Residual Solution Research Articles

Microstructure evolution of electron beam welded joints of Ti-43Al-9V-0.3Y and Ti-6Al-4V alloys

Ti-43Al-9V-0.3Y (at%) and Ti-6Al-4V (at%) alloys were successfully welded by electron beam to investigate the microstructure evolution of the joints. The results showed that the microstructure of the weld is comprised of α2-Ti3Al, γ-TiAl, together with a few residual α-TiAl solid solution and B2 phase (ordering by β-TiAl solid solution). The casting structure is formed during the solidification process of the weld, which inevitably causes component segregation in some parts of the joint. In high Al content regions, Al element drives α phase ordering into α2 phase, and eventually introduces the formation of α/γ or α2/γ lamellar structures. Conversely, in some regions with low Al content, α phases hardly experience microstructure evolution and thus remains to room temperature.

Inverse Modeling of Gravity Data with Two Layers Density in Sedimentary Basin Structure

Study of sedimentary basin structure and basement variation in the subsurface using gravity methods are very common in early stage of hydrocarbon exploration. Most of inverse modeling are designed with several series of juxtaposed vertical prism in the subsurface. In this study, we utilize two layers of vertical prism below each gravity stations to represent homogeneous density of sedimentary layer and basement in the subsurface. In order to reach best miss-fit data we used iterative calculation utilizing differences between observed and calculated data. Performance of iterative calculation will attempt to find solution of interface density in the subsurface. In this paper, we use two synthetic data of symmetrical sedimentary basin model for inversion performance test. The performance test will evaluate the effect of initial model, exploration well data, topographic data, and noisy data effect. Based on synthetic data test, the performance of iterative method provide small order of miss-fit data with residual solution model of noisy data in the range -44 to 35 meters. Real data application identified three shallow sedimentary layer and two deeper sedimentary layer in the study area.

Efficiently removing Pb(II) from wastewater by graphene oxide using foam flotation

The removal of Pb(II) from wastewater by graphene oxide (GO) using foam flotation was first investigated. Effects of initial solution pH, and the dosage of GO, emulsified kerosene and terpenic oil on the Pb(II) removal and turbidity of the residual solution were systematically examined. The experimental results showed that the initial solution pH and dosage of GO significantly affected the removal of Pb(II), and more than 99% of Pb(II) could be removed under the optimum conditions. The turbidity of the residual solution could decrease to 1.4 NTU at the optimal dosage of emulsified kerosene and terpenic oil. Moreover, the flotation-desorption cycles were carried out to evaluate the practical reusability of GO, and the Pb(II) removal maintained as high as 84.9% in the sixth regeneration. It indicated that GO could be efficiently reused in the process of foam flotation. This study provides an effective strategy for the selection of an optimized method to remove the spent GO from solution compared with the conventional methods including sedimentation, centrifugation and filtration, etc.

Thorough conversion of CO2 through two-step accelerated mineral carbonation in the MgCl2-CaCl2-H2O system

Abstract This study describes a two-step accelerated mineral carbonation technology at moderate temperatures and atmospheric pressure by choosing the “problematic ions for seawater utilization” as mineralizers in the simplified seawater-MgCl2-CaCl2-H2O system, that is, Ca2+ as the first mineralizer and Mg2+ in the residual solution as the second. Not only can carbonate ions generated from the absorption and ionization of CO2 be fixed by Ca2+ through the first carbonation process with the added alkali source, MgO, but HCO3− in the residual solution can also be mineralized by Mg2+ through the second carbonation process. Meanwhile, pure CaCO3 and MgCO3·3H2O, which have the possible benefit of reuse, can be obtained as by-products. Then, more variables were set to optimize the technical conditions to enhance the decalcification rate and carbon sequestration ratio, reduce the reaction time during the first mineralization and attempt to realize the combination of HCO3− and Mg2+ by adding NaOH to produce MgCO3·3H2O as another by-product in a moderate environment during the second mineralization.

Facile synthesis of Ag/AgX (X = Cl, Br) with enhanced visible-light-induced photocatalytic activity by ultrasonic spray pyrolysis method

Ag/AgX (X = Cl, Br) plasmonic photocatalysts were synthesized via a facile one-pot ultrasonic spray pyrolysis method, wherein no additional issues such as high pressure, surfactants and reducing agents were required. The structure, morphology, and optical property of the as-prepared photocatalysts was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet–visible light absorption spectra and total organic carbon (TOC). The results showed that Ag/AgX photocatalysts have excellent photocatalytic performance for the photodegradation of methyl orange (MO) and methylene blue (MB) pollutants under visible light illumination, and the photocatalytic activity maintains a high level after seven cycles. Metallic Ag0 particles nucleate on the surface of AgX uniformly through the thermal decomposition of residual AgNO3 solution, which enhanced the interaction between Ag0 and AgX. The outstanding photocatalytic activity benefits from the small size and high dispersion of Ag0 nanoparticles and the enhanced interaction between Ag0 and AgX.

Combined multi-step precipitation and supported ionic liquid phase chromatography for the recovery of rare earths from leach solutions of bauxite residues

Rare-earth elements (REEs) were efficiently recovered by a supported ionic liquid phase (SILP) after iron(III) precipitation from simulated bauxite residue (BR) leachates in sulfuric acid media, since leaching of BR with sulfuric acid is more feasible than leaching with other mineral acids. The SILP betainium sulfonyl(trifluoromethanesulfonylimide) poly(styrene-co-divinylbenzene) [Hbet-STFSI-PS-DVB] exhibits a high selectivity for the rare-earth elements (REEs) over other elements in acidic BR leachates. However, scandium(III) uptake by the [Hbet-STFSI-PS-DVB] from sulfuric acid leachates is difficult due to strong electrostatic interactions of small scandium(III) ions with sulfate anions. Sulfuric acid leachates generally contain high concentrations of base metal ions like iron(III) and this reduces the efficiency of the [Hbet-STFSI-PS-DVB] for uptake of REEs. Therefore, a precipitation step for iron(III) removal with aqueous ammonia solution was introduced, as a simple and economically viable pretreatment step of BR leachate, prior to the REEs recovery by the SILP. Iron(III) precipitation from sulfuric acid BR leachates increased the efficiency of purification by column chromatography. Additionally, scandium(III) phosphate precipitation, after iron(III) removal, was performed in order to compare and assess the optimum route for scandium(III) purification between the two common processes: selective precipitation and elution chromatography. After scandium(III) phosphate precipitation, the recovery and subsequent purification of the remaining REEs on the [Hbet-STFSI-PS-DVB] column were also examined, and resulted in a higher purity of these REEs.

Superhydrophobic candle soot/PDMS substrate for one-step enrichment and desalting of peptides in MALDI MS analysis

Superhydrophobic substrate is applied in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) detection due to its confinement effect. The weak interaction of superhydrophobic surface with water/salts makes it potential in one-step enrichment and desalting of peptide in MALDI MS analysis. We fabricate a superhydrophobic substrate by spin-coating poly(dimethyl siloxane) (PDMS) on a candle soot layer. On this substrate, the peptide analytes can be confined and enriched in a small area due to the confinement effect and its strong hydrophobic interactions with PDMS. Meanwhile, the desalting can be easily realized by removing the residual solution after the absorption of analyst molecules due to the weak interaction between water/salt contaminants and the superhydrophobic surface. Using this substrate, angiotensin III (Ang III) in the presence of salt with high concentration (2 M or saturated) can be analyzed, and the peptide sequence coverage of 10 μg/mL myoglobin (MYO) and bovine serum albumin (BSA) digests is enhanced to 51% and 26%, which is 37% and 21% analyzed with the commercial ZipTipC18 pipette tips. The LOD of bacitracin A (Bac A) in milk with this substrate is 100 pM and nearly 360 times lower than the LOD of standard testing method. This substrate has potential practical applications in proteomics research and actual sample analysis.

Fractionation of Mg isotopes by clay formation and calcite precipitation in groundwater with long residence times in a sandstone aquifer, Ordos Basin, China

Compared with the numerous studies on river and soil waters, studies on Mg isotopes of groundwater are limited. In this study, a sandstone aquifer in the Ordos Basin, China with contrast contents of Mg in shallow and deep groundwater is selected to examine the behavior of Mg isotopes during groundwater circulation. The δ26Mg values of shallow groundwater are within the range of widely reported results of groundwater, while those of deep groundwater are found to be as light as −3.30‰ to −2.13‰. Assuming that shallow groundwater is an endmember, 87Sr/86Sr ratios show that calcite dissolution has contribution to low δ26Mg of deep groundwater, but mixing alone cannot explain the coupled low δ26Mg and low Mg contents. The removal of Mg in deep groundwater is found to be mainly caused by incorporating into neoformed clay minerals, which further lowers δ26Mg. For the deep groundwater samples denoted as G1 and G3, the relationship between δ26Mg and 1/Mg has been quantitatively explained by the superposition of calcite dissolution and clay formation with a fractionation factor (αclay–water) of 1.0003. For samples denoted as G2, in addition to calcite dissolution and clay formation, high proportion of Mg in the residual solution are further removed via precipitation of low-Mg calcite, which leads to increased δ26Mg. There are increasingly stronger degrees of clay formation in G3, G1, and G2 due to the increasingly longer travel distances and travel times of groundwater from recharge to discharge areas. This study enhances understanding on the factors controlling Mg isotopes of groundwater, as well as the geochemical processes of subsurface water-rock interactions in sandstone aquifers.

Heterostructure Ag@WO3–x Composites with High Selectivity for Breaking Azo-bond

The heterostructure Ag@WO3–x(x=0.1 or 1) composites with high selectivity for breaking azo-bond were obtained by in situ reduction of Ag2WO4. The crystal structure and morphology of Ag@WO3–x were characterized by X-ray powder diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscope(TEM). The residue solution of methyl orange(MO) after degradation was tested by gas chromatograph mass spectrometer (GCMS) to analyze the exact components. The results indicate that the products after degradation are N,N-dimethylaniline, N,N-dimethyl-p-phenylenediamine and sulfanilic acid. This is caused by specific breaking of azo-bond in MO. The azo-bond breaking of MO by Ag@WO3–x could occur in dark without any light illumination. Therefore, we proposed a possible mechanism for this azo-bond breaking reaction based on the reaction condition and results.

A Survey of Atmospheric Pollen and Spores in North-Western Nigeria

The incidence of airborne pollen occurring as aeroallergens of varied levels at different periods of the year has generated some public health concern globally. The present study was conducted in order to examine the monthly depositional rate of airborne pollen and fern spores, as well as the impact of meteorological parameters and local plants on pollen distribution at two study sites in Kaduna and Sokoto States of North Western Nigeria. The study spanned a period of one year, during which a modified Tauber pollen sampler was employed in the collection of atmospheric pollen and fern spores; local plants were also enumerated. Residual solution was collected monthly, subjected to acetolysis and the treated residues were viewed for microscopic studies. The results reveal monthly distribution of airborne pollen and fern spore types at the study sites during the sampling period. Dominant pollen types in Kaduna State were those of Alchornea laxiflora, Pinus caribaea, Terminalia sp., Sapotaceae and Poaceae family. Pollen of Syzygium guineense, Alchornea sp., Sapotaceae and Poaceae dominated in Sokoto State. Spores of Pteris sp., Nephrolepis sp. and a trilete fern were also recovered at both locations. Some local plants in the immediate vegetation contributed to the aeroflora of these locations. No significant correlation was recorded between monthly total pollen concentrations and mean monthly meteorological parameters of the locations. It is imperative to investigate the allergenicity of these dominant pollen types, so as to aid pollen hypersensitive individuals in adopting appropriate prophylactic measures.

Seasoning Production from the Residual Waste Solution of Isada Krill Processing by Its Treatment under Subcritical Water Conditions

The residual waste solution obtained during the recovery of functional components from Isada krill was treated under subcritical water conditions. Properties of the treated solution, such as solid, protein, and carbohydrate contents, were measured. The characteristic smell of the solution was evaluated. The smell intensity increased with a rise in the treatment temperature by gasification of the soluble components. In particular, the treatment at 160–180℃ strengthened the shrimp-like fragrant smell and retained the unpleasant fishy and rotten smell at lower level. The treated solution, therefore, may serve as a promising seasoning ingredient. The gas chromatography mass spectrometry analysis of the smell revealed the formation of pyridine- and pyrazine-related compounds after the treatment that contributed to the improvement in shrimp-like flavor.

Mitigation of Mercury Contamination in an Ore Collection

The National Rock and Ore Collection at the Smithsonian Institution’s National Museum of Natural History includes mercury ore specimens stored at its Museum Support Center in Suitland, Maryland. Two decades after the ore collection was moved from historic metal clad wooden cabinets with felt gaskets to modern steel cabinets with neoprene foam gaskets, it became apparent that elemental mercury vapor generated from the specimens was accumulating within the storage units, creating visible mercury deposits on cabinet interior surfaces and drawers, as well as the paperboard storage trays and paper specimen labels inside the drawers. Concerns were raised about the potential health hazard to users of the collection, as well as potential cross-contamination of non-mercury-bearing specimens, housing materials and equipment. The Museum’s collection manager, conservator, and industrial hygienist developed three phases of mitigation strategies, which were applied and analyzed for effectiveness between 2011 and 2016. The first phase involved creating special vapor barrier packaging for each mercury ore using Marvelseal®, welded on three sides by the supplier, and frame sealing tape to secure the fourth side; disposal of all trays and replacement of trays for the non-mercury-bearing specimens; extensive cleaning of the cabinet interiors using Mercury Absorb Sponges; and lining each drawer and cabinet with MicroChamber scavenger sheets. Utilizing a Jerome Mercury Vapor Analyzer, measurements indicated a 40-50% reduction in mercury concentrations within the affected cases. There were still visible residual mercury deposits, so a second, more rigorous phase of cleaning was conducted on all accessible interior cabinet and drawer surfaces, paying special attention to unpainted metal hardware. A modified solution of Lugol’s iodine was used, followed by isopropyl alcohol wipes to remove the residual iodine solution. This second phase led to a further reduction in mercury vapor of 60-80% from the original measurements. The cases were securely closed for one year, and subsequent measurements indicated a significant re-accumulation of mercury vapor. During the third phase of mitigation, zeolite scavenger sheets were inserted between drawers and over bagged specimens, and MicroChamber sheets from the second phase were replaced. This resulted in mercury vapor concentration reductions back to 60-80% of the original measurements. However, the median concentration still exceeded the conservative occupational health exposure limit of 0.025 mg/M3. Subsequent investigation suggests that residual mercury residue on inaccessible interior cabinet surfaces is the limiting factor preventing complete and permanent mitigation.

Self-cleaning threaded rod spinneret for high-efficiency needleless electrospinning

High-efficiency production of nanofibers is the key to the application of electrospinning technology. This work focuses on multi-jet electrospinning, in which a threaded rod electrode is utilized as the needless spinneret to achieve high-efficiency production of nanofibers. A slipper block, which fits into and moves through the threaded rod, is designed to transfer polymer solution evenly to the surface of the rod spinneret. The relative motion between the slipper block and the threaded rod electrode promotes the instable fluctuation of the solution surface, thus the rotation of threaded rod electrode decreases the critical voltage for the initial multi-jet ejection and the diameter of nanofibers. The residual solution on the surface of threaded rod is cleaned up by the moving slipper block, showing a great self-cleaning ability, which ensures the stable multi-jet ejection and increases the productivity of nanofibers. Each thread of the threaded rod electrode serves as an independent spinneret, which enhances the electric field strength and constrains the position of the Taylor cone, resulting in high productivity of uniform nanofibers. The diameter of nanofibers decreases with the increase of threaded rod rotation speed, and the productivity increases with the solution flow rate. The rotation of electrode provides an excess force for the ejection of charged jets, which also contributes to the high-efficiency production of nanofibers. The maximum productivity of nanofibers from the threaded rod spinneret is 5–6 g/h, about 250–300 times as high as that from the single-needle spinneret. The self-cleaning threaded rod spinneret is an effective way to realize continuous multi-jet electrospinning, which promotes industrial applications of uniform nanofibrous membrane.

Residual symmetry, CRE integrability and interaction solutions of the (3+1)-dimensional breaking soliton equation

Residual symmetry of the (3+1)-dimensional breaking soliton equation is obtained and localized to a Lie point symmetry in a properly prolonged system. The general form of Lie point symmetry group and the corresponding symmetry reduction solutions of the prolonged system are obtained by using the standard Lie symmetry method, which include various interaction solutions between solitons and nonlinear background waves of the (3+1)-dimensional breaking soliton equation. Furthermore, the (3+1)-dimensional breaking soliton equation is proved to be integrable in the sense of having consistent Riccati expansion. Based on this property, some new Bäcklund transformations of the (3+1)-dimensional breaking soliton equation are obtained, from which interaction solutions between solitions and cnoidal waves are explicitly given.

Effect of process variables on volumetric mass transfer coefficient in wet purification of crude biodiesel

ABSTRACTIn this study, the effect of process variables on the volumetric mass transfer coefficient (Kca) of residual solutes in biodiesel during wet purification was investigated. A purification process was carried out using distilled water batch-wise at varying washing times, temperatures and biodiesel-to-water (BW) ratios. The amounts of solutes in biodiesel and water phases were determined at each washing stage using standard methods. The linear driving force kinetic model equation was used to estimate the Kca. The concentration of solutes in the crude biodiesel were 12.02 mg/dm3, 0.0168%, 0.00159% and 0.02749% for catalyst, methanol, soap and glycerol, respectively. Using a BW ratio of 1:2, a time of 30 min and a temperature of 40°C in a single-stage washing process, optimum solute removal was achieved. A minimum of 250 cm3 of water sufficiently washed 100 cm3 of the biodiesel in a five-stage washing process at 40°C to achieve a solute concentration of 0.13 mg/dm3, 0.002 × 10(-4)%, 0.13 × 10(-4)% and 0.057 × 10(-4)% for catalyst, methanol, soap and glycerol, respectively. There was increase in Kca as the BW ratio was decreased from 2:1 to 1:4. The Kca also increased as the temperature was increased from 30 to 50°C.

A lead analysis based on amine functionalized bimodal mesoporous silica nanoparticles in human biological samples by ultrasound assisted-ionic liquid trap-micro solid phase extraction

A simple and applied method based on ultrasound assisted-Ionic liquid trap-micro solid phase extraction (USA-ILT-μSPE) was demonstrated for preconcentration/separation of lead (Pb) in human blood and urine samples. By proposed method, the amine-functionalized bimodal mesoporous silica nanoparticles (NH2-UVM7) as solid phase sorbent was used for lead analysis in human biological samples at pH ≈ 7.0. After shaking/centrifuging of sample, the Pb (II) was extracted with NH2-UVM7 without any chelating agents, trapped in ionic liquid phase and settled down in conical centrifuge tube as a residual solution [Pb→:NH2-UVM7]. Finally, the lead ions was back extracted from residual solution and determined by atom trap flame atomic absorption spectrometry (AT-FAAS). Under the optimal conditions, the linear range (LR), limit of detection (LOD) and preconcentration factor (PF) were obtained (10–950 μg L−1; 2.0–210 μg L−1), (2.8 μg L−1; 0.6 μg L−1) and (19.8; 99.7) for human blood and urine samples, respectively (% RSD < 1, intra-day). The reusability and adsorption capacity of the sorbent were also obtained 24 and 213.8 mg g−1, respectively. Validation of methodology was confirmed by certified reference materials (NIST, CRM).

In vitro degradation and in vivo toxicity of NanoMatrix3D® polycaprolactone and poly(lactic acid) nanofibrous scaffolds.

Nanofibrous materials present unique properties favorable in many biomedicine and industrial applications. In this research we evaluated biodegradation, tissue response and general toxicity of nanofibrous poly(lactic acid) (PLA) and polycaprolactone (PCL) scaffolds produced by conventional method of electrospinning and using NanoMatrix3D® (NM3D® ) technology. Mass density, scanning electron microscopy and in vitro degradation (static and dynamic) were used for material characterization, and subcutaneous, intramuscular and intraperitoneal implantation - for in vivo tests. Biochemical blood analysis and histology were used to assess toxicity and tissue response. Pore size and fiber diameter did not differ in conventional and NM3D® PLA and PCL materials, but mass density was significantly lower in NM3D® ones. Scaffolds made by conventional method showed toxic effect during the in-vivo tests due to residual concentration of chloroform that released with material degradation. NM3D® method allowed cleaning scaffolds from residual solutions that made them nontoxic and biocompatible. Subcutaneous, intramuscular and intraperitoneal implantation of PCL and PLA NM3D® electrospun nanofibrous scaffolds showed their appropriate cell conductive properties, tissue and vessels formation in all sites. Thus, NM3D® PCL and PLA nanofibrous electrospun scaffolds can be used in the field of tissue engineering, surgery, wound healing, drug delivery, and so forth, due to their unique properties, nontoxicity and biocompatibility. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2200-2212, 2018.

Non-hazardous Treatment for Barium Slag Using Phosphogypsum

Barium compounds are important chemical materials obtained from barite. Barium slag (BS) is an insoluble alkali residue derived from the product of barium compounds following the process of carbothermal reduction and water/acid leaching. In this study, two BS-derived samples named BS-YP and BS-ZN were characterized using analytical methods of XRF, ICP-MS and XRD. The environmental impacts of both BS residues were assessed. From the data of corrosivity and extraction toxicity test, the extraction solutions of BS-YP and BS-ZN residues had barium concentrations as high as 1285 and 1325 mg/L, respectively, much higher than the limit value (100 mg/L for barium) for hazardous materials, and both were identified as hazardous materials. To address this issue, acid industrial waste phosphogypsum (PG) was proposed to neutralize BS residues and to immobilize barium ion due to the slightly soluble sulfate included. It is demonstrated that with the ratios of 10:1–20 (BS:PG), the barium concentration can be lowered to < 2 mg/L in both BS residues.

Effect of solution potential on selective separation of metals from acid wastewater by controlling potential

Abstract In view of the difficulties in separating similar metals from acidic wastewater, a new process is proposed to selectively separate metals by controlling potential. In this study, the effects of solution potential on precipitation ratio and separation efficiency were investigated. The potential was controlled by adding sodium sulfide or xanthate and was monitored by an MT320-SpH instrument with a Pt electrode and a calomel electrode. E-pH diagrams of Me-S-H2O system were plotted through thermodynamic calculations. The results revealed that with the drop of solution potential, the metal precipitation ratios increased. Cu2+, Co2+, and Zn2+ can be selectively separated and completely precipitated under controlling potential at 330 mV, 125 mV and 30 mV, respectively. Mn2+ could be recovered by carbonate precipitation from the residual solution after Zn removal. The precipitation ratios of Cu2+, Co2+, Zn2+, and Mn2+ were as high as 99%.

Enzyme-free homogeneous electrochemical biosensor for DNA assay using toehold-triggered strand displacement reaction coupled with host-guest recognition of Fe3O4@SiO2@β-CD nanocomposites

Taking advantages of the toehold-triggered strand displacement reaction (TSDR) and host-guest interaction of β-cyclodextrin (β-CD), a facile enzyme-free and homogeneous electrochemical sensing strategy was designed for the sensitive assay of target DNA using Fe3O4@SiO2@β-CD nanocomposites and ferrocene-labeled hairpin DNA (H-1) as the capture and electrochemical probes, respectively. Upon addition of target molecule, the initiated TSDR process induced the conformational change of H-1, and subsequently stimulated the dynamic assembly of assist probes (A-1 and A-2) to generate H-1:A-1:A-2 duplex along with the release of target sequence. The released target could drive the next TSDR recycling and finally result in the formation of numerous DNA duplex. After the molecular recognition of Fe3O4@SiO2@β-CD nanocomposites, a large number of duplex were easily separated from the supernatant solution under an external magnetic field, which led to a decreased H-1 concentration in residual solution, concomitant with a remarkable reduction of peak current. Under the optimized conditions, wide linear range (1–5000 pM), low detection limit (0.3 pM), desirable reproducibility, good selectivity, and satisfactory practical analysis were obtained by the combination of the superior recognition capability of β-CD, TSDR-induced signal amplification, and homogeneous electroanalytical method. The proposed detection strategy could offer a universal approach for the monitoring of various biological analytes via the rational design of probe sequences.