Effect of chloramphenicol on bacterial endosymbiotes in a strain of Amoeba proteus

The effect of chloramphenicol (CAP) on the bacterial endosymbiotes of a strain of Amoeba proteus was studied by growing the symbiotic amebae in media containing 0.5-1.6 mg/ml CAP for up to 4 weeks. Treatments with CAP caused such ultrastructural changes as expansion of the nuclear zone and deformation of symbiotes. The CAP treatment also damaged the mitochondria, e.g. disappearance of central and protrusion of peripheral cristae. Number of bacteria per ameba decreased to less than 10% of control in CAP-containing media, but no viable amebae became completely free of symbiotes. The results supported previous studies that amebae were dependent on endosymbiotes.     

Hydrogel nanoparticles with covalently linked coomassie blue for brain tumor delineation visible to the surgeon

Delineation of tumor margins is a critical and challenging objective during brain cancer surgery. A tumor-targeting deep-blue nanoparticle-based visible contrast agent is described, which, for the first time, offers in vivo tumor-specific visible color staining. This technology thus enables color-guided tumor resection in real time, with no need for extra equipment or special lighting conditions. The visual contrast agent consists of polyacrylamide nanoparticles covalently linked to Coomassie Blue molecules (for nonleachable blue color contrast), which are surface-conjugated with polyethylene glycol and F3 peptides for efficient in vivo circulation and tumor targeting, respectively.     

Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones

Cinnamate polymers are well known photoreactive polymers due to [2+2] cycloaddition reaction of cinnamate side group. In this work, we have found that the cinnamate side groups could be also reacted by thermal energy, and this reaction is presumed to attribute to the radical reaction of carbon double bond in the cinnamate groups. Contrary to the photocycloaddition reaction of the cinnamate side groups, the thermal reaction of cinnamate side group was closely related to the flexibility of polymer backbone. The difference of the mechanism between the photocycloaddition reaction and thermal crosslinking reaction was confirmed by ¹H NMR and ¹³C NMR analysis of the model compound.     

Comparison of two high temperature treatment methods on preparing electrically conductive polysulfide/Ag composites for aerospace sealant applications

High electrical conductivity of aircraft fuel tank sealant is vital to prevent charge accumulation during operation. In this work, we prepare highly conductive polysulfide (PS)/Ag composite (10⁶ S m⁻¹) via two thermal treatment methods-namely post cure annealing and high temperature (HT) curing, where the room temperature (RT) cured sample was previously found insulative. The HT cure samples resulted in a milder hardness increase compared to the RT cure-annealed ones. Through various chemical and thermal analyses, a strong coordination of the sulfide components on Ag surfaces is found blocking the electron tunneling pathways at RT, which turns out to be weakened at HT. Post cure annealing causes the decomposition of the coordinated segments and provides intimate contact of Ag particles to support conductivity. HT cure on the other hand prevents the Ag/S coordination in the first place, therefore producing highly conductive PS/Ag composite with softness well maintained which makes it the preferred method for conductive sealant applications.     

Discovery of a Potent and Selective JNK3 Inhibitor with Neuroprotective Effect Against Amyloid β-Induced Neurotoxicity in Primary Rat Neurons

As members of the MAPK family, c-Jun-N-terminal kinases (JNKs) regulate the biological processes of apoptosis. In particular, the isoform JNK3 is expressed explicitly in the brain at high levels and is involved in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). In this study, we prepared a series of five 6-dihydroxy-1H-benzo[d]imidazoles as JNK3 inhibitors and found them have potential as neuroprotective agents. Following a previous lead scaffold, benzimidazole moiety was modified with various aryl groups and hydroxylation, and the resulting compounds exhibited JNK3 inhibitory activity with improved potency and selectivity. Out of 37 analogues synthesized, (S)-cyclopropyl(3-((4-(2-(2,3-dihydrobenzo[b][1,4]dioxin -6-yl)-5,6-dihydroxy-1H-benzo[d]imidazol-1-yl)pyrimidin-2-yl)amino) piperidin-1-yl)methanone (35b) demonstrated the highest JNK3 inhibition (IC₅₀ = 9.7 nM), as well as neuroprotective effects against Aβ-induced neuronal cell death. As a protein kinase inhibitor, it also showed excellent selectivity over other protein kinases including isoforms JNK1 (>1000 fold) and JNK2 (−10 fold).     

MEMS-actuated photonic crystal switches

A compact guided-wave optical switch is realized by integrating one-dimensional photonic crystals with microelectromechanical systems (MEMS) actuators. The ON-OFF switching is achieved by physically moving a photonic crystal defect. Experimental results show an extinction ratio of 11 dB at 1.56-/spl mu/m wavelength and a 0.5-ms time constant of the step response.     

用助磨剂强化铝土矿选择性磨矿研究

分析了铝土矿矿物的晶体结构特征,论述了铝硅分离的可能性。考察了磨矿过程中助磨剂对铝土矿含铝矿物和含硅矿物磨矿效率和铝硅比的影响,筛选了4种对提高磨矿效率作用明显的助磨剂。本研究采用100mm×150mm的球磨机,在相同的磨矿条件下,加入助磨剂DA、DC-40、Z-16和六偏磷酸钠后,与不加药剂相比,磨矿产品中-200目含量分别提高了7.88、7.54、7.47、7.37个百分点,磨矿产品中铝硅比大于9的物料产率分别提高了24.62、23.17、24.17、10.14个百分点,对应的最佳添加量分别为0.5%、1%、0.5%、0.12%。结合铝土矿的晶体结构和矿浆流变性质对助磨剂的作用机理进行了分析。     

Induction of the cell cycle arrest and apoptosis by flavonoids isolated from Korean Citrus aurantium L. in non-small-cell lung cancer cells

This study investigated the anti-proliferative and apoptotic effect of flavonoids isolated from Korean Citrus aurantium L. using A549 lung cancer cells. Flavonoids potently inhibited of A549 cells in a dose-dependent manner, whereas flavonoids had a weak inhibitory effect on proliferation of WI-38 cells. Flow cytometry and Western blot analysis showed that flavonoids induced cell cycle arrest at the G2/M checkpoint by controlling the proteins expression level of cyclin B1, cdc2, cdc25c and p21^WAF1/CIP1. Also, flavonoids induced apoptosis through the regulation of the expression of caspases, cleaved PARP and Bax/Bcl-xL ratio. The activity of caspase-3 on A549 cells increased in a dose-dependent manner. These results clearly indicated that the anti-cancer effect of flavonoids on A549 cells follows multiple cellular pathways through G2/M arrest and the induction of apoptosis.     

Growth inhibition of osteosarcoma cell MG-63 by a mixture of trans,trans conjugated linoleic acid isomers: possible mechanistic actions

ABSTRACT:  The growth inhibitory effect of a mixture of t,t conjugated linoleic acid isomers ( t,t CLA) was investigated in the human osteosarcoma cell MG-63, with references to c 9, t 11 and t 10, c 12 CLA isomers. The t,t CLA effectively induced a cytotoxic effect in a time-dependent (0 to 6 d) and concentration-dependent (0 to 40 μM) manner, as compared to the reference and control treatments. The apoptosis and cell cycle related parameters were measured on the cells treated with 40 μM t,t CLA for 4 d. Flow cytometric analysis revealed that the t,t CLA treatment effectively increased the proportion of apoptotic cells with a low DNA content (sub G0/G1) and a marked loss of cells from the G0/G1 phase of the cell cycle, relative to other treatments. The occurrence of the characteristic morphological changes and DNA fragmentation confirmed the apoptosis. The level of Bax protein was increased, whereas the Bcl-2 expression was reduced. In addition, cytochrome c was released from the mitochondria into the cytosol, and the activation of caspase-3 led to the cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, the composition of linoleic and arachidonic acids in membrane was decreased by increase in t,t CLA. These findings suggest that t,t CLA incorporation in membrane activates a mitochondria-mediated apoptosis pathway that can enhance the antiproliferative effect of t,t CLA in the osteosarcoma cells.     

尼尔基水电站发电机转子总装

尼尔基水电站发电机转子为圆盘式焊接结构,由中心体和7个扇形外环组件组成,在安装间组焊或整体,介绍了转子支架焊接、配刨副立筋、磁轭替片等技术和工艺,技术方案切实可行,质量控制体系严密,转子装配工作得以保质保量地顺利完成,为机组的并网发电、安全运行创造了有利条件。