Most semiconductor devices are now packaged in an epoxy polymer composite, which includes silica powder filler for reducing the thermal expansion coefficient. However, increased heat output from ...near‐future semiconductors will require higher thermal conductivity fillers such as aluminum nitride (AlN) powder, instead of silica. Dispersant chemistry is applied, in order to achieve a high volume percentage of AlN powder in epoxy without causing excessive viscosity before the epoxy monomer is crosslinked, thereby increasing the thermal conductivity of the composite. In the preliminary experiment, high solids loading, up to 57 vol%, was achieved with a wide particle size distribution, and the viscosity of that dispersion was 60 000 to 90 000 cps, resulting in easy flow by gravity alone at room temperature. The highest thermal conductivity of the composites measured by the hot‐disk method was 3.39 W/mK, which is approximately 15 times higher than pure epoxy. The Agari and Uno model was a good fit to the experimental data. Electronic I–V curves obtained after encapsulation of testing devices indicated that the highly AlN‐filled epoxy slip appeared to be feasible for use in the encapsulation of integrated circuit chips.
Plant proteome analysis Cánovas, Francisco M.; Dumas-Gaudot, Eliane; Recorbet, Ghislaine ...
Proteomics (Weinheim),
February 2004, Letnik:
4, Številka:
2
Journal Article
Recenzirano
Proteome analysis is becoming a powerful tool in the functional characterization of plants. Due to the availability of vast nucleotide sequence information and based on the progress achieved in ...sensitive and rapid protein identification by mass spectrometry, proteome approaches open up new perspectives to analyze the complex functions of model plants and crop species at different levels. In this review, an overview is given on proteome studies performed to analyze whole plants or specific tissues with particular emphasis on important physiological processes such as germination. The chapter on subcellular proteome analysis of plants focuses on the progress achieved for plastids and mitochondria but also mentions the difficulties associated with membrane‐bound proteins of these organelles. Separate chapters are dedicated to the challenging analysis of woody plants and to the use of proteome approaches to investigate the interaction of plants with pathogens or with symbiotic organisms. Limitations of current techniques and recent conceptual and technological perspectives for plant proteomics are briefly discussed in the final chapter.
Homozygosity for a natural deletion variant of the HIV-coreceptor molecule CCR5, CCR5Δ32, confers resistance toward HIV infection. Allogeneic stem cell transplantation from a CCR5Δ32-homozygous donor ...has resulted in the first cure from HIV ('Berlin patient'). Based thereon, genetic disruption of CCR5 using designer nucleases was proposed as a promising HIV gene-therapy approach. Here we introduce a novel TAL-effector nuclease, CCR5-Uco-TALEN that can be efficiently delivered into T cells by mRNA electroporation, a gentle and truly transient gene-transfer technique. CCR5-Uco-TALEN mediated high-rate CCR5 knockout (>90% in PM1 and >50% in primary T cells) combined with low off-target activity, as assessed by flow cytometry, next-generation sequencing and a newly devised, very convenient gene-editing frequency digital-PCR (GEF-dPCR). GEF-dPCR facilitates simultaneous detection of wild-type and gene-edited alleles with remarkable sensitivity and accuracy as shown for the CCR5 on-target and CCR2 off-target loci. CCR5-edited cells were protected from infection with HIV-derived lentiviral vectors, but also with the wild-type CCR5-tropic HIV-1BaL strain. Long-term exposure to HIV-1BaL resulted in almost complete suppression of viral replication and selection of CCR5-gene edited T cells. In conclusion, we have developed a novel TALEN for the targeted, high-efficiency knockout of CCR5 and a useful dPCR-based gene-editing detection method.
The study of metal‐dinitrogen complexes has lent valuable insight into the nature of dinitrogen (N2) reduction to ammonia (NH3), known as “nitrogen fixation.” Even so, understanding this difficult ...transformation continues to be an elusive goal for chemists. The N2 chemistry of chromium (Cr) is exceptional for its diversity, rarity, and richness of depth. Hans Karsch opined in 1977 that “Almost all transition metals are known to form complexes with molecular nitrogen, but in the case of some metals ‐ notably chromium ‐ the examples are few and far between.” Although that sentiment hasn't changed much in 42 years, recent advances in the field of Cr‐N2 chemistry have begun to illuminate that elusive relationship. Herein we cover the theory and experimental basis for chromium's coordination, activation, reduction, and catalysis of N2 to NH3. An emphasis will be placed on work towards understanding catalytic systems for chromium mediated dinitrogen reduction.
Chromium has long been one of the most reluctant metals to coordinate dinitrogen. Historical accounts and recent developments of molecular Cr‐N2 complexes are highlighted herein. Exciting new discoveries have firmly shown Cr complexes are cabable of activating N2, and catalyzing the reduction of N2 to NH3.
Solving protein structures by single-particle cryoelectron microscopy (cryo-EM) has become a crucial tool in structural biology. While exciting progress is being made toward the visualization of ...small macromolecules, the median protein size in both eukaryotes and bacteria is still beyond the reach of cryo-EM. To overcome this problem, we implemented a platform strategy in which a small protein target was rigidly attached to a large, symmetric base via a selectable adapter. Of our seven designs, the best construct used a designed ankyrin repeat protein (DARPin) rigidly fused to tetrameric rabbit muscle aldolase through a helical linker. The DARPin retained its ability to bind its target: GFP. We solved the structure of this complex to 3.0 Å resolution overall, with 5–8 Å resolution in the GFP region. As flexibility in the DARPin position limited the overall resolution of the target, we describe strategies to rigidify this element.
Display omitted
•Exploration of constructs to display small proteins for single-particle cryo-EM•New fusion protein allows cryo-EM visualization of <100-kDa proteins, such as GFP•3-Å structure of GFP:DARPin-aldolase platform with 5 to 8 Å in GFP:DARPin region•Higher resolution of the target currently limited by DARPin position flexibility
Proteins <100 kDa are difficult to solve by single-particle cryo-EM. Here, Yao et al. explored seven constructs to display a target protein. Using GFP as a test case, they found a DARPin-aldolase fusion capable of cryo-EM visualization of the target. Flexibility in the DARPin position limited the resolution.
PDF
