SA Samples Research Articles

N-glycan signature of neutrophil function in a Staphylococcus aureus skin infection model by mass spectrometry imaging

Abstract Staphylococcus aureus (Sa) is a public health concern due to the rise of antibiotic-resistant strains. In humans, elevated risk is associated with Tumor Necrosis Factor (TNF) inhibition. Neutrophils expressing TNF receptors (TNFR1 and TNFR2) respond to Sa skin infection in a mouse model. TNFR2 activation induces PAD4 (peptidylarginine-deiminase-4) which leads to neutrophil extracellular traps (NET) synthesis, increasing host defenses. Alterations in PAD4 and N-glycans are related to increased skin infections and the spatial glycosylation signature during the skin response to Sa is unknown. We compared N-glycan signatures in neutrophil region between wildtype (WT), TNFR1 KO, TNFR2 KO and PAD4-/- groups. Mice were intradermally injected with Sa and skin samples collected for analysis by mass spectrometry imaging. We sprayed PNGaseF on prepared FFPE sections to cleave the N-glycans, sprayed with CHCA matrix, and evaluated in positive ion mode at 50mm spatial resolution on a timsTOF Flex (Bruker Daltonics). Differential N-glycan signatures were identified using a histology-guided approach limiting the comparisons to the PMN region. PAD4-/- showed higher intensity of N-glycans than all groups. However, specific N-glycans were higher in TNFR1 KO than PAD4-/- and TNFR2. A lower profile was found in TNFR2 KO vs. WT. We concluded that each group has a specific N-glycan signature which can be attributed to unique immune responses to Sa infection and NET formation.

Influence of Various Heat Treatments on Microstructures and Mechanical Properties of GH4099 Superalloy Produced by Laser Powder Bed Fusion.

The microstructures and mechanical properties of a γ'-strengthened nickel-based superalloy, GH4099, produced by laser powder bed fusion, at room temperature and 900 °C are investigated, followed by three various heat treatments. The as-built (AB) alloy consists of cellular/dendrite substructures within columnar grains aligning in <100> crystal orientation. No γ' phase is observed in the AB sample due to the relatively low content of Al +Ti. Following the standard solid solution treatment, the molten pool boundaries and cellular/dendrite substructures disappear, whilst the columnar grains remain. The transformation of columnar grains to equiaxed grains occurs through the primary solid solution treatment due to the recovery and recrystallization process. After aging at 850 °C for 480 min, the carbides in the three samples distributed at grain boundaries and within grains and the spherical γ' phase whose size is about 43 nm ± 16 nm develop in the standard solid solution + aging and primary solid solution + aging samples (SA and PA samples) while the bimodal size of cubic (181 nm ± 85 nm) and spherical (43 nm ± 16 nm) γ' precipitates is presented in the primary solid solution + secondary solid solution + aging sample (PSA samples). The uniaxial tensile tests are carried out at room temperature (RT) and 900 °C. The AB sample has the best RT ductility (~51% of elongation and ~67% of area reduction). Following the three heat treatments, the samples all acquire excellent RT tensile properties (>750 MPa of yield strengths and >32% of elongations). However, clear ductility dips and intergranular fracture modes occur during the 900 °C tensile tests, which could be related to carbide distribution and a change in the deformation mechanism.

Length effect of crosslinkers on the mechanical properties and dimensional stability of vitrimer elastomers with inhomogeneous networks

Inhomogeneous network construction is a useful strategy to solve the trade-off between mechanical strength and creep in vitrimer rubbers. But it is still lack of tools to tune the mechanical properties and network dynamics of this new system. In this paper, uneven distribution of functional groups was realized by sequential coordination polymerization of myrcene and isoprene and epoxidation. The following epoxidation and curing generated VMI-x samples with inhomogeneous network. Polyisoprene was used to prepare control samples called VPI-x with homogeneous network. Different lengths of dicarboxylic acid crosslinkers (SA = succinic acid, HA = heptanedioic acid, DA = decanedioic acid) were used to probe their effects on dynamic behaviors, mechanical properties and recyclability. Morphological test and nanomechanical mapping confirmed the inhomogeneous feature of VMI-x samples. For both inhomogeneous and homogeneous samples, SA and DA crosslinkers brought higher tensile strength and modulus, earlier SIC phenomenon and higher orientation percentage of amorphous molecular chains than those of HA, which are ascribed to extra permanent cross-linking existing in SA samples and transition entanglements existing in DA samples. However, the constrain effect of SA crosslinker is too strong in inhomogeneous network to sacrifice the extensibility, which is much smaller than those of HA and DA. SA and DA samples also present restricted segmental motion and superior creep resistant properties compared to HA samples according to the results of broadband dielectric spectroscopy and DMA test. Differently, at high temperature above 130 °C, the stress relaxation, topology freezing transition temperature (Tv) and recycling efficiency of strength are dominated by the crosslinker length monotonically, probably due to the disentanglement of DA crosslinkers. Compared to homogeneous network, inhomogeneous ones showed obvious enhanced mechanical properties, lower hysteresis, quicker segmental relaxation, lower creep and quicker network relaxation. This work demonstrates that crosslinker lengths could tune the vast aspects of vitrimer elastomers and is a non-negligible factor to determine their properties, especially for those with inhomogeneous networks.

Listener Factors Related to the Perception of Accented Speech

The purpose of this study was to explore the effect of the listener’s education and occupation on intelligibility, comprehensibility (ease of understanding), and accentedness in speakers of Russian-accented American English (RA), Southern-accented American English (SA), and General American English (GAE). Native English listeners ( N=126) rated various aspects of each sample presented via a questionnaire. All aspects of speech other than rate were rated highest in the GAE sample followed by the SA and RA samples. Intonation and fluency aspects of accented speech appeared to be influenced by the differences in educational or occupational backgrounds. The study also discussed additional influential factors for the perception of accented speech such as clarity, accentedness, and acceptability of speech for SLPs. This study contributes to increase the awareness of factors associated with the negative perception of regional and foreign accents.

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&lt;0.001). Thermal aging reduced μSBS regardless the surface treatment and resin cement used. There was interaction between surface treatment and resin cement (p &lt;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.

Effect of heat treatment on CuCrZr alloy fabricated by selective laser melting: microstructure evolution, mechanical properties and fracture mechanism

In this work, the effect of heat treatment on the microstructure and mechanical properties of CuCrZr alloy fabricated by selective laser melting (SLM) was investigated. The results demonstrated that the optimal comprehensive performance of the tensile strength (569.7 MPa) and the hardness (160 HV) was obtained by direct ageing (DA) at 470 °C for 60 min. The tensile strength of the CuCrZr alloy in the case of the solution treatment (ST) was 281.0 MPa, and the tensile strength of the CuCrZr alloy in the case of the solution + ageing treatment (SAT) reached 356.5 MPa. As the ST temperature increases, the amount of particles inside the grains dissolving into the matrix increases, the precipitation phase decreases significantly. and the precipitated phase increases slightly at the grain boundary. Zr-rich phase precipitation was observed at the grain boundaries of SA and SAT samples. The SAT and DA samples underwent recrystallisation and an increase in grain size. The grain orientation in the XZ direction of the ST samples was mainly in the <110> direction; in the case of the SAT and the DA samples grains, the <100> orientation became stronger.

Moderation analysis of exchange rate, tourism and economic growth in Asia.

This study brings novelty to the tourism literature by re-examining the role of exchange rate in the tourism-growth nexus. It differs from previous tourism-led growth narrative to probe whether tourism exerts a positive effect on economic growth when the exchange rate is accounted for. Using a moderation modelling framework, instrumental variables general method of moments (IV-GMM) and quantile regression techniques in addition to real per capita GDP, tourism receipts and exchange rate, the study engages data on 44 Asian countries from 2010 to 2019. Results from the IV-GMM show that: (1) tourism exerts a positive effect on growth; (2) exchange rate depreciation hampers growth; (3) the interaction effect is positive but statistically not significant; and (4) results from EAP and SA samples are mixed. For the most part, constructive evidence from the quantile regression techniques reveals that the impact of tourism and exchange is significant at lower quantiles of 0.25 and 0.50 while the interaction effect is negative and statistically significant only for the SA sample. These are new contributions to the literature and policy recommendations are discussed.

315. Standardized Measurement of SARS-CoV-2 Viral Load Over Time in Respiratory Compartments and in Response to Remdesivir Treatment

Abstract Background Two years into the pandemic, clinicians do not have access to a standardized measurement of SARS-CoV-2 viral load (VL) that allows for VL comparison across clinical specimens and different assays. Reliable VL measurement in diverse respiratory specimens, over time, and in response to treatments such as remdesivir (RDV), could better inform treatment and prevention. Methods To investigate the use of a standardized VL assay in respiratory specimens, we enrolled patients hospitalized with COVID-19 in Providence, RI, with/without RDV exposure; collected serial samples from 4 compartments (nasopharyngeal-NP, nasal-NA, oropharyngeal-OP, saliva-SA) in 3 visits during the 1st week of hospitalization; and characterized SARS-CoV-2 VL using a ChromaCode HDPCR™ quantitative research use only assay, calibrated to the first World Health Organization (WHO) International Standard (IS). Linear mixed effects models and associated regression coefficients were used to analyze inter-compartmental VL differences at enrollment, over time, and with/without RDV. Results Of 35 participants (60% male; 70% White, 14% Hispanic/Latino, 49% RDV exposure), all had visit 1 samples (median hospital day 1, IQR 0-2; pre-RDV for those exposed); 80% visit 2 samples (median hospital day 2, IQR 1-8); and 37% visit 3 samples (median hospital day 4, IQR 3-7). Overall, 38 NP, 67 NA, 57 OP, and 67 SA samples were collected. Mean log VLs (Log10IU/mL) differed by compartment at visit 1 (NP 6.3, NA 4.9, OP 4.1, SA 5.6, p=0.0001) and significantly decreased over time in all compartments (p&amp;lt; 0.04 for all comparisons). Log VL change over time was not significantly different between compartments or between people treated/not treated with RDV. Conclusion We successfully measured respiratory intercompartmental SARS-CoV-2 VL differences among hospitalized patients using a standardized assay calibrated to the WHO IS. Dissemination of standardized VL measurement methods will allow accurate VL comparisons across assay types quantified in IU/mL and improve assessment of the impact of COVID-19 treatments. Inter-compartmental VL differences at baseline may indicate sampling variability or different viral burden. RDV did not appear to accelerate viral decay. Disclosures Curt Beckwith, MD, Gilead Sciences, Inc: Grant/Research Support Jon Steingrimsson, PhD, Gilead: Grant/Research Support Angela Caliendo, MD, PhD, ChromaCode: Advisor/Consultant|Danaher/Cepheid: Advisor/Consultant|First Light: Advisor/Consultant|Hologic: Grant/Research Support|ID Connect: Advisor/Consultant|Quidel: Advisor/Consultant|Visby: Advisor/Consultant Rami Kantor, MD, Gilead Sciences: Grant/Research Support.

Effects of Different Titanium Surface Treatments on Adhesion, Proliferation and Differentiation of Bone Cells: An In Vitro Study.

The objective of this study was to evaluate the impacts of different sandblasting procedures in acid etching of Ti6Al4V surfaces on osteoblast cell behavior, regarding various physicochemical and topographical parameters. Furthermore, differences in osteoblast cell behavior between cpTi and Ti6Al4V SA surfaces were evaluated. Sandblasting and subsequent acid etching of cpTi and Ti6Al4V discs was performed with Al2O3 grains of different sizes and with varying blasting pressures. The micro- and nano-roughness of the experimental SA surfaces were analyzed via confocal, atomic force and scanning electron microscopy. Surface free energy and friction coefficients were determined. hFOB 1.19 cells were seeded to evaluate adhesion, proliferation and osteoblastic differentiation for up to 12 d via crystal violet assays, MTT assays, ALP activity assays and Alizarin Red staining assays. Differences in blasting procedures had significant impacts on surface macro- and micro-topography. The crystal violet assay revealed a significant inverse relationship between blasting grain size and hFOB cell growth after 7 days. This trend was also visible in the Alizarin Red assays staining after 12 d: there was significantly higher biomineralization visible in the group that was sandblasted with smaller grains (F180) when compared to standard-grain-size groups (F70). SA samples treated with reduced blasting pressure exhibited lower hFOB adhesion and growth capabilities at initial (2 h) and later time points for up to 7 days, when compared to the standard SA surface, even though micro-roughness and other relevant surface parameters were similar. Overall, etched-only surfaces consistently exhibited equivalent or higher adhesion, proliferation and differentiation capabilities when compared to all other sandblasted and etched surfaces. No differences were found between cpTi and Ti6Al4V SA surfaces. Subtle modifications in the blasting protocol for Ti6Al4V SA surfaces significantly affect the proliferative and differentiation behavior of human osteoblasts. Surface roughness parameters are not sufficient to predict osteoblast behavior on etched Ti6Al4V surfaces.

Adhesion of auto-mixed and manual-mixed self-adhesive resin cements to dentin on exposure to long-term high-altitude pressure

PurposeThe purpose of this study is to test the shear-bond-strengths of auto-mixed and manual-mixed self-adhesive resin cement to dentin on long-term high-altitude pressure.Design/methodology/approachHuman molars were embedded in acrylic resin. Sixty composite resin discs were obtained. The composite resin discs were bonded to dentin using hand-mixed and auto-mixed self-adhesive resin cement. After cementation, the samples were stored in artificial saliva and divided into two subgroups (n = 30), hypobaric pressure and the atmospheric pressure group. The specimen underwent three pressure cycles per day for 100 days. The failure types were evaluated after debonding with scanning electron microscopy. The shear bond strength was tested with Universal Testing Machine. Analysis of variances/Tukey post hoc tests were used for statistical analysis. Groups were also evaluated by the Weibull modulus.FindingsRegardless of hypobaric pressure changes, the highest bond strength was examined in auto-mixed Panavia SA samples. A significant difference was found in both auto-mixed MaxCem EC and hand-mixed RelyX U200 group after exposure to hypobaric pressure compared to the control group.Originality/valueThe luting cement-type, mixing methods of cements and environmental pressure changes significantly influence the bond strengths. Dentists can use auto-mixed self-adhesive resins in patients likely to be exposed to hypobaric pressure.

Influence of heat treatment and pre-straining on dynamic precipitation and creep behavior of AZ91-0.5Y magnesium alloys

Herein, the effect of heat treatment and pre-straining on dynamic precipitation and creep properties of an extruded AZ91-0.5Y magnesium alloy is systematically investigated. Four kinds of samples processed by solid solution (SS), aged after solid solution (SA), pre-strained after solid solution (SP) and subsequently aged (SPA) were prepared. The creep tests were conducted at different temperatures, ranging from 150 to 180 °C, under various applied stresses, ranging from 50 to 70 MPa. The results reveal that the highest creep resistance is found in the SP sample, followed by SPA and SS samples, and the lowest creep resistance is exhibited by the SA sample. The microstructural results clarify that the creep resistance can be related to the type and density of dynamically precipitated Mg17Al12 phase. For the SS and SA samples, a high volume fraction of lamellar structures of Mg17Al12 is formed during creep test, making basal <a> slip and prismatic <a> slip as the dominant creep mechanisms. The twins introduced by the pre-straining contributed a high volume fraction of spherically-shaped Mg17Al12 phase, making pyramidal <c+a> slip and twinning as the dominant creep mechanisms for SP and SPA samples. The twinning and high volume fraction of spherically-shaped Mg17Al12 phase are the reasons for the optimal creep properties of the SP sample.

R-indexing the eBWT.

The extended Burrows Wheeler Transform (eBWT) was introduced by Mantaci et al. [TCS 2007] to extend the definition of the BWT to a collection of strings. In our prior work [SPIRE 2021], we give a linear-time algorithm for the eBWT that preserves the fundamental property of the original definition (i.e., the independence from the input order). The algorithm combines a modification of the Suffix Array Induced Sorting (SAIS) algorithm [IEEE Trans Comput 2011] with Prefix Free Parsing [AMB 2019; JCB 2020]. In this paper, we show how this construction algorithm leads to r-indexing the eBWT, i.e., run-length encoded eBWT and SA samples of Gagie et al. [SODA 2018] can be constructed efficiently from the components of the PFP. Moreover, we show that finding maximal exact matches (MEMs) between a query string and the r-index of the eBWT can be efficiently supported.

Effect of the irrigation method and genotype on the bioaccumulation of toxic and trace elements in rice

The total concentration of three toxic elements (As, Cd and Pb) and five oligoelements (Cu, Mn, Mo, Ni and Se) has been determined using an original and completely validated ICP-MS method. This was applied to rice grains from 26 different genotypes cultivated in the same soil and irrigated with the same water in three different ways: by the traditional continuous flooding (CF) and by two intermittent methods, the sprinkler irrigation (SP) and the periodical saturation of the soil (SA). The adoption of SP hugely minimizes the average amounts of almost all elements in kernels (−98% for As, −90% for Se and Mn, −60% for Mo, −50% for Cd and Pb), with the only exception of Ni, whose concentration increases the average amount found in the CF rice by 7.5 times. Also SA irrigation is able to reduce the amounts of As, Mo and Pb in kernels but it significantly increases the amounts of Mn, Ni and – mainly - Cd. Also the nature of the genotype determined a wide variability of data within each irrigation method. Genotypes belonging to Indica subspecies are the best bioaccumulators of elements in both CF and SP methods and, never, the worst bioaccumulators for any element/irrigation method combination. In the principal component analysis, PC1 can differentiate samples irrigated by SP by those irrigated by CF and SA, whereas PC2 provides differentiation of CF samples by SA samples. When looking at the loading plot Ni is negatively correlated to the majority of the other elements, except Cu and Cd having negative loadings on PC2. These results allow to envisage that a proper combination of the irrigation method and the nature of rice genotype might be a very valuable tool in order to successfully achieve specific objectives of food safety or the attainment of functional properties.

Initial mass uptake dynamics and diffusivity of cyclohexane vapor in nano-scale bitumen films coated on substrates with different degrees of hydrophilicity

Absorption of cyclohexane vapor into thin bitumen films with 0.5 wt% and 2 wt% bitumen coated on samples containing large spherical particles made up of borosilicate glass and fine particles with different chemical compositions (borosilicate glass versus kaolin clay) was studied using a gravimetric technique. Samples containing glass fines and clay fines are denoted as SA and SB, respectively. Fines refer to the particles with sizes less than 45 µm and their concentration varied from 5 to 20 wt% in SA and SB. The results clearly showed that the chemical composition of the fines significantly affected the cyclohexane initial mass uptake rate and that this rate exhibited a negative bitumen content dependence with the dependence of SA much stronger than that of SB. This is because glass (SA samples) is much more hydrophilic than clay (SB samples). As a result, SA rendered a stronger concentration gradient of the polar bitumen molecules in the film thickness direction than SB, thereby stronger negative bitumen content dependence. Diffusion coefficients were estimated using the cyclohexane initial uptake rates and the surface area average film thicknesses of the samples and were found that the diffusion coefficient increased with increasing bitumen content (i.e., film thickness) in both SA and SB cases. Varying fines content did not have any effect on the cyclohexane initial mass uptake rate. It was found that increase in the fines content decreased the bitumen film thickness, thereby decreasing the diffusion coefficient that is offset by the increase in the amount of cyclohexane dissolved at the interface.

Modori reaction in blue grenadier and Alaska pollock frozen surimi and myosin degradation behavior upon addition of protease inhibitors

ABSTRACT The changes in protein degradation behavior in fish surimi upon addition of different protease inhibitors were examined, with the aim of identifying the proteases involved in the modori reaction in different species and grades of fish and at different temperatures. The modori reactions at 40, 50, and 60°C in four frozen surimi samples: grades FA and KA blue grenadier and grades SA and RA Alaska pollock were investigated. In the grade FA blue grenadier surimi, the modori reaction primarily involved metalloproteases at 40°C, serine proteases and cysteine proteases at 50°C, and cysteine proteases at 60°C. The reaction in the grade KA blue grenadier surimi involved multiple proteases at 40°C, and metalloproteases and cysteine proteases at 50 and 60°C. In the Alaska pollock surimi, multiple proteases were suggested to be equally involved in the modori reaction at 40, 50, and 60°C in both grades SA and RA samples.

Study on the microstructure and creep behavior of Inconel 718 superalloy fabricated by selective laser melting

Horizontal-direction Inconel 718 alloy cylindrical rods were fabricated by selective laser melting (SLM) and subsequently subjected to solution or homogenization plus double aging (SA or HA) treatments. Lever arm creep tests were performed with the creep tensile axis perpendicular to the building direction of the samples with a constant stress of 650 MPa at 650 °C. Scanning and transmission microscopy and electron backscatter diffraction were used to clarify the microstructure of the SA and HA samples before and after creep. The experimental results revealed that the average grain sizes of the SA and HA samples were basically the same before creep, and larger γ′ and γ″ strengthening phases existed in the HA sample. The grains tended to grow, and the higher dislocation density within grains and lower local misorientation values close to the grain boundaries occurred in the HA sample during creep, which contributed to the longer creep rupture life in comparison with the SA sample. The fracture surfaces of the SA and HA samples displayed intergranular features, and the creep voids and micro-cracks were formed around the δ or Laves phases at the grain boundaries. The creep fracture mechanism was also discussed.

The false positive effect of residue of sulphur sources on dithiocarbamate analysis based on CS2 measurement

ABSTRACTTurkey plays an important role in the international trade of apricots as it has the largest production rate in the world. Since the sulphurisation process is allowed to be used for different products, the effect of residual sulphur and its compounds (which can be found in products as pesticide residues or additive residues) on the positive detection of carbon disulphide (CS2) still creates a big challenge in international trade. Therefore, the main objective of the present study was to investigate the effects of residues of sulphur or sulphur compounds on dithiocarbamate analysis methods based on CS2 measurement. In this study, apricots were chosen since they contain sulphur residues as a result of the sulphurisation process. Sulphur dioxide and dithiocarbamate analyses were conducted on dried apricots prepared with the sulphurisation process (SA) and without the sulphurisation process (NSA); analysis was by two different accredited laboratories. No of pesticide was applied to either SA or NSA samples. Although some of the NSA samples had <LOQ values, approximately 70 ± 32 mg/kg SO2 and 0.061 ± 0.021 mg/kg dithiocarbamate were detected for NSA samples. On the other hand, for the SA sample group, 927–2915 mg/kg of SO2 and 0.265–0.825 mg/kg of dithiocarbamate were detected. Furthermore, a strong correlation between residual sulphur and dithiocarbamate values was observed. This study showed that the analysis method based on CS2 measurement may lead to false positive results for dithiocarbamates when residues of sulphur or sulphur compounds are found in products as pesticide or additive residues. Therefore, residual sulphur compounds as a result of the sulphurisation process (which is not considered during the evaluation of products) must be taken into account during the evaluation of products for dithiocarbamates.

Basalt fiber fabric synergistically decorated by MnO2 nanosheets/stearic acid for the enhancement of oil-recovery and anti-icing behavior

Cross-weaved basalt fiber fabric (CBFF) woven from basalt fiber (BF), as a natural inorganic product, which presented a highly research value and widely application field, due to its high chemical stability, non-toxic, non-combustible and sound mechanical property. (Super)hydrophobic surface has recently received extraordinary attention, focusing both on novel preparation-used materials and application. In this work, cross-weaved basalt fiber fabric was synergistically decorated by MnO2 nanosheets/stearic acid (SA) and the superhydrophobic inorganic/organic composite (CBFF@MnO2/SA) was obtained by hydrothermal processes. MnO2 nanosheets self-assembled on the surface of CBFF (CBFF@MnO2) presented honeycomb roughness with the micro/nanometer-sized spaces among the MnO2 nanosheets. The water contact angles of CBFF, CBFF@MnO2 and CBFF@MnO2/SA samples were 21.6, 120.0 and 155.5°, respectively. The result indicated that cross-weaved basalt fiber fabric exhibited an obvious superhydrophobic property after the modification by MnO2 nanosheets and stearic acid. The as-prepared materials were applied in the simulation of oil/water separation and anti-icing process. Oil/water separation results not only displayed the separation efficiency up 95.0% by selective absorption for light oil/water system, but also showed the separation efficiency above 97.2% by filtration of oil for heavy oil/water system. Furthermore, CBFF@MnO2/SA could be used as the filter membrane in dynamic suction filtration device for oil recovery in oil spill accidents. Anti-icing experiments demonstrated that prepared CBFF@MnO2/SA had an obviously ice-over delay with the value of 166.6%.

Effect of heat treatment on microstructure evolution of Inconel 718 alloy fabricated by selective laser melting

Inconel 718 superalloy was fabricated by selective laser melting (SLM) and subsequently subjected to different heat treatments. Microstructure evolution was examined by X-ray diffraction, optical microscopy, scanning and transmission electron microscopies. In the horizontal section (normal to the building direction) of the as-built sample, columnar and cellular sub-structures formed in the overlapping area, while only cellular sub-structures existed in the central fusion area. Columnar structures were observed in the vertical section (parallel to the building direction). In the as-built condition, austenite γ and Laves phases predominated, almost to the exclusion of all other phases. When treated by the direct double aging (DA) process, δ-Ni3Nb phases precipitated mainly in the interdendritic regions where Nb preferentially segregated. Homogenization plus double aging (HA), and solution plus double aging (SA) treatments significantly eliminated microsegregation and Laves phases owing to the diffusion of Nb and Ti to the γ matrix. The δ phase dissolved in the HA-treated sample but precipitated in the SA-treated sample. The γ′-Ni3(Al,Ti) phase was prone to precipitate when treated by HA, while γ″-Ni3Nb phase tended to precipitate in the SA sample. Due to the precipitation of the higher fraction of the major strengthening γ″ phases, the SA sample showed the highest hardness value among the as-built, DA, HA, and SA samples. The morphology, distribution and crystallography of precipitates and their formation mechanisms are discussed and analyzed.

ELASTIC PROPERTIES AND STRUCTURAL OBSERVATIONS OF DISTALOY SA POWDER SINTERED WITH BORON AND CARBON

One of the methods aimed at increasing the density in PM parts is the process of activated sintering performed by adding boron as elementary boron powder, for example. Under this researchwork novel, PM materials were obtained based on prealloyed and diffusion bonded powder (type: Distaloy SA) with the following chemical composition: Fe-1.75%Ni-1.5%Cu-0.5%Mo, with the addition of 0.55 wt.% carbon and boron (0.2, 0.4 and 0.6 wt.%). Distaloy SA samples alloyed with carbon and boron were manufactured by mixing the powders in a Turbula mixer, then compacting the mixture in a hydraulic press under a pressure of 600 MPa and sintered in a tube furnace at 1473 K for 60 minutes in a hydrogen atmosphere. The densification process of Distaloy SA parts with boron and carbon depends on the sintering mechanism. In order to evaluate the sintering mechanism of the PM samples, structural investigations using SEM/EDS were performed. During sintering of these materials at 1473 K, a liquid phase is generated as a result of the reaction occurring between the alloy matrix and the complex of carbo-borides, which leads to a considerable degree of consolidation. The elastic properties of the sintered samples (such as Young’s modulus and the damping coefficient) were measured in a tensile test with a Forster elastometer.