Plant cell culture technologies: A promising alternatives to produce high-value secondary metabolites

Plants have been used for its medicinal values since ancient time. The medicinal properties of plants are based on their phytochemical constituent particularly secondary metabolites which are produced in low amounts by plants. Secondary metabolites have been used as medicines, flavors, colors, and fragrances. In recent time, these natural compounds are gaining enormous attention in pharmaceutical, cosmetics, and nutraceutical industries and are regarded economically valuable products. The production of plant secondary metabolites in plant is largely dependent on the plant species, environmental factors and geographical regions. In addition, the main challenges in their mass production is reported to be the quality and quantity issues during their synthesis. Therefore, enthusiasm has grown for increasing the production of secondary metabolites by employing in vitro plant cell culture technology and bioengineering methods. Such technological advancement, has led to production of a huge number of medicinal herbs and high-value secondary metabolites that are mostly used in pharmaceuticals, cosmetics and nutraceuticals industries. The current mini-review article focuses on applications of plant cell culture system for the production secondary metabolites and recent techniques used to improve metabolite contents. Furthermore, our review emphasizes safety issues of plant cell culture derived products.     

Convergent synthesis of the IJKLM-ring part of ciguatoxin CTX3C

Convergent synthesis of the IJKLM-ring part (2) of ciguatoxin CTX3C has been achieved from the I-ring and the L-ring parts (4 and 5) in total eight steps in 27% overall yield. The carbanion derived from 4, stabilized by a dimethyldithioacetal S-oxide group, was readily reacted with aldehyde 5 to give an adduct, which was facilely transformed into the corresponding α,ε-dihydroxy ketone 3. The JK-ring formation from 3 under reductive conditions followed by oxidative M-ring cyclization efficiently led to the pentacyclic ether 2. Improved synthesis of 6, a synthetic intermediate for 4, was also established.     

Oxidations by copper metalloenzymes and some biomimetic approaches

This paper illustrates the various aspects of the reactivity of the Cu(II)–Cu(I) system in biological systems, with one example of an enzymatic reaction in which Cu(II) alone is oxidizing enough to carry out the reaction (superoxide dismutase), one example in which a Cu(II)-bound peroxo intermediate is the active species (tyrosinase) and the examples of galactose oxidase and copper amine oxidases in which Cu(II) is associated with a redox active organic cofactor. In some cases, we will show some illustrations of biomimetic approaches developed in our laboratories, aimed at a better understanding of reaction mechanisms and at an original design of new catalysts with potential applications in synthetic chemistry. Some comments are given concerning the respective features of copper and iron.     

Tire compaction capacity rating on non-standard soil

Tire Compaction Capacity rating system with its CC index was evolved to support the choice of proper tires for off-road vehicles or machines operating on crop producing land with aim to prevent harmful compaction of the ground. This system, fundamentally presented in the Journal of Terramechanics, Vol. 52/2014, is based on a great number of laboratory compaction tests in common clay–loam soil (here marked as standard soil). The presented article deals especially with more accurate application of numerical rating to sandy and clay soils (very different grain size) under the designation equivalent Compaction Capacity (eCC) index, however, is applicable to an arbitrary soil type. The features and practical use of eCC rating are explained and discussed in this technical note.     

PERMANENCE OF AN IMPULSIVE PREDATOR-PREY SYSTEM WITH MUTUAL INTERFERENCE AND CROWLEY-MARTIN RESPONSE FUNCTION

Let $S(R^2)$ be the class of all infinitely differential functions which, as well as their derivatives, are rapidly decreasing on $R^2$. Here we define a kind of semi-norms which is equivalent to the usual family of semi-norms on the Schwartz space $S(R^2)$.     

Techno-Economic Analysis of FiWi Access Networks Based on 802.11ac WLAN and NG-PON2 Networks

In this article, techno-economic analysis of a fiber-wireless access network is presented. With high bandwidth capacity of the gigabit passive optical network and with cost-effectiveness of very high throughput 802.11ac wireless local area networks that enable user mobility in the wireless segment, fiber-wireless access networks can be considered as an alternative to the fiber-to-the-home architecture for next generation access networks. Analysis based on the proposed scenario here, shows that a fiber-wireless access network is a more cost-effective solution in densely populated areas, but with some introduced improvements, even other geotypes can be considered as a commercially-viable solution.     

Labor market underrepresentation results in minority discrimination: A dynamic hiring model with employer learning

This paper develops a dynamic model of minority labor market discrimination. Employers repeatedly decide to hire either minority or majority job candidates whose productivities are unobservable beforehand. Hiring decisions are based on productivity expectations derived from the observable productivity of employers’ previously hired workers. If employers have fewer minority workers initially—a plausible assumption for (numerical) minorities—they discriminate against minority workers over time. Discrimination results from more dispersed minority expectations across the employer population and stronger effects of additional productivity observations on minority expectations. Both effects are a direct consequence of the minority’s initial underrepresentation in firms. I demonstrate the emergence of minority discrimination formally in a two-period hiring model and show simulation results for longer time frames.     

免费更换策略下耐用品垄断厂商的定价研究

耐用品厂商向消费者提供一定时间期限的免费更换服务已成为一种市场销售策略.免费更换服务期限和所需的更换成本又影响着耐用品的销售价格和销售量.针对耐用品厂商提供免费更换服务的情况,通过建立动态决策模型利用最优控制理论研究垄断厂商有关耐用品最优定价和免费更换服务期限等问题.研究得到:免费更换服务期越长,耐用品最优销售价格越高,而耐用品最优销售量越低;在以最优价格销售耐用品时,免费更换服务期和更换成本均与产品耐用度成正比例关系.     

Exterior statistics based boundary conditions for representative volume elements of elastic composites

Statistically equivalent representative volume elements or SERVEs are representations of the microstructure that are used for micromechanical simulations to generate homogenized material constitutive responses and properties (Swaminathan et al., 2006a, Ghosh, 2011). Typically, a SERVE is generated from the parent microstructure as a statistically equivalent region, whose size is determined from the requirements of convergence of macroscopic properties. Standard boundary conditions, such as affine transformation-based displacement boundary conditions (ATDBCs), uniform traction boundary conditions (UTBCs) or periodic boundary conditions (PBCs) are conventionally applied on the SERVE boundary for micromechanical simulations. However, when the microstructure is characterized by arbitrary, nonuniform distributions of heterogeneities, these simple boundary conditions do not represent the effect of regions exterior to the SERVE. Improper boundary conditions can result in significantly larger than optimal SERVE domains, needed for converged properties. In an attempt to overcome the limitations of the conventional boundary conditions on the SERVE, this paper explores the effect of boundary conditions that incorporate the statistics of the exterior region on the SERVE of elastic composites. Using Green's function based interaction kernels, coupled with statistical functions of the microstructural characteristics like one-point and two-point correlation functions, a novel exterior statistics-based boundary condition or ESBC is derived for the SERVE. The advantages of the ESBC are established by comparing with results of simulations using conventional boundary conditions. Results of the SERVE simulations subjected to ESBCs are also compared with those from other popular methods like statistical volume element (SVE) and weighted statistical volume element (WSVE). The proposed ESBCs offer significant advantages over other methods in the SERVE-based analysis of heterogeneous materials.     

The capital cost of holding inventory with stochastically mean-reverting purchase price

Most models of inventory control assume that the per unit purchase price is constant. The capital cost of holding inventory can then be taken into account by adding a fixed interest rate, r, times the purchase price, C, to the out-of pocket holding cost. However, it is not uncommon that the purchase price varies over time. How the capital cost then should be calculated is the focus of the present paper. The paper studies the common single-item inventory model with a fixed set-up cost and assumes that the stochastic purchase price follows the mean-reverting Ornstein–Uhlenbeck process. Methods for computing an adjusted interest rate, r, are suggested along with modifications of well-known heuristics and formulas for lot-sizing. Simulation tests, where the optimal policy has been compared to policies obtained using modified versions of the Silver–Meal method, the Part Period algorithm and the EOQ formula, suggest that r should be estimated as the sum of the unadjusted interest rate and the average expected purchase price decrease, measured over a period between 1/3 and 2/3 of the length of the order cycle.