Watching (De)Intercalation of 2D Metals in Epitaxial Graphene: Insight into the Role of Defects

Intercalation forms heterostructures, and over 25 elements and compounds are intercalated into graphene, but the mechanism for this process is not well understood. Here, the de-intercalation of 2D Ag and Ga metals sandwiched between bilayer graphene and SiC are followed using photoemission electron microscopy (PEEM) and atomistic-scale reactive molecular dynamics simulations. By PEEM, de-intercalation "windows" (or defects) are observed in both systems, but the processes follow distinctly different dynamics. Reversible de- and re-intercalation of Ag is observed through a circular defect where the intercalation velocity front is 0.5 nm s-1 ± 0.2 nm s.-1 In contrast, the de-intercalation of Ga is irreversible with faster kinetics that are influenced by the non-circular shape of the defect. Molecular dynamics simulations support these pronounced differences and complexities between the two Ag and Ga systems. In the de-intercalating Ga model, Ga atoms first pile up between graphene layers until ultimately moving to the graphene surface. The simulations, supported by density functional theory, indicate that the Ga atoms exhibit larger binding strength to graphene, which agrees with the faster and irreversible diffusion kinetics observed. Thus, both the thermophysical properties of the metal intercalant and its interaction with defective graphene play a key role in intercalation.

Lens-Free Imaging as a Sensor for Dynamic Cell Viability Detection Using the Neutral Red Uptake Assay

Neutral red is a low-cost supravital stain for determining cell viability. The standard protocol relies on a destructive extraction process to release the accumulated dye for endpoint spectrophotometric quantification. We report a non-destructive, live-cell quantification of neutral red uptake using a compact lens-free system. Two light sources indentify the cell perimeter and quantify neutral red uptake. The quantification occurs during staining, thus eliminating the destructive extraction process and reducing assay time. Our system enables live quantification for continuous high-throughput screening of cell viability within confined spaces such as incubators.

Early versus delayed closure of bladder exstrophy: A National Surgical Quality Improvement Program Pediatric analysis

INTRODUCTION

Delayed closure of bladder exstrophy has become more popular; however, there is limited the evidence of its success. Existing literature focuses on intermediate and long-term outcomes, and short-term postoperative outcomes are limited by the small number of cases and varying follow-up methods.

OBJECTIVE

The objectives of the current study were to: 1) compare 30-day complications after early and delayed closure of bladder exstrophy, and 2) evaluate practice patterns of bladder exstrophy closure.

STUDY DESIGN

The National Surgical Quality Improvement Program Pediatric (NSQIPP) database from 2012 to 2015 was reviewed for all cases of bladder exstrophy closure. Early closure was defined as surgery at age 0-3 days, and delayed closure was defined as age 4-120 days at time of surgery. Demographic, clinical, and peri-operative characteristics were collected, as were postoperative complications, readmissions, and re-operations up to 30 days. Descriptive statistics were performed, and multivariate linear and logistic regression analyses were performed for salient complications.

RESULTS

Of 128 patients undergoing bladder exstrophy closure, 62 were included for analysis, with 44 (71%) undergoing delayed closure. Mean anesthesia and operative times were greater in the delayed closure group, and were associated with more concurrent procedures, including inguinal hernia repairs and osteotomies. The delayed closure group had a higher proportion of 30-day complications, due to a high rate of blood transfusion (57% vs 11%). Wound dehiscence occurred in 6/44 (14%) delayed closures, as compared with 0/18 (0%) early closures. When compared with prior published reports of national data from 1999 to 2010, delayed closure was performed more frequently in this cohort (71% vs 27%).

DISCUSSION

The NSQIPP provides standardized reporting of peri-operative characteristics and 30-day complications, allowing a comparison of early to delayed closure of bladder exstrophy across multiple institutions. Assessing short-term risks in conjunction with long-term follow-up is crucial for determining optimal management of this rare but complex condition.

CONCLUSION

Delayed closure of bladder exstrophy is performed frequently, yet it carries a high rate of 30-day complications worthy of further investigation. This can be useful in counseling patients and families, and to understand practice patterns across the country.

Dielectric Spectroscopic Detection of Early Failures in 3-D Integrated Circuits

The commercial introduction of three dimensional integrated circuits (3D-ICs) has been hindered by reliability challenges, such as stress related failures, resistivity changes, and unexplained early failures. In this paper, we discuss a new RF-based metrology, based on dielectric spectroscopy, for detecting and characterizing electrically active defects in fully integrated 3D devices. These defects are traceable to the chemistry of the insolation dielectrics used in the through silicon via (TSV) construction. We show that these defects may be responsible for some of the unexplained early reliability failures observed in TSV enabled 3D devices.

Metal work-function-dependent barrier height of Ni contacts with metal-embedded nanoparticles to 4H-SiC

Metal, typically gold [Au], nanoparticles [NPs] embedded in a capping metal contact layer onto silicon carbide [SiC] are considered to have practical applications in changing the barrier height of the original contacts. Here, we demonstrate the use of silver [Ag] NPs to effectively lower the barrier height of the electrical contacts to 4H-SiC. It has been shown that the barrier height of the fabricated SiC diode structures (Ni with embedded Ag-NPs) has significantly reduced by 0.11 eV and 0.18 eV with respect to the samples with Au-NPs and the reference samples, respectively. The experimental results have also been compared with both an analytic model based on Tung's theory and physics-based two-dimensional numerical simulations.

A comparative study of hair shafts in scalp psoriasis and seborrheic dermatitis using atomic force microscopy

BACKGROUND

As the inflammatory scalp conditions share similar clinical manifestations of scaling, inflammation, and pruritus, the differential diagnosis of these lesions; especially between scalp psoriasis (SP) and seborrheic dermatitis (SD) is sometimes difficult.

OBJECTIVES

The aim of this study was to investigate the differences on the hair surface in SP and SD for a clinical diagnosis, using atomic force microscopy (AFM).

METHODS

The hair shafts of 14 patients and 28 patients with SP and SD respectively, were taken from the lesional region. Hairs from healthy adults not having any hair diseases were also examined in the same way for the controls. Surface characteristics of SP and SD-affected hair shafts such as, pitting, scale thickness, and roughness, were observed on the AFM images.

RESULTS

One hundred percentage and four percentage of the patients with SP and SD respectively had macropits on their hair shafts. In both the SP and SD-affected hairs, the scale thickness was more than 4-fold than that in the control hairs. The surface of SP-affected hairs was rougher than that of SD-affected and control hairs.

CONCLUSION

The differences in hair shafts between SP and SD were investigated noninvasively using AFM. The presence of macropits could be helpful in the differentiation between SP and SD.

Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method: different doping types and plane orientations

In this study, we have fabricated nano-scaled oxide structures on GaAs substrates that are doped in different conductivity types of p- and n-types and plane orientations of GaAs(100) and GaAs(711), respectively, using an atomic force microscopy (AFM) tip-induced local oxidation method. The AFM-induced GaAs oxide patterns were obtained by varying applied bias from approximately 5 V to approximately 15 V and the tip loading forces from 60 to 180 nN. During the local oxidation, the humidity and the tip scan speed are fixed to approximately 45% and approximately 6.3 μm/s, respectively. The local oxidation rate is further improved in p-type GaAs compared to n-type GaAs substrates whereas the rate is enhanced in GaAs(100) compared to and GaAs(711), respectively, under the identical conditions. In addition, the oxide formation mechanisms in different doping types and plane orientations were investigated and compared with two-dimensional simulation results.

Crystallographic plane-orientation dependent atomic force microscopy-based local oxidation of silicon carbide

The effect of crystalline plane orientations of Silicon carbide (SiC) (a-, m-, and c-planes) on the local oxidation on 4H-SiC using atomic force microscopy (AFM) was investigated. It has been found that the AFM-based local oxidation (AFM-LO) rate on SiC is closely correlated to the atomic planar density values of different crystalline planes (a-plane, 7.45 cm-2; c-plane, 12.17 cm-2; and m-plane, 6.44 cm-2). Specifically, at room temperature and under about 40% humidity with a scan speed of 0.5 μm/s, the height of oxides on a- and m-planes 4H-SiC is 6.5 and 13 nm, respectively, whereas the height of oxides on the c-plane increased up to 30 nm. In addition, the results of AFM-LO with thermally grown oxides on the different plane orientations in SiC are compared.

Mullerian adenosarcoma with sarcomatous overgrowth of the cervix presenting as cervical polyp: a case report and review of the literature

An aggressive variant of adenosarcoma, mullerian adenosarcoma with sarcomatous overgrowth (MASO) in the cervix is extremely rare. This variant contains obvious, high-grade sarcoma in addition to a low-grade form. In this report, we describe a case of MASO of the uterine cervix and review the clinical and pathological features of these tumors. The patient was a 37-year-old woman with a cervical polypoid mass, which was morphologically considered as a benign endocervical polyp. Microscopically, polypoid cervical mass showed diffuse and dense malignant spindle cell proliferation around the benign endocervical glands and also an area of markedly anaplastic and pleomorphic spindle cell proliferation, so called, sarcomatous overgrowth. Total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymph node dissection were performed. The patient has been followed-up and neither chemotherapy nor other adjuvant therapies have been administered. At present, she has been clinically free of disease for 9 months since she received surgery. It is extremely rare that MASO of the uterine cervix is presented in premenopausal woman. Gynecologists and pathologists should be aware of the difficulties associated with a delay in the diagnosis of MASO when the tumor is present as a benign looking cervical polyp.

Interleukin-1beta regulates urokinase plasminogen activator (u-PA), u-PA receptor, soluble u-PA receptor, and plasminogen activator inhibitor-1 messenger ribonucleic acid expression in cultured human endometrial stromal cells

The interleukin-1 (IL-1) system plays an integral role in local intercellular interactions during implantation. In addition, the plasminogen activator system, especially urokinase plasminogen activator (u-PA), plasminogen activator inhibitor (PAI-1), and u-PA receptor (u-PAR), are crucial during embryo implantation. Decidualization and implantation are complex processes dependent upon several proteases, including u-PA, and IL-1 is known to affect PA activity in several cell types. We investigated the role of IL-1beta in regulating u-PA, PAI-1, u-PAR, and soluble u-PAR messenger ribonucleic acid (mRNA) expression in cultured human endometrial stromal cells using quantitative competitive PCR. For confirmation of the mRNA data, we measured PAI-1 and u-PAR protein by enzyme-linked immunosorbent assay. Confluent stromal cell cultures treated with progesterone and estradiol for 9 days were stimulated with IL-1beta, and IL-1beta plus IL-1beta antibody for an additional 24 h. Total RNA was extracted, reverse transcribed, and coamplified using quantitative and competitive PCR with internal standards. IL-1beta increased PAI-1, u-PAR, and soluble u-PAR expression in a dose-dependent manner, and this result was reversed by anti-IL-1beta antibody treatment. u-PA mRNA expression was not dependent on IL-1beta. These results suggest that IL-1 may be important in regulating PAI-1 and u-PAR during stromal cell decidualization before implantation.

The effect of cytokine mediators on prostaglandin inhibition by human decidual cells

OBJECTIVE

The purpose of this study was to determine the inhibitory effects of anti-interleukin-1beta and transforming growth factor-beta2 on the production of interleukin-1beta and prostaglandin E2 by human decidual cells.

STUDY DESIGN

Decidual membranes were obtained from 30 patients between 37 and 40 weeks' gestation. Decidual cells were isolated and grown in culture. Incubations were conducted with lipopolysaccharide as a control, lipopolysaccharide plus anti-interleukin-1beta, and lipopolysaccharide plus transforming growth factor-beta2, respectively. Interleukin-1beta and prostaglandin E2 were measured by enzyme-linked immunosorbent assay and radioimmunoassay.

RESULTS

At the end of a 24-hour culture with lipopolysaccharide plus anti-interleukin-1beta, anti-interleukin-1beta decreased the lipopolysaccharide-induced prostaglandin E2 production significantly at the concentrations of 50 ng/mL, 100 ng/mL, and 500 ng/mL (P < .05) and also decreased the lipopolysaccharide-induced interleukin-1beta production significantly at the concentrations of 10 ng/mL, 50 ng/mL, and 100 ng/mL (P < .05). In the medium containing lipopolysaccharide plus transforming growth factor-beta2, transforming growth factor-beta2 also decreased the lipopolysaccharide-induced prostaglandin E2 production significantly at the concentrations of 1 ng/mL and 10 ng/mL (P < .05) but increased the lipopolysaccharide-induced interleukin-1beta production significantly at the concentration of 1 ng/mL (P < .05).

CONCLUSIONS

Lipopolysaccharide-induced prostaglandin E2 production by human decidual cells in vitro may be prevented by anti-interleukin-1beta and transforming growth factor-beta2, and interleukin-1beta production may be prevented by anti-interleukin-1beta.