The mitotic spindle protein CKAP2 potently increases formation and stability of microtubules

Cells increase microtubule dynamics to make large rearrangements to their microtubule cytoskeleton during cell division. Changes in microtubule dynamics are essential for the formation and function of the mitotic spindle, and misregulation can lead to aneuploidy and cancer. Using in vitro reconstitution assays we show that the mitotic spindle protein Cytoskeleton-Associated Protein 2 (CKAP2) has a strong effect on nucleation of microtubules by lowering the critical tubulin concentration 100-fold. CKAP2 increases the apparent rate constant ka of microtubule growth by 50-fold and increases microtubule growth rates. In addition, CKAP2 strongly suppresses catastrophes. Our results identify CKAP2 as the most potent microtubule growth factor to date. These finding help explain CKAP2's role as an important spindle protein, proliferation marker, and oncogene.

Bi3O4Br nanoplates as an efficient piezo-photocatalyst for organic dye degradation

The layered Bi3O4Br nanoplates were synthesized through a simple calcination process, which can simultaneously harvest visible light and ultrasonic vibration to realize the effective piezo-photocatalysis. The piezo-photocatalysis over the Bi3O4Br leads to a great enhancement in catalytic efficiency with respect to the pure photocatalysis or piezocatalysis. The apparent rate constant of piezo-photocatalysis for the degradation of MO achieves to be 0.008 min[Formula: see text], which is 5.20 and 1.51 times as high as the individual piezocatalysis and photocatalysis, respectively. This enhancement would be attributed to the built-in piezoelectric field induced by ultrasonic vibration facilitating the separation of charge carriers in photoexcited Bi3O4Br.

Room-Temperature Polyol Synthesis of Ag/SiO2 Nanocomposite as a Catalyst for 4-Nitrophenol Reduction

We prepared silver nanoparticles (AgNP) embedded in SiO2 using a green polyol approach by conducting the synthesis at ambient temperature and pH. Glycerol solutions of SiO2 and silver nitrate were stirred overnight at room temperature. UV-vis spectra and TEM images of the reaction dispersion and XRD patterns of the centrifuged solid confirmed formation of AgNP (6 ± 2 nm) were embedded in SiO2. AAS showed that, about 50% of initial silver was deposited on SiO2. The presence of SiO2 enhanced the formation of AgNP and the stability of Ag/SiO2 in glycerol. The reason for these findings was probably the ultrasonic-probe dispersion of SiO2 in glycerol, which caused chemical interactions between glycerol and SiO2. Compared to bare AgNP, the AgNP/SiO2 demonstrated higher catalytic activity toward 4-nitrophenol reduction by NaBH4. The highest apparent rate constant was approximately 1.1 ∗ 10−4 s−1, comparable with Ag/SiO2 catalysts prepared using other methods. This study proposes a greener polyol method to synthesize SiO2-supported AgNP catalyst that does not require heating or regulating pH of the reaction mixture. This nanocomposite can be used in catalytic, antimicrobial, sensing, and other applications that are using AgNP/SiO2 synthesized by conventional methods.

Facile Synthesis of g-C3N4/TiO2/Hectorite Z-Scheme Composite and Its Visible Photocatalytic Degradation of Rhodamine B

A novel g-C3N4/TiO2/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti3+ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C3N4/TiO2/hectorite was 0.01705 min−1, which is approximately 5.38 and 4.88 times that of P25 and g-C3N4, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e−) and holes(h+). The F element from Hectorite causes the formation of Vo and Ti3+ in TiO2, making it responsive to visible light. The effective separation of e− and h+ mainly results from Z-scheme transfer of photo-produced electrons in g-C3N4/TiO2 interface. The composites can be easily recycled and the degradation rate of the RhB still reached 84% after five cycles, indicating its good reusability.

Visible Light Activity in Phenol Degradation of C60@P25 Photocatalyst with Core–Shell Structure

C60@P25 photocatalyst with core–shell structure was synthesized by adsorption methods. Under visible light irradiation, the electrons of the excited C60 (C*60) adsorbed on the surface of P25can be injected into the conduction band of the P25. The electrons could combine with O2 easily, which promotes the formation of hydroxyl radicals which contributes to the dramatic visible light activity of C60@P25 photocatalyst in phenol degradation. The apparent rate constant of C60@P25 photocatalyst in phenol degradation is almost 3.3 times of which of P25. At the same time, the phenol can be mineralized completely. Under UV irradiation, the photogenerated electrons on the conduction band of P25 can be injected into the LUMO orbit of C60, which is too low that electrons could not combine with O2 easily, interdicting the formation of hydroxyl radicals, resulting in the decrease of photoactivity and weakening in the mineralization of phenol.

Water does not catalyze the reaction of OH radicals with ethanol

H2O2 as an OH precursor in simulation chambers induces an increase in the apparent rate constant with an increase in the humidity.

Thermolysis Synthesis of MoS2 Microrods for Noble Metal-Free Catalytic Reduction of 4-Nitrophenol

MoS2 microrods constructed by ultrathin nanosheets have been synthesized, for the first time, by thermal decomposition of intermediate (NH4)2MoS4 crystals, which could not only provide the single-source for both the molybdenum and sulfur atoms, but also served as the self-sacrificed template. The well-defined microstructure was characterized by XRD, SEM, TEM, XPS, BET, respectively. The results indicated that MoS2 microrods with uniform morphology were assembled by defective ultrathin nanosheets. Moreover, these MoS2 microrods exhibit superior catalytic activity with the apparent rate constant (κapp) of 0.161 min−1 for the reduction of 4-nitrophenol (4-NP) by NaBH4. Encouragingly, the MoS2 microrods still show evident activity for the reduction of 4-NP after five cycle tests, which has significant importance for the application in the reduction of 4-NP to p-aminophenol (4-AP). Also, this method can be extended to construct other kinds of metal dichalcogenides (TMDs).

Degradation of α-terpineol in aqueous solution by UV/H2O2: kinetics, transformation products and pathways

The monoterpene alcohol α-terpineol is extensively used as the foaming agent in mineral processing and can be released to environment along with the wastewater. This study evaluated the feasibility of eliminating α-terpineol in water by ultraviolet irradiation (UV) in combination with hydrogen peroxide (H2O2). Within an H2O2 dose of 10 mg/L and an UV fluence of 64.8 J/cm2, more than 95% of the α-terpineol can be removed. The reactions fitted well to pseudo-first-order kinetics, and the apparent rate constant was 0.0678 min−1. The effects of matrix species including various anions and humic acid (HA), were evaluated. The degradation rate decreased significantly with the addition of bicarbonate and HA. Further verification was carried out with three types of real water samples. In the ground water and the surface water, the degradation rate decreased likely due to the presence of natural organic matter. Finally, possible degradation pathways were proposed based on the identification of transformation products, and the occurrence of two main transformation products were monitored. This study demonstrated that the UV/H2O2 is an effective technology for the degradation of α-terpineol in water.

Production of free radicals by the Co2+/Oxone system to carry out diclofenac degradation in aqueous medium

This paper reports the degradation of a solution of 0.314 mM diclofenac (DCF), while using 5–15 mM Oxone as oxidizing agent with the catalytic action of 0.05–0.2 mM Co2+. The best performance was obtained for 10 mM Oxone and 0.2 mM Co2+, achieving the total DCF abatement and 77% removal of chemical oxygen demand after 30 min. Oxidizing of sulfate () and hydroxyl (•OH) radicals was formed by the Co2+/Oxone system. Oxone was firstly oxidized to persulfate ion that was then quickly converted into the above free radicals. For Oxone contents ≥10 mM, the decay of DCF concentration followed a second-order kinetic reaction, but the apparent rate constant changed with the Co2+ concentration used. High-performance liquid chromatography (HPLC) analysis of treated solutions showed the formation of some intermediates, whereas oxalic acid was identified as the prevalent final short-linear carboxylic acid by ion-exclusion HPLC.

Coassembly of SecYEG and SecA Fully Restores the Properties of the Native Translocon

ABSTRACTIn all cells, a highly conserved channel transports proteins across membranes. InEscherichia coli, that channel is SecYEG. Many investigations of this protein complex have used purified SecYEG reconstituted into proteoliposomes. How faithfully do activities of reconstituted systems reflect the properties of SecYEG in the native membrane environment? We investigated by comparing threein vitrosystems: the native membrane environment of inner membrane vesicles and two methods of reconstitution. One method was the widely used reconstitution of SecYEG alone into lipid bilayers. The other was our method of coassembly of SecYEG with SecA, the ATPase of the translocase. For nine different precursor species we assessed parameters that characterize translocation: maximal amplitude of competent precursor translocated, coupling of energy to transfer, and apparent rate constant. In addition, we investigated translocation in the presence and absence of chaperone SecB. For all nine precursors, SecYEG coassembled with SecA was as active as SecYEG in native membrane for each of the parameters studied. Effects of SecB on transport of precursors faithfully mimicked observations madein vivo. From investigation of the nine different precursors, we conclude that the apparent rate constant, which reflects the step that limits the rate of translocation, is dependent on interactions with the translocon of portions of the precursors other than the leader. In addition, in some cases the rate-limiting step is altered by the presence of SecB. Candidates for the rate-limiting step that are consistent with our data are discussed.IMPORTANCEThis work presents a comprehensive quantification of the parameters of transport by the Sec general secretory system in the threein vitrosystems. The standard reconstitution used by most investigators can be enhanced to yield six times as many active translocons simply by adding SecA to SecYEG during reconstitution. This robust system faithfully reflects the properties of translocation in native membrane vesicles. We have expanded the number of precursors studied to nine. This has allowed us to conclude that the rate constant for translocation varies with precursor species.