Cyclic scheduling of pulp digesters with integrated heating tasks

This paper addresses a multistage batch plant scheduling problem under energy constraints. These reflect the limited availability of a thermal heating utility that is shared among parallel digesters of different capacities for the production of pulp. Depending on the processing sequence, more or less steam will be available for a given digester, which will affect the duration of its heating stage and the overall cycle time. Such integrated heating tasks resemble direct heat integration, which has been addressed through models based on generic frameworks for process representation (e.g., State-Task Network, Resource-Task Network, State-Sequence Network) and relying on a single time grid, either discrete or continuous. A new multiple time grid continuous-time model is now proposed where the complex energy constraints are derived from the higher level modeling framework that is Generalized Disjunctive Programming. The results show a considerable better performance compared to RTN discrete and continuous-time formulations, due to a substantially lower integrality gap and model size

Industry energy optimization: A case study in a biodiesel production site

This paper presents a case study of heat exchanger network (HEN) retrofit with the objective to reduce the utilities consumption in a biodiesel production process. Pinch analysis studies allow determining the minimum duty utilities as well the maximum of heat recovery. The existence of heat exchangers for heat recovery already running in the process causes a serious restriction for the implementation of grassroot HEN design based on pinch studies. Maintaining the existing HEN, a set of alternatives with additional heat exchangers was created and analysed using some industrial advice and selection criteria. The final proposed solution allows to increase the actual 18 % of recovery heat of the all heating needs of the process to 23 %, with an estimated annual saving in hot utility of 35 k(sic)/y

Short-Term scheduling of a polymer compounding plant

This paper addresses the optimal short-term scheduling of a three parallel production line plymer compounding plant, whose equipments require cleaning between product changeovers. A very effective user-friendly software tool was developed, which consists of a general scheduling model coupled with capabilities of Microsoft Excel for data handling and analysis. The scheduling model is based on a Resource Task Network discrete time formulation and leads to Mixed Integer Linear Programming problems. As outputs the user can access the optimal schedules for a number of different objectives

Performance indicators for reactive distillation design

A cost indicator for the design and multi-objective optimization of reactive distillation columns, designated capacity, was introduced in previous work by the authors. The question of this indicator’s effectiveness as a measure of the actual column cost, is herein investigated over a number of designs by comparing it with the value obtained by means of conventional costing procedures. The results show that the level of accuracy obtained when using capacity is satisfactory and certainly acceptable for a preliminary design stage

Analysis of processing systems involving reaction and distillation : the synthesis of ethyl acetate

The integration of reaction and separation into a single process unit, i. e., reactive destillation, may offer several advantages over conventional systems that use a reactor followed by a distillation column. In this paper we explore the operational characteristics of reactive distillation and highlight some of this potential benefits, using the production of ethyl acetate as an illustrative example. With this aim, the two types of system are compared employing different reactor types and a number of performance indicators, such as yield, conversion, purity, specific energy consumption and residence time. A sensitivity analysis is carried out on some variables and parameters, in order to explore and define the distillation columns operating conditions. As expected, results point to a clear advantage of reactive distillation allowing for the azeotrope to be surpassed and for the overcoming of chemical equilibrium, favouring an increase in conversion and product purity, along with reduced operating costs

An Evolutionary No Man’s Land and Reply from L. G. Harshman and A. A. Hoffmann

The gap between evolutionary studies in laboratory versus natural populations is a persistent problem

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: a contribution to assess CCA toxicity

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment. In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO3) and arsenic pentoxide (As2O5) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As2O5 induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As2O5. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.publishe

Seasonal effects on HPLC-DAD-UV and UPLC-ESI-MS fingerprints and analgesic activities of vernonia condensata baker extracts

Vernonia condensata Baker leaves have different uses in Brazilian folk medicine, including as analgesic and anti-inflammatory agents. The purpose of this study was to evaluate the seasonal effects on their high performance liquid chromatography with a diode array detector (HPLC-DAD-UV) and ultra-performance liquid chromatography coupled to a mass spectrometer with an electrospray interface (UPLC-ESI-MS) fingerprints, as well as their analgesic activities in mice. There were significant seasonal effects on the relative abundances of the metabolites of the V. condensate leaves as well as on their activities. Analgesic activities in the writhing test were observed with the polar fraction of the leaf extracts collected in autumn, winter and summer (400 mg kg(-1)); and with the intermediate fraction of leaves collected in autumn (25 and 400 mg kg(-1)) and in the summer (100 mg kg(-1)). In conclusion, the results confirm peripherally-mediated anti-inflammatory and analgesic activities for V. condensata leaves and suggest that these are influenced by the harvesting season. N-oxides alkaloids as well as vernonioside play important roles in determining this activity262350358CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFundacao Araucari

Can different stages of leprosy treatment influence the profile of oral health? Oral status in leprosy

The aim of study was to evaluate the oral health status, salivary flow and halitosis among individuals diagnosed with leprosy as compared with healthy subjects. A sample of 160 individuals was allocated into four groups, as follows: (G1) individuals with complete leprosy treatment; (G2) individuals diagnosed with leprosy and under multi-drug therapy; (G3) individuals diagnosed with leprosy not yet under treatment; and (G4) healthy individuals. Then individuals were submitted to periodontal clinical examination (visible plaque index, bleeding index, depth of probing and clinical attachment level); DMFT index (decayed-missing-filled teeth index); evaluation of salivary flow and halitosis using a halimeter equipment (Interscan Corp, Chatsworth, CA, USA). The data were analyzed using Kruskal-Wallis and chi-square tests. The mean DMFT was found to be higher than 6.6, which is considered very high, with no significant difference between groups (P>0.05). As for salivary flow, 76.2% of the subjects presented normal flow rates, while 10% and 13.7% showed low and very low salivary flow rates, respectively, with hyposalivation being mostly observed in Groups 1 and 2. The highest prevalence of noticeable odor was found in healthy individuals (G4), and the most prevalent periodontal diagnosis was gingivitis (63.1%) in Group 3 (individuals with leprosy not yet under multi-drug therapy) followed by periodontitis (25%) in Group 1 (individuals who had completed leprosy treatment). It was observed that individuals with a history of leprosy present poor oral health similar to that of systemically healthy individuals