N+注入对甘草幼苗部分耐旱特征效应的研究

植物幼苗主根、侧根及下胚轴的生长和根冠比值的大小是幼苗耐旱的重要特征.对甘草干种子注入能量为25 kev、注量为600×2.6×1013-3600×2.6×1013/cm2的N+,其中1800×2.6×1013/cm2的N+注入量能有效提高甘草6 d幼苗的主根生长和30 d幼苗根冠比干重和鲜重,促进侧根发生;也能明显刺激6 d和30 d幼苗的下胚轴和主根、茎高的生长.该参数可以作为沙漠化地区建立甘草植被发挥离子束注入当代效应的N+辐照的能量、注量的参考参数.在实验注入N+的参数范围内甘草幼苗耐旱特征的应答也表现出"损伤-修复-损伤"效应.     

产维生素K_2黄杆菌复合诱变及发酵优化

利用亚硝基胍(NTG)和低能氮离子束(N+)注入复合诱变方法,获得产维生素K2黄杆菌(Flavobacterium sp.)菌株,并对突变菌株发酵条件进行优化,进一步提高黄杆菌产维生素K2的能力。确定最佳诱变条件为:NTG处理浓度0.8 mg/m L,处理时间20 min;N+离子注入能量15 ke V,80(2.6×1013 cm?2),突变菌维生素K2产量为6.12 mg/L,较原始菌株提高了159%。突变菌传代6次,维生素K2产量稳定。进一步优化突变菌发酵条件,确定最优发酵条件为:温度37℃、起始p H=7.0,装液量30 m L/250 m L,接种量2%、摇床转速120r/min,发酵后72 h添加3 mg/m L花生衣(Arachis hypogaea)作为诱导物,优化后的菌株维生素K2产量较优化前提高31%。     

~(12)C离子束辐照对酵母发酵能力的影响

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。     

绿色木霉原生质体的激光诱变及纤维素酶发酵条件优化

采用Nd:掺钕的钇铝石榴石固体激光器,在266 nm激发波长下,对绿色木霉CICC13038原生质体进行辐照诱变,通过微晶纤维素筛选,得到高产纤维素酶的菌株JG13,运用正交试验对诱变菌株发酵条件进一步优化,在28℃、180 r/min、发酵72 h条件下的正交试验结果表明:发酵条件为1%(NH4)2SO4为氮源,2%麸皮为碳源,0.5%Tween-80为产酶促进剂,瓶装量25 mL(250 mL 发酵瓶),纤维素酶酶活可达35.68 U/mL,相同发酵条件下,较原始菌株酶活提高25.76%.菌株JG13也可作为进一步诱变筛选的出发菌株,获得更高活性菌株.     

氮离子注入生物絮凝剂产生菌的诱变效应研究

采用30 keV氮离子注入对生物絮凝剂产生菌进行诱变选育,研究低能氮离子对微生物的诱变效应.结果表明:FJ-7 菌株的存活率曲线为典型的"马鞍型"剂量.效应曲线.经5x1015 ions·cm-2 N 注入诱变处理,最终获得一株絮凝活性高、遗传稳定性良好的突变株NIM-192.其发酵产絮凝剂曲线表明,突变株NIM-192的菌体生长速度稍慢于原始菌株,但其絮凝活性一直高于原始菌株,絮凝率比原始菌株提高了34.26%.这很可能是离子注入菌体后所产生的生物学效应使得菌体合成更多的絮凝剂,导致絮凝活性的增强.     

氮离子注入选育高效发酵木糖生产L(+)-乳酸的米根霉

为了获得能够高效发酵木糖生产L( )-乳酸的菌株,采用氮离子注入诱变方法,对出发菌株米根霉RLC41-6进行改良,获得高产L( )-乳酸菌株RQ4012,发酵周期为72h,产酸能力达74.37g/L,产酸速率达1.03g/(L.h),比RLC41-6提高了1.6倍.经过多次传代实验证明该菌株具有较好的遗传稳定性.     

低能N~+注入选育黑曲霉β-葡萄糖苷酶高产菌株及其发酵优化研究

为了获得β-葡萄糖苷酶高产菌株,应用低能N+注入技术对黑曲霉菌株Au进行了诱变选育,同时研究了N+注入对菌株存活率和突变率的影响。通过几轮注入之后,最终筛选得到的高产菌株Au 0847其β-葡萄糖苷酶活力达到13.75 U/mL,比原始菌株Au提高了106.8%,且遗传性能稳定。经过进一步的发酵优化,该菌株最终β-葡萄糖苷酶活力达到30.53 U/mL。     

氮离子注入番茄红素产生菌诱变选育的研究

采用了低能氮(N )注入技术,对发酵生产番茄红素的三孢布拉霉Blakeslea trispora(-)进行了诱变选育研究.实验结果表明N 注入B.trispora(-)后得到较高的突变率和较广的突变谱,并通过诱变筛选得到BH3-701等4株高产菌株,经过连续五代遗传稳定性实验考察,高产菌株番茄红素的平均产量比出发菌株提高50%.其中BH3-701表现出很强的发酵积累番茄红素的能力,尤其在发酵后期更为突出,极大地提高了生产效率.     

离子注入过程中拟南芥愈伤组织冻害的防护研究

以拟南芥愈伤组织为对象,探讨了 DMSO(二甲亚砜)处理和玻璃化处理两种方法对愈伤组织在注入过程中冻害的防护。结果表明,玻璃化处理较 DMSO 处理能更有效地对冻害进行防护,N+注入量增至200×2.6×1013cm? 时,仍有 60%左右的愈伤组织可以正常分化。此工作对于以活体材料为注入对象的研究有一定的实际意义。     

氮离子束注入诱变选育胞外多糖高产菌株

采用氮离子束注入胞外多糖产生菌进行诱变处理来获得胞外多糖高产菌株。氮离子注入过程采用的能量为10 keV,剂量为60×1014–140×1014cm-2。根据其存活率及突变率确定最佳的注入剂量。结果表明:菌株存活率曲线遵循氮离子注入生物效应的"马鞍型曲线",当注入剂量为120×1014cm-2时,获得了最佳的诱变效果。通过筛选和连续5次传代,获得具有良好稳定性的突变株,其多糖产量达到3.29 g/L,较出发菌株提高了19.20%,且发酵周期缩短了6 h。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.