Effect of pro-oxidant concentration on characteristics of packaging films of cobalt stearate filled polypropylene

In this work, polypropylene (PP) filled with different proportions of CoSt were prepared in a twin-screw extruder by compounding technique. Eight films of these compounds were prepared using compression moulding. The modified PP films were characterized for chemical, physical, thermal, and morphological properties (before and after biodegradation). The biodegradation of the CoSt filled PP films was studied under controlled composting conditions, and the degradation intermediates were evaluated for their ecotoxicological impact. The CoSt present in the PP film was confirmed by Fourier transform infrared spectroscopy. As the addition of CoSt was progressively increased, the tensile strength and thermal stability decreased as shown by UTM and thermogravimetric analysis. The compounding of CoSt in PP reduced its crystallinity as revealed by the differential scanning calorimetry and X-ray diffraction analysis, and this led to enhanced degradation of PP. After biodegradation, SEM results of modified PP films showed rougher morphology than before biodegradation. The maximum biodegradation (19.78%) was shown by the film having 2 phr CoSt. The ecotoxicity tests of the degraded material, namely, microbial test, plant growth test, and earthworm acute-toxicity test demonstrated that the biodegradation intermediates were nontoxic. Hence, CoSt filled PP has high industrial potential to make biodegradable flexible packaging.

Gradient-degraded material-induced trigger to improve crashworthiness of composite tubes in a controlled manner

A type of gradient-degraded material-induced trigger has a greater potential to induce a progressive crushing mode in a controlled manner to reduce the initial crushing load and increase the specific energy absorption. Thus, different material degradation strategy-based triggers are designed to improve the crashworthiness of composite tubes. To understand the triggering mechanisms, effects of height of trigger and level of degradation are studied using single material degradation strategies. In turn, gradient material degradation strategies are novelly presented to explore different crushing behaviors of tube. Further, an improved gradient material degradation gathering all features of single material degradation and gradient material degradation is proposed. The virtual quasi-static crushing tests are conducted where the model considers intra-ply and inter-ply failure initiation and damage evolution. The crushing behaviors of all triggered tubes are compared. From the predicted results, it is found that both the height of trigger and level of degradation have significant effects on the crushing behavior. The multi-phased or progressive initial crushing process is presented by using gradient material degradation. By comparison, the tube using the improved gradient material degradation presents 8.26% lower peak load, 8.75% higher specific energy absorption, and 25% higher crushing load stability than the original tube.

Autophagy Activator Drugs: A New Opportunity in Neuroprotection from Misfolded Protein Toxicity

The aim of this review is to critically analyze promises and limitations of pharmacological inducers of autophagy against protein misfolding-associated neurodegeneration. Effective therapies against neurodegenerative disorders can be developed by regulating the “self-defense” equipment of neurons, such as autophagy. Through the degradation and recycling of the intracellular content, autophagy promotes neuron survival in conditions of trophic factor deprivation, oxidative stress, mitochondrial and lysosomal damage, or accumulation of misfolded proteins. Autophagy involves the activation of self-digestive pathways, which is different for dynamics (macro, micro and chaperone-mediated autophagy), or degraded material (mitophagy, lysophagy, aggrephagy). All neurodegenerative disorders share common pathogenic mechanisms, including the impairment of autophagic flux, which causes the inability to remove the neurotoxic oligomers of misfolded proteins. Pharmacological activation of autophagy is typically achieved by blocking the kinase activity of mammalian target of rapamycin (mTOR) enzymatic complex 1 (mTORC1), removing its autophagy suppressor activity observed under physiological conditions; acting in this way, rapamycin provided the first proof of principle that pharmacological autophagy enhancement can induce neuroprotection through the facilitation of oligomers’ clearance. The demand for effective disease-modifying strategies against neurodegenerative disorders is currently stimulating the development of a wide number of novel molecules, as well as the re-evaluation of old drugs for their pro-autophagic potential.

Investigation of Defect Effects on Adhesively Bonded Joint Strength Using Cohesive Zone Modeling

In this paper, effects of the defect in an adhesively bonded joint have been investigated using cohesive zone modeling. Consequently, a 3D finite element model of a single lap-joint is constructed and validated with experiments. Strength prediction of current model is found desirable. Accordingly, different sizes of square shape defects are imported to model in the form of changing (raised or degraded) material properties (heterogeneity) and locally delaminated areas (as inclusion/void), respectively. Joint strength is investigated and a stress analysis is carried out for adhesive layer and adherends. Obtained Results show that, defect has significant impact on the results. It is found that at constant size of defect, local delamination has more impact on bonded joint strength than the heterogeneity. Furthermore, stress analyses demonstrate that the stress field does not change in adherends by taking defects into account. However, stress values decrease with degraded material properties and joint’s strength. Through evaluation of peel and transverse shear stresses in adhesive layer it is found that there is a change of stress distribution for both types of defects. Whereas, there is a considerable stress concentration in the delaminated adhesive layer.

Experimental Assessment of the Sealing Potential of Hydrated Solgel for the Remediation of Leaky Reservoirs

The full-scale deployment of underground storage of CO2 in permeable sedimentary reservoirs depends strongly on the sealing capacity of the caprocks and wellbore cement that may be degraded leading to hydraulic discontinuities. Remediation technologies consisting in rebuilding the sealing capacity of the degraded material, or adding a new sealing layer, is a critical issue as part of the risk mitigation procedure required for underground CO2 storage. Actually, engineered Portland cement injection is the foremost available industrial technique; however, alternative products offering, for instance, better injection properties, are currently investigated with variable success so far. In this study, a new technique aimed at using a low viscosity hydrated solgel as sealant product in case of leakage is presented. Its low cost, high injectivity capacity and low density of the hydrated product (hydrogel) makes this technique attractive. The solgel synthesis was optimized for (1) reducing energetic and material costs; (2) improving the chemical and mechanical properties of the emplaced product and (3) controlling the duration of the aging process in order to form a solid hydrogel after a few days. Permeability tests that consisted of injecting the synthesized solgel in different porous media confirmed the sealant capacity of the emplaced hydrogel to significantly reduce rock permeability.

Analysis of Product and Temperature of Biogas Combustion in Various Air Biogas Equivalence Ratio and Methane Content

Biogas resulted from anaerobic digestion of organic compounds have various methane content depend on the type of the degraded material. The methane content of biogas is range between 40–80% that influence the heating value and combustion characteristic of that biogas. The higher methane content can be obtained through upgrading biogas by removing CO2 and other trace components like H2S, NH3, and water vapor. This research was a simulation of product composition and temperature of biogas combustion in various methane content and air biogas equivalence ratio. Biogas combustion was done in combustion chamber at constant pressure of 1 atm. Biogas and air enter into combustion chamber at temperature approximately of 30 °C as the common ambient temperature in Indonesia. The input air was designed higher than stoichiometric need in order to reach complete combustion. Combustion reaction between methane and O2 then carried out in the combustion chamber to produce CO2 and H2O. The product gases consisting of CO2, H2O, N2, and excess O2, bring heat from combustion reaction and exit from combustion chamber at the higher temperature. The analysis was done for methane content range between 20 and 100% with air biogas equivalence ratio from 1 until 3. The simulation result showed that for V m3 biogas, the combustion gases could reach 0.12271 until 1.26798V gmol with temperature above 700 °C until above 1900 °C. More than 50% component in the combustion gases is N2 as inert material from input air to combustion chamber.

PERUBAHAN PARAMETER BIOGEOFISIK DAN LINGKUNGAN TPA SAMPAH LEUWIGAJAH PASCA BENCANA LONGSOR

This study is conduct to evaluate the changes of biogeophysical aspects of Leuwigajah Dumping Area (TPA) after the slidding event of municipal solid wastes in 2005. It is necessary to reuse the TPA in the future through rehabilitation and revitalitation.The study is important due to the detail engineering design (DED) of new TPA which is still in an on going process, whereas need some consideration from technical and non-technical aspects. The result of geological survey showed that there is no signifi cant changes in geological condition, whether the changes were found in groundwater and surface water quality, before and after the slidding event. At the other side, the result of existing solid waste material showed that a high heavy metals content was found in the bulk material. It isalso found that the quality of degraded material yet is closed to compost, with a C/N ratio between 12,04 to 15,74. This compost-soil is recommended for daily cover soil at the TPA. So, before operating a new TPA, landfi ll mining must be done as initial activity.To reduce or minimize environmental impact the new TPA has to apply sanitary landfi ll method.Key words : biogeophysical, post slidding , Leuwigajah dumping area

Altering the Biodegradation of Mesoporous Silica Nanoparticles by Means of Experimental Parameters and Surface Functionalization

Mesoporous silica nanoparticles (MSNPs) are gaining a large interest in the field of medical and biomedical applications due to their biodegradability and high loading capacity as a carrier. In this work, a simple synthesis and functionalization procedure is reported, which allows tuning the nanoparticle properties, functionalization, and biodegradability. Variations in the synthesis procedure are introduced, including temperature, concentration of catalyst, and surface functionalization. These samples are characterized and afterwards degraded in phosphate buffered saline (PBS) to determine their degradation kinetics. The amount of degraded material is colorimetrically determined, using an optimized protocol based on molybdenum blue chemistry. It is shown that the degradability of the nanoparticles increased with decreasing synthesis temperatures, lower amounts of catalyst, and higher concentrations of nanoparticles. Surface functionalization alters the degradation kinetics as well, rendering amino-functionalized nanoparticles the fastest degradation behavior, followed by carboxylated and nonfunctionalized nanoparticles. From these results, it can be concluded that the degradation rate of MSNPs can be varied from a few hours to several days by small changes in the synthesis procedure. Moreover, the degradation behavior is strongly dependent on the nanoparticle growth rate.

Effect of the Prodegradant-Additive Plastics Incorporated on the Polyethylene Recycling

The effect of degraded plastic with prodegradants on the polyethylene properties was studied. First, the mixture of low-density polyethylene (LDPE) with 5 wt.% prodegradant (oxo-degradable) additive was prepared by melt processing using a mixer chamber. Then, the degradation of the mixtures was evaluated by exposing the oxo-degradable LDPE in a Xenon arc chamber for 300 hours. The degraded material was characterized by infrared spectroscopy (FTIR) assessing the carbonyl index and the hydroperoxide band. Then, different percentages of degraded material (1, 5, 10, 20, and 50 wt.%) were incorporated into the neat LDPE. Mechanical and rheological tests were carried out to evaluate the recycling process of these blends. Also, the feasibility of the blends reprocessing was determined by analysing the melt flow index for each heating process and shear stress applied. It was evidenced that the increment of the content of the degraded material in the neat LDPE decreased the mechanical strength and the processability of blends due to the imminent thermal degradation. All the test results showed that the incorporation of degraded material causes a considerable reduction in the matrix properties during the reprocessing. Nevertheless, at low concentrations, the properties of the oxo-degradable LDPE–LDPE blends were found to be similar to the neat LDPE.