Structure‐Invertible Nanoparticles for Triggered Co‐Delivery of Nucleic Acids and Hydrophobic Drugs for Combination Cancer Therapy

Here, a new type of structure‐invertible, redox‐responsive polymeric nanoparticle for the efficient co‐delivery of nucleic acids and hydrophobic drugs in vitro and in vivo is reported for the first time, to combat the major challenges facing combination cancer therapy. The co‐delivery vector, which is prepared by conjugating branched poly(ethylene glycol) with dendrimers of two generations (G2) through disulfide linkages, is able to complex nucleic acids and load hydrophobic drugs with high loading capacity through structure inversion. The cleavage of disulfide linkages at intracellular glutathione‐rich reduction environment significantly decreases the cytotoxicity, and promotes more efficient drug release and gene transfection in vitro and in vivo. The co‐delivery carrier also displays enhanced endosomal escape capability and improved serum stability in vitro as compared with G2, and exhibits prolonged residence time and stronger transfection activity in vivo. Most importantly, co‐delivery of doxorubicin (DOX) and B‐cell lymphoma 2 (Bcl‐2) small interfering RNA (siRNA) exerts a combinational effect against tumor growth in murine tumor models in vivo, which is much more effective than either DOX or Bcl‐2 siRNA‐based monotherapy. The structure‐invertible nanoparticles may constitute a promising stimuli‐responsive system for the efficacious co‐delivery of multiple cargoes in future clinical applications of combination cancer therapies.     

The Role of Heteroatoms Leading to Hydrogen Bonds in View of Extended Chemical Stability of Organic Semiconductors

The major challenge in organic electronics concerns the stability of organic semiconductor materials which affects the operational lifetime of devices. Recent reports have shown that hydrogen‐bonded pigments of the indigoid family are air‐ and moisture resistant. The magenta pigment quinacridone, a hydrogen‐bonded molecule in the solid state with a pentacene like frame, is a perfect example for extraordinary chemical stability. Here, studies using in situ spectroscopic methods comparing quinacridone and pentacene are presented. A different spectral response of their radical cations is observed upon chemical doping. While in pentacene the barrier between doping and irreversible overoxidation is small, this stability toward overoxidation is increased by the heteroatomic structure, leading to hydrogen‐bonded quinacridone. This work provides insight into molecular design principles that may lead to next‐generation organic semiconductors with enhanced stability and performance.     

H_2-Fe~(3+)/Fe~(2+)氧化还原液流电池初步研究

提出一种新型氧化还原液流电池:H2-Fe3+/Fe2+氧化还原液流电池。系统研究了Fe3+/Fe2+电对于未处理与热处理聚丙烯腈基石墨毡上的电化学性能及两种石墨毡组装电池充放电性能。实验结果表明:经热处理之后,石墨毡电化学反应活性面积变大,Fe3+/Fe2+电荷传递阻抗降低,从而降低了电池极化。以热处理石墨毡为电池正极,碳纸为负极组成电池,在50 m A/cm2充放电时,电压效率为87.43%,与用未处理石墨毡组装电池相比,电压效率提高11.82%,内阻降低50%。     

全钒液流电池建模及充放电双闭环控制

介绍了全钒液流电池的工作特性,并依据全钒液流电池和DC/DC双向变换器的电路模型建立数学函数模型,采用充放电的双闭环控制,利用Matlab/Simulink进行了电池充放电的仿真。结果验证了全钒液流电池双闭环充放电控制的可行性和优越性。全钒液流电池在大型光伏储能系统中具有广泛的应用前景,针对其进行充放电控制研究是非常有必要的。     

Radical cations of amino acids and peptides: Structures and stabilities

Amino acid and peptide radical cations, M ^{. +}, are formed by oxidative dissociations of [Cu(auxiliary ligand)(M)] ^{. 2+} and [Metal^III(salen)(M)]⁺ complexes. The most easily formed radicals contain either an aromatic or basic amino acid residue. Aromatic amino acids have low ionization energies, are easily oxidized and delocalize the charge and spin over the ring systems; basic amino acids facilitate formation of α‐radicals that have captodative structures in which the charge and spin are formally separated, although feeding back some of the charge onto the amide or carboxyl group adjacent to the radical center through hydrogen bonding enriches the electron‐withdrawing properties and is highly stabilizing. DFT calculations located five isomers of His ^{. +} with an α‐radical with a captodative structure at the global minimum in a deep potential well. An IRMPD spectrum confirmed that this isomer is the experimentally observed “long‐lived” isomer. When both charge and spin are on the peptide backbone, as in [GGG] ^{. +}, captodative structures have the lowest energies; the barriers to interconversion between the three isomeric α‐radicals of [GGG] ^{. +} are high as the charge impedes migration of a hydrogen atom. Dissociation of [GGG] ^{. +} is charge‐driven. In peptide radical cations containing a basic amino acid residue the charge is sequestered on the side chain and the radical center, either on the backbone or on another side chain, initiates the fragmentation. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:655–671, 2009     

Parametric study of the factors influencing simultaneous denitrification and enhanced biological phosphorus removal

In this study, the effect of various factors such as C:N ratio, carbon source, percentage P content in the sludge influencing the simultaneous denitrification and enhanced biological phosphorus removal was investigated in batch tests on bean and tomato waste sludge from an upflow anaerobic sludge blanket reactor–anoxic/aerobic system and municipal sludge from a circulating fluidized bed bioreactor. A correlation between the change in redox potential and rate of P release was developed. Interestingly, maximum P release was observed at positive redox potential in some of the batch tests. Simultaneous denitrification and P release under anoxic conditions was observed during all the batch tests. Sludge acclimatization improved the efficiency of the sludge and proved independency of maximum specific denitrification rate and P content of sludges. The contribution of denitrifying PAOs to anoxic P uptake was determined through the denitrification control test at an initial level of PO₄‐P of 100–120 mg dm^?3. Copyright © 2006 Society of Chemical Industry     

Nation膜对多硫化钠／溴电池性能的影响

在单电池中用充电一放电循环测试方法研究了不同厚度Nation膜对多硫化钠／溴单电池效率及电池负极液中的多硫（Sx＋1^2-）及硫氢根离子（HS^-）向正极溶液中扩散（即透硫率）的影响。结果表明：随着膜厚度的增加，电池的库仑效率升高，膜的透硫率及电压效率降低。用四丁基溴化胺（TBAB）对Nation112膜进行了初步改性处理，显著提高了电池的库仑效率，减少了膜的透硫率，但由于改性膜电阻的增加，致使电池电压效率下降。     

Removal of H2S using a new Ce(IV) redox mediator by a mediated electrochemical oxidation process

BACKGROUND: Hydrogen sulfide (H₂S) from industrial activities and anaerobic manure decomposition in commercial livestock animal operations is an offensive malodorous and toxic gas even in small concentrations, causing serious discomfort and health and social problems. The objective of this study was to employ for the first time a novel, attractive, low cost, environmentally benign mediated electrochemical oxidation (MEO) process with Ce(IV) as the redox catalyst for H₂S gas removal from an H₂S–air feed mixture. RESULTS: The influence of liquid flow rate (Q_L) from 2–4 L min^?1, gas flow rate (Q_G) from 30–70 L min^?1, H₂S concentration in the H₂S–air feed mixture from 5–15 ppm, and Ce(III) pre‐mediator concentration in the electrochemical cell from 0.1–1 mol L^?1 on H₂S removal efficiency were investigated. Both liquid and gas flow rates influenced the removal efficiencies, but in opposite directions. Nearly 98% H₂S removal was achieved when the concentration of Ce(IV) mediator ion in the flowing scrubbing liquid reached 0.08 mol L^?1. CONCLUSIONS: The new MEO method proved promising for H₂S removal, achieving high removal efficiency. Integration of the electrochemical cell with the scrubber set‐up ensured continuous regeneration of the mediator and its repeated reuse for H₂S removal, avoiding use of additional chemicals. Since the process works at room temperature and atmospheric pressure utilizing conventional transition metal oxide electrodes more commonly used in industrial applications, it is also safe and economical. Copyright © 2008 Society of Chemical Industry