Bio-based phytic acid/amino acid complex coating for antimicrobial and flame-retardant cotton fabrics.

Here, a novel multifunctional coating containing bio-based phytic acid (PA), L-glutamic acid (L-Glu), and trimesoyl chloride (TMC) is constructed by a simple soaking strategy, giving cotton fabrics excellent flame retardancy, washability, and antibacterial properties. The coating layer on the cotton surface was prepared via the electrostatic and hydrogen bonding between PA and L-Glu, accompanied by the interface polymerization between PA, L-Glu, and TMC. Among them, the limiting oxygen index value of the treated cotton fabrics (C2 and C2-TMC) was as high as 40 %. During the vertical flammability test, both C2 and C2-TMC cotton showed self-extinguished behavior with a short damaged length (≤50 mm). Remarkably, the LOI of C2-TMC sustained a high value (30 %) even after 300 laundering cycles, maintaining its self-extinguishing behavior in the vertical combustion test. Additionally, in the cone calorimetry test, peak heat release rate and total heat release of treated cotton were lower than control cotton. Surprisingly, after 30 or 60 laundering cycles, the C2-TMC cotton exhibited excellent antibacterial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans due to the continuous exposure of PA and L-Glu. Moreover, the coating layer on the cotton surface had little impact on the mechanical properties and feel of the fabric.

A novel P/N/Si/Zn-containing hybrid flame retardant for enhancing flame retardancy and smoke suppression of epoxy resins.

Currently, additively efficient flame retardants are being developed to enhance the smoke suppression, flame retardancy, and thermal properties of composite materials. To this end, the current study designed and prepared a novel P/N/Si/Zn-containing organic-inorganic hybrid denoted as APHZ. Its inorganic part was 2-methylimidazole zinc salt (ZIF-8), which improved its smoke suppression and catalytic carbonization. The organic part (P/N/Si-containing compound) promoted its flame retardancy and interfacial compatibility between APHZ and epoxy resin (EP). The test results revealed that EP/APHZ-3 composites achieved a V-0 rating and a notable LOI value of 30.7% when introducing 3 wt% APHZ into the EP matrix. Cone calorimetry tests (CCT) further demonstrated that the average heat release rate (av-HRR), total smoke production (TSP), and CO production (COP) of EP/APHZ-3 were reduced by 23.3%, 14.0%, and 21.1%, respectively. Meanwhile, the char residual was increased by 60.6%, as compared to pure EP. Furthermore, the flame-retardant mechanism of EP/APHZ composites was investigated by the XPS, TG-FTIR, and Raman spectroscopy techniques. The observed synergistic effect of the imidazole skeleton ZIF-8 and P/N/Si-containing compound in APHZ facilitated the generation of a dense multi-element char layer, with the condensed phase flame-retardant mechanism playing a dominant role. These findings contribute to developing and designing high-performance flame-retardant EP.

Neottiamaolanensis, a replacement name for Neottiabifida M.N.Wang (Orchidaceae).

According to Articles 53.1 of the International Code of Nomenclature for Algae, Fungi, and Plants (Shenzhen Code), Neottiabifida M.N.Wang (as 'bifidus'; PhytoKeys 229: 222, 2023) is an illegitimate name, and hence a new name Neottiamaolanensis M. N. Wang is proposed here.

Construction of hierarchical SiO2 microcapsule towards flame retardation, low toxicity and mechanical enhancement of epoxy resins.

A novel approach for improving the flame retardancy, smoke suppression and mechanical properties of epoxy resins (EPs) has been proposed by incorporating functionalized hollow mesoporous silica microcapsules (SHP) loaded with phosphorous silane flame retardants (SCA) and coated with polydopamine (PDA) and transition metals. The proposed approach involves a multi-level structure that combines several mechanisms to enhance the flame-retardant properties of EP. The physical barrier provided by silica serves to impede heat and mass transfer during combustion, while the catalytic carbonization effect of phosphorus and transition metals promotes the formation of a protective char layer, which acts as a barrier to further flame propagation. Incorporating a low loading amount of 3 wt% SHP into the epoxy matrix resulted in EP/SHP-3 composites with significantly improved flame retardancy, as evidenced by a limiting oxygen index of 31.5% and a V-1 rating, in contrast to the values obtained for unmodified EP, which were 23.8% and no rating, respectively. In addition, cone calorimeter test (CCT) results indicated that the total heat release, peak heat release rate and total smoke production of EP/SHP-3 decreased by 18.2%, 25.2% and 18.4%, respectively. Moreover, the improved interfacial compatibility facilitated by polydopamine assists in the dispersion and compatibility of the SHP with the epoxy matrix, leading to better mechanical properties. Herein, the addition of 1 wt% SHP to EP significantly improved its mechanical performance, with a 16.7% increase in tensile strength and a 19.2% increase in impact strength. The design of the multi-level structural approach has the potential to provide new ideas for the simultaneous improvement of fire safety as well as mechanical properties of polymers.

Neottiabifidus (Orchidaceae, Epidendroideae, Neottieae), a new mycoheterotrophic species from Guizhou, China.

Neottiabifidus, a new mycoheterotrophic orchid, found in Maolan National Nature Reserve in Guizhou Province, China, is described and illustrated here. The new species is close to N.nidus-avis, N.kiusiana and N.papilligera but differs in having a finely pubescent rachis with fewer flowers, a finely pubescent pedicel, and a fishtail-shaped lip that is deeply bilobed to the middle of the lip, with the lobes diverging at an acute angle (45°) to each other and mesochile with many papillae. Additionally, N.bifidus is well supported as a new species by molecular phylogenetic results based on ITS and chloroplast genome. The chloroplast genome of the novelty, which contains an LSC region of 33,819 bp, SSC region of 5,312 bp and IRs of 46,762 bp was assembled and annotated. A key to mycoheterotrophic Neottia species in China is also provided.

Preparation of Naphthalene-Based Flame Retardant for High Fire Safety and Smoke Suppression of Epoxy Resin.

One of the current challenges in the development of flame retardants is the preparation of an environmentally friendly multi-element synergistic flame retardant to improve the flame retardancy, mechanical performance, and thermal performance of composites. This study synthesized an organic flame retardant (APH) using (3-aminopropyl) triethoxysilane (KH-550), 1,4-phthalaadehyde, 1,5-diaminonaphthalene, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials, through the Kabachnik-Fields reaction. Adding APH to epoxy resin (EP) composites could greatly improve their flame retardancy. For instance, UL-94 with 4 wt% APH/EP reached the V-0 rating and had an LOI as high as 31.2%. Additionally, the peak heat release rate (PHRR), average heat release rate (AvHRR), total heat release (THR), and total smoke produced (TSP) of 4% APH/EP were 34.1%, 31.8%, 15.2%, and 38.4% lower than EP, respectively. The addition of APH improved the mechanical performance and thermal performance of the composites. After adding 1% APH, the impact strength increased by 15.0%, which was attributed to the good compatibility between APH and EP. The TG and DSC analyses revealed that the APH/EP composites that incorporated rigid naphthalene ring groups had higher glass transition temperatures (Tg) and a higher amount of char residue (C700). The pyrolysis products of APH/EP were systematically investigated, and the results revealed that flame retardancy of APH was realized by the condensed-phase mechanism. APH has good compatibility with EP, excellent thermal performance, enhanced mechanical performance and rational flame retardancy, and the combustion products of the as-prepared composites complied with the green and environmental protection standards which are also broadly applied in industry.

Design of P-decorated POSS towards flame-retardant, mechanically-strong, tough and transparent epoxy resins.

Epoxy resins (EPs) are known for their durability, strength, and adhesive properties, which make them a versatile and popular material for use in a variety of applications, including chemical anticorrosion, small electronic devices, etc. However, EP is highly flammable due to its chemical nature. In this study, phosphorus-containing organic-inorganic hybrid flame retardant (APOP) was synthesized by introducing 9, 10-dihydro-9-oxa-10­phosphaphenathrene (DOPO) into cage-like octaminopropyl silsesquioxane (OA-POSS) via Schiff base reaction. The improved flame retardancy of EP was achieved by combining the physical barrier of inorganic Si-O-Si with the flame-retardant capability of phosphaphenanthrene. EP composites containing 3 wt% APOP passed the V-1 rating with a value of LOI of 30.1% and showed an apparent reduction in smoke release. Additionally, the combination of the inorganic structure and the flexible aliphatic segment in the hybrid flame retardant provides EP with molecular reinforcement, while the abundance of amino groups facilitates a good interface compatibility and outstanding transparency. Accordingly, EP containing 3 wt% APOP increased in tensile strength, impact strength, and flexural strength by 66.0 %, 78.6 %, and 32.3 %, respectively. The EP/APOP composites had a bending angle lower than 90°, and their successful transition to a tough material highlights the potential of this innovative combination of the inorganic structure and the flexible aliphatic segment. In addition, the relevant flame-retardant mechanism revealed that the APOP promoted the formation of a hybrid char layer containing P/N/Si for EP and produced phosphorus-containing fragments during combustion, showing flame-retardant effects in both condensed and vapor phases. This research offers innovative solutions for reconciling flame retardancy & mechanical performances and strength & toughness for polymers.

Growth of copper organophosphate nanosheets on graphene oxide to improve fire safety and mechanical strength of epoxy resins.

With the high integration of electronic products in our daily life, high-performance epoxy resins (EP) with excellent flame retardancy, smoke suppression, and mechanical strength are highly desired for applications. In this study, copper organophosphate nanosheets were evenly grown on the surface of graphene oxide (GO) via a self-assembly process based on coordination bonding and electrostatic interactions. The resultant nanohybrid endowed EP with satisfactory flame retardant effect and improved mechanical properties. Incorporating functionalized nanosheets of merely 1 wt% loading, the impact strength of the EP nanocomposites improved by 147% when compared to 1% EP-GO. Additionally, the nanosheets inhibited the smoke and heat release of EP, and the limiting oxygen value of EP-EGOPC reached ∼29%. The mechanism analysis verified that the existence of organophosphate and copper-containing components associated with the physical barrier of GO promoted the hybrid aromatization of the char layer, thereby improving the fire safety of epoxy matrix. This research offers a new interfacial method for designing functional nanosheets with good interface compatibility and high flame-retardant efficiency in polymers.

Interfacial engineering to construct P-loaded hollow nanohybrids for flame-retardant and high-performance epoxy resins.

Nano flame retardants, as one of the key flame retardants in recent years, have been limited by poor efficiency and weak compatibility. In this study, we propose an interfacial hollow engineering strategy to tackle this problem by assembling P-phytic acid into the hollow cavity of mesoporous SiO2 grafted with a polydopamine transition metal. In this design, the grafted polydopamine-metal coatings on the hybrids can greatly improve their interface compatibility with the polymer matrix, while the loaded phytic acid in the cavity contributes to enhance flame retardancy. Consequently, the resultant hierarchical P-loaded nanohybrids show both high flame retardancy and mechanical reinforcement for the polymer. Taking epoxy resin (EP, a typical thermosetting resin used in large quantities) as a representative, at only 1 wt% loading of the nanohybrids, the impact strength of the nanocomposites improved by 35.7% compared to pure EP. Remarkably, the hybrids can simultaneously endow EP with high flame retardancy (low heat release rate) and satisfactory smoke inhibition. Additionally, the flame-retardant mechanism analysis confirmed that the nanohybrid had a better catalytic carbonization effect on promoting the highly graphitized carbon layer, thereby suppressing the fire hazard of epoxy resins. This research offers a new interfacial hollow engineering method for the construct and design of high-performance EP with nanohybrids.

Phylogenetic incongruence in Cymbidium orchids.

Cymbidium, which includes approximately 80 species, is one of the most ornamental and cultivated orchid genera. However, a lack of markers and sparse sampling have posed great challenges to resolving the phylogenetic relationships within the genus. In the present study, we reconstructed the phylogenetic relationships by utilizing one nuclear DNA (nrITS) and seven plastid genes (rbcL, trnS, trnG, matK, trnL, psbA, and atpI) from 70 species (varieties) in Cymbidium. We also examined the occurrence of phylogenetic conflict between nuclear (nrITS) and plastid loci and investigated how phylogenetic conflict bears on taxonomic classification within the genus. We found that phylogenetic conflict and low support values may be explained by hybridization and a lack of informative characteristics. Our results do not support previous classification of the subgenera and sections within Cymbidium. Discordance between gene trees and network analysis indicate that reticulate evolution occurred in the genus Cymbidium. Overall, our study indicates that Cymbidium has undergone a complex evolution.

Ultra-strong mechanical property and force-driven malleability of water-poor hydrogels.

Hydrogels are known as soft and wet materials. Development of metal-like hydrogels with super strong and malleable properties is highly desirable as it allows for broader application and reprocessability. Here we report a dual nanocomposite hydrogel with peculiar mechanical properties in water-poor region. The gel with water content of 35% exhibits excellent recovery and fatigue resistance with elongation at break exceeding 800%, while the gel with 15 wt% of water content shows an ultra-high compressive strength and modulus of more than 1 GPa. The dual nanocomposite structure and bound water endowed the gel with high strength. Besides, the gel modulus can be easily switched by temperature change in a reversible way due to hybrid crosslinking network of the hydrogel in which physical network breaks and reforms rapidly while chemical network remains the gel state. So the gel shows a force-driven softening behavior and can be molded into different shapes due to reversible thermo-induced modulus decline. The softening behavior is also beneficial for the self-healing of the gel. The peculiar mechanical properties make the hydrogel a potential candidate for a new generation of advanced engineering materials.

The complete chloroplast genome of Cymbidium erythraeum (Orchidaceae).

Cymbidium erythraeum Lindl. is an endangered species of Orchidaceae and distributed in China and Bhutan, India, Myanmar, Nepal, and Vietnam. Here, we report the complete chloroplast (cp) genome sequence and the cp genome features of C. erythraeum. The complete chloroplast (cp) genome sequence of C. erythraeum is 156,327 bp in length and including one large single-copy region (LSC, 85,404 bp), one small single-copy region (SSC, 20,021 bp), and two inverted repeat regions (IRs, 25,426 bp). The cp genome encoded 136 genes, of which 107 were unique genes (80 protein-coding genes, 23 tRNAs, and four rRNAs). The phylogenetic relationships show that C. erythraeum is closely related to other species in the genus Cymbidium and is sister with C. tracyanum.

Complete chloroplast genome of Dendrobium thyrsiflorum (Orchidaceae).

Dendrobium thyrsiflorum H. G. Reichenbach ex André is an endemic herb with ornamental and medicinal orchid value distributed in Southeast of Yunnan of China. Here, we report and characterize the complete chloroplast (cp) genome sequence of D. thyrsiflorum in order to provide genomic resources helpful for its identification, conservation and utilization. The complete cp genome of D. thyrsiflorum is 160,123 bp, including one large single-copy region (LSC, 88,001), one small single-copy region (SSC, 21,142), and two inverted repeat regions (IRs, 25,490). The cp genome contains 143 genes, consisting of 110 unique genes (80 protein-coding genes, 26 tRNAs, and 4 rRNAS). The phlyogenetic relationships show that D. thyrsiflorum is closely related to other species of Dendrobium.

The complete chloroplast genome of Pholidota imbricata (Orchidaceae).

Pholidota imbricata belongs to tribe Coelogninae in Orchidaceae distributed in Sichuan, Xizang, and Yunnan. Here, we report the first complete chloroplast (cp) genome and the cp genome features of P. imbricata. The complete cp genome sequence of P. imbricata is 159,292 bp in length and presented a typical quadripartite structure including one large single-copy region (LSC, 87,515 bp), one small single-copy region (SSC, 20,999 bp), and two inverted repeat regions (IRs, 25,389 bp each). The cp genome encoded 141 genes, of which 108 were unique genes (80 protein-coding genes, 24 tRNAs, and 4 rRNAs). The phylogenetic relationships show that P. imbricata is sister to the species of the genus Pleione in tribe Coelogninae.

Flame-retardant and smoke-suppressant flexible polyurethane foams based on reactive phosphorus-containing polyol and expandable graphite.

In this manuscript, flame-retardant and smoke-suppressant flexible polyurethane foams (FPUFs) were designed and synthesized based on novel liquid phosphorus-containing polyol named as PDEO and expandable graphite (EG). The reactive PDEO can be chemically added into the chain of FPUF, while expandable graphite was blended into the matrix of foam through foaming process. Benefitting from the incorporation of reactive PDEO with a long chain, the resultant FPUF containing EG exhibited considerable mechanical properties. More importantly, the synergistic effect of PDEO and EG can endow FPUF with great flame retardancy, anti-driping performances. Furthermore, the resultant FPUF/EG/PDEO foams exhibit considerable smoke suppression performances. The vertical burning test revealed that the FPUF containing 5 php PDEO and 10 php EG extinguished quickly without dripping and kept the original shape after removing the igniter. The cone calorimeter results demonstrated that the synergistic effect of PDEO and EG can effectively reduce the heat release rate (HRR) and total release rate (THR) of the composite foam. Remarkably, the smoke production release (SPR), total smoke production (TSP), light transmission and specific optical density results indicated significantly smoke-suppressant properties of the composite foam. The mechanism analysis confirmed that the synergistic effect of gas-condensed bi-phase action from PDEO and EG contributed the great flame retardation of the composite foam. This novel FPUF provides a promising strategy for producing the polymer foam with flame retardation, smoke suppression and anti-dripping performances.

Epoxidized soybean oil cured with tannic acid for fully bio-based epoxy resin.

The construction of fully bio-based epoxy resins (EP) has been of particular interest in both academia and industrial circles for years; among these, epoxidized soybean oil (ESO) derived thermosets have received the most attention, but they usually exhibit poor performance due to their flexible fatty chains. Herein, tannic acid (TA), with its great degree of functionality and massive aromatic structures, was chosen as the multi-phenol curing agent for ESO to prepare fully bio-based EP thermosets with a high relaxation temperature and satisfactory mechanical properties. As a natural 2-substituted imidazole-containing substance, histidine (H) was used as the curing accelerator under moderate curing conditions (120-180 °C). This EP system showed high curing activity and a good curing degree while operating. The cured thermosets were found to be thermally stable (T 5% > 270 °C) and displayed a high relaxation temperature (77 °C) with a tensile strength of 23 MPa. Preliminary adhesion tests showed that the cured product exhibited a high lap-shear strength of about 19 MPa in adhesion failure mode. Taking these advantages into account, this kind of fully bio-based EP could introduce more chances for versatile applications, such as being used in structural materials and construction adhesives.

A new molecular phylogeny and a new genus, Pendulorchis, of the Aerides-Vanda alliance (Orchidaceae: Epidendroideae).

BACKGROUND: The Aerides-Vanda alliance is a complex group in the subtribe Aeridinae (subfamily Epidendroideae, Orchidaceae). Some phylogenetic systems of this alliance have been previously proposed based on molecular and morphological analyses. However, several taxonomic problems within this alliance as well as between it and its allies remain unsolved. METHODOLOGY/PRINCIPAL FINDINGS: We utilized ITS and five plastid DNA regions in this phylogenetic analysis. Consensus trees strongly indicate that the Aerides-Vanda alliance is monophyletic, and the 14 genera of this alliance can be grouped into the following clades with 14 subclades: 1. Aerides, comprising two subclades: Rhynchostylis and Aerides; 2. Ascocentropsis; 3. Papilionanthe; 4. Vanda, comprising five subclades: Neofinetia, Christensonia, Seidenfadenia, Ascocentrum, and Vanda-Trudelia, in which Vanda and Trudelia form a subclade; 5. Tsiorchis, comprising three subclades: Chenorchis, Tsiorchis, and two species of Ascocentrum; 6. Paraholcoglossum; and 7. Holcoglossum. Among the 14 genera, only Ascocentrum is triphyletic: two species of the Ascocentrum subclade, an independent subclade Ascocentrum subclade in the Tsiorchis clade; the Ascocentrum subclade in the Vanda clade; and one species in the Holcoglossum clade. The Vanda and Trudelia species belong to the same subclade. The molecular conclusion is consistent with their morphological characteristics. CONCLUSIONS: We elucidate the relationship among the 14 genera of the Aerides-Vanda alliance. Our phylogenetic results reveal that the Aerides-Vanda alliance is monophyletic, but it can be divided into 14 genera. The data prove that Ascocentrum is triphyletic. Plants with elongate-terete leaves and small flowers should be treated as a new genus, Pendulorchis. Saccolabium himalaicum (Ascocentrum himalaicum) should be transferred to Pendulorchis. Ascocentrum pumilum, endemic to Taiwan, should be transferred to Holcoglossum. A new combination, Holcoglossum pumilum, was also established. Trudelia should not be recognized as an independent genus. Two new species, Pendulorchis gaoligongensis and Holcoglossum singchianum, were described as well.

Adding perches for cross-pollination ensures the reproduction of a self-incompatible orchid.

BACKGROUND: Outcrossing is known to carry genetic advantages in comparison with inbreeding. In many cases, flowering plants develop a self-incompatibility mechanism, along with a floral component adaptation mechanism, to avoid self-pollination and to promote outbreeding. Orchids commonly have a lip in their flower that functions as the a visiting plate for insect pollinators. Aside from the lip, however, many species (including Coelogyne rigida) have sheaths around the axis of inflorescence. The function of these sheaths remains unknown, and has long been a puzzle to researchers. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the function of these sheaths in relation to the lip and the pollinators, as well as their role in the modes of pollination and reproduction of Coelogyne rigida in 30 flowering populations of orchids in the limestone area of Southeast Yunnan, China. We found that self-incompatible C. rigida developed specialized bird perches around the basal axis of inflorescence to attract sunbirds and to complement their behavioral tendency to change foraging locations frequently. This self-incompatibility mechanism operates separately from the floral component adaptation mechanism. This mechanism thus prevents bees from repeatedly visiting the floral lip of the same plant which, in turn, results in autogamy. In this way, instead of preventing autogamy, C. rigida responds to these negative effects through a highly efficient cross-pollination method that successfully transfers pollen to different plants. CONCLUSIONS: The proposed method ensures reproductive success, while offsetting the infertile self-pollination by insects, thereby reducing mating costs and addressing the lack of cross-pollination. The adaptation provides a novel and striking example of structural adaptation that promotes cross-pollination in angiosperms.