Effect of the clinical course of acute-on-chronic liver failure prior to liver transplantation on post-transplant survival

BACKGROUND & AIMS: Patients with acute-on-chronic liver failure (ACLF) can be listed for liver transplantation (LT) because LT is the only curative treatment option. We evaluated whether the clinical course of ACLF, particularly ACLF-3, between the time of listing and LT affects 1-year post-transplant survival. METHODS: We identified patients from the United Network for Organ Sharing database who were transplanted within 28 days of listing and categorized them by ACLF grade at waitlist registration and LT, according to the EASL-CLIF definition. RESULTS: A total of 3,636 patients listed with ACLF-3 underwent LT within 28 days. Among those transplanted, 892 (24.5%) recovered to no ACLF or ACLF grade 1 or 2 (ACLF 0–2) and 2,744 (75.5%) had ACLF-3 at transplantation. One-year survival was 82.0% among those transplanted with ACLF-3 vs. 88.2% among those improving to ACLF 0–2 (p 60 years of age, 1-year survival was significantly higher among those who improved from ACLF-3 to ACLF 0–2 than among those who did not. CONCLUSIONS: Improvement from ACLF-3 at listing to ACLF 0–2 at transplantation enhances post-LT survival, particularly in those who recovered from circulatory or brain failure, or were removed from the mechanical ventilator. The beneficial effect of improved ACLF on post-LT survival was also observed among patients >60 years of age. LAY SUMMARY: Liver transplantation (LT) for patients with acute-on-chronic liver failure grade 3 (ACLF-3) significantly improves survival, but 1-year survival probability after LT remains lower than the expected outcomes for transplant centers. Our study reveals that among patients transplanted within 28 days of waitlist registration, improvement of ACLF-3 at listing to a lower grade of ACLF at transplantation significantly enhances post-transplant survival, even among patients aged 60 years or older. Subgroup analysis further demonstrates that improvement in circulatory failure, brain failure, or removal from mechanical ventilation have the strongest impact on post-transplant survival

Optoelectronics with electrically tunable PN diodes in a monolayer dichalcogenide

One of the most fundamental devices for electronics and optoelectronics is the PN junction, which provides the functional element of diodes, bipolar transistors, photodetectors, LEDs, and solar cells, among many other devices. In conventional PN junctions, the adjacent p- and n-type regions of a semiconductor are formed by chemical doping. Materials with ambipolar conductance, however, allow for PN junctions to be configured and modified by electrostatic gating. This electrical control enables a single device to have multiple functionalities. Here we report ambipolar monolayer WSe2 devices in which two local gates are used to define a PN junction exclusively within the sheet of WSe2. With these electrically tunable PN junctions, we demonstrate both PN and NP diodes with ideality factors better than 2. Under excitation with light, the diodes show photodetection responsivity of 210 mA/W and photovoltaic power generation with a peak external quantum efficiency of 0.2%, promising numbers for a nearly transparent monolayer sheet in a lateral device geometry. Finally, we demonstrate a light-emitting diode based on monolayer WSe2. These devices provide a fundamental building block for ubiquitous, ultra-thin, flexible, and nearly transparent optoelectronic and electronic applications based on ambipolar dichalcogenide materials.Comment: 14 pages, 4 figure

Electrically Tunable Excitonic Light Emitting Diodes based on Monolayer WSe2 p-n Junctions

Light-emitting diodes are of importance for lighting, displays, optical interconnects, logic and sensors. Hence the development of new systems that allow improvements in their efficiency, spectral properties, compactness and integrability could have significant ramifications. Monolayer transition metal dichalcogenides have recently emerged as interesting candidates for optoelectronic applications due to their unique optical properties. Electroluminescence has already been observed from monolayer MoS2 devices. However, the electroluminescence efficiency was low and the linewidth broad due both to the poor optical quality of MoS2 and to ineffective contacts. Here, we report electroluminescence from lateral p-n junctions in monolayer WSe2 induced electrostatically using a thin boron nitride support as a dielectric layer with multiple metal gates beneath. This structure allows effective injection of electrons and holes, and combined with the high optical quality of WSe2 it yields bright electroluminescence with 1000 times smaller injection current and 10 times smaller linewidth than in MoS2. Furthermore, by increasing the injection bias we can tune the electroluminescence between regimes of impurity-bound, charged, and neutral excitons. This system has the required ingredients for new kinds of optoelectronic devices such as spin- and valley-polarized light-emitting diodes, on-chip lasers, and two-dimensional electro-optic modulators.Comment: 13 pages main text with 4 figures + 4 pages upplemental material

Longterm Outcomes of Patients Undergoing Liver Transplantation for Acute-on-Chronic Liver Failure

AIMS: Recent data have demonstrated greater than 80% one-year survival probability after liver transplantation (LT) for patients with severe acute on chronic liver failure (ACLF). However, long term outcomes and complications are still unknown for this population. Our aim was to compare long-term patient and graft survival among patients transplanted across all grades of ACLF. METHODS: We analyzed the UNOS database, years 2004-2017. Patients with ACLF were identified using the EASL-CLIF criteria. Kaplan-Meier and Cox regression methods were used to determine patient and graft survival and associated predictors of mortality in adjusted models. RESULTS: A total of 75,844 patients were transplanted of which 48,854 (64.4%) had no ACLF, 9,337 (12.3%) had ACLF-1, 9,386 (12.4%) had ACLF-2 and 8,267 (10.9%) had ACLF-3. Patients transplanted without ACLF had a greater proportion of hepatocellular carcinoma within (23.8%) and outside (12.7%) Milan criteria. Five-year patient survival after LT was lower in the ACLF-3 patients compared with the other groups (67.7%, p<0.001), although after year 1, the percentage decrease in survival was similar among all groups. Infection was the primary cause of death among all patient groups in the first year. After the first year, infection was the main cause of death in patients transplanted with ACLF-1 (31.1%), ACLF-2 (33.3%) and ACLF-3 (36.7%), whereas malignancy was the predominant cause of death in those transplanted with no ACLF (38.5%). Graft survival probability at 5 years was above 90% among all patient groups. CONCLUSION: Patients transplanted with ACLF-3 have lower 5-year survival as compared to ACLF 0-2 but mortality rates were not significantly different after the first year following LT. Graft survival was excellent across all ACLF groups

Plasma-Enhanced Atomic Layer Deposition of Al<inf>2</inf>O<inf>3</inf> on Graphene Using Monolayer hBN as Interfacial Layer

Abstract: The deposition of dielectric materials on graphene is one of the bottlenecks for unlocking the potential of graphene in electronic applications. The plasma enhanced atomic layer deposition of 10 nm thin high quality aluminum oxide (Al2O3) on graphene is demonstrated using a monolayer of hexagonal boron nitride (hBN) as protection layer. Raman spectroscopy is performed to analyze possible structural changes of the graphene lattice caused by the plasma deposition. The results show that a monolayer of hBN in combination with an optimized deposition process can effectively protect graphene from damage, while significant damage is observed without an hBN layer. Electrical characterization of double gated graphene field effect devices confirms that the graphene does not degrade during the plasma deposition of Al2O3. The leakage current densities are consistently below 1 pA µm−2 for electric fields across the insulators of up to 8 MV cm−1, with irreversible breakdown happening above. Such breakdown electric fields are typical for Al2O3 and can be seen as an indicator for high quality dielectric films

A fitness assay for comparing RNAi effects across multiple C. elegans genotypes

<p>Abstract</p> <p>Background</p> <p>RNAi technology by feeding of <it>E. coli </it>containing dsRNA in <it>C. elegans </it>has significantly contributed to further our understanding of many different fields, including genetics, molecular biology, developmental biology and functional genomics. Most of this research has been carried out in a single genotype or genetic background. However, RNAi effects in one genotype do not reveal the allelic effects that segregate in natural populations and contribute to phenotypic variation.</p> <p>Results</p> <p>Here we present a method that allows for rapidly comparing RNAi effects among diverse genotypes at an improved high throughput rate. It is based on assessing the fitness of a population of worms by measuring the rate at which <it>E. coli </it>is consumed. Critically, we demonstrate the analytical power of this method by QTL mapping the loss of RNAi sensitivity (in the germline) in a recombinant inbred population derived from a cross between Bristol and a natural isolate from Hawaii. Hawaii has lost RNAi sensitivity in the germline. We found that polymorphisms in <it>ppw-1 </it>contribute to this loss of RNAi sensitivity, but that other loci are also likely to be important.</p> <p>Conclusions</p> <p>In summary, we have established a fast method that improves the throughput of RNAi in liquid, that generates quantitative data, that is easy to implement in most laboratories, and importantly that enables QTL mapping using RNAi.</p

Ultrafast electronic read-out of diamond NV centers coupled to graphene

Nonradiative transfer processes are often regarded as loss channels for an optical emitter1, since they are inherently difficult to be experimentally accessed. Recently, it has been shown that emitters, such as fluorophores and nitrogen vacancy centers in diamond, can exhibit a strong nonradiative energy transfer to graphene. So far, the energy of the transferred electronic excitations has been considered to be lost within the electron bath of the graphene. Here, we demonstrate that the trans-ferred excitations can be read-out by detecting corresponding currents with picosecond time resolution. We electrically detect the spin of nitrogen vacancy centers in diamond electronically and con-trol the nonradiative transfer to graphene by electron spin resonance. Our results open the avenue for incorporating nitrogen vacancy centers as spin qubits into ultrafast electronic circuits and for harvesting non-radiative transfer processes electronically

Light-emitting diodes by band-structure engineering in van der Waals heterostructures

The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals.The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative di�erential resistance tunnelling transistors photovoltaic devices and so on. Here, we take the complexity and functionality of such van der Waals heterostructures to the next level by introducing quantum wells (QWs) engineered with one atomic plane precision. We describe light-emitting diodes (LEDs) made by stacking metallic graphene, insulating hexagonal boron nitride and various semiconducting monolayers into complex but carefully designed sequences. Our first devices already exhibit an extrinsic quantum e�ciency of nearly 10% and the emission can be tuned over a wide range of frequencies by appropriately choosing and combining 2D semiconductors (monolayers of transition metal dichalcogenides). By preparing the heterostructures on elastic and transparent substrates, we show that they can also provide the basis for flexible and semi-transparent electronics. The range of functionalities for the demonstrated heterostructures is expected to grow further on increasing the number of available 2D crystals and improving their electronic quality

Strong light-matter coupling in two-dimensional atomic crystals

Two dimensional (2D) atomic crystals of graphene, and transition metal dichalcogenides have emerged as a class of materials that show strong light-matter interaction. This interaction can be further controlled by embedding such materials into optical microcavities. When the interaction is engineered to be stronger than the dissipation of light and matter entities, one approaches the strong coupling regime resulting in the formation of half-light half-matter bosonic quasiparticles called microcavity polaritons. Here we report the evidence of strong light-matter coupling and formation of microcavity polaritons in a two dimensional atomic crystal of molybdenum disulphide (MoS2) embedded inside a dielectric microcavity at room temperature. A Rabi splitting of 46 meV and highly directional emission is observed from the MoS2 microcavity owing to the coupling between the 2D excitons and the cavity photons. Realizing strong coupling effects at room temperature in a disorder free potential landscape is central to the development of practical polaritonic circuits and switches.Comment: 25 pages, 7 figure