Moderate Surface Research Articles

COF-300 synthesis and colloidal stabilization with substituted benzoic acids.

Colloidal covalent organic framework (COF) synthesis enables morphological control of crystallite size and shape. Despite numerous examples of 2D COF colloids with various linkage chemistries, 3D imine-linked COF colloids are more challenging synthetic targets. Here we report a rapid (15 min-5 day) synthesis of hydrated COF-300 colloids ranging in length (251 nm-4.6 μm) with high crystallinity and moderate surface areas (150 m2 g-1). These materials are characterized by pair distribution function analysis, which is consistent with the known average structure for this material alongside different degrees of atomic disorder at different length scales. Additionally, we investigate a series of para-substituted benzoic acid catalysts, finding that 4-cyano and 4-fluoro substituted benzoic acids produce the largest COF-300 crystallites with lengths of 1-2 μm. In situ dynamic light scattering experiments are used to assess time to nucleation in conjunction with 1H NMR model compound studies to probe the impact of catalyst acidity on the imine condensation equilibrium. We observe cationically stabilized colloids with a zeta potential of up to +14.35 mV in benzonitrile as a result of the carboxylic acid catalyst protonating surface amine groups. We leverage these surface chemistry insights to synthesize small COF-300 colloids using sterically hindered diortho-substituted carboxylic acid catalysts. This fundamental study of COF-300 colloid synthesis and surface chemistry will provide new insights into the role of acid catalysts both as imine condensation catalysts and as colloid stabilizing agents.

Sub-50 nm core-shell nanoparticles with the pH-responsive squeezing release effect for targeting therapy of hepatocellular carcinoma.

The development of drug delivery systems with high drug loading capacity, low leakage at physiological pH, and rapid release at the lesion sites remains an ongoing challenge. In this work, core-shell poly(6-O-methacryloyl-D-galactose)@poly(tert-butyl methacrylate) (PMADGal@PtBMA) nanoparticles (NPs) of sub-50 nm are facilely synthesized by reversible addition-fragmentation chain transfer (RAFT) soap-free emulsion polymerization with the assistance of 12-crown-4. A hydrophilic poly(methacrylic acid) (PMAA) core can then be revealed after deprotection of the tert-butyl groups, which is negatively charged and can adsorb nearly 100% of incubated doxorubicin (DOX) from a solution at pH 7.4. The physical shrinkage of PMAA chains below pH 6.0 endows the core with the squeezing effect, therefore realizing rapid drug release. It is demonstrated that the DOX release rate of PMADGal@PMAA NPs at pH 5 was 4 times that at pH 7.4. Cellular uptake experiments confirm the high targeting ability of the galactose modified PMADGal shell to human hepatocellular carcinoma (HepG2) cells. The fluorescence intensity of DOX in HepG2 cells is 4.86 times that of HeLa cells after 3 h incubation. Moreover, 20% cross-linked NPs show the highest uptake efficiency by HepG2 cells due to their moderate surface charge, size and hardness. In summary, both the core and the shell of PMADGal@PMAA NPs promise the rapid site-specific release of DOX in HepG2 cells. This work provides a facile and an effective strategy to synthesize core-shell NPs for hepatocellular carcinoma targeting therapy.

Spiers Memorial Lecture: Towards understanding of iontronic systems: electroosmotic flow of monovalent and divalent electrolyte through charged cylindrical nanopores.

In many practical applications, ions are the primary charge carrier and must move through either semipermeable membranes or through pores, which mimic ion channels in biological systems. In analogy to electronic devices, the "iontronic" ones use electric fields to induce the charge motion. However, unlike the electrons that move through a conductor, motion of ions is usually associated with simultaneous solvent flow. A study of electroosmotic flow through narrow pores is an outstanding challenge that lies at the interface of non-equilibrium statistical mechanics and fluid dynamics. In this paper, we will review recent works that use dissipative particle dynamics simulations to tackle this difficult problem. We will also present a classical density functional theory (DFT) based on the hypernetted-chain approximation (HNC), which allows us to calculate the velocity of electroosmotic flows inside nanopores containing 1 : 1 or 2 : 1 electrolyte solution. The theoretical results will be compared with simulations. In simulations, the electrostatic interactions are treated using the recently introduced pseudo-1D Ewald summation method. The zeta potentials calculated from the location of the shear plane of a pure solvent are found to agree reasonably well with the Smoluchowski equation. However, the quantitative structure of the fluid velocity profiles deviates significantly from the predictions of the Smoluchowski equation in the case of charged pores with 2 : 1 electrolyte. For low to moderate surface charge densities, the DFT allows us to accurately calculate the electrostatic potential profiles and the zeta potentials inside the nanopores. For pores with 1 : 1 electrolyte, the agreement between theory and simulation is particularly good for large ions, for which steric effects dominate over the ionic electrostatic correlations. The electroosmotic flow is found to depend very strongly on the ionic radii. In the case of pores containing 2 : 1 electrolyte, we observe a reentrant transition in which the electroosmotic flow first reverses and then returns to normal as the surface change density of the pore is increased.

Cobalt diselenide nanotetrapod: An efficient electrocatalyst for hydrogen evolution reaction

The science and technology is going through an era where a simple and cost effective synthesis of an earth abundant and efficient electrocatalyst for hydrogen evolution reaction (HER) can provide a key to grand success of hydrogen fuel in practical application. Here, elemental Se mixed CoSe2 nanoparticles that have been synthesized by a simple two-step hydrothermal process own tetrapod-like structures. After important characterizations, CoSe2 nanotetrapod has been utilized as a cathode in the electrochemical HER process. It exhibits low onset potential of − 46 mV and requires almost − 112 mV and − 156 mV to draw current density of 10 and 100 mA/cm2, respectively with Tafel slope of 36 mV/dec. It also pursues low charge transfer resistance with moderate active surface area. The highly hydrophilic CoSe2 nanotetrapod persevere long term stability in acidic medium. Moreover, the high electron density obtained from Mott-Schottky, nanotetrapods with active sites, presence of metallic and conducting Se with electrochemically active CoSe2 and their favorable crystal facets have influenced the HER activity. Thus, the pristine binary CoSe2 can alone beat any previously reported electrochemical catalysts without developing any composites/hybrids or complex compounds.

How changes to the substrate’s physical characteristics can influence the deposition of touch and salivary deposits

An in-depth study into the physical substrate characteristics such as substrate surface roughness, topography, and physicochemical characteristics like wettability and surface free energy (SFE) was conducted to investigate the impact on the deposition and adherence of touch and salivary deposits on aluminium and polypropylene. A robust protocol was established to generate a set of substrates with a controlled linear surface roughness range (0.5–3.5 µm) in order to identify the impact of surface roughness on DNA transfer, persistence, prevalence, and recovery (DNA-TPPR). The polypropylene substrate was shown to produce fibres when artificially roughened, becoming more prominent at a higher surface roughness range, and has shown to have a direct impact on the distribution of salivary and touch deposits. At the low to moderate surface roughness range 0.5–2.0 µm, salivary and touch deposits have generally shown to follow the topographical features of the substrate they were deposited on, before a plateau of the surface roughness measure on the deposit was observed, indicating that a saturation point was reached and the grooves in the substrate were beginning to fill. Touch deposits have shown to maintain a consistent deposition height pre-surface roughness threshold, irrespective of substrate surface roughness while the deposition height of salivary deposits was heavily influenced by substrate surface roughness and topography. The substrate SFE, wettability, hydrophobicity, and the surface tension of the deposit was shown to drive the adhesion properties of the saliva and touch deposits on the respective substrates, and it was observed that this may be of importance for the improvement of the current DNA-TPPR understanding, DNA sampling protocols, and DNA transfer considerations within casework.

Fabrication of High‐Quality Thin Single‐Crystal Diamond Membranes with Low Surface Roughness

Certain aspects before and during the fabrication of single‐crystal diamond (SCD) membranes are highlighted, which are decisive to obtain high‐quality membranes with low surface roughness values around 0.2 nm on a small area scale. In addition to the requirements for the starting material, including a high planarity and a moderate surface roughness, the importance of cleaning processes to minimize particles and impurities before and during the structuring is emphasized. With the help of a planarization procedure, consisting of a combination of different Ar/Cl2 recipes with low etch rates, surface defects like grooves due to polishing are minimized and smooth surfaces are acquired. Severe micro‐masking can be prevented by the application of a cyclic Ar/Cl2 + O2 recipe, allowing finally the fabrication of defect‐minimized and planarized SCD membranes in the thickness range between a few microns and a few hundred nanometers. The high quality of the structured SCD membranes is evidenced with a morphological as well as optical characterization via fiber‐based microcavity measurements.

Conversion of MoS2 to ternary alloyed MoS2−xSex for resistive NO2 sensors

The inert basal planes and strong quantum confinement of 2D materials usually lead to the reduction of carrier transport efficiency and device performance. In this work, a ternary alloyed MoS2-xSex nanocomposites has been prepared by converting few-layered MoS2 nanomaterials through a selenization process to boost the gas sensing performance of gas sensors at room temperature. The selenization process makes the MoS2-xSex nanocomposites generate weak interlayer coupling effect, rich surface defects (states), moderate surface strains, local built-in electric field, and can effectively eliminate oxide impurities in MoS2. Moreover, the band gap of the samples can be tuned from 1.74 eV for MoS2 nanomaterials to 1.49 eV for MoS2−xSex nanocomposites. Owing to the modified surface and electronic structures, the MoS2−xSex nanocomposites exhibit excellent NO2 sensing performance at room temperature in terms of response, repeatability, selectivity, and detection limit. The responses of the best MoS2−xSex nanocomposites are about 2–3 times that of the MoS2 nanomaterials, and its theoretical detection limit reaches 4.0 ppb. This study reveals that ternary alloyed TMDs have better development potential than their binary TMD counterparts in the field of gas sensors.

PENGARUH VARIASI PEMAKAIAN CAIRAN PENDINGIN (COOLANT) TERHADAP KEKASARAN PERMUKAAN BESI AS PUTIH ST 41 HASIL PEMBUBUTAN SILINDRIS ENGSEL

Coolant has special uses in the lathe machining process. In addition to extending tool life, coolant in some cases can reduce force and smooth the surface of the manufactured product. This study aims to determine the effect of differences in the use of coolant on the surface roughness of the hinge cylindrical turning (hinge) of ST 41 iron material. The choice of this material is because it is often used in machining tools and the price is economical. This type of research is experimental research conducted in a laboratory. This study uses quantitative methods. In the multilevel straight turning process as many as 3 hinge workpieces using 3 types of coolant (coolant). Hinge workpiece A uses water cooling without a mixture, hinge workpiece B uses water cooler with a mixture of coolant (coolant) and hinge workpiece C uses lubricant coolant. The turning of the three hinge workpieces is done by cylindrical turning. The results showed that the use of the lowest mean surface roughness cooling type was water cooler with a mixture of coolant (1,254 mm), the highest type of surface roughness average value was oil cooler (1,850 mm). While the average value of moderate surface roughness is the type of coolant (1,489 mm).

Adsorption of Pb(II) from Aqueous Solution Using Dendritic Fibrous Type SBA-15 (DFSBA-15)

The presence of heavy metals in the environment is undeniably harmful and toxic to living things, where the presence of Pb(II) inside human foods and drinks results in various diseases. The use of adsorption as a method of wastewater treatment is widespread, and effective adsorption performance depends on appropriate adsorbent selection. In this research, dendritic fibrous type SBA-15 (DFSBA-15) was prepared and used for lead (Pb(II)) adsorption. The physicochemical properties of the DFSBA-15 were characterized using TEM, BET, and FTIR. The characterization analyses confirmed the formation of fibrous morphology, moderate surface area, and bulk -OH. Several factors, including contact time (min), adsorbent dosage (g/L), pH, and initial concentration (mg/L), were examined for Pb(II) adsorption. The best adsorption performance (89.88%) was attained at 180 min, 1 g/L of adsorbent dosage, pH 5, and 100 mg/L of Pb(II) initial concentration. Pseudo-second-order reaction type and Langmuir isotherm provided good fits to the experimental data, with R2 ≥ 0.9943 and R2 = 0.9982, respectively. In short, the DFSBA-15 exhibits great potential for excellent Pb(II) removal.

Evaluation of remotely sensed global evapotranspiration data from inland river basins

AbstractRemotely sensed (RS) evapotranspiration (ET) data sets have been widely evaluated and applied at regional scale. However, the research is relatively insufficient on inland basins. RS global ET data sets were evaluated in 19 major inland basins around the world in this study. Monthly ET was estimated by using water balance (ET_WB), as well as multi‐source precipitation and total water storage anomaly data sets from each basin. The main attributes of the ET changes were identified in each basin. The accuracy of 10 ET products was evaluated by monthly ET_WB series over the entire study region and at the basin scales. Results showed that precipitation changes were the main cause of ET changes in most basins (i.e., 11/19). The impacts of human activities, mainly because of increased irrigation diversion, dominated the ET changes in the five basins located in the western and northern regions of the Eurasian inland basin. Accurate estimated ET series in inland basins with a regular unimodal or U distribution of mean monthly ET were also obtained; this was not the case for basins with irregular seasonal ET variations. In general, ET products exhibited accurate monthly ET estimates in most inland basins, but their accuracy was reduced at the Helmand River, Iranian inland rivers, Qaidam, and Turpan Basins. All products tended to underestimate ET, except for the Penman–Monteith–Leuning product. Overall, the global land surface satellite and global land evaporation Amsterdam model products performed the best in inland basins, while the moderate resolution imaging spectroradiometer (MODIS; MOD16A2) and surface energy balance system (SEBS) products performed relatively poorly. In addition, all products except SEBS and MOD16A2 could capture the spatial ET distribution in inland basins, and the spatial correlation coefficient ranged between 0.83 and 0.93. In general, an ensemble of optimized ET products could improve the accuracy of simulated monthly ET and reduce the uncertainty of the simulated series over the entire study region and at the basin scales.

Small-Molecule Electron Transport Layer with Siloxane-Functionalized Side Chains for Nonfullerene Organic Solar Cells.

Active layer materials with silicone side chains have been broadly reported to have excellent long-term stability in harsh environments. However, the application of conjugated materials with silicone side chains in electron transport layers (ETLs) has rarely been reported. In this research, we synthesized for the first time a siloxane-modified perylene-diimide derivative (PDI-OSi) consisting of a side-chain substituent of siloxane and a conjugated group of perylene-diimide (PDI). The inserted siloxane functional groups not only can strengthen the light transmittance of PDI-OSi but also can remarkably expand its solubility and improve the film-forming ability and air stability of the material. Second, introducing siloxane-containing side chains can dramatically lower the work function and interfacial barrier of the electrode, thereby achieving a favorable ohmic contact. In addition, the moderate surface energy of siloxane functional groups makes PDI-OSi hydrophobic, which is conducive to forming excellent miscibility with hydrophobic active layers to promote charge transfer. When PDI-OSi is used as an ETL in organic solar cells (OSCs), operative exciton dissociation and more favorable surface morphology enable OSCs to realize a power conversion efficiency (PCE) of 13.99%. These results indicate that side-chain engineering with siloxane pendants is a facile strategy for constructing efficient OSCs.

Ultrahigh level heteroatoms doped carbon nanosheets as cathode materials for Zn-ion hybrid capacitor: The indispensable roles of B containing functional groups

Heavily heteroatoms doped carbons are highly attractive for electrochemical energy storage and electrocatalysis applications. We report herein a versatile coordination chemistry strategy for the producing of B, N co-doped carbon nanosheets (BCN-Mg) with an ultrahigh doping level (15.26 % for N, 10.18 % for O, and 3.21 % for B) though pyrolysis of nitrogen-rich Mg-based complex in the presence of boric acid. In this protocol, hexamethylenetetramine, which acts as both carbon and nitrogen source, can easily complex with magnesium ion to form a nitrogen-rich Mg-based complex in aqueous solution due to the presence of plentiful amino groups with strong complexation capability. Benefiting from the ultrahigh doping level and moderate specific surface area of 428 m2 g−1, the as-obtained B, N co-doped carbon nanosheets display a high specific capacity of 130.7 mA h g−1 (at 0.1 A g−1), and good stability of 87.3 % after 10,000 cycles when serves as the cathode for aqueous Zn-ion hybrid capacitors. More importantly, change details of the N and B containing functional groups during the charge-discharge process have been fully evaluated by ex-situ X-ray photoelectron spectroscopy characterization technique and density functional theory calculations. This work not only offers a new way to develop B, N co-doped carbon nanosheets with an ultrahigh doping level but also shed some new insight on the roles of heteroatoms containing functional groups for electrochemical energy storage applications.

Lattice Boltzmann Simulation of Optimal Biphilic Surface Configuration to Enhance Boiling Heat Transfer

To study the processes of boiling on a smooth surface with contrast wettability, a hybrid model was developed based on Lattice Boltzmann method and heat transfer equation. The model makes it possible to describe the phenomena of natural convection, nucleate boiling, and transition to film boiling, and, thus, to study heat transfer and the development of crisis phenomena in a wide range of surface superheats and surface wetting characteristics. To find the optimal configuration of the biphilic surface, at the first stage a numerical simulation was carried out for a single lyophobic zone on a lyophilic surface. The dependences of the bubble departure frequency and the departure diameter of the bubble on the width of the lyophobic zone were obtained, and its optimal size was determined. At the next stage, the boiling process on an extended surface was studied in the presence of several lyophobic zones of a given size with different distances between them. It is shown that in the region of moderate surface superheat, the intensity of heat transfer on biphilic surfaces can be several times (more than 4) higher compared to surfaces with homogeneous wettability. Based on numerical calculations, an optimal configuration of the biphilic surface with the ratios of the lyophobic zones’ width of the order of 0.16 and the distance between the lyophobic zones in the range of 0.9–1.3 to the bubble departure diameter was found.

Analysis of turning chip morphology with various tool geometries using finite element modeling and simulation to optimize product sustainability

This paper focuses on finite element (FE) modeling using a Lagrangian approach with the ABAQUS/Explicit code to simulate the morphology of CSN 12050 carbon steel chips obtained using different tool rake and flank angles. The cutting operation was performed with a 3D model setup based on the cutting tool to determine the impact of the tool rake and flank angles on the total energy ( ETOTAL), the von Mises stresses, and the cutting force. In these simulations, using adaptive meshing for the tool, 0°, 5° and 10° rake angles, 0° and 6° flank angles, and 0.2-mm and 0.5-mm cut depths were considered as process parameters and the continuous chip morphology was predicted. The tool with 10° rake and 6° flank angles projected moderate machined surface integrity. The FE analysis tool predicted increased von Mises stresses and reduced cutting forces with the 10° rake and 6° flank angles. The maximum ETOTAL and cutting force were obtained for both cut depths when using a tool with 0° and 5° angles. Additionally, experimental results for the mechanical morphology properties of untreated, annealed and recrystallized CSN 12050 carbon steel chips showed that the predicted and experimental chip morphologies agreed well.

Studying the thermal resistance of superhydrophobic carbon soot coatings for heat transfer management in cryogenic facilities

Except in microelectronics, food industry and power generation, the accurate temperature control is a fundamental precondition for the sustainable development of cryobiology too, where the partial cryodamage of frozen/thawed biospecies is still unavoidable. Setting favorable cooling and warming rates during cryopreservation helps to mitigate the detrimental intracellular icing and recrystallization, which is accomplishable using superhydrophobic carbon soot, whose thermal resistance however, has not been examined so far. This research introduces the first attempts of quantifying the thermal behavior of three basic categories soot distinguished by morphology, porosity, chemical composition and film thickness. The gradual cooling of six pairs of non-wettable soot coatings reveals that the diffusive thermal transport in their bulk is accompanied by phonon scattering governed predominantly by the pore arrangements, particle size, chemical bonding and interlayer spacing in the material. In turn, the soot incorporating ∼ 50–120 nm-sized nanoparticles, mesopores, moderate surface oxidation and thickness exceeding 50 µm exhibits the greatest capacity to delay the bulk heat conduction, opposite to the empirically established solid-liquid interfacial heat transfer mechanisms of the soot. Thus, merging specific physicochemical features within a single coating, via controlled flame synthesis and alcohol-fluorocarbon functionalization, would facilitate the fabrication of custom cryovials alleviating the two-factor freezing injury.

Atomically dispersed SrOx species on exposed {2 2 2} facets of pyrochlore La2Zr2O7 nanocrystals for boosting low-temperature oxidative coupling of methane

The efficient catalysts of strontium oxide (SrOx) supported on exposed {222} facets of pyrochlore La2Zr2O7 nanocrystals (SrOx/LZO-Y) were elaborately synthesized by incipient wetness impregnation method. The introduction of atomically dispersed SrOx species on La2Zr2O7 surface can increase the amount of surface oxygen vacancies induced by Sr2+ substitution of La3+ cations, and the increasing of moderate surface alkaline sites are beneficial to enhance catalytic performance for oxidative coupling of methane (OCM). The SrOx/LZO-Y catalysts have super catalytic performance during low-temperature OCM reaction. SrOx/LZO-12 catalyst with the highest concentrations of O2– species exhibits the highest activity and the lowest apparent activation energy (84 kJ mol−1) during low-temperature OCM into C2H4 and C2H6 (C2) products, i.e., its CH4 conversion, selectivity and yield of C2 products at 600 °C are 30.5 %, 47.4 % and 14.5 %, respectively, and its ratio of C2H4/C2H6 products is 0.77. Based on the results of multiple experimental characterizations, the mechanism of SrOx/LZO-Y catalysts for OCM reaction is proposed: the surface alkaline active centers (O2–) induced by doping of Sr ions can promote the critical step of CH4 activation significantly during low-temperature OCM reaction. It is a new strategy to develop the low-temperature and high-activity catalysts for OCM in practical application.

Valorizing high-fraction bio-oil to prepare 3D interconnected porous carbon with efficient pore utilization for supercapacitor applications

Heavy-fraction bio-oil (HB) is an underused product of biomass pyrolysis due to its difficulty in direct use or efficient refinery, but it is a potential carbon precursor to prepare porous carbon for energy storage. The fluid HB with structural flexibility and miscibility is desirable to fabricate tailored carbon structure. In this work, we developed an in-situ activation method to convert HB into carbon-based electrode for supercapacitor applications. HB was pre-mixed with KOH activator in aqueous phase and then formed a solid composite, thus the inserted KOH could act as both activator and template agent for pore generation. The resultant porous carbon exhibits a 3D interconnected framework with micropore dominant structure. Benefiting from the structural features, the moderate surface area contributes a high capacitance indicating the excellent pore utilization efficiency, which is superior to most activated carbons and the commercial electrode material YP-50F. Furthermore, the porous carbon shows outstanding energy density, power density and cycling stability in both aqueous and organic electrolyte, indicating a promising application potential. The valorization of HB not only provides a cost-effective electrode material for energy storage, but also promotes the comprehensive utilization from biomass pyrolysis technology.

Assessing the Efficacy of Whole-Body Titanium Dental Implant Surface Modifications in Inducing Adhesion, Proliferation, and Osteogenesis in Human Adipose Tissue Stem Cells.

Although the influence of titanium implants' micro-surface properties on titanium discs has been extensively investigated, the research has not taken into consideration their whole-body effect, which may be considered possible using a combinatorial approach. Five titanium dental implants with a similar moderate roughness and different surface textures were thoroughly characterized. The cell adhesion and proliferation were assessed after adipose-tissue-derived stem cells (ADSCs) were seeded on whole-body implants. The implants' inductive properties were assessed by evaluating the osteoblastic gene expression. The surface micro-topography was analyzed, showing that hydroxyapatite (HA)-blasted and bland acid etching implants had the highest roughness and a lower number of surface particles. Cell adhesion was observed after 24 h on all the implants, with the highest score registered for the HA-blasted and bland acid etching implants. Cell proliferation was observed only on the laser-treated and double-acid-etched surfaces. The ADSCs expressed collagen type I, osteonectin, and alkaline phosphatase on all the implant surfaces, with high levels on the HA-treated surfaces, which also triggered osteocalcin expression on day seven. The findings of this study show that the morphology and treatment of whole titanium dental implants, primarily HA-treated and bland acid etching implants, impact the adherence and activity of ADSCs in osteogenic differentiation in the absence of specific osteo-inductive signals.

Bithiophene-based COFs for silver ions detection and removal

Covalent organic frameworks (COFs) are promising in the detection and removal of toxic heavy metal ions from water. However, achieving detection and removal functions requires systematic control of stability, porosity, pore environment, and luminescence properties, which remains a challenge for most COFs materials. Herein, we develop a bithiophene-based stable COF, TAPA-BTDC, with dual functions of simultaneous detection and removal of silver ions from aqueous solution through elaborate structural design and control of the pore environment. The obtained TAPA-BTDC has good thermal stability and chemical stability, possesses high crystallinity and moderate specific surface area (396.83 m2/g), and contains dense bithiophene-S chelating sites on the pore walls. These characteristics work together to give TAPA-BTDC the dual function of selective detection and effective removal of silver ions from aqueous solution. This dual function can be attributed to the π-complexation between bithiophene-S chelating sites and silver ions, as verified by X-ray photoelectron spectroscopy. The charge transfer between bithiophene-S and silver ions alters the weak fluorescence emission caused by the π−π layered structure, enabling TAPA-BTDC to selectively detect silver ions through fluorescence enhancement, and even trace amounts of Ag+ (2.4 × 10−4 mmol/L) can cause observable fluorescence emission. Meanwhile, these bithiophene-S scattered across the pore wall also provide a large number of accessible chelating sites for TAPA-BTDC, enabling it to effectively remove Ag+ with a maximum adsorption capacity up to 398.61 mg/g, and TAPA-BTDC can be easily regenerated five times without loss of performance. The results of this study reveal the exceptional potential of COFs with reasonably tailor-made structure in dealing with heavy metal ion contamination.

Can botanic gardens serve as refuges for taxonomic and functional diversity of Odonata? The case of the botanic garden of Castilla-La Mancha (Spain).

In a scenario with declining biodiversity and habitat loss, botanic gardens could serve as refuges for invertebrates, but the opportunities they offer for animal conservation are still poorly understood. Odonata is a good model group for conservation studies, because it includes threatened species and responses to habitat disturbance are well documented. In this study, we assessed the role of the botanic garden of Castilla-La Mancha in Spain as a refuge for members of Odonata by analysing their taxonomic and functional diversity. We explored if the small size of the botanic garden might constrain the taxonomic diversity of Odonata and if low habitat diversity might limit their functional diversity. We sampled adult Odonata from five water bodies along a gradient of human impact and characterized the Odonata communities based on 12 functional traits in Odonata. We used a species–area relationship to control for differences in the size of water bodies. Compared with natural lakes, the Odonata communities contained less species and their functional diversity was lower in the botanic garden ponds, where generalist species were basically hosted. Despite these limitations, the botanic garden ponds hosted the number of species expected for natural water bodies with the moderate surface area and functional diversity, thereby demonstrating that they are a valuable habitat for Odonata in an urban environment. Appropriate management involving the removal of exotic fish and habitat diversification, including creating lotic environments, would increase the taxonomic and functional diversity of Odonata in this urban system.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10201-022-00704-3.