High Gain Graphene Based Hot Electron Transistor with Record High Saturated Output Current Density

Abstract Hot electron transistors (HETs) represent an exciting new device for integration into semiconductor technology, holding the promise of high‐frequency electronics beyond the limits of SiGe bipolar hetero transistors. With the exploration of 2D materials such as graphene and new device architectures, hot electron transistors have the potential to revolutionize the landscape of modern electronics. This study highlights a novel hot electron transistor structure with a record output current density of 800 A cm−2 and a high current gain α, fabricated using a scalable fabrication approach. The hot electron transistor structure comprises 2D hexagonal boron nitride and graphene layers wet transferred to a germanium substrate. The combination of these materials results in exceptional performance, particularly in terms of the highly saturated output current density. The scalable fabrication scheme used to produce the hot electron transistor opens up opportunities for large‐scale manufacturing. This breakthrough in hot electron transistor technology holds promise for advanced electronic applications, offering high current capabilities in a practical and manufacturable device

Coupling Genetic and Chemical Microbiome Profiling Reveals Heterogeneity of Archaeome and Bacteriome in Subsurface Biofilms That Are Dominated by the Same Archaeal Species

Earth harbors an enormous portion of subsurface microbial life, whose microbiome flux across geographical locations remains mainly unexplored due to difficult access to samples. Here, we investigated the microbiome relatedness of subsurface biofilms of two sulfidic springs in southeast Germany that have similar physical and chemical parameters and are fed by one deep groundwater current. Due to their unique hydrogeological setting these springs provide accessible windows to subsurface biofilms dominated by the same uncultivated archaeal species, called SM1 Euryarchaeon. Comparative analysis of infrared imaging spectra emonstrated great variations in archaeal membrane composition between biofilms of the two springs, suggesting different SM1 euryarchaeal strains of the same species at both aquifer outlets. This strain variation was supported by ultrastructural and metagenomic analyses of the archaeal biofilms, which included intergenic spacer region sequencing of the rRNA gene operon. At 16S rRNA gene level, PhyloChip G3 DNA microarray detected similar biofilm communities for archaea, but site-specific communities for bacteria. Both biofilms showed an enrichment of different deltaproteobacterial operational taxonomic units, whose families were, however, congruent as were their lipid spectra. Consequently, the function of the major proportion of the bacteriome appeared to be conserved across the geographic locations studied, which was confirmed by dsrB-directed quantitative PCR. Consequently, microbiome differences of these subsurface biofilms exist at subtle nuances for archaea (strain level variation) and at higher taxonomic levels for predominant bacteria without a substantial perturbation in bacteriome function. The results of this communication provide deep insight into the dynamics of subsurface microbial life and warrant its future investigation with regard to metabolic and genomic analyses

Detailed community profiling using PhyloChip G3 and SR-FTIR.

<p>A: Ordination analysis of PhyloChip G3 data based on weighted UniFrac measure of eOTU abundances followed by non-metric multidimensional scaling (NMDS). Stress for NMDS of archaeal eOTUs (#37): 0.0088. Stress for NMDS of bacterial eOTUs (#1300): 0.0223. B: Heatmap displaying significantly different families found between the two biofilm types, MSI-BF and SM-BF by PhyloChip G3 assay. Significance is based on aggregated HybScores of eOTUs on family level followed by a Welch-test. For false discovery detection please see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099801#pone.0099801.s006" target="_blank">Fig. S6</a>. C: Ordination analysis of SR-FTIR data based on a linear discriminant analysis and principal component analysis (PCA-LDA) in the spectral region of 2800–3100 cm⁻¹ on the archaea spectra extracted from the maps from the three different locations. On the right there is the plot of PCA-LDA loadings. PCA-LDA1 explains for the 93.4% of the variance, PCA-LDA2 for 5.3% and PCA-LDA3 for 0.9%. Arrows point to the infrared signals used to explain the difference between the samples: 2975 cm⁻¹, 2965 cm⁻¹, 2924 cm⁻¹ and 2850 cm⁻¹. D: PCA-LDA in the spectral regions of 900–1280 cm⁻¹ and 2800–3100 cm⁻¹ on SR-FTIR spectra of the bacteria “pixels” from the chemical maps of the samples at the three different locations. On the right there is a plot of PCA-LDA loadings in the two spectral region of interest. PCA-LDA1 explains for the 54.5% of the variance, PCA-LDA2 for 28.6% and PCA-LDA3 for 7.3%. Arrows point to the main infrared signals used to explain the difference between the samples: 2958 cm⁻¹, 2925 cm⁻¹, 2870 cm⁻¹ and 2850 cm⁻¹, in the second panel 1250 cm⁻¹, 1110 cm⁻¹, 1080 cm⁻¹ and 1045 cm⁻¹.</p

Scanning and transmission electron micrographs of biofilms, cells and hami.

<p>Left panels: MSI, right panel: SM. A: Scanning electron micrograph of MSI biofilm, showing SM1 euryarchaeal cells with defined distances and cell-cell connections. Bar: 1 µm. B: Scanning electron micrograph of SM biofilm, showing SM1 euryarchaeal cells with defined distances and fine-structured cell-cell connections. In-between: Bacterial filamentous and rod-shaped cells. Bar: 1 µm. C: Scanning electron micrograph of dividing SM1 euryarchaeal cell (MSI) with cell surface appendages. Bar: 200 nm. D: Scanning electron micrograph of dividing SM1 euryarchaeal cell (SM) with cell surface appendages. Bar: 200 nm. E: Transmission electron micrograph of cell surface appendages (hami) of SM1 euryarchaeal cells from the MSI biofilm. The hami carry the nano-grappling hooks, but besides that appear bare (square), without prickles (Moissl et al 2005). Bar: 100 nm. F: Transmission electron micrograph of cell surface appendages and matrix of SM1 euryarchaeal cells from the SM biofilm. The hami reveal the typical ultrastructure, with nano-grappling hooks and barbwire-like prickle region (square, Moissl et al 2005). Bar: 100 nm.</p

Quantification of archaeal and bacterial signatures via qPCR, FISH and SR-FTIR (values in brackes give standard deviation).

<p>*data from Probst et al., 2013.</p><p>ND: Not Determined.</p

The conversion of biofilm to string-of-pearls community in the spring water originating from the subsurface.

<p>A: Biofilm. B: Intermediate transition state. C: String-of-pearls community. Row 1: Schematic drawings. Orange: SM1 euryarchaeal cocci, Green: Filamentous, sulfide-oxidizing bacteria. Row 2: Photographs and scanning electron micrograph (2B) of different stages. Row 3: FISH images of different stages (for MSI samples please see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099801#pone.0099801-Probst1" target="_blank">[15]</a>; Archaea orange (CY3), Bacteria green (RG)). A: SM-BF, showing high dominance of Archaea. B: Attachment of archaea to filamentous bacteria. C: String-of-pearls communities with large archaeal colony and bacterial mantle. Arrows point to archaeal microcolonies, manteled by filamentous bacteria. It is proposed that attachment of SM1 Euryarchaeota to filamentous bacteria (B) mediates the transition from biofilm (A) to the string-of-pearls community (C). Scale bars: A3: 10 µm, B2: 1 µm B3: 10 mm, C3: 25 µm.</p

Scanning electron micrograph of filamentous bacterium and surrounded and cocooned by the SM1 euryarchaeal cells (SM-BF).

<p>Bar: 1 µm.</p

Measurement of charged jet cross section in pp collisions at √s = 5.02 TeV

The cross section of jets reconstructed from charged particles is measured in the transverse momentum range of 5<pT<100 GeV/c in pp collisions at the center-of-mass energy of s√=5.02 TeV with the ALICE detector. The jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, and 0.6 in the pseudorapidity range |η|<0.9−R. The charged jet cross sections are compared with the leading order (LO) and to next-to-leading order (NLO) perturbative Quantum ChromoDynamics (pQCD) calculations. It was found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters were also measured. These ratios increase from low pT to high pT and saturate at high pT, indicating that jet collimation is larger at high pT than at low pT. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb−Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC