甲苯在乙酸中自动氧化时钴催化作用的电化学活化

在无／有氧分子存在条件下，用电化学技术氧化了含乙酸钴（Co^2+)的乙酸中的甲苯。首先根据阳极钝化情况研究了Co^3+的生成条件。无氧时，甲苯按法拉第生产工艺被间接氧化，主要生成乙酸苄酸，乙酸苄酸再被氧化生成苯甲酸；而在有氧条件下，通过非法拉第工艺经苯甲醛生成主要为苯甲酸的产物。电化学初始生成的Co^3+抑制了自氧化的诱导期。电解条件下，加速了自氧化作用。

Protective Effects of Tea Polyphenol on Cerebral Ischemia-Reperfusion Injury in Rats and Its Scavenging Oxy-radical and Anticerebral Lipid Peroxidation Effects

AIM To study the protective effects of tea polyphenol (TP) on cerebral ischemia reperfusion injury in rats and its scavenging oxygen free radical(OFR) activities and antilipid peroxidation in vitro . METHODS Cerebral ischemia reperfusion injury was produced by bilateral ligation of the common carotid arteries with vagus nerves and reperfusion for 45 min. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. Superoxide anion (O 2) from xanthine xanthine oxidase system and hydroxyl radical (·OH) from Fe 2+ -H 2O 2 system were determined with spectrophotometry. RESULTS During Cerebral ischemia reperfusion,TP improved the activities of superoxide dismutase ( P 【0 05), GSH peroxidase( P 【0 01) and catalase( P 【0 01), while decreasing the maiondialdchyde content in the brain( P 【0 05) and brain water content ( P 【0 01). Tea polyphenol possessed significantly scavenging effects on ·OH produced by Fenton reaction and O 2 produced by xanthine xanthine oxidase system (the IC 50 were 2 2 mmol·L -1 and 1 9 mmol·L -1 respectively). Tea polyphenol could significant inhibit the lipid peroxidation of cerbral mitochondrial membrane induced by ·OH in a concentration dependent manner. CONCLUSION The results indicate that tea polyphenol could protect the injury on cerebral ischemia reperfusion in rats for OFR, these effects may be related to its scavenging effects on oxygen free radicals and antilipid peroxidant.

Hybrid intelligent PID control design for PEMFC anode system

Control design is important for proton exchange membrane fuel cell (PEMFC) generator. This work researched the anode system of a 60-kW PEMFC generator. Both anode pressure and humidity must be maintained at ideal levels during steady operation. In view of characteristics and requirements of the system, a hybrid intelligent PID controller is designed specifically based on dynamic simulation. A single neuron PI controller is used for anode humidity by adjusting the water injection to the hydrogen cell. Another incremental PID controller, based on the diagonal recurrent neural network (DRNN) dynamic identification, is used to control anode pressure to be more stable and exact by adjusting the hydrogen flow rate. This control strategy can avoid the coupling problem of the PEMFC and achieve a more adaptive ability. Simulation results showed that the control strategy can maintain both anode humidity and pressure at ideal levels regardless of variable load, nonlinear dynamic and coupling characteristics of the system. This work will give some guides for further control design and applications of the total PEMFC generator.

Mechanism study of organic antioxidant and inorganic salt on suppressing coal oxidation

The advantages and disadvantages of organic antioxidant and inorganic salt on suppressing coal oxidation were analyzed on the basis of the theory that coal oxidation mechanisms can be attributed to the free radical chain-type reaction mechanism. The inhibition curves on suppressing coal oxidation of the different type and different concentration of organic antioxidant and inorganic salt were given through experimental study and data processing. Then some conclusions can be gained from the experimental study combining with theoretical analysis. First the inhibition mechanism of the organic antioxidant and inorganic salt is different. The former is that the chemical action is the dominant position. It can be called as the chain termination theory because the free radical is captured during coal oxidation. And the later is that the physical effect is the dominant position. It can be called as the decreasing-temperature theory because the liquid membrane which was formed by the inorganic salt can make coal body be the state of wetness and prevent oxygen from coal surface. Second the inhibition effect of the organic antioxidant is higher than the inorganic salt in the later period. But it is lower in the early period.

Antioxidative Activity of Polysaccharide Fractions Isolated from Tricholoma Matsutake Sing. with Ultrafiltration

Polysaccharides of Tricholoma matsutake Sing. were extracted with boilingwater, followed by precipitating with ethanol. Two membranes of different molecular weight cut-off, namely, 30 kD and 10 kD were chosen with ultrafiltration. The antioxidant activity of the purification polysaccharides was evaluated by various antioxidant assay, including DPPH （l,l-diphenyl-2-picrylhydrazyl） radical scavenging, superoxide anion radical scavenging and hydrogen peroxide scavenging. The scavenging effect on hydroxyl radical and DPPH radical, which may be comparable to Vitamin C, while the scavenging effect on superoxide anion radicals was not obvious.

Mitochondrial dysfunction and aging muscle

Mitochondrial dysfunction in aged skeletal muscle has been mainly attributable to mtDNA deletions, uncoupling in oxidative phosphorylation, leading to ATP deficit. Moreover, the accumulation of damaged mitochondria is associated with imperfect autophagocytosis and declined biogenesis of efficient mitochondria. Mitochondria-associated apoptotic signaling is involved in the loss of fibers and atrophy of the remaining fibers by ROS, TNF-α, and denervation, leading to sarcopenia. Current investigations have indicated that exercise, especially resistance exercise, has extensively preventive effects on sarcopenia. Whether caloric restriction in aged animals is suitable for aged people remains to be further clinlically experimented. Additionally, it will be interesting to develop effectively supplementary and alternative medical methods associated with Chinese tonifying herbs to prevent or reverse sarcopenia in the future because of their efficacy and less frequent side effects.

Molecular biomarker record of paleooceanographic environment in the East China Sea during the last 35000 years

By reference of the δ18O and δ13C isotopic compositions of G.sacculifer and accelerator mass spectrometry (AMS)14C dates, the U K 37 , ∑C – 21 /∑C +- 22 and Pr/Pn in core DGKS9603 have been used to characterize the changes of paleooceanographic environment occurring in the East China Sea (ECS) during the last 35000 years. The stratigraphic records of these proxies have shown that during the last 35 ka the Okinawa Trough has gone through 7 stronger cold-climate events (C1–C7) and 9 terrigenous matter-decreasing events (e2–e9), of which, the C1 corresponds to the cold episode occurring in the middle late Holocene, C2–C4 and C7 correspond to the H1–H4 events, respectively. e1 and e3–e8 correspond to the decrease of sea surface temperature (SST), respectively. The terrigenous inputs increased when Heinrich events occurred. Climate colding resulted in the decrease of terrigenous matter transported by rivers, and the increase of that transported by winter monsoon. Heinrich events are closely related to East Asia monsoon. During the Last Glacial Maximum (LGM, 15.5–25.8 Cal ka BP), reduction environment fluctuated strongly, bringing forth three stronger reduction events (R1–R3) and one weaker reduction event (O), of which, R1–R3 correspond to the decrease of SST and increase of terrigenous nutrient and O corresponds to the decrease of terrigenous nutrient. The fluctuation of reduction condition must be related to the change of sea surface productivity.