Increase Of Ultrasonic Time Research Articles

Investigation in the interface adhesion strength between SU-8 photoresist and metal substrate by ultrasonic treatment

During the fabrication process of metal microstructures and microdevices by ultraviolet Lithographie Galvanoformung Abformung technology of SU-8, it is common for interface separation and bind failure due to the poor adhesion strength between SU-8 photoresist and metal substrate. In this paper, ultrasonic wave was introduced into the lithography process to improve the interface adhesion strength. Scratch test method was adopted to measure the interface adhesion strengths between SU-8 photoresist and metal substrate without ultrasonic treatment and with ultrasonic treatment under different ultrasonic conditions. The effects and corresponding mechanisms of ultrasonic time and ultrasonic power on the interface adhesion strength between SU-8 photoresist and metal substrate were investigated. The results showed that due to the input of the ultrasonic vibration, the crosslink network characteristics of SU-8 photoresist were changed. The internal stress in SU-8 photoresist was reduced and the interface adhesion strength was improved. The interface adhesion strength firstly increased and then decreased with the increase of ultrasonic time. The maximum interface adhesion work was 0.427 J/m2 at an optimized ultrasonic time of 10 min, which was higher than that of the sample without ultrasonic treatment by 39.5 %. Besides, in the experimental conditions, the interface adhesion strength first increased and then decreased with the increase of the ultrasonic power and the maximum interface adhesion strength attained at the ultrasonic power of 352 W. The ultrasonic treatment method can effectively improve the interface adhesion strength, so as to increase the product yield and performance.

Spectroscopic investigation on the sonodynamic damage to protein in the presence of eosine B

In this work, bovine serum albumin (BSA) and eosine B (EB) were selected as a model protein and sonosensitizer, respectively. The sonodynamic damage to protein in the presence of EB and its mechanism were studied by means of absorption and fluorescence spectra. The results indicated that the synergistic effects of ultrasound and EB can efficiently damage the BSA molecules, and the damage of protein could be mainly due to the generation of reactive oxygen species (ROS). The damage degree of protein increased with the increase of ultrasonic time and EB concentration because of the increased quantities of ROS. Hydroxyl free radical (OH) was the major mediators of the ultrasound-inducing proteins damage in the presence of EB. In addition, the quantities of ROS from the diphenylcarbazide (DPCI)–EB solutions and the DPCI–fluorescein (FS) solutions with or without ROS scavengers were contrasted, respectively. The results show that FS mainly produce OH, but the quantities of ROS in the presence of FS were lower than those of EB, which indicates that the nitro and bromine substituent groups on the benzene ring of FS increase the quantity of ROS, but do not change the kinds of ROS.

Effects of ultrasonic irradiation on colloidal stability of B4C and PbO particles and preparations of epoxy composites

The effects of the ultrasonic irradiation on the colloidal stability of B4C and PbO fillers suspended in low‐viscosity hardener and the subsequent preparations of the epoxy composites were studied. The ultrasonic dispersion ensured a long‐period colloidal stability of the filler particles with their initial particle size levels in liquid hardener. For less hard PbO microparticles, the particle size decreased with an increase in ultrasonication time by fragmentation. The effectiveness of ultrasonication was remarkable for the nanoparticles owing to the presence of greater surface area. FT‐IR measurements revealed that a particle‐to‐hardener interaction became stronger. Virtually, this interaction was critical to yield both the homogeneous distribution and strong interface of the B4C and PbO particles in the epoxy matrices, resulting in the improved mechanical and thermal performances of the B4C/epoxy and PbO/epoxy composites. POLYM. COMPOS., 37:1839–1847, 2016. © 2015 Society of Plastics Engineers

Effect of ultrasonic treatment on the degradation and inhibition cancer cell lines of polysaccharides from Porphyra yezoensis.

The exposure of polysaccharides solutions to high-energy ultrasound produces a permanent reduction in viscosity and change in activity. However, the exact mechanism which occurs in the process is still not clear. In this work, degradation of polysaccharides from Porphyra yezoensis (PP) was indirectly and directly judged by intrinsic viscosity and high performance gel permeation chromatography. The degradation process was established with dynamics and affirmed by theoretical derivation. Inhibition of cancer cell lines (SGC-7901, 95D) was also investigated by assays of tetrazolium colorimetric. The intrinsic viscosity of the degraded PP decreased exponentially with increase in ultrasonic time, and theoretical derivation was established and confirmed well. The distribution and new fraction of degraded polysaccharides was found. Ultrasound degraded preferentially large PP molecules and cleavage took place roughly at the centre of the molecules. During ultrasound degradation the molecular weight distribution was narrowed. The inhibition activities of SGC7901 with ultrasound degraded polysaccharides were increased.

Ionic liquid-assisted sonochemical synthesis of SnS nanostructures

SnS nanoparticles have been successfully synthesized by the ionic liquid-assisted sonochemical method (ILASM). The starting reagents were anhydrous SnCl2, thioacetamide, dissolved in ethanol and ionic liquid (IL)1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) mixtures. Our experiments showed that IL plays an important role in the morphology of SnS. A 1:1 ethanol:IL mixture was found to yield the more interesting features. The lower concentration of Sn (II) in solution favored the presence of nanoplatelets. An increase in ultrasonic time favored crystalline degree and size as well. Also, the effect of additives as 3-mercaptopropionic acid, diethanolamine, ethylene glycol, and trioctyl phosphine oxide is reported. X-ray diffraction (XRD) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis-DRS) were used to characterize the obtained products.

Effects of High Power Ultrasonic Pretreatment on Physicochemical Quality and Enzymatic Activities of Dried Longan

The physicochemical quality and inactivation of polyphenol oxidase (PPO), peroxidase (POD) in dried longan with high power ultrasonic pretreatment was investigated. Effect of high power ultrasonication was compared with a traditional chemical pretreatment with potassium metabisulfite and non-pretreatment. Chemical qualities, such as aw, MC, TSS, and TA of the ultrasonic pretreated dried longan samples were significantly lower than those of the control samples (P£0.05), whereas their pH were higher than those of the control samples. Increase in ultrasonication time resulted in decreases of aw, MC, TSS, and TA, but an increase of pH. The firmness, lightness (L*), and yellowness (b*) values increased and redness (a*) values decreased when the sample was pretreated with increasing ultrasonication time. The application of high power ultrasonic pretreatment for 10, 20, and 30 min could reduce PPO activity by 49.99%, 57.18%, and 70.68%, and POD activity by 47.63%, 86.16%, and 94.06%, respectively. The PPO and POD activities were significantly decreased with increasing ultrasonication time. Panelists were most satisfied with sensory properties of the dried longan with 30 min of high power ultrasonic pretreatment.

Sonochemical synthesis and ppb H2S sensing performances of CuO nanobelts

Abstract CuO nanobelts were successfully prepared by a wet-chemical method assisted by ultrasonic irradiation. The structure characterizations for samples obtained under different ultrasonic time clearly demonstrated that Cu(OH) 2 nanorods were firstly formed, and then transformed into one-dimensional (1D) Cu(OH) 2 /CuO core–shell nanostructures, and into CuO nanobelts with an increase of ultrasonic time through an interesting epitaxial growth process. The length and width of the nanobelts were 0.5–1.2 μm and 60 nm, respectively. The sensor response of the nanobelts was about 1.2–100 ppb H 2 S gas at a working temperature of 135 °C. Moreover, the CuO nanobelts had almost not response to 10 ppm H 2 , NH 3 , CO and CH 4 at 135 °C. Thus, the CuO nanobelts are very promising for fabrication of H 2 S gas sensor.

Effect of Ag nanoparticle addition and ultrasonic treatment on a stable TiO2 nanofluid

Nanoparticles, when homogeneously dispersed in a base fluid, e.g. water, ethylene glycol etc. are commonly known as nanofluids. Nanofluids have gained attention in the scientific community for their enhanced thermal properties. One of the major problems in using nanofluids as a heat transfer medium for commercial applications is that, in most of the closed circuit industrial cooling processes, the cooling fluid has to be replaced after several cycles of cooling operation because of an increased presence of contaminants. If nanofluids were used as a coolant, it would be very hard to separate the nanoparticles from the waste fluid. The present work is aimed at the separation and recycling of nanoparticles from fluid waste by means of quick settling of titanium dioxide nanoparticles using silver nanoparticles along with ultrasonic treatment. It is observed that with increasing silver concentration and time of ultrasonication, the stability of the dispersion decreases. There is a value for both the silver concentration and ultrasonication time above which the settling time decreases drastically.

Effects of Ultrasonic Dispersion on the Separation of Single-Walled Carbon Nanotubes

Recently, gel chromatography has been demonstrated as an effective method for the separation of single-walled carbon nanotubes (SWCNTs) according to their electronic type and structure. The separation of SWCNTs was thought to result from the different affinity forces between the gel and various SWCNTs. Based on this method, we investigated the effect of ultrasonic time on the dispersion and separation of metallic and semiconducting SWCNTs. At a low ultrasonic power, with the increase of ultrasonic time, better monodispersed SWCNTs in sodium dodecylsulfate (SDS) aqueous solution were obtained. The UV-visible-near infrared (UV-Vis-NIR) absorption, Raman and photoluminescence (PL) spectroscopic characterizations confirmed that under the condition of ultrasonication (2 h), higher-purity metallic tubes and semiconducting tubes with different diameter distributions could be obtained. We believe that the control of the ultrasonication time may tune the mono-dispersity and the length of SWCNTs, which would further influence the difference in affinity forces between various SWCNTs and the gel, therefore leading to different separation results.

Improved electroluminescence performance of ZnS:Cu,Cl phosphors by ultrasonic treatment

ZnS:Cu,Cl electroluminescence (EL) phosphors were prepared by high-temperature (1150 °C) solid-state reaction, subsequent ultrasonic treatment ( t=0–60 min) and final low-temperature annealing process at 750 °C. The as-synthesized phosphors were characterized by X-ray powder diffraction (XRD), UV–vis absorbance spectra, electron probe microanalyzer (EPMA) and photoluminescence (PL) spectra. EL performance was investigated on an EL lamp fabricated by screen-printing at 100 V and 400 Hz. Ultrasound irradiation leads to intensity reductions and width increases of some XRD diffraction peaks, and results in a slight red-shift of UV–vis absorption edge. It also exhibits strong influences on PL and EL properties of the phosphors. Generally, PL performance monotonically declines with the increase of ultrasonic time, while EL performance benefits from the ultrasonic treatment and is superior to that of the commercial ones. The defects in the microstructure induced by the ultrasonic treatment are the fundamental reason for the change of PL and EL performances.

The Effect of Ultrasonic Vibration on the Compaction Characteristics of Ibuprofen

ABSTRACTAn ultrasonic (US) compaction rig has been developed, capable of providing compaction pressure together with high-power ultrasonic vibrations of 20 kHz to a powder or granular material in a die. The rig has been used to investigate the effect of ultrasound on the compaction properties of ibuprofen, a drug with poor compaction properties which produces tablets that are weak and frequently exhibit capping. It was found that coherent ibuprofen tablets could be prepared by ultrasound-assisted compaction at pressures as low as 20–30 MPa. Application of ultrasound before and after compaction was found not to be as effective as ultrasound applied during compaction. The breaking forces of the tablets produced with ultrasound applied during compaction were found to be consistently significantly higher than when compaction was performed conventionally, or with ultrasound applied before or after compaction. Application of ultrasound during compaction made it possible to increase tablet mechanical strength, typically by a factor of 2–5. It was concluded that pressure should be applied together with ultrasound in order to achieve a better acoustical contact, which is required to transmit vibrations from the horn to the material, and also to bond the surfaces of the particles.Ultrasound application during ibuprofen compaction also resulted in an increase in the apparent density, in relation to the apparent density of conventionally prepared tablets, of up to 14.4%. Ultrasound appears to improve particle rearrangement and provides energy for partial melting of particle asperities and subsequent fusion of particle surfaces, so as to increase interparticulate bonding. Solid bridge formation was thought to result in a reduction of void space, which in turn reduced the rate of water penetration into the compacts and consequently increased disintegration and dissolution times.It was found that the results of ultrasound-assisted compaction are influenced by formulation and US time. When ibuprofen was mixed with a second material, such as dibasic calcium phosphate dihydrate (DCP) or microcrystalline cellulose (MCC), stronger tablets were prepared by ultrasound-assisted compaction compared to the compacts containing no filler. Positive interactions were considered to have occurred due to ultrasound-induced bonding between the two materials. With an increase in DCP and MCC concentration in ibuprofen formulations, disintegration and drug dissolution rates of the tablets produced with ultrasound significantly increased.Using temperature-sensitive labels it was found that thermal changes occurred in powdered solids undergoing ultrasound-assisted compaction. Increases in the temperature of tablets were related to US amplitude and US time. With an increase in US amplitude from 5 to 13 µm, the temperature of the DCP tablet surface increased from 40 to 99°C. With an increase in US time from 1 to 5 sec, the temperature of the surface of ibuprofen tablets increased from 43 to 60°C. Increased tablet temperature was thought to be due to ultrasonic energy dissipation turned into heat.X-ray powder diffraction (XRD) studies of ibuprofen tablets prepared by ultrasound-assisted compaction at 32 MPa revealed that no changes in chemical or/and crystalline structure of the material occurred when ultrasound was applied for up to 5 sec (US amplitude 7 µm). An XRD study of DCP tablets produced by ultrasound-assisted compaction at 32 MPa with ultrasound of different amplitudes (5, 7, 13 µm) applied for 2 sec indicated that no material deterioration occurred in all the tested samples.