Excellent Thermostability Research Articles

A multifunctional epoxy composites based on cellulose nanofiber/carbon nanotube aerogels: Simultaneously enhancing fire-safety, thermal conductive and photothermal performance

As 5G technology develops and electronic power density increases, preparing epoxy resin (EP) composites with excellent fire-safety, thermostability, and thermal conductivity remains challenging. Herein, hexaphenoxy cyclotriphosphazene and poly(piperazine methylphosphonic acid pentaerythritol ester) were used as synergistic flame retardants (FR) for EP. The cellulose nanofiber/carboxylated multiwalled carbon nanotubes aerogels (CCA80) were prepared and immersed into the EP and FR mixture to obtain EP/CCA80/FR composites. Compared with neat EP, the limiting oxygen index of EP/CCA80/6 wt% FR increased by 38.9 %, the total heat release and CO2 production rate decreased by 30.61 % and 39.47 %, respectively, achieving the UL-94 V-0 rating. Moreover, its thermal conductivity was 1.06 W · m−1·K−1, 457.9 % higher than neat EP, while maintaining excellent electrical insulation. Its surface temperature maintained at 94.5 °C under 1.0 kW·m−2 irradiation for 2 h, exhibiting good photothermal conversion capability and photobleaching resistance. A novel fabrication methodology of multifunctional EP composites for high-performance electronic component was proposed.

Green synthesis of Au nanoparticles by Scutellaria barbata extract for chemo-photothermal anticancer therapy

IntroductionThe combination of photothermal therapy and chemotherapy has emerged as a promising strategy for cancer treatment. The green synthesis of gold nanoparticles (Au NPs) using extracts from traditional Chinese medicine Scutellaria barbata D. Don (Scu) has revealed an economical, sustainable, and eco-friendly approach for the outstanding anticancer activities. MethodsScu extract was mixed with HAuCl4 solution to fabricate Scu-Au NPs. The synthesis process was optimized by varying the reaction temperature, reaction time, and HAuCl4 concentration. The changes in the components of Scu before and after synthesis were analyzed using the 3,5-dinitrosalicylic acid (DNS) reduction test, the rutin colorimetric method, and the Folin–Ciocalteu method. The morphology, size, and structure of Scu-Au NPs were characterized by TEM, DLS, XRD, and XPS. The photothermal characteristics induced by near-infrared (NIR) irradiation were assessed by continuously monitoring the temperature elevation. The anticancer activity and mechanisms of Scu-Au NPs were investigated using MTT assay, cell uptake studies, ROS level detection, cell apoptosis and necrosis assays, flow cytometry analysis, intracellular Caspase-3 protein activity fluorescence detection, and Western blot analysis on A549, 4T1, and RAW264.7 cells. ResultsScu-Au NPs were successfully fabricated using Scu extract as a reducing agent. The Scu-Au NPs were spherical with a size of 50 nm. During the synthesis process, the levels of reducing sugars, flavonoids, and polyphenols in the Scu extract decreased by 80.8%, 54.3%, and 70.1%, respectively. Scu-Au NPs demonstrated excellent photothermal responsiveness, thermostability, and biocompatibility. For chemo-photothermal anticancer therapy, the cytotoxicity of Scu-Au NPs on 4T1 cells reached approximately 85% upon exposure to 808 nm NIR irradiation. The anticancer activity was attributed to the induction of apoptosis and necrosis, achieved by increasing intracellular ROS levels, causing cell cycle arrest at the S phase, and modulating the expression of apoptosis-related proteins. DiscussionOur synthesized Scu-Au NPs exhibit favorable photothermal conversion characteristics, demonstrating excellent therapeutic efficacy and safety for cancer treatment.

Facile synthesis of N-doped graphene quantum dots as a fluorescent sensor for Cr(vi) and folic acid detection.

The development of stable fluorescent sensors for toxic pollutants and drugs is meaningful to the environment and public health. In this work, nitrogen-doped graphene quantum dots (N-GQDs) were facially synthesized by a one-step hydrothermal method using soluble starch and l-arginine as carbon and nitrogen sources in pure water at 190 °C for 4 h. The as-synthesized N-GQDs were well characterized and displayed blue fluorescence emission at 445 nm with excellent pH stability, salt tolerance, thermostability, photobleaching resistance and reproducibility. Moreover, N-GQDs could serve as an "on-off" sensor for selective detection of Cr(vi) and folic acid with low detection limit (0.80 and 2.1 μM), good linear correlation over wide linear range (0-50 μM and 0-200 μM) as well as short response time (<10 s). The practical applications of N-GQDs for Cr(vi) and folic acid detection in actual samples were further investigated and showed acceptable recoveries (92-105%) with relative standard deviations less than 5%. These results indicated that this N-GQDs-based sensor could be a potential alternative for Cr(vi) and folic acid detection in the fields of environmental monitoring and drug analysis.

Thermally stable low-shrinkage monolithic SiC aerogels for heat insulation

In recent years, SiC aerogels have attracted considerable research interest owing to their excellent high-temperature resistance. It is crucial to research and improve the thermal stability of SiC aerogels under long and multiple heat treatments. Herein, we develop a series of monolithic SiC aerogels with a density of 0.23–0.28 g cm−3, low-thermal linear shrinkage of 21%–27 %, and high compressive strength of 0.38–0.60 MPa by designing a novel core–net structure. The resulting aerogels exhibit excellent thermal insulation thermostability and high-temperature reusability. Thermal conductivities of 0.0455–0.0678 W K−1 m−1 and 0.0934–0.1313 W K−1 m−1 were achieved at 40 °C and 900 °C, respectively. Following three consecutive heat treatments using a butane spray gun for 2000 s, the macromorphology exhibited no change, and the backside temperature was 230 °C. The results demonstrate an effective solution to reuse aerogels as long-lasting high-temperature insulation materials.

Cloning and characterization of a hyaluronate lyase EsHyl8 from Escherichia sp. A99

Hyaluronidase, an enzyme that degrades hyaluronic acid (HA), is utilized in clinical settings to facilitate drug diffusion, manage extravasation, and address injection-related complications linked to HA-based fillers. In this study, a novel hyaluronate lyase EsHyl8 was cloned, expressed, and characterized from Escherichia sp. A99 of human intestinal origin. This lyase belongs to polysaccharide lyase (PL) family 8, and showed specific activity towards HA. EsHyl8 exhibited optimal degradation at 40 °C and pH 6.0. EsHyl8 exhibited a high activity of 376.32 U/mg among hyaluronidases of human gut microorganisms. EsHyl8 was stable at 37 °C and remained about 70 % of activity after incubation at 37 °C for 24 h, demonstrating excellent thermostability. The activity of EsHyl8 was inhibited by Zn2+, Cu2+, Fe3+, and SDS. EsHyl8 was an endo-type enzyme whose end-product was unsaturated disaccharide. This study enhances our understanding of hyaluronidases from human gut microorganisms.

Recyclable azine polyurethane thermosets and carbon fiber reinforced composites with excellent thermostability and mechanical properties

Carbon fiber reinforced composites (CFRCs) have received increasingly concerns and widely used in high-end applications, owing to their outstanding mechanical properties. Most of the polymers used in CFRCs were thermosets. However, a large number of applications brought enormous wastes due to the stable structure of thermosets which is difficult to degrade or recycle. CFRCs based on dynamic covalent polymers (DCPs) were developed to resolve the recycling problem. Polyurethanes were used for fabricating CFRCs applied in energy absorbing materials, vehicle interiors, sporting goods, and constructing materials, owing to excellent toughness, bonding abilities and low VOCs. Although some recyclable PU CFRCs were developed to resolve the recycling of CFs, there remain the problems of excess catalysts, low chemical resistance or thermostability due to the dynamic feature of DCPs. Herein, a series of azine polyurethane thermosets (APUTs) were prepared from hexamethylene diisocyanate (HDI) trimer and dihydroxy azines with different lengths of carbon chains. The resulting APUTs displayed excellent thermal stabilities with all Td, 5 % exceeding 320 °C, owing to high exchange temperature of azine moieties and high crosslinking density. APUTs-6 showed the highest tensile strength of 36.72 ± 1.18 MPa. APUTs-6 could be easily degraded in 0.1 M acetone/water solution at 50 °C. APUTs-6 showed excellent reprocessing properties and tensile strength could maintain 83.1 % of its initial one. The APUTs-6/CFs composites exhibited excellent mechanical properties, chemical resistance and recyclability. CFs could be readily recycled by acid degradation and maintain excellent mechanical properties. The tensile strength of recycled composites could recover 94.36 % of the original one after two times of recycling. The recovery ratio of tensile strength of recycled CF filaments was 95.7 %. The application of phenyl azine provided a feasible solution for the industrialization of recyclable CFRCs.

Dual‐Network Assembled Nanopaper towards Extremely Harsh Conditions

AbstractAramid nanofibers (ANFs) exhibit desirable lightweight and excellent properties, while their strength has to be sacrificed to further improve their electrical insulation and fire resistance so as to meet the special demands of extreme environments. Herein, Zylon nanofibers (ZNFs) with analogous structure compatibility but superior performance are employed to construct an assembled dual‐network structure to improve the overall properties of ANFs. A facile in situ structure restoration (ISSR) strategy is proposed to achieve ZNF aqueous dispersion for the first time by deprotonation of ZNFs, which significantly avoids the corrosive acid system and facilitates the papermaking process. The composite ANF@ZNF nanopaper exhibits incredible tensile strength (233 MPa) and toughness (14.7 MJ m−3), increased by 108% and 584% compared with pure ANF nanopaper due to the dense entangled dual‐network and tremendous hydrogen bonds. Moreover, it presents superior breakdown strength of ≈128 kV mm−1, which is 6 times higher than that of commercial Nomex T410 insulation paper with a thickness of 50 µm. Besides, it exhibits surprising flame resistance (endure 1000 °C burning) ascribed to the excellent thermostability of ZNFs. This work provides promising possibilities for expanding the applications of aramid‐based composites for advanced electrical insulation and thermal protection in extremely harsh conditions.

Low-density, large-sized SiCnw/SiOC composite aerogels with excellent thermal insulation, microwave absorption, and thermostability

Polymer-derived ceramic aerogels are promising materials for thermal insulation and microwave absorption in harsh environments because their microstructures can be controlled at the molecular level. Silicon oxycarbide (SiOC) aerogels are considered as potential high-temperature electromagnetic wave (EMW) absorbers, but their application range is limited by complex preparation process and unsatisfactory microwave-absorption performance. This paper reports a new SiC nanowire/SiOC composite aerogel (SCA) synthesized through the sol–gel process, environmental pressure drying, and high-temperature treatment. The SCA performance is adjusted by controlling the ratio of SiC nanowires, obtaining low thermal conductivities (0.04–0.042 W m−1 K−1) and excellent mechanical properties (4.37–5.45 MPa). Increasing the SiC nanowire content gradually increases the EMW absorption capacity of SCA. The optimal reflection loss is −53.64 dB and the effective absorption bandwidth is 3.88 GHz, substantially higher than that of SiOC aerogels. This high performance is mainly attributable to the appropriate impedance matching characteristics and strong polarization loss ability. Moreover, the performance of the composite aerogels was retained after long-term treatment in an air environment at 800 °C. SCA also exhibits excellent high-temperature insulation and flame retardancy. Owing to its light weight, strong microwave-absorption ability, good thermal insulation performance, and oxidation resistance, SCA is a highly promising alternative material for use in extreme environments.

A recombinant amylomaltase from Thermus thermophilus STB20 can tailor the macromolecular characteristics of tapioca starch through its transglycosylation activity

Amylomaltase (AM) is a transglucosylase known for producing glucans exclusively with α-1,4 linkages, which is widely used in the industries for modification of starch. In this paper, a study was conducted to investigate both the characteristics of recombinant amylomaltase from Thermus thermophilus STB20 (TtAM) and its impact on the fine structure of tapioca starch. The TtAM showed an excellent thermostability and a high affinity for larger molecular substrates. Changes in the molecular characteristics of tapioca starch were discussed in terms of chain length distribution (CLD) and molecular weight distribution (Mw) under different enzyme dosages and reaction times. The TtAM degraded amylose, which was transferred to short side chains (DP 11-26) of amylopectin, thereby extending short side chains into longer chains (DP >26). The Mw of TtAM-treated starches initially increased and then decreased. With increasing enzyme dosage and reaction time, the TtAM facilitated hydrolysis activities, reducing the proportion of long side chains, which led to increase the dextrose equivalent (DE) value. Cycloamylose (DP 8 - 33) was generated during the modification process, reflecting a diversified range of the enzyme products, and resulting in a polymodal distribution profile in the Mw. These findings potentially broaden the utilization of TtAM in the production of starch conversion products, indicating that novel starch-based derivatives with tailor-made structures can be obtained by controlling the enzyme dosages and reaction times.

Robust-flexible and highly-thermostable polyimide-silica aerogels with adjustable fiber skeleton structure for efficient aerospace thermal protection

The rapid growth of the aerospace industry presents significant challenges in developing lightweight and flexible thermal protective materials for spacecraft and related equipment. One longstanding challenge has been the preparation of high-thermostable and highly flexible aerogels, which limits their practical application in flexible thermal protection. In this work, through a rational 'chain-sphere' dual-combination structure design, polyimide-silica aerogels with integrated properties of the adjustable aerogel-fiber skeleton structure, robust flexibility and high thermostable have been prepared. By incorporating 2,2-dimethylbenzidine (DMBZ), we achieve a more solid aerogel network. The aerogel membrane retains its original shape without creases or cracks even after undergoing 500 folding and unfolding tests. Additionally, the silicon nanoparticles surrounding the aerogel exhibit superior performance at high temperatures. The unique structure and components of the composite enable it to possess lightweight (0.075–0.11 g/cm−3), low thermal shrinkage (300℃∼6 %), excellent thermostability (95 % weight retention at 474℃∼557℃), and promising thermal insulating performance below 600℃. The integrated performances of the aerogel make it suitable for high-temperature thermal protection applications that require both efficient thermal insulation and robust flexibility.

Hybridizing carbonate and ether at molecular scales for high-energy and high-safety lithium metal batteries

Commonly-used ether and carbonate electrolytes show distinct advantages in active lithium-metal anode and high-voltage cathode, respectively. While these complementary characteristics hold promise for energy-dense lithium metal batteries, such synergy cannot be realized solely through physical blending. Herein, a linear functionalized solvent, bis(2-methoxyethyl) carbonate (BMC), is conceived by intramolecularly hybridizing ethers and carbonates. The integration of the electron-donating ether group with the electron-withdrawing carbonate group can rationalizes the charge distribution, imparting BMC with notable oxidative/reductive stability and relatively weak solvation ability. Furthermore, BMC also offers advantages including the ability to slightly dissolve LiNO3, excellent thermostability and nonflammability. Consequently, the optimized BMC-based electrolyte, even with typical concentrations in the single solvent, demonstrates high-voltage tolerance (4.4 V) and impressive Li plating/stripping Coulombic efficiency (99.4%). Moreover, it fulfills practical lithium metal batteries with satisfactory cycling performance and exceptional tolerance towards thermal/mechanical abuse, showcasing its suitability for safe high-energy lithium metal batteries.

Design and Verification of Thermosetting Benzoxazoles with Excellent Dielectric Properties and Thermostability via the Materials Genome Approach (MGA)

Design and Verification of Thermosetting Benzoxazoles with Excellent Dielectric Properties and Thermostability via the Materials Genome Approach (MGA)

Bifunctionalized polyamides based on quinoxaline structure for durable electrochromic display and memory storage

With the aim to obtain multifunctional durable electrochromic (EC) devices, we propose an effective strategy by introducing weak electron acceptor segment with suitable bandgap and oxidation potential. A series of quinoxaline-based units polyamides (PAs) (denoted as T2BPA-CA, T2BPA-OA, T2BPA-TP, and T2BPA-SA) were prepared from a novel donor–acceptor-donor (D-A-D) type diamine with weak electron acceptor quinoxaline and connected with two methoxyl-substituted donor triphenylamine, 10,13-bis[4-aminophenyl (4-methoxyphenyl) amino]-dibenzo[a,c]phenazine, and four dicarboxylic acids, which are high soluble in various organic solvents and exhibit excellent thermostability. Furthermore, the T2BPA-SA thin film exhibits excellent EC performance with outstanding optical contrast (50 %), high coloration efficiency (230 cm2 C−1) and impressive cycle stability (optical contrast remains 80 % over 1400 cycles) in the NIR range. Meanwhile, all of these PAs are served as memristors and exhibit typical nonvolatile ternary memory, realizing an accessible threshold voltage of −0.65 V, a retention time of more than104 s and high current switch ratio (103.52:102.43:1). Overall, this work implies the great potential of these PAs in EC displays and memory storage devices.

Tunable durian seed gum-derived eutectogel as a novel coating material: Rheological, thermal, textural and barrier properties for enhanced food preservation

As a promising green and sustainable coating material, gum was extracted from durian seed to produce eutectogel, which the properties were tunable using natural deep eutectic solvent (NADES). Ten different eutectogels were successfully synthesized using durian seed gum (DSG) and xanthan gum (XG) gelators at different composition (5, 10, 15 %) to gel choline chloride-glucose (1:1), choline chloride-fructose (1:2) and betaine-glucose-water (1:1:1) NADESs. Results revealed that eutectogel was non-Newtonian and weak gel material with excellent thermostability up to 200 °C. When the gum content increased, the resulted eutectogel showed higher viscosity, yield stress, hardness, gumminess, adhesiveness, and weight holding capacity. In overall, choline chloride-fructose (1:2) NADES and 10 % of DSG formed an excellent eutectogel which remained stable and compatible upon 12 weeks of storage. It displayed superior viscoelastic, texture, gases and moisture barrier properties which were beneficial for food coating application. This eutectogel was able to extend the shelf life of fresh-cut apples during storage with lower weight loss and higher total phenolic content (TPC). The potential future of this well-characterized tunable DSG-derived eutectogel includes, but not limited to, food and pharmaceutical industries, smart sensing, flexible wearable electronics, water purification, supercapacitors and batteries.

One-pot sustainable synthesis of glucosylglycerate from starch and glycerol through artificial in vitro enzymatic cascade

Glucosylglycerate (R-2-O-α-D-glucopyranosyl-glycerate, GG) is a negatively charged compatible solution with versatile functions. Here, an artificial in vitro enzymatic cascade was designed to feasibly and sustainably produce GG from affordable starch and glycerol. First, Spirochaeta thermophila glucosylglycerate phosphorylase (GGP) was carefully selected because of its excellent heterologous expression, specific activity, and thermostability. The optimized two-enzyme cascade, consisting of alpha-glucan phosphorylase (αGP) and GGP, achieved a remarkable 81 % conversion rate from maltodextrin and D-glycerate. Scaling up this cascade resulted in a practical concentration of 58 g/L GG with a 62 % conversion rate based on the added D-glycerate. Additionally, the production of GG from inexpensive starch and glycerol in one-pot using artificial four-enzyme cascade was successfully implemented, which integrates alditol oxidase and catalase with αGP and GGP. Collectively, this sustainable enzymatic cascade demonstrates the feasibility of the practical synthesis of GG and has the potential to produce other glycosides using the phosphorylase-and-phosphorylase paradigm.

Characterization of a Novel Hyperthermophilic GH1 β-Glucosidase from Acidilobus sp. and Its Application in the Hydrolysis of Soybean Isoflavone Glycosides.

A putative β-glucosidase gene, BglAc, was amplified from Acidilobus sp. through metagenome database sampling from a hot spring in Yellowstone National Park. BglAc is composed of 485 amino acid residues and bioinformatics analysis showed that it belongs to the GH1 family of β-glucosidases. The gene was successfully expressed in Escherichia coli with a molecular weight of approximately 55.3 kDa. The purified recombinant enzyme showed the maximum activity using p-nitrophenyl-β-D-glucopyranoside (pNPG) as the substrate at optimal pH 5.0 and 100 °C. BglAc exhibited extraordinary thermostability, and its half-life at 90 °C was 6 h. The specific activity, Km, Vmax, and Kcat/Km of BglAc toward pNPG were 357.62 U mg-1, 3.41 mM, 474.0 μmol min-1·mg-1, and 122.7 s-1mM-1. BglAc exhibited the characteristic of glucose tolerance, and the inhibition constant Ki was 180.0 mM. Furthermore, a significant ethanol tolerance was observed, retaining 96% relative activity at 10% ethanol, and even 78% at 20% ethanol, suggesting BglAc as a promising enzyme for cellulose saccharification. BglAc also had a strong ability to convert the major soybean isoflavone glycosides (daidzin, genistin, and glycitin) into their corresponding aglycones. Overall, BglAc was actually a new β-glucosidase with excellent thermostability, ethanol tolerance, and glycoside hydrolysis ability, indicating its wide prospects for applications in the food industry, animal feed, and lignocellulosic biomass degradation.

A Fusion of Taq DNA Polymerase with the CL7 Protein from Escherichia coli Remarkably Improves DNA Amplification.

DNA polymerases are important enzymes that synthesize DNA molecules and therefore are critical to various scientific fields as essential components of in vitro DNA synthesis reactions, including PCR. Modern diagnostics, molecular biology, and genetic engineering require DNA polymerases with improved performance. This study aimed to obtain and characterize a new CL7-Taq fusion DNA polymerase, in which the DNA coding sequence of Taq DNA polymerase was fused with that of CL7, a variant of CE7 (Colicin E7 DNase) from Escherichia coli. The resulting novel recombinant open reading frame was cloned and expressed in E. coli. The recombinant CL7-Taq protein exhibited excellent thermostability, extension rate, sensitivity, and resistance to PCR inhibitors. Our results showed that the sensitivity of CL7-Taq DNA polymerase was 100-fold higher than that of wild-type Taq, which required a template concentration of at least 1.8 × 105 nM. Moreover, the extension rate of CL7-Taq was 4 kb/min, which remarkably exceeded the rate of Taq DNA polymerase (2 kb/min). Furthermore, the CL7 fusion protein showed increased resistance to inhibitors of DNA amplification, including lactoferrin, heparin, and blood. Single-cope human genomic targets were readily available from whole blood, and pretreatment to purify the template DNA was not required. Thus, this is a novel enzyme that improved the properties of Taq DNA polymerase, and thus may have wide application in molecular biology and diagnostics.

Preparation and characterization of multipurpose polypropylene composite with outstanding flame retardancy and antistatic property

AbstractTo enhance the safety grade and broaden the application scope of polypropylene in coal mines, the calcium alginate@ammonium polyphosphate@graphite microsheet (CA@APP@GM) had been synthesized and introduced into the polypropylene (PP) material to endow excellent flame retardancy, antistatic characteristics, thermostability, combustion behavior, and mechanical performance. Physical characterizations on the chemical composition and microstructure of both the gaseous and condensed phase products indicated that the phosphorus‐containing compounds were found in the char residue which were beneficial to accelerate the charring reaction to terminate the mass and heat transfer process. Hence, the CA@APP@GM executed the condensed‐phase flame‐retardant mechanism to enhance the fire resistance of PP matrix. Consequently, it is believed that the CA@APP@GM, with its remarkable flame retardancy and antistatic properties, has the potential to significantly expand the range of applications for PP materials in coal mines.

Identification of a novel thermostable transaminase and its application in L-phosphinothricin biosynthesis

Transaminase (TA) is a crucial biocatalyst for enantioselective production of the herbicide L-phosphinothricin (L-PPT). The use of enzymatic cascades has been shown to effectively overcome the unfavorable thermodynamic equilibrium of TA-catalyzed transamination reaction, also increasing demand for TA stability. In this work, a novel thermostable transaminase (PtTA) from Pseudomonas thermotolerans was mined and characterized. The PtTA showed a high specific activity (28.63 U/mg) towards 2‐oxo‐4‐[(hydroxy)(methyl)phosphinoyl]butyric acid (PPO), with excellent thermostability and substrate tolerance. Two cascade systems driven by PtTA were developed for L-PPT biosynthesis, including asymmetric synthesis of L-PPT from PPO and deracemization of D, L-PPT. For the asymmetric synthesis of L-PPT from PPO, a three-enzyme cascade was constructed as a recombinant Escherichia coli (E. coli G), by co-expressing PtTA, glutamate dehydrogenase (GluDH) and D-glucose dehydrogenase (GDH). Complete conversion of 400 mM PPO was achieved using only 40 mM amino donor L-glutamate. Furthermore, by coupling D-amino acid aminotransferase (Ym DAAT) from Bacillus sp. YM‐1 and PtTA, a two-transaminase cascade was developed for the one-pot deracemization of D, L-PPT. Under the highest reported substrate concentration (800 mM D, L-PPT), a 90.43% L-PPT yield was realized. The superior catalytic performance of the PtTA-driven cascade demonstrated that the thermodynamic limitation was overcome, highlighting its application prospect for L-PPT biosynthesis.Key points• A novel thermostable transaminase was mined for L-phosphinothricin biosynthesis.• The asymmetric synthesis of L-phosphinothricin was achieved via a three-enzyme cascade.• Development of a two-transaminase cascade for D, L-phosphinothricin deracemization.

Laminated composite fabricated using high-performance polyamine thermoset: Ultra heat resistance and excellent mechanical property

Developing polymer composites that can work in harsh environment are important for advancing materials industry. However, the composites generally based-on epoxy or phenolics resins that can endure both extremely high and low temperature are still rather limited. In this work, melamine-hexamethylenediamine (MH) thermoset which is structurally different from conventional matrices was used as matrix resin for woven glass fiber reinforced MH (GFRMH) laminated composite. Owing to the excellent thermostability (Td ≈ 460 °C) and interfacial compatibility of the MH matrix, the fabricated composites exhibited exceptional resistance to extreme temperature and mechanical performances, which are superior to that of the representative commercial epoxy-based composites. Particularly, the heat deflection temperature (HDT) of GFRMH was above 300 °C which is much higher than that of the representative high-performance commercial composites (220–270 °C). Moreover, GFRMH composite exhibited excellent retainability even at 425 °C while severe carbonization and delamination occurred to all the selected commercial products. Further, the GFRMH laminate exhibited flexural strength of 541 MPa at room temperature, higher than that of the commercial products by 80–160 MPa. Remarkably, the flexural strength increased to 852 MPa at 77 K without declining of toughness, suggesting the excellent resistance to cryogenic temperature. In summary, the results of the study disclosed the suitability of MH resin as a new matrix of glass fiber reinforced engineering materials.