树脂吸附法分离纯化桑叶总黄酮——（Ⅱ）动态法分离桑叶总黄酮的工艺条件及数学模拟

考察了H103树脂固定床吸附分离桑叶总黄酮的工艺参数,并对吸附工艺进行了数学模拟和比较.实验结果表明,H103树脂固定床吸附分离桑叶总黄酮在上样浓度6.05mg/mL时,以9mL/min上样,吸附完全后用60%乙醇以4.5mL/min流速洗脱,桑叶总黄酮产品的回收率为90.57%,纯度为76.33%,建立的固定床吸附模型为预测固定床吸附桑叶水提液中桑叶黄酮达到穿透点时间及固定床吸附容量提供了准确、快捷的方法.     

THE STRUCTURE OF ORTHOGONAL GROUPS OVER ARBITRARY COMMUTATIVE RINGS

Let R be an arbitrary commutative ring, and n an integer≥3. It is proved for any ideal J of R thatEO_(2n)(R, J)=[EO_(2n)(R), EO_(2n)(J)]=[EO_(2n)(R), EO_(2n)(R, J)]=[EO_(2n)(R), O_(2n)(R,J)]=[O_(2n)(R), EO_(2n)(R,J)].In particular, EO_(2n)(R, J) is a normal subgroupof O_(2n)(R). Furthermore, the problem of normal subgroups of O_(2n)(R) has an affirmative solution if and only if aR∩ Ann(2)=α~2 Ann(2) for each a in R. In particular, if 2 is not a zero divisor in R, then the problem of normal subgroups of O_(2n)(R) has an affirmative solution     

Amplified analysis of DNA by the autonomous assembly of polymers consisting of DNAzyme wires

A systematic study of the amplified optical detection of DNA by Mg(2+)-dependent DNAzyme subunits is described. The use of two DNAzyme subunits and the respective fluorophore/quencher-modified substrate allows the detection of the target DNA with a sensitivity corresponding to 1 × 10(-9) M. The use of two functional hairpin structures that include the DNAzyme subunits in a caged, inactive configuration leads, in the presence of the target DNA, to the opening of one of the hairpins and to the activation of an autonomous cross-opening process of the two hairpins, which affords polymer DNA wires consisting of the Mg(2+)-dependent DNAzyme subunits. This amplification paradigm leads to the analysis of the target DNA with a sensitivity corresponding to 1 × 10(-14) M. The amplification mixture composed of the two hairpins can be implemented as a versatile sensing platform for analyzing any gene in the presence of the appropriate hairpin probe. This is exemplified with the detection of the BRCA1 oncogene.     

ISOMORPHISMS OF STABLE STEINBERG GROUPS

In [2] the author discussed the isomorphisms between two unstable Steinberg groups $St_m(A)$ and $St_n(R)$ over commutative rings. The aim,of the present paper is to determine the isomorphisms between two stable Steinberg groups St(A) and St(R), and the isomorphisms between the corresponding stable linear groups.     

树脂吸附法分离纯化桑叶总黄酮(Ⅰ)H103树脂对桑叶水提液中总黄酮的吸附性能

采用大孔吸附树脂法从桑叶水提液中分离黄酮类化合物。通过比较10种大孔吸附树脂对桑叶水提液中总黄酮的吸附特性及机理,发现H103树脂对桑叶总黄酮吸附量大、洗脱容易、吸附速度快,是一种良好的桑叶总黄酮吸附剂。实验表明,H103树脂吸附桑叶黄酮的适宜上样浓度为6.05mg/mL,吸附动力学符合Bangham模型,吸附过程符合内扩散模型。     

Inventory and shelf-space optimization for fresh produce with expiration date under freshness-and-stock-dependent demand rate

It is well documented that the demand for fresh produce, to a great extent, depends on how fresh it is and an increase in shelf space for displayed stocks may induce more purchase of the produce. However, relatively little attention has been paid to the effect of expiration date despite the fact that produce deteriorates over time and expiration dates are often an important factor in consumers’ purchase decision. In this paper, we propose an economic order quantity model in which we explicitly specify the demand for fresh produce to be a function of its freshness-expiration date and displayed volume. With the demand being freshness-and-stock dependent, it may be profitable to maintain high stock level at the end of the replenishment cycle. Hence, we relax the traditional assumption of zero ending inventory to non-zero ending inventory. Consequently, the objective here is to determine the optimal level of shelf space size, replenishment cycle time, and/or ending inventory level in an effort of maximizing the total annual profit. We found that the total annual profit is strictly pseudo-concave with regard to the three decision variables, which simplifies the search for the global solution to a local optimal. Numerical examples are then presented to highlight the theoretical implications and managerial insights.