Immunoglobulin A response against Gardnerella vaginalis hemolysin and sialidase activity in bacterial vaginosis

OBJECTIVE: The aim of this study was to investigate the correlation between the immunoglobulin A immune response to Gardnerella vaginalis hemolysin and sialidase activity in vaginal fluids from patients with bacterial vaginosis. STUDY DESIGN: Nonpregnant women who were examined at a gynecologic clinic, in an age range of 18 to 62 years, were enrolled. The study population comprised 131 healthy volunteers, 32 women with bacterial vaginosis that was positive for immunoglobulin A to Gardnerella vaginalis hemolysin, 40 women with bacterial vaginosis that was negative for immunoglobulin A to Gardnerella vaginalis hemolysin, and 19 women with Candida vaginitis. Bacterial vaginosis was diagnosed by clinical criteria and Gram stain. RESULTS: Sialidase activity was present in 75% (54/72) of patients with bacterial vaginosis. Women having bacterial vaginosis and lacking a specific immunoglobulin A response had a significantly higher level of sialidase activity than patients who had an immune response against Gardnerella vaginalis hemolysin. Sialidase activity was detected in 87% (35/40) of the former subgroup of patients with bacterial vaginosis and in 59% (19/32) of women of the latter subgroup. No sialidase activity was measured in patients with candidiasis. Specificity of the assay for healthy controls was 95% (124/131 women without sialidase activity). CONCLUSIONS: Sialidases produced by Prevotella bivia and other microorganisms present in the microflora of patients with bacterial vaginosis are very likely a virulence factor not only by destroying the mucins and enhancing adherence of bacteria but also by impairing a specific immunoglobulin A immune response against other virulence factors such as cytotoxin from Gardnerella vaginalis

Electrical Compact Modeling of Graphene Base Transistors

Following the recent development of the Graphene Base Transistor (GBT), a new electrical compact model for GBT devices is proposed. The transistor model includes the quantum capacitance model to obtain a self-consistent base potential. It also uses a versatile transfer current equation to be compatible with the different possible GBT configurations and it account for high injection conditions thanks to a transit time based charge model. Finally, the developed large signal model has been implemented in Verilog-A code and can be used for simulation in a standard circuit design environment such as Cadence or ADS. This model has been verified using advanced numerical simulation

Synthesis, crystallographic characterization, and mechanical behavior of alumina chromia alloys

Powder mixtures of Alumina and Chromia, blended in different proportions (1, 3, 5 and 10%wt) by attrition milling, were fired either by pressureless sintering in air and hot pressing under vacuum. The resulting materials, characterized by X-ray diffraction, Raman spectroscopy, SEM, hardness and fracture toughness showed that all the compositions form complete solid solution which maintain the same crystal structures of corundum; chromia addition retards materials' densification of pressureless fired samples but not that of hot-pressed samples. Data from Raman spectroscopy and SEM/EDXS showed the appearance of Ti- and Mn-based impurities near the indentation print, in particular on fractured grains. The addition of chromia improves hardness, but does not affect toughness which is, on the other hand, greatly influenced by materials\u2019 residual porosity

Novel experimental methodologies to reconcile large- and small-signal responses of Hafnium-based Ferroelectric Tunnel Junctions

Ferroelectric Tunnel Junctions (FTJs) are promising electron devices which can be operated as memristors able to realize artificial synapses for neuromorphic computing. In this work, after a thorough validation of the in-house-developed experimental setup, novel methodologies are devised and employed to investigate the large- and small-signal responses of FTJs, whose discrepancies have proven difficult to interpret in previous literature. Our findings convey a significant insight into the contribution of the irreversible polarization switching to the bias-dependent differential capacitance of the ferroelectric–dielectric stack

Versatile experimental setup for FTJ characterization

Ferroelectric Tunnel Junctions (FTJ) are intriguing electron devices which can be operated as memristors and artificial synapses for hardware neural networks. In this work, two virtual–grounded amplifiers have been designed to extract the hysteretic I–V and Q–V characteristics directly, and good agreement between repeated measurements on both circuits demonstrates the accuracy and flexibility of the two setups. Optimal measurement conditions have also been assessed and, finally, wake–up, fatigue, and the preset–dependent early breakdown have been studied

Whole-body glucose oxidation rate during prolonged exercise in type 1 diabetic patients under usual life conditions

Objective Fuel oxidation during exercise was studied in type 1 insulin-dependent (T1DM) patients mainly under quite constant insulin and glycemia; these protocols, however, likely do not reflect patients' usual metabolic conditions. The glucose oxidation rate (GLUox) in T1DM patients under usual life conditions was thus investigated during prolonged exercise (3-h) and its behavior was described mathematically. Materials/Methods Whole-body GLUox was determined in eight T1DM patients (4/8 M; aged 35-59 years) and eight well-matched healthy subjects. Venous blood was drawn prior to and every 30 min until the end of exercise; glycemia, insulin, cortisol, and growth hormone concentrations were determined. Oxygen consumption, carbon dioxide production, and ventilation were measured at rest and thereafter every 30 min of the exercise. To prevent hypoglycemia, patients were given fruit fudge (93% sucrose) prior to / during exercise. Results Insulin concentration and glycemia were significantly higher in patients across the entire exercise period (group effect, p < 0.001 for both). GLUox decreased significantly with increasing exercise duration (time effect, p < 0.001), but no significant difference was detected between the two groups (group effect, p = NS). GLUox, expressed as the percentage of the starting value, was described by an exponential function showing a time constant of 90 min (n = 96; mean corrected R2 = 0.666). Conclusions GLUox in T1DM patients was not significantly different from the rate observed in the control subjects. The function describing the time course of GLUox may be useful to correct an estimated GLUox for the duration of exercise and help T1DM patients avoiding exercise-induced glycemic imbalances

Bridging Large-Signal and Small-Signal Responses of Hafnium-Based Ferroelectric Tunnel Junctions

Ferroelectric Tunnel Junctions (FTJs) op- erating as memristors are promising electron devices to realize artificial synapses for neuromorphic computing. But the understanding of their operation requires an in-depth electrical characterization. In this work, an in- house validated experimental setup is employed along with novel experimental methodologies to investigate the large-signal (LS) and small-signal (AC) responses of FTJs. For the first time to our knowledge, our exper- iments and physics-based simulations, help to explain the discrepancies between LS and AC experiments reported in previous literature

DFT study of graphene doping due to metal contacts

The experimental results of Metal\u2013graphene (M\u2013G) contact resistance (RC) have been investigated in\u2013depth by means of Density Functional Theory (DFT). The simulations allowed us to build a consistent picture explaining the RC dependence on the metal contact materials employed in this work and on the applied back\u2013gate voltage. In this respect, the M\u2013G distance is paramount in determining the RC behavior

Polarization switching and AC small-signal capacitance in Ferroelectric Tunnel Junctions

We here report a joint experimental and simulation analysis for large signal P-V and AC small– signal C-V curves in ferroelectric tunnel junctions. The attempt to reproduce both experimental data sets with the same model and material parameters challenges our understanding of the underlying physics, but it also helps develop a sound background for the device design

Interplay between charge trapping and polarization switching in BEOL-compatible bilayer Ferroelectric Tunnel Junctions

We here report a joint experimental and theoretical analysis of polarization switching in ferroelectric tunnel junctions. Our results show that the injection and trapping of charge into the ferroelectric-dielectric stack has a large influence on the polarization switching. Our results are relevant to the physical understanding and to the design of the devices, and for both memory and memristor applications