Development And Characterization Of Moisture-Blown Natural Rubber Foam Prepared By Microwave Foaming Technique

Investigation has been done on the feasibility of utilizing microwave radiation in foaming natural rubber. It was found that microwave foaming was able to foam natural rubber and the microwave processing is having advantages over both single and two-stage foaming process. Natural rubber is naturally non-polar and unsusceptible to microwave heating, but its behavior under the influence of microwave can be modified by incorporation of various additives. Foam with relative density as low as 0.14 can be produced with 8 pphr of azodicarbonamide (ADC) added, however signs of degradation can be observed when higher concentration of ADC was utilized. More interestingly, the moisture content in the rubber compound itself was able to act as a potential physical blowing agent with the aids of microwave radiation. Foam with the lowest relative density from this research, i.e. 0.10, was able to be produced by exploiting 1.25% moisture content in rubber compound. The successful foaming with moisture exceeded those foams formed with the addition of 10 pphr of azodicarbonamide. This would revolutionize the foam industry since water is a low cost, abundant and non-toxic material. The addition of fillers, silica and carbon black, will increase the susceptibility of rubber compound towards microwave heating, but in different manners. Silica will increase the polarity of rubber compound while carbon black increases the electrical conductivity of the compound. It was found that the addition of more than 10 pphr of both fillers ended up with unsuccessful production of natural rubber foam. For silica-added compound, the high viscosity of polymer melt available during foaming restricted the expansion of rubber matrix. In the case of carbon black added compound, the rapid rise in temperature under microwave radiation would burn and degrade the compound before the foam structure can be formed

Physiological and visible injury responses in different growth stages of winter wheat to ozone stress and the protection of spermidine

AbstractThe open top chamber (OTC) method was used in a farmland to study the influence of different levels of O3 concentrations (40 ppb, 80 ppb and 120 ppb) on the enzymatic activity and metabolite contents of the antioxidation system of the winter wheat leaves during the jointing, heading and milk stage. The protective effect of exogenous spermidine (Spd) against the antioxidation of winter wheat under the O3 stress was investigated. With the increasing O3 concentrations and fumigation time, the injuries of the winter wheat leaves were observed to be more serious. For instance, when the O3 concentration reached 120 ppb, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and nitrate reductase (NR) in the jointing stage decreased by 50.3%, 64.9%, 75.5% and 92.9%, respectively; peroxidase (POD) and glutathione reductase (GR) increased by 45.1% and 80.5%, respectively; the contents of malondialdehyde (MDA), ascorbic acid (AsA) and reduced glutathione (GSH) increased by 314.3%, 8.4% and 31.7%, respectively; and the soluble protein (SP) content decreased by 47.5%. The O3 stress also had significant impact on the contents of proline (Pro), NO3––N and NH4+–N of the winter wheat leaves. During the heading stage, when the O3 concentration was 40 ppb and 80 ppb, the content of Pro was 163.9% and 173.2% higher than that in the control group, respectively. But under 120 ppb, it was decreased by 42.4%. Exogenous application of Spd increased the activities of SOD, POD, CAT, APX and GR, as well as the contents of GSH and SP, but decreased the contents of MDA and AsA. This indicates that Spd is an effective antioxidant to relieve the O3 stress on winter wheat leaves, thereby might be applicable to protect winter wheat from the harm of O3

Identifying TNF and IL6 as potential hub genes and targeted drugs associated with scleritis: A bio-informative report

BackgroundScleritis is a serious inflammatory eye disease that can lead to blindness. The etiology and pathogenesis of scleritis remain unclear, and increasing evidence indicates that some specific genes and proteins are involved. This study aimed to identify pivotal genes and drug targets for scleritis, thus providing new directions for the treatment of this disease.MethodsWe screened candidate genes and proteins associated with scleritis by text-mining the PubMed database using Python, and assessed their functions by using the DAVID database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to identify the functional enrichment of these genes and proteins. Then, the hub genes were identified with CytoHubba and assessed by protein-protein interaction (PPI) network analysis. And the serum from patients with active scleritis and healthy subjects were used for the validation of hub genes. Finally, the DGIdb database was used to predict targeted drugs for the hub genes for treating scleritis.ResultsA total of 56 genes and proteins were found to be linked to scleritis, and 65 significantly altered pathways were identified in the KEGG analysis (FDR < 0.05). Most of the top five pathways involved the categories “Rheumatoid arthritis,” “Inflammatory bowel disease”, “Type I diabetes mellitus,” and “Graft-versus-host disease”. TNF and IL6 were considered to be the top 2 hub genes through CytoHubba. Based on our serum samples, hub genes are expressed at high levels in active scleritis. Five scleritis-targeting drugs were found among 88 identified drugs.ConclusionsThis study provides key genes and drug targets related to scleritis through bioinformatics analysis. TNF and IL6 are considered key mediators and possible drug targets of scleritis. Five drug candidates may play an important role in the diagnosis and treatment of scleritis in the future, which is worthy of the further experimental and clinical study

Toxicity and bioaccumulation of heavy metals in spinach (spinacia oleracea) grown in a controlled environment

The impact of heavy metal toxicity on the shoot and root lengths, total protein, fiber characteristics, moisture content and nutrient composition of spinach (Spinacia oleracea) was evaluated. Plants were grown in pots containing soil and treated with different concentrations (mg/kg) of lead (Pb; 300, 400 and 500), cadmium (Cd; 0.5, 1 and 1.5) and zinc (Zn; 250, 500, and 700) as well as mixtures of Cd and Pb (0.5/300, 1/400, 1.5/500), Cd and Zn (0.5/250, 1/500, 1.5/700), and Pb and Zn (300/250, 400/500, 500/700). Soil contaminated by long-term irrigation with wastewater containing heavy metals was simulated. An increase in concentrations of heavy metals both individually and as mixtures significantly (p < 0.05) reduced the growth parameters and nutrient contents of S. oleracea. The uptake patterns of heavy metals in mixtures showed antagonistic impacts on each other. The toxicities of the mixtures Cd and Pb, Cd and Zn as well as Pb and Zn were higher than those observed in separate heavy metal applications but less than their additive sums. The toxicity caused by individual heavy metals was the highest for Cd followed by Pb and Zn. The highest toxicity was observed in plants grown in soil contaminated by Cd and Pb

Učinak bakra na toksičnost i genotoksičnost kadmija u vodenoj leći (Lemna minor L.)

We investigated interactions between copper (in the concentrations of 2.5 μmol L-1 and 5 μmol L-1) and cadmium (5 μmol L-1) in common duckweed (Lemna minor L.) by exposing it to either metal or to their combinations for four or seven days. Their uptake increased with time, but it was lower in plants treated with combinations of metals than in plants treated with either metal given alone. In separate treatments, either metal increased malondialdehyde (MDA) level and catalase and peroxidase activity. Both induced DNA damage, but copper did it only after 7 days of treatment. On day 4, the combination of cadmium and 5 μmol L-1 copper additionally increased MDA as well as catalase and peroxidase activity. In contrast, on day 7, MDA dropped in plants treated with combinations of metals, and especially with 2.5 μmol L-1 copper plus cadmium. In these plants, catalase activity was higher than in copper treated plants. Peroxidase activity increased after treatment with cadmium and 2.5 μmol L-1 copper but decreased in plants treated with cadmium and 5 μmol L-1 copper. Compared to copper alone, combinations of metals enhanced DNA damage after 4 days of treatment but it dropped on day 7. In conclusion, either metal given alone was toxic/genotoxic and caused oxidative stress. On day 4 of combined treatment, the higher copper concentration was more toxic than either metal alone. In contrast, on day 7 of combined treatment, the lower copper concentration showed lower oxidative and DNA damage. These complex interactions can not be explained by simple antagonism and/or synergism. Further studies should go in that direction.U svrhu istraživanja interakcija između bakra kao esencijalnog elementa te kadmija kao neesencijalnog i toksičnog metala, vodenu leću Lemna minor L. uzgajali smo na podlogama s kadmijem (5 μmol L-1) odnosno s bakrom (2,5 μmol L-1 i 5 μmol L-1) te s njihovim kombinacijama. Unos metala u biljke povećavao se s trajanjem pokusa, a kod kombinacije metala u biljkama je izmjerena niža količina kadmija nego u onima uzgajanima samo na kadmiju. U biljkama tretiranim pojedinačnim metalom došlo je do povećanja sadržaja malondialdehida (MDA) te aktivnosti katalaze i peroksidaze u odnosu na kontrolne biljke. Također, primijećeno je oštećenje DNA iako kod bakra tek sedmog dana tretmana. Količina MDA i aktivnost obaju enzima dodatno se povećala na tretmanu kombinacijom kadmija i bakra (5 μmol L-1) nakon četvrtog dana pokusa, dok se količina MDA smanjila nakon sedmog dana kod kombinacije kadmija i 2,5 μmol L-1 bakra. U tim biljkama primijećena je i veća aktivnost katalaze, dok je aktivnost peroksidaze porasla na tretmanu kadmijem i 2,5 μmol L-1 bakrom, ali se smanjila na tretmanu kadmijem i 5 μmol L-1 bakrom. Oštećenje DNA koje je bilo veće kod kombinacije metala nakon četvrtog dana, osobito u usporedbi sa samim bakrom, smanjilo se nakon sedmog dana pokusa. Iz ovih rezultata može se zaključiti da su oba metala u istraživanim koncentracijama toksična i genotoksična za vodenu leću i da uzrokuju oksidacijski stres. Kadmij u kombinaciji s bakrom više koncentracije bio je toksičniji od pojedinačnih metala nakon četvrtog dana pokusa, dok su u biljaka tretiranih kombinacijom kadmija i bakra niže koncentracije toksični učinci bili manji. Budući da su primijećene interakcije vrlo kompleksne i ne uključuju samo antagonizam odnosno sinergizam potrebna su daljnja istraživanja

Dynamic Modeling and Robust Adaptive Sliding Mode Controller for Marine Cable-Driven Parallel Derusting Robot

Ship derusting has the characteristics of a complex operation environment, high labor intensity and low efficiency. In order to better cope with this situation, a new type of cable-driven parallel derusting robot (CDPDR) is proposed in this article. To improve the positioning accuracy and anti-interference capacity of the motion platform where the end effector is mounted, the system&rsquo;s dynamic model, considering wave excitation, is established. Further, the controllable workspace and cable tension optimization algorithm are studied. In addition, a fast non-singular terminal sliding-mode controller is designed. Meanwhile, the adaptive technique is used to estimate the disturbance upper bound. Then, the Lyapunov theory is applied to prove the stability of the system. Finally, the performance of the controller is verified by high-fidelity simulations in two different scenarios. The results show that the proposed controller can converge in finite time and maintain small error under multiple external disturbances. The relevant research in this article can provide theoretical guidance for the application of CDPDRs on ships

Kinetics-based Particle Size Engineering of Polymeric Gene Delivery Vehicles

Intracellular gene delivery has significant values in treating genetic and acquired diseases in vivo and in engineering cells ex vivo or in vitro for therapeutic applications. Compared to viral approaches, non-viral delivery using gene-loaded vehicles formed by polymeric carriers has advantages of lower immunogenicity, easier manufacturing, and chemical versatility to render desired vehicle properties. For such vehicles, size is a central property that determines their payload capacity of the therapeutic cargo and the polymer carrier, and more importantly, their interactions with biological systems such as blood circulation, the immune system, a local tissue, and a single cell. Controlling the size of the vehicles optimizes their performances with the potential to improve efficacy and biocompatibility and is necessary from a quality control perspective for clinical translation. This thesis sought to achieve size control of polymeric gene delivery vehicles in a precise and scalable manner and examine size-controlled vehicles in applications in vitro and in vivo. Chapter one outlines the major aims of this thesis. Chapter two provides the background on polymeric gene delivery vehicles, prior arts on vehicle size control methods, and prior reports on the effects of vehicle size on the interactions with biological systems. Chapter three describes the establishment of a single-nanoparticle assessment method, i.e., multi-laser cylindrical illumination confocal microscopy, that allows characterization of the payload capacity along with vehicle size. Chapter four first reports the findings in the investigation of the assembly kinetics of polymeric nucleic acid nanoparticles with a highlight on the essentialness of controlling the mixing kinetics in the formulation process. It then reports discovery of 80 nm as the optimal size for an in vivo application of DNA delivery to the lungs. Chapter five developed a supramolecular assembly strategy to extend size control to the full nano-to-micron size range (30 to 1000 nm) based on the mechanistic insights on vehicle assembly kinetics. It also reports the discovery of 400 nm as the optimal size for an in vitro transfection application while giving brief discussions on the mechanisms. Chapter six applied a similar supramolecular assembly strategy on a carrier system better suited for in vivo gene delivery, and surprisingly realized an optimal size near 400 nm again for mRNA delivery to myeloid cells. Chapter seven describes how the production of size-controlled polymeric gene delivery vehicles can be scale up to meet need for clinical translation