Models for quantitative charge imaging by atomic force microscopy

Two models are presented for quantitative charge imaging with an atomic-force microscope. The first is appropriate for noncontact mode and the second for intermittent contact (tapping) mode imaging. Different forms for the contact force are used to demonstrate that quantitative charge imaging is possible without precise knowledge of the contact interaction. From the models, estimates of the best charge sensitivity of an unbiased standard atomic-force microscope cantilever are found to be on the order of a few electrons

Localized charge injection in SiO_2 films containing silicon nanocrystals

An atomic-force microscope (AFM) is used to locally inject, detect, and quantify the amount and location of charge in SiO2 films containing Si nanocrystals (size ~2–6 nm). By comparison with control samples, charge trapping is shown to be due to nanocrystals and not ion-implantation-induced defects in samples containing ion-beam-synthesized Si nanocrystals. Using an electrostatic model and AFM images of charge we have estimated the amount of charge injected in a typical experiment to be a few hundred electrons and the discharge rate to be ~35±15 e/min

Spatial and Electronic Manipulation of Silicon Nanocrystals by Atomic Force Microscopy

[As silicon-based devices shnnk, interest is increasing in fast, low-power devices sensitive to small numbers of electrons. Recent work suggests that MOS structures with large arrays of Si nanocrystals comprising a floating gate can be extremely fast, reliable and nonvolatile relative to conventional floating gate memories. In these structures approximately one electron is stored per nanocrystal. Despite promising initial results, current devices have a distribution of charge transit times during writing of nanocrystal ensembles, which limits speed. This behavior is not completely understood, but could be related to a dispersion in oxide thicknesses, nanocrystals interface states, or shifts in the electronic bound states due to size variations. To address these limitations, we have developed an aerosol vapor synthesis/deposition technique for silicon nanocrystals with active size classification, enabling narrow distributions of nanocrystal size (~10-15% of particle in the 2-10 nm size range). The first goal of these experiments has been to use scanning probe techniques to perform particle manipulation and to characterize particle electronic properties and charging on a single-particle basis. Si nanocrystal structures (lines, arrows and other objects) have been formed by contact-mode operation and subsequently imaged in noncontact mode without additional particle motion. Further, single nanocrystal charging by a conducting AFM tip has been observed, detected as an apparent height change due to electrostatic force, followed by a slow relaxation as the stored charge dissipates. Ongoing and future efforts will also be briefly discussed, including narrowing of nanocrystal size distributions, control of oxide thickness on the nanocrystals, and measurements of electron transport through individual particles and ensembles

Topical haemostatic agents in liver surgery: do we need them?

AbstractBackgroundWorldwide, partial liver resections are increasingly being performed for primary or secondary hepatic malignancies. There are various techniques to reduce blood loss druing liver surgery. Several topical haemostatic agents have been developed to improve haemostasis of the resection surface and these agents are used more and more, even although the true effects remain unclear.MethodsThe present literature about the use of topical haemostatic agents in liver surgery was reviewed. Furthermore we conducted a Dutch national survey to explore the use of and belief in these agents in liver surgery.ResultsThe Dutch national survey among surgeons showed that topical haemostatic agents are frequently used not only to lower intra-operative blood loss or shorten time to haemostasis, but even more importantly, to reduce resection surface related complications such as bile leakage, postoperative haemorrhage and abscess formation. Although various topical haemostatic agents have been shown to reduce intra-operative time to haemostasis at the resection surface after liver resections, there is no scientific proof that these topical haemostatic agents really reduce resection surface related complications.ConclusionThis review highlights the need for more randomized clinical trials to investigate the efficacy of topical haemostatic agents in reducing resection surface related complications

Aerosol silicon nanoparticles for use in semiconductor device fabrication

A stratum or discontinuous monolayer of dielectric-coated semiconductor particles includes a high density of semiconductor nanoparticles with a tightly controlled range of particle sizes in the nanometer range. In an exemplary embodiment, the nanoparticles of the stratum are substantially the same size and include cores which are crystalline, preferably single crystalline, and include a density which is approximately the same as the bulk density of the semiconductor material of which the particle cores are formed. In an exemplary embodiment, the cores and particles are preferably spherical in shape. The stratum is characterized by a uniform particle density on the order of 10.sup.12 to 10.sup.13 particles/cm.sup.2. A plurality of adjacent particles contact each other, but the dielectric shells provide electrical isolation and prevent lateral conduction between the particles of the stratum. The stratum includes a density of foreign atom contamination of less than 10.sup.11 atoms/cm.sup.2. The stratum is advantageously used as the floating gate in a non-volatile memory device such as a MOSFET. The non-volatile memory device including the discontinuous floating gate of semiconductor nanoparticles exhibits excellent endurance behavior and long-term non-volatility

ARGOS - IV. The kinematics of the Milky Way bulge

We present the kinematic results from our ARGOS spectroscopic survey of the Galactic bulge of the Milky Way. Our aim is to understand the formation of the Galactic bulge. We examine the kinematics of about 17 400 stars in the bulge located within 3.5 kp

The Radial Velocity Experiment (rave): Second Data Release

We present the second data release of the Radial Velocity Experiment (RAVE), an ambitious spectroscopic survey to measure radial velocities and stellar atmosphere parameters (temperature, metallicity, surface gravity, and rotational velocity) of up to one million stars using the 6 dF multi-object spectrograph on the 1.2 m UK Schmidt Telescope of the Anglo-Australian Observatory (AAO). The RAVE program started in 2003, obtaining medium resolution spectra (median R = 7500) in the Ca-triplet region (8410-8795 ) for southern hemisphere stars drawn from the Tycho-2 and SuperCOSMOS catalogues, in the magnitude range 9 < I < 12. Following the first data release, the current release doubles the sample of published radial velocities, now containing 51,829 radial velocities for 49,327 individual stars observed on 141 nights between 2003 April 11 and 2005 March 31. Comparison with external data sets shows that the new data collected since 2004 April 3 show a standard deviation of 1.3 km s-1, about twice as good as for the first data release. For the first time, this data release contains values of stellar parameters from 22,407 spectra of 21,121 individual stars. They were derived by a penalized χ2 method using an extensive grid of synthetic spectra calculated from the latest version of Kurucz stellar atmosphere models. From comparison with external data sets, our conservative estimates of errors of the stellar parameters for a spectrum with an average signal-to-noise ratio (S/N) of 40 are 400 K in temperature, 0.5 dex in gravity, and 0.2 dex in metallicity. We note however that, for all three stellar parameters, the internal errors estimated from repeat RAVE observations of 855 stars are at least a factor 2 smaller. We demonstrate that the results show no systematic offsets if compared to values derived from photometry or complementary spectroscopic analyses. The data release includes proper motions from Starnet2, Tycho-2, and UCAC2 catalogs and photometric measurements from Tycho-2 USNO-B, DENIS, and 2MASS. The data release can be accessed via the RAVE Web site: http://www.rave-survey.org and through CDS

Reconciling Estimates of Cell Proliferation from Stable Isotope Labeling Experiments.

Stable isotope labeling is the state of the art technique for in vivo quantification of lymphocyte kinetics in humans. It has been central to a number of seminal studies, particularly in the context of HIV-1 and leukemia. However, there is a significant discrepancy between lymphocyte proliferation rates estimated in different studies. Notably, deuterated (2)H2-glucose (D2-glucose) labeling studies consistently yield higher estimates of proliferation than deuterated water (D2O) labeling studies. This hampers our understanding of immune function and undermines our confidence in this important technique. Whether these differences are caused by fundamental biochemical differences between the two compounds and/or by methodological differences in the studies is unknown. D2-glucose and D2O labeling experiments have never been performed by the same group under the same experimental conditions; consequently a direct comparison of these two techniques has not been possible. We sought to address this problem. We performed both in vitro and murine in vivo labeling experiments using identical protocols with both D2-glucose and D2O. This showed that intrinsic differences between the two compounds do not cause differences in the proliferation rate estimates, but that estimates made using D2-glucose in vivo were susceptible to difficulties in normalization due to highly variable blood glucose enrichment. Analysis of three published human studies made using D2-glucose and D2O confirmed this problem, particularly in the case of short term D2-glucose labeling. Correcting for these inaccuracies in normalization decreased proliferation rate estimates made using D2-glucose and slightly increased estimates made using D2O; thus bringing the estimates from the two methods significantly closer and highlighting the importance of reliable normalization when using this technique

Cardiovascular Risk Factors Are Associated With Future Cancer

BACKGROUND The extent to which co-occurrence of cardiovascular disease (CVD) and cancer is due to shared risk factors or other mechanisms is unknown. OBJECTIVES This study investigated the association of standard CVD risk factors, CVD biomarkers, pre-existing CVD, and ideal cardiovascular (CV) health metrics with the development of future cancer. METHODS This study prospectively followed Framingham Heart Study and PREVEND (Prevention of Renal and Vascular End-Stage Disease) study participants free of cancer at baseline and ascertained histology-proven cancer. This study assessed the association of baseline CV risk factors, 10-year atherosclerotic (ASCVD) risk score, established CVD biomarkers, prevalent CVD, and the American Heart Association (AHA) Life's Simple 7 CV health score with incident cancer using multivariable Cox models. Analyses of interim CVD events with incident cancer used time-dependent covariates. RESULTS Among 20,305 participants (mean age 50 +/- 14 years; 54% women), 2,548 incident cancer cases occurred over a median follow-up of 15.0 years (quartile 1 to 3: 13.3 to 15.0 years). Traditional CVD risk factors, including age, sex, and smoking status, were independently associated with cancer (p < 0.001 for all). Estimated 10-year ASCVD risk was also associated with future cancer (hazard ratio [HR]: 1.16 per 5% increase in risk; 95% confidence interval [CI] 1.14 to 1.17; p < 0.001). The study found that natriuretic peptides (tertile 3 vs. tertite 1; HR: 1.40; 95% 0:1.03 to 1.91; p 0.035) were associated with incident cancer but not high-sensitivity troponin (p 0.47). Prevalent CVD and the development of interim CV events were not associated with higher risk of subsequent cancer. However, ideal CV health was associated with tower future cancer risk (HR: 0.95 per 1-point increase in the AHA health score; 95% CI: 0.92 to 0.99; p = 0.009). CONCLUSIONS CVD risk, as captured by traditional CVD risk factors, 10-year ASCVD risk score, and natriuretic peptide concentrations are associated with increased risk of future cancer. Conversely, a heart healthy lifestyle is associated with a lower risk of future cancer. These data suggest that the association between CVD and future cancer is attributable to shared risk factors. (C) 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation

Cardiovascular disease related circulating biomarkers and cancer incidence and mortality:is there an association?

Aims Recent studies suggest an association between cardiovascular disease (CVD) and cancer incidence/mortality, but the pathophysiological mechanisms underlying these associations are unclear. We aimed to examine biomarkers previously associated with CVD and study their association with incident cancer and cancer-related death in a prospective cohort study. Methods and results We used a proteomic platform to measure 71 cardiovascular biomarkers among 5032 participants in the Framingham Heart Study who were free of cancer at baseline. We used multivariable-adjusted Cox models to examine the association of circulating protein biomarkers with risk of cancer incidence and mortality. To account for multiple testing, we set a 2-sided false discovery rat