Experimental and DFT Studies on Well-Defined Odd-Even Effect in Organic Liquid Crystal Tetramers Incorporating Two Chiral Centers

: A new series of organic liquid crystal tetramers containing two symmetrical mesogenic units of 4-(4’-phenoxylimino)methyl)phenol joined by methylene –(CH2)m- spacer wherein m varied from 5 to 10 has been synthesized. The length for each of the mesogenic units was extended further via connection with two chiral entities of (S)-2- methylbutyl-4-(4’-bromobutyloxyphenyl)benzoate situated at both terminal ends. The structures of these tetramers were elucidated using elemental analysis and spectroscopic techniques (FT-IR and 1H-NMR) while the texture and the phase transition temperatures were studied using polarizing optical microscopy (POM) along with differential scanning calorimetry (DSC). All the homologues in this series are enantiotropic mesogens exhibiting oily streak texture or fan shaped texture characteristic of chiral nematic phase. The odd-even effect can be observed upon increasing the methylene spacer length. The structure-properties connectivity has demonstrated that the phase transition temperature for tetramers with even- numbered methylene units in the spacer is relatively higher in comparison with the odd- numbered members. The computational study via constraint molecular dynamics performed at the DFTB level of theory has further supported that more energy is required for the even- numbered tetramer than the odd-numbered member to undergo the structural transition from folded to extended geometries.

Towards Understanding Relationships between Tension Property and Twinning Boundaries in Magnesium Alloy

Although pre-induced {1012} twins could strengthen magnesium and its alloys, the origin of such a strengthening phenomenon remains questionable. This is because twins can simultaneously change the size of grains and the texture features of the initial material. In the present work, the effect of pre-induced {1012} twins on the tension property of an extruded magnesium alloy has been investigated through a combination of electron backscatter diffraction, transmission electron microscope, and mechanical tests. Samples with and without {1012} twinning boundaries, but possessing an almost identical texture characteristic, were prepared by pre-compression perpendicular to the extrusion direction. Subsequently, these pre-strained samples were tensioned along the extrusion direction. The results indicate that the pre-induced {1012} twinning boundaries can indeed enhance the tension strength of magnesium alloys, but only slightly. The effect is closely associated with the amount of pre-strain. Correspondingly, the possible mechanisms behind such phenomena are given and discussed.

Fabrication of Strong and Ductile AZ31 Magnesium Alloy Using High Strain Rate Multiple Forging in a Wide Temperature Range

High strain rate multiple forging (HSRMF) was successfully carried out on AZ31 magnesium alloy at a temperature range of 250–400 °C, and the microstructure, texture and mechanical properties were examined. Full recrystallized structure developed at a relatively lower strain due to the twining induced dynamic recrystallization (TDRX) mechanism, which is also responsible for the feasibility of HSRMF deformation at relative low temperature. The average grain sizes of the alloys high strain rate multiple forged (HSRMFed) to the accumulated strain of ∑Δε = 1.32 increased from 7.07 to 9.99 μm as the temperature ranged from 250 to 400 °C, i.e., the grain sizes of the HSRMFed alloy were less sensitive to temperature. The weakened basal texture characteristic of titled or double peak achieved was ascribed to the alteration of forging direction. The HSRMFed alloys demonstrated both excellent strength (UTS > 300 MPa) and good ductility (δ > 20%), which resulted from the combined effects of grain refinement and weakened basal texture. Therefore, HSRMF was an efficient technique to produce strong and ductile wrought AZ31 alloy.

Effect of liquid smoke on microbiological and physico-chemical properties of beef meatballs during storage

Meatballs beef is a processed-meat product which has distinctive texture characteristic and is classified as perishable food products. Microbiological and physico-chemical properties are essential factors in determining the quality of meat products, and one of the things affecting the quality is the interaction between smoke and food components. The objective of this study was to evaluate the effect of liquid smoke on the microbiological and physico -chemical properties of beef meatballs during storage. The research method used explanatory research with five treatments and three replications and analyzed with a regression model. Beef meatballs without the addition of liquid smoke were used as controls, while the addition of liquid smoke 1.0 %, 1.5%, 2.5%, 2.5%, and 3.0% were used as treatments. The parameters analyzed consisted of pH, total microbial number, color, and texture profile of beef meatballs. The storage time significantly has a negative effect on the pH value but has a positive effect on the total microbial number and texture parameters (hardness, springiness, cohesiveness, and gumminess). Increased liquid smoke concentrations in beef meatballs can significantly reduce microbe damage, maintain texture during storage, and increase the total color difference. Liquid smoke can be used as a natural preservative alternative, which is safe for beef meatballs. However, it must be considered about consumers' preference for the smoky aroma and flavor obtained.

Effect of the basic surface properties of woven lining fabric on printing precision and electrical performance of screen-printed conductive lines

Conductive lines are essential for the integration of electronic devices into fabrics, and their direct screen printing on fabrics is a promising, simple and low-cost method for mass-manufactured textile-based conductive lines. However, the intrinsic porous structures and texture characteristic of textiles complicate the diffusion and penetration of conductive ink, and will deteriorate the printing precision and electrical performance of conductive lines. To establish the relationship between the surface characteristics (i.e. porosity, roughness, contact angle) and printing precision as well as electrical performance, the screen-printed conductive lines on six different nylon woven lining fabrics were examined and compared. Moreover, to study the printing precision and the minimum printable line width on woven lining fabric, conductive lines with different widths were screen printed. The results showed that the fabric substrate with the smallest pore size and roughness shows a higher printing precision and lower electrical resistance of screen-printed conductive lines. Relatively, the dynamic contact angle and wetting time of ink on the surface of the fabric have a significant effect on the printing precision. Therefore, the surface structure of the fabric substrate determines to some degree the printing precision of conductive lines, the printable minimum line width and its electrical properties. It is believed that these findings will provide some important support for screen printing flexible electronic devices on woven textiles.

Impact of xanthan gum addition on phenolic acids composition and selected properties of new gluten-free maize-field bean pasta

Replacing the gluten network to produce high quality pasta is a great technological challenge. One of known solutions to the problem is the addition of xanthan gum. This paper focuses on the possibility of obtaining a new type of gluten-free maize-field bean pasta and explores the characteristics of phenolics content, antioxidant activity, cooking quality, textural and thermotropic behavior as well as the microstructure of pasta products with the various levels of added xanthan gum. The obtained results revealed that 0.25, 0.50 and 0.75% addition of xanthan gum to pasta did not have significant influence on its phenolics content and antioxidant activity, whereas 1.00% addition caused a decrease in the tested parameters. On the other hand, the opposite effect of gum addition on the cooking quality, texture characteristic and microstructure was observed. The addition of xanthan gum to the formulation improved pasta quality while reducing the leaching of its components into the cooking water. Pasta prepared with 1.00% xanthan gum showed the lowest cooking loss, the highest firmness, and the lowest adhesiveness. These results revealed a significant influence of xanthan gum content on pasta properties as confirmed by the thermal analysis and SEM microstructure observations.

An Intelligent Warning Method for Diagnosing Underwater Structural Damage

A number of intelligent warning techniques have been implemented for detecting underwater infrastructure diagnosis to partially replace human-conducted on-site inspections. However, the extensively varying real-world situation (e.g., the adverse environmental conditions, the limited sample space, and the complex defect types) can lead to challenges to the wide adoption of intelligent warning techniques. To overcome these challenges, this paper proposed an intelligent algorithm combing gray level co-occurrence matrix (GLCM) with self-organization map (SOM) for accurate diagnosis of the underwater structural damage. In order to optimize the generative criterion for GLCM construction, a triangle algorithm was proposed based on orthogonal experiments. The constructed GLCM were utilized to evaluate the texture features of the regions of interest (ROI) of micro-injury images of underwater structures and extracted damage image texture characteristic parameters. The digital feature screening (DFS) method was used to obtain the most relevant features as the input for the SOM network. According to the unique topology information of the SOM network, the classification result, recognition efficiency, parameters, such as the network layer number, hidden layer node, and learning step, were optimized. The robustness and adaptability of the proposed approach were tested on underwater structure images through the DFS method. The results showed that the proposed method revealed quite better performances and can diagnose structure damage in underwater realistic situations.

Evaluation of responses embryogenic Cycas revoluta thumb., from callus culture obtained in vitro

Processes cell differentiation and dedifferentiation are included in the development of biotechnology protocols to promote somatic embryogenesis as an alternative to the in vitro propagation of plants, somatic embryos may be an excellent strategy for both propagation and conservation of fossil species such as cycads. They were evaluated in vitro with different strategies, morphogenic responses associated with obtaining somatic embryos of C. revolute. calli of megagametophytes, subsequently subcultured in four combinations of basic salts of Murashige and Skoog (1962) MS, with the addition of benzyladenine (BA), and 2, dichlorophenoxyacetic (2,4-D) were used, and kinetin (K), and picloram. In the results, It was possible to characterize potentially embryogenic callus, evaluating the levels of both cellular differentiation, necrosis, texture and color; and increases mass or weight considered to start differentiation or proembryogenic or globular type. Calli were subcultured in a medium containing MS salts, incorporating abscisic acid (ABA) in 0, 0.38, 1.13, 3.78 and 5.67 uM doses influenced both the production and maturation of somatic embryos. Embryonic structures, presented a pink coloration characteristic strongly associated towards maturity. The effect of combinations of BA, Kin, 2,4-D, GA3 and ANA influenced the development and germination of mature somatic embryos. And the combination of 1.36 mM 2,4-D+4.44 uM BA promoted the appearance of calluses with a compact texture, characteristic related to their embryogenic potential. The purpose of this research in Cycas sp was to contribute to the study of the in vitro morphogenic responses of this group of plants. And somatic embryogenesis, will allow the obtaining and multiplication as well as its preservation of Cycas sp. Gender that is evolutionary very important