Monte Carlo dose in a prosthesis phantom based on exact geometry vs streak artefact contaminated CT data as benchmarked against Gafchromic film measurements

PurposeIn radiotherapy, accurate calculation of patient radiation dose is very important for good clinical outcome. In the presence of metallic implants, the dose calculation accuracy could be compromised by metal artefacts generated in computed tomography (CT) images of patients. This study investigates the influence of metal-induced CT artefacts on MC dose calculations in a pelvic prosthesis phantom.MethodsA pelvic phantom containing unilateral Ti prosthesis was CT-scanned and accurate Hounsfield unit (HU) values were assigned to known materials of the phantom as opposed to HU values produced through the artefact CT images of the phantom. Using the DOSXYZnrc MC code, dose calculations were computed in the phantom model constructed from the original CT images containing the artefacts and artefact-free images made from the exact geometry of the phantom with known materials. The dose calculations were benchmarked against Gafchromic EBT3 film measurements using 15 MeV electron and 10 MV photon beams.ResultsThe average deviations between film and MC dose data decreased from 3 ± 2% to 1 ± 1% and from about 6 ± 2% to 3 ± 1% for the artefact and artefact-free phantom models against film data for the electron and photon fields, respectively.ConclusionsFor the Ti prosthesis phantom, the presence of metal-induced CT artefacts could cause dose inaccuracies of about 3%. Construction of an artefact-free phantom model made from the exact geometry of the phantom with known materials to overcome the effect of artefacts is advantageous compared to using CT data directly of which the exact tissue composition is not well-known.     

Adult rat hepatocytes cultured on an oxygen-permeable film increases the activity of albumin secretion

Primary culture of rat hepatocyte was performed in an oxygen-permeable film dish (F-dish), which would be expected to give an oxygen-rich culture condition. In the conventional culture dish in which the depth of medium was 2 mm, the oxygen tension (pO₂) in the medium decreased from 19% (144 mmHg) to 0.3% (2.3 mmHg) within 2 hr, while the pO₂ in the F-dish maintained 8.5% (64.6 mmHg) even after 2 hr. The adverse effect of the oxygen-deficiency appeared in the albumin secretion activity of the hepatocytes and it was more remarkable in the early period of culture. The average rate of albumin secretion for the initial 48 hr was 2.0 μg ml^-1 hr^-1 or 96 μg 10⁶ cells^-1 day^-1 in the F-dish. The average rate of albumin secretion for the initial 12 hr was only 0.36 μg ml^-1 hr^-1 in the conventional culture dish. The activity of ammonia elimination in the F-dish was 20–50% higher than the conventional culture dish. Three-dimensional aggregate was formed only in the F-dish. The advantage of three-dimensional aggregate for albumin secretion was not clear compared with two-dimensional monolayer. This revised version was published online in July 2006 with corrections to the Cover Date.     

地膜覆盖和施氮量对旱作春玉米农田净温室效应的影响

以旱作雨养条件下的春玉米为试验对象,在长武黄土高原农业生态试验站进行田间试验,研究了地膜覆盖和施氮量对农田净温室效应和温室气体排放强度的影响.结果表明:采用地膜覆盖与增加施氮量都会影响净温室效应与温室气体排放强度,地膜覆盖条件下(FM),不同施氮量的春玉米产量为1643~16699 kg·hm-2,净温室效应(CO_2当量,下同)为595~4376 kg·hm^-2·a^-1,温室气体排放强度为213~358 kg·t^-1;无覆膜条件下(UM),不同施氮量的春玉米产量为956~8821 kg·hm-2,净温室效应为342~4004 kg·hm^-2·a^-1,温室气体排放强度为204~520 kg·t^-1.研究表明,对于旱作春玉米农田系统,地膜覆盖可以有效降低温室气体排放强度,增加作物产量,地膜覆盖下施氮250 kg·hm-2可以实现高产与降低环境代价的双赢.     

《应用生态学报》2016年影响因子和总被引频次

据中国科学技术信息研究所发布的《2017年版·中国科技期刊引证报告（核心版）》,《应用生态学报》2016年影响因子为1．967,在生态学类期刊中排名第2位;总被引频次为12948,在生态学类期刊中排名第2位．感谢各位读者、作者和专家的支持!     

生物降解膜对甘肃河西棉花的生态生物学效应

为研究生物降解膜对甘肃河西棉田的保温保墒、棉花生长发育和产量的影响,于2016年和2017年设置厚度为0.012 mm的生物降解膜A、厚度0.008 mm的生物降解膜B、普通地膜、裸地4个处理,分析降解膜的降解性能及其对棉田土壤温度、水分、产量和相关因子及杂草防效的影响.结果表明: 降解膜B早于降解膜A 3～5 d进入诱导期,降解速率高于降解膜A.填埋180 d时,降解膜A和B失重率分别达到95.6%和94.5%;降解膜A在棉花苗期增温保水性效果较好,与普通地膜无显著差异;而降解膜B由于降解速率快,在苗期增温保水性显著低于普通地膜.覆盖降解膜较普通地膜延长了棉花生育期,但棉花出苗率、单株铃数、铃质量和衣分无显著差异,而霜前花率和杂草防效显著降低.产量结果显示,两年间降解膜A较普通地膜籽棉产量分别降低3.8%和3.1%,差异不显著,较裸地处理分别增产73.1%和59.9%,增产显著,而降解膜B较普通地膜减产11.8%和7.1%,差异显著.综上,降解膜A具有较好的增温保墒和增产效应,可在甘肃河西农业区推广应用.     

Integrating thin film microfluidics in developing a concise synthesis of DGJNAc: A potent inhibitor of α-N-acetylgalctosaminidases

A simple synthesis, which utilizes a thin film microfluidic reactor for a problematic step, of a potent inhibitor of α-N-acetylhexosaminidases, DGJNAc, has been developed.     

Efficient Non‐Fullerene Organic Photovoltaic Modules Incorporating As‐Cast and Thickness‐Insensitive Photoactive Layers

In this work, a new combination of a wide bandgap polymer poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]‐dithiophene‐alt‐N‐(2‐hexyldecyl)‐5′5‐bis[3‐(decylthio)thiophene‐2‐yl]‐2′2‐bithiophene‐3′3‐dicarboximide] (PBTIBDTT) and a non‐fullerene small molecule acceptor based on a bulky seven‐ring fused core (indacenodithieno[3,2‐b]thiophene) end‐capped with 2‐(3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile groups with one fluorine substituent (ITIC‐F) is proposed, and as‐cast non‐fullerene organic solar cells (NFOSCs) with 11.2% efficiency are achieved. The device efficiencies are also insensitive to the variation of photoactive layer (PAL) thickness and can maintain over 9% efficiency as PAL thickness increases to 350 nm, which is one of the best results for as‐cast organic solar cells. More importantly, non‐fullerene organic photovoltaic (OPV) modules are demonstrated via laser ablation technique for the first time, which delivers a record efficiency of 8.6% (with active area of 3.48 cm²) among large‐area OPV modules. Furthermore, the morphology and performance evolutions of the as‐cast NFOSCs and the ones processed with solvent additive are systematically investigated. The results demonstrate the great advantage of as‐cast solar cells in achieving constant morphology and high performance with thick PALs. The NFOSCs fabricated with simple procedure, insensitive to film thickness and compatible with large‐area OPV modules, show significant potential for application the future.     

Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit

Objective

Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit.

Chitosan functional properties

Chitosan is a partially deacetylated polymer of N-acetyl glucosamine. It is essentially a natural, water-soluble, derivative of cellulose with unique properties. Chitosan is usually prepared from chitin (2 acetamido-2-deoxy β-1,4-D-glucan) and chitin has been found in a wide range of natural sources (crustaceans, fungi, insects, annelids, molluscs, coelenterata etc.) However chitosan is only manufactured from crustaceans (crab and crayfish) primarily because a large amount of the crustacean exoskeleton is available as a by product of food processing. Squid pens (a waste byproduct of New Zealand squid processing) are a novel, renewable source of chitin and chitosan. Squid pens are currently regarded as waste and so the raw material is relatively cheap. This study was intended to assess the functional properties of squid pen chitosan. Chitosan was extracted from squid pens and assessed for composition, rheology, flocculation, film formation and antimicrobial properties. Crustacean chitosans were also assessed for comparison. Squid chitosan was colourless, had a low ash content and had significantly improved thickening and suspending properties. The flocculation capacity of squid chitosan was low in comparison with the crustacean sourced chitosans. However it should be possible to increase the flocculation capacity of squid pen chitosan by decreasing the degree of acetylation. Films made with squid chitosan were more elastic than crustacean chitosan with improved functional properties. This high quality chitosan could prove particularly suitable for medical/analytical applications. This revised version was published online in November 2006 with corrections to the Cover Date.     

玉米地膜制种促熟增产的生理学机理

系统地探讨了玉米地膜制种促熟增产的作物生理学机理．结果表明,玉米池膜制种可以改善土壤水温条件、增强植株根系活力和群体光合作用性能、促进植株生长发育和光合产物的积累与分配．为该技术应用提供了科学依据．