, and AVMs. In skull base tumors, the volume of normal brain tissue covered by the 10 Gy isodose line (VBRAIN10) was the only significant variable. CONCLUSIONS: These results demonstrate the particular vulnerability of normal brain tissue to single dose irradiation. Optimal conformation of the therapeutic isodose line to the 3D configuration of the target volume may help to reduce side effects.

Prevalence, circumstances, mechanisms, and risk stratification of sudden cardiac death in unipolar single-chamber ventricular pacing.

BACKGROUND: Permanent cardiac pacing is well established for the improvement of prognosis and quality of life in patients with severe bradycardia. However, sudden cardiac death still remains an unresolved problem, as it occurs in approximately 20-30% of paced patients. This 2-year follow-up study was directed at prospectively assessing prevalence, circumstances, and mechanisms of sudden death in 2,021 permanently paced patients. METHODS AND RESULTS: During the observation period, 220 patients (11%) died (mean pacing interval, 50.5 +/- 7 months). Lethal cerebrovascular events in 66 of 220 patients (30%) and sudden death in 49 of 220 patients (23%) were the two most frequently reported modes of death. Nonsudden (first year, 20%; subsequent years, 6.9%; p less than 0.01) and sudden death mortality rate (4% versus 1.8%, p less than 0.05) were highest during the first year. Mortality was unrelated to the patient's activity status at the time of death. Sudden cardiac death occurred more often in male patients (increased risk, 1.7 versus female patients; p less than 0.001) and patients younger than 60 years of age (5.2 versus patients older than 60 years, p less than 0.001). Patients with severe bradycardia (sudden death rate, 28%), severe atrioventricular block (25%), or atrial fibrillation with low ventricular rate (25%) before pacemaker implantation were more likely to suffer from sudden cardiac death than patients with previous syncopal attacks (sudden death rate, 15%) or sick sinus syndrome (17%). The highest incidence of sudden death was observed in patients with bifascicular and trifascicular bundle branch block. In this group, 35% of patients died suddenly during the follow-up period compared with 18% of patients without bundle branch block. In a subsequent study in 90 consecutive patients with various types of bundle branch block, undersensing of up to 13% of ectopic ventricular beats occurred in patients with bifascicular block. Pacing-induced tachyarrhythmias and ventricular fibrillation were documented in 10% of undersensed ectopic ventricular beats as well as in the setting of atrial fibrillation associated with ventricular arrhythmias. CONCLUSIONS: Young age, male sex, and a severely diseased heart indicated by the presence of bifascicular and trifascicular bundle branch block are the strongest predictive clinical parameters for sudden cardiac death, especially in the first year after pacemaker implantation.

Studies on segmental differences in sensitivity to adrenergic agonists in pulmonary arteries isolated from the guinea-pig.

This study was designed to examine the existence and possible mechanisms of segmental differences in sensitivity to adrenergic substances in the pulmonary vasculature of the guinea pig. The main pulmonary artery was found to be less sensitive to epinephrine, norepinephrine and phenylephrine than its left and right main branches. Because there were no differences in sensitivities between the left and right branches, most comparisons were made between the main and left branches. The difference in sensitivity was larger for adrenergic agonists which are known to be taken up by adrenergic neurons (epinephrine, norepinephrine, phenylephrine) than for an agonist which is not taken up by these neurons (methoxamine). The left artery from reserpine-treated animals was only slightly more sensitive (1.5-fold) to barium chloride than the main pulmonary artery. Cocaine potentiated to a greater extent in the main than in the left pulmonary artery the amines which are taken up by adrenergic neurons. The left arterial branch was less responsive to transmural electrical stimulation than the main artery in the absence and presence of cocaine. [3H]Norepinephrine uptake was larger in main arterial segments than in the branches and histochemical fluorescence studies demonstrated a greater degree of adrenergic innervation in the proximal segments. The results indicate that a major explanation for the differences in sensitivity between the vascular segments is a smaller degree of adrenergic neuronal uptake of agonist in the arterial branches.