A tri-level optimization model for inventory control with uncertain demand and lead time

We propose an inventory control model for an uncapacitated warehouse in a manufacturing facility under demand and lead time uncertainty. The objective is to make ordering decisions to minimize the total system cost. We introduce a two-stage tri-level optimization model with a rolling horizon to address the uncertain demand and lead time regardless of their underlying distributions. In addition, an exact algorithm is designed to solve the model. We compare this model in a case study with three decision-making strategies: optimistic, moderate, and pessimistic. Our computational results suggest that the performances of these models are either consistently inferior or highly sensitive to cost parameters (such as holding cost and shortage cost), whereas the new tri-level optimization model almost always results in the lowest total cost in all parameter settings

A Bayesian Approach to The Assessment of Fuel Composition Variability Effects on Grate-bed Biomass Combustion

Combustion systems are the most energy-intensive facilities in the world. They are responsible for releasing the majority of the greenhouse gases (GHG) and NOx into the earth’s atmosphere. Biomass is the only renewable energy source consisting of fixed carbon elements which can be substituted for fossil fuels in combustion systems. The main distinction between biomass and fossil fuel combustion is fewer pollutant emissions of biomass combustion, as well as, biomass combustion’s lower price and simpler storage facility. So far, direct combustion of the solid biomass is the most popular method, both thermally and economically, among all various bioenergy systems, which is due to the price of biofuels process cost. Grate firing technology is of interest to burn solid biomass because it has less sensitivity to feed composition and size, which shows the excellent potential of this technology. However, owing to the intrinsic composition variability of biomass, there are still uncontrolled deflections associated with biomass combustors operations. This study is an effort to quantify the overall impact of fuel compositions variability on moving bed biomass combustion, which will facilitate the understanding of biomass combustion. Randomly selected biomass pellets were individually investigated via a Thermogravimetric Analysis (TGA) to specify the fuel compositions; moisture, volatile, char, and ash. This data, together with the predefined fuel composition provided by fuel supplier are utilized to train a model using a Bayesian approach to populate our measured data. Simultaneously, a 1D transient numerical model of moving bed biomass combustion is deliberately developed corresponding to the research goals. The model iteratively runs with distributed fuel composition made by the Bayesian data generator and simulates the combustor under uncertain conditions. The comprehensive thermo-economic and environmental analysis of the biomass boiler operated with the three most common biomass types was conducted. Specifically, this includes biomass pellets, wood waste, and municipal solid waste and through this research showed that biomass pellets are the most efficient in terms of thermal operation and financial revenue. An experiment-based approach to the composition uncertainty impact of biomass pellets and bamboo chips on moving bed combustors were also practiced. While a notable heat flux deviation from mean operation conditions was observed for both, the pelletizing helped pellets to limit the level of uncertainty to a satisfying degree. Higher char content can limit the combustion uncertainty to a strong extent, while the moisture content was found to be the main contributor to the level of uncertainty. As well, NOx emission arising from biomass combustion fluctuated up to 17% due to composition variability. Finally, combustor operations under more reliable input data via the Bayesian data generator showed a remarkable system deviation from that of predefined input conditions. Overlooking the fuel compositions variability caused an overestimation of heat generation of up to 8.5%. Moreover, a notable amount of unburned biomass particles was sent to an ash bin, which is not in line with biomass harvesting sustainability. To avoid this in the future, the system must be regulated to correspond to the fuel compositions offered by the Bayesian model

Soil Moisture Studies with Four Varieties of Bermudagrass

Agronom

Novel Carboxymethyl cellulose-based hydrogel with core-shell Fe3O4@SiO2 nanoparticles for quercetin delivery

A nanocomposite composed of carboxymethyl cellulose (CMC) and core–shell nanoparticles of Fe3O4@SiO2 was prepared as a pH-responsive nanocarrier for quercetin (QC) delivery. The nanoparticles were further entrapped in a water-in-oil-in-water emulsion system for a sustained release profile. The CMC/Fe3O4@SiO2/QC nanoparticles were characterized using dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), a field emission scanning electron microscope (FE-SEM), and a vibrating sample magnetometer (VSM) to obtain insights into their size, stability, functional groups/chemical bonds, crystalline structure, morphology, and magnetic properties, respectively. The entrapment and loading efficiency were slightly improved after the incorporation of Fe3O4@SiO2 NPs within the hydrogel network. The dialysis method was applied for drug release studies. It was found that the amount of QC released increased with the decrease in pH from 7.4 to 5.4, while the sustained-release pattern was preserved. The A549 cell line was chosen to assess the anticancer activity of the CMC/Fe3O4@SiO2/QC nanoemulsion and its components for lung cancer treatment via an MTT assay. The L929 cell line was used in the MTT assay to determine the possible side effects of the nanoemulsion. Moreover, a flow cytometry test was performed to measure the level of apoptosis and necrosis. Based on the obtained results, CMC/Fe3O4@SiO2 can be regarded as a novel promising system for cancer therap

Improving quercetin anticancer activity through a novel polyvinylpyrrolidone/polyvinyl alcohol/TiO2 nanocomposite

A hydrogel nanocomposite comprising polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and titanium oxide (TiO2) was prepared and encapsulated in a double emulsion as a pH-triggered delivery vehicle for quercetin (QC), an antitumor drug. Dynamic light scattering (DLS) was used to estimate the size and confirm the stability of QC-loaded nanoparticles. The interactions between the nanocomposite components, its crystalline structure and the morphology of the nanoparticles were characterized through Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. Drug loading and encapsulation efficiency significantly improved after incorporation of TiO2, which corroborates the beneficial effect of this component. In vitro release experiments indicated the pH-responsivity of the nanocarrier, with higher amount of QC released in an acidic medium than at neutral pH. Due to the presence of a double emulsion, the release pattern was sustained and gradual in both environments. Cellular experiments including MTT assay and flow cytometry were conducted using U87 cell line to compare the anticancer activity of free QC and QCloaded nanoparticles. MTT assay was also performed on a noncancerous cell line (L929) to assess potential side effects of the drug release system. The results obtained herein confirm the suitability of the developed nanocarrier as an efficient drug delivery vehicle for tumor therapy.Comunidad de Madri

The synthesis of methotrexate-loaded F127 microemulsions and their in vivo toxicity in a rat model

Methotrexate (MTX) has been often formulated as nano and micro-emulsions, nominally to address its poor solubility and off-target effects. Nanoformulated MTX is universally reported to be a more efficacious anti-cancer agent than direct-dissolved drug; however, these investigations generally fail to screen for in vivo toxicity. This study aims to remedy this oversight. MTX was formulated as a standard Pluronic oil-in-water microemulsion with good drug encapsulation efficiency (73.0% ± 8.4). Preliminary in vitro free radical scavenging studies found that formulation reduces drug oxidation four-fold. The toxic effects of formulated and unformulated MTX were investigated in a Wistar rat model. Rats received 0.05 mg/kg MTX as either the microemulsion or directly dissolved in phosphate-buffered saline. A drug-free microemulsion, PBS solution, and saline solution were used as controls. After 28 days, serum levels of enzymes indicative of kidney and liver damage were quantified. Significantly higher serum liver, and serum kidney enzymes were observed in the rats that received the directly dissolved MTX drug (P \u3c 0.05) compared to those who received the encapsulated form. Following sacrifice, the levels of catalase and superoxide dismutase (SOD) were significantly lower and the level of malondialdehyde higher, in rats who received either form of MTX relative to untreated controls. However, the SOD levels were lower in those who received the microemulsion than those who received free MTX. Histology supported the observation that the microemulsion formulation caused no gross structural toxicity to the liver, unlike the free drug. Although toxicity was reduced compared to the free drug, the microemulsion still caused damage to the kidneys. This organ-specific toxicity is consistent with the mode of clearance of the drug. This data demonstrates that the toxicity of formulated drugs must be considered when discussing the relative merits of formulations: encapsulation almost always improves efficacy but may not improve safety

The synthesis and characterization of a magnetite nanoparticle with potent antibacterial activity and low mammalian toxicity

Magnetite has shown some promise as a biomedical material and antibacterial agent; however the benefits are normally only realized when it is used in combination with other metals or drugs. Unfunctionalized magnetite may be a biocompatible alternative. This report discusses the synthesis and potent antibacterial activity, with low associated mammalian organ toxicity, of nanomagnetite particles. Magnetite (Fe3O4) nanoparticles were electrochemically prepared in a green surfactant-free, closed water loop system. These materials, characterized by X-ray diffraction, FTIR, and vibrational magnetometry, also appear contaminated with Fe-O-O-H functionalities. This physical characterization is accompanied by a computational investigation of truncated clusters showing that a magnetite-derived cluster of 7 iron atoms is a sufficient model to generate the vibrational frequencies experimentally observed in magnetite using DFT calculations. The nanoparticles, evaluated for antibiotic activity, were shown to have minimum inhibitory concentrations of 2.8 and 2.0 μg/mL against E. coli and S. aureus respectively. This is both a 100-fold lower concentration than the human cytotoxic dose determined by an MTT assay and is also comparable to the effective dose of traditional antibiotics. A dose-dependent decrease in catalase activity and an increase in the levels of lipid peroxidation suggests that these nanoparticles act through damaging the anti-oxidant systems in cells. However, renal and hepatic damage was only observed at daily doses (2 weeks) of 100 μg/mL and higher. This significant therapeutic window suggests that these materials might prove useful as potential complementary therapeutics in the future

Computational, experimental details, and biological raw data accompanying the publication: “The synthesis and characterization of a nanomagnetite with potent antibacterial activity and low mammalian toxicity”

This data file includes experimental details on how to make uncoated iron oxide nanoparticles using a green electrochemical method. It provides the raw data on the antibacterial activity of one of these formulations, and the full computational data and methodology used to generate that data, of several different magnetite clusters of specific spin multiplicities for 4, 5, 7 and 9 iron atom magnetite clusters. This data will assist other researchers wishing to replicate or expand on these results for the investigation and use of nanomagnetite for antibacterial applications