Studies on rheological,thermal, and morphological properties of methylcellulose gel in aqueous medium

The rheological, morphological, and thermal behavior of aqueous methylcellulose (MC) gels was investigated by optical microscope, dynamic mechanical analyzer (DMA), and differential scanning calorimeter. The double crossover between the storage modulus and loss modulus during the frequency scan in DMA suggests the transition from gel to sol state. These gel networks are comprised of bead‐rod structures, which is visible under the optical microscope. Furthermore, the degelation mechanism of gels comprises of the thermodynamic viable bead burst phenomenon. The reheated samples of MC under dynamic compression show partial irreversibility of the MC aqueous system, indicating the possible presence of weakly coupled random coils and helix. The phenomenon of turbidity of MC aqueous gels is discussed with the help of a large bead model, in which the small‐sized beads present in aqueous solution collide with each other to form large beads. POLYM. ENG. SCI., 59:2024–2031, 2019. © 2019 Society of Plastics Engineers     

Oxidative stress induces apoptosis in embryonic cortical neurons

Glutamate-induced glutathione depletion in immature embryonic cortical neurons has been shown to lead to oxidative stress and cell death. We have used this in vitro model to investigate the mechanism(s) by which free radicals induce neuronal degeneration. We find that glutathione depletion leads to hyper-condensation and fragmentation of chromatin into spherical or irregular shapes, a morphologic signature of apoptosis. These morphologic changes are accompanied by laddering of DNA into multiple oligonucleosomal fragments and can be prevented by the antioxidants idebenone and butylated hydroxyanisole. Cell death induced by glutathione depletion can also be prevented by inhibitors of macromolecular synthesis. Taken together, these observations suggest that oxidative stress can induce apoptosis in neurons.     

Solar cells using quantum funnels

Colloidal quantum dots offer broad tuning of semiconductor bandstructure via the quantum size effect. Devices involving a sequence of layers comprised of quantum dots selected to have different diameters, and therefore bandgaps, offer the possibility of funneling energy toward an acceptor. Here we report a quantum funnel that efficiently conveys photoelectrons from their point of generation toward an intended electron acceptor. Using this concept we build a solar cell that benefits from enhanced fill factor as a result of this quantum funnel. This concept addresses limitations on transport in soft condensed matter systems and leverages their advantages in large-area optoelectronic devices and systems.     

Isosorbide Fatty Acid Diesters Have Synergistic Anti-Inflammatory Effects in Cytokine-Induced Tissue Culture Models of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic disease in which epidermal barrier disruption triggers Th2-mediated eruption of eczematous lesions. Topical emollients are a cornerstone of chronic management. This study evaluated efficacy of two plant-derived oil derivatives, isosorbide di-(linoleate/oleate) (IDL) and isosorbide dicaprylate (IDC), using AD-like tissue culture models. Treatment of reconstituted human epidermis with cytokine cocktail (IL-4 + IL-13 + TNF-α + IL-31) compromised the epidermal barrier, but this was prevented by co-treatment with IDL and IDC. Cytokine stimulation also dysregulated expression of keratinocyte (KC) differentiation genes whereas treatment with IDC or IDL + IDC up-regulated genes associated with early (but not late) KC differentiation. Although neither IDL nor IDC inhibited Th2 cytokine responses, both compounds repressed TNF-α-induced genes and IDL + IDC led to synergistic down-regulation of inflammatory (IL1B, ITGA5) and neurogenic pruritus (TRPA1) mediators. Treatment of cytokine-stimulated skin explants with IDC decreased lactate dehydrogenase (LDH) secretion by more than 50% (more than observed with cyclosporine) and in vitro LDH activity was inhibited by IDL and IDC. These results demonstrate anti-inflammatory mechanisms of isosorbide fatty acid diesters in AD-like skin models. Our findings highlight the multifunctional potential of plant oil derivatives as topical ingredients and support studies of IDL and IDC as therapeutic candidates.     

Semiconductor metal oxide compounds based gas sensors: A literature review

This paper gives a statistical view about important contributions and advances on semiconductor metal oxide (SMO) compounds based gas sensors developed to detect the air pollutants such as liquefied petroleum gas (LPG), H₂S, NH₃, CO₂, acetone, ethanol, other volatile compounds and hazardous gases. Moreover, it is revealed that the alloy/composite made up of SMO gas sensors show better gas response than their counterpart single component gas sensors, i.e., they are found to enhance the 4S characteristics namely speed, sensitivity, selectivity and stability. Improvement of such types of sensors used for detection of various air pollutants, which are reported in last two decades, is highlighted herein.     

Thermogelation of methylcellulose from solution in N,N‐dimethylformamide and characterization of the transparent gels

A transparent gel was prepared through the cooling of a methylcellulose (MC) solution in N,N‐dimethylformamide (DMF) at 80°C to a lower temperature. The temperature at which gelation occurred was dependent on the concentration of the solution. The gel temperature increased with an increase in the concentration of MC. The gelation of MC in DMF was studied by means of optical microscopy (OM), differential scanning calorimetry, and dynamic mechanical analysis (DMA). The OM studies revealed the presence of loosely bound beads of MC with DMF at a lower concentration. These beads became interconnected to rods, and subsequently, a continuous, thick gel was formed as the concentration increased. From DMA studies, it was observed that the loss modulus of the gel crossed over the storage modulus at two different frequencies. This indicated the presence of two types of network structures generated from the weak and strong associations of MC with the organic solvent DMF. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dietary Methionine Deficiency Enhances Genetic Instability in Murine Immune Cells

Both cell and animal studies have shown that complete or partial deficiency of methionine inhibits tumor growth. Consequently, the potential implementation of this nutritional intervention has recently been of great interest for the treatment of cancer patients. Unfortunately, diet alteration can also affect healthy immune cells such as monocytes/macrophages and their precursor cells in bone marrow. As around half of cancer patients are treated with radiotherapy, the potential deleterious effect of dietary methionine deficiency on immune cells prior to and/or following irradiation needs to be evaluated. Therefore, we examined whether modulation of methionine content alters genetic stability in the murine RAW 264.7 monocyte/macrophage cell line in vitro by chromosomal analysis after 1-month culture in a methionine-deficient or supplemented medium. We also analyzed chromosomal aberrations in the bone marrow cells of CBA/J mice fed with methionine-deficient or supplemented diet for 2 months. While all RAW 264.7 cells revealed a complex translocation involving three chromosomes, three different clones based on the banding pattern of chromosome 9 were identified. Methionine deficiency altered the ratio of the three clones and increased chromosomal aberrations and DNA damage in RAW 264.7. Methionine deficiency also increased radiation-induced chromosomal aberration and DNA damage in RAW 264.7 cells. Furthermore, mice maintained on a methionine-deficient diet showed more chromosomal aberrations in bone marrow cells than those given methionine-adequate or supplemented diets. These findings suggest that caution is warranted for clinical implementation of methionine-deficient diet concurrent with conventional cancer therapy.