Ultrasound-assisted extraction of collagen from broiler chicken trachea and its biochemical characterization

Broiler chicken tracheas are a co-product from chicken slaughterhouses which are normally turned into low value animal feed despite their high levels of collagen. Typical collagen extraction by acid and/or pepsin usually results in relatively low yield. Ultrasound-assisted extraction (UAE) could be a means to improve collagen yield. The objectives of this study were to investigate the effects of ultrasonic parameters on the yield and biochemical properties of trachea collagen (TC). Conventional extraction using acetic acid and pepsin for 48 h resulted in acid-soluble (AS) and pepsin-soluble (PS) collagen with a yield of 0.65% and 3.10%, respectively. When an ultrasound with an intensity of 17.46 W·cm⁻² was applied for 20 min, followed by acid extraction for 42 h (U-AS), the collagen yield increased to 1.58%. A yield of 6.28% was obtained when the ultrasound treatment was followed by pepsin for 36 h (U-PS). PS and U-PS contained collagen of 82.84% and 85.70%, respectively. Scanning electron microscopy images revealed that the ultrasound did not affect the collagen microstructure. All collagen samples showed an obvious triple helix structure as measured by circular dichroism spectroscopy. Fourier transform infrared spectroscopy indicated that the ultrasound did not disturb the secondary structure of the protein in which approximately 30% of the α-helix content was a major structure for all collagen samples. Micro-differential scanning calorimetry demonstrated that the denaturation temperature of collagen in the presence of deionized water was higher than collagen solubilized in 0.5 M acetic acid, regardless of the extraction method. All collagen comprised of α₁ and α₂-units with molecular weights of approximately 135 and 116 kDa, respectively, corresponding to the type I characteristic. PS and U-PS collagen possessed higher imino acids than their AS and U-AS counterparts. Based on LC-MS/MS peptide mapping, PS and U-PS collagen showed a high similarity to type I collagen. These results suggest that chicken tracheas are an alternative source of type I collagen. UAE is a promising technique that could increase collagen yield without damaging its structure.     

Effects of preliminary treatment by ultrasonic and convective air drying on the properties and oil absorption of potato chips

The initial water content was closely related to the oil absorption and properties of fried food. The effects of convective air drying (D) and ultrasound combined convective air drying (UD) pretreatment on the properties and oil absorption of potato chips have been investigated. The oil contents were 48.48 ± 1.42% and 39.78 ± 3.08% for control samples (without D and UD pretreatment) and ultrasound treated samples (without D pretreatment). When the mass loss of samples was reached the proportion of quality to without drying samples quality 80%, 50%, and 20%, the oil contents of D pretreated samples decreased by 12.67%, 28.24% and 62.07%, respectively, and the oil contents of UD pretreated samples decreased by 7.42%, 24.10% and 51.76% (compared to the ultrasound pretreated samples ), respectively. By applying ultrasound before frying, more cracks and pores were exhibited of fried potato chips. After drying process, potato chips exhibited less disruption of cell structure and less deformation of cell irregular. The hardness of the D and UD pretreated potato chips increased with the extension of drying. The FTIR analysis stated the formation of amylose-lipid complexes. This research could contribute to providing evidence for the development and application of the pretreatment strategies.     

Direct contact ultrasound for fouling control and flux enhancement in air-gap membrane distillation

Air Gap Membrane distillation (AGMD) is a thermally driven separation process capable of treating challenging water types, but its low productivity is a major drawback. Membrane fouling is a common problem in many membrane treatment systems, which exacerbates AGMD’s low overall productivity. In this study, we investigated the direct application of low-power ultrasound (8–23 W), as an in-line cleaning and performance boosting technique for AGMD. Two different highly saline feedwaters, namely natural groundwater (3970 μS/cm) and RO reject stream water (12760 μS/cm) were treated using Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes. Theoretical calculations and experimental investigations are presented, showing that the applied ultrasonic power range only produced acoustic streaming effects that enhanced cleaning and mass transfer. Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that ultrasound was capable of effectively removing silica and calcium scaling. Ultrasound application on a fouled membrane resulted in a 100% increase in the permeate flux. Cleaning effects accounted for around 30–50% of this increase and the remainder was attributed to mass transfer improvements. Contaminant rejection percentages were consistently high for all treatments (>99%), indicating that ultrasound did not deteriorate the membrane structure. Scanning Electron Microscopy (SEM) analysis of the membrane surface was used to confirm this observation. The images of the membrane surface demonstrated that ultrasound successfully cleaned the previously fouled membrane, with no signs of structural damage. The results of this study highlight the efficient and effective application of direct low power ultrasound for improving AGMD performance.     

Calcium permeation property and firmness change of cherry tomatoes under ultrasound combined with calcium lactate treatment

This study aimed to investigate the effect of ultrasound combined with calcium lactate (2%, w/v) treatment (U + Ca) on calcium permeation and firmness of cherry tomatoes. Calcium distribution and fruit pectin nanostructure were also analysed by transmission electron microscope (TEM) and atomic force microscopy (AFM), respectively. The firmness (31.45 N) was maintained when ultrasound energy density was 20 W/L for 15 min at 15 °C. The Ca content increased in U + Ca treated fruit. Meanwhile, the Peleg’s model could be used to express the change of solid gain in cherry tomatoes under ultrasound treatment at 15, 20, and 25 °C. According to the AFM results, the width (≥40 nm) and length (≥2 μm) of chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) chains with large frequency was observed in U + Ca treated fruit. Under desirable conditions (15 °C, 15 min, 20 W/L), ultrasound combined with calcium lactate could maintain the quality of cherry tomatoes.     

The influence of porosity on ultrasound attenuation in carbon fiber reinforced plastic composites using the laser-ultrasound spectroscopy

Wideband acoustic spectroscopy with a laser ultrasound source for quantitative analysis of the effect of porosity on the attenuation coefficient of longitudinal acoustic waves in carbon fiber reinforced plastic (CFRP) composite materials was experimentally implemented. The samples under study had different bulk-porosity levels (up to 10%), which were determined using X-ray computer tomography. A resonance ultrasound attenuation peak associated with the one-dimensional periodicity of the layered composite structure was observed for all samples. The absolute value of the resonance-peak maximum and its width depend on the local concentration of microscopic isolated pores and extended delaminations in the sample structure. The obtained empirical relationships between these parameters of the frequency dependence of the ultrasound attenuation coefficient and the type of inhomogeneities and their volume concentration can be used for rapid evaluation of the structural quality of CFRP composites.     

Transport properties of aqueous solutions of calcium lactate in the absence and presence of β-cyclodextrin

Mutual diffusion coefficients and electrical conductivity of a well-known food additive and supplement, or excipient in pharmaceutical formulations, calcium lactate, have been measured in the absence and presence of β-cyclodextrin in aqueous solutions, at 298.15 K. The dependence of conductivity on concentration has been analysed using the Fuoss-Edelson method. The values of the Nernst diffusion coefficients, for binary solutions, derived from conductance and from diffusion experiments are in good agreement. The presence of β-cyclodextrin leads to a non-expected effect on the transport properties of the aqueous solutions of calcium lactate. These data have been justified with help of ¹H NMR spectroscopy. The effect on the water structure, reducing the hydration shell of lactate, is argued. This leads to an increase of the effective concentration of calcium lactate in solution contributing to an increase in the diffusion coefficients and a decrease in the dependence of the electrical conductance on the concentration.     

Ultrasound-mediated transdermal drug delivery of fluorescent nanoparticles and hyaluronic acid into porcine skin in vitro

Transdermal drug delivery(TDD) can effectively bypass the first-pass effect. In this paper, ultrasound-facilitated TDD on fresh porcine skin was studied under various acoustic parameters, including frequency, amplitude, and exposure time. The delivery of yellow–green fluorescent nanoparticles and high molecular weight hyaluronic acid(HA) in the skin samples was observed by laser confocal microscopy and ultraviolet spectrometry, respectively. The results showed that,with the application of ultrasound exposures, the permeability of the skin to these markers(e.g., their penetration depth and concentration) could be raised above its passive diffusion permeability. Moreover, ultrasound-facilitated TDD was also tested with/without the presence of ultrasound contrast agents(UCAs). When the ultrasound was applied without UCAs,low ultrasound frequency will give a better drug delivery effect than high frequency, but the penetration depth was less likely to exceed 200 μm. However, with the help of the ultrasound-induced microbubble cavitation effect, both the penetration depth and concentration in the skin were significantly enhanced even more. The best ultrasound-facilitated TDD could be achieved with a drug penetration depth of over 600 μm, and the penetration concentrations of fluorescent nanoparticles and HA increased up to about 4–5 folds. In order to get better understanding of ultrasound-facilitated TDD, scanning electron microscopy was used to examine the surface morphology of skin samples, which showed that the skin structure changed greatly under the treatment of ultrasound and UCA. The present work suggests that, for TDD applications(e.g., nanoparticle drug carriers, transdermal patches and cosmetics), protocols and methods presented in this paper are potentially useful.     

Effects of ultrasound on polymeric foam porosity

A variety of materials require functionally graded cellular microstructures whose porosity is engineered to meet specific applications (e.g. mimic bone structure for orthopaedic applications; fulfil mechanical, thermal or acoustic constraints in structural foamed components, etc.). Although a huge variety of foams can be manufactured with homogenous porosity, there are no generic processes for controlling the distribution of porosity within the resulting matrix. Motivated by the desire to create a flexible process for engineering heterogeneous foams, the authors have investigated how ultrasound, applied during the formation of a polyurethane foam, affects its cellular structure. The experimental results demonstrated how the parameters of ultrasound exposure (i.e. frequency and applied power) influenced the volume and distribution of pores within the final polyurethane matrix: the data demonstrates that porosity (i.e. volume fraction) varies in direct proportion to both the acoustic pressure and frequency of the ultrasound signal. The effects of ultrasound on porosity demonstrated by this work offer the prospect of a manufacturing process that can adjust the cellular geometry of foam and hence ensure that the resulting characteristics match the functional requirements.     

Spatial characterization of the response of a silica optical fiber to wideband ultrasound

Optical fibers have long been recognized as a promising technology for remote sensing of ultrasound. Nonetheless, very little is known about the characteristics of their spatial response, which is significantly affected by the strong acoustic mismatches between the fiber and surrounding medium. In this Letter, a new method is demonstrated for wideband spatial acoustic characterization of optical fibers. The method is based on the excitation of a point-like acoustic source via the opto-acoustic effect, while a miniature fiber sensor is implemented by a π-phase-shifted fiber Bragg grating. Despite the relative complexity of acoustic wave propagation in the fiber, its spatial sensitivity in the high frequency band (6-30?MHz) exhibited an orderly pattern, which can be described by a simple model. This property reveals new possibilities for high-performance imaging using fiber-based ultrasound sensors, where knowledge of the sensor's spatial sensitivity map is generally required.     

Airborne ultrasound for the precipitation of smokes and powders and the destruction of foams

Sonochemistry is generally associated with the use of power ultrasound in liquid media. Under such circumstances acoustic cavitation can drive a range of reactions and processes. The use of airborne ultrasound in processing is less familiar because of the difficulties that relate to the use of ultrasound in gaseous systems. Firstly there is a greater attenuation (power loss) in the transmission of sound through air compared with that through liquid. Secondly the transfer of acoustic energy generated in air into a liquid or solid material is inefficient due to the mismatch between acoustic impedances of gases and solids or liquids. Despite this, applications do exist for airborne ultrasound but the source must be very powerful and efficient. In this way one can obtain levels of intensities at which it is possible to use ultrasound for specific applications such as to agglomerate fine dusts and to break down foams.     

Synergistic effect of hydrogen peroxide production and sonochemiluminescence under dual frequency ultrasound irradiation

The synergistic effect of H(2)O(2) production and sonochemiluminescence (SCL) was studied under both orthogonal and opposite dual irradiation at the frequencies of 28, 584 and 970 kHz and at various acoustic powers. The largest reduction in H(2)O(2) production was observed under opposite dual irradiation at a 28/28 kHz frequency without considering the acoustic power levels. The largest enhancement was observed under dual irradiation at a frequency of 28/970 kHz. This enhancement might be due to the increased number of bubbles that underwent violent collapse by low frequency ultrasound (28 kHz). These results were also confirmed by observing the SCL. Under dual irradiation at relatively high frequencies (i.e., 584 and 970 kHz), the synergistic effect was high at low acoustic power levels. However, the effect tended to decrease (to the equivalent of the calculation from the result of each single irradiation) with increasing acoustic power. Unlike dual irradiation coupled with a frequency of 28 kHz, the inhibition effect was not observed under dual irradiation at relatively high frequencies. With respect to H(2)O(2) production, the production rate constants of H(2)O(2) followed the order of 584/584>584/970>28/970≈28/584>28/28 kHz, which resulted from the fact that the production efficiency of H(2)O(2) at an irradiation frequency of 584 kHz was considerably higher than that at other frequencies.     

Intensified dissolution of uranium from graphite substrate using ultrasound

Decontamination of graphite structural elements and recovery of uranium is crucial for waste minimization and recycle of nuclear fuel elements. Feasibility of intensified dissolution of uranium-impregnated graphite substrate using ultrasound has been studied with objective of establishing the effect of operating parameters and the kinetics of sonocatalytic dissolution of uranium in nitric acid. The effect of operating frequency and acoustic intensity as well as the acid concentration and temperature on the dissolution of metal has been elucidated. It was observed that at lower acid concentrations (6 M–8 M), the dissolution ratio increases by 15% on increasing the bath temperature from 45 to 70 °C. At higher acid concentration (>10 M), the increase was only around 5–7% for a similar change in temperature. With 12 M HNO₃, pitting was also observed on the graphite surface along with erosion due to high local reaction rates in the presence of ultrasound. For higher frequency of applied ultrasound, lower dissolution rate of uranium was observed though it also leads to high rates of erosion of the substrate. It was thus established that suitable optimization of frequency is required based on the nature of the substrate and the choice of recycling it. The dissolution rate was also demonstrated to increase with acoustic intensity till it reaches to the maximum at the observed optimum (1.2 W/cm² at 33 kHz). Comparison with silent conditions revealed that enhanced rate was obtained due to the use of ultrasound under optimum conditions. The work has demonstrated the effective application of ultrasound for intensifying the extent of dissolution of metal.     

超声激发声信号幅值实时监测HIFU焦域组织损伤*

聚焦超声消融肿瘤过程中的损伤实时监测是临床治疗面临的一个关键难题,双频聚焦超声不仅能提高治疗效率,且能在共焦区域激发出声信号,该声信号的幅值、频率等信息与焦域组织的机械和声学特性紧密相关。本文构建了一种双频聚焦超声治疗及组织损伤实时监测系统。该系统在聚焦超声辐照离体组织过程中,通过外部水听器接收双频激发的组织声发射信号,并通过上位机进行高速数据采集、数字滤波、时频处理等,分析声发射信号幅值与离体组织损伤之间的变化规律。实验研究结果表明：随着焦域组织损伤的形成,其弹性等声学特征发生改变,导致声发射信号幅值逐渐降低,表明声发射信号幅值的变化可较好地反映靶组织声学特征和结构的变化,从而实现聚焦超声治疗中靶组织损伤的实时监测。本文提出的监测方案相比传统超声影像监控更灵敏,有望为聚焦超声临床治疗中的组织损伤监控提供一种新的实时监测方案和手段。     

Perceptual weighting of individual and concurrent cues for sentence intelligibility: frequency, envelope, and fine structure

The speech signal may be divided into frequency bands, each containing temporal properties of the envelope and fine structure. For maximal speech understanding, listeners must allocate their perceptual resources to the most informative acoustic properties. Understanding this perceptual weighting is essential for the design of assistive listening devices that need to preserve these important speech cues. This study measured the perceptual weighting of young normal-hearing listeners for the envelope and fine structure in each of three frequency bands for sentence materials. Perceptual weights were obtained under two listening contexts: (1) when each acoustic property was presented individually and (2) when multiple acoustic properties were available concurrently. The processing method was designed to vary the availability of each acoustic property independently by adding noise at different levels. Perceptual weights were determined by correlating a listener's performance with the availability of each acoustic property on a trial-by-trial basis. Results demonstrated that weights were (1) equal when acoustic properties were presented individually and (2) biased toward envelope and mid-frequency information when multiple properties were available. Results suggest a complex interaction between the available acoustic properties and the listening context in determining how best to allocate perceptual resources when listening to speech in noise.     

Effects of ultrasound treatment on the starch properties and oil absorption of potato chips

As a non-thermal processing method, the ultrasound treatment prior to the frying process has been demonstrated with great potential in reducing the oil absorption of fried food. This research aimed to evaluate the effect of ultrasound pretreatment on starch properties, water status, pore characteristics, and the oil absorption of potato slices. Ultrasound probe set with two power (360 W and 600 W) at the frequency of 20 kHz for 60 min was applied to perform the pretreatments. The results showed that ultrasound pretreatment led to the surface erosion of starch granules and higher power made the structure of starch disorganized. Moreover, the fraction of bound water and immobilized water were changed after ultrasonic pretreatment. Pores with the minor diameters (0.4–3 μm and 7–12 μm) were formed after ultrasound pretreatment. The penetrated surface oil (PSO) content, and structure oil (STO) content were reduced by 27.31% and 22.25% respectively with lower power ultrasound pretreatment. As the ultrasound power increased, the surface oil (SO) content and PSO content increased by 25.34% and 12.89% respectively, while STO content decreased by 38.05%. By using ultrasonic prior to frying, the quality of potato chips has been greatly improved.     

Ultrasonic propagation properties of articular cartilage at 100 MHz

A pilot study on articular cartilage assessed the contributions of individual matrix components to ultrasound propagation. The influence of collagen fibril orientation and collagen cross linking was also assessed. Sections of adult bovine articular cartilage cut both parallel and perpendicular to the articular surface were examined using the scanning laser acoustic microscope (SLAM) operating at an ultrasonic frequency of 100 MHz. A set of samples was evaluated that had been sequentially treated by enzymes to (1) remove 85% of the chondroitin sulfate; (2) remove remaining glycosaminoglycans, glycoproteins, and other noncollagen proteins, leaving only the collagen fibril network; and (3) disrupt the collagen intermolecular cross links. Two striking observations were made: a profound effect of the "preferred" collagen fibril orientation on ultrasonic speed and a marked increase in attenuation coefficient when intermolecular cross links were broken in the collagen.     

New acoustooptic effect: Constant high diffraction efficiency in wide range of acoustic power

A new effect, viz., acoustooptic Bragg diffraction without the overmodulation mode, in which the efficiency of the Bragg order attains its maximal value (close to 100%) upon an increase in the intensity of an acoustic wave and then remains practically unchanged, is predicted theoretically and observed experimentally. The effect takes place in the case of considerable bending of phase fronts of the acoustic field in the acoustooptic diffraction plane and attains its maximal value at a relatively low frequency of sound, a small width of a piezoelectric transducer, strong acoustic anisotropy of the medium, and a large distance between the light beam and the piezoelectric transducer.     

Low frequency acoustic signals associated with rock falls,thunderstorms, and wind turbulences in field environment

This paper characterized the observed low frequency acoustic signals generated by rock falls, thunderstorm, and wind turbulence in large rocky landslide. A digital infrasonic recording system was deployed on site to capture real-time low frequency acoustic signals associated with rock falls. An advanced non-stationary signal analysis method, i.e. Empirical Mode Decomposition (EMD), was applied to get insight to the characteristics of the low frequency acoustic signals induced by the hazards. Joint time–frequency distribution spectra technique was used to detect distinctive features of the events. The study shows that the low frequency acoustic signals can be excited by rock falls, thunderstorm and wind turbulence in the field environment, but the signal varies in both time domain and frequency domain with different patterns depending on the physical processes. The results demonstrated that the EMD-based signal processing technique is capable of extracting distinctive features to differentiate acoustic signals in real environment.     

Ultrasonic irradiation in the enzymatic extraction of collagen

The application of ultrasonic irradiation (40 KHz, 120 W) in the enzymatic extraction of bovine tendon collagen has been investigated. Our results show that using the ultrasonic irradiation increases the yield of collagen up to ～124% and significantly shortens the extraction time in comparison with the conventional pepsin isolation method. Such improvements are attributed to the enhancement of the enzyme activity and the dissolution of collagen substrate because the ultrasonic irradiation disperses the pepsin aggregates and opens up the collagen fibrils, thus the enzymatic hydrolysis is facilitated. AFM imaging shows the same fibrillar structure of tendon collagens generated from both the methods. The CD and FT-IR measurements reveal that the triple helix structure of collagen remains intact even after the ultrasonic irradiation. This study shows that the mild ultrasound irradiation can effectively improve the efficiency of pepsin extraction of natural collagen without any compromise of the resultant collagen quality.