Study of the Relationship between Haze Performance and Fractal Dimension in Micro-Sized Segregated Liquid Crystals Embedded in a Polymer Matrix Consisting of a Thiol-ene Prepolymer and a Multi-Functional Acrylate

Micro-sized segregated liquid crystals (MSLCs) surrounded by a polymer medium can be used for haze film applications. When incident light passes through the MSLC film, the microsized particles act as light scattering centers. In this study, the results of the addition of a multi-functional acrylate to a commercial thiol-ene prepolymer system, as well as the morphology of (LC) droplets, fractal dimension (D), and the optical haze performance of the micro-sized segregated LCs formed by UV-initiated photopolymerization, are reported. With increasing fraction of the multi-functional acrylate within the host polymer matrix, the small scattering centers (LC droplets) also increase, giving rise to a large optical haze in the prepared film. The optical haze can be characterized by the D of the associated LC droplet morphology in the films. The optical haze and D exhibit a strong correlation; thus, a qualitative prediction of the optical haze is possible via geometric fractal analysis.

Gas Phase Lubrication Study with an Organic Friction Modifier

Friction modifier additive technologies play a crucial role in controlling friction and wear of lubricated tribological systems. Novel additives are usually evaluated using formulations of varying concentrations. It can be very difficult to understand the underlying mechanisms in those laboratory tests because of the interaction of base oil with the additives. It thus can be insightful to perform model experiments in a controllable atmosphere. This can be achieved for instance by integrating a tribometer into a vacuum system comprising in-situ surface analytical methods.In this work, a nitrogen containing organic friction modifier is adsorbed from the gas phase onto a Fe2O3 surface. Different coating thicknesses are prepared by varying the duration of the vapor deposition, so that the influence of the coating thickness on the friction behavior can be investigated. The chemical composition of the coated surfaces is also analyzed by coupling to an XPS photoelectron spectrometer.Contrary to the assumption that layers are formed, this friction modifier accumulates in droplets on the Fe2O3 surface. The number of droplets as well as the radii of droplets increase with evaporation time. The chemical composition of the additive does not change as a result of the gas phase deposition. In the friction tests, the smallest friction values are found for a very low coverage of droplets. For larger droplets, friction increases due to a capillary neck of additive that forms between the sliding surfaces and is dragged along during the friction test.Using gas phase adsorption of a nitrogen containing organic friction modifier it was possible to establish a correlation between droplet morphology and the friction behavior.

Thyroid Hormone Deficiency Modifies Hepatic Lipid Droplet Morphology and Molecular Properties in Lithogenic-Diet Supplemented Mice

Objective Thyroid hormones have been associated with a hepatic lipid lowering effect and thyroid function has been shown to play a substantial role in development of non-alcoholic fatty liver disease. Hepatic lipid droplets differ in the number, size and molecular properties depending on metabolic state or pathological condition. However, in how far thyroid hormone deficiency affects hepatic lipid droplet morphology and molecular properties is still poorly understood. Therefore, we performed a study in mice using a lithogenic diet model of steatohepatitis and modulated the thyroid hormone status. Methods Male and female three months old C57BL/6 mice were divided into a euthyroid (control), a lithogenic (litho) and a lithogenic+thyroid hormone deficient (litho+hypo) group and treated for six weeks. Hepatic transmission electron microscopy and gene expression analysis of lipid-droplet associated proteins were performed. Results Increased mean diameters of hepatic lipid droplets and a shift towards raised electron-density in lipid droplets was observed under thyroid hormone deficiency. Furthermore thyroid hormone deficiency altered hepatic expression of genes involved in lipophagy and triacylglycerol mobilization. Interestingly, while the impact of thyroid hormone deficiency on lipid droplet morphology seems to be sex-independent, hepatic lipid droplet-associated gene expression differed significantly between both sexes. Conclusion This study demonstrates that thyroid hormone deficiency alters hepatic lipid droplet morphology and hepatic gene expression of lipid droplet-associated proteins in a lithogenic diet mouse model of steatohepatitis.

HOXA5 Participates in Brown Adipose Tissue and Epaxial Skeletal Muscle Patterning and in Brown Adipocyte Differentiation

Brown adipose tissue (BAT) plays critical thermogenic, metabolic and endocrine roles in mammals, and aberrant BAT function is associated with metabolic disorders including obesity and diabetes. The major BAT depots are clustered at the neck and forelimb levels, and arise largely within the dermomyotome of somites, from a common progenitor with skeletal muscle. However, many aspects of BAT embryonic development are not well understood.Hoxa5patterns other tissues at the cervical and brachial levels, including skeletal, neural and respiratory structures. Here, we show thatHoxa5also positively regulates BAT development, while negatively regulating formation of epaxial skeletal muscle. HOXA5 protein is expressed in embryonic preadipocytes and adipocytes as early as embryonic day 12.5.Hoxa5null mutant embryos and rare, surviving adults show subtly reduced iBAT and sBAT formation, as well as aberrant marker expression, lower adipocyte density and altered lipid droplet morphology. Conversely, the epaxial muscles that arise from a common dermomyotome progenitor are expanded inHoxa5mutants. Conditional deletion ofHoxa5withMyf5/Crecan reproduce both BAT and epaxial muscle phenotypes, indicating that HOXA5 is necessary withinMyf5-positive cells for proper BAT and epaxial muscle development. However, recombinase-based lineage tracing shows thatHoxa5does not act cell-autonomously to repress skeletal muscle fate. Interestingly,Hoxa5-dependent regulation of adipose-associated transcripts is conserved in lung and diaphragm, suggesting a shared molecular role forHoxa5in multiple tissues. Together, these findings establish a role forHoxa5in embryonic BAT development.

Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System

Indium tin oxide (ITO) is widely used as a substrate for fabricating chips because of its optical transparency, favorable chemical stability, and high electrical conductivity. However, the wettability of ITO surface is neutral (the contact angle was approximately 90°) or hydrophilic. For reagent transporting and manipulation in biochip application, the surface wettability of ITO-based chips was modified to the hydrophobic or nearly hydrophobic surface to enable their use with droplets. Due to the above demand, this study used a 355-nm ultraviolet laser to fabricate a comb microstructure on ITO glass to modify the surface wettability characteristics. All of the fabrication patterns with various line width and pitch, depth, and surface roughness were employed. Subsequently, the contact angle (CA) of droplets on the ITO glass was analyzed to examine wettability and electrical performance by using the different voltages applied to the electrode. The proposed approach can succeed in the fabrication of a biochip with suitable comb-microstructure by using the optimal operating voltage and time functions for the catch droplets on ITO glass for precision medicine application. The experiment results indicated that the CA of droplets under a volume of 20 μL on flat ITO substrate was approximately 92° ± 2°; furthermore, due to its lowest surface roughness, the pattern line width and pitch of 110 μm exhibited a smaller CA variation and more favorable spherical droplet morphology, with a side and front view CA of 83° ± 1° and 78.5° ± 2.5°, respectively, while a laser scanning speed of 750 mm/s was employed. Other line width and pitch, as well as scanning speed parameters, increased the surface roughness and resulted in the surface becoming hydrophilic. In addition, to prevent droplet morphology collapse, the droplet’s electric operation voltage and driving time did not exceed 5 V and 20 s, respectively. With this method, the surface modification process can be employed to control the droplet’s CA by adjusting the line width and pitch and the laser scanning speed, especially in the neutral or nearly hydrophobic surface for droplet transporting. This enables the production of a microfluidic chip with a surface that is both light transmittance and has favorable electrical conductivity. In addition, the shape of the microfluidic chip can be directly designed and fabricated using a laser direct writing system on ITO glass, obviating the use of a mask and complicated production processes in biosensing and biomanipulation applications.

A Novel Multiscale Methodology for Simulating Droplet Morphology Evolution during Injection Molding of Polymer Blends

The morphology of polymer blends plays a critical role in determining the properties of the blends and performance of resulting injection-molded parts. However, it is currently impossible to predict the morphology evolution during injection molding and the final micro-structure of the molded parts, as the existing models for the morphology evolution of polymer blends are still limited to a few simple flow fields. To fill this gap, this paper proposed a novel model for droplet morphology evolution during the mold filling process of polymer blends by coupling the models on macro- and meso-scales. The proposed model was verified by the injection molding experiment of PP/POE blends. The predicted curve of mold cavity pressure during filling process agreed precisely with the data of the corresponding pressure sensors. On the other hand, the model successfully tracked the moving trajectory and simulated morphology evolution of the droplets during the mold-filling process. After mold-filling ended, the simulation results of the final morphology of the droplets were consistent with the observations of the scanning electron microscope (SEM) experiment. Moreover, this study revealed the underlying mechanism of the droplet morphology evolution through the force analysis on the droplet. It is validated that the present model is a qualified tool for simulating the morphology evolution of polymer blends during injection molding and predicting the final microstructure of the products.

Investigation on the droplet evaporation process on local heated substrates with different wettability

Marangoni effect is one of the critical factors in the droplet evaporation process, which is caused by surface tension gradient in the droplet interface. In this study, local heating is adopted to provide a more complicated temperature distribution on the droplet surface, and a detailed numerical investigation is carried out to address the effect of Marangoni flow on the droplet evaporation behaviour. Results show that asymmetric heat source position could result in the droplet morphology being asymmetric, especially for droplets on super-hydrophilic surfaces. The evaporation rate could be affected both by the heat source position and the droplet contact angle. When placed on a smooth substrate, the droplet will slip horizontally as a result of the asymmetric heating condition. The slipping behaviour is affected by both the heat source position and the surface wettability.

Preparation and Evaluation of Nanoemulgels Containing a Combination of Grape Seed Oil and Anisotriazine as Sunscreen

BACKGROUND: Grape seed oil contains Vitamin E which acts as skin antioxidant and natural ultraviolet (UV) absorbent and anisotriazine is used as chemical absorbent. Sun protection factor (SPF) value of the sunscreen and physical stability can be increased using a combination of grape seed oil and anisotriazine as sunscreen material and preparation by nanotechnology. AIM: The objective of this study was to prepare and evaluate physical stability and in vitro SPF value of sunscreen nanoemulgel containing grape seed oil and anisotriazine. METHODS: Nanoemulgels containing 4% grape seed oil and anisotriazine (1.6% and 3.2%) were formulated by adding 2% of Carbopol 940 gel to the optimized nanoemulsions formulation with a ratio of nanoemulsion and gel 4:1. The nanoemulgels were evaluated physical stability during storage for 12 weeks at variations of temperature, centrifugation, and cycling test. SPF values of nanoemulgels were determined by UV–visible spectrophotometric method and compared to emulgel. Droplet morphology observation of nanoemulgel using transmission electron microscope. RESULTS: The results of this study showed that sunscreen nanoemulgel containing 4% grape seed oil and 3.2% anisotriazine had average droplet size of 187.5 nm, physically stable during experiment for 12 weeks at variation of temperature and after centrifugation and cycling test, but the sunscreen emulgel showed a phase separation. The SPF of nanoemulgel containing a combination of 4% grape seed oil and 3.2%, nanoemulgel without anisotriazine, and emulgel formulation was 19.325 ± 0.232, 11.169 ± 0.113, and 11.913 ± 0.161, respectively. Transmission electron microscopy analysis of droplet morphology showed that this nanoemulgel formulation formed a spherical globule. CONCLUSION: The sunscreen nanoemulgel formulation containing combination of 4% grape seed oil and 3.2% anisotriazine more stable than sunscreen emulgel during experiment for 12 weeks at room temperature and showed the SPF value higher compared to emulgel containing 4% grape seed oil and 3.2% anisotriazine and nanoemulgel without anisotriazine.