We present a detailed survey of software packages for two-dimensional cutting stock problems. Cut... more We present a detailed survey of software packages for two-dimensional cutting stock problems. Cutting stock problems (CSP) may involve a variety of objectives and constraints, which directly depend on technological and organizational parameters of each company. Therefore, this comparison was based on some of the packages' main features, the most relevant to the problem's context.
Enzyme catalysis in organic solvents is a valuable tool for the synthesis of a number of importan... more Enzyme catalysis in organic solvents is a valuable tool for the synthesis of a number of important chiral compounds. However, their usually low activity in these applications is a major drawback which hampers their potential. To overcome this, research groups around the world have successfully employed a variety of additives to protect enzyme catalysts from the detrimental effects of dehydration (mostly by freeze-drying, a required step prior to introducing the catalyst to organic solvents) and subsequent exposure to organic media. Modified cyclodextrins are among the most successful additives employed for this purpose. However, to maximize their constructive effect it is necessary to determine how these cyclic macromolecules enhance enzyme catalytic activity as well as the enantioselectivity. Our data suggests that MCD activates the serine protease subtilisin C. predominantly by preserving the enzyme structure. Supporting data include the facts that: (a) MCD must be co-dissolved with the enzyme in buffer prior to lyophilization; (b) formation of inclusion complexes is excluded from contributing to the activation because no increase in enantioselectivity or in activity was observed when MCD was added directly to the enzyme-organic solvent mixture; (c) MCD works at an optimum concentration, after which a decrease in enzyme activity is observed; (d) removal of the additive by washing steps only causes minor activity decreases; (e) co-lyophilization of a lipase was also found to increase its enantioselectivity towards the opposite enantiomer than subtilisin. These data are irreconcilable with a mechanism of activation that involves the formation of inclusion complexes between the additive, the substrates and the products, which has been proposed to contribute to the activation of a lipase.
In this paper, an integer programming model for two-dimensional cutting stock problems is propose... more In this paper, an integer programming model for two-dimensional cutting stock problems is proposed. In the problems addressed, it is intended to cut a set of small rectangular items of given sizes from a set of larger rectangular plates in such a way that the total number of used plates is minimized.
Asia-pacific Journal of Operational Research, 2011
This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage ... more This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage and three-stage two-dimensional guillotine bin packing and cutting stock problems. A solution is represented as a sequence of items which are packed into existing or new stacks, shelves or bins according to previously defined criteria. Moreover, SNS comprises three random neighborhood structures based on modifying the current
In this paper, an integer programming model for two-dimensional cutting stock problems is propose... more In this paper, an integer programming model for two-dimensional cutting stock problems is proposed. In the problems addressed, it is intended to cut a set of small rectangular items of given sizes from a set of larger rectangular plates in such a way that the total number of used plates is minimized.
Asia-pacific Journal of Operational Research, 2011
This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage ... more This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage and three-stage two-dimensional guillotine bin packing and cutting stock problems. A solution is represented as a sequence of items which are packed into existing or new stacks, shelves or bins according to previously defined criteria. Moreover, SNS comprises three random neighborhood structures based on modifying the current
We present a detailed survey of software packages for two-dimensional cutting stock problems. Cut... more We present a detailed survey of software packages for two-dimensional cutting stock problems. Cutting stock problems (CSP) may involve a variety of objectives and constraints, which directly depend on technological and organizational parameters of each company. Therefore, this comparison was based on some of the packages' main features, the most relevant to the problem's context.
Enzyme catalysis in organic solvents is a valuable tool for the synthesis of a number of importan... more Enzyme catalysis in organic solvents is a valuable tool for the synthesis of a number of important chiral compounds. However, their usually low activity in these applications is a major drawback which hampers their potential. To overcome this, research groups around the world have successfully employed a variety of additives to protect enzyme catalysts from the detrimental effects of dehydration (mostly by freeze-drying, a required step prior to introducing the catalyst to organic solvents) and subsequent exposure to organic media. Modified cyclodextrins are among the most successful additives employed for this purpose. However, to maximize their constructive effect it is necessary to determine how these cyclic macromolecules enhance enzyme catalytic activity as well as the enantioselectivity. Our data suggests that MCD activates the serine protease subtilisin C. predominantly by preserving the enzyme structure. Supporting data include the facts that: (a) MCD must be co-dissolved with the enzyme in buffer prior to lyophilization; (b) formation of inclusion complexes is excluded from contributing to the activation because no increase in enantioselectivity or in activity was observed when MCD was added directly to the enzyme-organic solvent mixture; (c) MCD works at an optimum concentration, after which a decrease in enzyme activity is observed; (d) removal of the additive by washing steps only causes minor activity decreases; (e) co-lyophilization of a lipase was also found to increase its enantioselectivity towards the opposite enantiomer than subtilisin. These data are irreconcilable with a mechanism of activation that involves the formation of inclusion complexes between the additive, the substrates and the products, which has been proposed to contribute to the activation of a lipase.
In this paper, an integer programming model for two-dimensional cutting stock problems is propose... more In this paper, an integer programming model for two-dimensional cutting stock problems is proposed. In the problems addressed, it is intended to cut a set of small rectangular items of given sizes from a set of larger rectangular plates in such a way that the total number of used plates is minimized.
Asia-pacific Journal of Operational Research, 2011
This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage ... more This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage and three-stage two-dimensional guillotine bin packing and cutting stock problems. A solution is represented as a sequence of items which are packed into existing or new stacks, shelves or bins according to previously defined criteria. Moreover, SNS comprises three random neighborhood structures based on modifying the current
In this paper, an integer programming model for two-dimensional cutting stock problems is propose... more In this paper, an integer programming model for two-dimensional cutting stock problems is proposed. In the problems addressed, it is intended to cut a set of small rectangular items of given sizes from a set of larger rectangular plates in such a way that the total number of used plates is minimized.
Asia-pacific Journal of Operational Research, 2011
This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage ... more This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage and three-stage two-dimensional guillotine bin packing and cutting stock problems. A solution is represented as a sequence of items which are packed into existing or new stacks, shelves or bins according to previously defined criteria. Moreover, SNS comprises three random neighborhood structures based on modifying the current
Uploads
Papers by Elsa Silva