Tailored Tolane-Perfluorotolane Assembly as Supramolecular Base Pair Replacement in DNA

Arene-fluoroarene interactions offer outstanding possibilities for engineering of supramolecular systems, including nucleic acids. Here, we implement the tolane-perfluorotolane interaction as base pair replacement in DNA. Tolane (THH) and perfluorotolane (TFF) moieties were connected to acyclic backbone units, comprising glycol nucleic acid (GNA) or butyl nucleic acid (BuNA) building blocks, that were incorporated via phosphoramidite chemistry at opposite positions in a DNA duplex. Thermodynamic analyses by UV thermal melting revealed a compelling stabilization by THH/TFF heteropairs only when connected to the BuNA backbone, but not with the shorter GNA linker. Detailed NMR studies confirmed the preference of the BuNA backbone for enhanced polar π-stacking. This work defines how orthogonal supramolecular interactions can be tailored by small constitutional changes in the DNA backbone, and it inspires future studies of arene-fluoroarene-programmed assembly of DNA.     

Crystal Structure of an i-Motif from the HRAS Oncogene Promoter

An i-motif is a non-canonical DNA structure implicated in gene regulation and linked to cancers. The C-rich strand of the HRAS oncogene, 5′-CGCCC GTGCCC TGCGCCC GCAACCC GA-3′ (herein referred to as iHRAS), forms an i-motif in vitro but its exact structure was unknown. HRAS is a member of the RAS proto-oncogene family. About 19 % of US cancer patients carry mutations in RAS genes. We solved the structure of iHRAS at 1.77 Å resolution. The structure reveals that iHRAS folds into a double hairpin. The two double hairpins associate in an antiparallel fashion, forming an i-motif dimer capped by two loops on each end and linked by a connecting region. Six C−C⁺ base pairs form each i-motif core, and the core regions are extended by a G−G base pair and a cytosine stacking. Extensive canonical and non-canonical base pairing and stacking stabilizes the connecting region and loops. The iHRAS structure is the first atomic resolution structure of an i-motif from a human oncogene. This structure sheds light on i-motifs folding and function in the cell.     

一种基于BCD工艺的宽压-宽温电流基准电路

设计了一种基于BCD工艺的宽压-宽温电流基准电路.利用片上多晶硅电阻的温度系数受工艺影响较小的特点,选定其为基准电流定义单元.分析片上电阻温度特性,并设计与其温度系数相等的参考电压,加载到电阻上,从而实现了温度系数很低的基准电流.分析了高温下三极管寄生元件漏电现象,通过添加补偿管,提高了基准电流在高温下的稳定性.电流基...     

Schiff Base Reaction in a Living Cell: In Situ Synthesis of a Hollow Covalent Organic Polymer To Regulate Biological Functions

Artificially performing chemical reactions in living biosystems to attain various physiological aims remains an intriguing but very challenging task. In this study, the Schiff base reaction was conducted in cells using Sc(OTf)₃ as a catalyst, enabling the in situ synthesis of a hollow covalent organic polymer (HCOP) without external stimuli. The reversible Schiff base reaction mediated intracellular Oswald ripening endows the HCOP with a spherical, hollow porous structure and a large specific surface area. The intracellularly generated HCOP reduced cellular motility by restraining actin polymerization, which consequently induced mitochondrial deactivation, apoptosis, and necroptosis. The presented intracellular synthesis system inspired by the Schiff base reaction has strong potential to regulate cell fate and biological functions, opening up a new strategic possibility for intervening in cellular behavior.     

发射极空气桥InGaP/GaAs HBT的DC和RF特性分析

为抑制电流增益崩塌,提高HBT的热稳定性,研制了发射极空气桥互连结构的HBT晶体管,应用ICCAP提取参数建立VBIC模型,结合模型参数对三种不同结构HBT的DC和RF特性进行比较分析.与引线爬坡互连结构相比,发射极空气桥互连结构HBT的热阻得到改善,热稳定性提高;与发射极电阻镇流方式相比,发射极空气桥HBT的截止频率(fT)相同,最大振荡频率(fmax)提高,最大稳定功率增益(MSG)高出约5dB.     

Engineering Nucleotidoproteins for Base-Pairing-Assisted Cytosolic Delivery and Genome Editing

Protein therapeutics targeting intracellular machineries hold profound potential for disease treatment, and hence robust cytosolic protein delivery technologies are imperatively demanded. Inspired by the super-negatively charged, nucleotide-enriched structure of nucleic acids, adenylated pro-proteins (A-proteins) with dramatically enhanced negative surface charges have been engineered for the first time via facile green synthesis. Then, thymidine-modified polyethyleneimine is developed, which exhibits strong electrostatic attraction, complementary base pairing, and hydrophobic interaction with A-proteins to form salt-resistant nanocomplexes with robust cytosolic delivery efficiencies. The acidic endolysosomal environment enables traceless restoration of the A-proteins and consequently promotes the intracellular release of the native proteins. This strategy shows high efficiency and universality for a variety of proteins with different molecular weights and isoelectric points in mammalian cells. Moreover, it enables highly efficient delivery of CRISPR-Cas9 ribonucleoproteins targeting fusion oncogene EWSR1-FLI1, leading to pronounced anti-tumor efficacy against Ewing sarcoma. This study provides a potent and versatile platform for cytosolic protein delivery and gene editing, and may benefit the development of protein pharmaceuticals.     

Palladium-Catalyzed Inverse and Normal Dehydrogenative Aza-Morita–Baylis–Hillman Reactions with γ,δ-Unsaturated Compounds

σ-Lewis base-catalyzed regio- and enantioselective aza-Morita–Baylis–Hillman (MBH) reaction of α,β,γ,δ-unsaturated systems remains a challenge due to the intrinsic covalent activation mode. Here we demonstrate that a Pd⁰ complex can mediate the dehydrogenative reaction of γ,δ-unsaturated compounds to give corresponding electron-poor dienes, which further undergo δ-regioselective umpolung Friedel–Crafts-type addition to imines via auto-tandem Pd⁰-π-Lewis base catalysis. After β-H elimination of in situ formed Pd^II-complexes, unprecedented and chemically inverse aza-MBH-type adducts are finally furnished with fair to outstanding enantioselectivity, and a diversity of functional groups and both ketimine and aldimine acceptors can be well tolerated. Moreover, switchable α-regioselective normal aza-MBH-type reaction also can be realized by tuning catalytic conditions, whereas moderate to good enantioselectivity with low to excellent Z/E-selectivity is attained.     

BiCMOS结构中阱特性的研究

叙述了以双极型工艺为主体的ＢｉＣＭＯＳ结构中ｐ阱电阻比值非线性的特性及其与芯片合格率的关系。在ｐ阱下面采用埋层，抑制或消除了ＢｉＣＯＭＳ中；ｐ阱结构的寄生效应，从而提高了芯片合格率。     

2.5D硅转接板关键电参数测试技术研究

硅转接板是3D IC中实现高密度集成的关键模块,获取其技术参数对微系统的设计至关重要.以实际研制的一种2.5D硅转接板为研究对象,对大马士革铜布线(Cu-RDL)、硅通孔(TSV)关键电参数的测试结构与测试方法进行了研究,并对TSV电参数测试结构的寄生电容进行了分析.研究结果表明,研制的2.5D硅转接板中10 μm×8...