A Temperature Analysis of High-power AlGaN/GaN HEMTs

Galliumnitride has become a strategic superior material for space, defense and civil applications, primarily for power amplification at RF and mm-wave frequencies. For AlGaN/GaN high electron mobility transistors (HEMT), an outstanding performance combined together with low cost and high flexibility can be obtained using a System-in-a-Package (SIP) approach. Since thermal management is extremely important for these high power applications, a hybrid integration of the HEMT onto an AlN carrier substrate is proposed. In this study we investigate the temperature performance for AlGaN/GaN HEMTs integrated onto AlN using flip-chip mounting. Therefore, we use thermal simulations in combination with experimental results using micro-Raman spectroscopy and electrical dc-analysis.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Micro-cooler Enhancements by Barrier Interface Analysis

Peer reviewedPublisher PD

Terahertz oscillations in an In_0.53Ga_0.47As submicron planar gunn diode

The length of the transit region of a Gunn diode determines the natural frequency at which it operates in fundamental mode – the shorter the device, the higher the frequency of operation. The long-held view on Gunn diode design is that for a functioning device the minimum length of the transit region is about 1.5μm, limiting the devices to fundamental mode operation at frequencies of roughly 60 GHz. Study of these devices by more advanced Monte Carlo techniques that simulate the ballistic transport and electron-phonon interactions that govern device behaviour, offers a new lower bound of 0.5μm, which is already being approached by the experimental evidence that has shown planar and vertical devices exhibiting Gunn operation at 600nm and 700nm, respectively. The paper presents results of the first ever THz submicron planar Gunn diode fabricated in In<sub>0.53</sub>Ga<sub>0.47</sub>A on an InP substrate, operating at a fundamental frequency above 300 GHz. Experimentally measured rf power of 28 µW was obtained from a 600 nm long ×120 µm wide device. At this new length, operation in fundamental mode at much higher frequencies becomes possible – the Monte Carlo model used predicts power output at frequencies over 300 GHz

Comparing CAR and TCR engineered T cell performance as a function of tumor cell exposure

Chimeric antigen receptor (CAR) T cell therapies have resulted in profound clinical responses in the treatment of CD19-positive hematological malignancies, but a significant proportion of patients do not respond or relapse eventually. As an alternative to CAR T cells, T cells can be engineered to express a tumor-targeting T cell receptor (TCR). Due to HLA restriction of TCRs, CARs have emerged as a preferred treatment moiety when targeting surface antigens, despite the fact that functional differences between engineered TCR (eTCR) T and CAR T cells remain ill-defined. Here, we compared the activity of CAR T cells versus engineered TCR T cells in targeting the B cell malignancy-associated antigen CD20 as a function of antigen exposure. We found CAR T cells to be more potent effector cells, producing higher levels of cytokines and killing more efficiently than eTCR T cells in a short time frame. However, we revealed that the increase of antigen exposure significantly impaired CAR T cell expansion, a phenotype defined by high expression of coinhibitory molecules and effector differentiation. In contrast, eTCR T cells expanded better than CAR T cells under high antigenic pressure, with lower expression of coinhibitory molecules and maintenance of an early differentiation phenotype, and comparable clearance of tumor cells

The 2018 GaN Power Electronics Roadmap

Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here

Prophylactic, preemptive, and curative treatment for sinusoidal obstruction syndrome/veno-occlusive disease in adult patients : a position statement from an international expert group

Sinusoidal obstruction syndrome, also known as veno-occlusive disease (SOS/VOD), is a potentially life-threatening complication that can develop after hematopoietic cell transplantation (HCT). While SOS/VOD may resolve within a few weeks in the majority of patients with mild-to-moderate disease, the most severe forms result in multiorgan dysfunction and are associated with a high mortality rate (>80%). Therefore, careful surveillance may allow early detection of SOS/VOD, particularly as the licensed available drug is proven to be effective and reduce mortality. The aim of this work is to propose an international consensus guideline for the treatment and prevention of SOS/VOD in adult patients, on behalf of an international expert group.Peer reviewe

Apoptosis in cancer: from pathogenesis to treatment

Apoptosis is an ordered and orchestrated cellular process that occurs in physiological and pathological conditions. It is also one of the most studied topics among cell biologists. An understanding of the underlying mechanism of apoptosis is important as it plays a pivotal role in the pathogenesis of many diseases. In some, the problem is due to too much apoptosis, such as in the case of degenerative diseases while in others, too little apoptosis is the culprit. Cancer is one of the scenarios where too little apoptosis occurs, resulting in malignant cells that will not die. The mechanism of apoptosis is complex and involves many pathways. Defects can occur at any point along these pathways, leading to malignant transformation of the affected cells, tumour metastasis and resistance to anticancer drugs. Despite being the cause of problem, apoptosis plays an important role in the treatment of cancer as it is a popular target of many treatment strategies. The abundance of literature suggests that targeting apoptosis in cancer is feasible. However, many troubling questions arise with the use of new drugs or treatment strategies that are designed to enhance apoptosis and critical tests must be passed before they can be used safely in human subjects