228Ra in cow’s milk from an anomalous region of Pernambuco-Brazil

The counties of Pedra and Venturosa have one of the largest natural radioactive occurrences of Brazil. The large farms producing milk in the state of Pernambuco are located in these counties. The forage plants cultivated on those farms have high concentrations of ²²⁸Ra, a naturally occurring descending radionuclide from the ²³²Th series. The ²²⁸Ra is transferred to the forage plants, and once ingested by the lactating cow, this radionuclide is rapidly transferred to the milk. Thus, milk intake is an important route for ²²⁸Ra of incorporation by the human consumer and may induce the appearance of bone sarcoma. Accordingly, the aim of the present study was to determine the concentrations of ²²⁸Ra in milk produced in the Pedra and Venturosa farms, in order to estimate the risk of ingestion in the local population. The ²²⁸Ra was determined by actin-228 (²²⁸Ac) using the radiochemical technique of barium sulphate precipitate (BaSO₄). The milk samples had concentrations of ²²⁸Ra ranging from 61 to 1338 mBq.l^?1, which corresponded to the cumulative equivalent dose ranging from 0.04 to 0.1 Sv. Although the doses were low, regulatory and protective measures should be taken to study the radiotoxic effects of ²²⁸Ra in subjects in the public.     

紫外分光光度法测定水体总氮的影响因素

本文就紫外分光光度法在测定水体总氮中易影响测定工作的几个方面做了阐述,并提出了改进意见     

新一代多模型迭代算法在70 kVp成人副鼻窦CT扫描中的应用

探讨成人在70 kVp副鼻窦CT检查中降低有效辐射剂量的同时,获取最佳图像质量的新一代多模型迭代算法(Adaptive Statistical Iterative Reconstruction-V,Asir-V)的权重。本研究对20例成人患者进行副鼻窦Revolution CT检查,采用70 kVp、230 mA条件下进行螺旋CT扫描,扫描完成后对每例患者的原始数据采用不同权重(0,20%,40%,60%,80%,100%)的后置新一代多模型迭代算法(Adaptive Statistical Iterative Reconstruction-V,Asir-V)重建的方法,共获得120幅图像,并对每例6组图像进行客观评价及主观评分。客观评价包括噪声(standard deviations, SD)和对比噪声比(contrast noise ratio,CNR),主观评价由2名评价医生对图像质量评分并对两者的主观一致性进行评价。每例患者扫描完成后,记录其剂量长度乘积(dose-length product,DLP)和CT容积剂量指数(CT dose index volume,CTDI_vol),并计算其平均有效辐射剂量(effective dose,ED)。客观评价结果表明不同权重的Asir-V图像噪声随着Asir-V权重的提升而降低,CNR值随着Asir-V权重的提升而升高,且有效辐射剂量ED较常规头颈部CT检查的平均辐射剂量明显减少;主观评价结果表明不同权重的Asir-V图像评分不同,在Asir-V 60% 时评分最高,且2名医生主观评价一致性好。结合主客观评价结果,认为在70 kVp、230 mA成人副鼻窦Revolution CT检查中,Asir-V 60％的图像既可满足临床诊断的需要,也可明显降低有效辐射剂量。     

Phenolic composition of Merlot and Cabernet-Sauvignon grapes from Bordeaux vineyard for the 2009-vintage: Comparison to 2006, 2007 and 2008 vintages

Cabernet-Sauvignon and Merlot skin and seed extracts from Bordeaux grapes were investigated to determine both grape variety and vintage effect on phenolic composition. The total content of polyphenols and tannins in Merlot seeds was higher than that of Cabernet-Sauvignon allowing to discriminate the varieties. HPLC analyses underlined significant differences in the absolute concentration of proanthocyanidins amongst the two varieties and in their composition: mean degree of polymerisation (mDP) and percentage of galloylation of seed extracts were good indicators of grape variety. The vintage effect on the phenolic composition was confirmed for 2009 in comparison to previous vintages. Low values of mDP and concentrations of proanthocyanidins and anthocyanins were found in 2009 seeds and skins. The climatic conditions of 2009 (high rainfall before flowering followed by a strong hydric stress during berries development until ripening) let us hypothesise a lower activation of flavonoid pathway.     

Kinetic analysis of non-enzymatic browning in carrot juice concentrate during storage

The effect of storage temperature, storage time and total soluble solid (TSS) on the total sugar (TS), sucrose, glucose, fructose, total amino acid (TAA), pH, 5-hydroxymethylfurfural (HMF) and browning degree (BD) in carrot juice concentrate (CJC) stored at −18, 0, 25 and 37 °C was studied and the relationship between HMF and BD was established. Higher temperature at 25 and 37 °C had a significant effect (p<0.05) on TS, sucrose, glucose, fructose, TAA, pH, HMF and BD, while lower temperature at 0 and −18 °C had less effect, and the storage time and the soluble solid of CJC stored at 25 and 37 °C also had a significant effect on HMF formation and BD. At 25 and 37 °C, the formation of HMF and BD followed a first-order reaction well as a function of storage time; a good correlation between HMF formation and BD occurred. The formation of HMF could described by the total soluble solid value [TSS] and the BD value ([BD], absorbance at 420 nm) of CJC, the equation was [HMF] (content of HMF) = 1.2177 − 0.1124 × [TSS] + (2.835 + 0.3477 × [TSS]) × [BD] and [HMF] = 1.5510 − 0.4813 × [TSS] + (23.8847 + 0.7249 × [TSS]) × [BD] at 25 and 37 °C, respectively.     

Development of a sensitive picrate method to determine total cyanide and acetone cyanohydrin contents of gari from cassava

The sensitivity of the normal picrate method for determination of total cyanide in cassava was increased tenfold using a small 1 cm² picrate paper, eluted using 0.5 mL instead of 5 mL of water as in the normal method. The absorbance was measured in a 2 mm cuvette in the spectrophotometer. The sensitive method was calibrated against the normal picrate method. The total cyanide content in mg HCN equivalents/kg sample = ppm, is calculated from the absorbance (A) by the equation ppm = A × 45.7 which is applicable from 0.1 to 50 ppm. A new method to determine acetone cyanohydrin was developed based on irreversible denaturation of linamarase in 0.1 M HCl at 30 °C for 1 h. Five gari samples from Mozambique gave a mean total cyanide content of 12 ppm (range 6–15 ppm) and mean acetone cyanohydrin content of 11 ppm (range 5–14 ppm). Acetone cyanohydrin liberates cyanide quantitatively in the human intestine.     

住宅用全热回收换气机防结霜的研究

本文针对住宅用新风换气机在冬季运行时，在其排风侧出现结霜现象，以实验测定为研究手段，选用板翅武全热交换器作为能量回收装置，设计加工了防结霜住宅用全热回收换气机样机。样机安装在标准的住宅内，测定了该换气机在冬季运行时，其结霜点的温度随室内外空气温湿度的变化情况，总结其结霜的变化规律，得出通过新风预热能够有效地防止换气机冬季结霜现象的发生，使其应用得到进一步的推广的结果。     

The Impact of Sub-Millisecond Damage Fixation Kinetics on the In Vitro Sparing Effect at Ultra-High Dose Rate in UNIVERSE

The impact of the exact temporal pulse structure on the potential cell and tissue sparing of ultra-high dose-rate irradiation applied in FLASH studies has gained increasing attention. A previous version of our biophysical mechanistic model (UNIVERSE: UNIfied and VERSatile bio response Engine), based on the oxygen depletion hypothesis, has been extended in this work by considering oxygen-dependent damage fixation dynamics on the sub-milliseconds scale and introducing an explicit implementation of the temporal pulse structure. The model successfully reproduces in vitro experimental data on the fast kinetics of the oxygen effect in irradiated mammalian cells. The implemented changes result in a reduction in the assumed amount of oxygen depletion. Furthermore, its increase towards conventional dose-rates is parameterized based on experimental data from the literature. A recalculation of previous benchmarks shows that the model retains its predictive power, while the assumed amount of depleted oxygen approaches measured values. The updated UNIVERSE could be used to investigate the impact of different combinations of pulse structure parameters (e.g., dose per pulse, pulse frequency, number of pulses, etc.), thereby aiding the optimization of potential clinical application and the development of suitable accelerators.     

Model of a total momentum filtered energy selective electron heat pump affected by heat leakage and its performance characteristics

A total momentum filtered energy selective electron (ESE) heat pump model with heat leakage is established in this paper. The analytical expressions of heating load and coefficient of performance (COP) for both the total momentum filtered (k_r-filtered) ESE heat pump and the conventionally filtered (k_x-filtered) ESE heat pump in which the electrons are transmitted according to the momentum in the direction of transport only are derived, respectively. The optimal performance of the k_r-filtered ESE heat pump is analyzed by using the theory of finite time thermodynamics (FTT). The optimal regions of COP and heating load for the k_r-filtered heat pump are obtained. By comparing the performance of the k_r-filtered device with that of the k_x-filtered device, it is found that the heating load performance and the COP versus heating load characteristic curves of the k_r-filtered heat pump are totally different from those of the k_x-filtered device; and the maximum COP and maximum heating load of the k_r-filtered device are generally higher than those of the k_x-filtered device. The influences of heat leakage, resonance width, hot reservoir temperature and chemical potential on the performance of the total momentum filtered ESE heat pump are further analyzed by numerical calculations. The obtained results can provide some theoretical guidelines for the design of practical electron systems such as solid-state thermionic heat pump devices.     

An energy balance and greenhouse gas profile for county Wexford,Ireland in 2006

In this paper an energy balance and a greenhouse gas profile has been formulated for the county of Wexford, situated in the south east of Ireland. The energy balance aims to aggregate all energy consumption in the county for the year 2006 across the following sectors; residential, agriculture, commerce and industry, and transport. The results of the energy balance are compared with the previous energy balance of 2001 where it is found that the residential sector is the biggest emitter of CO₂ with 38% of total emissions with the transport and industry/commerce sectors sharing second place on 28%. Consumption of oil is seen to have increased significantly in nearly all sectors, accounting for over 70% of the total final energy consumed (TFC) while the total primary energy requirement (TPER) sees oil consumption accounting for 91% of all fuels consumed. To take into account the contribution of agriculture in total GHG emissions the gases CH₄ and N₂O will be estimated from the agricultural and waste sectors. The results show that methane contributes 25% of total GHG emissions with agriculture being the primary contributor accounting for 36% of total emissions.