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Laser-driven chemical vapor deposition (LCVD) is an attractive process for direct write additive manufacturing of both metals and ceramics. While LCVD offers high deposition rates and the ability t...

Some organic additive manufacturing feedstocks can be cohesive and tend to agglomerate in suspensions, which can lead to significant challenges in formulating solids-loaded fluids, like those used in many additive manufacturing processes. By depositing an ultra-thin, layer of a second material conformally with the surface of the feedstock powder, Atomic Layer Deposition (ALD) can be used to uniquely modify the surface and, thereby, cohesion of the powder material without changing the properties of the bulk material. This paper demonstrates low temperature (

Endoscopic ultrasound examination may provide complementary information to cross-sectional imaging in lesions of the liver, portal vein, and surrounding lymph nodes. With fine needle aspiration, endoscopic ultrasound examination is a powerful tool for the diagnosis of focal liver lesions and has usefulness in the evaluation of indeterminate liver lesions. Endoscopic ultrasound examination may influence hepatocellular cancer staging and Endoscopic ultrasound examination with fine needle aspiration of locoregional nodes and portal vein thromboses changes management. Contrast-enhanced endoscopic ultrasound examination and endoscopic ultrasound examination elastography are likely to expand the usefulness of endoscopic ultrasound examination in evaluating liver malignancy with technologic improvements.

Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation then rotate to remove adjoining grain boundaries, the underlying atomistic pathways for this "imperfect OA" process remain the subject of debate. In this study, molecular dynamics and in situ transmission electron microscopy (TEM) are used to probe the crystallographic evolution of up to 30 gold nanoparticles during aggregation. It is found that Imperfect OA occurs because 1) grain boundaries become quantized when their size is comparable to the separation between constituent dislocations and 2) kinetic barriers associated with the glide of grain boundary dislocations are small. In support of these findings, TEM experiments show the formation of a single crystal aggregate after annealing nine initially misoriented, agglomerated particles with evidence of dislocation activity and twin formation during particle/grain alignment. These observations motivate future work on assembled nanocrystals with tailored defects and call for a revision of Read-Shockley models for grain boundary energies in nanocrystalline materials.

Background While patients with celiac disease have increasingly developed an atypical pattern of weight gain and obesity, the role of bariatric surgery remains unclear. The primary aim of this study was to evaluate the effect of bariatric surgery on clinical outcomes among hospitalized patients with celiac disease. Methods The United States Nationwide Inpatient Sample database was queried for discharges with co-diagnoses of morbid obesity and celiac disease between 2004 and 2014. The primary outcome was in-hospital mortality. Secondary outcomes included renal failure, urinary tract infection, malnutrition, sepsis, pneumonia, respiratory failure, thromboembolic events, strictures, micronutrient deficiency, length of stay, and hospitalization costs. Using Poisson regression, adjusted incidence risk ratios (IRR) were derived for clinical outcomes in patients with prior bariatric surgery compared to those without bariatric surgery. Results Among 1499 patients with a discharge diagnosis of celiac disease and morbid obesity, 126 patients (8.4%) underwent bariatric surgery. Despite an increase in morbid obesity over the study period, the proportion of morbidly obese patients with celiac disease who had bariatric surgery declined by 18.5% (Ptrend

A simple and inexpensive method for growing Ga2O3 using GaAs wafers is demonstrated. Si-doped GaAs wafers are heated to 1050 °C in a horizontal tube furnace in both argon and air ambients in order to convert their surfaces to β-Ga2O3. The β-Ga2O3 films are characterized using scanning electron micrograph, energy-dispersive X-ray spectroscopy, and X-ray diffraction. They are also used to fabricate solar blind photodetectors. The devices, which had nanotextured surfaces, exhibited a high sensitivity to ultraviolet (UV) illumination due in part to large surface areas. Furthermore, the films have coherent interfaces with the substrate, which leads to a robust device with high resistance to thermo-mechanical stress. The photoconductance of the β-Ga2O3 films is found to increase by more than three orders of magnitude under 270 nm ultraviolet illumination with respect to the dark current. The fabricated device shows a responsivity of ~292 mA/W at this wavelength.

Direct ink writing (DIW) three-dimensional (3D) printing provides a revolutionary approach to fabricating components with gradients in material properties. Herein, we report a method for generating colloidal germania feedstock and germania-silica inks for the production of optical quality germania-silica (GeO2-SiO2) glasses by DIW, making available a new material composition for the development of multimaterial and functionally graded optical quality glasses and ceramics by additive manufacturing. Colloidal germania and silica particles are prepared by a base-catalyzed sol-gel method and converted to printable shear-thinning suspensions with desired viscoelastic properties for DIW. The volatile solvents are then evaporated, and the green bodies are calcined and sintered to produce transparent, crack-free glasses. Chemical and structural evolution of GeO2-SiO2 glasses is confirmed by nuclear magnetic resonance, X-ray diffraction, and Raman spectroscopy. UV-vis transmission and optical homogeneity measurements reveal comparable performance of the 3D printed GeO2-SiO2 glasses to glasses produced using conventional approaches and improved performance over 3D printed TiO2-SiO2 inks. Moreover, because GeO2-SiO2 inks are compatible with DIW technology, they offer exciting options for forming new materials with patterned compositions such as gradients in the refractive index that cannot be achieved with conventional manufacturing approaches.

Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (∼315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. This constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results presented here and elsewhere.

In this study, (111) silicon substrates were exposed to varied trimethylaluminum predoses and ammonia using metalorganic chemical vapor deposition and the resulting deposits were examined using AFM, SEM, TEM, STEM, EDXS, and XPS. Growth patches were observed with facets in the both the vertical and lateral directions. The width of these patches increased with increasing total volume of deposited aluminum. Their structure was found to be diamond cubic silicon with dilute concentrations of aluminum. Small, rounded AlN islands were observed on the surface of these patches which had electron diffraction patterns consistent with both strained wurtzite and zinc blende structures. A model is proposed in which silicon diffuses into liquid aluminum prior to ammonia exposure and the resulting liquid Al-Si alloy is converted into AlN and silicon upon nitridation.

This study compared 24-h nutrient oxidation responses between a sedentary condition (SED) and a condition in which short 5-min bouts of moderate-intensity physical activity were performed hourly for nine consecutive hours over 4 days (MICRO). To determine whether any shifts in fuel use were due solely to increases in energy expenditure, we also studied a condition consisting of a single isoenergetic 45-min bout of moderate-intensity exercise (ONE). Twenty sedentary overweight or obese adults (10 men/10 women; 32.4 ± 6.3 yr; BMI, 30.6 ± 2.9 kg/m2) completed all three conditions (MICRO, SED, and ONE) in a randomized order. Each condition consisted of a 3-day free-living run-in followed by a 24-h stay in a whole-room calorimeter to measure total energy expenditure (TEE) and substrate utilization. Dietary fat oxidation was also assessed during the chamber stay by administering a [1-13C] oleic acid tracer at breakfast. Energy intake was matched across conditions. Both MICRO and ONE increased TEE relative to SED, resulting in a negative energy balance. HOMA-IR improved in both activity conditions. MICRO increased 24-h carbohydrate oxidation compared with both ONE and SED ( P < 0.01 for both). ONE was associated with higher 24-h total fat oxidation compared with SED, and higher 24-h dietary fat oxidation compared with both SED and MICRO. Differences in substrate oxidation remained significant after adjusting for energy balance. In overweight and obese men and women, breaking up sitting time increased reliance upon carbohydrate as fuel over 24 h, while a single energy-matched continuous bout of exercise preferentially relies upon fat over 24 h. NEW & NOTEWORTHY Insulin sensitivity, as assessed by HOMA-IR, was improved after 4 days of physical activity, independent of frequency and duration of activity bouts. Temporal patterns of activity across the day differentially affect substrate oxidation. Frequent interruptions of sedentary time with short bouts of walking primarily increase 24-h carbohydrate oxidation, whereas an energy-matched single continuous bout of moderate intensity walking primarily increased 24-h fat oxidation.

BACKGROUND: The association between obesity and rising incidence of hepatocellular carcinoma (HCC) in the United States has been documented; however, the role of bariatric surgery remains less clear. AIM: To evaluate the cross-sectional association of prior-bariatric surgery and HCC. METHODS: The United States Nationwide Inpatient Sample (NIS) database was queried from 2004–2014 for discharges with a diagnosis of morbid obesity. Primary outcomes of interest were HCC and in-hospital mortality rate. Secondary outcomes were length of stay and cost. Baseline characteristics were balanced using propensity score matching (PSM). Using Poisson and logistic regressions, adjusted HCC prevalence ratio (PR) and mortality odds ratio (OR) were derived in patients with prior-bariatric surgery compared to those without bariatric surgery. RESULTS: Of the 2,881,414 patients included in our study, 267,082 (9.3%) underwent bariatric surgery. From 2004–2014, there was a 3-fold increase in age-adjusted prevalence of HCC from 27 per 100,000 to 72 per 100,000 (P(Trend)

We present two strategies to minimize laser damage in transparent conductive films. The first consists of improving heat dissipation by selection of substrates with high thermal diffusivity or by addition of capping layer heatsinks. The second is reduction of bulk energy absorption by lowering free carrier density and increasing mobility, while maintaining film conductance with thicker films. Multi-pulse laser damage tests were performed on tin-doped indium oxide (ITO) films configured to improve optical lifetime damage performance. Conditions where improvements were not observed are also described. When bulk heating is not the dominant damage process, discrete defect-induced damage limits damage behavior.

In this study, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performance degradation.