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| 个人信息 |
| 姓 名： |
陈译员 [编号]:350 |
性 别： |
男 |
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| 擅长专业： |
农业食品化学生物化学，细胞生物学分子生物学，植物化学营养与健康天然产物化 |
出生年月： |
1979/5/1 |
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| 民 族： |
汉族 |
所在地区： |
湖北 武汉 |
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| 文化程度： |
硕士 |
所学专业： |
农业应用生物技术 |
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| 毕业时间： |
38878 |
毕业学校： |
浙江大学 |
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| 第一外语： |
英语 |
等级水平： |
6 |
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| 口译等级： |
3 |
工作经历： |
3 年 |
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| 翻译库信息 |
| 可翻译语种： |
英语、日语 |
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| 目前所在地： |
湖北 武汉 |
| 可提供服务类型： |
笔译、家教 |
| 每周可提供服务时间： |
周二,周四,周末全天,周一，周三,周五晚上 |
| 笔译案例信息 |
| 案例标题： |
聚丙烯纤维的辐射接枝改性研究 |
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| 原文： |
摘 要 以聚丙烯（PP）纤维为基体，采用γ射线辐射方法，分别接枝了丙烯酸十二酯和丙烯酸丁酯。在氮气氛条件下进行共辐射聚合反应，讨论了单体浓度和交联剂浓度对接枝率的影响，接枝率随着单体和交联剂浓度的提高均为先增大后减小。聚丙烯纤维接枝丙烯酸丁酯最大接枝率为20.53%，聚丙烯纤维接枝丙烯酸十二酯最大接枝率为29.90%。接枝后的PP纤维进行红外（IR）等结构表征，作了热重（TG）、差示扫描量热法（DSC）等性能测试，并分别作了接枝前后的扫描电镜图，表明丙烯酸十二酯和丙烯酸丁酯均已接枝到PP基体上。
关键词 聚丙烯 丙烯酸丁酯 丙烯酸十二酯 辐照接枝 纤维
聚丙烯(PP)纤维本身具有良好疏水亲油的特性,密度比水小,可悬浮在水面上,对烃类、酯类、酮类、卤代烃等各种有机溶剂型油品具有较高的吸收率。人们对PP进行了大量的改性研究以更大程度的利用其吸油性能，丙烯酸，丙烯腈，丙烯酰胺，丙烯酸酯等[1-3]单体都被有效的接枝在PP的分子链上，从而使聚丙烯具有更好的应用性能。陈晓婷等[4]以丙烯酸酯、甲基丙烯酸酯为主要单体，二丙烯酸丁二醇酯为交联剂，过氧化二苯甲酰为引发剂，采用悬浮聚合方法，合成聚丙烯酸酯类高吸油树脂。结果表明，吸甲苯倍率可达15倍，吸汽油倍率可迭10倍；张宇东等[5]采用预辐射的方法将丙烯酸乙酯接枝到了聚丙烯上；陈捷等[6]采用预辐射的方法在聚丙烯上接枝了甲基丙烯酸聚乙二醇酯；董缘等人[7]采用预辐射的方法在聚丙烯无纺布上分别接枝了甲基丙烯酸甲酯和丙烯酸甲酯。Jung-Dae Cho[8]等对聚丙烯在苯甲酮存在下进行紫外辐射接枝6-己二醇二丙烯酸酯，并对其结构和性能进行了表征和测定。本研究以聚丙烯纤维为基体，利用γ射线辐照的方法在聚丙烯纤维上接枝丙烯酸十二酯(LA)，丙烯酸丁酯(BA)。
2 实验部分
2.1 原料及试剂
聚丙烯纤维：烟用聚丙烯丝束(石家庄卷烟厂提供)；丙烯酸十二酯(LA)：天津市天骄化工有限公司，工业级；甲苯：天津市北方天医化学试剂厂，分析纯；无水乙醇：天津市大茂化学试剂厂，分析纯；二乙烯苯(DVB)：天津市北方天医化学试剂厂，分析纯。
2.2 主要仪器
钴(Co)源：天津华明高科辐照有限公司；402型电热真空干燥箱：天津实验仪器厂；HZQ-C型空气浴振荡器：哈尔滨市东明医疗仪器厂；VECTOR22型FI-IR仪：德国BRUKER公司； S-3500N型扫描电子显微镜；NETZSCH STA409PC型热重分析仪，德国；PERKIN-ELMER型差热分析仪，美国；
2.3聚丙烯纤维的接枝改性
在大试管中依次加入一定量的溶剂、单体和交联剂，鼓氮气10min除氧并使溶液均匀混合，加入PP纤维后再充氮气10min，然后密封，经60Co γ射线辐照数小时后把样品取出。将接枝后的纤维先用无水乙醇冲洗，再用丙酮抽提，以除去均聚物，然后将纤维干燥至恒重，按照公式1-1计算接枝率G。
G(%)=[(Wg-W0)/ W0]×100% (1-1)
式中，W0和Wg分别为接枝前后PP纤维的质量。
2.4纤维红外光谱的测定
将原纤维、接枝纤维干燥后，用德国Bruker公司的Vector-22型傅立叶变换红外光谱仪测定纤维组成。
2.5扫描电镜
将纤维用胶带固定在样品台上，真空喷金后，在HITACHI S-3500N型扫描电子显微镜上观察纤维的表面形态。
2.6纤维的TG分析
将纤维样品剪碎，以10℃/min的升温速率从0℃升至600℃，在氮气条件下利用NETZSCH STA409PC型热重分析仪进行热重分析。
2.7纤维的DSC分析
称取约10mg的样品, 以10℃/min 的升温速率从20℃升至200℃，利用PERKIN-ELMER型差热分析仪对样品进行DSC 测试。
3 结果与讨论
3.1 接枝前后纤维的红外谱图(ATR-FTIR)
图1给出了聚丙烯纤维接枝前后的红外光谱， 1、2、3分别代表原纤维，丙烯酸十二酯接枝后的PP纤维（PP-g-LA）和丙烯酸丁酯接枝后的PP纤维（PP-g-BA）。图中2960~2915cm-1为CH3，CH2的不对称伸缩振动。2870~2840cm-1为CH3，CH2的对称伸缩振动；1455cm-1附近为CH3为的不对称弯曲振动峰，1375cm-1附近为CH2的对称弯曲振动峰。
从图2、3与图1的比较中可以看出，接枝纤维的红外谱图在1730cm-1附近出现明显的脂肪酸酯的羰基伸缩变形振动峰，表明聚丙烯纤维上引入了羰基集团；在1150cm-1左右出现的为C—O的伸缩振动峰，1150cm-1~1180cm-1，1240cm-1~1270cm-1这两组峰表征的是C—C—O—C的伸缩振动峰，结合羰基振动峰，说明有酯基存在。图3中720cm-1附近的尖的弱峰为(CH2)n（n≥4）的C—H变形振动，说明是丙烯酸十二酯支链被接到了聚丙烯上。
接枝后纤维的谱图在1000cm-1~1500cm-1之间变得十分复杂，这是由于接枝后引入了季碳离子和羰基等对甲基弯曲振动峰的影响以及C—O—C基在1000cm-1~1300cm-1附近的峰位所致。
综上所述，说明单体LA、BA均接枝到原纤维上了。
图1 聚丙烯纤维接枝丙烯酸酯前后的红外谱图
3.2扫描电镜(SEM)
(a) PP (b) PP-g-LA
(c) PP (d) PP-g-BA
图2 聚丙烯纤维接枝丙烯酸酯前后的扫描电镜图
从图中可以明显的看出，接枝后的纤维的表面明显的发生了变化，与原纤维光滑的表面形成对比，接枝后的纤维表面有明显的接枝层，再次验证了单体接枝到了PP纤维上
3.3纤维的TG分析
图3 接枝纤维前后的TG分析
图4 接枝纤维前后的DTG分析
对同一升温速率下（升温速率为10℃/min）原纤维以及接枝丙烯酸丁酯、丙烯酸十二酯后的纤维在N2中的失重行为进行比较，如图3、图4所示。
由TG、DTG图可以看出，PP-g-BA、PP-g-LA纤维的热分解为两步，分别对应着丙烯酸酯接枝链分解及PP基体纤维的分解。接枝链的分解是从371.6℃开始，到425℃结束，峰值出现在400.9℃。PP纤维基体的分解则从455.6℃开始，到649.3℃结束。
TG分析结果表明，接枝纤维具有较好的耐热性能，在N2中的使用温度可以达到370℃。
3.4纤维的DSC分析
图5接枝纤维前后的DSC分析
由表5中的数据可以看出，接枝后纤维的熔融焓降低，这是由接枝链对晶区的“稀释作用”以及辐射反应对PP纤维的晶区的“破坏作用”[9,10]造成的。为表征PP纤维接枝后PP组分结晶度的变化，对其结晶度Wc进行了计算。计算公式为：
△Hf(PP)=△Hf(fiber) /(1-α) (2-6)
Wc(%)=△Hf(PP) /△Hf(cys)×100 (2-7)
其中，△Hf(fiber)、△Hf(PP) 以及△Hf(cys) 分别为PP接枝纤维，接枝纤维中PP组分以及结晶度为100%的PP纤维的熔融焓，且△Hf(cys)约为209J/g[11]；α为接枝物在所制备的接枝纤维中的质量分数。
表1 接枝前后纤维的DSC资料
Samples and Grafting degree (%) Tm (℃) △Hf(fiber) (J/g) △Hf(PP) (J/g) Wc (%)
1 PP 163.8 88.36 88.36 42.28
2 PP-g-LA (15.75%) 162.7 79.27 94.08 45.01
3 PP-g-BA (15.88%) 163.4 77.79 90.14 43.13
由图5可以看出，接枝后聚丙烯纤维的熔程略有增加，而接枝后纤维的熔融温度较原纤维略有下降。影响熔融温度的因素主要有两方面，一方面是因为在进行接枝反应时，反应主要发生在聚丙烯的无定型区或晶区缺陷处的PP主链上，引入接枝链后纤维晶区的规整性变差，破坏了PP组分的固有结晶区，因而聚丙烯接枝产物的熔点降低。另一方面是因为接枝链聚合物形成了新的结晶，而且其熔融温度与原纤维不同。当接枝链的熔点低于原纤维或者不能形成结晶时，接枝纤维的熔点比原纤维降低，反之可能会增加。
而且由表1中数据可知，接枝后纤维的熔融焓△Hf(PP)和结晶度Wc与原纤维相比略有提升。
3.5单体浓度对纤维接枝率的影响
图6 单体浓度对纤维接枝率的影响
由图可看出，随着单体浓度的增加，丙烯酸十二酯和丙烯酸丁酯的接枝率先增大后降低，当丙烯酸十二酯单体浓度为7.5%时，PP-g-LA接枝率达到最大值29.90%；当丙烯酸丁酯单体浓度为10%时，，PP-g-BA接枝率达最大值20.53%，。由于接枝率不仅与单体捕捉自由基的能力有关，还与单体向聚合物基体扩散的状况有关。当单体浓度太小时，含自由基的单体向PP基体扩散缓慢，接枝率因而受到影响。随着单体浓度的增加，自由基与单体碰撞的几率增加，与纤维表面的活性点接触几率增加，从而使接枝率增加。但是随着单体浓度进一步的增加，单体自聚加剧，自聚生成的均聚物一方面使反应体系的粘度增加，降低了单体的扩散速率，另一方面自聚反应减少了能进行扩散的单体数量，使得扩散到PP纤维表面的单体数量减少，这两种情况共同导致单体与活性点接触的几率下降，从而导致接枝率下降。
3.6交联剂浓度对纤维接枝率的影响
图7 交联剂浓度对纤维接枝率的影响
由图可看出，随着交联剂浓度增加，接枝率迅速增大，当达到一个最大值后，接枝率又开始下降。当交联剂浓度为2%时，丙烯酸丁酯接枝率达到最高值20.53%，丙烯酸十二酯接枝率达到最高值21.64%。这是因为交联剂具有两个双键，与丙烯酸酯相比，应该具有更高的反应活性，因此当交联剂浓度过低时，接枝到纤维上的可能大部分都是交联剂而并非丙烯酸酯，导致接枝率较低；当交联剂浓度过高时，丙烯酸酯单体自聚严重，阻碍单体向自由基扩散，影响接枝反应的进行。
4 结论
1．对接枝后的PP纤维进行红外（IR）结构表征，作了热重（TG）、差示扫描量热法（DSC）等性能测试，并分别作了接枝前后的扫描电镜图，均表明丙烯酸酯已经接到了PP上。
2．聚丙烯纤维接枝丙烯酸丁酯最大接枝率为20.53%，接枝率随着单体和交联剂浓度的提高均为先增大后减小，说明单体和交联剂浓度过高或过低时，都导致接枝活性浓度减少，从而导致接枝率下降。聚丙烯纤维接枝丙烯酸十二酯最大接枝率为29.90%，接枝率随单体和交联剂浓度的变化趋势与丙烯酸丁酯类似，说明单体和交联剂浓度过高和过低，都不利于接枝反应。
参考文献
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[2] Hyun-Ju Park , Choon-Ki Na, J. Colloid. Interface. Sci. [J], 2006, 301: 46～54;
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[4] 陈晓婷，唐旭东，张明珠等，离子交换与吸附 [J]，2005，21(6)：536～54;
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[7] 董缘，兰新哲，李惊仙，应用化工[J]， 2006，35(8) ：569～572;
[8] Jung-Dae Cho，Soon-Gi Kim，Jin-Who Hong, J. Appl. Poly. Sci. [J], 2006, 99: 1446～1461
[9] 黄珍珍，林志丹，蔡泽伟，麦堪成．丙烯酸接枝聚丙烯的制备及其结构与性能[J]．工程塑料应用．2004，32（2）：71～74；
[10] 朱诚身．Structure analysis of polymers聚合物结构分析[M]．Beijing: Science press北京：科学出版社．2004；
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SYNTHESIS AND PROPERTIES OF HIGH OIL ABSORPTION RESINS Ion exchange and adsorption 丙烯酸酯类吸油树脂的合成与性能研究
STUDY ON PRE-IRRADIATION GRAFT COPOLYMERATION OF ETHYL ACRYLATE ONTO PP POWDER. POLYMER MATERIALS SCIENCE & ENGINEERING. PP预辐射接枝丙烯酸酯的研究
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聚丙烯无纺布预辐射固相接枝丙烯酸的研究 Study on pre-irradiation induced solid phase graft copolymerization of acrylic acid on non-woven polypropylene fabric. 应用化工APPLIED CHEMICAL INDUSTRY
丙烯酸接枝聚丙烯的制备及其结构与性能PREPARATION, STRUCTURE AND PROPERTIES OF POLYPROPYLENE GRAFTED WITH ACRYLIC ACID. 工程塑料应用ENGINEERING PLASTICS APPLICATION. |
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| 译文： |
Synthesis and Modification of Polypropylene by Radiation-induced Grafting
Abstract
Polypropylene fiber (PP) was radiation-induced graft polymerization of lauryl acrylate (LA) and butyl acrylate (BA) using a 60Co gamma radiation source. Then the grafted polypropylene fiber was characterized by a Fourier transform infrared (FT-IR) spectrometer, Scanning Electron Microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG), which indicated that LA and BA have been grafted onto PP. The article focused on some factors that influenced on the graft degree, such as the cross-linking agent concentration, monomer concentration. The results showed that: the degree of grafting BA reached the maximum of 20.53%, while the maximum graft degree of LA was 29.90%.
Keywords: Polypropylene; Butyl acrylate; Lauryl acrylate; Radiation grafting; Fiber;
1. Introduction
Polymers have generated considerable interest as biomaterials in medical science and biotechnology. With increasing demands for a biomaterial with better acceptability and functionality to the biosystem, stress has been focussed on the development of newer materials. One of the ways to develop such materials is to modify existing polymers and design them keeping in view their specific application areas. Sutures are used in surgical operations and require optimum physico-chemical characteristics. Polypropylene (PP) is one of the widely used biostable sutures due to its optimum tensile strength and low level of tissue reaction. PP fibers possess good hydrophobic and lipophilic properties with lower density than water, which can suspend in the surface of water and have a high adsorption capacity of organic solvents such as hydrocarbons, esters, ketones, halohydrocarbons and so on.Therefore, Modification or introduction of new characteristics to those based on synthetic polymers such as polypropylene, can be achieved by several methods. Grafting, whether initiated chemically or by ionizing radiations, constitutes one of the methods that is being applied successfully. The radiation-induced graft polymerization of monomers such as acrylates, methacrylic acid, acrylamide and acrylonitrile onto PP has been reported to introduce hydrogel characteristics in the polymer for biomedical applications (Bhuvanesh, 2006, PP. 161-167, Park, 2006, PP.46-54, Vahdata, 2007, PP.787-793). Chen Xiaoting (2005, PP.536-54 ) reported that using acrylates, methacrylates as monomers, butylene glycol diacrylate as crosslinking agent, BPO as initiator, the high oil absorption resins polyacrylate were synthesized by suspension polymerization. The oil absorption ability of the resin is more than 15(g/g) for toluene, 10(g/g) for gasoline and 9(g/g) for machine oil. Zhang Yudong (1999, PP. 79-82)reported that grafting of ethyl acrylate(EA) onto PP powder had been carried out by preirradiation method using gamma rays from 3.7×1014Bq 60Co source as initiator. Chen Jie (1999, PP.193-198) reported that the surface of polypropylene (PP) film was modified by preirradiation grafting of polyethylene glycol methacrylate (PEGMA) with three kind of different molecular weight. Dong Yuan (2006, PP. 569-572) et al have indicatedt that the matrix of non-woven polypropylene fabrics could be grafted with the monomer of acrylic acid by means of pre-irradiation induced solid phase graft copolymerization. Jung-Dae Cho et al (2006, PP. 1446-1461)reported that 1,6-Hexanediol diacrylate (HDDA) was grafted onto polypropylene (PP) substrates in the presence of benzophenone (BP) using UV radiation and the UV-radiation grafting polymerizations were characterized in detail using contact-angle measurements, Fourier transform infrared spectroscopy with attenuated total internal reflection, and scanning electron microscopy. In the present study, the graft polymerization of LA and BA onto PP monofilament is carried out by a radition-induced grafting method to develop sutures with different graft levels.
2. Materials and methods
2.1 Materials and reagents
Commercial polypropylene fabric was kindly provided by Shijiazhuang Cigarette Industries Co. LTD. LA and BA purchased from Tianjiao Chemical Co., LTD, Tianjin, were used without further treatment. Other chemicals were analytical grade.
2.2 Grafting and modification procedure
Strips of PP films were immersed in monomer, cross-linking agents in glass ampoules. The reactant mixtures in glass ampoules were dearated by bubbling nitrogen gas for10 min, sealed and then subjected to gamma ray irradiation from 60Co. The grafted films thus obtained were removed and washed thoroughly with distilled water and then soaked overnight in acetone to eliminate the residual monomer and homopolymer contained in the films. The films were then dried in an oven for 24 h at 50–60°C and then weighed. The degree of grafting G was calculated as follows:
G(%)=[(Wg-W0)/ W0]×100%
where, W0 and Wg represent, the weights of the initial and grafted films, respectively.
2.3 FTIR measurement
A Vector-22 Fourier transform infrared (FTIR) spectrometer, which is a product of Bruker, Co. Ltd, Germany, was used for measuring and scanning the infrared absorption spectra at resolution of 4 cm−1. High signal-to-noise spectra were obtained by collection of hundred scans for each sample. The resultant digitized spectra were stored for further data processing.
2.4 SEM analysis
The phase morphological characteristics of the samples were observed by means of SEM (HITACHI, S-3500N) in the normal secondary electron imaging (SEI) mode and all the membrane samples were coated with gold-palladium and fixed by adhesive tape in the sample stage.
2.5 TG analysis
All samples were sheared to pieces and sputter-coated with Au. A NETZSCH STA409PC (Germany) thermogravimetry (TG) analyzer was used for thermal stability determinations of all samples under nitrogen atmosphere at a heating rate of 10°C /min from 0°C to 600°C.
2.6 DSC analysis
The thermal properties of PP composites were measured using a differential scanning calorimetry (Perkin-Elmer DSC-7, USA). Samples of about 10mg were heated from 0 to 200°C, and then cooled down to 60 °C at the heating rate of 10 °C /min under an atmosphere of dry nitrogen.
3. Results and discussion
3.1 Infrared spectroscopy measurement
The presence of grafting of LA and BA onto PP film was confirmed by FTIR analysis. The IR spectra of virginal PP and grafted polymers PP-g-LA and PP-g-BA are given in Fig. 1. The appearance of the new bands at about 2960~2915 and 2870~2840 cm−1 on the pp matrix may be caused by the out-of-plane stretching vibrations and the symmetric stretching vibrations of the CH3, CH2, respectively; The appearance of the new adsorption peaks at about 1455 and 1375 cm−1 on the PP matrix may be caused by the CH3 out-of-plane bending vibrations and the symmetric bending vibrations of CH2, respectively. Compared to the spectrum of the original fiber, a strong adsorption peak at 1730 cm−1 can be observed, which characterizes the carbonyl group and caused by the stretching vibrations of carbonyl group of fatty acid esters, indicating that carbonyl has been grafted onto PP. The new characteristic absorption peak at 1150cm-1 was corresponded to the stretching vibrations of C—O and adsorption peaks at 1150cm-1~1180cm-1 and 1240cm-1~1270cm-1 was caused by the stretching vibrations of C—C—O—C. In combination with the vibration peak of carbonyl, it indicated that ester existed in the PP-g-LA and PP-g-BA matrix. A weak adsorption peak at about 720cm-1 in c was caused by the bending vibration of C—H in (CH2)n (n≥4), which indicated that branch chains of LA had been grafted onto PP.
Grafted PP films seems quite complicated at the adsorption peak of 1000cm-1~1500cm-1, due to the introduction of quaternary carbon ions after grafted, effects of carbonyl groups on the bending vibrations of methyl and the adsorption peak of C—O—C at 1000cm-1~1300cm-1.
Taken together, we can speculate that both monomer LA and BA have been grafted onto the virginal PP fibers.
3.2 Scanning electron microscopy (SEM) study
The surfaces of the virginal PP and the grafted PP films were examined by SEM, and the results are shown in Figure 2. The morphology of grafted PP is different significantly from that of virginal PP substrate. The grafted surface shows a markedly bumpy texture, while the virginal PP surface is very planar, which indicated that monomer LA and BA have been grafted onto the virginal PP fibers.
3.3 TG analysis of PP matrix fibers
Weight loss of virginal PP fiber and grafted fibers were measured at the heating rate of 10 °C /min under an atmosphere of dry nitrogen. According to the TGA curves of the original PP fiber and the grafted fiber PP-g-LA and PP-g-BA given in Figures 3 and 4, the grafted PP fibers showed an excellent thermal stability at a temperature up to 370 °C. As seen from the figure of TG and DTG, both PP-g-BA and PP-g-LA grafted fibers undergo two processes of thermal decomposition, corresponding to the decompositions of crylic acid grafted chains and original PP fibers, respectively. Grafted chains experienced decomposition at a temperature from 371.6 to 425 °C , with a peak at 400.9°C;At a temperature from 455.6 to 649.3°C, original PP fibers experienced decomposition.
3.4 DSC analysis of PP matrix fibers
The melting temperature Tm and the apparent enthalpies of melting, △Hf(fiber), were obtained from the maximum and the area of the melting peak, respectively. Similarly, the crystallization temperature (Tf) and crystallization enthalpy, △Hf(cys) were obtained from the cooling DSC diagrams. The apparent crystallinity, Wc(%), of the PP and the grafted PP were calculated by the following equation:
Wc(%)=△Hf(PP) /△Hf(cys)×100
where △Hf(cys) is the heat of fusion per gram of 100% crystalline PP, which was 209 J/g (Yin, 2001). Because crystallization of the grafted PP occurs in the PP portion, the crystallinity of PP portion in the grafted copolymer, △Hf(PP) can be expressed as the following:
△Hf(PP)=△Hf(fiber) /(1-α)
where α is the weight fraction of grafts in the grafted copolymer.
The melting and crystallization behaviors of the samples are shown in Figure 5.The Tm, △Hf(PP), △Hf(fiber) and Wc(%) obtained from DSC curves in Figure 5 are listed in Table 1. It is known from these data that enthalpies of melting of grafted PP fibers decreased ascribed to “dilution effects” of grafts and “destructive effects” of radiation reaction on crystal zone (Huang, 2004, PP. 71-74, Zhu, 2004). Grafting of LA and BA onto PP film reduces the heat of melting and increases the melting enthalpy of PP. Influence of Tm is ascribed to two aspects. 1, grafting reaction was processed in the crazing zone of PP or main PP chains of crystal deficiency zone, regularity of crystal zone of PP got worse after grafted, destroyed the inherent crystal zone, which lead to the reduction of Tm of grafted PP fibers; 2, grafted PP polymers formed a new crystal which have a different Tm from virginal PP fibers. When the melting point of grafted chains is lower than virginal PP or grafted chains can’t form crystal, melting point of grafted PP decreases compared to the virginal PP. On the contrary, it may increases. As seen from Table 1, the crystallinity and melting enthalpy of grafted PP fibers increased slightly compared to virginal PP.
3.5 Effects of monomer concentration on grafting level of PP
Figure 6 showed the effect of monomer (BA and LA) concentration on the grafting percentage. It can be seen that the grafting percentage increases initially with the concentration of the monomers when reaches a top value, and then decreases slightly. BA reached its top grafting level of 29.90% at the concentration of 7.5% while LA reached its top grafting level of 20.53% at the concentration of 10%. Grafting level is highly related to scavenging ability for the free radicals and diffusivity to PP substrate of monomers. It is easy to understand that more monomers will be impregnated into the matrix as the concentration of monomer is high. However, the amount of homopolymers increases with the monomer concentration, and the homopolymers have been removed in the extraction process. It can be deduced that all the active sites on the PP substrate can be grafted when the concentration of the monomer is high enough. The initial increase in the grafting level is caused by the increased availability of free radicals for the chain transfer to polymer backbone. But when the concentration of the monomer exceeds a value, the average molecular weight of the side chains is reduced as well as the diffusivity of monomers, and the degree of homopolymerization and viscosity of solutions are increased . Both of these result in the reduction of the grafting level.
3.6 Effects of cross linking reagent concentration on grafting level of PP
The influence of divinylbenzene (DVB) on the grafting degree is shown in Figure 7. The grafting degree increased initially and dramatically with the presence of DVB, reached a top value and then decreased. At the concentration of 2%, grafting levels of BA and LA reached a peak value of 20.53% and 21.64%, respectively. Cross linking reagent with two double bonds has higher activity compared to acrylate. With a low DVB concentration, the grafting chains to PP films may be mostly cross linking reagent but not acrylate, which leads to the reduction of grafting level; With a high enough DVB concentration, the degree of homopolymerization of monomer acrylates are dramatically increased, which inhibited the diffusion of monomers to free radicals and thus interfered with the process of grafting reaction.
4. Conclusions
1. Virginal and grafted PP fibers was investigated by IR, TG and DSC, and SEM, which showed that both LA and BA have been grafted onto PP.
2. The maximum degree of grafting BA was 20.53%, grafting percentage increased initially with the concentration of the monomer and cross linking reagent when reaching a top value, and then decreased, which indicated that excess higher or lower concentration of the monomer and cross linking reagent could lead to the reduction of grafting levels. The maximum degree of grafting LA was 29.90%, its grafting percentage was similar to BA, which indicated that whether excess higher or lower concentration of he monomer and cross linking reagent was unfavorable to grafting reaction.
References
Figure 1. IR spectra of virginal PP (a), PP-g-LA (b), and PP-g-BA (c).
(a) PP (b) PP-g-LA
(c) PP (d) PP-g-BA
Figure 2. SEM images of virginal PP (a), PP-g-LA (b), and PP-g-BA (c)
Figure 3. TG analysis of virginal PP (a), PP-g-LA (b), and PP-g-BA (c)
Figure 4.DTG analysis of virginal PP (a), PP-g-LA (b), and PP-g-BA (c)
Figure 5. DSC thermographs of virginal PP (a), PP-g-LA (b), and PP-g-BA (c)
Figure 6. Relation between monomer concentration and grafting level
Figure 7. Relation between cross linking reagent concentration and grafting level
Table 1. Related DSC parameters of virginal PP, PP-g-LA and PP-g-BA.
Samples and Grafting degree (%) Tm (℃) △Hf(fiber) (J/g) △Hf(PP) (J/g) Wc (%)
1 PP 163.8 88.36 88.36 42.28
2 PP-g-LA (15.75%) 162.7 79.27 94.08 45.01
3 PP-g-BA (15.88%) 163.4 77.79 90.14 43.13
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| 案例标题： |
棒状杆菌降解染料酸性红B条件优化 |
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| 原文： |
棒状杆菌降解染料酸性红B条件优化
摘要：利用正交设计法优化B菌株降解染料酸性红B的条件。研究了温度、摇床转数、接种量和载液量4个因素对B菌株酸性红B的脱色率的影响。研究结果表明，在这些因素中影响该菌株降解染料酸性红B的最主要因素为载液量，而其他三个因素对该菌株降解染料酸性红B影响较小。研究中得出B菌株最适降解条件为先在33℃、120 r/min的摇床培养14h之后转移到培养箱继续培养22h、接种量为4%、载液量为80mL（150mL锥形瓶）。
关键词：棒状杆菌，酸性红B，正交设计
偶氮染料是世界上最大的化工类染料[1]，常常应用于纺织印染和造纸印刷行业，使得这类废水具有排放量大且分布广泛等特点。国内许多工厂多采用絮凝、吸附及电解等物理化学法来处理，但这些方法存在着耗电量大、成本高和脱色效果不理想等问题。目前，微生物降解染料受到国内许多学者的关注[2~7]。多种微生物在厌氧或好氧条件下裂解偶氮染料分子，将其降解成为分子量较小的芳香族类物质，被进一步利用。通常这种偶氮染料分子的裂解反应进行速度很慢，而这些反应的加快将有利于技术的应用。本文选取棒状杆菌为研究对象，对该菌降解染料酸性红B的降解条件进行了优化，对该菌株在染料降解中的应用具有重要意义。
1 材料与方法
1.1 菌种
从天津市武清区印染厂沉淀污泥中分离并纯化得到一株降解效果很好的菌株，经鉴定命名为变异性棒状杆菌（Corynebacterium variabile，简称为B菌）。
1.2 培养基
驯化培养基：牛肉膏 3g，蛋白胨 10g，NaCl 5g，酸性红B 0.04g，pH值 7.2，0.10Mpa灭菌30min。
无机培养基：NaH2PO4 ·2H2O 0.5g，MgSO4·7H2O 0.2g，K2HPO4 0.5g，(NH4)2SO4 2g，CaCl2 0.1g，葡萄糖 10g,，酸性红B 0.04g，蒸馏水 1000mL。
酸性红B是商品级的染料，进行紫外扫描，得其最大吸收波长为515nm。
1.3 培养条件的确定
将14个150mL锥形瓶分为7组，每组2个作为对比样，将每个锥形瓶分别分装50mL无机培养基于0.05Mpa下灭菌20min。接入B菌株后将第一组直接放入33℃培养箱中进行培养，而其它6组先33℃ 120r/min 的摇床中培养，在培养12h后每隔2h取出一组锥形瓶转入培养箱中继续培养至脱色。
1.4 培养方法
在150mL锥形瓶中分装不同量的无机培养基，根据正交实验进行试验，将接种好B菌株的锥形瓶最佳培养条件下培养36h。
1.5 正交设计
选取培养温度、摇床转数，接种量和载液量等4个因素，每个因素选取3水平，正交设计助手软件中选L18（36）进行正交实验，测定在各条件下降解后的上清液的吸光度。根据正交实验结果和方差分析结果得出各因素对B菌株降解染料酸性红B影响的显著性大小和各因素最佳水平，从而确定出B菌株降解染料的最佳培养条件。各因素的实验取值见表1。
表1 酸性红B降解条件正交实验的影响因素和水平
Table 1 Factors and levels affected the degradation orthogonal design
水平号
(Level number) 影响因素(Factors)
A
温度(℃)
(Temperature) B
转速(r/min)
(Rotating speed) C
接种量(%)
(Inoculation size) D
载液量(mL)
(Liquid level)
1 28 90 2 20
2 33 120 4 50
3 38 150 6 80
1.6 测定方法
将培养至脱色的菌液取出离心去除细胞，取上清液在721型分光光度计波长515nm处测定降解前后酸性红B的吸光度。
按照如下的公式计算脱色率：
其中：A0：接菌后初始时刻的吸光度
At：培养36h的吸光度
2 结果与讨论
2.1 培养条件
从表2中可以看出，一直在培养箱或摇床中培养的菌株脱色效果并不好，而先在摇床中培养一段时间再转入培养箱中培养的B菌株脱色效果都还不错，在摇静时间比为14:22时的脱色率达到最大，之后再增加在摇床上的培养时间并不会提高其脱色率，反而使脱色率有所下降，表明在摇静时间比为14:22时最适宜B菌株的生长和染料酸性红B的降解。
表2 摇静时间的影响
Table 2 Effect of the time ratio of shaking and resting
摇静时间比
(Time ratio of shaking and resting) 0:36 12:24 14:22 16:20 20:16 24:12 36:0
脱色率（%）(Decolorization rate) 32.6 92.6 94.6 93.4 91.7 70.7 46.9
2.2不同降解条件对该菌株降解染料酸性红B的影响
按照正交设计助手要求将降解36h的实验结果绘制到表格中，利用该软件进行分析，得到如下表3。
表3 染料降解的正交实验结果表
Table 3 Results of orthogonal test degraded azo dye
所在列(Line) 1 2 3 4 5 6
因素 (Factors) 温度(Temperature) 转速 (Rotating speed) 接种量 (Inoculation size) 载液量 (Liquid level) 误差 (Error) 实验结果(Results)
实验1(Test1) 1 1 1 1 1 47.1
实验2(Test2) 1 2 2 2 2 95.5
实验3(Test3) 1 3 3 3 3 94.8
实验4(Test4) 2 1 1 2 2 81.2
实验5(Test5) 2 2 2 3 3 95.9
实验6(Test6) 2 3 3 1 1 96.5
实验7(Test7) 3 1 2 1 3 74.6
实验8(Test8) 3 2 3 2 1 95.2
实验9(Test9) 3 3 1 3 2 95.6
实验10(Test10) 1 1 3 3 2 95.7
实验11(Test11) 1 2 1 1 3 51.1
实验12(Test12) 1 3 2 2 1 95.7
实验13(Test13) 2 1 2 3 1 96.2
实验14(Test14) 2 2 3 1 2 96.0
实验15(Test15) 2 3 1 2 3 84.3
实验16(Test16) 3 1 3 2 3 96.7
实验17(Test17) 3 2 1 3 1 96.2
实验18(Test18) 3 3 2 1 2 62.2
均值1(Average1) 79.983 81.917 75.917 71.250 87.817
均值2(Average2) 91.683 88.317 86.683 91.433 87.700
均值3(Average3) 86.750 88.183 95.817 95.733 82.900
极差(Range) 11.700 6.400 19.900 24.483 4.917
图1 四因素影响趋势
Fig. 1 Effect trend of the four factors
对表3和表4进行分析，从表中R值（极差）和F比的大小可以看出各影响因素从大到小依次为：载液量（D）＞接种量（C）＞温度（A）＞转速（B）。其中前两个因素的R值和F比较大，可以认为对B菌株降解染料酸性红B影响较大，因此在使用该菌株进行实验时应特别注意严格控制这两个因素。另外两个因素温度和转速的R值和F比较小，可以认为对B菌株降解染料酸性红B的影响较小，即该菌株对这两个因素具有较广的适应范围。通过对因素影响趋势图（图1）的分析看出：B菌株降解染料酸性红B最适温度为33℃，最适转速为120r/min，最适接种量在6%左右，最适载液量为80mL,即A2B2C3D3。
表4 染料降解的正交实验结果方差表
Table 4 Variances of orthogonal test degraded azo dye
因素 (Factors) 偏差平方和 (Sum of squares of deviation from mean) 自由度 (Degree of freedom) F比 (F ratio) F临界值 (F critical value) 显著性(Significance)
温度 414.031 2 4.383 19.000
转速 160.498 2 1.699 19.000
接种量 1190.698 2 12.606 19.000
载液量 2050.581 2 21.710 19.000 *
误差 94.45 2
F0.05（2，2）=19.000
2.3验证实验
选择正交实验结果中最适的降解条件，对B菌株降解染料酸性红B能力进行验证研究，在此条件下重复3次，进行验证实验，结果见表5。
表5 对比实验结果
Table 5 Results of comparison test
工艺条件 实验号 脱色率（%）
A2B2C3D3 1 94.9
2 95
3 96.2
分析实验结果发现，与方差分析及因素影响趋势图的结果基本一致，在温度为33℃，转速为120r/min，接种量为6%，载液量为80mL时，B菌株对染料酸性红B的平均脱色率为95.4%，脱色率较高且具有可重复性，验证了所选降解条件的合理性。
3 结论
筛选出的棒状杆菌是具有较高染料降解活性的微生物，通过正交实验设计方法，优化了B菌株降解染料酸性红B的降解条件。实验结果表明：B菌株在摇静时间比为14:22时染料酸性红B的降解效果最好，可以达到94.6%的脱色率；在此培养方式下的最佳培养条件为：温度为33℃，转速为120r/min，接种量为6%，载液量为80mL；在优化培养条件下，脱色率在95%以上。
参考文献
[1] Yuzhu Fu, T.Viraraghanvan. Fungal decolorization of dye wastewaters: a review. Bioresource Technology, 2001,79:251~262.
[2] 郑平,环境微生物学,杭州:浙江大学出版社,2002,59.
[3] 钟文文. 絮凝剂产生菌的筛选及其培养条件的优化.西北农业学报, 2008,17(1):120~123.
[4] 董新娇,吴楚,林贤芬,等. 染料脱色菌群的分离及对红色偶氮染料的脱色研究.江西科学, 1999,17(4):220~224.
[5] 董新娇,吴楚,林贤芬,等. 染料脱色菌群的分离及对红色偶氮染料的脱色研究.江西科学, 1999,17(4):220~224.
[6] Chunlong Zhang,K.T. Valsaraj et al. Nutrient and surfactant enhancement for the biodegradation of chlorinated hydrocarbons in the wastewater from a Louisiana Superfund site. Journal of Hazardous Material,1998,62:4158.
[7] 张隆.酸性偶氮染料还原产物催化强化偶氮染料生物脱色.大连理工大学硕士学位论文.2007.
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Optimized Design of Acid red B for Degradation by Corynebacterium
Abstract
The optimized experimental parameters of degradation obtained with a four-factor at three-level orthogonal array experimental design L18(36) were temperature, rotation speed, inoculum size and liquid level by Corynebacterium variabile in the shaking bottle as 33℃,22h after shaking at the same temperature and 120 rpm for 14h, 4%, 80mL in 150mL triangle bottle, respectively. Among four factors, liquid level is paramount.
Keywords: Corynebacterium variabile, Acid Red B, Orthogonal design
1. Introduction
Azo dyes, as the mainly dyeing material in the world(Yuzhu,2001,PP.251-262),are ofren used in the colouring process of several textiles, dyestuff and paper-making products. Relatively recently it has been recognised that some azo dyes agents may bring a large amount of waste water, which flow abroad in aqueous solutions. The researches in the field have led to laboratory demonstration of the applicability of technique, and to industrial pilot plant and full-scale established technologies for treating effluents of dying factories. Dye wastewater is usually treated by physical- or chemical-treatment processes such as flocculation, absorption and electrolysis etc, by most factories in China, nevertheless, both physical and chemical methods have their shortcomings which incurs less decolorization, more electric power and thus high operating expenses. In recent years, there have been an intensive research focused on the degradation of dyes by microorganism in the world(Ping,2002,P.59,Wenwen,2008,PP.120-123,Xinjiao,1999,PP.220-224,Chunlong,1998,PP.41-58, Long,2007).In aerobic or anaerobic condition, azo dyes were likely degradated to low molecular aromatic structures which could be further used. The reaction rate of degradation was usually quite slow, and thus promotion of the reaction could be helpful to the application of these techniques. In the present paper, Corynebacterium variabile, as a microbial agent, was undertaken to investigate the degradation effect in Acid Red B and the experimental parameters of degradation were also optimized. Hence data obtained from these experiments would give some novelty in the application of dye degradation by this fungus.
2 Materials and methods
1.1 Fungus
Microorganism used in this study was separated and purified from sullage sample of printworks effluent contaminated sites in Wuqing District,Tianjin with a good effect of dye degradation, and was identified and named as Corynebacterium variabile, briefed as fungus B.
1.2 Medium
Domesticated medium: Beef grease 3g,Peptone 10g,Acid Red B 0.04g,pH 7.2,sterilized for 30 min under 0.10Mpa.
Inorganic medium: NaH2PO4 ·2H2O 0.5g,MgSO4·7H2O 0.2g,K2HPO4 0.5g,(NH4)2SO4 2g,CaCl2 0.1g,Glucose 10g,Acid Red B0.04g,Distilled water 1000ml.
Acid Red B powder was commercially available dye used without further purification. The maximum absorption wavelength was 515 nm in UV–vis measurements.
1.3 Culture condition confirmation
14 150ml taper flask was arranged for seven groups, each group 2 in order to compare. Every flask was filled with 50ml inorganic medium, sterilized for 20min under 0.05Mpa and then was added with fungus B. After that, the first group was incubated at 33℃ and the other six were incubated in the shaking bottle at the speed of 120r/min at 33℃ for 12 h, then every 2h,one group was transferred to incubator until decolorization.
1.4 Culture method
150ml taper flasks were filled with different dose inorganic medium respectively. Based on orthogonal array experimental design, flasks added with fungus B was incubated at the optimal condition for 36h.
1.5 Orthogonal design
To obtain the optimised experimental parameters, a four-factor at three-level orthogonal array experimental design L18(36) was adopted by Orthogonal Design Assistant and the absorbance of degradation in each test were measured. The four factors were temperature, rotation speed, inoculum size and liquid level. Based on the experimental results of the previous orthogonal design and ANOVA analysis, the optimal ranges for each factor and their degradation effection could be obtained, and speculated the optimal conditions for fungus B in the degradation of Acid Red B.The factors studied and the assignments of the corresponding levels are listed in Table 1.
Table 1 Assignments of the levels to factors in orthogonal design
Level Factors
A
Temperature (℃)
B
Rotating speed (r/min)
C
Inoculation size (%)
D
Liquid level (mL)
1 28 90 2 20
2 33 120 4 50
3 38 150 6 80
1.6 Measurement
The fungus solution incubated till decolorization was centrifuged to remove cells, and supernate was undertaken to determine the absorbance of Acid Red B before or after degradation by UV-vis measurements(spectrophotometer 731,China). Decolorization rate was defined as follows:
Where Ao is the initial absorbance combined with fungus B and At is the absorbance after incubated for 36h.
2. Results and discussions
2.1 Incubating condition
As seen in Table 2,efficiencyies of decolorization was not good when fungus was incubated always in incubator or shaking apparatus,however,when incubated first in shaking apparatus for some time, then transferred to incubator was all good. At a time ratio of 14:22(shaking /quiescence ),efficiency of decolorization was the highest and was not increased by adding the time in shaking apparatus, but decreased inversely. Therefore, time ratio of 14:22(shaking /quiescence ) was the optimal condition for growth of fungus and degradation of Acid Red B.
Table 2 Effect of the time ratio of shaking to resting
Time ratio of shaking to quiescence 0:36 12:24 14:22 16:20 20:16 24:12 36:0
Decolorization rate(%) 32.6 92.6 94.6 93.4 91.7 70.7 46.9
2.2 Effect of Acid Red B degradation by fungus B in different conditions
According to Orthogonal Design Assistant,18 tests were performed. The analytical results are listed in Table 3. The average of the decolorization rate in each test were calculated. The values of |kmax-kmin| and F in Table 3 and 4 indicate the effect of temperature, rotation speed, inoculum size and liquid level.The efficiency of these four factors were classified in the order of liquid level(D)>inoculun size(C)>temperature(A)>rotation speed(B). Thus, liquid level was the major factor affecting the decolorization rate, whilst inoculun size, temperature and rotation speed had a less obvious influence. More attention should be paid to liquid level and inoculun size two factors in the experiment. As seen in Fig.1, in order to obtain the maximum decolorization rate, temperature, rotation speed, inoculum size and liquid level were chosen as 33℃, 120r/min, 6%and 80mL, respectively, namely A2B2C3D3.
Table 3 The matrix associated with the analytical results
Line 1 2 3 4 5 6
Factors
Number Temperature (℃) Rotating speed(r/min) Inoculation size (%) Liquid level(mL) Error Results(%)
1 1 1 1 1 1 47.1
2 1 2 2 2 2 95.5
3 1 3 3 3 3 94.8
4 2 1 1 2 2 81.2
5 2 2 2 3 3 95.9
6 2 3 3 1 1 96.5
7 3 1 2 1 3 74.6
8 3 2 3 2 1 95.2
9 3 3 1 3 2 95.6
10 1 1 3 3 2 95.7
11 1 2 1 1 3 51.1
12 1 3 2 2 1 95.7
13 2 1 2 3 1 96.2
14 2 2 3 1 2 96.0
15 2 3 1 2 3 84.3
16 3 1 3 2 3 96.7
17 3 2 1 3 1 96.2
18 3 3 2 1 2 62.2
Average1 79.983 81.917 75.917 71.250 87.817
Average2 91.683 88.317 86.683 91.433 87.700
Average3 86.750 88.183 95.817 95.733 82.900
|kmax-kmin| 11.700 6.400 19.900 24.483 4.917
Fig. 1 Effect trend of the four factors
Table 4 Variances of orthogonal design test of azo dye degradation
Factors Sum of squares of deviation from mean Degree of freedom F ratio F critical value Significance
Temperature 414.031 2 4.383 19.000
Rotating speed 160.498 2 1.699 19.000
Inoculation size 1190.698 2 12.606 19.000
Liquid level 2050.581 2 21.710 19.000 *
error 94.45 2
F0.05(2,2)=19.000
2.3Validated experiment
According to the orthogonal design results,the optimized parameters of decorlorization were undertaken to validate the effect of acid red B degradation by fungus B. With three replicates, results were listed in the Table 5.As seen from Table 5,results were conformed to Table 4 and Fig.1 and the average decolorization rate was 95.4% under the optimized condition where temperature, rotation speed, inoculum size and liquid level were chosen as 33℃, 120r/min, 6%and 80mL, respectively. Decolorization rate was high and repeatable, which showed that the optimized condition was reasonable.
Table 5 Results of comparison test
Technology conditions Number Decolorization rate(%)
A2B2C3D3 1 94.9
2 95
3 96.2
3. Conclusions
Fungus B separated from sullage has strong degradation activity of dyes. Through orthogonal design, degradation condition of acid red B by fungus B was optimized. Results showed that at a time ratio of 14:22(shaking /quiescence), degradation efficiency of acid red B was best, and the decolorization was 94.6%;In this way, the optimized incubating parameters of temperature, rotation speed, inoculum size and liquid level were 33℃, 120r/min, 6%and 80mL, respectively, whilst the decolorization rate was above 95%.
References
Chunlong, Z., Valsaraj, K.T., et al.(1998). Nutrient and surfactant enhancement for the biodegradation of chlorinated hydrocarbons in the wastewater from a Louisiana Superfund site. Journal of Hazardous Material, 62:4158.
Long,Z.(2007). Enhanced biological decolourzation of azo dyes by products reduced from acid azo dye.Dissertation for the master degree in Dalian science and technology University.
Ping, Z.(2002).Environmental microbiology.Hangzhou:Zhejiang University press, 59.
Wenwen,Z.(2008). Screening of bioflocculant-producing strains and study on optimization of their cultural conditions.Acta Agriculturae Boreali-Occidentalis Sinica, 17(1):120~123.
Xinjiao,D.,Chu,W.,Xianfen,L.,et al.(1999). Isolation of decolorizing bacteria group and its decolorization of red azo dyes.Jiangxi Science, 17(4):220~224.
Yuzhu, F., Viraraghanvan, T. (2001). Fungal decolorization of dye wastewaters: a review. Bioresource Technology, 79:251~262. |
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| 案例标题： |
种群动态测量方法和新的衡量指标 |
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| 原文： |
摘要：研究种群动态用具体数字来描述具有一定难度，它受传粉方式、营养源、捕食者、病害和繁殖方式等多种因素影响。本文采用一种合适的同心圆样方法和新的种群散布指数进行种群动态研究。它主要用途有:① 同一地域不同年份年份的动态比较。② 不同区域同一种群优劣的比较。③ 同一群落中不同种群优势度比较。并提出公式的优缺点，探讨进一步优化措施，最终达到科学合理地研究种群动态这一难题。
关键词：衡量指标 同心圆样方法 种群散布指数 加权处理
1 引言
植物种群是动态变化的，对其研究具有一定的难度。植物一旦生存一般具不可移动性，它的繁殖又受外因和内因双重影响。植物种群指标评价体系中，植株所在样方位置显得悠关重要。目前研究种群动态主要考虑的是遗传结构、空间结构、年龄结构和大小结构，因未能充分结合样地具有局限性。种群统计学中种群统计方程，其数值偏重于数量上的变化，不能有效地预测种群未来发展的趋势。鉴于上述原因和本人多年观察结果，我提出了采用同心圆样方法进行采样和种群散布指数这一新的评价指标。此样方和散布指数能很好地结合，并结合每株植物在样地的位置，对种群未来走势进行科学地描述。 |
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| 译文： |
Abstract
It is tough to investigate the population dynamics through specific numbers, which is affected by pollination, nutrition source, predator, disease, propagation way, and so on. The paper adopts the method of appropriate concentric circle and new population dispersing index for population dynamics study. Its main purposes includes: ①Population dynamic comparison of same region in different years. ②Superior and inferior comparison of the same population in different regions. ③Predominance comparison of different population in the same community. Furthermore, The advantage and disadvantage of this formula was estimated and a suitable and scientific way was screened to solve the puzzle of observing population through measures of further optimization.
Keywords: Evaluation indexes, Concentric-circles quadrat method, Distribution index of population, Weighted processing
1.Introduction
Vegetation population is a dynamic process, and thus is hard to investigate. Plant usually can’t be transferred once it survives, and its propagation is interfered by both the external and the internal factors. In the evaluation systems of indexes on population, the sample site of the pl ant is crucial. Unable to be well combined with the sample site, recently, studies on population dynamics mainly concern the genetics structure, space structure, age structure and size structure, and thus have its limitation. Equation in the statistics of population dynamics, laying particular stress on changes on the quantity, can’t effectively anticipate the development trends of population. Dependent on all above is concerned and our observations for years, I postulated a concentric-circles quadrat method for sampling and a new evaluation index, distribution index of population. Therefore, quadrat can be well combined with distribution index, in combination with sample site of each plant as well, which could describe the future trends of population scientifically. |
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