Residual Liquid Research Articles

Comparison and investigation of edible hydrophobic coatings on beeswax and carnauba wax oil gels

In our daily life, it often uses all kinds of liquid food, such as cola, fruit juice and other drinks. Whenever you finish using these, you will find that there will inevitably be residual liquid at the bottom of the bottle that cannot be poured out, resulting in a considerable waste. However, in recent years, the emergence of lubricant infused surface (LIS) can be used to solve this problem. In this research, LIS is prepared by forming an oleogel with shellac and linseed oil, which has the advantage that the experimental raw materials require low cost, the materials are easily available, and do not cause health hazards to human beings. To gain a deeper understanding of the mechanism of LIS antifouling, the effects of optimal Brazilian carnauba wax content and beeswax content on the surface morphology, water contact angle and sliding angle, chemical functional groups, transmittance, and oil-holding rate of LIS were investigated, and the effects of liquid foodstuffs antifouling were tested with optimal Brazilian carnauba wax and beeswax content, respectively.

Simulation of gas porosity formation and interaction with dendrite and eutectic structures during solidification of Al-Si alloys

A two-dimensional (2-D) multi-phase cellular automaton (CA)-finite difference (FD)-lattice Boltzmann (LB) coupled model is developed to simulate the hydrogen pore formation during dendritic and eutectic solidification of hypoeutectic Al-Si alloys. In this model, the dendrite and eutectic structures are simulated using a CA technique. The solute diffusion is solved by the FD method. The nucleation, growth, and motion behavior of gas pore, and hydrogen transport are simulated by a LB Shen-Chen scheme. It is found that the pores can grow fully but compete in the primary dendrite growth stage. Conversely, pores newly nucleated in residual inter-dendrite liquid during the eutectic solidification stage grow restrictedly and independently. Pore shape severely deformed by the compression of the surrounding solid structures. Moreover, the effects of the initial Si composition, initial hydrogen concentration and cooling rate on the pore formation are qualitatively and quantitatively studied. It is found that the initial Si composition significantly impacts on the pore size and distribution, but little effect on the porosity percentage which decreases markedly with the decreasing initial hydrogen concentration and increasing cooling rate. Comparison reveals that the simulated microstructure morphological characteristics and the predicted porosity percentage agree well with the experimental observation reported in the literature.

Rapid dendritic growth kinetics of primary phase within supercooled Zr-V alloy at electrostatic levitation state

The liquid Zr100−xVx (x = 8.6, 16.5, 30) alloys were undercooled to the maximum undercooling of 364 K (0.18 TL), 405 K (0.21 TL), and 375 K (0.21 TL), respectively, by using electrostatic levitation technique. The Zr91.4V8.6 and Zr83.5V16.5 alloys present only one recalescence during liquid/solid phase transition, while the Zr70V30 alloy presents a transformation from two recalescence to one recalescence phenomenon with a critical undercooling of approximately 300 K. According to the LKT/BCT model, the calculated results of the primary β-Zr dendrite growth velocity in undercooled liquid Zr91.4V8.6 and Zr83.5V16.5 alloys agree well with the experiments. The velocity inflection points at 119 K of Zr91.4V8.6 alloy and 201 K of Zr83.5V16.5 alloy could be explained by the competition between solutal undercooling control and thermal undercooling control modes. For Zr70V30 alloy solidified in the P1 with twice recalescence, a critical second undercooling of 253 K and corresponding undercooling of 65 and 244 K are obtained. When the undercooling is in the range of 65–244 K, the second undercooling would be greater than 253 K, and the residual liquid phase would solidify into anomalous eutectic microstructure for Zr70V30 alloy. The Vickers hardness of Zr100−xVx (x = 8.6, 16.5, 30) alloys all show a quadratic relationship with undercooling. Under electrostatic levitation condition, the mechanical property of Zr-V alloys could be significantly regulated through solidifying the alloys at different undercoolings.

Inhibiting primary carbide in steel by diffusion: A perspective of phase-field study

This study provides a potentially viable approach to manipulate the precipitation of primary carbides in molten steel by modifying the diffusion coefficient of carbon. The solidification process of a Fe-C alloy is simulated using the multi-phase-field method, and we focus on the impact of diffusion coefficient of carbon on the solute segregation and cementite precipitation. Two benefits have been revealed as the ratio of the diffusivities of carbon in solid to that in liquid is increased. A potential advantage is the reduction in the volume fraction of the residual liquid enriched with carbon during the late solidification. Furthermore, the magnitude of the chemical driving force for the phase transition of cementite precipitation will be lower. The combined influence of both factors results in an exponential decrease in the volume fraction of cementite formed at the end of solidification.

Validation of the IDDSI funnel for liquid flow testing.

In 2017, the International Dysphagia Diet Standardisation Initiative (IDDSI) introduced the IDDSI flow test which enables patients, clinicians, caregivers, food service professionals and researchers to classify liquid thickness into five levels based on the volume of liquid remaining in a standard 10 mL slip tip syringe after 10 s of flow under gravity. Within a few months of publishing the IDDSI flow test instructions, several barriers emerged: (1) the preferred model of syringe (BD 303134) was not equally accessible around the world, causing some users to perform flow tests with alternate models of syringe; (2) differences in syringe geometry across models led to variations in IDDSI flow test results; and (3) the need to use a second syringe for sample loading added complexity and cost to end users. To address these barriers, IDDSI designed the IDDSI funnel, a novel device, which combines the geometry of the BD 303134 syringe with a kitchen funnel to facilitate easy loading of liquid samples without need for a second syringe. In this report, we compare the IDDSI flow test results across two devices: syringe BD 303134 and IDDSI funnel. IDDSI level classifications were in complete agreement with the syringe reference test results in 67/73 (92%) of the test fluids and temperature conditions with mean difference of residual liquid across devices of 0.2 (2% full scale). These results demonstrate excellent correspondence between the two devices.

Mechanism of improving solidification structure of super austenitic stainless steel by feeding strip into molten steel

Feeding steel strip into molten steel is an effective technique for refining the solidification structure of steel, especially for high-alloy steel. This study experimentally and numerically investigated the effects of feeding strip on the solidification structure of super austenitic stainless steel S32654. The results revealed that feeding strip noticeably increased the proportion of equiaxed grains, refined the dendritic structure, and improved Mo segregation and the precipitation of σ phase. The relevant mechanism was clarified as follows. Firstly, feeding strip promoted the formation and survival of a large number of floating dendrites by cooling the molten steel. As the temperature decreased, these floating dendrites sharply increased their quantity by repeated splitting and then acted as nucleation particles. Numerous equiaxed grains grew around these floating dendrites, significantly refining the central dendritic structure. Meanwhile, the doubling of the equiaxed grains has two effects on Mo segregation. First, it prevented the growth of columnar grains and the movement of Mo segregation interface towards the center, thus reducing the Mo macrosegregation. On the other hand, it dispersed and refined the residual liquid phase (Mo segregation regions), thereby reducing the Mo microsegregation. Additionally, the reduced Mo segregation lowered the σ phase precipitation temperature, allowing it to form in solid austenite with a shortened growth duration. The lighter Mo segregation and slower Mo diffusion in solid austenite led to insufficient Mo supply for the σ phase growth. Moreover, dendritic refinement limited the growth space of the σ phase. Finally, less and finer σ phase particles precipitated in the S32654 steel fed with strip. The improvement of feeding strip on the solidification structure will reduce the temperature and time required for high-temperature homogenization, which is beneficial for the subsequent hot working.

Highly Conductive Doped Fluoride Solid Electrolytes with Solidified Ionic Liquid to Enable Reversible FeF3 Conversion Solid State Batteries

AbstractSolid‐state lithium metal batteries based on fluorinated solid electrolytes have attracted attention due to their safety and stability advantages. However, the fluoride solid electrolytes face the problem of relatively low Li‐ion conductivity due to the lacking of suitable structural prototypes and their corresponding modulation modes. In this work, a chlorine‐doped fluoride solid electrolyte Li3AlF5.87Cl0.13 is developed with high ionic conductivity by thermal fluorination and weak chlorination of mixed ionic liquids. The Cl anion is doped into the cryolite‐like open framework structure, and the electrolyte particle boundaries are decorated by solidified thin‐layer (≈2 nm) ionic liquid. Both the bulk and interface modifications enable the improvement of Li‐ion conductivity to 2 × 10−4 S cm−1 at 30 °C, which is the highest level among fluoride solid electrolytes. The Li3AlF5.87Cl0.13 with residual solidified ionic liquid shows the excellent stability of interface contact with Li metal, and the corresponding Li symmetric cell exhibits a small overvoltage (≈100 mV) with outstanding cycle life (at least 500 h). For the first time, a conversion‐type solid‐state Li/FeF3 battery is developed based on this fluoride electrolyte, delivering a reversible capacity as high as 430 mAh g−1. The existence of natural F‐rich interface promotes the conversion reaction reversibility of FeF3 cathode.

Petrogenesis of the Early Paleogene North Island Syenite Complex, Seychelles

The Early Paleogene (63.65 ± 0.52 Ma, 63.11 ± 0.45 Ma) North Island syenitic complex of the Seychelles microcontinent is composed principally of diorite (SiO2 ≈ 57 wt%), syenite (SiO2 = 61–65 wt%), and microsyenite (SiO2 = ∼70 wt%). The rocks are metaluminous, ferroan, and alkalic, and are compositionally similar to the A1-type granitoids. The trace element compositions of the syenitic rocks show minor spatial variability between the eastern (Congoment, Bernica) and western portions (Grand’Anse, Mt. Des Cèdres) of the island. The whole rock Sr-Nd (87Sr/86Sri = 0.704095–0.707533; εNd(t) = +1.2–+1.9) and zircon Hf ( εHf(t) = +2.1–+8.4) isotopes are indicative of a juvenile magma source. The low Th/NbPM (0.3–1.5) and high Nb/U (30.9–109) ratios do not indicate a crustal origin of the rocks nor do they suggest crustal contamination was significant. Hydrous fractional crystallization modeling shows that a mafic alkaline parental magma can yield residual liquid compositions similar to the diorites and syenites under reducing conditions ( ΔFMQ = −1) at a pressure of 0.3 GPa. However, feldspar accumulation likely occurred as some rocks have elevated Eu/Eu* (>1.1) values. The emplacement of the North Island complex is contemporaneous with the eruption of the Deccan Traps and rifting of the Seychelles microcontinent from India. Rifting and magmatism was likely related to the passage of the Indian plate over the Réunion hotspot. The modeling results of the study demonstrate that crystallization pressure has an influence on whether basalt-derived A-type granitoids will evolve to metaluminous or peralkaline compositions.

Effect of additive content on texture evolution and mechanical properties of Si3N4 ceramics prepared by hot pressing

The purpose of this research is to investigate influence of additive content on sintering behavior, texture evolution and mechanical properties of Si3N4 ceramics systematically. Si3N4 ceramics with different additive contents are prepared by hot pressing at 1750 °C for 1h. XRD analysis confirms that the densification process is dominated by particle rearrangement instead of phase transformation. Grain morphology characterization demonstrates that additive content affects relative amount between textured β-Si3N4 grains and β-Si3N4 nuclei during initial sintering. During subsequent sintering, β-Si3N4 nuclei surrounded by residual liquid phase elongated randomly, and then weaken texture degree of Si3N4 ceramics. The texture degree of Si3N4 ceramics decreases first and then increases as additives increase steadily. Based on the CTE misfit model and the stochastic model of crack propagation, texture degree, residual stress and grain size have a synergistic effect on crack propagation behavior of β-Si3N4 ceramics. The outstanding flexural strength (1096 MPa) and fracture toughness (10.61 MPa ∙ m1/2) is achieved in hot pressed SN21 with a relatively high texture degree (fL = 0.213).

Investigating the effect of anchoring groups modified comb-like polycarboxylate hyperdispersants on dispersion and stability in dispersed dyes

Comb-like hyperdispersants are widely used for the dispersion of liquid dispersed dyes (LDDs), because of the molecular structure of comb, in which the effective steric hindrance effects provided by polymer side chains and the adsorption force provided by anchoring groups, resulting in the dispersant to be firmly adsorbed on the surface of the dye. However, the mechanism by which the anchoring groups in this dispersant affect the dispersion and stability of LDDs is still unclear. Herein, three types of anchoring group modified comb-like polycarboxylate hyperdispersants were synthesized to explore the effect of anchoring groups on stability and dispersibility, in which the anchoring groups from the monomers of 2-vinylnaphthalene (2-VNP), styrene (St), and 4-vinylbiphenyl (4-VBP). The optimal sand grinding conditions and dispersion stability of the modified hyperdispersants were comprehensively investigated. 2-VNP modified hyperdispersant (DPN) possessed higher grinding efficiency and better dispersion stability than those of St (DPS) and 4-VBP modified hyperdispersants (DPB). The results of atomic force microscope (AFM) and quartz crystal microbalance (QCM) indicated that DPN exhibited higher adsorption force (2.16 mN/m) than that the DPS (0.648 mN/m) and DPB (1.56 mN/m), thereby improving the adsorption strength of dispersants and DDs, stabling the dispersion effect of LDDs. In addition, the dyeing performance of the prepared LDDs on polyester fabric was further investigated. It was found that these LDDs acquired a faster dyeing rate, higher K/S values and rubbing color fastness, and lower chemical oxygen demand (COD) of residual liquid than commercial powder DDs, due to the higher adsorption force on the DDs surface provided good colloidal stability in the high temperatures dye bath. We expect that this study will provide important mechanistic insights into the development of hyperdispersants for LDDs controlled by high adsorption force anchoring groups.

A novel method for evaluating solidification cracking susceptibility of austenitic stainless steel using trapezoidal hot cracking test during laser welding

A novel evaluation method was developed for evaluating solidification cracking susceptibility of austenitic stainless steel using trapezoidal hot cracking test laser welding. By changing different chemical compositions and welding speeds, the critical restraint width was named and regarded as a new index to evaluate cracking susceptibility. First of all, the average critical restraint width of SUS310S, 316 and 302 was measured as 22.97 mm, 18.17 mm and 17.38 mm during laser welding at a speed of 1.0 m/min, respectability. Single phase austenite under mode A appeared in 310S while the other could form austenite and a small amount of ferrite based on mode FA, therefore, the solidification cracking susceptibility was 310S > 316 > 302. Then, the critical restraint widths of SUS310S and 304 had a tendency of decrease with increasing welding speed from 0.5 m/min to 1.0 m/min during laser welding. The lower heat input could decrease primary and secondary dendrite arm spacings, causing a reduction in the segregation degree. In addition, the fine dendrite along grain boundary of weld center could contribute to form zigzag interface which would be beneficial to interrupt the continuous residual liquid film. Thus, the solidification cracking susceptibility tended to decrease with an increase in laser welding speed from 0.5 m/min to 1.0 m/min. Above all, the developed evaluation method could improve the applicability, feasibility and progressiveness of hot cracking test.

Research on gas pore formation and inhibition mechanism of high nitrogen steel during laser direct metal deposition

Nitrogen pore formation is an inherently tricky problem that limits the application of high nitrogen steel (HNS) in various fields. In the present study, a CA-LBM coupling model was proposed to understand the nitrogen pore formation mechanism during laser direct metal deposition (DMD) of HNS. Based on the proposed model and theoretical analysis, the effects of pulse frequency and shielding gas nitrogen content on the porosity were clarified systematically. Results showed that after the onset of solidification, the ferrite phase with extremely low nitrogen solubility precipitated first, inducing the continuous enrichment of nitrogen in the residual liquid phase, which in turn provided the prerequisite for nitrogen pore nucleation. The application of quasi-continuous-wave (QCW) laser mode accelerated the molten pool solidification, and shortened the nitrogen supersaturated region, allowing more nitrogen to be solid dissolved in the matrix. On this basis, the porosity was inhibited to a certain extent. Compared with the high-frequency pulse, the low-frequency pulse showed better porosity inhibition. In addition, following the classic nucleation theory, nitrogen segregation and nitrogen solubility synergistically dominated nitrogen pore formation. The nitrogen partial pressure, determined by the shielding gas nitrogen content, played a dual role in porosity defects. Elevated nitrogen partial pressure served to increase nitrogen solubility while promoting the nitrogen absorption process to intensify nitrogen segregation. However, due to the short duration of the molten pool, the nitrogen absorption process could not be fully processed. Nitrogen solubility enhancement was the key factor in inhibiting porosity during the DMD process.

Formation mechanism of (Ti, Zr, Hf)C medium-entropy carbide derived from polymer precursors and its modification on the ablative mechanism of C/C-SiC composites

Medium-entropy carbide (MEC) of (Ti, Zr, Hf)C was synthesized and its modification on the ablative mechanism of C/C-SiC composites was investigated. After 60 s oxyacetylene flame test, the mass and linear ablation rates were 1.43 mg/s and 11.1 μm/s, respectively. The evolution of ceramics oxide scale dominated the anti-ablation process, which transfers from (Ti, Zr, Hf)xCyOz, (Ti, Zr, Hf)xSiyOz to (Ti, Zr, Hf)O2, (Zr, Hf)TiO4. With further evaporation of SiO2, the generated (Ti, Zr, Hf)O2 skeleton and the residual liquid oxides ((Zr, Hf)TiO4 and (Zr, Hf)SiO4) can block the oxygen channel and further reduce oxidation of the inner matrix.

Factors affecting the rumen fluid foaming performance in goat fed high concentrate diet.

Feeding high concentrate diets is highly prone to rumen bloat in ruminants, which is very common in production. This study explored the factors responsible for the occurrence of foamy rumen bloat. The experiment was conducted using goats as test animals, fed high concentrate diets and scored for rumen distension into high, medium and low bloat score groups. Rumen fluid was collected from 6 goats in each group separately. The foaming production, foam persistence, pH value, viscosity and the content of protein, total saccharide and mineral elements in rumen original fluid (ROL) were measured, and the protein and total saccharide content in rumen foam liquid (RFL) and rumen residual liquid (RRL) were determined. The results showed that the protein content in rumen original fluid and rumen foam liquid was significantly higher than that in rumen residual liquid (p < 0.05), and the protein content in rumen foam liquid was 10.81% higher than that in rumen original fluid. The higher the rumen bloat score, the higher the foam production, foam persistence, viscosity, protein, Ni, Mg, Ca, and K concentrations of the rumen original fluid, and the lower the PH and Na concentrations of the rumen original fluid; correlation analysis showed that the viscosity of the rumen original fluid was significantly and positively correlated with the foam production and foam persistence (p < 0.05). Foaming production and foam persistence of rumen original fluid were significantly and positively correlated with the contents of protein, total saccharide, K, Ca, Mg and Ni (p < 0.05). and negatively correlated with the content of Na (p < 0.05); after controlling other components those were significantly related to the foaming performance of rumen original fluid only protein still was significantly positively correlated with the foam persistence of rumen original fluid (P<0.05). In summary, the contents of protein, total saccharide and mineral elements in the rumen fluid had a significant effect on the foaming performance of rumen in ruminants, with protein playing a decisive role and the other components playing a supporting role. Reducing the content of protein in the diet in production is beneficial to reduce the occurrence of rumen bloat in ruminants.

Thermocapillary migration of a droplet on a substrate with wettability difference: A comparison between slip and precursor film models in three dimensions

Moving contact line dynamics calculations include two models: precursor film models and slip models. The lubrication approximation method is used to establish a three-dimensional mathematical model to analyze the droplet thermocapillary migration behavior on a non-uniformly heated solid substrate with a wettability track. The contact line dynamics in the slip model and the disjoining pressure effect in the precursor model are proposed to regulate the substrate wettability. Both models are numerically implemented to investigate droplet spreading for three cases: free spreading on an isothermal substrate, thermocapillary migration on a uniform wettability substrate, and thermocapillary migration on a wettability-confined track. For the case of free spreading on an isothermal substrate, the three-dimensional results of the slip and precursor contact line models are essentially consistent with two-dimensional slip model results. For the case of thermocapillary migration on a uniform wettability substrate, the results of the two models essentially agree with the experimental results. Decreasing the thermal gradient reduces the discrepancies between the two models that result from the coordinate transformation method used in the slip model, which reduces the contact angles measured in the y-direction and enlarges the advancing contact angle in the migration direction. For the case of thermocapillary migration on a wettability-confined track, the slip model gradually shows a “dynamic-pinning” behavior with increasing equilibrium contact angle in the hydrophobic region. By contrast, the precursor film model maintains a stationary pinning behavior but separates a residual liquid outside the track. The precursor film model is preferred over the slip model in lubrication approximations for three-dimensional fluids when calculating complex moving contact dynamics caused by wettability differences. However, the precursor film model must be further optimized to prevent numerical instability.

Hot Tearing Susceptibility and Solidification Behavior of Mg-xGd-(4-x)Y-2Ni-0.5Zr Alloys

The hot tearing susceptibility (HTS) of Mg-xGd-(4-x)Y-2Ni-0.5Zr (x = 0, 1, 2, 3, 4, wt%) alloys was evaluated using a T-shape mold method. When the Gd element increased and the Y element decreased, the HTS of the alloys decreases gradually. The Mg-4Y-2Ni-0.5Zr has the highest while Mg-4Gd-2Ni-0.5Zr has the lowest HTS value. Microstructure observation reveals that the grains of the magnesium alloy were refined to a certain extent when the Gd element increased and the Y element decreased. The ‘pinning’ effect of the LPSO phase precipitated along the grain boundary effectively increases the solid skeleton strength of the alloy and reduces the HTS of the magnesium alloy to a certain extent. The thin and uniform liquid film at the fracture can disperse the solidification shrinkage stress. In addition, the binary phase precipitated in the alloy forms a fast channel of residual liquid phase feeding on the liquid film, which is beneficial to feeding hot cracks. Solidification behavior of the alloys by thermal analysis showed that with the increase of the Gd element and the decrease of the Y element, the dendrite coherency temperature of the dendrites of the alloy decreases, and the residual liquid phase feeding is easier. The solid fraction of dendrite coherency increases, the skeleton strength of the alloy increases, and the HTS of the alloy decrease. In Mg-xGd-(4-x)Y-2Ni-0.5Zr (x = 0, 1, 2, 3, 4, wt%) alloys, when x is 1, 2, 3, 4, the HTS of the alloy is reduced by 25%, 49%, 63%, 81%, respectively compared with that when x is 0.

Fractionation of iron and titanium isotopes by ilmenite and the isotopic compositions of lunar magma ocean cumulates

Basaltic volcanism on the Moon produced low- and high-Ti mare basalt suites that are also distinct with respect to their iron, titanium, and magnesium isotopic compositions. Here, the equilibrium fractionation of Fe and Ti isotopes between ilmenite and melt was experimentally investigated in order to evaluate the role of ilmenite in generating the isotopic compositional variability among the lunar mare basalts. Ilmenite crystallization experiments were conducted using two bulk compositions: an ilmenite-saturated basaltic andesite and an ilmenite-saturated Apollo 14 black glass, and the Fe and Ti isotopic compositions of the experimental ilmenites and glass (quenched melt) were analyzed using solution MC-ICPMS after hand-picking. Additionally, Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements on synthetic ilmenite were conducted and compared to previous NRIXS measurements on synthetic lunar glasses in order to derive temperature-dependent equilibrium ilmenite-melt Fe isotopic fractionations. Experimentally determined ilmenite-melt fractionations were then incorporated into a lunar magma ocean crystallization model that tracks the major element and isotopic compositional evolution of lunar magma ocean cumulates and residual liquid. There is good agreement between the Fe equilibrium isotopic fractionation measured by NRIXS and the laboratory equilibration experiments, and we find that the isotopic fractionation is sensitive to ilmenite compositional differences (0 vs. 10% Fe3+). Further, the light Ti isotopic composition of ilmenite relative to the melt (Δ49Ti=ilmenite-melt−0.09±0.03‰ at 1100∘C) is consistent with the higher coordination of Ti in ilmenite relative to melts and results of previous studies. The modeled Ti isotopic compositions for lunar magma ocean cumulates display Ti isotopic variability sufficient to explain the low- and high-Ti mare basalt sources. However, the difference in Fe isotopic composition between the low- and high-Ti mare basalts cannot be attributed solely to ilmenite fractionation. Instead, Fe isotopic fractionation by additional products of lunar magma ocean crystallization, such as clinopyroxene, is required to generate the inferred Fe and Mg isotopic variability in the lunar mantle. Alternatively, the Fe and Mg isotopic compositions of the lunar mare basalts may indicate Fe-Mg interdiffusion has occurred in the Ti-rich component of the mare basalt source regions via reaction between ilmenite cumulates and the olivine- and pyroxene-rich lunar mantle.

A novel prediction model of the freckle defects for single-crystal superalloy blades

The freckle is a typical surface defect formed during the directional solidification of SC (single crystal) components of Ni-based superalloys. It generally appears as a long and narrow trail of equiaxed grains aligned roughly parallel to the direction of gravity, which breaks the integrity. Once appears, the freckle can never be avoided by further treatment. With the turbine blade requirements increasing, the state-of-the-art methods include adding more refractory elements into Ni-based SC superalloys, and the design of blades with a more complex geometric shape make the freckle defects grow easier at the special surface zones. This leads to a significant challenge in controlling grain defect formation in SC blades and vanes for freckles. The current consensus to freckle formation is described as the Rayleigh-Taylor instability (RTI) flow that occurred in the interdendritic zone. During solidification, the compositional segregation (CS) occurred as soon as the solid interface forwarding led to the density changes between the interdendritic melting phases and the residual liquids. For nickel-based superalloys, the enrichment of low-density solutes like Al, and Ti at the interdendritic zone will make the liquid lighter. However, the widely used Ra model can’t correctly match the freckle tendency of the components with complex shapes (called geometrical effects of freckles), especially for blades. Recent reports indicate that the freckles occur at the preferred positions in the casting. In this work, a novel model is designed to quantitatively discuss the geometrical effects on freckle formation and to combine existing Ra number models with solidification models to enable freckle predictions at a smaller scale. The proceeding of this work can make the design of complex blades easier.

Ionic-liquid-tolerant enzymes from an adapted Bacillus paralicheniformis for one-pot conversion of lignocellulosic substrates to ethanol

A newly isolated thermophilic cellulase-producing Bacillus paralicheniformis was subjected to adaptive laboratory evolution in the presence of increasing concentration (from 1 to 5% w w−1) of an otherwise toxic ionic liquid (either 1-ethyl-3-methylimidazolium chloride, or 1-butyl-3-methylimidazolium chloride) over 200-days to obtain strains that produced ionic-liquid-stable enzymes. The ability of the ionic-liquid-adapted strains to grow and produce cellulose hydrolyzing enzymes was proven using several different untreated agroindustrial lignocellulosic substrates. The cellulase of the adapted isolate retained more than 99% of its initial activity after incubation (12 h, ∼25 °C) with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]; 50% w w−1 concentration of ionic liquid). In contrast, the wildtype cellulase retained < 9% of its initial activity after an equivalent exposure to a lesser concentration (15% w w−1) of the ionic liquid. Using untreated sugarcane bagasse as the substrate, the optimal conditions for producing the ionic-liquid-stable enzymes (cellulase, xylanase, β-glucosidase) by the adapted bacterium were 48 °C and an initial pH ∼6. The ionic-liquid-adapted crude enzymes were used in a one-pot process (at 50 °C, 48 h) to release glucose from the ionic-liquid-pretreated wheat straw (pretreatment at 90 °C, 1 h, using 10% (w w−1) wheat straw in [Emim][Ac]), in the presence of the residual ionic liquid. At 48 h of enzymolysis, the glucose concentration exceeded 50 g L−1. This glucose mixed with the residual ionic liquid was fermented (24 h, 37 °C) to ethanol using the conventional yeast Saccharomyces cerevisiae. The ethanol yield on glucose was nearly 56% of the theoretical maximum, despite the yeast not having been adapted to withstand the toxic ionic liquid.

Determination of Sodium Sulfate Requirement for Obtaining Sodium Sulfide Content in Green Liquor at the Recovery Boiler Unit in PT XYZ North Sumatra

Black liquor is a residual cooking liquid containing organic chemicals utilized as fuel in the recovery boiler and inorganic chemicals that can be recovered into cooking liquid through the recovery boiler process. The recovery boiler is a specialized boiler unit used to restore black liquor by reducing sodium sulfate into sodium sulfide. The research method involved field observations, liquor content analysis, and stoichiometric calculations to determine the sodium sulfate requirement. The calculations revealed that the sodium sulfide content obtained from the recovery boiler process in green liquor was 24.428 g/l Na2O, requiring a reactive amount of 46,5225.0328 kg/day of sodium sulfate. The target sodium sulfide content in the green liquor aimed for was 18-30 g/l. The results indicated that the sodium sulfide content has met the predetermined target and can be utilized for subsequent processes.