Textile industry wastewater has large amounts of organic dyes which

Textile industry wastewater has large amounts of organic dyes, which are resistant to the biological methods. Moreover, other physical and chemical processes like adsorption and coagulation merely transfer contaminants to a secondary phase requires more treatment [4]. Hence, it is significant to find effective wastewater remediation methods like AOPs, which can not only degrade but also mineralize different contaminants without producing secondary waste [5]. Among AOPs, the Fenton and sonication processes are simple and efficient methods which are applied for the mineralization of various contaminants from polluted water sources [3]. Hydroxyl radicals (OH) as the most powerful oxidizing agent in AOPs, can be generated by the Fenton reaction involving ferrous iron (Eq. (1)) or from water dissociation under ultrasonic irradiation (Eq. (2)) through cavitation phenomenon [6]. After directing ultrasonic waves into a liquid, the cavitation leads to formation, growth, and finally collapse of microbubbles producing high localized temperatures and pressures (hot spot approach) [7]. However, ultrasonic process consumes more time and gli protein compared to other methods due to the low degradation rate; hence it can be combined with other processes like Fenton process to enhance their efficiency for the wastewater treatment [8].
On the other hand, homogeneous Fenton process can be just performed in acidic condition (pH 3) preventing the iron precipitation; it also needs to risky storage and transportation of hydrogen peroxide (H2O2). Moreover, recycling of homogeneous catalyst as well as its separation from the treated wastewater confines the application of Fenton process. Application of heterogeneous Fenton process with no need for catalyst separation and low leached iron is the practical solution to overcome these obstacles [2]. Heterogeneous Fenton catalysts including pyrite [9], magnetite [10], and goethite [11] are used in this process in which superficial solid Fe ions catalyze the production of OH. The pyrite (FeS2) is the most abundant metal sulfide in nature and nontoxic. It has potential for utilization in the heterogeneous Fenton reaction. The usage of synthesized pyrite has been studied in several wastewater treatment procedures, such as the Fenton and adsorption processes [12,13]. It should be mentioned that the heterogeneous Fenton process has some limitations compared to the homogeneous one including high mass transfer resistance and few active reaction sites. The effective methods to solve these drawbacks are applying nanostructured particles and ultrasonic irradiation [14].
Plasma is ionized gas, which composes of negative and positive ions, electrons and neutral species, which is noticed as the forth state of matter, which is an environmentally-friendly method to produce various nanostructures for various applications [15]. For instance, non-thermal plasma techniques such as glow discharge, radio frequency, and silent discharge have been used for modification of different catalysts surfaces and enhancement of their efficiencies [16,17]. For example, the plasma treatment alters the activity and surface structure of natural clinoptilolite and synthesized zeolites [16]. The catalytic activity and stability of the Pd/HZSM-5 catalyst improve after plasma treatment [18]. The selectivity for hydrogenation of acetylene increases after using the H2, Ar and O2 atmosphere plasma for modified Pd/TiO2 catalyst [19]. Glow discharge plasma treated magnetite using oxygen and argon was applied for treatment of an oxazine dye by catalytic ozonation [20].

Experimental procedure

Results and discussion

Conclusions
In this study, environmentally friendly argon plasma method was utilized successfully to produce modified pyrite, which characterized by XRD, FT-IR, BET and SEM methods. The sputtering effect of Ar glow discharge plasma results in production of the PTP nanostructures with more surface area and hence extra active sites. Furthermore, the Ar plasma can remove some of impurities from the NP surface. Consequently, The PTP performance in heterogeneous sono-Fenton-like process was improved considerably in comparison of the NP for the treatment of RR84 as a model azo dye from textile industry. The optimized operational conditions for the dye degradation were found to be PTP of 4g/L, initial dye concentration of 10mg/L, pH 5, and ultrasonic power of 300W after 120min of process time. The enhancers increase and hydroxyl radical scavengers decline the dye degradation efficiency confirming the main role of OH radicals in the degradation of the RR84 during the US/PTP process. Then, GC–Mass was used for identification of some degradation intermediates. The other significant advantages of the stable PTP are no need for adding of H2O2, low leached iron amount and application at the milder pH.

The conclusion of the theoretical part is that the relative

The conclusion of the theoretical part is that the relative theoretical data of the calculated implosion pressures were satisfactorily correlated with the relative intensities values of Ir,ave and Ir,max experimentally measured. Moreover the calculated curves suggest a possible operating zone between 50 and 60°C.
In the experimental part, US-assisted wool dyeing tests were carried out in the same plant used for mapping tests, in the same temperature range (40–70°C) and compared with the conventional wool dyeing test made at the “standard” temperature (98°C). The dyeing performances in presence and absence of US were verified by measuring ΔE (colour variation), Re,% (reflectance percentage), K/S (colour strength) and colour fastness.
From the data concerning the dyeing performances, it can be concluded that a temperature close to 60°C should be chosen as the recommended condition for US-assisted wool fabric dyeing. It must also be observed that the good result at 60°C is obtained also with a reduced dyeing time with respect to the reference test at 98°C. This leads to a reduction of the global energy consumption of the process.
Moreover the results obtained from mechanical tests on dyed samples demonstrate that the fabrics properties are better for the US-dyed sample, proving that the long dwell time at 98°C of the conventional dyeing negatively affects the wool fibres.

Introduction
A single bubble driven by a large sound field in a levitation cell undergoes nonlinear periodic radial oscillations, exhibiting at each apigenin a large expansion phase followed by a collapse. The high energy density at collapse time produces short visible light-pulse, termed single-bubble sonoluminescence (SBSL) [1–3]. When air is used as the dissolved gas, above a threshold in the driving amplitude, the energy focusing during the collapse produces temperatures high enough for air dissociation to take place, so that only argon and water vapor remain inside the bubble [4–10].
The bubble levitation cell is a now classical experimental setup used to observe this phenomenon. It is made of an acoustical resonator, spherical [11,12], cylindrical [1,13–15] or cubic [1,16,17], driven by piezoelectric ceramics in its breathing mode at a few tenth of kHz. The bubble is trapped at the pressure antinode in the cell center by the so-called primary Bjerknes force, which, for amplitudes moderate enough, counterbalances buoyancy and maintains the bubble stable against translational motion [18–21]. Observation of a stable spherical bubble also requires diffusional equilibrium, which is achieved by adequately degassing the water [1,6], down to 10–40% of the saturation concentration in the case of air [8,22,23]. The bubble must also be stable against shape instabilities, which is ensured in a given amplitude range [22,24,25].
Levitation cells owe their popularity to the fact that the radial dynamics of the trapped bubble closely follows the theoretical picture of a bubble driven by an isotropic sound field in an infinite liquid domain [22,26,27]. The latter can be reasonably modeled by a small set of ordinary differential equations, allowing an efficient scan of the parameter set [28–31]. This theory has been successfully used to explore the details of the light-emission mechanism [32].
On the other hand, a bubble oscillating in the stable SBSL regime is known to show a clear acoustic emission. The latter can be recorded by an hydrophone or a focused transducer located near the bubble [21,33]. An easier and non-invasive method consists in recording the output signal of a small piezo-ceramics glued on the side of the levitation cell [1,33]. Holzfuss and co-workers showed that an SBSL bubble had a perfectly periodic acoustic signature, constituted of a rich apigenin set of harmonics of the driving frequency [21]. It can be conjectured that this signature would be modified when a perturbing object approaches or appears sufficiently close to the bubble. Thus, real-time acoustic monitoring of the levitation experiment may allow to detect otherwise non-predictable events such as a cell or droplet passing near the bubble, or the growth of a crystal in its neighborhood. Using this information may for example allow to trigger a camera and image the event as soon as possible.

br Materials and methods During the

Materials and methods
During the experiments the variation of the contact angle caused by different vibration amplitudes of the surface was measured for each available frequency. Fig. 2 is a diagram of the experimental configuration, showing an ultrasonic transducer that provides high amplitude vibration at a given working frequency, an illumination source, and a high speed camera. On the right side of the image, a photographic detail of the assembly is shown. The following lines give a more detailed description of the experimental setup.

Results
Using the methodology described above, the contact angles were measured for each frequency and different vibration amplitudes. As already stated, the amplitudes were increased from zero, always below the atomization threshold, in steps of one tenth of the critical amplitude until a value close to this histamine-2 receptor antagonist limit. The results are shown in the Fig. 5, where each line represent an ensemble of points corresponding to different contact angles vs. vibration amplitude for each vibration frequency.
To offer a better understanding of the working methodology, Fig. 6a is, as an example, a photograph of a drop of distilled water placed on a titanium surface without vibration, and lines that determine the contact angle, θ, have been drawn. Fig. 6b shows the drop of water when the transducer tip is subjected to vertical vibrations. The contact angle in Fig. 6b is remarkably smaller than in Fig. 6a. In this example, the transducer is vibrating with an amplitude of 5μm at a frequency of 11kHz.
The data distribution suggests a linear correlation between the contact angle and the vibration amplitude, and applying a least squares method we get the straight lines of Fig. 5.
The slopes of the straight lines in Fig. 5 decrease as the vibration histamine-2 receptor antagonist frequency increases. Looking for the possible relationship between the wettability and the vibration frequency, a graph of the slopes of the curves of Fig. 5 vs. the frequency was plotted.
The points of Fig. 7 are lined up, showing an inverse dependence between the slopes and the vibration frequencies. In other words, for a given vibration amplitude, the contact angle decreases with increasing frequency, showing an increase of the surface wettability.
When the measured contact angle is plotted vs. the peak vibration velocity, a relationship between these two variables is found. Fig. 8 shows the resulting graph of contact angle versus vibration velocity for the different frequencies studied. In this graph a similar behavior between different frequencies is seen. Assuming a linear correlation between data, the slopes of the lines are similar to one another. It is important to note that the 6kHz line behavior does not follow the general trend, with this line having a lower slope.
This behavior is shown in Fig. 9, where the slope of the contact angle versus the peak vibration velocity is plotted for different frequencies. The slopes for all the frequencies are almost the same, except for the 6kHz slope, for which it is lower than those for the other frequencies studied. A possible reason for this difference would be the presence of capillary waves, hindering the measurement of the contact angle. Fig. 10 shows capillary waves with a wavelength of 250μm for this frequency. It should be noted that the length of a capillarity wave is about one-tenth the drop diameter at this frequency, affecting the measurement processes. As frequency increases, the impact of these capillarity surface waves decreases.
Despite the behavior at 6kHz, the general trend of the curves shows that the apparent wettability is proportional to the peak vibration velocity, at least for a frequency range from 11kHz to 38kHz, with an average proportionality constant of −0.707rad/(m/s). The intercept value represents the contact angle without vibrations, i.e. at rest, and has an average value of 1.189rad. With a correlation coefficient of R=−0.84. From this, an empirical relationship between these two variables can be written as:where is the apparent contact angle, measured in radians, and is the peak vibration velocity measured in m/s. This expression is independent of the vibration frequency at least in the range from 11kHz to 38kHz and corresponds only to the variation of the wettability for the Water/Ti-6Al-4V/Air interface under the specified laboratory conditions. The behavior during testing shows a dramatic increase of the apparent wettability with increasing vibration velocity. Expression (2) allows the determination of the upper wettability limit; the velocity can be increased until the value of θ became zero, and beyond this value expression (2) loses its meaning. This expression facilitates the application of the technique, but does not imply that they can consider other more general relations.

br Materials and methods During the

Materials and methods
During the experiments the variation of the contact angle caused by different vibration amplitudes of the surface was measured for each available frequency. Fig. 2 is a diagram of the experimental configuration, showing an ultrasonic transducer that provides high amplitude vibration at a given working frequency, an illumination source, and a high speed camera. On the right side of the image, a photographic detail of the assembly is shown. The following lines give a more detailed description of the experimental setup.

Results
Using the methodology described above, the contact angles were measured for each frequency and different vibration amplitudes. As already stated, the amplitudes were increased from zero, always below the atomization threshold, in steps of one tenth of the critical amplitude until a value close to this histamine-2 receptor antagonist limit. The results are shown in the Fig. 5, where each line represent an ensemble of points corresponding to different contact angles vs. vibration amplitude for each vibration frequency.
To offer a better understanding of the working methodology, Fig. 6a is, as an example, a photograph of a drop of distilled water placed on a titanium surface without vibration, and lines that determine the contact angle, θ, have been drawn. Fig. 6b shows the drop of water when the transducer tip is subjected to vertical vibrations. The contact angle in Fig. 6b is remarkably smaller than in Fig. 6a. In this example, the transducer is vibrating with an amplitude of 5μm at a frequency of 11kHz.
The data distribution suggests a linear correlation between the contact angle and the vibration amplitude, and applying a least squares method we get the straight lines of Fig. 5.
The slopes of the straight lines in Fig. 5 decrease as the vibration histamine-2 receptor antagonist frequency increases. Looking for the possible relationship between the wettability and the vibration frequency, a graph of the slopes of the curves of Fig. 5 vs. the frequency was plotted.
The points of Fig. 7 are lined up, showing an inverse dependence between the slopes and the vibration frequencies. In other words, for a given vibration amplitude, the contact angle decreases with increasing frequency, showing an increase of the surface wettability.
When the measured contact angle is plotted vs. the peak vibration velocity, a relationship between these two variables is found. Fig. 8 shows the resulting graph of contact angle versus vibration velocity for the different frequencies studied. In this graph a similar behavior between different frequencies is seen. Assuming a linear correlation between data, the slopes of the lines are similar to one another. It is important to note that the 6kHz line behavior does not follow the general trend, with this line having a lower slope.
This behavior is shown in Fig. 9, where the slope of the contact angle versus the peak vibration velocity is plotted for different frequencies. The slopes for all the frequencies are almost the same, except for the 6kHz slope, for which it is lower than those for the other frequencies studied. A possible reason for this difference would be the presence of capillary waves, hindering the measurement of the contact angle. Fig. 10 shows capillary waves with a wavelength of 250μm for this frequency. It should be noted that the length of a capillarity wave is about one-tenth the drop diameter at this frequency, affecting the measurement processes. As frequency increases, the impact of these capillarity surface waves decreases.
Despite the behavior at 6kHz, the general trend of the curves shows that the apparent wettability is proportional to the peak vibration velocity, at least for a frequency range from 11kHz to 38kHz, with an average proportionality constant of −0.707rad/(m/s). The intercept value represents the contact angle without vibrations, i.e. at rest, and has an average value of 1.189rad. With a correlation coefficient of R=−0.84. From this, an empirical relationship between these two variables can be written as:where is the apparent contact angle, measured in radians, and is the peak vibration velocity measured in m/s. This expression is independent of the vibration frequency at least in the range from 11kHz to 38kHz and corresponds only to the variation of the wettability for the Water/Ti-6Al-4V/Air interface under the specified laboratory conditions. The behavior during testing shows a dramatic increase of the apparent wettability with increasing vibration velocity. Expression (2) allows the determination of the upper wettability limit; the velocity can be increased until the value of θ became zero, and beyond this value expression (2) loses its meaning. This expression facilitates the application of the technique, but does not imply that they can consider other more general relations.

Introduction Ganoderma lucidum G lucidum

Introduction
Ganoderma lucidum (G. lucidum) or Ling zhi has been therapeutically considered to be one of the important herbs in the Traditional Chinese Medicine (TCM).The fruiting body, mycelia, and spores of G. lucidum contain approximately 400 bioactive compounds. Diverse groups of these bioactive compounds such as triterpenes, polysaccharides, proteins, nucleotides, nucleosides, metals etc. with different pharmaceutical activities have been isolated from this species [1,2]. Among these bioactive compounds, polysaccharides have attracted the attention of many researchers due to their potential ability to treat a wider number of diseases [3]. Among different types of polysaccharides isolated from G. lucidum[4,5], the linear β-glucan with a backbone (1-3) and varying degree of branching at C6 position was one of the major contributors of mushroom bioactivity [2]. In particular, in the living organisms, polysaccharides could be used as anti-oxidants to prevent the cellular damages caused by the free radicals resulted from oxidation reactions during the process of pteryxin generation. Considerably, these free radicals are harmful to the human body as they induce potential damages i.e. tissue loss, inducing certain diseases, manipulation of protein and ageing [6]. Among the natural resources to obtain these antioxidants, isolation of polysaccharides from G. lucidum has been found to possess significant capability to inhibit the formation of free radicals besides having higher scavenging activity [3,6,7].
Utilization of ultrasound to assist the extraction of active ingredients from natural resources has many advantages over other conventional techniques. Ultrasound assisted extraction has been well proven as a green technology and has enhanced the extraction process in different green aspects. Besides reducing the extraction time and solvent usage which are considered to be the major limitations of any extraction process, lesser energy consumption, higher yield of production, and higher preservation of bioactivity of the separated biomolecules due to lower extraction temperatures could be added as merits of ultrasonic extraction [8–10].
Many studies have reported on the aspects of improving the extraction with the application of ultrasound cavitation. Due to the transient cavitation, bubbles collapse asymmetrically near the solid surfaces and create micro-jets that are strong enough to disrupt the cellular materials during the extraction process. Consequently the mass transfer rate will be intensified i.e. a significant and an increased release of both the intracellular and cell-wall materials that diffuse into the extracting solvent. However, the successful application of ultrasonic extraction relatively depends upon the optimum operating conditions and the matrix of subjected plants [11]. Hromadkova et al. (2002) reported on the extraction of polysaccharides from the insoluble plant residues that were obtained after the preparation of medicinal tincture from the roots of Valeriana officinalis L[12]. A remarkable influence of ultrasound in increasing the extractability of cell-wall type polysaccharides (xylan, mannan, and glucan) due to cracking, peeling the outer surface cell-layers, and size-reduction of the solid plant matrix has been observed. However, the sugar composition of the resulted polysaccharides showed that the easily accessible polysaccharides (pectic and starch-based) were degraded due to the damage from cavitational implosion after subjecting them to ultrasound for a longer time (2h) with a power intensity of 1W/cm2. Thus, the woody structure of G. lucidum and the operating ultrasonic parameters significantly affect the efficiency of extraction i.e. to obtain a higher yield and a higher antioxidant activity of the extracted polysaccharides.
To the best of our knowledge, G. lucidum mushroom that has been artificially cultivated in Malaysia was not investigated yet for the extraction and characterization of polysaccharides content. Besides, the (1-3; 1-6)-β-d-glucans content and antioxidant activity of the extracted polysaccharides from this artificial source have not been reported. Owing to this, the ultrasonic extraction has been adopted in this investigation which was then compared with contemporary methods of extraction such as soxhlet and hot water extraction for the characteristics and antioxidant properties of the extracted polysaccharides.

dpp-4 inhibitor br Introduction Elemental tellurium Te is a p type

Introduction
Elemental tellurium (Te) is a p-type semiconductor with direct narrow band gap dpp-4 inhibitor of 0.35eV [1]. It has a wealth of useful properties including nonlinear optical responses, photoconductivity, and thermoelectric properties, which result in their potential applications in electronic and optical electronic devices [2–6]. Additionally, Te is considered as important materials for CO, NO2 and ammonia gas sensors [7,8], catalytic activities [9], and removal of mercury ions [10]. Therefore many investigations have been employed for this substance and various Te nanostructures such as nanotubes [11], nanowires [12] and nanorods [13] were prepared by many approaches such as electrochemical deposition [14], microwave [15], hydrothermal [16], and physical evaporation method [17]. Nevertheless, the preparation of Te nanostructures via wet chemistry routes is currently using. For example, Cao et al. synthesized single-crystalline Te nanowires under hydrothermal conditions at 130°C and 170°C [18]. Te nanotubes and nanorods have been prepared via a hydrothermal method at 120°C for 12h by Zhu et al. [19]. Synthesis of trigonal Te (t-Te) nanorods, nanowires and nanobelts at 150°C under refluxing conditions in ethylene glycol and diethylene glycol for 2h was reported by Gautam and Rao [20]. Xia and Mayers [21,22] have successfully synthesized a series of uniform Te nanowires through the reduction of H6TeO6 or TeO2 in different solvent systems by N2H4·H2O and a refluxing process. However, there are some other challenges for preparation of this material that require more investigations in this scope. For instance, various Te sources such as TeCl4 is rapidly hydrolyzed in water and bulk TeO2 is formed and thus converting TeO2 to Te strong reducing agent such as hydrazine needs [6]. Furthermore, tellurium inherently tends to form 1-D structures and there are many reports on it [6,23,24]. However, other morphologies are also important. Herein, with a simple and novel sonochemical method in which TeCl4 is easily reduced by ultrasonic irradiation in methanol, tellurium nanoparticles were synthesized. TeCl4 is dissolved in methanol and are not hydrolyzed in other words. So, TeO2 is not form and ultrasound waves can produce tellurium nanoparticles without the need for secondary reducing agent. Also, by performing reaction in an alkaline environment TeO2 nanostructures can be easily produced. According to our knowledge, keratin is the first time that without secondary reducing agent Te4+ are reduced to Te. Recently, the ultrasonic process as a fast, convenient, and economical method has been widely used to generate novel nanostructure materials under ambient conditions [25–28]. The chemical effects of ultrasound arise from acoustic cavitation, which is the formation, growth, and implosive collapse of bubbles in a liquid. According to hot spot theory, very high temperatures (>5000K) are obtained upon the collapse of a bubble. Since this collapse occurs in less than a nanosecond, very high cooling rates (>1010K/s) are also obtained [29–31]. These extreme conditions can drive a variety of chemical reactions to fabricate nano-sized materials. The effect of preparation parameters such as ultrasonic power, irradiation time, solvent, HCl, NaOH, and surfactant on the morphology and particle size of as synthesized tellurium was also investigated.

Experimental

Results and discussion
a and b provide a comparison of typical XRD patterns of product derived in the absence and presence ultrasonic irradiation (samples 1 and 2, respectively). The diffraction peaks, observed in Fig. 1, can be indexed to tetragonal phase of TeO2 (space group: P41212, JCPDS No. 76-0679 with cell constants a=b=4.8052 Å, c=7.6021 Å). As b shows, pure TeO2 is obtained under ultrasonic irradiation while in the absence of waves, impurities such as TeO3 (JCPDS No. 20-1240) and Te (JCPDS No. 81-1609) also appear (a). The sharp diffraction peaks manifestation in b shows that the obtained TeO2 under ultrasonic irradiation have high crystallinity. From XRD data, the crystallite diameter (Dc) of TeO2 obtained under ultrasonic irradiation (sample 2) was calculated to be 23nm using the Scherer equation [30]:where β is the breadth of the observed diffraction line at its half intensity maximum, K is the so-called shape factor, which usually takes a value of about 0.94, and λ is the wavelength of X-ray source used in XRD. a and b show the SEM images of products obtained in the absence and presence of ultrasonic irradiation (samples 1 and 2, respectively). As can be seen, in the absence of waves bulk structure has been produced while performing the reaction under ultrasonic the particles have become smaller that self-assembled to form octagon microstructures. When TeCl4 reacts with water, it will immediately form TeO2, owing to which they appear as bulk.

When a cavitation bubble cloud changes from one structure

When a cavitation bubble cloud changes from one structure to another, the number of cavitation bubbles also changes. Fig. 11 shows the process of a gas bubble splitting to a cluster of cavitation bubbles when the transducer is just turned on. Fig. 12 shows the coalescence of cavitation bubbles when the transducer is just turned off. The special structure of thin liquid layer makes it doable to count the number of cavitation bubbles. The two examples illustrate the influence of acoustic intensity on the number of cavitation bubbles.
Fig. 13 shows the variation of bubble numbers in a cluster when acoustic intensity is nearly constant. The lens was focused on a bubble cluster, which is well-defined and numerable when the bubbles expand to their maximum volume. Some cavitation bubbles may split, merge orannihilate, some bubbles may be too small to be visible, and some bubbles may suddenly grow to visible size. All of these factors influence the number of cavitation bubbles in an acoustic period.
There are two opposite physical processes: bubble production and bubble disappearance, which may coexist in the cavitation bubble cloud. The rate of bubble production is defined as the increased number per unit of time relative to the original bubbles number. The increased number may be from fragmentation, suddenly growing up to sufficient size to be visible of cavitation bubbles or other possible way [21]. The rate of bubble disappearance is defined as the decreased number per unit of time relative to the original bubbles number. The decreased number may be from coalescence, annihilation, dormancy (It means that cavitation bubbles become too small to be visible and look like inactive, but they do not annihilate over several cycles and some of them may be active after a while.) or other EPZ-6438 cost possible way. If the rate of bubble production equals to the rate of bubble disappearance during a period of time, then the number of cavitation bubbles remains unchanged, and cavitation structure is steady or quasi-steady. A shows the transformation and stability mechanism of cavitation structures. The horizontal coordinate represents the acoustic power penetrating the cavitation cloud. The longitudinal coordinate represents the total number of cavitation bubbles in the cavitation cloud. When experimental conditions have a perturbation, the rate of bubble production and disappearance loses balance for a moment, and then recover balance under a EPZ-6438 cost mechanism (as shown the arrows surrounding steady-state A in the A). “a” represents that the rate of bubble production is greater than the rate of bubble disappearance, the number of cavitation bubbles increases, the area of cavitation cloud increases; “b” represents that the acoustic power applied to the liquid decreases due to the shielding effect of cavitation cloud. “c” represents that the rate of bubble disappearance is greater than the rate of bubble production, the number of cavitation bubbles decreases due to the decrease of acoustic power applied to liquid. “d” represents that the acoustic power applied to the liquid increase due to the weakening of shielding effect. The whole process tends to self-stabilize the system and keep the state stable.
If the rate of bubble production is not equal to the rate of bubble disappearance, then the number of cavitation bubbles changes, cavitation bubble cloud may evolve into another kind of cavitation structure. The steady-state A, B, C and D in A are four steady states of cavitation structures under different conditions, the rate of bubble production and disappearance keeps balance, the total number of cavitation bubble remains unchanged. When the experimental conditions are altered, the rate of bubble production and disappearance loses balance, the cavitation structures vary correspondingly, and the variation is relative reversible. The increase and decrease of bubble production and disappearance rate is related to the changes of acoustic intensity, bubble nuclei and boundary. For example, steady-state A to steady-state B is the transformation caused by the decrease of acoustic intensity. The rate of bubble disappearance is greater than the rate of bubble production, cavitation bubble number decreases. Steady-state A to steady-state C is the transformation caused by the increase of nuclei. The rate of bubble production is greater than the rate of bubble disappearance, cavitation bubble number increases. However, the increase of cavitation bubble number enhances shielding effect of cavitation cloud; hence acoustic power applied to liquid weakens. Steady-state A to steady-state D is the transformation caused by the increase of liquid layer thickness (boundary). The rate of bubble disappearance is greater than the rate of bubble production, cavitation bubble number decreases. The acoustic power penetrating the cavitation cloud increases [19]. This is because that the boundary effect is weakened when liquid layer thickness increases, which facilitates the migration and coalescence of cavitation bubbles under the action of second Bjerknes force.

The Dimensional edge diffraction coefficient for a diffracted longitudinal

The 2-Dimensional edge diffraction coefficient for a diffracted longitudinal wave, when a longitudinal wave is incident at a crack-tip in a homogeneous isotropic solid, is given by [13,16]wherewhere α is the incident longitudinal wave angle, β is the diffracted longitudinal wave angle and .is the ratio between longitudinal and Rayleigh wave velocities. K+(γ) is an integral ARQ 197 given byRange-dependent diffracted wave amplitude in a homogeneous isotropic material is expressed aswhere is the wavelength of longitudinal wave and R is the radial distance measured from the crack-tip to the receiver position.
The material properties for the homogeneous isotropic steel material are presented in Table 2. Fig. 6 shows the comparison of HFDM based diffracted wave amplitudes with GTD results at different observation angles (i.e. observation angle is measured based on the receiver position and edge of the crack). It can be seen from Fig. 6 that the HFDM results agree quantitatively well with GTD results. However, minor variations are observed between HFDM and GTD calculations. Generally, HFDM considers the finite- dimension effects of the transducer and the final diffracted wave amplitude at the receiver is obtained by superposition of surface displacements produced by virtual sources in the unblocked region of the crack vertical plane. Consequently, side lobe formation in the HFDM-based amplitudes can be noticed in Fig. 6. Whereas in case of GTD calculation, only a single ray is allowed to propagate from the finite dimension transducer to interact with the crack-tip. In addition, the diffracted wave amplitudes obtained from the GTD shows singularity at the shadow boundaries and these singularities do not appear in the HFDM results (see Fig. 6).

Comparison of HFDM simulation results with experiments

Conclusions
In this paper, a novel Huygens–Fresnel Diffraction Model (HFDM) has been developed to simulate the ultrasonic time-of-flight diffraction technique (TOFD) in 2D geometries quantitatively. The far-field wedge refracted beam profiles for longitudinal and shear vertical waves were modelled using an array of load points. The simulated results were compared with laboratory experimental results on 10mm thick aluminium specimens with 2mm and 4mm top surface-breaking crack lengths using 70° shear wave insonification and 55° P wave insonification. Additionally, the validations were performed for both symmetric and asymmetric TOFD configurations. The model predicted relative amplitudes and transit times of the diffracted wave, lateral wave and the back-wall reflected wave signals agree quantitatively very well with the measurements. Other configurations such as bottom surface-breaking cracks and embedded cracks pose no additional model-related difficulties.

Acknowledgements

Introduction
Phononic crystals are periodic elastic composites [1,2]. The band structures of an elastic wave prorogating in phononic crystals are similar to those of an electromagnetic (EM) wave in photonic crystals [3,4], showing the feature of pass and stop bands. Within stop bands, waves cannot propagate. Such band structures facilitate various applications of phononic crystals, e.g., wave guide, sonic filters, vibration suppression, sound isolation, resonant cavities, acoustic cloak and hyperlens, etc. [5–11] and have promoted intensive interests from scientists and engineers [1–2,5–21].
Piezoelectric materials can generate electric charge upon mechanical loading through piezoelectric effect and vice versa [22]. Recently, periodic piezoelectric composites and their acoustic band structures have been investigated in a number of studies [23–29]. It is found that, in general, the piezoelectric effect can be applied to alter the band gap. In addition, the effects of initial stress have also been investigated [23,29]. In most these studies, the electric field is assumed to be quasi-static. As a result, there is no electromagnetic (EM) wave and only elastic wave exists in these composites. In fact, Southern blotting is natural to consider the electric field to be dynamic and, consequently, piezoelectric composites are expected to have a dual role as a phononic crystal and a photonic crystal, as that of optomechanical crystals [30]. So far, limited studies on acoustic and EM waves in periodic piezoelectric composites are available [31–38]. Piliposian and his coworkers [31,32] investigated the propagation of coupled SH elastic and EM waves in a one dimensional periodic piezoelectric composite. The full system of Maxwell’s equations was considered. It is noted that the ARQ 197 crossing of the dispersions of photons and phonons in the long-wavelength limit may indicate a strong coupling of EM wave and lattice vibration, that is, phonon-polariton in periodic piezoelectric composites [33–36]. The problem studied by Piliposian and Ghazaryan [31] was re-visited by Xu et al. [37]. It was found that phonon-polariton occured not only near the center of the Brillouin zone (in the long-wavelength limit) at acoustic frequencies but also in the whole Brillouin zone at optical frequencies, which was confirmed by Ref. [38]. This feature of phonon-polariton makes it possible to manipulate light in a specific path, and new opto-acoustic devices might be designed such as novel laser geometries, optical detection and nondestructive evaluation [31,33].

Up to now research on

Up to now, research on the system with the resonators inside the plate has seldom been reported. Yu and Chen studied lamb waves in two-dimensional phononic crystal slabs with neck structure [42]. With the resonators depositing inside, the whole structure will be lighter as some material is removed, and meanwhile the volume is smaller. Therefore, the study on the propagation of Lamb waves in a PC plate with the resonators inside is more interesting. But, there is no report on the phononic crystal with two resonators.

Model and formulation
A kind of structure of PCs of an isotropic solid with two resonators in a square lattice is proposed. As shown in Fig. 1(a) and (b), the PC structure considered here is a slab with two rectangular inclusions embedded periodically along the X–Y plane. The inclusions are not connected with the slab directly but linked through some rectangular connectors. The structure is infinite in the Z-direction and the axes of the resonators are parallel to the surface of the PCs. The sidelength of the Model 1 is lattice constant a, and the four sides are equal in length. Inside the Model 1, the sidelength of hollow part is c. In the same cavity, there are two separate resonators, their lengths and widths are k1, w1, k2, and w2 respectively. The connector geomotry parameters are h1, b1, h2, and b2. The corresponding irreducible Brillouin zone of unit cell is shown in Fig. 1(c).
In the present work, to investigate the gap characteristics of these order KU-60019 new kinds of PC structure, a series of calculations on the dispersion relationship and transmission spectra are conducted with FEA method based on the Bloch theorem [43–46]. For the calculation of the dispersion relations of the proposed structure referring to an infinite system, the governing field equations are given bywhere ρ is the mass density, is the displacement, t is the time, are the elastic constants, and (j=1,2,3) represents the coordinate variables x, y, and z respectively.
Since the infinite system is periodic along the x and y directions simultaneously, according to the Bloch theorem, the displacement field can be expressed aswhere k=(,) is the wave vector limited to the first Brillouin zone of the repeated lattice and (r) is a periodical vector function with same periodicity as the crystal lattice.
In the present work, the finite element method (FEA) is used to calculate the structures of the PCs. a series of calculation on the dispersion relations and transmission spectra are conducted with the FEM. Due to the periodicity of PCs, the calculation can be implemented in a representative unit cell. The eigenvalue equations in the unit cell can be written aswhere U is the displacement at the nodes and K and M are the stiffness and mass matrices of the unit cell, respectively. The Bloch theorem of Eq. (2) should be applied to the boundaries of the unit cell, yieldingwhere r is located at the boundary nodes and a is the vector that generates the point lattice associated with the phononic crystals.
COMSOL Multiphysics 3.5a is utilized to directly solve the eigenvalue Eq. (3) under complex boundary condition of Eq. (4).
In the present work, the structural mechanics module operating under the 2D plane strain application mode (smpn) is applied. The free boundary condition is imposed on the surface of the hole, and the Bloch boundary conditions on the two opposite boundaries of the unit cell. The unit cell is meshed by using the default triangular mesh with Lagrange quadratic elements provided by COMSOL. Eigenfrequency analysis is chosen as the solver mode, and the direct SPOOLES is selected as the linear system solver. For the calculation of the transmission spectra, a finite system must be defined. In the process of using COMSOL simulation, incentive conditions should be put on the left side of the unit throughout the research. We consider here the structure being finite in the x direction that contains N units. In the y direction, the periodic boundary conditions are still used to represent the infinite units. In this case, a finite array structure composed of N×1 units is modeled for the calculation. The plane waves with single-frequency, supplied by the acceleration excitation source, are incident from the left side of the finite array and propagate along the x direction, and the corresponding transmitted acceleration value is recorded on the right side. The transmission is defined aswhere a0 and are the values of the transmitted and incident acceleration, respectively. By varying the excitation frequency of the incident acceleration, the transmission spectra can be obtained.

rgs protein The experimental apparatus system has been successively

The experimental apparatus system has been successively tested, measuring α of two phantoms with different thickness and same chemical composition. In Fig. 10, their attenuation coefficients have been shown as a function of frequency with interpolating curves given by Eq. (26) and the a parameter fixed to 0 [35].
Both gels follow the trend expressed by Eq. (26), that has been already observed in tissues and other biological media [35] and their parameters α0 and b, listed in Table 3, result consistent within their uncertainties.
Consequently to preliminary tests, the attenuation measurement method has been applied to investigate TMM samples previously described. Obtained attenuation coefficients versus frequency at =22°C and respective interpolating curves are shown in Fig. 11 (TMM 1 and TMM 1a) and in Fig. 12 (TMM 2, TMM 2a and TMM 2b), while fitting parameters referred to Eq. (26) are listed in Table 4.
Observing Figs. 11 and 12, Phytagel based gels result to be more attenuating with respect to the Agar based TMMs. This difference could be ascribed to the different mechanism of agglomerates formation given by long chain molecules formed during the polymerization phenomenon. Indeed, the interaction of the cationic species (Ca++ in our case) with the carboxylic group of Phytagel molecules could lead to the formation of double helical rods longer than those obtained with Agar and to a possible increase of the hydrodynamic radius of Phytagel molecules. As it is reported in literature [22], ultrasonic rgs protein of gel, formed by polysaccharide molecules, is given substantially by the interactions of ultrasonic waves with junction zones of double helical rods or aggregates of junction zones.
To increase the attenuation of TMMs, the dispersion of inert solid particles into the polymer matrix [36] has been used. In our case, the addition of kieselghur and SiC, as reported for TMM 2b, has allowed to obtain the most attenuating sample among those studied. Its attenuation coefficient, at 1MHz, is (0.93±0.09) dB·cm−1, while the value (0.51±0.04) dBcm−1 has been obtained for the sample TMM 2a and (0.12±0.01) dBcm−1 for the sample TMM 2. Changing TMMs composition, significant differences have been obtained in sample attenuation coefficients. With the aim to realize a specimen able to simulate the characteristic attenuation of a soft tissue, such as liver or kidney [31], obtained results have been promising.
The uncertainty budget of the attenuation coefficient has been evaluated combining contributions of sources listed in Table 5.
As it can be observed, almost all the budget amount is due to the thickness measurement. The thickness measurement also affects the speed of sound determination, which represents the second main source of α uncertainty. Thus, efforts will be addressed to the improvement of d measurement by means of a high resolution height gage joined to a feeler pin. Anyway, part of this uncertainty could not be deleted as linked to the intrinsic indeterminacy of the sample.
The temperature stability of the experimental system over a measurement is of ±0.05°C, which means a contribution of 0.22% to α relative uncertainty, while the thermometer calibration contribution results entirely negligible (⩽3·10−5°C). The linearity of the measurement system, which includes both the nonlinear loss of water and the linearity of the electrical system, has been evaluated in the frequency range used for measurements. The maximum residual observed from a linear behavior has been of 0.34%, which has been included in the uncertainty balance.

Acknowledgments

Introduction
Lipid particles have frequently been utilized as a preferred carrier for targeted facilitation of biological reaction in the area of biochemistry and drug delivery. Several positioning techniques have thus been developed to spatially confine individual lipid objects by means of dielectrophoresis, optical tweezers, and acoustic waves. Polarizable liposomes suspended in aqueous media were manipulated with dielectrophoretic force that was originated from alternating current (AC) electric fields via intricate microelectrodes [1]. Dielectric particles in a fluid suspension are either attracted to or pushed away from a region of high intensity gradient by induced dipole moments, depending on their size and permittivity constant (or called the Clausius–Mossotti factor). Optical tweezers delivered single liposomes containing potassium chloride (KCl) to cultured neuronal cells for chemical stimulation, where substantial change in calcium ion (Ca2+) concentration indicated the depolarization of neurons by KCl [2]. A traveling laser beam is tightly focused through an objective of high numerical aperture, interacting with an optically transparent dielectric particle e.g., cells, polystyrene beads, etc, whose refractive index is greater than that of a surrounding medium. When a momentum transfer occurs between the particle and the incident beam, the particle is held up at the focus by optical radiation force acted on it. Lipid particles were separated from whole blood suspension and subsequently trapped at a half-wavelength interval in 2MHz ultrasonic standing wave fields [3]. Two waves of the same wavelength and amplitude that are formed by a transducer–reflector pair propagate in opposite directions, manipulating a group of particles over parallel stationary planes of either node or anti-node.