Ultrasonic Cavitation-Assisted and Acid-Activated Transcytosis of Liposomes for Universal Active Tumor Penetration

Active tumor penetration has been recently recognized as a promising strategy to resolve the limitation of nanomedicine in terms of tumor penetration, but it is challenging to develop active transporting nanocarriers. Here, an ultrasonic cavitation-assisted and acid-activatable active transporting liposome for a broad range of tumors is reported. The active transporting liposome (size and charge dual-conversional gemcitabine prodrug-integrated liposomal nanodroplet (SCGLN)) overcomes the tight blood vessel walls with the aid of ultrasonic cavitation. The SCGLN subsequently transforms from micro-size to nano-size under prolonged ultrasound radiation. Once in the acidic tumor microenvironment, the nanosized SCGLN undergoes negative-to-positive charge-reversal and triggers the cationization-initiated transcytosis to penetrate deep into tumor parenchyma. The gemcitabine-loaded SCGLN exhibits potent antitumor activity in multiple poorly permeable tumor models, which completely erases subcutaneous U251 glioma and stops the progression of orthotopic BxPC3 pancreatic ductal adenocarcinoma. This study presents a promising and universal strategy to develop active penetrating nanomedicines for efficient drug delivery in the low permeable tumor.     

PCN-Fe(III)-PTX nanoparticles for MRI guided high efficiency chemo-photodynamic therapy in pancreatic cancer through alleviating tumor hypoxia

As nanomedicine-based clinical strategies have continued to develop, the possibility of combining chemotherapy and singlet oxygen-dependent photodynamic therapy (PDT) to treat pancreatic cancer (PaC) has emerged as a viable therapeutic modality. The efficacy of such an approach, however, is likely to be constrained by the mechanisms of drug release and tumor oxygen levels. In the present study, we developed an Fe(III)-complexed porous coordination network (PCN) which we then used to encapsulate PTX (PCN-Fe(III)-PTX) nanoparticles (NPs) in order to treat PaC via a combination of chemotherapy and PDT. The resultant NPs were able to release drug in response to both laser irradiation and pH changes to promote drug accumulation within tumors. Furthermore, through a Fe(III)-based Fenton-like reaction these NPs were able to convert H₂O₂ in the tumor site to O₂, thereby regulating local hypoxic conditions and enhancing the efficacy of PDT approaches. Also these NPs were suitable for use as a T₁-MRI weighted contrast agent, making them viable for monitoring therapeutic efficacy upon treatment. Our results in both cell line and animal models of PaC suggest that these NPs represent an ideal agent for mediating effective MRI-guided chemotherapy-PDT, giving them great promise for the clinical treatment of PaC.

     

SUS430不锈钢纳米表层的高温氧化行为

通过高能喷丸方法在SUS430不锈钢表面制备纳米表层,利用X射线衍射(XRD)、热分析(TGA)、扫描电镜(SEM)及能谱(EDS)进行测试,研究了纳米表层在不同气氛中的高温氧化行为,并分析了表面自身纳米化对SUS430不锈钢耐氧化性能的影响。结果表明:纳米表层在氧化初期氧化强烈,呈线性规律迅速增重,但达到钝化的时间短,氧化膜薄且致密,厚度仅为原始表面氧化膜的1/4,使钝化以后的氧化速率比原始表面低,总的氧化增重仅为原始表面的1/3,耐氧化性大大提高。其原因是表面自身纳米化处理增加了表层的晶界面积,提高了氧化物的形核几率,也为元素的扩散提供了更多通道,因而促进了Cr元素的选择性氧化。在最表层形成的是疏松的富Fe氧化物,该层氧化物对耐氧化性的提高贡献不大,在靠近基体的底层形成致密的富Cr氧化物,能很好地抵抗基体的进一步氧化;纳米表层比原始表面更容易形成连续的氧化膜,该氧化膜的内应力小,韧性好,与基体的结合力强。     

往复式压缩机气阀弹性元件设计研究

以压缩机气阀为研究对象,提出了压缩机气阀弹性元件设计原则,总结出优良弹性元件的设计方法,以提高压缩机气阀运行的经济性和可靠性。     

循环压缩机气阀能量损失研究

通过对压缩机气阀能量损失的研究，得出循环压缩机气阀相对压力损失与相对功率损失的关系式；并通过实例故障验证，进而得出循环压缩机气阀设计的重中之重是减小阀隙阻力损失。