Ti Values Research Articles

Effect of AP coating or blending on the ignition and combustion of Al particles under a high-pressure water vapour–Ar environment

Overcoming the difficulty of ignition and combustion of aluminium in water vapour is the key to being applied in underwater propellant applications. The effect of coating or blending 20 mass% ammonium perchlorate (namely, AP@Al or AP–Al samples) on the ignition and combustion of Al particles in a 1.0 MPa water vapour–Ar environment was investigated using a constant temperature pressurized combustion chamber and a CO2 laser. The results show that the combustion of Al particles in a water vapour–Ar environment is a non-homogeneous reaction and that agglomeration processes of Al droplets are observed. The ignition and combustion properties of the AP@Al and AP–Al samples under water vapour were greatly improved due to the decomposition of AP for heat/oxygen (particularly, O2 provided a new pathway for AlO(g) generation) supply and the effect of dispersed particles. The maximum pressure change and combustion temperature (Tmax) were increased significantly for the AP@Al and AP–Al samples combustion, while their ignition delay time (ti) and combustion time (tc) decreased remarkably. In addition, the coating form is more effective in the combustion-promoting effect of AP than the blending form. Interestingly, the increase in water vapour concentration is not conducive to the ignition and combustion of samples in this work. It is probably because the reaction system is lean-fuel where the excess water vapour absorbs some of the heat and prevents effective collisions among the radicals. In addition, the chemical equilibrium largely influences the combustion temperature, resulting in a conspicuous effect of changes in water vapour concentration on the Tmax values. The reaction interface largely influences the combustion reaction rate of Al, so changes in particle size have a significant effect on the ti and tc values.

Trace elements and growth patterns in quartz from the Alubaogeshan granite in the Maodeng Mo-Bi-Sn-Cu deposit, southern Great Xing’an Range, NE China

The Maodeng Mo-Bi-Sn-Cu deposit is located in the southern segment of the Great Xing’an Range in northeastern China. The Alubaogeshan complex is the major intrusion in this region, which is composed of porphyritic monzogranite (PMG), granite porphyry (GP), and alkali feldspar granite (AFG). We conducted SEM-CL and LA-ICP-MS analyses to examine internal textures and trace elements of quartz from three facies, aiming to uncover the petrogenetic connections among the different lithologies. Quartz phenocrysts from PMG and GP exhibit smudged pre-resorption core, and post-resorption quartz overgrowths with higher Ti concentration and CL intensity, whereas quartz from AFG shows a taxitic structure, with an outward decrease in Ti concentration and CL intensity. There is a positive correlation between CL intensity and Ti content in magmatic quartz. The Al/Ti and Ge/Ti ratios in quartz indicate that the degrees of differentiation of PMG and GP are comparable and relatively low, while that of AFG is high. Trace element contents also exhibit characteristic evolution during magmatic differentiation, with the higher Al, Be, Ge, Rb, and B, and the lower Ti contents in quartz from the highly evolved AFG, and the higher Ti values in quartz from the less evolved PMG. A strong correlation between Al and Li concentrations suggests that Li+ is a primary charge compensator of Al3+ substituting for Si4+ in quartz, with the remaining Al3+ equilibrating with H+. The entry of Al into quartz is mainly controlled by crystallization temperature in the less evolved granite, but magmatic differentiation exerts a key role in the highly evolved granite. Magma differentiation is a primary factor influencing Ge incorporation into quartz. Quartz crystals from PMG and GP display textural and chemical evidence of high-Ti, -CL, and -temperature overgrowth, indicating multiple recharges of mafic magma into the felsic magma chamber. This process could have supplied abundant metals to the granitic magma system and contributed to the formation of the Maodeng deposit.

Model Simulation and Rheological Research on Crosslinking Behavior of Polyethylene Resin.

The crosslinking behavior of polyethylene (PE) determines its exceptional performance and application. In this study, we investigated the crosslinking behaviors of different PE resins through model simulation and rheological methods. Specifically, the mathematical equation of "S" model was established for PE resin. According to this equation, the optimal maximum gel content for high-density polyethylene (HDPE) was found to be around 85%. Moreover, the maximum crosslinking degrees for different PE resins depended largely on their density and molecular weight. The melt viscosities before crosslinking in PE resins were highly influenced by their melt index. The higher melt indexes resulted in the lower storage moduli, improving melt processability during processing. In addition, the crosslinking rates of PE resins were strongly influenced by peroxide concentration, independent of PE resin structures. For high molecular weight and low-density PE resins, they exhibited decreased ti values, increased A0 values, and decreased k6 values. However, there were no noticeable variations in the values of k2 and phi among different PE resins. All simulated modeling outcomes showed remarkable consistency with the experimental rheological data. These findings are of strong significance in the industrial manufacture of PE resin.

Geochronology and Geochemistry of Volcanic and Intrusive Rocks from the Beizhan Iron Deposit, Western Xinjiang, NW China: Petrogenesis and Tectonic Implications

The Awulale Iron Metallogenic Belt (AIMB) located in Central Tianshan is a significant iron ore belt in China. The Beizhan area exhibits extensive volcanic and intrusive rocks that formed during or close to the iron mineralization period. The iron ores in Beizhan are found in Early Carboniferous rhyolite and dacite tuff. The rhyolite is enriched in LILEs and LREEs, depleted in HFSEs, and shows high positive εNd(t) values (+3.0–+4.0). Late Carboniferous intrusive rocks include a granite stock and diabase and diorite dykes. The zircon grains from the granite yield a weighted mean 206Pb/238U age of 311.8 ± 2.6 Ma. The geochemical features of the granite are similar to those of rhyolite, but with pronounced negative anomalies of Eu, Sr, P, and Ti and higher positive εNd(t) values (+4.9–+5.1). The zircons in the diorite dyke yield a weighted mean 206Pb/238U age of 299.2 ± 1.4 Ma. Both the diabase and diorite dykes show an enrichment of LREEs and depletion of HFSEs with high positive εNd(t) values (+3.3–+7.3 and +2.3–+2.6, respectively), although the Eu, Th, and Sr anomalies are more negative in the diorite compared to the diabase. The rhyolite displays high positive εNd(t) values and young Nd model ages (TDM2 = 760–838 Ma) and has Nb/Ta ratios (11.3–12.8) close to that of the continental crust, indicating that it originated from the partial melting of the juvenile lower crust. The granite has similar geochemical characteristics (TDM2 = 656–673 Ma and Nb/Ta ratio = 8.7–10.9) and is also believed to have originated mainly from the partial melting of the juvenile lower crust. The diabase and diorite dykes have low (Tb/Yb)N ratios (<2) and high Ba/Th (31.8–353.2 and 185.3–251.3, respectively) and Sr/Th (113.8–312.9 and 144.7–163.1) ratios, and exhibit a pronounced depletion of HREEs and Y and negative Th anomalies, suggesting that they originated from a spinel-garnet lherzolite mantle source. The Early Carboniferous rhyolite erupted in a continental arc setting, whereas the Late Carboniferous granites, diabase dykes, and diorite dykes formed in an extensional setting associated with the upwelling of the asthenosphere. Therefore, the magmatism and Fe mineralization in the AIMB are correlated with an extensional setting associated with oceanic slab breakoff.

Dental Implant Corrosion Products May Accumulate in the Human Body

Corrosion products resulting from the degradation of the dental implant surface due to biological fluids and infection may accumulate in the body and lead to clinical consequences. The primary aim of this study is to measure the accumulation of dental implant corrosion products in the human body and the secondary aim is to estimate the association between corrosion products and fatigue. This study was designed as a prospective cross-sectional and was conducted with patients presenting at to the Department of Oral and Maxillofacial Surgery. The study included patients with Grade IV dental implants made of pure titanium (Ti) at the bone level and Grade V abutments composed of Ti, aluminum (Al), and vanadium (V). Individuals possessing different metallic implants and those prone to metal exposure were not included in the study. Blood and hair samples were procured from each participant and subsequently analyzed. The predictor variable is implant exposure, and it was divided into 3 groups; Group I, patients with healthy dental implants; Group II, patients with peri-implantitis; Control Group, individuals without dental implants. The primary outcome variables are Al, Ti, V levels in blood and hair samples and the secondary outcome variable is the fatigue questionnaire score. Age and gender, along with the dental implant number and duration of exposure within the study groups, are utilized as covariates. Groups were compared using the Kruskal-Wallis and Mann-Whitney U-tests. Spearman's correlation coefficient determined relationships between groups, signifying significance with P values<.05. The sample consisted of 30 patients aged 18 to 68, with 53% being female and 47% male. The differences among the 3 groups in the median values of blood Ti, V; hair Al, Ti, V; and fatigue questionnaire scores were not statistically significant (P>.05). However, the median blood Al value was statistically higher in Group II (P<.05). While the presence of healthy dental implants may not affect the accumulation of Al, Ti, and V within the body, patients with peri-implantitis exhibited elevated blood Al levels, possibly due to infection influencing the corrosion process.

From divergent to convergent plate boundary: A ca. 200 Ma Wilson cycle recorded by ultrahigh-pressure eclogites in the Dora-Maira Massif, Western Alps

Sparse eclogite exposure in accretionary-to-collisional orogens cannot only reveal the sites of ancient subduction zones and plate boundaries, but also elucidate the multi-stage tectonic evolution in the Wilson cycle. The southern part of the Dora-Maira Massif in the Western Alps is well known for its ultrahigh-pressure (UHP) rocks and contains small occurrences of petrographically distinct types of eclogite. Due to the lack of detailed geochronological and geochemical data on these rocks, the nature of their protolith and related geodynamic setting has remained unknown. In the current study, 33 samples from 13 localities were studied by whole-rock major- and trace-element analysis, and a selection of the samples were studied using Sr-Nd-Hf isotopes, as well as high-resolution elemental mapping and U-Pb geochronology of zircon. According to macroscopic appearance, petrography, chemical composition, and principal-component analysis of multi-elements, two major types are distinguished. Light-colored eclogite is phengite-rich, commonly foliated, bears kyanite and quartz/coesite, shows relatively high MgO, K2O, SiO2, εNd(t) (−2.2 to +1.4), and εHf(t) (+3.5 to +7), with a protolith geochemically similar to an enriched-type mid-oceanic-ridge basalt (E-MORB). Dark eclogite generally is massive, rutile-rich, shows higher values of Ti, Fe, P, Nb, and Zr, εNd(t) values between −2.8 and −0.8, εHf(t) values between −6.1 and −3.2, with an oceanic island basalt (OIB)-type protolith composition. Magmatic zircon cores, which are characterized by steep heavy rare earth element (HREE) patterns and negative Eu anomalies, yield consistent protolith ages of ca. 253−252 Ma in both eclogite types. Metamorphic zircon domains with flat HREE patterns and insignificant Eu anomalies yield a younger mean age of ca. 34 Ma, which is the age commonly assigned to eclogite-facies UHP metamorphism. Considering the various geochemical signatures of E-MORB- to OIB-like eclogites and the regional tectonic evolution, their protolith is best explained as rocks, which crystallized from rift-related basaltic magma, associated with the break-up of the Pangea Supercontinent that eventually resulted in the birth of the Piemonte-Liguria Ocean (Alpine Tethys Ocean) between the future Eurasia and Adria plates. Therefore, the UHP eclogites in the Dora-Maira Massif likely fingerprint a multi-stage tectonic evolution from divergent (continental extension, rifting) to convergent (subduction zone) plate boundary, corresponding to the beginning and end of a Wilson cycle. Incidentally, they reveal that mafic rocks in the Alpine basement units may not be polymetamorphic, but may actually consist of post-Variscan products that underwent only Alpine metamorphism.

The effects of Fe and Al on the phase transformations and mechanical behavior of β-Ti alloy Ti-11at.%Cr

Alloy composition is important for developing desired microstructures in beta-titanium (β-Ti) alloys during thermomechanical processing. In this work, the relatively low-cost alloying elements iron (Fe) and aluminum (Al) were added to a base Ti-11at.%chromium (Cr) alloy and in-situ and ex-situ examination of the microstructural evolution and mechanical properties during tension, hardness, elevated temperature X-ray diffraction (XRD) and resonance ultrasound spectroscopy (RUS) were performed. The 400 °C XRD revealed that Ti-11at.%Cr underwent β-to-ω and β-to-α transformations. Adding 0.85 at.% Fe reduced the volume fraction of the ω- and α-phases, and adding 5.3 at.% Al inhibited the β-to-ω transformation. The 400 °C RUS showed that the alloys containing the ω phase exhibited an increase in shear modulus of ∼140%, while the ω-free alloys exhibited an increase of only ∼102%. The hardness and strength values of the ω-containing Ti–11Cr and Ti–11Cr-0.85Fe increased with increased ω-phase volume fraction when the ω/α ratio was greater than 0.25. The relationship between ω/α volume fraction ratio and mechanical properties is discussed.

Thermal Effects of 445nm Diode Laser-Irradiation on Titanium and Ceramic Implants.

Purpose This study aimed to evaluate temperature changes in titanium and ceramic implants after using a 445nm-diode laser under different in-vitro conditions. Methods A titanium (Ti) and ceramic (Zr) dental implant were placed into a bone analog, and an intra-bony defect was created at each implant. A 445nm-diode laser was used to irradiate the defects for 30 seconds, non-contact, at 2W in continuous wave (c.w.) and pulsed mode. The experiment was done at room temperature (21.0°C±1) and in a water bath (37.0°C±1). Two thermocouple probes were used to record real-time temperature changes (°C) at the coronal part of the implant (Tc) and the apex (Ta). The temperature was recorded at time 0s (To) and after 30s of irradiation (Tf). The average temperature change was calculated, and a descriptive analysis was conducted (p<0.05). Results The Ti implant resulted in the highest ∆T values coronally (29.6°C) and apically (6.7°C) using continuous wave at 21°C. The Zr implant increased to 26.4°C coronally and 5.2°C apically. In the water bath, the coronal portion of the Ti and Zr implants rose to 14.2°C and 14.01°C, respectively, using continuous waves. The ∆T values for Ti were 11.9°C coronally and 1.7°C apically when placed in a water bath using pulsed mode. The lowest ∆T occurred on the Zr implant with ∆Tc and ∆Ta, 4.8°C and 0.78°C, respectively. Conclusion Under in-vitro conditions, the 445nm-diode laser in pulsed mode seems to be safe for use on ceramic implants and should be used with caution on titanium implants.

Adaptive physio-anatomical modulations and ionomics of Volkameria inermis L. in response to NaCl

This study illustrates the salinity tolerance mechanisms in Volkameria inermis (a mangrove-associate), making it an ideal candidate for establishment in saline lands. The plant was exposed to 100, 200, 300, and 400 mM NaCl and the TI value indicates that the stress-imparting concentration was 400 mM. There was a decrease in biomass and tissue water, and a gradual increase in osmolytes like soluble sugars, proline, and free amino acids content was observed in plantlets with the increase in NaCl concentrations. Higher number of lignified cells in the vascular region of the plantlet’s leaves treated with NaCl (400 mM) may influence the transport through the conducting tissues. SEM data reveals the presence of thick-walled xylem elements, an increased number of trichomes, and partially/fully closed stomata in the 400 mM NaCl-treated samples of V. inermis. In general, macro and micronutrient distribution tend to be affected in the NaCl-treated plantlets. However, Na content increased remarkably in plantlets treated with NaCl, and the highest accumulation was observed in roots (5.58-fold). Volkameria inermis can be a good option for phytodesalination in salt-affected areas since it is equipped with strong NaCl tolerance strategies and can be exploited for desalinization purpose of salt affected lands.

First Occurrence of Titanian Hydroxylclinohumite in Marble-Hosting Gem Spinel Deposits, Luc Yen, Vietnam

In this paper, we report the very first occurrence of titanian hydroxylclinohumite in the marble-hosted gem spinel deposits of the Luc Yen district, northern Vietnam. Hydroxylclinohumite is anhedral and associated with forsterite, tremolite, pargasite, diopside, spinel, dolomite and calcite. Hydroxylclinohumite from the Luc Yen deposit was characterized via electron microprobe analysis, single-crystal X-ray diffraction study, and Raman spectrometry. The average composition is (Mg0.69Ti0.29Fe0.02)Σ1.00Mg7.91(SiO4)4.08[(OH)1.10F0.53O0.37]Σ2.00. (ideally (Mg0.7Ti0.3)Σ1Mg8.0(SiO4)4[(OH)1.2F0.5O0.3]2). The compositions of the analyzed hydroxylclinohumites have a narrow range of Mg/(Mg+Fe+Ti) values (0.96–0.97) and a defined hydroxylclinohumite solid-solution series. Compared with other occurrences, the Luc Yen hydroxylclinohumite has an average titanium content, which attains 0.31 atoms per formula unit (3.93 wt.% TiO2) and a low iron content of 0.04 atoms per formula unit (0.42 wt.% FeO). The formation of hydroxylclinohumite is favored by the proportion of Mg, and Si in the precursor rocks and the increased activity of H2O in the fluid phase.

Lake-wide assessment of trace elements in surface sediments and water of Lake Sevan

Lake Sevan (Armenia) is one of the large freshwater high-mountain lakes of Eurasia. Detailed information about the extent and fate of trace elements on lake sediment and water quality has not been published yet. For this reason, surface sediment and water samples were collected from the southern and northern basins of Lake Sevan to determine trace element concentrations and assess the trace element behaviour. Geo-accumulation index, potential ecological risk index, and hazard index were calculated to estimate the environmental risk potential. In comparison to reference values, the investigated sediment samples contained elevated concentrations frequently for V, Cr, Co, Ni, Mo, Cd, Be, Ti, Rb, Sr, Se, Hf, and Th and occasionally for Cu, As, Li, B, Ag, Sb, Tl, Bi, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm. An overall potential ecological risk posed by all the investigated trace elements in the sediments was assessed to be moderate-considerable, however, Mo, Hg, and Cd were the elements with the highest ecological risk potential. The two basins of the lake showed significantly different behaviour according to the investigated trace element contents in the sediments to be higher in the bigger basin compared to the smaller basin. In comparison to reference concentrations in water samples according to the use of the adapted geo-accumulation index, elevated values for Ti, Cr, Cu, Cd, and Pb were observed. Elevated concentration was also observed in the case of B in nearly all water samples in comparison with literature values. Nevertheless, several water samples can be seen as not strongly anthropogenic influenced by Co, Ni, Sn, Sb, Ag, Hg, and Bi. The concentrations of trace elements in the lake water caused health risks to humans particularly children in the case of lake water used for drinking purposes, moreover, As was the main element posing health hazards. The results point out further attention to the sources of elevated trace elements in Lake Sevan, including anthropogenic influences and geological characteristics.

In situ design of ultrafine-grained 7075 Al alloy with laser powder bed fusion

Laser powder bed fusion (L-PBF) is an advanced fast prototyping method for fabricating high-performance metallic components with complex structures. However, the development of L-PBFed high-strength Al alloys is often limited by the hot cracks. To grapple with this difficult issue, a novel solution was proposed by introducing 3 wt% Ti2AlNb intermetallic (IMC) powders into the 7075 Al powders to form an in-situ nucleated 7075 (IN-7075) Al alloy. The results indicated that the as-printed IN-7075 Al alloy was crack-free, and the grain size has been refined from 72.6 μm to 1.5 μm, which was attributed to the in-situ formation of Al3(Ti, Nb) particles and the high grain growth restriction factor (Q) values of Ti and Nb elements in the Al matrix. After a suitable heat treatment, the IN-7075 Al alloy exhibited good mechanical properties with an ultimate tensile strength of 429 ± 2 MPa and an elongation of 9.8 ± 0.5%.

Synthesis and characterization of eco‐friendly poly(ε‐caprolactone) plasticizer facilitating phthalate‐free polyvinyl chloride with novel star/net‐shaped structures

AbstractPotential migration and toxicity limited applications of traditional plasticizers like bis(2‐ethylhexyl) phthalate (DEHP) in food packing and medical machinery and so forth. Safe and feasible bio‐based plasticizers have recently moved into the limelight of research hotspot. Here, we designed series polyester plasticizers of various branches with star‐shaped poly(ε‐caprolactone) (SPCLs) and net‐shaped poly(ε‐caprolactone) (NPCLs) structures by one‐pot solvent‐free synthesis with glycidol and polyglycerol as initiators. Structures of SPCLs and NPCLs were further verified by FTIR, 1H NMR, and 13C NMR. Moreover, the properties of the plasticizers and plasticized PVC were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and tensile test. PVC films plasticized with the SPCLs or NPCLs exhibited increased plasticizing effect, compatibility, flexibility and cold resistance. The lowest Tg value of plasticized PVC samples (PVC/NPCL1‐C4) was −45.3°C, which made the plasticization efficiency reach 122.5%. In particular, PVC/SPCLs‐C4 (SPCL2‐C4) had 107% higher elongation at break than PVC/DEHP. Meanwhile, the initial decomposition temperature Ti value of the PVC blends maximum increased from 240 to 328°C when DEHP was completely replaced by SPCLs or NPCLs, indicating improved thermal stability of the plasticizer. Overall, “green” plasticizers with fining topological branch design would be promising to partially replace petroleum‐based plasticizers.

Investigation of a novel alkali baking–leaching process for dissolution of Fe, Al, Ti, Sc, and Ga values and generation of alumina and titania from red mud

The current study investigates alkali baking using sodium hydroxide followed by water and sulfuric acid leaching to extract Al, Fe, Ti, Sc, and Ga values. Water leaching of baked mass selectively dissolves Al. Subsequent, sulfuric acid leaching of water-leach residue dissolves Fe, Ti, Sc, Ga, and remaining Al and Si values. The alkali baking forms sodium metal oxide (NaFeO2, Na2TiO3, NaAlO2, NaAlSiO4) phases, which improves the dissolution in sulfuric acid compared to the oxide phases of metals. The alkali dose was a prominent factor in forming sodium metal oxides. Baking at 600 °C, 1 h, 75 wt% NaOH yielded 60% Al dissolution during water leaching and 82% Ti, 83% Fe, 97% Sc, and 64% Ga dissolution during acid leaching. Scandium dissolution strongly correlates with titanium during leaching, and TEM analysis confirms the apparent enrichment of scandium in the anatase and hematite matrix. Carbonation of water leach solution precipitates alumina and dawsonite (NaAlCO3(OH)2) phases with a product having 85–87% Al2O3 purity and 12 wt% yield. Thermal hydrolysis of acid leach solution generates Ti(OH)4 precipitate which is calcined to obtain anatase with a 95–97% TiO2 and 13 wt% yield. The leach residue contains unreacted hematite and anatase phases having <10% Al2O3 and SiO2 with 6.5 wt% yield. The hydrolyzed solution contains Sc(III) (6 mg/L), Ga(III) (5 mg/L), and Fe(II) (28.4 g/L) ions. The proposed process consumes 0.75 kg NaOH and 1.40 kg H2SO4 per kg red mud and generates 0.14 kg alumina and 0.13 kg titania product with 0.07 kg residue enriched with 48% anatase.

Effect of poly (acrylamide-co-acrylic acid salt) on anti-aging properties and adhesion between acrylonitrile butadiene rubber and polyester fabric

In this study, a multifunction polymeric adhesion promoter and anti-aging compound based on the triethanolamine salt of acrylamide acrylic acid copolymer (COS) was prepared and characterized using Fourier-transform infrared spectroscopy (FTIR). The impact of different COS contents on the tensile, adhesion, and thermal properties of NBR composite and NBR/PET sandwich was evaluated. The NBR composites containing COS displayed good retention of their mechanical properties with increasing thermal ageing time, while the composite without COS showed a decrease in its mechanical properties. The highest tensile strength (17.5 MPa with a retention value of 0.6%) after 7 days of thermal aging was recorded for NBR composite, which contains 5 phr (parts per hundred parts of rubber) of COS (COS 5), compared to NBR composite without COS (COS 0), which recorded 15.1 MPa with a retention value of -27.4%. In addition, the COS 5 composite displayed an improvement in peel strength of 16.4% compared to the COS 0. The results of the thermogarvemetric analysis (TGA) supported the anti-thermal ageing effect of COS, where the initial decomposition temperature (Ti) value increased by 11.7 and 9.3 °C, after addition of 5 and 10 phr of COS to NBR composite, respectively. In addition, the other thermogravemetric parameters investigated displayed a significant increase in their values, which confirms the improvement in thermal stability of NBR composite in the presence of COS. Also, the air permeability of the PET/NBR sandwich decreased by 80% after the addition of 7.5 phr of COS.

Geochemistry of a paleo-oxbow lake sediments and its implications for the late Holocene extreme overbank flooding history of the Yellow River within the Zoige Basin, NE Tibetan Plateau

Paleo-oxbow lake sediments can provide archives to reconstruct paleo-channel evolution and flooding history of the river. Multi-proxy approaches including detailed sediment stratigraphy, sedimentology and geochemistry have been implemented in a high-resolution sedimentary section of paleo-oxbow lake of the Yellow River within the Zoige Basin on the NE Tibetan Plateau, to reconstruct regional environmental changes and extreme overbank flooding history. Our results suggest that not only traditional sedimentological proxies, but also chemical elements can be applied in defining sequences with different genetic types, especially the paleoflood deposits in the paleo-oxbow profile. Two units of late-Holocence extreme overbank flooding deposits (OFDs) are identified in terms of the significantly higher proportions of sand, high contents of SiO2, Na2O, Ba, low contents of Al2O3, Fe2O3, MgO, K2O, Ti, Rb and high values of Zr/Fe, Zr/Rb ratios. These extraordinary flood events within the Zoige Basin were dated back to 2,960 ± 240–2,870 ± 270 a and 1840 ± 200–1700 ± 160 a, in response to the mid-Holocene climatic optimum to the late Holocene and the Dark Age Cold Period (DACP). And the strong rainfall caused by the abnormal atmospheric circulation during the period of climate transition and abrupt change may led to the frequent occurrence of extreme flood events in the source region of the Yellow River. These findings are important for understanding the response of regional fluvial system to high climatic instability and provide a new perspective for us to analyze the risk of flood disasters on the Tibetan Plateau under the background of climate change.

Improvement in the performance and efficiency on self-deficient CaTiO3: Towards sustainable and affordable new-generation solar cells

Thin films of pure and self-deficient calcium titanites i.e., CaTiO3, Ca1-αTi1O3, CaTi1-βO3 and CaTiO3-γ have been deposited on ITO substrate using dip coating method. X-ray diffraction and Scanning electron Microscopy (SEM) analysis confirm the structural and morphology of all deposited thin films. Photocurrent measurement has been done, and it is observed that during the incidence of UV light on the as-prepared device (i.e., in the “ON” state), a significant increase in photocurrent (IUV) at zero voltage was observed in case of O deficient CaTiO3, while in case of Ti and Ca deficient thin films smaller values of photocurrents were seen. Responsivity and detectivity of deposited thin films of all self-deficient CaTiO3 were found to be maximum in the UV region while they also showed smaller contributions in the visible range possibly due to the presence of self-deficiency. The self-deficient sample exhibits lower resistance (higher recombination rate) than the pure sample at low voltage, but at higher voltage, it is almost identical. Furthermore, theoretical calculations have been performed using the first-principles density-functional theory to validate the experimental findings on self-deficient CaTiO3. Incident-photon-to-current efficiency (IPCE) and current density have also been measured for all deficient CaTiO3 samples. Maximum IPCE have been found in the range 25%− 28% for Ti and O deficient samples in the UV range (280–400 nm). We argue that first-principles DFT calculations combined with the experimental measurements on self-deficient CaTiO3 thin films offer a reliable way to enhance the performance of perovskite-based solar devices.

Determination of heavy metals and their associated health risk assessment in the commonly available sunblocks

ABSTRACT The present study was conducted to evaluate the concentrations of heavy metals in various brands of sunblocks with an emphasis on their health risk assessment. A Pilot study was conducted in Lahore, Pakistan, to know the sunblocks using behaviour and the most commonly used sunblock among youth. Samples were collected from different pharmacies and shopping malls in Lahore, Pakistan. Flame atomic absorption spectrometer and ICP-OES were used to detect heavy metals. The Highest detected values of Pb, Cd, Ni and Ti were 5.755 ± 0.0901 mg/kg, 2.49 ± 0.0595 mg/kg, 5.3 ± 0.3744 mg/kg and 4 ± 0.3298 mg/kg, respectively. Concentrations of heavy metals (Pb, Cd, Ni, and Ti) exceed the (EU) standards. The Value of the Margin of safety (MoS) was greater than 100 (acceptable) for all heavy metals except Cd. Hazard Index (HI) was less than 1, and the value of the lifetime cancer risk (LCR) was in acceptable range (10−6 to 10−4). There is need fornational standards and policy guidelines to create awareness and impose restrictions on the usage of toxic metals in consumer products to safeguard public health and the environment.

Using Zircons to Disentangle Back-Veining and Hybridization of Diorite Dykes: an Example From the Gangdese Arc, Tibet

AbstractThermo-chemical modeling and chemical data suggest that the genesis of arc melts commonly involves re-melting of older intrusions, triggered by the injection of mantle-derived melts, followed by magma mixing. Remelting and mixing may lead to complex zircon populations, which can be used to gain insights into the conditions of mixing. This paper investigates a case where such processes can be studied through the compositional and thermal record provided by zircons preserved in a diorite dyke swarm that remelted host rock tonalites in the Gangdese Batholith in Tibet. Autocrystic zircons from the diorite yield consistent ages of 46 to 47 Ma even though they can be altered, having highly enriched trace elements, reaching ~1 wt % in Fe, Ca, Y, U, Th, and anomalously high values of LREE and Ti. Granitic magmas derived from the tonalite, back-veined the dykes and mixed with the dioritic mush, transferring small quantities of 77–79 Ma zircon xenocrysts. The xenocrysts are euhedral with little evidence for resorption, indicating that they were apparently stable during the process of tonalite anatexis and transfer to the diorite magma. This requires that: (i) tonalite melting occurred at low temperatures with minimal zircon dissolution, and (ii) the diorite either cooled rapidly before significant resorption of the grains or was already saturated in zircon when mixing occurred. Zircon saturation temperatures of the diorite are relatively low, indicating that xenocrystic zircons were transferred to a highly crystalline dioritic mush. This requires either liquefaction by injection of the back-veining felsic magma to allow for mixing, or pervasive throughflow of the diorite mush by the felsic magma leaving behind zircon xenocrysts. The findings suggest that the dykes triggered low-T, water-fluxed melting of the host tonalite and that these anatectic melts invaded the diorite mush initially through the interstices leading to mixing. This may have caused the breakdown of the crystalline framework leading to liquefaction and renewed magma flow. Dyking and assimilation of wall-rock through back-veining as recorded in these rocks could be common in transcrustal arcs. However, this process could be hidden due to a combination of the similarity in the isotopic and chemical nature of arc rocks and resorption of zircon xenocrysts during mixing. This process may explain some complex chemistry of arc magmatic rocks and their minerals that are not easily explained by endmember models, such as pure re-melting of older arc rocks or fractional crystallization of mantle-derived melts.

Applicability of Machine-Learned Regression Models to Estimate Internal Air Temperature and CO2 Concentration of a Pig House

Carbon dioxide (CO2) emissions from the livestock industry are expected to increase. A response strategy for CO2 emission regulations is required for pig production as this industry comprises a large proportion of the livestock industry and it is projected that per capita pork consumption will rise. A CO2 emission response strategy can be established by accurately measuring the CO2 concentrations in pig facilities. Here, we compared and evaluated the performance of three different machine learning (ML) models (ElasticNet, random forest regression (RFR), and support vector regression (SVR)) designed to predict CO2 concentration and internal air temperature (Ti) values in the pig house used to regulate a heating, ventilation, and air conditioning (HVAC) control system. For each ML model, the hyperparameter was optimised and the predictive accuracy was evaluated. The order of predictive accuracy for the ML models was ElasticNet &lt; SVR &lt; RFR. Hence, random forest regression provided superior prediction performance. Based on the test dataset, for Ti prediction by RFR, R2 ≥ 0.848 and the root mean square error (RMSE) and mean absolute error (MAE) were 0.235 °C and 0.160 °C, respectively, whilst for CO2 concentration prediction by RFR, R2 ≥ 0.885 and the RMSE and MAE were 64.39 ppm and ≤ 46.17 ppm, respectively.