Crystalline Structure Properties Research Articles

Facile Preparation of PVDF/CoFe2O4-ZnO Hybrid Membranes for Water Depollution.

In this investigation, CoFe2O4-PVDF and CoFe2O4-ZnO-PVDF hybrid membranes were prepared using a modified phase inversion method in which a magnetic field was applied during the casting process to ensure a uniform distribution of nanomaterials on the membrane surface. Thus, better absorption of light and increased participation of nanoparticles in the photodegradation process is ensured. The influence of nanomaterials on the crystalline structure, surface morphology, and hydrophilicity properties of the PVDF membrane was investigated. The obtained results indicated that the hybrid membrane exhibited significant differences in its intrinsic properties due to the nanomaterials addition. The hydrophilicity properties of the PVDF membrane were improved by the presence of nanoparticles. The photocatalytic decomposition of aqueous Rhodamine B solution in the presence of the prepared membrane and under visible light irradiation was tested. The hybrid membrane containing CoFe2O4-ZnO on its surface exhibited a high removal rate.

Insight into Crystalline Structure and Physicochemical Properties of Quartz-Carbon Ore

Composites made from carbon and nanominerals show great potential for thermal phase change materials, environmental water treatment, and biomass conversion. In 2019, a micro and nano-quartz-carbon ore was discovered in Feng-cheng City, Jiangxi Province. The study of the structural and physicochemical changes of quartz-carbon ore (QZC) during calcination is essential for the preparation of QZC-based composites and to broaden their application areas. Firstly, the SiO2 crystal structure evolution of QZC during calcination was investigated using in-situ X-ray diffraction (XRD), 29Si magic-angle sample spinning nuclear magnetic resonance (MAS NMR), and Fourier transform infrared FTIR spectroscopy. Then, the changes in carbon during calcination were investigated using Raman spectroscopy, 13C MAS NMR, and X-ray photoelectron spectroscopy (XPS). In addition, changes in the QZC morphology were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Finally, the evolution of the physicochemical properties of QZC during calcination was revealed using thermogravimetric (TG), Brunauer–Emmet–Teller (BET), resistivity, thermal conductivity, and zeta potential techniques.

Waxes from Long-Chain Aliphatic Difunctional Monomers.

Petrochemical polyethylene waxes (Mn = 800-8000 g/mol for commercial Ziegler waxes) as additives, lubricants, and release agents are essential to numerous products and production processes. The biodegradability of this class of compounds when unintentionally released to the environment is molar mass dependent and subject to ongoing discussions, and alternatives to conventional polyethylene waxes are desirable. By employing bottom-up and top-down approaches, that is nonstoichiometric A2 + B2 polycondensation and chain scission, respectively, linear waxes with multiple in-chain ester groups as biodegradation break points could be obtained. Specifically, waxes with 12,12 (WLE-12,12, WLE = waxes linear ester) and 2,18 (WLE-2,18) carbon atom linear ester repeat unit motifs were accessible over a wide range of molar masses (Mn ≈ 600-10 000 g/mol). In addition to the molar mass, the type of end group functionality (i.e., methyl ester, hydroxy, or carboxylic acid end groups) significantly impacts the thermal properties of the waxes, with higher melting points observed for carboxylic acid end groups (e.g., Tm = 83 °C for carboxylic acid-terminated WLE-12,12 with Mn,NMR = 1900 g/mol, Tm = 92 °C for WLE-2,18 with Mn,NMR = 2200 g/mol). A HDPE-like orthorhombic crystalline structure and rheological properties comparable to a commercial polyethylene wax suggest WLE-12,12 and WLE-2,18 are viable biodegradable and biosourced alternatives to conventional, petrochemical polyethylene waxes.

Effect of non-starch components on the structural properties, physicochemical properties and in vitro digestibility of waxy highland barley starch

Highland barley (HB) endosperm with an amylose content of 0–10 % is called waxy HB (WHB). WHB is a naturally slow-digesting grain, and the interaction between its endogenous non-starch composition and the WHB starch (WHBS) has an important effect on starch digestion. This paper focuses on the mechanisms by which the components of β-glucan, proteins and lipids affect the molecular, granular, crystalline structure and digestive properties of WHBS. After eliminating the main nutrients except for starch, the estimated glycemic index (eGI) of the samples rose from 62.56 % to 92.93 %, and the rapidly digested starch content increased from 60.81 % to 98.56 %, respectively. The resistant starch (RS) content, in contrast, dropped from 38.61 % to 0.13 %. Comparatively to lipids, β-glucan and protein contributed more to the rise in eGI and decline in RS content. The crystalline characteristics of starch were enhanced in the decomposed samples. The samples' gelatinization properties improved, as did the order of the starch molecules. Protein and β-glucan form a dense matrix on the surface of WHBS particles to inhibit WHBS digestion. In summary, this study revealed the mechanism influencing the digestibility of WHBS from the perspective of endogenous non-starch composition and provided a theoretical basis to develop slow-digesting foods.

Enhanced energy storage performance of (Bi0.5Na0.5)TiO3–SrTiO3 ceramics doped with ZrO2

This study presents a novel lead-free ceramics system (Bi0.25Na0.25Sr0.5)(Ti1-xZrx)O3 by introducing ZrO2 to 0.5(Bi0.5Na0.5)TiO3-0.5SrTiO3 ceramics. The effects of Zr4+ addition on the crystalline structure, dielectric and ferroelectric properties have been investigated. The average grain size decreases during the introduction of Zr4+, improving the breakdown strength. With the increase of doping amount, the dielectric constant and dielectric loss decrease significantly, and the dependence on temperature and frequency becomes weaker obviously. Furthermore, the hysteresis loops of the optimized ceramics become thinner and the polarization saturation trend weakened obviously. The recoverable energy density of 1.89 J/cm3 and the energy storage efficiency of 70.3 % was obtained in the (Bi0.5Na0.5Sr0.5)(Ti0.88Zr0.12)O3 ceramics, which also showed good temperature and frequency stability over a wide range. The novel lead-free relaxor ceramics investigated in this study have significant advantages and promising for the frequency-stable and thermal-stable energy storage capacitor applications.

Synthesis of CuInS2 nanoparticles and application in the photocatalytic degradation of tetracycline

A lot of effort has been given to the development of nontoxic ternary semiconductor nanoparticles that could act as photocatalyst NIR-I (750–850 nm) or NIR-II (1000–1400 nm) optical windows. This is due to their good stability, high optical absorption coefficient, and desirable band gap that absorbs well within the solar spectrum. CuInS2 is one of the ternary sulphide semiconductors, which has been considered to be a highly promising photocatalyst. The properties are attributed to its high optical absorption coefficient. In this study, copper indium sulphide (CuInS2) nanoparticles were synthesized by a microwave irradiation route using copper(II) bis (N-methyl-N-ethanol dithiocarbamate) and In(III) tris (N-methyl-N-ethanol dithiocarbamate) as a precursor complexes. The copper(II) complex was varied in two different ratios (3:1 and 2:1) to determine the best synthesis regime. Then, the effect of the varying ratios on the crystalline structure, morphology, and optical properties of the CuInS2 was studied by using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and absorption spectroscopy. The microscopic analyses revealed that the CuInS2 nanoparticles have similar spherical grain-like shapes whose sizes range between 10.3–50.1 nm. The increase in the concentration of copper(II) complex also altered the band gap energy, given 2.87 and 1.61 eV for CuInS2(3:1) and CuInS2(2:1) respectively. The photocatalytic activities of the nanoparticles were determined for the degradation of Tetracycline (TC) under visible light irradiation. The effects of process parameters such as photocatalyst dosage and initial concentration of TC were investigated to establish the optimal performance of the CuInS2 nanoparticles. The experimental data showed a higher TC degradation percentage for CuInS2(2:1) (95 %) compared to CuInS2(3:1) (90 %), indicating its high potential as a photocatalyst for the degradation of TC in aqueous solution.

Thermo and photoluminescence studies of Eu3+, Dy3+ co-doped Sr2SiO4 nanophosphor prepared by solution combustion method

Sr2SiO4: Eu0.01 phosphors co-doped with Dy3+ was prepared by solution combustion method at a low temperature of 500°C. The effect of co-dopant on the luminescent properties of Sr2SiO4: Eu was investigated in detail. The crystalline size and structural properties are studied by X-ray diffraction. The peaks of Sr2SiO4 are assigned by FTIR studies. Which shows that dopants have occupied the position of Sr2+ ions in the crystal. The morphology and size distribution of phosphors was examined by SEM. Image looks like thermocole particles in thermocole sheet. The photoluminescence (PL) intensity of Sr2SiO4: Eu co-doped with Dy3+ shows emission in all the three regions red, blue and green. Thermoluminescence (TL) of Sr2SiO4: Eu co-doped with Dy3+ was investigated using γ-irradiation for different mol% of Dy3+ in the dose range of 1–6 KGy at a warming rate of 5 °C/s.

CoCrFeNiSi high entropy alloy: Synthesis, structural and radiation shielding properties

High entropy alloys (HEAs) have emerged as a distinct class of alloys with unique design strategies, different from traditional alloys. These alloys hold great promise for diverse applications, and the investigation of their nuclear radiation shielding properties has become an important and emerging area of research. In this experimental study, an equimolar CoCrFeNiSi HEA was prepared using the ball milling method. The focus was on characterizing the crystalline structure, morphological features, and radiation shielding properties of the synthesized HEA. X-ray diffraction analysis revealed that the HEA exhibited a face-centered cubic (FCC) phase structure. The crystallite size was significantly reduced from 23.63 nm to 3.22 nm, indicating the refinement of the microstructure. The homogeneity of the alloy was confirmed through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), which showed that the five elements were uniformly distributed within the powder alloy. To evaluate the radiation shielding properties, linear attenuation coefficients (LAC) of the CoCrFeNiSi HEA powder were measured using a 662 keV gamma source and a NaI(Tl) detector system (ORTEC® 905–4). The experimental LAC values were determined to be 0.2140 ± 0.01 cm⁻1. Theoretical calculations using MCNP6.2 and XCOM code were also performed and showed good agreement with the experimental results. Comparing the CoCrFeNiSi HEA with common shield materials such as thin films, glass systems, and some composites, it was found that the HEA outperformed them in terms of radiation shielding effectiveness. This demonstrates the potential of the CoCrFeNiSi HEA as an advanced alternative to conventional shielding materials, with potential applications in various fields.

Physico-chemical characterization and photocatalytic activity assessment under UV-A and visible-light irradiation of iron-doped TiO2 nanoparticles

In this work, undoped TiO2 and Fe-doped TiO2 materials as photocatalysts for water remediation, were synthesized using wet chemical methods (sol–gel + precipitation). Their crystalline structure, optical and morphological properties were explored using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopies, UV–vis diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy coupled to the energy dispersive X-Ray spectroscopy (SEM-EDS). The photocatalytic performance of the synthesized materials was assessed through the degradation of methyl orange (MO) under UV-A and visible-light irradiations. The structural study showed the existence of predominate anatase phase in all synthesized nanomaterials. The optical study showed a widening of the band gap for Fe-doped TiO2 materials and revealed a decrease in charge carrier’s recombination for all Fe-doped TiO2 nanomaterials compared to undoped TiO2. The morphological study confirmed the nanometric scale of the materials particles. The photocatalytic experiments revealed an enhanced photocatalytic activity of 0.5 %wt Fe-doped TiO2, only under UV-A light, compared to the rest of the prepared nanomaterials. The enhanced photocatalytic activity has been attributed to the efficient charge separation of electrons and holes.

Pressure-Driven Structural and Electronic Transitions in a Two-Dimensional Janus WSSe Crystal.

In this work, we presented the first report on the high-pressure structural stability and electrical transport characteristics in WSSe under different hydrostatic environments through Raman spectroscopy, electrical conductivity, and high-resolution transmission electron microscopy (HRTEM) coupled with first-principles theoretical calculations. For nonhydrostatic conditions, WSSe endured a phase transition at 15.2 GPa, followed by a semiconductor-to-metal crossover at 25.3 GPa. Furthermore, the bandgap closure was accounted for the metallization of WSSe as derived from theoretical calculations. Under hydrostatic conditions, ∼ 2.0 GPa pressure hysteresis was detected for the emergence of phase transition and metallization in WSSe because of the feeble deviatoric stress. Upon depressurization, the reversibility of the phase transition was substantiated by those of microscopic HRTEM observations under different hydrostatic environments. Our high-pressure investigation on WSSe advances the insightful understanding of the crystalline structure and electronic properties for the Janus transition-metal dichalcogenide (TMD) family and boosts prospective developments in functional devices.

Investigating the properties of nano crystalline beta metal-free phthalocyanine films: From molecules to optoelectronic applications

A study was conducted to investigate the structural and optical properties of nanocrystalline beta metal-free phthalocyanine (β-H2Pc) thin films using computational and experimental methods. DFT calculations using the B3LYP basis set 6–311G were performed to predict the HOMO-LUMO gap of the β-H2Pc (2.13 eV). The crystalline structural properties of the β-H2Pc were examined through XRD analysis, which revealed that the powder β-H2Pc had a monoclinic polycrystalline structure, while the β-H2Pc thin film was amorphous. Various methods were used to determine and compare the average crystallite size and microstrain, with the size-strain plot method yielding an average crystallite size and microstrain size of 73.15 nm and 0.0051, respectively. Using SEM to analyze the film's surface topography, the mean grain size was found to be 0.85 µm due to agglomeration. Linear and nonlinear spectrophotometric measurements were employed to examine the optical properties of the β-H2Pc thin film. The film exhibited indirectly permitted inter-band transitions, with the onset and fundamental band gaps of 1.51 eV and 2.74 eV, respectively. Furthermore, several absorption and dispersion characteristics for thin films were identified. The properties exhibited by Au/β-H2Pc/p-Si/Al heterojunction indicate its potential suitability for photosensor applications.

Shaping of HKUST-1 via Extrusion for the Separation of CO2/CH4 in Biogas

HKUST-1 is a metal-organic framework (MOF) that is widely studied as an adsorbent for CO2 capture because of its high adsorption capacity and good CO2/CH4 selectivity. However, the numerous synthesis routes for HKUST-1 often result in the obtention of MOF in powder form, which limits its application in industry. Here, we report the shaping of HKUST-1 powder via the extrusion method with the usage of bio-sourced polylactic acid (PLA) as a binder. The characterization of the composite was determined by XRD, FTIR, TGA and SEM analyses. The specific surface area was determined from the N2 adsorption isotherm, whereas the gas adsorption capacities were investigated via measurements of CO2 and CH4 isotherms of up to 10 bar at ambient temperature. The material characterization reveals that the composite preserves HKUST-1’s crystalline structure, morphology and textural properties. Furthermore, CO2 and CH4 adsorption isotherms show that there is no degradation of gravimetric gas adsorption capacity after shaping and the composite yields a similar isosteric adsorption heat as pristine HKUST-1 powder. However, some trade-offs could be observed, as the composite exhibits a lower bulk density than pristine HKUST-1 powder and PLA has no impact on pristine HKUST-1’s moisture stability. Overall, this study demonstrates the possibility of shaping commercial HKUST-1 powder, using PLA as a binder, into a larger solid-state-form adsorbent that is suitable for the separation of CO2 from CH4 with a well-preserved pristine MOF gas-adsorption performance.

Development of bismuth-rich bismuth oxyhalides based photocatalyst for degradation of a representative antibiotic under simulated solar light irradiation

In this study, the novel 2D/2D S-scheme Bi12O15Cl6/BiOCl heterojunction was fabricated using a facile solvothermal followed by a post-thermal treatment process. The samples were characterized by various modern spectroscopy techniques. A series of Bi12O15Cl6/BiOCl heterojunctions were prepared by adjusting the molar ratio of Bi:Cl and the calcination temperature. The crystalline structure, morphology, elemental composition, and optical properties of nanocomposites strongly depend on the synthesis conditions. The sample prepared with Bi:Cl molar ratio of 2.0:1 and calcined at 400 °C (BOC-2.0-400) containing 29.55 wt% of BiOCl and 70.45 wt% of Bi12O15Cl6, exhibited the highest efficiency in the degradation of CIP solution under simulated solar light irradiation. The reaction rate constant was 2.5 times and 1.8 times higher than that of pristine BiOCl and Bi12O15Cl6, respectively. Under the experimental conditions of catalyst dosage of 0.7 gL-1, initial CIP concentration of 10 mgL-1 and pH8.8, CIP was completely degraded within 150 min of irradiation over the BOC-2.0-400. Furthermore, radical scavenging studies signified that O2●–, h+ are evolved in photocatalytic process. The experimental and characterization results provided evidenc that the excellent photocatalytic performance of Bi12O15Cl6/BiOCl heterojunction was facilitated by the construction of S-scheme charge transfer route with compact interface of 2D/2D morphology. The S-scheme Bi12O15Cl6/BiOCl heterojunction exhibited excellent visible light absorption ability, high photogenerated charge separation efficiency and maintained strong redox capacity for electrons and holes during CIP photodegradation. These findings provide a potential strategy for designing S-scheme heterojunction-based bismuth-rich bismuth oxyhalide photocatalyst to eliminate antibiotic residues.

Effect of Octene Block Copolymer (OBC) and High-Density Polyethylene (HDPE) on Crystalline Morphology, Structure and Mechanical Properties of Octene Random Copolymer.

Blending octene random copolymer (ORC) with other polymers is a promising approach to improving ORC mechanical properties, such as tensile strength and elongation. In this study, octene block copolymer (OBC) with lower density than ORC and high-density polyethylene (HDPE) were used to blend with ORC. The effect of both OBC and HDPE on ORC was analyzed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and small-angle X-ray scattering (SAXS). For ORC/OBC blends, a small amount of OBC can improve the crystallization ability of ORC. Meanwhile, for ORC/HDPE blends, the crystallization ability of ORC was significantly suppressed, attributed to good compatibility between ORC and HDPE as indicated by the homogeneous morphology and the disappearance of the α transition peak of ORC in ORC/HDPE blends. Therefore, the tensile strength and elongation of ORC/HDPE blends are significantly higher than those of ORC/OBC blends. For ORC/OBC/HDPE ternary blends, we found that when ORC:OBC:HDPE are at a ratio of 70:15:15, cocrystallization is achieved. Although HDPE improves the compatibility of ORC and OBC, the three-phase structure of the ternary blends can be observed through SAXS when HDPE and OBC exceed 30 wt%. Blending HDPE and OBC (≤30 wt%) could improve the mechanical property of ORC.

Impact of amylose content on the formation of V-type granular starch

V-type granular starch (VGS) was prepared by aqueous-ethanol heat treatment using normal maize starch (NMS) with an amylose content of 31.02% (NMS1), 25.08% (NMS2), or 22.39% (NMS3). The effects of different amylose contents on VGS granular morphology, crystalline structure, thermal transitions, and cold-water paste viscosity properties were compared. Moreover, the effects of different temperature holding times (0–30 min) during aqueous-ethanol heat treatment on the formation of VGS were evaluated. The results showed that NMS1, for which the amylose content was the highest, required 5 min holding at 100 °C to reach the maximum V-type relative crystallinity (13.97%) and the highest cold-water paste viscosity (2981.28 cP) while maintaining the most intact granular morphology. Longer temperature holding periods caused damage to starch granules and decreased the formation of V-type crystals. Higher amylose content was beneficial for preservation of starch granule integrity and the formation of V-type crystals, resulting in a higher cold-water paste viscosity of VGS. However, starch with higher amylose contents required more energy to fully disorder amylose to form V-type complexes with ethanol.

Yeni Bir Schiff Bazı Molekülüne in Siliko Tıbbi ve Hesaplamalı Yöntemlerle Bir Bakış

In this study, the synthesis and characterization of a new Schiff base molecule, (E)-1-(5-nitro-2-(piperidin-1-yl) phenyl)-N-(4-phenoxyphenyl) methanimine, were aimed. In addition, the molecular surface area, crystalline structure, intermolecular forces, electronic and spectroscopic properties of the molecule were investigated. Docking studies were also performed on the active sites of the main protease (Mpro) of SARS-CoV-2, and the docking result was compared with the efficacy of the native ligand N3 inhibitor. The main findings for the title molecule can be summarized as follows: The space group is P-1 and it crystallizes in the triclinic system. The unit cell consists of two monomeric units (Z=2). There are strong electrophilic attack sites in the molecule, but nucleophilic centers have low efficiency. According to the FMO analysis, the title compound is a soft, kinetically and chemically unstable and highly reactive material. The value of the binding free energy calculated by docking experiments (-9.28 kcal mol-1) is lower than that of the native inhibitor (-7.11 kcal/mol) and thus can be considered as a potential inhibitor candidate for the main protease of SARS-CoV-2.

Blue/NIR-emitting Phosphor Based on Sr2CeO4: Tm3+, Yb3+ Obtained by Combustion Synthesis

In this study, pure Sr2CeO4 (SCO) and codoped Sr2CeO4:Tm3+, Yb3+ (SCO:Tm, Yb) of powder phosphors were synthesized by a combustion technique. The concentration of Tm3+ was fixed at 0.5 mol %, while the Yb3+ doping concentration was varied from 0 to 7.0 mol %. The crystalline structure, morphology and luminescence properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectroscopy, respectively. The XRD analysis shows the crystalline orthorhombic phase for all synthesized samples of SCO and SCO: Tm, Yb. The SEM results show that the doped sample with 5.0 mol % Yb3+ has the lowest grain particle size of 1.92 mm. The SCO:Tm, Yb phosphors produce mainly blue and near infrared emission bands centered at 481 nm and 813 nm (under 980 nm, excitation) which corresponds respectively to 1G4→3H6 and 3H4→3H6 transitions of Tm3+. In addition, the international commission on illumination CIE coordinates were calculated for all samples taking the range of 400 – 700 nm obtaining for the 5.0 mol % Tm3+ doped sample the coordinates: (x,y) = (0.0833, 0.1671) which match with pure blue color. Due to the strong blue and near infrared emissions, the SCO:Tm, Yb phosphors could be good candidates for use in biomarkers or lighting applications.

Synergistic Effect of Y Doping and Reduction of TiO2 on the Improvement of Photocatalytic Performance.

Pure TiO2 and 3% Y-doped TiO2 (3% Y-TiO2) were prepared by a one-step hydrothermal method. Reduced TiO2 (TiO2-H2) and 3% Y-TiO2 (3% Y-TiO2-H2) were obtained through the thermal conversion treatment of Ar-H2 atmosphere at 500 °C for 3 h. By systematically comparing the crystalline phase, structure, morphological features, and photocatalytic properties of 3% Y-TiO2-H2 with pure TiO2, 3% Y-TiO2, and TiO2-H2, the synergistic effect of Y doping and reduction of TiO2 was obtained. All samples show the single anatase phase, and no diffraction peak shift is observed. Compared with single-doped TiO2 and single-reduced TiO2, 3% Y-TiO2-H2 exhibits the best photocatalytic performance for the degradation of RhB, which can be totally degraded in 20 min. The improvement of photocatalytic performance was attributed to the synergistic effect of Y doping and reduction treatment. Y doping broadened the range of light absorption and reduced the charge recombination rates, and the reduction treatment caused TiO2 to be enveloped by disordered shells. The remarkable feature of reduced TiO2 by H2 is its disordered shell filled with a limited amount of oxygen vacancies (OVs) or Ti3+, which significantly reduces the Eg of TiO2 and remarkably increases the absorption of visible light. The synergistic effect of Y doping, Ti3+ species, and OVs play an important role in the improvement of photocatalytic performances. The discovery of this work provides a new perspective for the improvement of other photocatalysts by combining doping and reduction to modify traditional photocatalytic materials and further improve their performance.

In-situ monitoring of changes in ultrastructure and mechanical properties of flax cell walls during controlled heat treatment

Plant fibres are increasingly used as reinforcements, especially in thermoplastic composites. Understanding the impact of temperature on the properties of these fibres is an important issue for the manufacturing of high-performance materials with minimal defects. In this work, the structural evolution and mechanical behaviour of flax fibre cell walls were dynamically monitored by temperature-controlled X-ray diffraction and nanoindentation from 25 to 230 °C; detailed biochemical analysis was also conducted on fibre samples after each heating step. With increasing temperature up to 230 °C, a decrease in the local mechanical performance of the flax cell walls, of about −72 % for the indentation modulus and −35 % for the hardness, was measured. This was associated with a decrease in the packing of the cellulose crystal lattice (increase in d-spacing d200), as well as significant mass losses measured by thermogravimetric analysis and changes in the biochemical composition, i.e. non-cellulosic polysaccharides attributed to the middle lamellae but also to the cell walls. This work, which proposes for the first time an in-situ investigation of the dynamic temperature evolution of the flax cell wall properties, highlights the reversible behaviour of their crystalline structure (i.e. cellulose) and local mechanical properties after cooling to room temperature, even after exposure to high temperatures.

Physico-Chemical Characterization of Green Synthesized Nanomaterials by UV-Visible Spectroscopy

Abstract: Nanomaterials (NMs) particularly synthesized by green routes have attracted researchers and scientists for their multifunctional industrial applications. NMs have not only revolutionized research, but also our daily life because of numerous applications in medical diagnostics, consumer products, and energy-related applications. Their unique properties are directly related to chemical composition, structure, size and shape. There are several characterization techniques used to determine the size, composition, crystalline structure and other physical properties of NMs. Prominent among them are spectroscopic techniques such as UV-Visible, FTIR, EDX; diffraction techniques such as XRD, SAED; microscopic techniques such as SEM, TEM, AFM and others such as Zeta potential measurements. Every technique has its own merit and demerit. This mini review describes the uses of UV-Vis spectroscopy in characterization of NMs.