Three-Dimensional Cross-Linking Network Coating for the Flame Retardant of Bio-Based Polyamide 56 Fabric by Weak Bonds.

Weak bonds usually make macromolecules stronger; therefore, they are often used to enhance the mechanical strength of polymers. Not enough studies have been reported on the use of weak bonds in flame retardants. A water-soluble polyelectrolyte complex composed of polyethyleneimine (PEI), sodium tripolyphosphate (STPP) and melamine (MEL) was designed and utilized to treat bio-based polyamide 56 (PA56) by a simple three-step process. It was found that weak bonds cross-linked the three compounds to a 3D network structure with MEL on the surface of the coating under mild conditions. The thermal stability and flame retardancy of PA56 fabrics were improved by the controlled coating without losing their mechanical properties. After washing 50 times, PA56 still kept good flame retardancy. The cross-linking network structure of the flame retardant enhanced both the thermal stability and durability of the fabric. STPP acted as a catalyst for the breakage of the PA56 molecular chain, PEI facilitated the char formation and MEL released non-combustible gases. The synergistic effect of all compounds was exploited by using weak bonds. This simple method of developing structures with 3D cross-linking using weak bonds provides a new strategy for the preparation of low-cost and environmentally friendly flame retardants.

Preparation of nanocellulose by a biological method from hemp stalk in contrast to the chemical method and its application on the electrospun composite film.

In this study, CNFs were provided by an efficient, unmodified, and clean biological method with enzymes and a small amount of alkali, compared to the CNCs with the chemical method involving a strong acid. To provide an accurate targeted selection for future applications, we made the following comparison by analyzing the differences in the preparation method, performance, and application performance of the two nanocelluloses. The result of this study indicated that CNFs and CNCs exhibited a crystallinity index of 58.2 and 83.5%, respectively. CNFs had a mean length (L) of 192.3 nm and a diameter (D) of 1.9 nm, and the average L and D of CNCs reached 123.6 nm and 3.7 nm, respectively. The solution viscosity of CNFs and CNCs reached 7.46 Pa s and 1.91 Pa s, respectively. CNFs and CNCs exhibited zeta potential values of -88.26 mV and -26.40 mV, respectively. The electrospun composite film of PLA-CNFs and PLA-CNCs achieved water contact angles of 138.7 and 34.5°, and the water-oil contact angle reached 24.7 and 30.5°, respectively. The breaking strength of PLA-CNFs and PLA-CNCs reached 96.07 cN and 163.23 cN, and the break elongation followed an order of PLA-CNCs (32.16%) < PLA-CNFs (34.70%). In brief, CNFs can make the composite membrane hydrophobic and with superior extension, and CNCs can make the composite membrane hydrophilic and enhance its strength. Both the composite films conformed to the non-toxic standard, and the PLA-CNFs film more significantly contributed to the cell growth, which is expected to serve as a medical material.

Green Degumming Technology of Hemp and a Comparison between Chemical and Biological Degumming.

This paper provides an efficient and environmentally friendly biochemical degumming method for hemp fiber, which can address the problems of high temperature, high pressure, and extreme pollution of the traditional chemical method and the harsh reaction conditions of biological degumming, such as a long reaction time and pH. In the biochemical method, dilute solutions of alkali pectinase lyase and chemical additives were used to process the hemp fiber and then the fiber composition and structure were investigated. A comparison of the chemical, biological, and biochemical degumming methods shows that the biochemical method can replace the chemical one causing a similar degumming effect, both being better than the biological method. The best proportion of the biochemical solution was found to be 1.5% alkali pectinase lyase, and for chemical auxiliaries the total amount of alkali was ≤0.4% and the total amount of salt was ≤0.8%. The best conditions of the biochemical degumming process were determined to be a bath ratio of 1:10, reaction temperature of 60 °C, and the time of 60 min. After degumming, the composition of the fiber was as follows: lignin 3.69%, pectin 4.09%, hemicellulose 13.34%, and cellulose 78.87%. The fiber quality index of fibers dealt by the biochemical method shows that the linear density was 4.66 dtex, length was 35.6 mm, and fracture strength was 64.5 cN/dtex, which were higher than those treated by the chemical method. This shows that the biological degumming method can be a green degumming method with higher efficiency, lower consumption, and pollution, as well as has a broad application scope.

How Adolescents and Adults Learn About Changes in the Trustworthiness of Others Through Dynamic Interaction.

Whether to trust or distrust another individual is a complex interpersonal challenge, especially when such individuals behave inconsistently. It is still unclear as to how individuals learn and adapt to fluctuations in the trustworthiness of others and how this process changes from adolescence to adulthood. To address these issues, we implemented repeated rounds of a trust game within the context of a complicated and changeable interpersonal environment. Specifically, adolescents and adults played the role of trustors who had to decide whether to invest money in two anonymous partners carrying the risk of no reciprocation. Unbeknownst to participants, these two partners had different trustworthiness profiles: one partner initially yielded a higher initial return rate (70%) while the other initially yielded a lower initial return rate (30%). Crucially, over repeated rounds, these two partners gradually changed their responses to the point where, finally, return rates were both neutral (50%). Results indicated that all participants showed less updating in the negative direction in response to good-to-neutral partners while more updating in the positive direction in response to the bad-to-neutral partner. Compared to adults, this behavioral disparity in responses to good-to-neutral and bad-to-neutral partners was less pronounced in adolescents. Based on the computational modeling approach, the potential mechanisms underlying their behavioral patterns were revealed: the higher learning rate promoted flexible adaptions in participants to untrustworthy trustees as they changed to neutral. The less pronounced distinction between good-to-neutral and bad-to-neutral partners in adolescents was related to their lower learning rate. Overall, our study extends the understanding of trust behavior to a fluctuating social context and highlights the role of social learning in social emotion and interaction.

Photothermal graphene/UiO-66-NH2 fabrics for ultrafast catalytic degradation of chemical warfare agent simulants.

Lightweight and wearable fabrics with rapid self-detoxification functions are highly desired to resist chemical warfare agents (CWAs). Metal organic frameworks (MOFs) with high specific surface area and customizability are singularly attractive because of their ability to effectively capture and catalytically degrade CWAs. Herein, photothermal graphene-based nanocomposite fabrics are designed by wet-spinning and chemical reduction of graphene oxide fibers followed by in situ growth of UiO-66-NH2. The flexible graphene fabrics decorated with UiO-66-NH2 nanoparticles exhibit an ultrafast photothermal catalytic decontamination of dimethyl 4-nitrophenyl phosphate (DMNP), a typical simulant of CWAs. The half-life of the degradation reaction decreases from 3.4 to 1.6 min under simulated solar light irradiation, a significant gain over the values reported in the literature. Furthermore, DMNP can be degraded in 20 min by the graphene/UiO-66-NH2 fabric, and even after 5 cycles the degradation efficiency still retains more than 92 %. More importantly, the photothermal conversion of graphene and its instantaneous heat transfer to the UiO-66-NH2 catalyst effectively accelerate the catalytic reaction kinetics, achieving the fast detoxification of DMNP. The combination of catalytic degradation of MOFs with photothermal conversion effect of graphene makes the lightweight and flexible fabrics promising for protection against CWAs and other pollutants.

Influence of total flavonoids derived from Choerospondias axillaris folium on aconitine-induced antiarrhythmic action and hemodynamics in Wistar rats.

It is well known that various traditional Chinese medicines produce antiarrhythmic actions. The aims of this study were to examine whether total flavones derived from Choerospondias axillaris folium (TFCF) also produced antiarrhythmic effects using a rat model of aconitine-induced arrhythmia and to compare these observations with the effects of total flavones of Choerospondias axillaris fructus (TFC). Wistar rats were orally administered TFC (0.2 g/kg) or TFCF (0.1, 0.2, or 0.4 g/kg) daily for 7 d. Subsequently, aconitine iv at 25 µg/kg was used to induce arrhythmia in these animals. Control (C) physiological saline and positive verapamil rats were also administered orally. The starting times of ventricular ectopic beats (VE), ventricular tachycardia (VT), ventricular fibrillation (VF), and heart arrest (HA) were recorded. In comparison to C, TFCF and TFC significantly prolonged the starting time of VE, VT, VF, and HA induced by aconitine. With respect to hemodynamics, TFC and high-dose TFCF were effective in reducing HR without associated changes in BP in all groups. TFC and TFCF decreased left ventricular systolic pressure (LVSP) and maximal velocity rate of ventricular pressure (+dp/dt max and -dp/dt min) with no marked effect on left ventricular end diastolic pressure (LVEDP) and -dp/dtmin. Data demonstrated that TFCF and TFC were equally effective in diminishing the aconitine-mediated arrhythmias. In addition, TFCF and TFC produced a similar reduction in HR with no accompanying change in BP. These findings indicate that the TFCF- and TFC-induced alterations may be attributed to inhibition of ventricular contraction without altering ventricular diastolic function.

Biodiesel production from rubber seed oil using poly (sodium acrylate) supporting NaOH as a water-resistant catalyst.

Poly (sodium acrylate) supporting NaOH (NaOH/NaPAA) was prepared by in situ polymerization of aqueous solution of acrylic acid with an over-neutralization by adding excess of NaOH. NaOH/NaPAA presented a promising selectivity for water absorbency and good water retention with negligible swelling capacity in the organic solvents of methanol, glycerol, rubber seed oil methyl esters, and rubber seed oil. NaOH/NaPAA catalysts showed a basic strength of 15.0

One-pot process combining transesterification and selective hydrogenation for biodiesel production from starting material of high degree of unsaturation.

A one-pot process combining transesterification and selective hydrogenation was established to produce biodiesel from hemp (Cannabis sativa L.) seed oil which is eliminated as a potential feedstock by a specification of iodine value (IV; 120 g I(2)/100g maximum) contained in EN 14214. A series of alkaline earth metal oxides and alkaline earth metal supported copper oxide were prepared and tested as catalysts. SrO supported 10 wt.% CuO showed the superior catalytic activity for transesterification with a biodiesel yield of 96% and hydrogenation with a reduced iodine value of 113 and also exhibited a promising selectivity for eliminating methyl linolenate and increasing methyl oleate without rising methyl stearate in the selective hydrogenation. The fuel properties of the selective hydrogenated methyl esters are within biodiesel specifications. Furthermore, cetane numbers and iodine values were well correlated with the compositions of the hydrogenated methyl esters according to degrees of unsaturation.