A Novel Extraction Procedure of Contact Characteristic Parameters from Current–Voltage Curves in CdZnTe and CdTe Detectors

The estimation of the characteristic parameters of the electrical contacts in CdZnTe and CdTe detectors is related to the identification of the main transport mechanisms dominating the currents. These investigations are typically approached by modelling the current–voltage (I–V) curves with the interfacial layer–thermionic-diffusion (ITD) theory, which incorporates the thermionic emission, diffusion and interfacial layer theories into a single theory. The implementation of the ITD model in measured I–V curves is a critical procedure, requiring dedicated simplifications, several best fitting parameters and the identification of the voltage range where each transport mechanism dominates. In this work, we will present a novel method allowing through a simple procedure the estimation of some characteristic parameters of the metal–semiconductor interface in CdZnTe and CdTe detectors. The barrier height and the effects of the interfacial layer will be evaluated through the application of a new function related to the differentiation of the experimental I–V curves

Predictors of HER2 gene amplification in immunohistochemistry score 2+ Early Breast Cancer according to 2018 ASCO/CAP guidelines: a single institution analysis.

Background: HER2 overexpression occurs in approximately 15-20% of invasive breast cancers (BC). From a pathological point of view HER2 positivity is defined by intense circumferential membrane complete staining in more than 10% of tumour cells in immunohistochemistry (IHC score 3+). When complete circumferential staining is weak to moderate (IHC score 2+) double probe in situ ibridation (ISH) is mandatory to define HER2 status. In 2018 ASCO/CAP guidelines were updated to provide additional guidance in HER2 equivocal cases to allow a greater discrimination between positive and negative cases. Our aim is to find predictors of HER2 positivity among IHC score 2+ early breast cancer specimens analysed according to 2018 ASCO/CAP guidelines. Patients and methods: 253 cases of early BC diagnosed at Modena Cancer Center between November 2013 and August 2017 were identified. Stage, ISH result, hormonal receptor status (HR), proliferation index (MIB1), and histological grade were captured; menopausal status was available too. All IHC score 2+ cases were reclassified according to 2018 ASCO/CAP guidelines. The association between pathological tumour features, clinical characteristics and ISH positivity was assessed using Fisher test. Results: Overall, 25.7% IHC score 2+ BC resulted HER2 amplified in double probe ISH. High tumour grade (G3 vs G1-2) and MIB1 > 20% significantly predict HER2 ISH amplification (p=0,0001). No correlation was found according to HR, stage, or menopausal status. The majority (185; 98.4%) of HER2-ve BC were reclassified as group 5 (HER2/ CEP17 ratio <2 and HER2 copy number <4 signals/cell) except for 3 specimens classified as group 4 (HER2/CEP17 RATIO <2 and HER2 copy number \ub34 but <6 signals/cell). In HER2+ve group the majority (62; 95.3%) specimens were group 1 (HER2/CEP17 RATIO >2 and HER2 copy number =4 signals/cell), no specimen was group 2, and only 3 cases were classified as group 3 (HER2/CEP17 RATIO <2 and HER2 copy number >6 signals/cell). Conclusions: In this IHC score 2+ BC series, reclassification according to 2018 ASCO/CAP guidelines identified only 4.6% group 3 and 1.6% group 4 cases. The routinely assessment of grading and proliferation index could help to predict HER2 amplification in IHC score 2+ samples even if it must not substitute ISH assay in determining eligibility for HER2 targeted therapies

Tolerance without clonal expansion: Self-antigen-expressing B cells program self-reactive T cells for future deletion

B cells have been shown in various animal models to induce immunological tolerance leading to reduced immune responses and protection from autoimmunity. We show that interaction of B cells with naive T cells results in T cell triggering accompanied by the expression of negative costimulatory molecules such as PD-1, CTLA-4, B and T lymphocyte attenuator, and CD5. Following interaction with B cells, T cells were not induced to proliferate, in a process that was dependent on their expression of PD-1 and CTLA-4, but not CD5. In contrast, the T cells became sensitive to Ag-induced cell death. Our results demonstrate that B cells participate in the homeostasis of the immune system by ablation of conventional self-reactive T cells

Retrospective assessment of inguinal hernia repair in elderly outpatients

Background In the last ten years Day Surgery has significantly evolved, due to improvements in surgery and anaesthesia, and the need of reducing long term admission costs [1]. However, is Day Surgery suitable for elderly patients? The aim of this paper is to assess the risk of over 70 year-old outpatients who underwent inguinal hernia repair, and suggest an adequate preoperative pathway

Laser-induced transient currents in CdZnTe quasi-hemispherical radiation detector

Laser-induced transient currents were measured after applying pulsed or direct-current bias to a CdZnTe quasi-hemispherical radiation detector with gold contacts. The temporal evolution of current transients was analyzed to evaluate the dynamics of the space charge formation and its spatial distribution. The observed effects were explained by a model involving hole injection from positively biased contacts. Experimental results were complemented by numerical simulations, which supported the model. This paper discusses how the detected phenomena affect the detector performance and proposes an improved detector design

Reduced Self-Reactivity of an Autoreactive T Cell After Activation with Cross-reactive Non–Self-Ligand

Autoreactive CD4+ T lymphocytes are critical to the induction of autoimmune disease, but because of the degenerate nature of T cell receptor (TCR) activation such receptors also respond to other ligands. Interaction of autoreactive T cells with other non–self-ligands has been shown to activate and expand self-reactive cells and induce autoimmunity. To understand the effect on the autoreactivity of naive cross-reactive T cells of activation with a potent nonself ligand, we have generated a TCR transgenic mouse which expresses a TCR with a broad cross-reactivity to a number of ligands including self-antigen. The activation of naive transgenic recombination activating gene (Rag)2−/− T cells with a potent non–self-ligand did not result in a enhancement of reactivity to self, but made these T cells nonresponsive to the self-ligand and anti-CD3, although they retained a degree of responsiveness to the non–self-ligand. These desensitized cells had many characteristics of anergic T cells. Interleukin (IL)-2 production was selectively reduced compared with interferon (IFN)-γ. p21ras activity was reduced and p38 mitogen-activated protein kinase (MAPK) was relatively spared, consistent with known biochemical characteristics of anergy. Surprisingly, calcium fluxes were also affected and the anergic phenotype could not be reversed by exogenous IL-2. Therefore, activation with a hyperstimulating non–self-ligand changes functional specificity of an autoreactive T cell without altering the TCR. This mechanism may preserve the useful reactivity of peripheral T cells to foreign antigen while eliminating responses to self

Incomplete Charge Collection at Inter-Pixel Gap in Low-and High-Flux Cadmium Zinc Telluride Pixel Detectors

The success of cadmium zinc telluride (CZT) detectors in room-temperature spectroscopic X-ray imaging is now widely accepted. The most common CZT detectors are characterized by enhanced-charge transport properties of electrons, with mobility-lifetime products µeτe > 10−2 cm2/V and µhτh > 10−5 cm2/V. These materials, typically termed low-flux LF-CZT, are successfully used for thick electron-sensing detectors and in low-flux conditions. Recently, new CZT materials with hole mobility-lifetime product enhancements (µhτh > 10−4 cm2/V and µeτe > 10−3 cm2/V) have been fabricated for high-flux measurements (high-flux HF-CZT detectors). In this work, we will present the performance and charge-sharing properties of sub-millimeter CZT pixel detectors based on LF-CZT and HF-CZT crystals. Experimental results from the measurement of energy spectra after charge-sharing addition (CSA) and from 2D X-ray mapping highlight the better charge-collection properties of HF-CZT detectors near the inter-pixel gaps. The successful mitigation of the effects of incomplete charge collection after CSA was also performed through original charge-sharing correction techniques. These activities exist in the framework of international collaboration on the development of energy-resolved X-ray scanners for medical applications and non-destructive testing in the food industry

Advances in High-Energy-Resolution CdZnTe Linear Array Pixel Detectors with Fast and Low Noise Readout Electronics

Radiation detectors based on Cadmium Zinc Telluride (CZT) compounds are becoming popular solutions thanks to their high detection efficiency, room temperature operation, and to their reliability in compact detection systems for medical, astrophysical, or industrial applications. However, despite a huge effort to improve the technological process, CZT detectors’ full potential has not been completely exploited when both high spatial and energy resolution are required by the application, especially at low energies (<10 keV), limiting their application in energy-resolved photon counting (ERPC) systems. This gap can also be attributed to the lack of dedicated front-end electronics which can bring out the best in terms of detector spectroscopic performances. In this work, we present the latest results achieved in terms of energy resolution using SIRIO, a fast low-noise charge sensitive amplifier, and a linear-array pixel detector, based on boron oxide encapsulated vertical Bridgman-grown B-VB CZT crystals. The detector features a 0.25-mm pitch, a 1-mm thickness and is operated at a −700-V bias voltage. An equivalent noise charge of 39.2 el. r.m.s. (corresponding to 412 eV FWHM) was measured on the test pulser at 32 ns peaking time, leading to a raw resolution of 1.3% (782 eV FWHM) on the 59 keV line at room temperature (+20 °C) using an uncollimated 241Am, largely improving the current state of the art for CZT-based detection systems at such short peaking times, and achieving an optimum resolution of 0.97% (576 eV FWHM) at 1 µs peaking time. The measured energy resolution at the 122 keV line and with 1 µs peaking time of a 57Co raw uncollimated spectrum is 0.96% (1.17 keV). These activities are in the framework of an Italian collaboration on the development of energy-resolved X-ray scanners for material recycling, medical applications, and non-destructive testing in the food industry

High performance platinum contacts on high-flux CdZnTe detectors

The need for direct X-ray detection under high photon flux with moderate or high energies (30–100 keV range) has strongly increased with the rise of the 4th Generation Synchrotron Light Sources, characterised by extremely brilliant beamlines, and of other applications such as spectral computed tomography in medicine and non-destructive tests for industry. The novel Cadmium Zinc Telluride (CZT) developed by Redlen Technologies can be considered the reference material for high-flux applications (HF-CZT). The enhanced charge transport properties of the holes allow the mitigation of the effects of radiation induced polarization phenomena, typically observed in standard CZT materials (LF-CZT) under high photon flux. However, standard LF-CZT electrical contacts led to inacceptable high dark leakage currents on HF-CZT devices. In this work, a detailed study on the characteristics of new optimized sputtered platinum electrical contacts on HF-CZT detectors is reported. The results from electrical and spectroscopic investigations, showed the best performances on HF-CZT detectors with platinum anode, coupled with both platinum or gold cathode. The morphology, structure, and composition of Pt/CZT contact have been analysed by means of Transmission Electron Microscopy (TEM) on microscopic lamellas obtained by Focused Ion Beam (FIB), highlighting the presence of CdTeO3 oxide at the metal semiconductor interface