Preventing formation of intermetallic compounds in ultrasonic-assisted Sn soldering of Mg/Al alloys through pre-plating a Ni coating layer on the Mg substrate

Magnesium and aluminum alloys are widely used in various industries because of their excellent properties,and their reliable connection may increase application of materials.Intermetallic compounds(IMCs)affect the joint performance of Mg/Al.In this study,AZ31 Mg alloy with/without a nickel(Ni)coating layer and 6061 Al alloy were joined by ultrasonic-assisted soldering with Sn-3.0Ag-0.5Cu(SAC)filler.The effects of the Ni coating layer on the microstructure and mechanical properties of Mg/Al joints were systematically investigated.The Ni coating layer had a significant effect on formation of the Mg_(2)Sn IMC and the mechanical properties of Mg/Al joints.The blocky Mg_(2)Sn IMC formed in the Mg/SAC/Al joints without a Ni coating layer.The content of the Mg_(2)Sn IMC increased with increasing soldering temperature,but the joint strength decreased.The joint without a Ni coating layer fractured at the blocky Mg_(2)Sn IMC in the solder,and the maximum shear strength was 32.2 MPa.By pre-plating Ni on the Mg substrate,formation of the blocky Mg_(2)Sn IMC was inhibited in the soldering temperature range 240–280℃and the joint strength increased.However,when the soldering temperature increased to 310℃,the blocky Mg_(2)Sn IMC precipitated again in the solder.Transmission electron microscopy showed that some nano-sized Mg_(2)Sn IMC and the(Cu,Ni)_(6)Sn_(5)phase formed in the Mg(Ni)/SAC/Al joint soldered at 280℃,indicating that the Ni coating layer could no longer prevent diffusion of Mg into the solder when the soldering temperature was higher than 280℃.The maximum shear strength of the Mg(Ni)/SAC/Al joint was 58.2 MPa for a soldering temperature of 280℃,which was 80.7%higher than that of the Mg/SAC/Al joint,and the joint was broken at the Mg(Ni)/SAC interface.Pre-plating Ni is a feasible way to inhibit formation of IMCs when joining dissimilar metals.

Adenosine cyclic phosphate with ultrasonic-assisted pectinase extraction alleviated allergic reactions in RBL-2H3 through inhibiting the influx of intracellular Ca^(2+)

Jujube contains abundant cyclic adenosine monophosphate(cAMP)and the ultrasonic-assisted pectinase extraction(UAPE)conditions for obtaining the maximum cAMP yield from jujube were optimized.Orthogonal array design was applied to evaluate the effects of 4 variables by UAPE on cAMP yield.The results showed that the optimal cAMP yield(783.0μg/g)was derived at ratio of liquid to solid 5 mL/g,ratio of pectinase to raw material 1.5%,time 60 min and temperature 40℃.Moreover,the effect of cAMP on the anti-allergic function of action induced by immunoglobulin E(IgE)and its meschanism was investigated through establishing the sensitized cell model in rat basophilic leukemia(RBL-2 H3)cells using dinitrophenylated(DNP)-bovine serum albumin(BSA)-IgE.The results showed that cAMP interfered with sensitized cells,effectively inhibited the occurrence of basophil degranulation in dose dependence,and significantly reduced the activity ofβ-hexosamindase(β-hex),at the optimal concentration of 50μg/mL.The level of anti-inflammatory factor interleukin-10(IL-10)was promoted and the content of pro-inflammatory factor tumor necrosis factor-α(TNF-α)was suppressed by cAMP.In addition,influx of intracellular Ca^(2+) was repressed effectively.Our results demonstrate that jujube cAMP regulated the cytokine balance in the allergy pathway through blocking the influx of extracellular Ca^(2+),with the prevention of allergy symptoms.

Antioxidant and hepatoprotective effects of Ajuga nipponensis extract by ultrasonic-assisted extraction

Objective: To investigate suitable condition for extraction of the active components from Ajuga nipponensis(A. nipponensis). Methods: Orthogonal experimental design was used to determine the optimal extraction parameters for ecdysterones and flavonoids. Finally, the hepatoprotective abilities of A. nipponensis extracts were evaluated by CCl_4-induced animal models. Results:Maximum yields of flavonoids(7.87±0.10) mg/g and ecdysterones(0.73±0.02) mg/g could be obtained when the extraction time was 50 min, the extraction temperature was 60 ℃, and the ratio of sample to 70%(v/v) ethanol was 1:20(w/w). The antioxidant property of A. nipponensis was correlated to the concentration of its extracts. At 5 mg/m L, A. nipponensisextract scavenged 84.8% of DPPH radical and had absorbance values of 2.43±0.04 reducing power. Upon CCl_4-induced liver injury, glutamic oxaloacetic transaminase and glutamic pyruvic transaminase decreased significantly after the mice were treated with A. nipponensis. Histological researches also explained that A. nipponensis reduced the extent of liver lesions induced by CCl_4. Conclusions: A. nipponensis exhibited potent antioxidant activity in chemical experimental models and hepatoprotective effect against CCl_4-induced liver damage.

Optimization of Ultrasonic-Assisted Extraction Process of Polysaccharides from American Ginseng and Evaluation of Its Immunostimulating Activity

Ultrasonic-assisted extraction （UAE） of American ginseng polysaccharides （AGP） was investigated using response surface methodology. Three-factor-three-level Box-Behnken design was employed to optimize the ultrasonic power, extraction time and ratio of water to raw material to obtain a high AGP yield. The analysis of variance and response surface plots indicated that ultrasonic power was the most important factor affecting the extraction yield. The optimal conditions were ultrasonic power 400 W, extraction time 71 min, and ratio of water to raw material 33 mL g-1. Under these conditions, the yield of AGP was 8.09%, which was agreed closely to the predicted value. Gas chromatography （GC） analysis showed that AGP was composed of arabinose, rhamnose, galactose, glucose, and galacturonic acid. Fourier transform infrared spectra revealed the general characteristic absorption peaks of AGP. In addition, AGP exhibited good immunostimulating activities by up-regulating the production of nitric oxide and cytokines. Compared with hot water extraction, UAE required shorter extraction time and gave a higher extraction yield, without changing the structure and immunostimulating activity of AGP. The results indicated that UAE could be an effective and advisable technique for the large scale production of plant polysaccharides.

Force Modeling for Ultrasonic-assisted Wire Saw Cutting SiC Monocryatal Wafers

The advantages, such as a small cutting force, narrow kerf and little material waste make wire saw cut- ting suitable for machining precious materials like SiC, Si monocrystal and a variety of gem. As regards wire saw cutting fo wafer, however, in traditional wire saw cutting process, the cutting efficiency is low, the wear of wire saw is badly, the surface roughness of wafer is poor etc, which have a seriously impact on the cutting process stability and the use of wafers. Ultrasonic-assisted machining method is very suitable for processing a variety of non-conduc- tive hard and brittle materials, glass, ceramics, quartz, silicon, precious stones and diamonds, etc. In this paper, the force model of ultrusonic-assisted wire saw cutting of SiC monocrystal wafer, based on the kinematic and experi- mental analysis were established. The single factor and orthogonal experimental scheme for different processing pa- rameters such as wire saw speed, part rotation speed of and part feed rate, were carried out in traditional wire saw and ultrasonic-assisted wire saw cutting process. The multiple linear regression method is used to establish the static model among the cutting force, processing parameters and ultrasonic vibration parameters, and the model signifi- cance is verified. The results show, as regards ultrasonic-assisted wire saw cutting of SiC monicrystal wafer, both the tangential and normal cutting forces can reduce about 24. 5%-36% and 36. 6%-40%.

Enhanced thermal- and impact-initiated reactions of PTFE/Al energetic materials through ultrasonic-assisted core-shell construction

A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al (CS-PA) energetic materials through ultrasonic-assisted mixing. The low-cost micrometer-sized PTFE and Al particles were used as starting materials. Under high-power ultrasonic waves, the PTFE powder was dispersed into nano-to sub-micrometer-sized particles and then encapsulated the Al microparticles to form the core-shell structure. The heat of combustion, burning rate, and pressurization rate of the powdered CS-PA were measured. The thermal-initiated reaction behavior was further evaluated using thermogravimetry-differential scanning calorimetry. Subsequently, the bulk CS-PA with a uniform microstructure was obtained via cold isostatic pressing of the powdered CS-PA followed by vacuum sintering. For the bulk CS-PA, the quasi-static compression behavior was characterized, and the impact-initiated reaction processes were conducted using the Split Hopkinson Pressure Bar (SHPB) and evaluated by a high-speed camera. Compared to physically mixed PTFE/Al materials, the powdered and bulk CS-PA demonstrated enhanced thermal- and impact-initiated reaction characteristics respectively, proving the effectiveness of our approach for constructing core-shell structures.

Optimization of ultrasonic-assisted enzymatic extraction of flavonoids from the fruit oiAronia melanocarpa

As a new resource food,Aronia melanocarpa is rich in flavonoids,which has a broad development prospect.In order to obtain a higher extraction rate of flavonoids,cellulase was used to extract total flavonoids from the fruits of Aronia melanocarpa by ultrasonic-assisted enzymatic extraction(UAEE).The extraction process was optimized by single factor experiment and orthogonal experiment.The optimum conditions were as follows:enzymatic hydrolysis time 2.0 h,enzymatic hydrolysis temperature 37℃,enzyme content 0.5%(by weight of fruit pulp),ethanol concentration 90%,solid-liquid ratio 1:20,enzymatic hydrolysis temperature 37℃,enzymatic hydrolysis temperature 37℃,enzyme content 0.5%(by weight of fruit pulp),ethanol concentration 90%.Ultrasonic extraction time 1,0h,temperature 45℃.Under the above conditions,the extraction yield of flavonoids reached 1.455 mg/g.Compared with ultrasonic-assisted extraction(UAE),the extraction yield was significantly improved.Therefore,ultrasonic-assisted enzymatic hydrolysis is an effective method for the extraction of total flavonoids hom Aronia melanocarpa.

Novel model of material removal rate on ultrasonic-assisted chemical mechanical polishing for sapphire

Ultrasonic-assisted chemical mechanical polishing(UA-CMP)can greatly improve the sapphire material removal and surface quality,but its polishing mechanism is still unclear.This paper proposed a novel model of material removal rate(MRR)to explore the mechanism of sapphire UA-CMP.It contains two modes,namely two-body wear and abrasive-impact.Furthermore,the atomic force microscopy(AFM)in-situ study,computational fluid dynamics(CFD)simulation,and polishing experiments were conducted to verify the model and reveal the polishing mechanism.In the AFM in-situ studies,the tip scratched the reaction layer on the sapphire surface.The pit with a 0.22 nm depth is the evidence of two-body wear.The CFD simulation showed that abrasives could be driven by the ultrasonic vibration to impact the sapphire surface at high frequencies.The maximum total velocity and the air volume fraction(AVF)in the central area increased from 0.26 to 0.55 m/s and 20%to 49%,respectively,with the rising amplitudes of 1–3μm.However,the maximum total velocity rose slightly from 0.33 to 0.42 m/s,and the AVF was nearly unchanged under 40–80 r/min.It indicated that the ultrasonic energy has great effects on the abrasive-impact mode.The UA-CMP experimental results exhibited that there was 63.7%improvement in MRR when the polishing velocities rose from 40 to 80 r/min.The roughness of the polished sapphire surface was R_(a)=0.07 nm.It identified that the higher speed achieved greater MRR mainly through the two-body wear mode.This study is beneficial to further understanding the UA-CMP mechanism and promoting the development of UA-CMP technology.

Recent advances in ultrasonic-assisted machining for the fabrication of micro/nano-textured surfaces

In this paper, the state of art of ultrasonic- assisted machining technologies used for fabrication of micro/nano-textured surfaces is reviewed. Diamond machining is the most widely used method in industry for manufacturing precision parts. For fabrication of fine structures on surfaces, conventional diamond machining methods are competitive by considering the precision of structures, but have limitations at machinable structures and machining efficiency, which have been proved to be partly solved by the integration of ultrasonic vibration motion. In this paper, existing ultrasonic-assisted machin- ing methods for fabricating fine surface structures are reviewed and classified, and a rotary ultrasonic texturing （RUT） technology is mainly introduced by presenting the construction of vibration spindles, the texturing principles, and the applications of textured surfaces. Some new ideas and experimental results are presented. Finally, the challenges in using the RUT method to fabricate micro/ nano-textured surfaces are discussed with respect to texturing strategies, machinable structures, and tool wear.

Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology

Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.Materials and Methods:Three independent and major variables were selected,including initial ultrasonic temperature(℃),ultrasonic power(W)and ultrasonic time(s on/2 s off).On the basis of one-factor experiments,17 groups of experiments were established by response surface methodology according to Box-Behnken design.Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation,which was tested by proper statistical methods.Results:The optimal ultrasonic conditions were as follows:initial ultrasonic temperature 0℃,ultrasonic power 180 W,ultrasonic time 5 son/2 s off.Under the optimization conditions,the time of passing through maximum ice crystal generation zone was 105.500 s,which was very close to the predictive passage time of 101.541 s.Conclusions:Initial ultrasonic temperature,ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis.Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing,which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.

Rapid Ultrasonic-Assisted Soldering of AZ31B Mg Alloy/6061 Al Alloy with Low-Melting-Point Sn–xZn Solders Without Flux in Air

A novel ultrasonic-assisted low-temperature soldering was developed to join AZ31B Mg alloy and 6061 Al alloy with a series of Sn–x Zn solders. The average maximum shear strength of the joints reaches up to 87.5 MPa at soldering temperature of 300 °C under ultrasonic assistance for only 5 s using Sn–20 Zn solder. The fracture path propagates completely in the soldering seam. The results indicate that the microjet generated by ultrasonic pressure in liquid solder could strike and splinter the Mg_2Sn intermetallic compounds into small pieces, which contributes to the enhancement of the joint strength. In addition, the primary Al(Zn) solid solution phase formed during cooling stage could also strengthen the joint due to the prevention of microcracks propagation.

Determination of Lignans in Schisandra sphenanthera and Schisandra chinensis Using Ionic Liquid-based Ultrasonic-assisted Extraction and High-performance Liquid Chromatography

A green, rapid and precise sample pretreatment technique, IL-based UAE（ionic liquid-based ultrasonic- assisted extraction）, was coupled with high-performance liquid chromatographic separation to identify the main effective components in Schisandra sphenanthera（S, sphenanthera） and Schisandra chinensis（S, ehinensis） including schisantherin A, schisandrin A, and deoxyschizandrin. Four different types of ionic liquids have been investigated, finally [C6MIM][BF4] was used as the extraction solvent. A powder form of S. sphenanthera and S. chinensis was mixed with the [C6MIM][BF4] to produce a suspension. This suspension was ultrasonically extracted in a water bath at room temperature. Several of the process parameters were optimized, including the type of ionic liquid used and its volume, the sample amount, the size of the sample particle, the extraction time, etc. HPLC calibration curves were estab-lished for all the analytes and proved to be linear（r〉0.9999）. The lowest detection level for schisandrin A was 0.12μg/mL, for schisantherin A was 0.08 μg/mL, and for deoxyschizandfin was 0.10μg/mL. The recoveries of the target compounds were from 74.19% to 109.33%. The standard deviations for detection were generally no more than 6.31%. In contrast to conventional extraction methods, the IL-based UAE did not involve volatile organic volatile solvents, and the analysis time, required sample and solvent vohtrnes were also lower than those of the conventional techniques.

Design,Ultrasonic-assisted Synthesis and Evaluation In vitro Antimicrobial Activity of Bis-isoxazole Derivatives Bearing Chloro-pyridinyl Group

An ultrasonic-assisted synthesis of bis-isoxazole derivatives was developed.Eight 3-(6-chloropyridin-3-yl)-5-{[(3-arylisoxazol-5-yl)methoxy]methyl}isoxazoles were synthesized by 1,3-dipolar cycloaddition reaction between substituted isoxazolyl alkyne compounds and 6-chloro-N-hydroxynicotinimidoyl chloride.The structures of the synthesized compounds were confirmed by HRMS,FTIR,^(1)H and^(13)C NMR spectroscopy.Wherein,the antifungal and antibacterial activities of target compounds were tested.The synthesized compounds 6a and 6h exhibited better antifungal activity in comparison with the standard drug itraconazole.The minimum inhibitory concentrations(MICs)of both compound 6a and compound 6h were both 4µg/mL against Candida albicans ATCC 10231.

Sub-micron Co-Al_(2)O_(3) composite powders prepared by room-temperature ultrasonic-assisted electroless plating

Sub-micron Co-Al_(2)O_(3)composite powders were synthesized by ultrasonic-assisted electroless plating process at room temperature with a one-step activating method pretreatment.The effect of process parameters on plating rate,Co content,and the uniformity of cobalt layer was analyzed by transmission electron microscopy(TEM).The results show that as the initial pH values of plating bath increase,the plating rate increases.The plating rate declines as the load increases when the load of powders is less than 12 g·L^(-1),but increases when the load is greater than 12 g·L^(-1).The relative Co content of the Co-Al_(2)O_(3) powder declines with the powder load increasing.

Thrust force model for ultrasonic-assisted micro drilling of DD6 superalloy

As a typical refractory material,the DD6 nickelbased single-crystal superalloy has important applications in the aviation industry.Ultrasonic-assisted drilling is an advanced machining method that significantly improves machining of refractory materials.The drilling thrust force influences the hole surface quality,burr height,and bit wear.Therefore,it is necessary to predict the thrust force during ultrasonic-assisted drilling.However,there are few reports on the modeling of the thrust force in the ultrasonicassisted drilling of micro-holes.A thrust force prediction model for ultrasonic-assisted micro-drilling is proposed in this study.Based on the basic cutting principle,the dynamic cutting speed,dynamic cutting thickness,and acoustic softening effect caused by ultrasonic vibrations are factored into this model.Through model calibration,the specific friction force and specific normal force coefficients were determined.The model was verified through ultrasonic-assisted drilling experiments conducted at different feed rates,spindle speeds,frequencies,and amplitudes.The maximum and minimum errors of the average thrust force were 10.5%and 2.3%,respectively.This model accurately predicts the thrust force based on the parameters used for ultrasonic-assisted micro-hole drilling and can assist in the analysis and modeling of DD6 superalloy processing.

Ultrasonic-assisted Biodegradation of Endocrine DisruptingCompounds in Soil by Pseudomonas putida： the Importance of Rhamnolipid for Intermediate Product Degradation

The present study aimed to completely remove estrogens, including oestrone（E1）, oestradiol（E2）, oes-triol（E3）, 17a-ethinylestradiol（EE2） and bisphenol-A（BPA）, from soil using Pseudomonas putida（P., putida）. A centralcomposite design was developed to determine the optimal conditions of three variables（ultrasonication time, quantityof P. putida, and concentration of added rhamnolipid） for the removal of the estrogens, and the biodegradation ratesof the estrogens were investigated under the optimum conditions. Moreover, a quantitative structure-biedegradationrelationship（QSBR） was used to analyze the effect of the estrogenic physicochemical properties on the enhancementof the biological degradation. The optimal conditions were an ultrasonication time of 3 min, a P. putida quantity of 8mL, and a rhamnolipid concentration of 100 mg/L. These conditions resulted in removal of 100%, 94.86%, 94.90%,96.56% and 94.56% of El, E2, EE2, BPA and E3, respectively after 7 d. The degradations were more rapid and com-plete than those reported in previous studies, indicating the suitability of the adaptation of P. putida to estrogen de-gradation under conditions of ultrasonic-assistance and adding rhamnolipid, improvement was particularly apparentfrom the complete degradation of E3. Based on a Pearson correlation analysis, the estrogen molecule polar surfacearea（PSA） and surface tension were significantly related to the biodegradation effect. An analysis of the QSBR modelwith the estrogen biodegradation rates as a dependent variable and the PSA and surface tension as independent va-riables indicated that larger PSA caused decreased estrogen biodegradation, while the biodegradation progress wasdominated by the surface tension of the estrogens. The interaction of PSA and surface tension had an antagonistic ef-fect on the biodegradation of estrogens. Therefore, rhamnolipid/ultrasonication can significantly improve the biode-gradation rates of oestrogens in soil, while simultaneously adjusting other environmental conditions would influenceand control the biodegradation processes of estrogens.

Determination of Total Flavonoids in Acanthopanax senticosus(Rupr. et Maxim.) Harms by Enzymolysis and Its Technological Optimization

In order to optimize the ultrasonic extraction technique for the total flavonoid of leaf yellows plus, the contents of 21 leaf yellows plus total flavonoid from four regions in Heilongjiang Province were comparatively analyzed. The ultrasonic extraction technology was optimized by Box-Behnken response surface method, and the total flavonoid content of 21 kinds of Acanthopanax senticosus(Rupr. et Maxim.) Harms from different producing areas were analyzed by cluster analysis. The optimal process conditions were determined as ultrasonic time 30 min, solid-liquid ratio 1 : 12 and ultrasonic power 250 W, and the average yield of the total flavonoid was 1.453 mg·g^ (-1). By optimizing the ultrasonic-assisted extraction method, the total flavonoid content from different producing areas was compared in the experiment, which provided certain data support for the optimization of the extraction process in the future and laid a certain theoretical foundation for the quality analysis of Chinese medicinal materials.

Investigation of Two-Dimensional Ultrasonic Surface Burnishing Process on 7075-T6 Aluminum

A novel two-dimensional ultrasonic surface burnishing process(2D-USBP)is proposed.7075-T6 aluminum samples are processed by a custom-designed 2D-USBP setup.Parameter optimization of 2D-USBP is conducted to determine the best processing strategy of 7075-T6 aluminum.A uniform design method is utilized to optimize the 2D-USBP process.U〔3(133)and 4(72)tables are established to conduct parameter optimization.Burnishing depth,spindle speed,and feed rate are taken as the control parameters.The surface roughness and Vickers hardness are taken as the evaluation indicators.It establishes the active control models for surface quality.Dry wear tests are conducted to compare the wear-resistance of the 2D-USBP treated sample and the original sample.Results show that the machining quality of 2D-USBP is best under 0.24 mm burnishing depth,5000 r/min spindle speed,and 25 mm/min feed rate.The surface roughness of the sample is reduced from 2517.758 to 50.878 nm,and the hardness of the sample surface is improved from 167 to 252 HV.Under the lower load,the wear mechanism of the 2D-USBP treated sample is mainly abrasive wear accompanied by delamination wear,while the wear mechanism of the original sample is mainly delamination wear.Under the higher load,the accumulation of frictional heat on the sample surface transforms the wear mechanisms of the original and the 2D-USBP treated samples into thermal wear.

Isolation and purification of carbazole contained in anthracene slag by extraction combined with medium pressure liquid chromatography

Ultrasonic-assisted extraction(UAE)combined with medium pressure liquid chromatography(MPLC)was designed for carbazole separation from anthracene slag(AS).The effects of liquid/solid ratio,temperature,and extraction times on carbazole separation were investigated.When using CC14 and ethyl acetate as extraction solvents and combining with MPLC,carbazole recovery and purity are 75.1%and 95.4%,respectively.The mechanism for carbazole separation were presumed by examining intermolecular interactions such as N-H…π,π-π,and C-Cl…πinteractions.These results demonstrate that UAE/MPLC has a considerable potential as a green and promising strategy for separating and purifying carbazole and other chemicals from AS.

The Impact of Nickel Source/Doping Elements/Buffer on the Structure of Ni(OH)_2

The nano-nickel hydroxide samples were prepared by means of ultrasonic-assisted precipitation and the impact of source/doping element/buffer on the structure of Ni（OH）： was studied. The results of XRD, IR and TEM testing clearly revealed that larger anionic radius of the nickel sources or the buffer solution was conducive to the formation of α-Ni（OH）2. The proportion of α-Ni（OH）： samples doped with two elements was larger than that doped with single element. Additionally, speciation, valence as well as the radius of doping ions can directly affect the phase of Ni（OH）2.