Type Of Metal Research Articles

Theoretical and experimental study on the mechanical measurement of rock tensile fracture by ring radial compression

Conventional Brazilian disc splitting tests are hampered by stress concentration at the loading points, leading to test outcomes that do not truly represent the engineering failure strength of rocks. To enhance the accuracy of these tests, the specimen shape has progressed from the Brazilian disc to a circular ring. This study presents a theoretical analysis of the compression deformation process in circular rings, followed by platform-radial compression tests conducted on various types of rocks and metals, employing the digital speckle correlation method alongside an improved mechanical extensometer. The findings indicate that circular ring specimens failed under a combination of tensile and compressive stresses. The main crack originates along the loading direction on the inner wall of the ring and propagates outwards, resulting in the failure of the entire ring structure. While maximum tensile strain may serve as an indicator of rock failure, tensile stress alone should not be considered a definitive criterion for failure.

Metal implants in children

Background: Metal implants are increasingly used in children for trauma and deformity correction. This review outlines the current knowledge on the types of metals used and explores reasons for removal and the potential for long-term health issues of metal implants. Methods: The literature pertaining to these aspects was studied and summarised in this review. Results: Types of metals used have evolved as well as the development of children-specific implants. Improvements in deformity correction are measurable with likely improved outcomes and reduced health costs. Indications for metal implant removal following successful treatment remain ill-defined; however, the risks of removal are known with a minimum 6% complication rate. Health costs could be reduced by around 6% by judicious decisions to leave metal in place. Implant removal should only be encouraged in the presence of infection, mechanical failure or symptoms that are truly attributable to the implant. In the domain of spinal implants, there is evidence of significant metal ion release, most notably titanium which remains elevated to many times baseline levels beyond 2 years. The detection of titanium at low levels requires special techniques. The long-term health effects on patients and/or their offspring are not well defined, although well described in animal models. Conclusion: The risks of metal removal are significant. Clinicians need to be aware of potential health risks in the use of metal implants and the potential for covert toxicity effects in children especially with their long life ahead. There is a need for greater awareness of metal alloy composition and implant design to minimise risks. Level of evidence: Level V.

Microscopic mechanism of water-assisted diffusional phase transitions in inorganic metal halide perovskites.

The stability of perovskite materials is profoundly influenced by the presence of moisture in the surrounding environment. While it is well-established that water triggers and accelerates the black-yellow phase transition, leading to the degradation of the photovoltaic properties of perovskites, the underlying microscopic mechanism remains elusive. In this study, we employ classical molecular dynamics simulations to examine the role of water molecules in the yellow-black phase transition in a typical inorganic metal halide perovskite, CsPbI3. We have demonstrated, through interfacial energy calculations and classical nucleation theory, that the phase transition necessitates a crystal-amorphous-crystal two-step pathway rather than the conventional crystal-crystal mechanism. Simulations for CsPbI3 nanowires show that water molecules in the air can enter the amorphous interface between the black and yellow regions. The phase transition rate markedly increases with the influx of interfacial water molecules, which enhance ion diffusivity by reducing the diffusion barrier, thereby expediting the yellow-black phase transition in CsPbI3. We propose a general mechanism through which solvent molecules can greatly facilitate phase transitions that otherwise have prohibitively high transition energies.

Sustainable Hydrogen Production by Glycerol and Monosaccharides Catalytic Acceptorless Dehydrogenation (AD) in Homogeneous Phase.

In the quest for sustainable hydrogen production, the use of biomass-derived feedstock is gaining importance. Acceptorless Dehydrogenation (AD) in the presence of efficient and selective catalysts has been explored worldwide as a suitable method to produce hydrogen from hydrogen-rich simple organic molecules. Among these, glycerol and sugars have the advantage of being cheap, abundant, and obtainable from fatty acid basic hydrolysis (biodiesel industry) and from biomass by biochemical and thermochemical processing, respectively. Although heterogeneous catalysts are more widely used for hydrogen production from biomass-based feedstock, the harsh reaction conditions applied limit applicability due to deactivation of active sites due to coking of carbonaceous materials. Moreover, heterogeneous catalyst are more difficult to fine-tune than homogeneous counterparts, and the latter also allow for high process selectivities under milder conditions. The present Concept article summarizes the main features of the most active homogeneous catalysts reported for glycerol and monosaccharides AD. In order to directly compare hydrogen production efficiencies, the choice of literature works was limited to reports where hydrogen was clearly quantified by yields and turnover numbers (TONs). The types of transition metals and ligands is discussed, together with a perspective view on future challenges of homogeneous AD reactions for practical applications.

Unveiling the potential of lithium fluoride phosphate (Li2MPO4F, M = Fe, V, Mn) for the next generation of lithium-ion batteries: A comparative study based on first principles and molecular dynamic simulations

LiFePO4 (LFP) cathode with olivine crystal structure has been a key player in safe and affordable energy storage, owing to its low-cost iron and high electrochemical stability within a voltage range of commercial electrolytes (2.8–3.4 V). To maintain these benefits while enhancing its energy density, Li2MPO4F was developed by introducing fluorine (F) and replacing iron with other transition metals (M). However, previous studies on these materials primarily measured performance within a limited voltage window (e.g., 2.5–4.5 V), making it challenging to analyze their performance under advanced electrolytes with a broader voltage range. In this study, we took a novel approach by utilizing first principles and molecular dynamic calculations to investigate the electrochemical performance of Li2MPO4F with three types of transition metals (M = V, Fe, Mn). This unique methodology, which includes calculations on theoretical voltages, atomic structures, and diffusion coefficient after structural optimization, allowed us to predict the impact of transition metals on cathode performance. By closely comparing the expected results, this study discusses the pros and cons of each cation substitution and suggests suitable cathode materials for batteries with high energy density and superior rate capability.

Promising corrosion resistance of mild steel, copper, and aluminum in hydrochloric acid solution using an environmentally friendly corrosion inhibitor

The current study assessed the anticorrosion features of 6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-carbaldehyde (AIM) in mitigating corrosion of three different metals: Mild Steel (MS), Copper (Cu) and Aluminum (Al) in 1 M HCl solution. The adsorption process of AIM on these metal surfaces, as well as the stability of the adsorbed layer and its relationship with the type of metal were comprehensively investigated. To achieve our objectives, several techniques were used, such as: Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), SEM surface characterization, and theoretical approaches. Electrochemical impedance spectroscopy investigations revealed high corrosion inhibition rates, reaching 99.01 %, 96.06 %, and 84.8 % for Cu, MS and Al, respectively, at a concentration of 10−3 M of AIM. Potentiodynamic polarisation validated the mixed type nature of inhibitor, a satisfactory correlation was observed between the results obtained by EIS and those obtained by the PDP technique. The adsorption study showed that the process was mainly controlled by chemical adsorption, and metal dissolution was an endothermic process. Additionally, surface analysis by scanning electron microscopy (SEM) confirmed the formation of a protective AIM film on the electrode surface, resulting in a significant reduction in metal dissolution in the presence of aggressive ions. The exploration of the relationship between molecular structure, inhibitory properties of AIM and the studied metals, was conducted through quantum chemical analysis and dynamic molecular simulation.

Mofs-derived transition metal carbon-based compounds supported Au-Pt catalyst for the catalytic oxidation of glycerol to glyceric acid

Accurately controlling the directional activation of the primary and secondary hydroxyls and preventing the deep oxidation of oxygen-containing functional groups and the degree of C–C cleavage is still a great challenge for the selective oxidation of glycerol to glyceric acid. Hence, a series of bimetallic Au-Pt/MxOyCz catalysts (M = Cu, Co, Ce, Mn, Ni, Zn, Zr) were prepared using MOFs-derived transition metal carbon-based compounds as the support. These catalysts were utilized for glycerol catalytic oxidation to glyceric acid under basic conditions. The experimental date indicated that the type of transition metal makes a big difference on the conversion of glycerol and the selectivity of glyceric acid under the mild condition of 60 ℃. Among them, the Mn-modified carbon-based compound supported Au-Pt/MnxOyCz catalyst has the best catalytic activity. After reaction for 2 h, the conversion of glycerol could reach 100 %, and the selectivity of glyceric acid could reach 57.3 %. The reason for the best activity of the Au-Pt/MnxOyCz catalyst is that the particle size of active molecules is small, and the strong metal-support interaction produces more active sites. Specifically, Au-Pt/MnxOyCz catalyst forms an Au-Pt alloy, and the synergy between alloyed Au-Pt and Mn&+ enhances the acidity of the catalyst, causing it to produce the most acidic sites and promoting the dispersion of metal nanoparticles. The strong basic site of the catalyst can promote Au-Pt electron transfer, which in turn changes the reducing properties of Au-Pt and enriches the oxygen vacancies of the catalyst. Therefore, the synergistic interaction between the acidic sites and strong basic sites promotes the activation of Au-Pt, which in turn promotes the reduction of Mn-based oxides and the activation and migration of oxygen. This work will offer some new recommendations for the development of MOFs-derived transition metal-based catalysts for the catalytic oxidation of bio-polyols under mild conditions.

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Damage power enhancement of fuel air explosive with typical metal hydrides additions

To study the damage power enhancement of fuel air explosive (FAE) with metal hydrides, the effects of metal hydrides (TiH2, MgH2, ZrH2) powders on shock wave and thermal damage of pure propylene oxide (PO) were explored using a 20 L spherical explosion test system combined with colorimetric thermometry technology. The experimental results showed that compared with the base metal powders, the explosion overpressures, maximum pressure rise rates and maximum average temperatures of the solid-liquid mixed fuel with the metal hydrides (TiH2, MgH2, ZrH2) powders increased by 11.04 %, 22.61 %, 4.80 % and 26.68 %, 38.18 %, 13.91 % as well as 6.85 %, 8.57 %, 1.34 %, respectively. Furthermore, the effects of metal hydride powders on the cloud explosion fuel were better than those of Al powders, and MgH2 powders had the most significant effects on the damage power enhancement of pure PO. Metal hydride powders as high-energy additives could improve the energy release characteristics of FAE.

Electronic structure modulation of yttrium sites with heteroanions coordination enhances the bidirectional catalytic performance of lithium-sulfur batteries

Oxyfluorides exhibit unique properties, including catalytic activity and electrical conductivity. However, to date, there has been minimal application of oxyfluorides in the field of lithium-sulfur (Li-S) batteries. This study synthesizes yttrium oxyfluoride-doped semi-encapsulated porous carbon nanofibers (YOF@PCNFs) using through electrospinning strategy for the separator coating in Li-S batteries. The precisely engineered OF heteroanionic environment surrounding the Y cation can adjust the lattice spacing and electronic density of the catalyst. This enhancement improves interactions between the active sites and the reactants, intermediates, and products, reduces the energy barrier for polysulfide (LiPSs) conversion, and enhances the bidirectional catalytic conversion capability of LiPSs. Furthermore, the semi-encapsulated structure helps inhibit polysulfide shuttle and ensures uniform Li-ion deposition. Improved catalysts and the interconnected special structure can establish a series of polysulfides conversion factories which operate efficiently over the long term through a “confinement-adsorption-catalysis-desorption” process, thereby enhancing battery cycling stability. The assembled Li-S full cell exhibits a high initial capacity of 1013.2 mAh/g at 1 mA cm−2 and maintains steady operation over 1500 cycles, with a minimal capacity decay rate of only 0.039 % per cycle. Even at a high current density of 4 mA cm−2, it operates for 200 cycles with an exceptionally low decay rate of 0.081 % per cycle. The study provides an anion hybrid strategy for typical metal catalysts, offering design guidelines for tailored advanced Li-S catalysts.

Investigation of the main regularities of glycolysis of polycarbonate plastic during catalysis by basic agents

This research focuses on analyzing how different primary catalysts affect the glycolysis of plastic made from bisphenol A (PC) polycarbonate. It was found that the process of chemical decomposition of PC under the influence of ethylene glycol (EG) leads to the formation of products with high added value: bisphenol A (PC monomer, BPA), BPA, and ethylene carbonate or ethylene glycol co-ethers (BPA monohydroxyethyl ether, MHE-BPA; BPA bishydroxyethyl ether, BHE-BPA). A quantitative assessment of the yields of the reaction products was also carried out. The yield of products at 100% PC conversion was 33% for BPA, 50% for MHE-BPA, and 17% for BHE-BPA. The effectiveness of using various alkalis depending on the type of metal was also compared within the context of this investigation.

Magneto-optical Goos–Hänchen shift in uniaxial anisotropic epsilon-near-zero metamaterials

Abstract We theoretically investigate the enhancement of the magneto-optical Goos-Hänchen (MOGH) shift in multilayer structure combining uniaxially anisotropic epsilon-near-zero (ENZ) metamaterials with magneto-optical (MO) materials. The structure enables the excitation of magneto-optical surface plasmon resonance (MOSPR) without the need for a prism or grating coupler, thereby achieving a significant enhancement of the MOGH shift. The effect of the thickness of the ENZ layer and the type of magnetic metal in this structure on the MOGH shift is also discussed. Based on the above structure, we design a high-sensitivity miniature biosensor that is used for the detection of hemoglobin concentration in human blood. The maximum sensitivity achievable with this sensor is 1.4×106 λ/RIU. The results of this investigation contribute to the development of biosensors towards miniaturization and integration.

Solar Light Elimination of Bacteria, Yeast and Organic Pollutants by Effective Photocatalysts Based on Ag/Cr-TiO2 and Pd/Cr-TiO2.

This study focused on searching for more effective nanomaterials for environmental remediation and health protection; thus, coliform bacteria, yeast and the organic food dye sunset yellow were selected as target pollutants to be eliminated under solar light by Ag/Cr-TiO2 and Pd/Cr-TiO2. Firstly, Cr3+ was in situ incorporated into the anatase crystalline lattice by the sol-gel method; then, Ag or Pd nanoparticles were deposited on Cr-TiO2 by chemical photoreduction. The scientific challenge addressed by the development of these composites was to analyse the recovery of Cr, to be employed in photocatalyst formulation and the enhancement of the TiO2 photocatalytic activity by addition of other noble metals. By extensive characterization, it was found that after TiO2 doping with chromium, the parameters of the crystal lattice slightly increased, due to the incorporation of Cr ions into the lattice. The TiO2 band gap decreased after Cr addition, but an increase in the optical absorptions towards the visible region after noble metals deposition was also observed, which was dependent of the Ag or Pd loading. Generally, it was observed that the noble metals type is a factor that strongly influenced the effectiveness of the photocatalysts concerning each substrate studied. Thus, by using Ag(0.1%)/Cr-TiO2, the complete elimination of E. coli from samples of water coming from a highly polluted river was achieved. Pd(0.5%)/Cr-TiO2 showed the highest efficiency in the elimination of S. cerevisiae from a lab prepared strain. On the other hand, the Pd(0.1%)/Cr-TiO2 sample shows the highest dye degradation rate, achieving 92% of TOC removal after 180 min.

A Possible Formation Scenario of the Gaia BH1: Inner Binary Merger in Triple Systems

Based on astrometric measurements and spectral analysis from Gaia DR3, two quiescent black hole (BH) binaries, Gaia BH1 and BH2, have been identified. Their origins remain controversial, particularly for Gaia BH1. By considering a rapidly rotating (ω/ω crit = 0.8) and strongly magnetized (B 0 = 5000 G) merger product, we find that, at typical Galactic metallicity, the merger product can undergo efficient chemically homogeneous evolution. This results in the merger product having a significantly smaller radius during its evolution compared to that of a normally evolving massive star. Under the condition that the initial triple stability is satisfied, we use the Multiple Stellar Evolution code and the MESA code to identify an initial hierarchical triple that can evolve into Gaia BH1. It initially consists of three stars with masses of 9.03 M ⊙, 3.12 M ⊙, and 1 M ⊙, with inner and outer orbital periods of 2.21 days and 121.92 days, and inner and outer eccentricities of 0.41 and 0.45, respectively. This triple initially experiences triple evolution dynamics instability (TEDI) followed by Roche lobe overflow (RLOF). During RLOF, the inner orbit shrinks, and tidal effects gradually suppress the TEDI. Eventually, the inner binary undergoes a merger through contact (or collision). Finally, using models of rapidly rotating and strongly magnetic stars, along with standard core-collapse supernova (SN) or failed supernova (FSN) models, we find that a postmerger binary (PMB) consisting of an 12.11 M ⊙ merger product and a 1 M ⊙ companion star (originally an outer tertiary) can avoid RLOF. After an SN or FSN with a low ejected mass of ∼0.22 M ⊙ and a low kick velocity ( 46−33+25kms−1 or 9−8+16kms−1 ), the PMB can form Gaia BH1 in the Galactic disk.

Computational Exploration of the Impact of Low‐Spin and High‐Spin Ground State on the Chelating Ability of Dimethylglyoxime Ligand on Dihalo Transition Metal: A QTAIM, EDA, and CDA Analysis

ABSTRACTWe have explored the chelation of dimethylglyoxime ligand to divalent (ndx: x = 6, 7, 8) transition metal (TM) cations in two media (gas phase and water) at the B3LYP//LANL2DZ/6–311+G (d,p) and B3LYP/def2‐TZVP level at lower multiplicity and higher multiplicity states. Majority of the 18 optimized halide (chloride and bromide) complexes prefer square planar configuration. The correlations discerned between the experimental structural data and their estimated counterparts demonstrate a good credibility for complexes at lower multiplicity state. The basis set superposition errors (BSSEs) estimated is very small which reflects the fact that the choice of different basis sets (B3LYP//LANL2DZ/6–311+G (d,p)) introduces a slight bias in the calculation of energies. The ADMP (atom‐centered density matrix propagation) simulations in water on chloride complexes indicate the irreversible nature of these M—N dissociation in trajectory simulation process. This fact explains our exclusive focus on the examination of the [glyoxime ligand]…[MX2] interactions. In addition, the solvation of (3d and 4d) transition metal chloride complexes causes a sensitive augmentation of the metal ion affinity (MIA) with an average of 0.29 and 0.24 kcal/mol. In both multiplicity states, the topological parameters have illustrated that the M—N and M—X bonds are typical metal–ligand in both media. The average ΔEorb/ΔEsteric ratio equal to 0.45 and 0.11 in gas phase and water, respectively, reveals the predominance of the contributions from non‐covalent bonding interactions (NCI) compared to those of covalent bonding. But, the maximal value equal to 6.760 is obtained for bromide rhodium complex in water. NBO analysis in both media highlights the fact that a more pronounced ionic character is observed for the majority of the chloride complexes at both spin multiplicity states because of their higher retained charges on the metal atom. For [dimethylglyoxime]…[MX2] interaction (X = Cl and Br), the charge decomposition analysis demonstrates that the lowest value of the d/b ratio is found for the chloride platinum complex at lower multiplicity state in water. This is a proof of its strong relativistic effects.

Identifying the antecedents for the green transformation of resource-exhausted cities in China

To address the issue of green transformation in resource-exhausted cities, this study employs the Policy Modeling Consistency (PMC) index model to carry out a comprehensive analysis of the effectiveness of support policies execution at both central and local levels, covering 16 policies at the different administrative levels. Meanwhile, utilizing the fuzzy-set Qualitative Comparative Analysis (fsQCA) method, the study investigates the interaction mechanisms and effects of various internal and external factors in the context of policy coordination, from the perspective of green transformation condition configurations. The findings reveal that the overall effect of supporting policies for resource-exhausted cities in China is generally commendable. Moreover, there is a notable characteristic that “the lower the administrative level, the higher the quality of the support policies”. Notably, organizational, technological, environmental, and policy conditions alone cannot solely facilitate the green transition of resource-exhausted cities. Instead, it is the harmonious configuration of these antecedents that drives successful green transformation. Additionally, the configuration of antecedent conditions for green transformation exhibits the heterogeneity of different types. Specifically, the eastern region primarily relies on technological innovation and production process improvement, while the central region focuses on both production process improvement and support policy combinations. By contrast, the western region primarily emphasizes support policy combinations and the fostering of environmental conditions. Furthermore, the green transformation of resource-exhausted cities with coal and oil types mainly depends on the combination of policy support and technological innovation. Metal, forestry, and other types of resource-exhausted cities rely on the upgrading and advancement of industrial structures. In the grouped analysis of administrative level, innovation capability, and distance to the provincial capital city, cities with higher administrative levels, higher innovation capabilities, and closer proximity to the provincial capital city are more likely to achieve green transformation. Thereby, this study emphasizes the critical role of support policies and the identification of effective pathways in promoting the green transformation of resource-exhausted cities.

Atomic cluster expansion interatomic potential for defects and thermodynamics of Cu–W system

The unique properties exhibited in immiscible metals, such as excellent strength, hardness, and radiation-damage tolerance, have stimulated the interest of many researchers. As a typical immiscible metal system, the Cu–W nano-multilayers combine the plasticity of copper and the strength of tungsten, making it a suitable candidate for applications in aerospace, nuclear fusion engineering, and electronic packaging, etc. To understand the atomistic origin of the defects (e.g., vacancies, free surfaces, grain boundaries, and stacking faults and thermodynamical properties), we developed an accurate machine learning interatomic potential for Cu–W based on the atomic cluster expansion (ACE) method. The Cu–W ACE potential can faithfully reproduce the fundamental properties of Cu and W predicted by density functional theory (DFT) calculations. Moreover, the thermodynamical properties, such as the melting point, coefficient of thermal expansion, diffusion coefficient, and equation of the state curve of the Cu–W solid solution, are calculated and compared against DFT and experiments. Monte Carlo molecular dynamics simulations performed with the Cu–W ACE potential predict the experimentally observed phase separation and uphill diffusion phenomena. Our findings not only provide an accurate ACE potential for describing the Cu–W immiscible system but also shed light on understanding the atomistic mechanism during the Cu–W nano-multilayers formation process.

Acid Mine Drainage Neutralization by Ultrabasic Rocks: A Chromite Mining Tailings Evaluation Case Study

Chromite is formed in nature in ophiolitic layers and ultrabasic rocks through fractional crystallization. The corresponding mining technologies separate the ore from these ultrabasic rocks, which are considered to be tailings for the process but may be valorized in other applications. The need to utilize this material is due to the large quantities of its production and the special management required to avoid possible secondary pollution. In the present work, the ultrabasic rocks of chromite mining were applied to acid mine drainage (AMD) neutralization. The aim was to increase the technological maturity of the method and promote circular economy principles and sustainability in the mining sector. Ultrabasic rocks were obtained from a chromite mining facility as reference material. Furthermore, an artificial AMD solution was synthesized and applied, aiming to simulate field conditions. According to the results, the sample was successfully utilized in AMD neutralization (pH 7), achieving rapid rates in the first 30 min and maximum efficiency (liquid to solid ratio equal to 8.3) at 24 h. However, the method presented a drawback since Mg was leached, even though the concentration of other typical metals contained in an AMD solution decreased.

Synthesis of Silver Nanoparticles (NPPs) Using Xylocarpus Granatum Fruit Extract and its Application in Heavy Metal Pollution Detection

Heavy metals are dangerous pollutants because they are toxic, non-biodegradable, and stable. Mercury (Hg) is a type of heavy metal that is often a source of pollution in the aquatic environment. The biosynthesis process of nanoparticles using Xylocarpus granatum fruit extract as a bioreductant has been carried out using the green synthesis method. The research was conducted to synthesize silver nanoparticles (NPP) from Xylocarpus granatum fruit extract to detect heavy metals. The optimum condition of NPP was obtained through the comparison of AgNO3 concentration with extract and reaction time. The optimum NPP produced was at a concentration of AgNO3 1 mM 1:1 at a synthesis time of 2 hours. The NPP formed is selective to Hg metal as can be seen from the color change of NPP from dark brown to clear and sensitive to Hg metal at a concentration of 40 ppm. The calibration curve formed obtained a linear regration value of the relationship between the concentration of Hg standard solution and absorbance, namely y = -0.01330 + 3.71658 with a coefficient of determination (R2) value of 0.99229. Based on the standard curve obtained NPP mangrove fruit extract Xylocarpus granatum has an accuracy of 99.229% in predicting the concentration of the sample.

Natural coil springs: Biomechanics and morphology of the coiled tendrils of the climbing passion flower Passiflora discophora

Tendrils of climbing plants possess a striking spring-like structure characterized by a minimum of two helices of opposite handedness connected by a perversion. By performing tensile experiments and morphological measurements on tendrils of the climbing passion flower Passiflora discophora, we show that these tendril springs act as coil springs within the plant's attachment system and resemble technical coil springs. However, tendril springs have a low spring index and a high pitch angle compared with typical metal coil springs resulting in a more complex loading situation in the plant tendrils. Moreover, the tendrils undergo a drastic shift from the fresh turgescent stage to a dried-off and dead senescent stage. This entails changes in material properties (elastic modulus in tension), morphology (tendril and helix diameter, number of windings), anatomy (tissue composition), and failure behavior (susceptibility to delamination) and reduces the degree of elasticity and strain at failure of the tendrils. Nevertheless, senescent tendrils remain functional as springs and maintain high energy dissipation capacity and high break force. This renders the system highly energy efficient, as the plant no longer needs to metabolically sustain the died-back tendrils. Because of its energy-storing spring system, its high energy dissipation and high safety factor, the attachment system can be considered a ‘fail-safe’ system. Statement of significanceThe use of coil springs as mechanical devices is not restricted to man-made machinery; striking spring structures can also be found within the attachment systems of climbing plants. Passiflora discophora climbs by using long thin tendrils with adhesive pads at their tips. Once the pads have attached to a support, the tendrils coil and form a spring-like structure. Here, we analyze the form and mechanics of these ‘tendril springs’, compare them with conventional technical coil springs, and discuss changes in the tendril springs during plant development. We reveal the main features of the attachment system, which might inspire new artificial attachment devices within the emerging field of plant-inspired soft-robotics.