Lifestyle and Diet
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Plastics are synthetic organic polymers. They are composed of hydrocarbons that are prepared from fossil fuel (petroleum) or other products under the action of heat (214). Plastics liberate their toxic monomers, bisphenol-A (BPA) and di-(2-ethylhexyl)-phthalate (DEHP), during decomposition into the environment or during contact with foods or human tissues. BPA and DEHP are well-known strong endocrine disruptors which can interfere with human hormone systems, and consequently, can engender a number of diseases such as infertility, sex deformation, retardation of brain development in children, and cancers of prostate, breast, thyroid (213). At present, BPA has been one of the first plastic materials to be recognized for its potential harm by the US Food and Drug Administration (FDA) (213). In response to such concerns, BPA also recently has been banned in the United States as well as in Canada and the European Union from use in infant bottles and spill-proof cups for toddlers. Do not heat or boil food in plastic containers by microwave. Replace plastic items with porcelain or glass objects. Detectable levels of bisphenol A have been found in the urine of 95% of the adult population of the United States (213).
Polymer/Surfactant Interaction
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
contact between hydrocarbon chains and water is offset by the energy gained in the electrical repulsion of ionic head groups brought into proximity in the micelle periphery. The net result is that micellization represents a very delicate balance of forces. For example, adding salt, which reduces the micellar head group repulsive forces, or lengthening the “R” group of the surfactant, which increases the energy loss on eliminating the hydrocarbon chain/water interface, can sharply reduce the c.m.c. In any event, there will always be a high level of counterion binding by ionic surfactant micelles because of electrostatic attraction.Nonionic surfactants are a special case. Because of the absence of electrical repulsive forces at the micellar periphery, aggregation takes place at a much lower concentration. For the same R group the c.m.c. of a nonionic surfactant can be two orders of magnitude lower than that of an ionic surfactant. Also, micellar shapes other than spherical, e.g., ellipsoids, are frequently encountered. All of the above factors, as will be seen, have a bearing on the subject of polymer/surfactant interaction.Polymers
Extraction and Chemistry of Rubber Allergens
Robert N. Phalen, Howard I. Maibach in Protective Gloves for Occupational Use, 2023
Both synthetic and natural latexes, also known as elastomers, are colloidal suspensions of polymeric materials in aqueous systems that require vulcanization to produce rubber gloves. Vulcanization is the process where the rubber molecules are polymerized through cross-linking by sulfur to increase tear and tensile strength, stretch ability, and other desired physical properties. CR vulcanization uses metal oxides such as MgO and ZnO. Sulfur vulcanization of latex is a necessary step in the production of NRL, IIR, NBR, EPDM, and SBR gloves. For sulfur crosslinking to occur, the rubber elastomers must have C=C bonds which require modification of EDPM and IIR to be amenable to sulfur vulcanization. The use of sulfur alone produces very slow vulcanization that requires high temperatures resulting in a product that is prone to oxidative degradation and has poor physical properties. The use of chemical accelerators allows for lower vulcanization temperatures and increases vulcanization efficiency. The type of accelerator(s) used is dependent on the type of rubber and desired product properties. Many of these accelerators are known to cause contact allergies.
Functional detection of the original generation of hippocampal cells planted on to the micro-fluidic chip with artificial neuronal network using the patch clamp recording technique: a preliminary study
Published in International Journal of Neuroscience, 2019
Xianmin Kong, Shanshan Tian, Tao Chen, Yinghui Huang
Currently, the materials used in micro-fluidic chip include silicon, glass, organic polymers and so on. Glass is widely applied in micro-fluidic chip, which has good hydrophilicity, biocompatibility, chemical stability and light transmission, providing convenient conditions for cell culturing and optical detection. But its disadvantages are that it is difficult to obtain chip channels with larger depth to width ratio, and also the higher process cost. There are many kinds of organic polymers materials. Among them, PDMS materials have properties of high chemical stability, low cytotoxicity, high biological compatibility, good elasticity, and simple processing technology. In this study, we prepared the micro-fluidic chip with molding and standard wet corrosion process. Meanwhile, the channel surface of micro-fluidic chips is modified with Matrigel.
The involvement of liquid crystals in multichannel implanted neurostimulators, hearing and ENT infections, and cancer
Published in Acta Oto-Laryngologica, 2019
Chouard Claude-Henri, Christiane Binot, Jean-François Sadoc
Chemically, polymers are macromolecules constituted by the repetition of numerous subunits known as monomers; if liquid, the whole is isotropic; otherwise it is in a crystalline state, well studied by physicists. More than a century ago, new states of matter were discovered, associating the birefringence of a crystal and the fluidity of a liquid. A crystal liquid can be made of long molecules or with smaller molecules be the solvent of a polymer. Polymers can be dissolved in a solvent. In some cases, the polymers can have a liquid crystal structure depending on solvent concentration (lyotrope) or temperature (thermotrope), with a change of physical condition (temperature, solvent nature: hydrophile or oily. The global properties could be completely modified in such complex of molecules: the polymer takes on new properties, with a degree of order depending on these physical parameters. These LCs dispersed within a polymer matrix are known as PDLCs (for ‘polymer-dispersed liquid crystal’) or, more briefly, LCPs. The anisotropism of the LC makes the system birefringent.
The era of biofunctional biomaterials in orthopedics: what does the future hold?
Published in Expert Review of Medical Devices, 2018
Mubashar Rehman, Asadullah Madni, Thomas J. Webster
Carbon-based materials are widely recognized as nontoxic and non-irritant to the human body. Although different carbon-based materials have been investigated in orthopedic applications, polymeric materials have progressed due to desirable mechanical properties that can be easily tuned to match the properties of different bones and joints (Table 1). As compared to metallic alloys and ceramics, polymers are flexible, light weight, and have an elastic modulus similar to bone while resistant to corrosion and biochemical attack, and are relatively easy to fabricate [2]. Polymers are available in different compositions which makes them suitable for functionalization with other materials. PE is currently used in ultra-high-molecular-weight PE (UHMWPE) in orthopedic materials. Its unique properties include low friction as well as high wear resistance, hardness, and strength [34]. Although their wear debris was reported to induce inflammation after long-term implantation, UHMWPE remains the most suitable orthopedic material due to superior mechanical properties, biocompatibility, and ease of preparation.
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