关于正负相间方幂和中因子p的指数

研究一类正负相间方幂和中素数因子p的指数问题,将方幂和中因子指数转化为由n,r,x和d组成代数式中因子个数计算.设n=pam,p|m,素数p>7,给出了正负相间方幂和中因(-1)k(x+dk)r,d=ps+1.子p的指数:D= 2n-1k=0     

特殊度条件下有向图的最大有向割

对于整数k,l≥0,用D(k,l)表示一类有向图的集合,这类图的每个顶点要么入度不超过k要么出度不超过l.研究了度条件下有向图中的最大有向割问题,目的是确定图类D(k,l)中有向图的最大有向割包含的弧的条数.对于包含m条弧的有向图,通过分析图的结构,采用数学归纳法,得到(1)若D∈D(2,3)∪D(3,2),则存在至少包含2m/7条弧的有向割;(2)设D∈D(k,k),若存在顶点集的一个二部划分(X,Y),使得X中点的入度与Y中点的出度都不超过k,并且起点在X中终点在Y中的弧的集合的导出图的基础图不含圈,则存在至少包含(1/4+1/(8k+4))m条弧的有向割.     

捻制系数快速求解与组股钢丝直径估算

研究钢丝绳捻制中捻距倍数k与捻制系数m的关系,当k和同层等直径股(钢丝)根数n确定时,m满足确定的一元四次方程。采用换元法,视m和n为定值,k满足一元二次方程,给出k的解析表达式。以n=17求k=8.500时的mk为例,介绍用Excel表计算m的方法,给出数据计算结果。研究m和k的分布特征,通过数字拟合,得出m拟合值与k值简洁的关系式,该关系式计算结果和精确求解结果误差很小,可用于快速求解。提供组股外层钢丝直径估算表用于钢丝绳工艺设计。     

关于正负相间方幂和中因子7的指数

设n=7^am,7不整除m,给出正负相间方幂和中因子7的指数2n-1∑k=0(-1)^k(x dk)^T,d=7s 1。     

k-free数与其逆的差

运用Kloosterman和、特征和以及三角和的一些基本性质和估计得到了k-free数与其逆的差的一个渐近公式.并且证明了:当k≥2,m≥2,n2,n∈N,k∈N,m∈N,ε0时,M(n,m;k)=2φ(n)nm/ζ2(k)(m+1)(m+2)+O(2mnm+1/2+2/(k+1)+2εd(n)σ-1/2(n)σ(n)).特别是当k=2时,有无平方因子数与其逆的差:M(n,m;2)=72φ(n)nm/π4(m+1)(m+2)+O(2mnm+1/2+2/(k+1)+2εd(n)σ-1/2(n)σ(n).此处的d(n)表示因数函数,(n)表示欧拉函数.     

关于指数Diophantine方程x^2＋2^（2m）=y^n

运用Lucas数本原素因数存在性的结果讨论方程x^2＋2^2m=y^n的正整数解（x,y,m,n）,证明了该方程仅有正整数解（x,y,m,n）=（2^（n-1）/2,2^r（rs-1）/2,s）和（2^3k.11,2^2k.5,3k＋1,3）适合n〉2,其中r和s是适合s〉2的正奇数,k是非负整数.     

关于模N的原根的分布

设模n≥3存在原根,对任一原根1≤a≤n-1,且(a,n)=1,显然存在唯一原根1≤(-a)≤n-1,使得a(-a)≡1(mod n),对给定的正整数1≤k≤n,且(k,n)=1及实数0＜δ≤1,研究了模n的原根a与它的逆(-a)及整除性,并给出关于(n∑a=1|a-(-a)|≤δna∈A k|a (-a))min(| a-(-a)|,| n a-(-a)|)较强的渐近公式.     

平版印刷产品中VOC含量测量不确定度分析与评估

根据平版印刷产品中挥发性有机化合物(VOC)含量的测试方法,研究了对测试结果的各种影响因素,详细叙述了挥发性有机化合物含量测量不确定度评定的方法,并计算了影响测量结果的各个不确定度分量。结果表明:当教材封面中甲苯残留量为0.36 m g/m2时,其合成标准不确定度为0.0176 m g/m2,扩展不确定度为0.035 mg/m2(P=95%,k=2)。     

脂肪酶催化醇解制备富含n-3 PUFAs的甘油酯

n-3 PUFAs具有多种生理活性。以鱼油为原料，采用脂肪酶催化醇解法对其中的n-3 PUFAs进行富集，得到富含n-3 PUFAs的甘油酯。结果表明：来自米曲霉的脂肪酶Eversa Transform 2.0(ET 2.0)对n-3 PUFAs表现出良好的醇解特异性。通过单因素实验确定最佳工艺条件为：甲醇体积分数40%,m甲醇∶m鱼油=1.6∶1，温度35℃，脂肪酶添加量4%，反应时间2 h。在此条件下，鱼油甘油酯中n-3 PUFAs的含量从39.88%上升至67.87%,EPA和DHA的含量从36.61%上升至65.22%,n-3 PUFAs的得率为56.33%。脂肪酶在最佳反应条件下对不同底物的富集效果是：金枪鱼油甘油酯中n-3 PUFAs的含量从38.81%上升到61.35%，藻油甘油酯中n-3 PUFAs的含量从45.96%上升到64.09%。上述方法获得的富含n-3PUFAs甘油酯在食品和制药行业有很大的应用潜力。     

酒量论安全

一般人每人每天摄入的酒精应以每kg体重1m g为限,即为每日饮酒安全量。这个量可以用一个简单的公式进行计算。每日饮酒的安全量(m l)=体重(kg)/0.8×酒的度数。以50kg体重的人为例,可计算出每天饮用各类酒的安全量(限量):白酒38°低度酒约165m l;45°中度酒约140m l;60°高度酒     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press     

INFOPRINT 2014 was Successfully Held in Dongguan

Sponsored by Printing and Printing Equipment Industries Association of China （PEIAC） and organized by Print China magazine, the Seventeenth Beijing International Printing Information Conference （INFOPRINT 2014） was successfully held on 11th Dec. 2014 at Dongguan Exhibition International Hotel.