Sb Samples Research Articles

Improving thermoelectric performance of Nickel substituted ZnSb alloy through carrier engineering and nanostructuring

Zn1-xNixSb (0 ≤ x ≤ 0.08) nanostructures were prepared by the planetary Ball milling technique. XRD analysis confirms the phase purity and orthorhombic crystal structure of the samples. FESEM analysis shows the spherical morphology of the Zn1-xNixSb samples. The EDX and elemental mapping analysis confirms the composition and elemental distribution of Zn1-xNixSb (0 ≤ x ≤ 0.08) alloys. HRTEM images clearly show the interfaced grains with grain boundaries. DRS-UV analysis revealed the narrowing of bandgap while increasing the Ni content in Zn site due to alloying effect. The synthesized Zn1-xNixSb alloys show low resistivity compared to pure samples due to high carrier concentrations. Seebeck coefficient of Zn1-xNixSb alloys were measured from room temperature to 635 K. A high-power factor of 1344 µW/m K2 was obtained for the Zn0.98Ni0.02Sb sample at 533 K compared to pristine ZnSb (574 µW/m K2 at 533 K). High thermoelectric figure of merit (zT) of 0.69 was achieved for Zn0.98Ni0.02Sb sample at 533 K compared to pristine ZnSb (zT of 0.34 at 533 K). The experimental results illustrated that Nickel substitution is a one of the possible ways to improve the thermoelectric figure of merit of ZnSb alloys.

Enhancing upconversion luminescence intensity of BiTa7O19:Er3+/Yb3+/Mo4+ by doping Sc3+ or Sb

AbstractBased on the previous optimal concentration of Er3+/Yb3+/Mo4+ co‐doped BiTa7O19 (BTO) samples, Sc3+ or Sb is planned to be doped into BTO:Er3+/Yb3+/Mo4+ for further improving the upconversion luminescence (UCL) intensity under 980‐nm laser excitation. A series of BTO:Er3+/Yb3+/Mo4+/Sc3+ and BTO:Er3+/Yb3+/Mo4+/Sb samples are prepared by high‐temperature solid‐phase sintering method. The microstructure and UCL properties are investigated by X‐ray diffraction, Raman, X‐ray photoelectron spectroscopy (XPS), diffuse reflection, and luminescence spectrum. The green UCL intensity of BTO:Er3+/Yb3+/Mo4+/Sb is little better than that of BTO:Er3+/Yb3+/Mo4+/Sc3+, which reaches 2.40 times than that of β‐NaYF4:Er3+/Yb3+. XPS results show that Sc is 3+, Mo is 4+, and Sb is 3+ and 5+. Raman spectra show that BTO:Er3+/Yb3+/Mo4+/Sb has lower phonon energy and more disorder than BTO:Er3+/Yb3+/Mo4+/Sc3+. The maximum relative temperature sensitivity is got as 0.01012 K−1 at 303 K based on luminescence intensity ratio technology. BTO:Er3+/Yb3+/Mo4+/Sb has outstanding pure green UCL intensity, which can be applied to luminescence display and temperature sensing.

On-site monitoring of dissolved Sb species in natural waters by an automatic system using flow injection coupled with hydride generation atomic fluorescence spectrometer

Antimony (Sb) is a toxic and potentially carcinogenic element in the environment. The toxicity of Sb(III) is ten times that of Sb(V). Therefore, on-site monitoring technique for dissolved Sb species is crucial for the study of Sb environmental processes. In this study, an automated, portable, and cost-effective system was developed for field simultaneous analysis of Sb(III) and Sb(III + V) in natural waters. The system comprised a portable atomic fluorescence spectrometer equipped with a built-in electrochemical H2 generator to reduce the consumption of acid/borohydride solution and make the atomizer more stable for on-site analysis. Flow injection technique was also used to achieve on-line pretreatment of water samples, including filtration, acidification, pre-reduction, and hydride generation procedures. Under the optimal conditions, the limits of detection (3σ, n = 11) of the developed method were 0.015 μg/L and the linear ranges were 0.05–5.0 μg/L for both Sb(III) and Sb(III + V). The relative standard deviations (n = 11) of the spiked samples of Sb(V) were 3.2% (0.05 μg/L), 3.3% (0.2 μg/L), and 1.7% (0.5 μg/L), respectively. The spiked recoveries of lake water, treated wastewater, and seawater ranged from 97.0% to 108.5%. The novel system of flow injection coupled with hydride generation atomic fluorescence spectrometer (FI-HG-AFS) was applied to carry out an 18-h fixed-point monitoring at a secondary settling tank of a wastewater treatment facility in Xiamen University, and a 6-h real-time underway analysis in the surface seawater of Dongshan Bay, China, proving that the system was capable of long-term monitoring in the field.

Thermoelectric and transport properties of half-Heusler FeNb1-xTixSb alloys

In this work, Ti-doped FeNbSb half-Heusler alloys were synthesized by arc and induction melting techniques. The samples were then thermally treated for 48 h at 923 K in evacuated silica tubes. Powders of the prepared samples were alloyed via ball milling for 2 h in an argon atmosphere at milling speed of 450 rpm to obtain nanocomposites. Crystal structure, elemental distribution and morphological properties were examined throughout the diffraction patterns of X-ray, scanning by the electronic microscope alongside with energy dispersive x-ray spectroscopy. Transport and thermoelectric properties were investigated over a wide temperature range between 300 and 800 K. The electrical conductivity was significantly improved due to the Ti doping which then resulted in remarkable increase in the thermoelectric power factor. The electrical conductivity showed an increase from 46 Ω−1cm−1 to 3000 Ω−1cm−1 with an improvement of 98 %, at room temperature. At high temperature (800 K), The electrical conductivity increased from 150 Ω−1cm−1 to 1414 Ω−1cm−1, upon doping. A maximum power factor of 21 μW cm−1 K−2 for the highest Ti doped sample (FeNb0.8Ti0.2Sb), achieved at 800 K. Alongside improving the electrical conductivity, a remarkable reduction in the lattice and the total thermal conductivity was achieved due to Ti doping, over the whole temperature range. The lattice thermal conductivity exhibited a notable reduction from 12 W/m.K for the pristine FeNbSb alloy to 8.5 W/m.K for the Ti-doped FeNb0.8Ti0.2Sb alloy, at room temperature with a reduction of ∼30 %. The total thermal conductivity of the parent compound decreased from 12.05 W/m.K to 7.4 W/m.K, at room temperature. Accordingly, a promising figure of merit was recorded at around 0.20 for FeNb0.8Ti0.2Sb sample, at 800 K. A notable improvement in the figure of merit, zT with a percentage of ∼ (84–92) % at 800 K is obtained, in comparison to that of the parent FeNbSb alloy, due to Ti doping. ZT is increased from 0.0011, for the parent FeNbSb sample, to 0.05 for the highest-doped FeNb0.8Ti0.2Sb sample, at room temperature. Moreover, it increased from 0.015 for the parent sample to 0.2 for the highest-doped sample, at 800 K.

Shear Bond Strength of Repaired CAD/CAM Resin-Based Composite Materials Submitted to Er:YAG Laser Treatments at Different Powers

This study aimed to investigate the effects of different powers of Er:YAG laser irradiation on the shear bond strength (SBS) of repaired CAD/CAM resin-based composite materials. A total of 180 CAD/CAM resin-based composite specimens (5 × 5 × 2 mm) were obtained (Shofu Block HC—SB; Grandio Blocs—GB). They were allocated into six groups according to surface pretreatment methods: no surface pretreatment (control), hydrofluoric acid (HF), diamond bur and 3 W, 5 W, and 7 W Er:YAG lasers (20 Hz) (n = 15). Silane and universal adhesive were applied. The repair procedure was completed with nano-ceramic composite resin (Ceram-X Sphere TEC-One). The samples were thermocycled for 10,000 cycles (5–55 °C). The SBS was evaluated with a universal test machine (1 mm/min). A 3D optic profilometer was used to assess the surface topography. Statistical analysis was performed with a two-way ANOVA and Bonferroni tests (p < 0.05). For SB samples, HF and diamond bur caused significantly higher SBSs than 3 W and 7 W lasers, while for GB samples, they led to a significantly higher SBS than all laser treatments. For SB samples, the 5 W laser led to the highest SBS, while for GB samples, the 7 W laser caused the highest SBS (p < 0.05). For both blocks, adhesive failure was more common for the 3 W laser, and a decrease in adhesive failures and an increase in mixed failures were observed with increasing laser irradiation. The 3D optic profilometer revealed that smoother surfaces were obtained with the 3 W laser than other laser irradiation at different powers. Pretreatment with increasing Er:YAG laser powers led to similar bond strengths to hydrofluoric-acid- and diamond-bur-treated CAD/CAM resin-based composite materials. A more powerful laser treatment is required to provide a higher bond strength for restorative materials containing a higher inorganic ceramic content.

Structure and thermoelectric properties of half-Heusler-like TiFeCuxSb alloys

Previous research on the ternary Ti-Fe-Sb system has revealed that stoichiometric TiFeSb cannot exist as a stable compound, whereas a single-phase TiFe1.33Sb alloy with the half-Heusler-like structure has been synthesized by adding excessive Fe. In this work, we report that TiFeSb can also be stabilized by filling additional Cu to the vacant 4d site of the half-Heusler lattice. Our experiments indicate that the TiFeCuxSb (x = 0–0.25) samples exhibit a p-type conduction with extremely high carrier concentration ((0.5 –2.5) × 1022 cm−3)), while these samples attain very large Seebeck coefficients, over 100 μV/K in the whole measured temperature range for the samples with x = 0.15–0.25. In addition, a logarithmic divergence of the temperature-dependent specific heat capacity (CP/T) is observed at low temperatures, implying the strange-metal behavior of TiFeCuxSb samples. The partial filling of the vacant 4d site results in significantly reduced lattice thermal conductivity, leading to the low total thermal conductivity of 2.8 W·m−1·K−1 at 823 K for the TiFeCu0.20Sb sample. Consequently, a dimensionless figure of merit zT of 0.54 at 923 K is realized for TiFeCu0.20Sb, demonstrating that promising thermoelectric materials with intriguing physical properties can be discovered in the composition gap of half- and full-Heusler alloys.

Enhanced Thermoelectric Properties of Nb-Doped Ti(FeCoNi)Sb Pseudo-Ternary Half-Heusler Alloys Prepared Using the Microwave Method.

Pseudo-ternary half-Heusler thermoelectric materials, which are formed by filling the B sites of traditional ternary half-Heusler thermoelectric materials of ABX with equal atomic proportions of various elements, have attracted more and more attention due to their lower intrinsic lattice thermal conductivity. High-purity and relatively dense Ti1-xNbx(FeCoNi)Sb (x = 0, 0.01, 0.03, 0.05, 0.07 and 0.1) alloys were prepared via microwave synthesis combined with rapid hot-pressing sintering, and their thermoelectric properties are investigated in this work. The Seebeck coefficient was markedly increased via Nb substitution at Ti sites, which resulted in the optimized power factor of 1.45 μWcm-1K-2 for n-type Ti0.93Nb0.07(FeCoNi)Sb at 750 K. In addition, the lattice thermal conductivity was largely decreased due to the increase in phonon scattering caused by point defects, mass fluctuation and strain fluctuation introduced by Nb-doping. At 750 K, the lattice thermal conductivity of Ti0.97Nb0.03(FeCoNi)Sb is 2.37 Wm-1K-1, which is 55% and 23% lower than that of TiCoSb and Ti(FeCoNi)Sb, respectively. Compared with TiCoSb, the ZT of the Ti1-xNbx(FeCoNi)Sb samples were significantly increased. The average ZT values of the Nb-doped pseudo-ternary half-Heusler samples were dozens of times that of the TiCoSb prepared using the same process.

Interplay between resin cements and surface-treated Poly-Ether-Ether-Ketone (PEEK)

Aim: This study assessed the effect of thermal aging on the interfacial strength of resin cements to surface-treated PEEK. Methods: Ninety-six PEEK blocks were allocated into 4 groups (n=24), according to following surface treatments: SB - sandblasting with aluminum oxide; SA - acid etched with 98% sulfuric acid; CA – coupling agent (Visio.link, Bredent) and CO - control group (untreated). Surface roughness (Ra) was measured and one cylinder (1-mm diameter and height) of Rely-X Ultimate - ULT (3M/ESPE) and another one of Panavia V5 - PAN (Kuraray) were constructed on the treated or untreated PEEK surfaces. Half of the samples of each group were thermal aged (1,000 cycles). Samples were tested at a crosshead speed of 1 mm/min in shear mode (μSBS). Ra and μSBS data were compared using one- and three-way ANOVA, respectively, and Tukey’s tests. Results: SA and SB samples had the roughest surfaces, while CA the smoother (p<0.001). Thermal aging reduced μSBS regardless the surface treatment and resin cement used. There was interaction between surface treatment and resin cement (p <0.001), with ULT showing higher μSBS values than PAN. SA provided higher μSBS than SB for both resin cements, while for CA μSBS was higher (PAN) or lower than SB (ULT). Conclusion: Aging inadvertently reduces interfacial strength between PEEK and the resin cements. If ULT is the resin cement of choice, reliable interfacial strength is reached after any PEEK surface treatment. However, if PAN is going to be used only SA and CA are recommended as PEEK treatment.

Optimization of alkali concentration in the pretreatment of sugarcane bagasse for ethanol production

This study was aimed for the investigation of the effect of pretreatment procedure of alkaline, based on the chemical arrangement, surface morphology, structural composition and enzymatic assimilation of sugarcane bagasse for sugars and ethanol production. Alkali pretreatment (0 to 8% w/v of NaOH) assists to reduce the lignin portion (from 19.57±0.03% to 9.91±0.02%) and increase the cellulose content of the treated SB (from 34.66±0.05% to 63.58±0.05%) simultaneously. The optimal conditions for alkali pretreatment were 8% NaOH charge at 100oC for 90 min. Enzymatic digestibility of alkali treated SB was significantly improved and hydrolysis yield reached to 89.59% glucose and 61.23% xylose at an prime level using Trichoderma viridae. Further hydrolysate of 8% (w/v) alkali treated SB sample was fermented by Saccharomyces cerevisiae to convert sugar into ethanol and yield was 16.81±0.32% in 24 h. Alkali pretreatment was found to be a treatment of choice for cellulose hydrolysis in SB and subsequent sugar acquired for the production of ethanol during fermentation. Bangladesh J. Sci. Ind. Res. 58(2), 89-98, 2023

Influence of the Impurity Element Sb on Oxidation Resistance and Creep Strength of the Ni-Base Single Crystal Superalloy TMS-238

The influence of impurity element Sb on the oxidation resistance and creep strength of the single crystal superalloy TMS-238 was studied in this work. It was found that 1.1 ppm Sb clearly degrades the oxidation resistance, but not for the creep strength. As we increased the amount of Sb up to 3.8 ppm, the weight loss of the sample increased, as expected for the effect of Sb on the oxidation resistance. To understand the mechanism, the oxide structure was characterized by scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS), and three-dimensional atom probe (3DAP) was used to visualize the Sb distribution. 3DAP analysis has revealed Sb segregation of 0.03 at％ to 0.04 at％ at the oxide/substrate interfaces for 3.8 ppm Sb sample. These results indicated that the segregation of Sb, a low melting point metallic impurity, at the oxide/substrate interface degrades the oxidation resistance for TMS-238.

Microbial Reduction of Antimony(V)-Bearing Ferrihydrite by Geobacter sulfurreducens.

The reduction of Sb(V)-bearing ferrihydrite by Geobacter sulfurreducens was studied to determine the fate of the metalloid in Fe-rich systems undergoing redox transformations. Sb(V) added at a range of concentrations adsorbed readily to ferrihydrite, and the loadings had a pronounced impact on the rate and extent of Fe(III) reduction and the products formed. Magnetite dominated at low (0.5 and 1 mol%) Sb(V) concentrations, with crystallite sizes decreasing at higher Sb loadings: 37-, 25-, and 17-nm particles for no-Sb, 0.5% Sb, and 1% Sb samples, respectively. In contrast, goethite was the dominant end product for samples with higher antimony loadings (2 and 5 mol%), with increased goethite grain size in the 5% Sb sample. Inductively coupled mass spectrometry (ICP-MS) analysis confirmed that Sb was not released to solution during the bioreduction process, and X-ray photoelectron spectroscopy (XPS) analyses showed that no Sb(III) was formed throughout the experiments, confirming that the Fe(III)-reducing bacterium Geobacter sulfurreducens cannot reduce Sb(V) enzymatically or via biogenic Fe(II). These findings suggest that Fe (bio)minerals have a potential role in limiting antimony pollution in the environment, even when undergoing redox transformations. IMPORTANCE Antimony is an emerging contaminant that shares chemical characteristics with arsenic. Metal-reducing bacteria (such as Geobacter sulfurreducens) can cause the mobilization of arsenic from Fe(III) minerals under anaerobic conditions, causing widespread contamination of aquifers worldwide. This research explores whether metal-reducing bacteria can drive the mobilization of antimony under similar conditions. In this study, we show that G. sulfurreducens cannot reduce Sb(V) directly or cause Sb release during the bioreduction of the Fe(III) mineral ferrihydrite [although the sorbed Sb(V) did alter the Fe(II) mineral end products formed]. Overall, this study highlights the tight associations between Fe and Sb in environmental systems, suggesting that the microbial reduction of Fe(III)/Sb mineral assemblages may not lead to Sb release (in stark contrast to the mobilization of As in iron-rich systems) and offers potential Fe-based remediation options for Sb-contaminated environments.

Rapid green-assisted synthesis and functionalization of superparamagnetic magnetite nanoparticles using Sumac extract and assessment of their cellular toxicity, uptake, and anti-metastasis property

Modifying the surface properties of superparamagnetic magnetite nanoparticles (SPMNPs) is essential for their stabilization and functionalization in biomedical applications. This study explored the use of Sumac (Rhus coriaria) plant extract as a green stabilizer for SPMNPs. Herein, we fabricated the aqueous colloidal suspension of SPMNPs via a facile and rapid green-assisted co-precipitation method using the extract solution as a green stabilizer (SS), the results were then compared to the uncoated SPMNPs (SB). Physicochemical properties of the as-synthesized NPs were characterized. The XRD planes of both samples matched the typical Fe3O4 NPs with a high degree of crystallinity. FESEM and TEM revealed that SS were spherical and mono-dispersed with an average particle size of 11 nm, while the average particle size of SB was measured to be around 9.9 nm. The elemental compositions of the SS were approved by the EDX technique. FTIR and TGA results confirmed the presence of functional groups in the extract components and their interactions with SPMNPs. Based on the DLS analysis, Sumac extracts significantly prolonged the stability and increased the zeta potential value of the SPMNPs nanofluid from −28.2 to −44.8 mV. The magnetization (Ms) values of SB and SS samples were found to be 62.95 emu/g and 139.56 emu/g, respectively. VSM results pointed out that Sumac extracts dramatically enhanced the saturation magnetization of the coated SPMNPs. In vitro cytotoxicity and scratch assays of the SS against MCF-7 cells indicated the non-toxicity, proliferation modulation, and growth inhibition abilities (anti-metastatic properties) of the modified NPs. In addition, the cellular uptake assessment of SS on the MCF-7 cancer cell line revealed a dose-dependent internalization. Our findings implied that this hydrophilic, highly magnetic, stable, and biocompatible SS is probably capable of being used in a wide range of biomedical applications such as MRI, magnetic hyperthermia, and cancer treatment.

Enhancement of thermoelectric properties at room temperature through isoelectronic ruthenium-substitution in [formula omitted]-type half-Heusler VFeSb compounds

The effects of ruthenium (Ru) substitution on the thermoelectric properties of half-Heusler (HH) V(Fe1−xRux)Sb compounds have been theoretically and experimentally investigated. All V(Fe1−xRux)Sb samples with deficient HH structures reveal deficiencies in V 4a and Fe 4c sites, interstitial Fe occupied 4d sites, and Ru substituted for Fe 4c sites, by Rietveld analysis. Based on the refined crystal structures and electronic structure analysis, the Ru content x with a maximum power factor (PF) is predicted to be around x=0.02. A small amount of Ru-substitution improves the PF by 26% at room temperature for the V(Fe0.98Ru0.02)Sb sample, which is coincident with the predicted range of Ru content for maximum PF. The lattice thermal conductivity κL of the V(Fe1−xRux)Sb samples decreases with an increase in x. The atomic mass and radius of Ru are substantially larger than those of Fe; therefore, κL of the V(Fe1−xRux)Sb samples decreases mainly due to phonon scattering strengthened by the introduction of Ru at the Fe 4c sites. A significantly reduced κL of 5.8 W/Km at room temperature is obtained for the V(Fe0.92Ru0.08)Sb sample, which is a ca. 40% decrease compared with the pristine HH-VFeSb sample. The dimensionless thermoelectric figure-of-merit reaches close to 0.2 at 300 K for the V(Fe0.98Ru0.02)Sb sample.

Designing vacancy-filled Heusler thermoelectric semiconductors by the Slater-Pauling rule

Heusler alloys with six valence electrons per atom on average are Slater-Pauling semiconductors. The half-Heusler semiconductor exhibits excellent thermoelectric properties due to its specific electronic band structure. In this work, we report on the design and discovery of HfRu1+xSb-based semiconductors using the Slater-Pauling rule. According to the Slater-Pauling rule, the composition HfRu1.5Sb with 21 valence electrons is a stable semiconductor, agreeing well with our theoretical calculation. Experiments reveal that the HfRu1.6Sb sample is nearly an intrinsic semiconductor, which deviates slightly from the Slater-Pauling rule and theoretical calculation. Meanwhile, both p-type (x < 0.6) and n-type (x > 0.6) conductions can be realized in the HfRu1+xSb samples by adjusting the Ru content, and the thermoelectric properties of the HfRu1+xSb samples can be further improved by isoelectronic alloying on the Hf site with Ti. The dimensionless thermoelectric figure of merit zT of p-type HfRu1.4Sb semiconductor is ∼0.37 at 973 K, and the Ti0.9Hf0.1Ru1.4Sb sample reaches a zT value about 0.50 at 973 K, achieving an increase of 30%. Our work shows that more vacancy-filled Heusler semiconductors with tunable and promising thermoelectric properties could be designed based on the Slater-Pauling rule.

Discovery of a Slater–Pauling Semiconductor ZrRu1.5Sb with Promising Thermoelectric Properties

AbstractCubic half‐ and full‐Heusler compounds with respectively 18 and 24 valence electrons exhibit semiconducting behaviors according to the Slater–Pauling rule. In this work, a half‐Heusler‐like ZrRu1.5Sb semiconductor with the space group F3m is discovered based on the Slater–Pauling rule. The ZrRu1.5Sb compound has 21 valence electrons per chemical formula and each atom has six valence electrons on average, showing a p‐type conduction with a dimensionless thermoelectric figure of merit zT ≈0.2 at 973 K. By adjusting the Ru content, both p‐type (x ≤ 0.5) and n‐type (x &gt; 0.5) semiconductors are realized in the ZrRu1+xSb solid solution. Following this way, other half‐Heusler‐like semiconductors, such as ZrRu1.30Ni0.10Sb, ZrRu1.40Ni0.05Sb, and ZrRu1.30Ni0.05Sb, are also successfully designed and synthesized, demonstrating the effectiveness and practicality of our strategy to explore Slater–Pauling semiconductors. Furthermore, these half‐Heusler‐like semiconductors show promising potential as thermoelectric materials. The p‐type ZrRu1.4Sb and n‐type ZrRu1.7Sb samples have zT values of 0.38 at 973 K and 0.25 at 773 K, respectively, offering superior base materials for further optimizing their thermoelectric properties. The discovery of ZrRu1.5Sb‐based thermoelectric semiconductors demonstrates the great potential to design Slater–Pauling phases with exotic physical properties.

Reclaim and Valorization of Sea Buckthorn (Hippophae rhamnoides) By-Product: Antioxidant Activity and Chemical Characterization.

The by-product resulting from the production of the sea-buckthorn (Hippophae rhamnoides) juice may be a functional food ingredient, being a valuable source of bioactive compounds, such as polyphenols, flavonoids, minerals, and fatty acids. For checking this hypothesis, two extracts were obtained by two different methods using 50% ethyl alcohol solvent, namely through maceration–recirculation (E-SBM) and through ultrasound extraction (E-SBUS), followed by concentration. Next, sea-buckthorn waste (SB sample), extracts (E-SBM and E-SBUS samples) and the residues obtained from the extractions (R-SBM and R-SBUS samples) were characterized for the total polyphenols, flavonoid content, antioxidant capacity, mineral contents, and fatty acids profile. The results show that polyphenols and flavonoids were extracted better by the ultrasound process than the other methods. Additionally, the antioxidant activity of the E-SBUS sample was 91% higher (expressed in Trolox equivalents) and approximately 45% higher (expressed in Fe2+ equivalents) than that of the E-SBM sample. Regarding the extraction of minerals, it was found that both concentrated extracts had almost 25% of the RDI value of K and Mg, and also that the content of Zn, Mn, and Fe is significant. Additionally, it was found that the residues (R-SBM and R-SBUS) contain important quantities of Zn, Cu, Mn, Ca, and Fe. The general conclusion is that using the ultrasound extraction method, followed by a process of concentrating the extract, a superior recovery of sea-buckthorn by-product resulting from the juice extraction can be achieved.

An Experimental Study on the Stabilization of Bentonite Treated with a Composite Reinforcement Made of Sand and an Ionic Soil Stabilizer

As an ionic soil stabilizer (ISS) can effectively reduce the expansive properties of bentonite and sand can improve the strength of a soil rapidly thereby reducing the likelihood of cracks, in the present study, these two methods are combined to strengthen bentonite. Different experiments are carried out and the results confirm that the proposed strategy can effectively be used to improve the properties of this material. It is also shown that the sand-to-bentonite mass ratio has different effects on the unconfined compressive strength (UCS) of the SB (sand strengthened) and ISB (ISS-sand composite strengthened bentonite) samples. The UCS of these two samples both attenuates significantly after one freeze-thaw cycle and then display only minor changes after multiple cycles.

COMPARATIVE STUDY OF Sida rhombifolia FROM TWO DIFFERENT LOCATIONS

Sida rhombifolia or sidaguri, was taken from two regions in East Java Province, Indonesia, namely Batu (SB) and Ngawi (SN), was investigated in this study. The two samples were determined the content of secondary metabolites by using LC-MS/MS. They were also evaluated for their phytochemical content, total phenolic content (TPC), and antioxidants activity, using the DPPH and ABTS methods. The highest TPC (126.93 ± 0.63 mg GAE / g) was observed in the ethyl acetate fraction of SN. The antioxidant activity against DPPH and ABTS from crude extracts and fractions showed that SB was more potent than SN, although the values were both less active. A total of 54 secondary metabolites were identified by the LC-MS-MS method from both species, with SB samples producing more secondary metabolites (48 compounds) than SN (37 compounds). These compounds are included in lipids, alkaloids, ester lactones, benzoic acid derivatives, steroids, carboxylic acid derivatives, flavonoids, and phenyl propanoic.

Influence of the synthesis parameters on the transport properties of Mg2Si0.4Sn0.6 solid solutions produced by melting and spark plasma sintering

In this work, the influence of the preparation route on the structural, morphological, and thermoelectric properties of the Mg2Si0.4Sn0.6 solid solutions is investigated. The synthesis based on melting the constituent elements in a closed graphite crucible followed by spark plasma sintering allows mixing elements with a large difference of their melting temperatures and a good control of sample stoichiometry. The optimized synthesis route is validated by the doped V and Sb samples, which yield good thermoelectric performance. The n-type doping leads to two orders of magnitude increase of the carrier concentration, and thus a subsequent increase of the electrical conductivity, which, in turn, augments greatly the power factor of the Mg1.98V0.02Si0.385Sn0.6Sb0.015 to 42.61 x10−4 Wm−1K−2 at 650K. Although doping slightly enlarges the thermal conductivity, a peak value of the figure of merit ZT∼1.15 is obtained at 723K, which is 20 times higher than the ZT of un-doped material.

Experimental characterization of Mode II fatigue delamination growth onset in composite Joints

In this article, the structural behavior of co-cured composite joint (CC), co-bonded composite joint (CB), and secondary-bonded composite joint (SB) under Mode II fatigue loading was evaluated. Fatigue performance was evaluated in sub-critical strain energy release rate (SERR) associated with Mode II fatigue induced delamination growth onset. Fatigue tests were carried out using the three-point bending End Notched Flexure test setup for different energy ratios. The experimental results are presented in terms of SERR versus number of cycles, and the SERR threshold for no growth is determined (Gth). Fractographic analyses were performed in order to identify the main failure mechanisms related to each joining technology under Mode II. The results indicated an initial cohesive failure followed by an adhesive failure promoted by crack propagation at the interface between the adhesive and the composite adherend on SB and CB samples, through the coalescence of microcracks that promote the adhesive failure process, leading to fiber pull-out from the matrix and cusps formation in the fracture surface. These results explain the low performance behavior observed on SB and CB bonded techniques. It is worth mentioning that the results and behavior observed in this work are valid only for the laminates, adhesives, surface treatment, and environmental conditions tested herein.