Two-step thermotropic phase transition and dielectric relaxation in 1D supramolecular lead iodide perovskite [NH4@18-crown ether]PbI3.

The supramolecular lead iodide perovskite crystals, {[NH4(18-crown-6)]PbI3}∞ (1), (18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane), was successfully achieved by a facile solvent evaporation strategy using a DMF solution containing equal molar quantities of PbI2, NH4I and 18-crown-6. The supramolecular perovskite was characterized by microanalysis for C, H and N elements, thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and single crystal X-ray diffraction techniques. DSC measurements demonstrated that 1 experiences a two-step thermotropic phase transition around 333 K and 383 K, respectively. The phase transition is relevant to the disorder-order transformation of the 18-crown-6 molecule at ∼333 K, while both breaking-symmetry and ordered-disordered transformation of the 18-crown-6 molecule occurred at ∼383 K. In addition, the sharp change of the PbI6 coordination octahedron distortion degree plays a synergistic role in the two-step phase transition. The dielectric relaxation occurs above 243 K in 1 and is mainly attributed to the displacement of the NH4+ ions relative to the ring of the 18-crown-6 molecule and {PbI3}∞ chain induced by an AC electrical field.

Genomic insights into the genotype-environment mismatch and conservation units of a Qinghai-Tibet Plateau endemic cypress under climate change.

Habitat loss induced by climate warming is a major threat to biodiversity, particularly to threatened species. Understanding the genetic diversity and distributional responses to climate change of threatened species is critical to facilitate their conservation and management. Cupressus gigantea, a rare conifer found in the eastern Qinghai-Tibet Plateau (QTP) at 3000-3600 m.a.s.l., is famous for its largest specimen, the King Cypress, which is >55 m tall. Here, we obtained transcriptome data from 96 samples of 10 populations covering its whole distribution and used these data to characterize genetic diversity, identify conservation units, and elucidate genomic vulnerability to future climate change. After filtering, we identified 145,336, 26,103, and 2833 single nucleotide polymorphisms in the whole, putatively neutral, and putatively adaptive datasets, respectively. Based on the whole and putatively neutral datasets, we found that populations from the Yalu Tsangpo River (YTR) and Nyang River (NR) catchments could be defined as separate management units (MUs), due to distinct genetic clusters and demographic histories. Results of gradient forest models suggest that all populations of C. gigantea may be at risk due to the high expected rate of climate change, and the NR MU had a higher risk than the YTR MU. This study deepens our understanding of the complex evolutionary history and population structure of threatened tree species in extreme environments, such as dry river valleys above 3000 m.a.s.l. in the QTP, and provides insights into their susceptibility to global climate change and potential for adaptive responses.

Negatively Charged MOF-Based Composite Anion Exchange Membrane with High Cation Selectivity and Permeability.

Every metal and metallurgical industry is associated with the generation of wastewater, influencing the living and non-living environment, which is alarming to environmentalists. The strict regulations about the dismissal of acid and metal into the environment and the increasing emphasis on the recycling/reuse of these effluents after proper remedy have focused the research community's curiosity in developing distinctive approaches for the recovery of acid and metals from industrial wastewaters. This study reports the synthesis of UiO-66-(COOH)2 using dual ligand in water as a green solvent. Then, the prepared MOF nanoparticles were introduced into the DMAM quaternized QPPO matrix through a straightforward blending approach. Four defect-free UiO-66-(COOH)2/QPPO MMMs were prepared with four different MOF structures. The BET characterization of UiO-66-(COOH)2 nanoparticles with a highly crystalline structure and sub-nanometer pore size (~7 Å) was confirmed by XRD. Because of the introduction of MOF nanoparticles with an electrostatic interaction and pore size screening effect, a separation coefficient (SHCl/FeCl2) of 565 and UHCl of 0.0089 m·h-1 for U-C(60)/QPPO were perceived when the loading dosage of the MOF content was 10 wt%. The obtained results showed that the prepared defect-free MOF membrane has broad prospects in acid recovery applications.

Evolutionary history of two rare endemic conifer species from the eastern Qinghai-Tibet Plateau.

BACKGROUND AND AIMS: Understanding the population genetics and evolutionary history of endangered species is urgently needed in an era of accelerated biodiversity loss. This knowledge is most important for regions with high endemism that are ecologically vulnerable, such as the Qinghai-Tibet Plateau (QTP). METHODS: The genetic variation of 84 juniper trees from six populations of Juniperus microsperma and one population of Juniperus erectopatens, two narrow-endemic junipers from the QTP that are sister to each other, was surveyed using RNA-sequencing data. Coalescent-based analyses were used to test speciation, migration and demographic scenarios. Furthermore, positively selected and climate-associated genes were identified, and the genetic load was assessed for both species. KEY RESULTS: Analyses of 149 052 single nucleotide polymorphisms showed that the two species are well differentiated and monophyletic. They diverged around the late Pliocene, but interspecific gene flow continued until the Last Glacial Maximum. Demographic reconstruction by Stairway Plot detected two severe bottlenecks for J. microsperma but only one for J. erectopatens. The identified positively selected genes and climate-associated genes revealed habitat adaptation of the two species. Furthermore, although J. microsperma had a much wider geographical distribution than J. erectopatens, the former possesses lower genetic diversity and a higher genetic load than the latter. CONCLUSIONS: This study sheds light on the evolution of two endemic juniper species from the QTP and their responses to Quaternary climate fluctuations. Our findings emphasize the importance of speciation and demographic history reconstructions in understanding the current distribution pattern and genetic diversity of threatened species in mountainous regions.

Regulation of Polyvinyl Alcohol/Sulfonated Nano-TiO2 Hybrid Membranes Interface Promotes Diffusion Dialysis.

It is important to emphasize that the adjustment of an organic-inorganic interfacial chemical environment plays an important role during the separation performance of composite materials. In this paper, a series of hybrid membranes were prepared by blending polyvinyl alcohol (PVA) solution and sulfonated nano-TiO2 (SNT) suspension. The effects of different interfacial chemical surroundings on ions transfer were explored by regulating the dosage content of SNT. The as-prepared membranes exhibited high thermal and mechanical stability, with initial decomposition temperatures of 220-253 °C, tensile strengths of 31.5-53.4 MPa, and elongations at break of 74.5-146.0%. The membranes possessed moderate water uptake (WR) values of 90.9-101.7% and acceptable alkali resistances (swelling degrees were 187.2-206.5% and weight losses were 10.0-20.8%). The as-prepared membranes were used for the alkali recovery of a NaOH/Na2WO4 system via the diffusion dialysis process successfully. The results showed that the dialysis coefficients of OH- (UOH) were in a range of 0.013-0.022 m/h, and separate factors (S) were in an acceptable range of 22-33. Sulfonic groups in the interfacial regions and -OH in the PVA main chains were both deemed to play corporate roles during the transport of Na+ and OH-.

Preparation of Polyvinyl Alcohol (PVA)-Based Composite Membranes Using Carboxyl-Type Boronic Acid Copolymers for Alkaline Diffusion Dialysis.

Carboxyl-type boronic acid copolymers (CBACs) were synthesized by a radical polymerization method and used for the preparation of polyvinyl alcohol (PVA)-based composite membranes via a solution mixture method. The as-prepared composite membranes exhibited a water uptake (WR) of 122.6-150.0%, an ion exchange capacity (IEC) of 0.0147-0.0518 mmol g-1, and excellent mechanical (elongation at break (Eb) of 103.8-148.4%, tensile strength (TS) of 38.7-58.6 MPa) and thermal stability. The alkali resistances of the as-prepared membranes were tested by immersing the samples into 2 mol L-1 NaOH solutions at 25 °C for 60 h, and the results were encouraging: the mass loss and swelling degree of the as-prepared membranes were in the ranges of 1.9-5.9% and 222.6-241.9%, respectively. The separation performances of the as-prepared membranes were evaluated by the diffusion dialysis (DD) process with an NaOH/Na2WO4 mixture at room temperature. The results demonstrated that the dialysis coefficients of hydroxide (UOH) were in the range of 0.0147-0.0347 m h-1, and the separation factors (S) were in the range of 29.5-62.6. The introduced carboxyl groups from CBACs and the -OH groups from PVA were both deemed to play significant roles in the promotion of ion transport: the -COO- groups formed negatively charged transport channels for Na+ by electrostatic attraction, and the -OH groups promoted the transport of OH- via hydrogen bonding.

Interface cisplatin-crosslinked doxorubicin-loaded triblock copolymer micelles for synergistic cancer therapy.

Combination chemotherapy is an effective way to improve the therapeutic efficiency in anticancer treatment. Herein, we synthesized a novel amphiphilic triblock copolymer via a two-step ring-opening polymerization (ROP) followed by post-modification. Doxorubicin (DOX) was encapsulated into the copolymeric micelles through hydrophobic interactions, cisplatin (CDDP) was employed to in situ crosslink the interface of DOX-loaded micelles through Pt-carboxyl coordination interaction. The CDDP-mediated crosslinking improved the stability of the micelles and also reduced the release of DOX at physiological pH. After being taken up into the endosome/lysosome, the low environmental pH weakened the Pt-carboxyl coordination interactions, resulting in the destruction of the micelles and the release of CDDP and DOX. Moreover, these micelles loaded with dual drugs enabled a synergistic anticancer effect, showing promise as a potential drug delivery platform for cancer therapy.

Allopatric divergence and hybridization within Cupressus chengiana (Cupressaceae), a threatened conifer in the northern Hengduan Mountains of western China.

Having a comprehensive understanding of population structure, genetic differentiation and demographic history is important for the conservation and management of threatened species. High-throughput sequencing (HTS) provides exciting opportunities to address a wide range of factors for conservation genetics. Here, we generated HTS data and identified 266,884 high-quality single nucleotide polymorphisms from 82 individuals of Cupressus chengiana, to assess population genomics across the species' full range, comprising the Daduhe River (DDH), Minjiang River (MJR) and Bailongjiang River (BLJ) catchments in western China. admixture, principal components analysis and phylogenetic analyses indicated that each region contains a distinct lineage, with high levels of differentiation between them (DDH, MJR and BLJ lineages). MJR was newly distinguished compared to previous surveys, and evidence including coalescent simulations supported a hybrid origin of MJR during the Quaternary. Each of these three lineages should be recognized as an evolutionarily significant unit (ESU), due to isolation, differing genetic adaptations and different demographic history. Currently, each ESU faces distinct threats, and will require different conservation strategies. Our work shows that population genomic approaches using HTS can reconstruct the complex evolutionary history of threatened species in mountainous regions, and hence inform conservation efforts, and contribute to the understanding of high biodiversity in mountains.

Interface crosslinked mPEG-b-PAGE-b-PCL triblock copolymer micelles with high stability for anticancer drug delivery.

The stability of polymeric micelles is a key property for anticancer drug delivery. In this study, a novel amphiphilic triblock copolymer, methoxy poly(ethylene glycol)-b-poly(allyl glycidyl ether)-b-poly(ε-caprolactone) (mPEG-b-PAGE-b-PCL), with different hydrophobic lengths was designed and synthesized using the combination of two successive ring-opening polymerizations. The products were characterized using 1H NMR and gel permeation chromatography (GPC). The triblock copolymers could self-assemble into micelles to encapsulate doxorubicin (DOX). The diameter of the DOX-loaded micelles increased from 63 to 92 nm with increasing PCL block length in the copolymer composition. The interface of the mPEG-b-PAGE-b-PCL micelles was crosslinked by a thiol-ene reaction with 1,4-butanedithiol. The stability, drug release and in vitro cytotoxicity of the DOX-loaded micelles were studied. The results showed that the DOX-loaded micelles could be effectively endocytosed by cancer cells and have good antitumor efficacy. In addition, the crosslinked micelles (CLMs) had better tumor accumulation than the noncrosslinked micelles (NCLMs) after intravenous injection using the lipophilic dye DiR.

The complete chloroplast genome of Juniperus squamata (Cupressaceae), a shrubby conifer from Asian Mountains.

The complete chloroplast genome of Juniperus squamata, a shrubby conifer of ornamental value, is determined in this study. The complete chloroplast genome size is 127,792 bp in length. The genome contains 118 genes, including 82 protein-coding genes, 32 transfer RNA genes, and four ribosomal RNA genes (16S ribosomal RNA, 23S ribosomal RNA, 4.5S ribosomal RNA, and 5S ribosomal RNA). It does not contain inverted repeat (IR) sequence. The overall GC content of J. squamata cpDNA is 35.1%. The phylogenetic analysis suggests its close relationship with J. recurva and J. tibetica from Himalaya and the Qinghai-Tibet Plateau, respectively. The genome may contribute to evolutionary studies of conifers.

Y-shaped copolymers of poly(ethylene glycol)-poly(ε-caprolactone) with ketal bond as the branchpoint for drug delivery.

In this study, a Y-shaped amphiphilic block copolymer consisting of hydrophilic poly(ethylene glycol) (mPEG) and two poly(ε-caprolactone) (PCL) as the hydrophobic arms with a ketal linker was synthesized (mPEG-Ketal-(PCL)2). The structure of the copolymer with different compositions was characterized by 1H NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The amphiphilic property endows the copolymer with the ability to be self-assembled into micelles for encapsulating anticancer drug doxorubicin (DOX), and the effect of copolymer with different PCL length on drug loading properties were tested. The morphology, size, pH responsiveness, drug release profile and in vitro anticancer activity of the DOX loaded micelles were also studied. In vitro drug release studies showed that over 50% of the DOX was released at pH 5.0 in 24 h because of hydrolysis of ketal linker in the copolymers. The confocal laser microscopy and flow cytometry experiments showed that the DOX-loaded micelles could be effectively internalized by Hela cells, the ketal bond in the backbone was broken in acid endo/lysosomal compartments and triggered the fast release of DOX. The in vitro antitumor efficacy of the DOX loaded mPEG-Ketal-(PCL)2 micelles was better than that of non-pH sensitive ones. In vivo studies showed that the mPEG-Ketal-(PCL)2 micelles enhanced the DOX blood circulation time and had good tumor-targeting efficiency.

Composite Cationic Exchange Membranes Prepared from Polyvinyl Alcohol (PVA) and Boronic Acid Copolymers for Alkaline Diffusion Dialysis.

Boronic acid copolymers with a large number of functional groups were obtained via a free radical polymerization method. The corresponding composite membranes for alkaline diffusion dialysis (DD) were prepared by a crosslinking reaction between polyvinyl alcohol (PVA) and the as-obtained boronic acid copolymers. The composite membranes possessed water uptake (WR) of 122.1⁻194.4%, ion exchange capacities (IECs) of 0.79⁻1.17 mmol/g, as well as both good mechanical stability (tensile strength of 40.7⁻49.9 MPa and elongation at break of 52.1⁻121.1%) and thermal stability. The as-prepared membranes were stable in 2 M NaOH solution at 65 °C with a swelling degree and mass loss of as-prepared membranes in the range of 305⁻368% and 9.2⁻22%, respectively. A NaOH/Na2WO4 mixture was used to investigate the separation properties of as-prepared membranes via the DD process. Results indicated that the dialysis coefficients of OH- (UOH) were in the range of 0.0079⁻0.0150 m/h, while the separation factors (S) were in the range of 26.6⁻53.2. The functional groups from boronic acid copolymer and ⁻OH from PVA were demonstrated to promote the ion transport synergistically.

Preparation of the Yellow-Colored Aluminum Pigments with Double-Layer Structure Using a Crosslinked Copolymeric Dye.

Colorization for fabricating aluminum pigments has broad application prospects in recent years. In this study, yellow-colored aluminum pigments with the double-layer structure Al@SiO2@PFMV were prepared using a sol-gel method. A crosslinked copolymeric dye (PFMV) was firstly synthesized by radical polymerization using vinyl triethoxysilane (VTES) and a small molecular dye (FGMAC) as monomers. Then, colored aluminum pigments were prepared by hydrolysis and condensation of the copolymers on the surface of aluminum pigments. SEM, AFM, FTIR, and XPS were used to characterize the surface morphology and chemical structure of the colored aluminum pigments. It was found that the colored aluminum pigments have a heterogeneous and smooth surface layer. The anticorrosion results showed that the colored aluminum pigments had better chemical stability with significantly improving corrosion resistance compared to raw aluminum pigments and Al@SiO2 with the single-layer coating. Chromatism analysis indicated that the lightness of Al@SiO2@PFMV pigments decreased slightly and the color changed from silver-gray to yellow.

Click Chemistry Finds Its Way in Constructing an Ionic Highway in Anion-Exchange Membrane.

To find the way to construct an ionic highway in anion-exchange membranes (AEMs), a series of side-chain-type alkaline polymer electrolytes (APEs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) polymer backbones were synthesized via Cu(I)-catalyzed click chemistry. The resulting triazole groups and quaternary ammonium (QA) groups facilitate the formation of a continuous hydrogen bond network, which will lead to high hydroxide conductivity according to Grotthuss-type mechanism. Microphase separation induced by long alkyl side chains contributes at the same time to further improving the hydroxide conductivity of the resultant AEMs. Hydroxide conductivity as high as 52.8 mS/cm is obtained for membrane TA-14C-1.21 (IEC = 1.21 mmol/g) with the longest pendant chain at 30 °C, and the conductivity can be increased to 140 mS/cm when the temperature was increased to 80 °C. Moreover, the corresponding water uptake is only 8.6 wt % at 30 °C. In the meantime, the membrane properties can be tuned by precisely regulating the hydrophilic/hydrophobic ratio in the cationic head groups. Compared with AEMs containing triazole and quaternized trimethylammonium head groups, enhanced dimensional stability and mechanical properties are obtained by tuning side-chain chemistry. However, the alkaline stability of the membrane is not as stable as anticipated, probably because of the existence of the triazole ring. Further study will be focused on increasing the alkali stability of the membrane. We envisage that the side-chain-type APEs meditated by click chemistry bearing long hydrophobic side chains pendant to the cationic head groups hold promise as a novel AEMs material.