18F-Labeled GRPR Agonists and Antagonists: A Comparative Study in Prostate Cancer Imaging

Radiolabeled bombesin analogs are promising probes for cancer imaging of gastrin-releasing peptide receptor (GRPR). In this study, we developed 18F-labeled GRPR agonists and antagonists for positron emission tomography (PET) imaging of prostate cancer. GRPR antagonists ATBBN (D-Phe-Gln-Trp-Ala-Val-Gly-His-Leu-NHCH2CH3) and MATBBN (Gly-Gly-Gly-Arg-Asp-Asn-D-Phe-Gln-Trp-Ala-Val-Gly-His-Leu-NHCH2CH3), and agonists AGBBN (Gln-Trp-Ala-Val-Gly-His-Leu-MetNH2) and MAGBBN (Gly-Gly-Gly-Arg-Asp-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-MetNH2) were radiolabeled with 18F via 4-nitrophenyl 2-18F-fluoropropionate. The in vitro receptor binding, cell uptake, and efflux properties of the radiotracers were studied on PC-3 cells. An in vivo PET study was performed on mice bearing PC-3 tumors. Direct 18F-labeling of known GRPR antagonist ATBBN and agonist AGBBN did not result in good tumor targeting or appropriate pharmacokinetics. Modification was made by introducing a highly hydrophilic linker Gly-Gly-Gly-Arg-Asp-Asn. Higher receptor binding affinity, much higher cell uptake and slower washout were observed for the agonist 18F-FP-MAGBBN over the antagonist 18F-FP-MATBBN. Both tracers showed good tumor/background contrast, with the agonist 18F-FP-MAGBBN having significantly higher tumor uptake than the antagonist 18F-FP-MATBBN (P < 0.01). In conclusion, Gly-Gly-Gly-Arg-Asp-Asn linker significantly improved the pharmacokinetics of the otherwise hydrophobic BBN radiotracers. 18F-labeled BBN peptide agonists may be the probes of choice for prostate cancer imaging due to their relatively high tumor uptake and retention as compared with the antagonist counterparts

A sheep pangenome reveals the spectrum of structural variations and their effects on tail phenotypes

Structural variations (SVs) are a major contributor to genetic diversity and phenotypic variations, but their prevalence and functions in domestic animals are largely unexplored. Here we generated high-quality genome assemblies for 15 individuals from genetically diverse sheep breeds using Pacific Biosciences (PacBio) high-fidelity sequencing, discovering 130.3 Mb nonreference sequences, from which 588 genes were annotated. A total of 149,158 biallelic insertions/deletions, 6531 divergent alleles, and 14,707 multiallelic variations with precise breakpoints were discovered. The SV spectrum is characterized by an excess of derived insertions compared to deletions (94,422 vs. 33,571), suggesting recent active LINE expansions in sheep. Nearly half of the SVs display low to moderate linkage disequilibrium with surrounding single-nucleotide polymorphisms (SNPs) and most SVs cannot be tagged by SNP probes from the widely used ovine 50K SNP chip. We identified 865 population-stratified SVs including 122 SVs possibly derived in the domestication process among 690 individuals from sheep breeds worldwide. A novel 168-bp insertion in the 5' untranslated region (5' UTR) of HOXB13 is found at high frequency in long-tailed sheep. Further genome-wide association study and gene expression analyses suggest that this mutation is causative for the long-tail trait. In summary, we have developed a panel of high-quality de novo assemblies and present a catalog of structural variations in sheep. Our data capture abundant candidate functional variations that were previously unexplored and provide a fundamental resource for understanding trait biology in sheep

Effective Passivation of AlGaN/GaN HEMTs by ALD-Grown AlN Thin Film

An effective passivation technique for AlGaN/GaN high-electron-mobility transistors (HEMTs) is presented. This technique features an AlN thin film grown by plasma-enhanced atomic layer deposition (PEALD). With in situ remote plasma pretreatments prior to the AlN deposition, an atomically sharp interface between ALD-AlN and III-nitride has been obtained. Significant current collapse suppression and dynamic ON-resistance reduction are demonstrated in the ALD-AlN-passivated AlGaN/GaN HEMTs under high-drain-bias switching conditions

GaN-to-Si vertical conduction mechanisms in AlGaN/GaN-on-Si lateral heterojunction FET structures

The GaN-to-Si vertical conduction mechanisms on a low resistivity p-type (111) Si substrate under high-voltage operation are investigated using the temperature-dependent high-voltage C-V characterization and device simulation. It is found the deep depletion and weak inversion in Si will result in a high electric field at the GaN/Si interface and induce the impact ionization of Si. The generated electrons will be injected into GaN buffer layer, fill in buffer traps and act as free carriers in GaN, eventually leading to considerable vertical leakage in the AlGaN/GaN-on-Si structures. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

High Acid Biochar-Based Solid Acid Catalyst from Corn Stalk for Lignin Hydrothermal Degradation

Solid acid catalysts generally show the disadvantage of low acid amount and low recycling rate. To solve these problems, corn stalk-based solid acid catalysts were synthesized through carbonization and sulfonation processes in this work. The results showed that besides the rod-like structure inherited from raw corn stalk, the catalysts contained some small broken pieces on the surface, and the specific surface area varied from 1120 to 1640 m2/g. The functional groups (-SO3H) were successfully introduced onto the surface of the obtained solid acid catalysts. The acid amount varied between 1.2 and 2.4 mmol/g, which was higher than most of solid acid catalysts. The catalyst produced at 800 &deg;C for 6 h in carbonation and then at 150 &deg;C for 8 h in sulfonation had larger specific surface area and more sulfonate groups. In the degradation of lignin, the use of catalyst led to the generation of more aromatic compounds (65.6 wt. %) compared to that without using the catalyst (40.5 wt. %). In addition, a stable yield of reaction (85%) was obtained after four reuses. Therefore, corn stalk is suitable for high-value utilization to prepare high-acid amount biochar-based catalyst

Numerical simulation for the heat transfer behavior of oil pipeline during the shutdown and restart process

Mathematical models for the heat transfer behavior of the oil pipeline during shutdown and restart are established. And the finite difference and finite volume method are used to disperse the mathematical models to investigate the heat transfer characteristics of the thermal system. Five simulation cases are executed to obtain some findings. During restart, the pipeline can be divided into three regions with each region has a certain temperature changing trait. And the increasing of temperature on certain position has two stages and each stage has a different temperature evolution due to the movement of remain cold oil and entering of hot oil. The surrounding soil has the analogical temperature evolution in contrast to the crude oil except some thermal hysteresis exists. And a thermal influence region is also found around the pipeline. The influence of restart flow and temperature on the oil pipeline is also investigated. There is a worthy of note that in case that the restart flow is lower than a certain value, there may be appears a period of time that the oil temperature continues to decrease although the pipeline has been restarted. This condition increases the risk of oil gelatinization. Keywords: Oil pipeline, Heat transfer characteristics, Numerical simulation, Shutdown and restar

Mechanism of PEALD-Grown AlN Passivation for AlGaN/GaN HEMTs: Compensation of Interface Traps by Polarization Charges

The physical mechanism of passivation of AlGaN/GaN HEMTs by AlN thin film prepared with plasma-enhanced atomic layer deposition (PEALD) is investigated by characterizing Ni-Al2O3/AlN-GaN/AlGaN/GaN metal-insulator-semiconductor (MIS) diodes. The dielectric stack Al2O3/AlN (13/2 nm) exhibits similar capability in suppressing the current collapse in AlGaN/GaN HEMTs as the 4-nm PEALD-AlN thin film used in our previous work but delivers much lower vertical leakage to facilitate the capacitance-voltage characterizations. Exceptionally large negative bias (< -8 V) is required to deplete the 2-D electron gas in the MIS diode's C-V measurement. By virtue of quasi-static C-V characterization, it is revealed that positive fixed charges of similar to 3.2 x 10(13) e/cm(2) are introduced by the PEALD-AlN. The positive fixed charges are suggested to be polarization charges in the monocrystal-like PEALD-AlN. They can effectively compensate the high-density slow-response acceptor-like interface traps, resulting in effective suppression of current collapse

Controlling J-Aggregate Formation For Increased Short-Circuit Current And Power Conversion Efficiency With A Squaraine Donor

A squaraine dye is tested for novel application in a near-infrared-active organic photovoltaic cell that is subsequently optimized to obtain a power conversion efficiency of 2.4 ± 0.3%. The optimization utilizes an Alq3 buffer layer and macroscopic structure control through the addition of co-solvents in the spin-casting process. Co-solvent addition increases the amount of aggregates present as measured through linear absorption spectroscopy, and there is a concurrent increase in both efficiency and short-circuit current. An interpretation of the greatly increased current density is presented that describes how increased J-aggregation likely increases hole mobility and, as a result, charge separation of the photogenerated excited state. Copyright © 2012 John Wiley & Sons, Ltd. Macroscopic control of solution conditions prior to spin-coating allows for effective nanoscale control of donor morphology. This morphology has been optimized to give efficiency and short-circuit gains in a bulk heterojunction solar cell. © 2014 John Wiley & Sons, Ltd

A Novel and Effective Recyclable BiOCl/BiOBr Photocatalysis for Lignin Removal from Pre-Hydrolysis Liquor

The presence of lignin hampers the utilization of hemicelluloses in the pre-hydrolysis liquor (PHL) from the kraft-based dissolving pulp production process. In this paper, a novel process for removing lignin from PHL was proposed by effectively recycling catalysts of BiOCl/BiOBr. During the whole process, BiOCl and BiOBr were not only adsorbents for removing lignin, but also photocatalysts for degrading lignin. The results showed that BiOCl and BiOBr treatments caused 36.3% and 33.9% lignin removal, respectively, at the optimized conditions, and the losses of hemicellulose-derived saccharides (HDS) were both 0.1%. The catalysts could be regenerated by simple photocatalytic treatment and obtain considerable CO and CO2. After 15 h of illumination, 49.9 μmol CO and 553.0 μmol CO2 were produced by BiOCl, and 38.7 μmol CO and 484.3 μmol CO2 were produced by BiOBr. Therefore, both BiOCl and BiOBr exhibit excellent adsorption and photocatalytic properties for lignin removal from pre-hydrolysis