Correlation between plasma antioxidant capacity and verbascoside levels in rats after oral administration of lemon verbena extract

Phenylpropanoids are the main class of compounds from lemon verbena which have shown a wide biological activity, verbascoside being the most abundant one. In this work, the composition of a lemon verbena extract was elucidated by HPLC-ESI-MS/MS and one flavone and one methoxylated phenylpropanoid were found in this source for the first time. The antioxidant activity of the lemon verbena extract was fully characterised by several methodologies. Unexpectedly, the extract was especially active in lipophilic environments and lipid peroxidation inhibition assay, as it was found for pure verbascoside. The lemon verbena extract, containing verbascoside as its major bioactive compound, was acutely administered to rats and verbascoside was the only metabolite detected in plasma samples as measured by HPLC mass spectrometry. The correlation between the highest verbascoside concentration in plasma and maximum plasma antioxidant capacity was observed at 20 min as measured by different techniques, i.e. minimum malondialdehyde (MDA) generation, highest ferric-reducing ability of plasma (FRAP value) and maximum superoxide dismutase activity (SOD). Therefore, the in vitro measurements of the antioxidant activity of lemon verbena extract may significantly support the antioxidant activity observed in vivo in this work. Moreover, neither evidence of acute oral toxicity nor adverse effects were observed in mice when the lemon verbena extract containing 25% verbascoside was used at a dosage of 2000 mg/kg.     

Optical properties of polymeric materials for concentrator photovoltaic systems

As part of our research on materials for concentrator photovoltaics (CPV), we are evaluating the optical properties and solar radiation durability of a number of polymeric materials with potential in CPV applications. For optical materials in imaging or non-imaging optical systems, detailed knowledge of the wavelength-dependent complex index of refraction is important for system design and performance, yet optical properties for many polymeric systems are not available in the literature. Here we report the index of refraction, optical absorbance, haze, and Urbach edge analysis results of various polymers of interest for CPV systems. These values were derived from ellipsometry and from using a VUV-VASE and transmission based absorbance spectroscopy on thick film samples.Fluoropolymers such as poly(tetrafluoroethylene-co-hexafluoropropylene) (Teflon^® FEP), poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (Teflon^® PFA) and poly(ethylene-co-tetrafluoroethylene) (Teflon^® ETFE Film) have desirable optical and physical properties for optical applications in CPV. Ethylene backbone polymers such as polyvinylbutyral (PVB) sheet (e.g., DuPont^TM PV5200), and ethylene co-polymers such as poly(ethylene-co-vinyl acetate) (EVA) (e.g., DuPont^TM Elvax^® PV1400), and poly(ethylene-co-methacrylic acid metal salt) ionomer sheet (e.g., DuPont^TM PV5300) have applications as encapsulants in crystalline silicon (c-Si) and other flat plate PV applications. These materials are available with both a wide variety of polymer compositions and additive packages which affect their optical properties such as the UV absorption edge. Even materials such as DuPont’s Kapton^® polyimide films, which are used behind the PV cell for their electrically insulating properties, have optical requirements, and we have also characterized these materials.The detailed optical properties of these materials will be useful in the design of the geometrical optics of a CPV system and optimization of the system’s optical throughput. This information will also provide insights into the system’s optical absorption. This is important, for example in the UV, where this absorption can impact the radiation durability of the materials.     

The annealing behavior of Cu nanoparticles in Ar-ion implanted spinel

Magnesium aluminate spinel crystals (MgAl₂O₄ (1 1 0)) deposited with 30 nm Cu film on surface were implanted with 110 keV Ar-ions to a fluence of 1.0 × 10¹⁷ ions/cm² at 350 °C, and then annealed in vacuum condition at the temperature of 500, 600, 700, 800 and 900 °C for 1 h, respectively. Ultraviolet-visible spectrometry (UV-VIS), scanning electron microscopy (SEM), Rutherford backscattering (RBS) and transmission electron microscopy (TEM) were adopted to analyze the specimens. After implantation, the appearance of surface plasmon resonance (SPR) absorbance peak in the UV-VIS spectrum indicated the formation of Cu nanoparticles, and the TEM results for 500 °C also confirmed the formation of Cu nanoparticles at near-surface region. In annealing process, The SPR absorbance intensity increased at 500 and 700 °C, decreased with a blue shift of the peak position at 600 and 800 °C, and the peak disappeared at 900 °C. The SPR absorbance intensity evolution with temperature was discussed combined with other measurement results (RBS, SEM and TEM).     

血液在可见光及近红外范围内随温度变化的动态吸收特性

人体病变组织的光热效应是皮肤病激光疗法与光学诊断的基础,深入理解血液光吸收特性随温度变化的动态规律对利用激光来治疗葡萄酒色斑(PWS)等血管性疾病具有重要意义。设计并搭建了血液动态吸收光谱实验测量系统,利用常温水浴将血液样品缓慢加热至80℃(0.5～1.0℃·min^-1),每间隔5℃为单位对血液的光吸收特性进行测量,得到了血液在可见光及近红外范围400～1000 nm内随温度变化的动态吸收光谱。实验结果表明,加热过程中血液光吸收特性变化可分为4个阶段:常温至50℃血液吸收光谱基本无变化;50～58℃吸收特性曲线变平缓, 630 nm处吸光度增加为常温下的2倍;随着温度的进一步上升,血液光吸收特性大幅度增加;65℃后略有增加直至不再变化。整个加热过程中,血液吸光度均在970 nm处存在峰值,并且吸收性能随着温度的上升有所增加,这为今后使用该波段治疗较深的顽固病变血管奠定了坚实的基础。     

防腐剂与抗磨剂的竞争吸附效应

利用含有防腐剂的润滑油和轴承珠进行模拟吸附实验,通过紫外光谱的测量方法对吸附实验前后的润滑油进行吸光度测量,发现了吸附实验前后润滑油紫外吸光度的区别, 利用郎伯-贝尔原理对润滑油与轴承珠接触界面膜中的吸附量进行了计算,证实了防腐剂在摩擦副表面的吸附作用;对含有抗磨剂和防腐剂的润滑油进行吸附实验,并测量了实验前后润滑油的紫外吸光度,发现了相同防腐剂质量分数、不同抗磨剂质量分数润滑油紫外吸光度有较大区别;通过紫外光谱测量和界面膜中防腐剂吸附量的计算方法,表征了抗磨剂对防腐剂在摩擦副表面吸附量的定性影响规律 ,证实了抗磨剂与防腐剂的竞争吸附关系。     

类产碱假单胞菌对不同型号PVA的降解特性研究

对类产碱假单胞菌降解不同型号PVA(0588,1788,2088,1750,1799)的降解效果及降解特性进行了研究。采用UV2900紫外分光光度计测吸光度法测定了各型号PVA的降解率,同时研究了PVA的分子量和醇解度、PVA浓度、接种菌种浓度、摇瓶转速等对PVA降解率的影响。结果表明:醇解度一定时,高聚合度PVA的降解效率远低于低聚合度PVA;而聚合度一定时,醇解度对降解率的影响不明显。在培养温度为30℃,培养时间为72 h,摇瓶转速为180 rad/min,PVA的质量浓度为0.5 g/L,接种菌的体积分数为4.0%时,PVA的降解率可达90.15%。     

Fatty Acid Composition, Antioxidant Properties, and Antiproliferative Capacity of Selected Cold-Pressed Seed Flours

Cold-pressed seed flours from pumpkin, parsley, mullein, cardamom, and milk thistle were examined for total oil, fatty acid profile of the oil, total phenolic content (TPC), scavenging activities against peroxyl (ORAC), hydroxyl (HOSC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (RDSC) radicals, and antiproliferative capacity against HT-29 human colon cancer cells. The cold-pressed parsley seed flour contained a very high concentration of total oil—17.6 g/100 g flour—with primarily C18:1 fatty acid at 86.2 g/100 g fatty acids. All other flour oils had relatively high levels of saturated fats, ranging from 39.0 to 62.9 g/100 g fatty acids. The tested seed flours demonstrated significant TPC and free radical scavenging activities. Milk thistle seed flour had the highest TPC value of 25.2 mg gallic acid equivalent per g flour (GAE mg/g) followed by that of parsley seed flour at 8.1 GAE mg/g. Milk thistle seed-flour extract also had significantly higher antioxidant activities than all other extracts against all tested radicals. The milk thistle seed-flour extract had an ORAC value of 1131 μmol trolox equivalents (TE) per g flour (TE μmol/g), a HOSC value of 893 TE μmol/g, and an RDSC value of 61 TE μmol/g. Also, ORAC, HOSC, and TPC values were significantly correlated (P < 0.01) under the experimental conditions. The cold-pressed milk thistle seed flour inhibited the proliferation of HT-29 cancer cells in a dose-dependent manner. Results from this study suggest that these cold-pressed seed flours may serve as natural sources of antioxidants and may be used to improve human health.     

Optimization of PACl dose to reduce RO cleaning in an IMS

In order to ensure stable treated water quality and to reduce chemical costs in any treatment plant it is necessary to study and optimize the coagulant dosing control (CDC). This research focused on the affects of coagulant in the integrated membrane (UF & RO) system employed for industrial water production. The dose of coagulant (PACl) might be associated (partly) with the frequency of cleaning in the RO units, and a value of 20 abs/m in the UF permeate is the control of the dosage process. This could suggest that organic fouling is directly and indirectly (inducing biofouling as well) the cause of fouling of the RO membranes. Nevertheless, high doses of PACl could produce scaling of aluminium and, in this work minimizing PACl to prevent operational problems in RO membranes was focused.

The approach involved the study of the treatment processes, determination of the optimum dose of coagulant, evaluation of the removal efficiency of UV and DOC by coagulation. The available data, which comprised monthly/weekly measurements for a period of six years of operation, was studied and analyzed and an attempt was made to draw some conclusions for the plant regarding the coagulant dosage and the link with UV absorbance as control.

The study of the coagulant dosing control revealed that the use of simple and robust online sensors like UV measurement allows an automatic dosing control although this parameter is not found to be sufficient to fully characterize nor predict fouling during membrane operation and there is no link between UV after the UF and the cleaning frequency of the RO. Parameters, as the added value allowed to verify the doses efficiencies in UV and DOC removal. Coagulant dose depends on the level of UV absorbance in the UF permeate and it should never be higher than 20 abs/m to ensure a RO cleaning frequency as long as possible. However, it was found that the target value of 20 abs/m produced substantial over dose of coagulant — 90% of the time – when UV removal is considered only. In the same way, for coagulant doses in excess of 5 mg/L, the additional removal of UV is less than 2.5% per mg coagulant/L, which suggests that the current dose is on the high side.

Furthermore, a coagulant dose in excess of 5 mg/L did not produce significant additional UV removal, and thus a reduction from 14 mg/L (2005 dose) to ca. 7 mg/L could be considered.     

Freshwater DOM quantity and quality from a two-component model of UV absorbance

We present a model that considers UV-absorbing dissolved organic matter (DOM) to consist of two components (A and B), each with a distinct and constant spectrum. Component A absorbs UV light strongly, and is therefore presumed to possess aromatic chromophores and hydrophobic character, whereas B absorbs weakly and can be assumed hydrophilic. We parameterised the model with dissolved organic carbon concentrations [DOC] and corresponding UV spectra for c. 1700 filtered surface water samples from North America and the United Kingdom, by optimising extinction coefficients for A and B, together with a small constant concentration of non-absorbing DOM (0.80 mg DOC L⁻¹). Good unbiased predictions of [DOC] from absorbance data at 270 and 350 nm were obtained (r² = 0.98), the sum of squared residuals in [DOC] being reduced by 66% compared to a regression model fitted to absorbance at 270 nm alone. The parameterised model can use measured optical absorbance values at any pair of suitable wavelengths to calculate both [DOC] and the relative amounts of A and B in a water sample, i.e. measures of quantity and quality. Blind prediction of [DOC] was satisfactory for 9 of 11 independent data sets (181 of 213 individual samples).