br Acknowledgements The authors wish

Acknowledgements
The authors wish to thank, in order of acquisition, the Mediterranean Office for Youth Program (MOY, call 2011-2014), by means of which Stefanos Giannakis has received a PhD mobility grant (MOY Grant No. 2010/044/01) in the joint Environmental Engineering Doctoral Program. Also, the Swiss Government for the Swiss Government Excellence Scholarship, by means of which Stefanos Giannakis has received a Research Visit fellowship (No. 2012.0499). Finally, Stefanos Papoutsakis was funded by the Swiss-Hungarian Co-operation Program “Sustainable fine chemical, pharmaceutical industry: screening and utilization of liquid wastes – Innovative approaches for the abatement of industrial/toxic waste in aqueous effluents”.

Introduction
Advanced oxidation processes (AOPs) are a set of technologies which lead to the oxidation of pollutants by provoking the formation of highly reactive oxygen species, especially OH radicals. Among the most well known AOPs is the photo-Fenton process, a non-selective photocatalytic process in which OH is generated during the oxidation of Fe2+ to Fe3+ by H2O2. Application of ultraviolet light at frequencies below 400nm (present within the spectrum of solar radiation) can regenerate the Fe2+, greatly increasing the efficiency of the process [1–3]. It has been studied extensively for the treatment of many types of contaminants [4,5] at relatively low cost [6]. As such, the photo-Fenton process can provide the industry with a powerful tool to treat wastewater with clean Lomefloxacin HCl cost from the sun [7]. However, the process is not a universal remedy as it can demand large amounts of H2O2 and its dependence on light, can be a limiting factor in sunshine deprived regions. Iron also tends to form insoluble aqua complexes at pH above 4, sometimes necessitating either pH adjustment or the addition of iron-chelating agents for increasing its solubility in neutral pH [8]. In order to minimize treatment time, reagent consumption and costs, significant investigative efforts have been made towards the development of hybrid processes such as biological treatment/photo-Fenton [9,10], electro-and photoelectro-Fenton [11], and ultrasound/photo-Fenton [12]. It is this latter system that will be the focus of this study.
Ultrasonic (US) treatment is another AOP that has been gaining interest in the last years. When ultrasound is applied to a liquid medium, cavitation bubbles are formed. After a series of expansion and compression cycles, these bubbles violently collapse to generate very high temperatures and pressures concentrated in one localized ‘hot spot’ [13].The surrounding liquid will consequently quench it within a millisecond timeframe (cooling rates in excess of 1012K/s [14]), generating extreme gradients of both pressure and temperature. This quasi-adiabatic energy process has profound effects on Lomefloxacin HCl cost the surrounding liquid [15] as well as the chemical species found in its vicinity. It has been reported that reactive radicals such as OH [16] can be generated via the thermal dissociation of water [15] during bubble collapse. As the OH radical has a short lifetime [17], hydrophobic compounds are expected to be preferentially oxidized near the bubble/bulk interface due to their close proximity to the cavitation bubble [18–20]. Additionally, if their vapor pressure is high, they may enter the bubble and be directly pyrolyzed during its implosion. It has also been shown at laboratory scale that ultrasound can promote the generation of H2O2 which could be utilized during the photo-Fenton reaction [21]. It is however unverified whether this generation remains significant at pilot-scale. H2O2 maintains a complex role in pure ultrasonic processes as well, acting both as a source of free radicals by a dissociation process, as well as a radical scavenger [22].
High ultrasound frequencies are widely regarded as more efficient in the destruction of organic pollutants, with several studies pointing towards an optimal frequency region between 350 and 500kHz, with representative reported values at 358kHz [23], 506kHz [24] and 582kHz [25]. Due to the high cost implicit to the use of pure ultrasound treatment, there is a strong interest in combining it with other AOPs and taking advantage of beneficial synergistic effects for lowering treatment costs.

The IR spectrum of the nano structures

The IR spectrum of the nano-structures produced by the sonochemical method and of the bulk material produced by the solvothermal method were compared with each other in Fig. 2. The structure of Afatinib Supplier 1 was characterized by single-crystal X-ray diffraction techniques [50]. The molecular structure of the fundamental building unit for 1 is shown in Fig. 3. The asymmetric unit consists of four Zn(II) atoms, four BDC2− ligands, four bpta linkers, five DMF, and three water guest molecules. The framework is constructed from a six-connected dinuclear Zn2N4O6 node, which is octahedrally bound to four BDC ligands and two double-bpta-deckered pillars. Each BDC2− ligand acts as a μ3-bridge to link three Zn(II) atoms, in which one carboxylate group exhibits a μ2-η1:η1-bridging coordination mode, while the other adopts a monodentate structure (Fig. 3).
Fig. 4 shows the simulated XRD pattern from single crystal X-ray data of compound 1 in comparison with the XRD pattern of the as synthesized nano-structure of compound 1 by the sonochemical process. Acceptable matches were observed between the simulated and experimental XRD patterns. This indicates that the compound obtained by the sonochemical process as nano-structures is identical to that obtained by single crystal diffraction. The significant broadening of the peaks indicates that the particles are of nanometer dimensions.
The morphology and size of compound 1 prepared by the sonochemical method was characterized by scanning electron microscopy (SEM). Fig. 5 shows the SEM of the compound 1 prepared by ultrasonic generator 12W in concentration of initial reagents [Zn2+]=[BDC]=[bpta]=0.04molL−1. Also different concentrations of zinc(II), 1,4-benzenedicarboxylate and N,N′-bis(4-pyridinyl)-1,4-benzenedicarboxamide solution (0.01 and 0.006molL−1) were tested (Figs. 6 and 7). In order to investigate the role of concentration of initial reagents on the nature of products, reactions were performed with three different concentrations of initial reagents. Comparison between the samples with different concentrations shows that high concentrations of initial reagents decreased particles size. Thus, particles sizes produced using lower concentrations of initial reagents (0.006molL−1, Fig. 7) are bigger than particles size produced using higher concentrations (0.04 and 0.01molL−1, Figs. 5 and 6, respectively). More interestingly that, as shown in Fig. 7, decreasing of concentration of initial reagents ultimate to prepared rod-like nano-structure compound 1 (Fig. 7). The morphologies and size of nano-structure of the as-prepared samples for different reaction times were characterized by SEM. Fig. 8 shows the SEM image of compound 1 with reaction time of 30min (Zn(II)=BDC=bpta=0.006molL−1, 12W). The results show that the size of the nanoparticles increased with increasing reaction times. Thus, smaller particles (for 15min, see Fig. 7) were achieved by sonocrystallization at shorter times when compared with 30min (Fig. 8). To investigate the role of power ultrasound irradiation on the nature of products, reactions were performed under diverse power ultrasound irradiation too (Zn(II)=BDC=bpta=0.006molL−1, 12 and 24W). Comparison between the samples with different powers ultrasound irradiation shows that increasing of power from 12 to 24W leads to decreasing of sizes of the nanoparticles (Fig. 9). Table 1 gives an overview of the comparison of the concentration of initial reagents, times effect and different powers of ultrasonic irradiation on the morphologies and sizes of nano-structure of the compound 1.
Thermogravimetric analysis of 1 showed that guest molecules are eliminated from the network (calcd 16.1%; found 16.5%, which correspond to loss of 20 DMF molecules and 12 H2O molecules per unit cell) when the temperature is increased from room temperature to about 270°C [50].

Conclusions
Nanoparticles and nanorods of porous metal–organic framework, [Zn4(BDC)4(bpta)4]·5DMF·3H2O (1), (bpta=N,N′-bis(4-pyridinyl)-1,4-benzenedicarboxamide, BDC=1,4-dicarboxylate, DMF=N,N-dimethylformamide) have been synthesized under ultrasound irradiation. Structural information of the nanoparticles was compared with the structural information of crystals of compound 1. Morphology and sizes of the nano-structures were investigated in different concentrations of initial reagents, different powers of ultrasonic irradiation and various reaction times. Results show an increase in the particles size as the concentrations of initial reagents is decreased. It is an interesting point that low concentration of initial reagents leaded to rod-like nano-structures morphology. Also the shorter reaction times and using of different powers of ultrasonic irradiation lead to decreasing the size of nano-structures.

br Local ablative therapies This broad category

Local ablative therapies
This broad category includes those modalities that employ different forms of energy, delivered “in situ”, with the common goal of targeted tissue destruction. Chemical, thermal and electrical energy sources have been vigorously used, researched, developed, improved and clinically deployed in the last several years. Chemical ablation is the oldest percutaneous technique that has been broadly performed using agents such as ethanol or acetic niclosamide (percutaneous ethanol injection, PEI), which destroys tumor cells within the targeted tissue by induction of coagulative necrosis. However, such chemical substances, when injected percutaneously through thin needles, can diffuse into nearby tissues, which may increase the risk of drug diffusion into the arterial system and cause harmful complications. Neverthless, this technique has had low procedural complication rate and very promising results in terms of local control for treating capsulated HCC nodules that are less than 5cm. 5-year overall survical (OS) is at 47% and 29% respectively, for Child A and B cirrhotic patients. In the treatment of single infiltrating or multiple encapsulated tumors, the injection of chemical substances has shown least efficacy, mainly due to the absence of a peripheral capsule which can retain the chemical agents within tumor tissues [4]. The same issue could probably account for the unsatisfactory results when this technique is employed for treating liver metastases.
Chemical ablation has been replaced by newer technologies, based on induction of temperature variations: both increase and decrease, until the desired cytotoxic level is achieved within the targeted tissues. When heat is applied and maintained for sufficient time, over a target temperature, tissue ablation is achieved. Usually, a temperature less than −40°C or higher than 60°C, the onset of cell destruction is almost instantaneously via the induction of proteins denaturation or plasma membrane collapse due to ice crystal formation. Complete necrosis can be induced in almost all tissue types at such extreme temperatures. When reaching a temperature near to 50°C, cell death related to microvascular thrombosis, ischemia, and hypoxia may occur [5]. At temperatures slightly more than −40°C cells cool off slower and are susceptible to cell death from osmotic shock. Ice formation outside the cells, induces a hyperosmotic extracellular space with cell dehydration and, upon thawing, a reversal flux inward the cell, inducing cell swelling and membrane rupture [6].

Radiofrequency ablation
Radiofrequency energy represents the most well studied technology and the main reference for the evaluation of other more recently developed ablative techniques. When RF energy is applied, an oscillating electrical current flows through the body between electrodes in a simple circuit in which tissues, being weak electrical conductors, represent the resistive element. Thus, ionic agitation is induced in tissues around interstitial electrode and resistive heating is produced in the areas closest to the interstitial probe. As a result, tissues in proximity to the electrode are subjected to the highest current and thus a greater rise in temperature than tissues further away from the probe that are heated mostly via thermal conduction [7]. Radiofrequency ablation has emerged as the standard technique for local tumor treatment and has demonstrated better survival than PEI. Cho et al. in a recent meta-analysis of RCTs on small HCC treatment reported better local control and significant improvement in 3-year survival with RFA when compared to PEI (odds ratio 0.477, 95% confidence interval 0.340–0.670; P<0.001) [8]. The main limitations of RFA are the dimension of lesions to be treated, the “heat sink effect” produced by main vessels close to the tumor and the possibility of high major complication rate when used for sub-capsular lesions and when bile duct is in the proximity. Livraghi et al. [9] reported the safety of RFA in liver malignancies in a multicenter study involving 3500 patients: low mortality (0.3%) and low morbidity rate with major and minor complications were observed in 2.2% and less than 5% of patients, respectively. This large cohort study has established percutaneous RFA as a safe and relatively low-risk procedure.

The ultrasound assisted modification of silicon plates in the

The ultrasound-assisted modification of silicon plates, in the form of both crystalline silicon wafers and amorphous silicon deposited onto glass, were studied [12]. In general, the interaction of cavitation bubbles with the silicon surface results in mechanical and chemical modification. As was already mentioned (see Table 1), the ultrasonic modification of solids is known to be controlled by various sonication conditions, including the intensity and duration of sonication, the solvent, and the concentration and size of the sonicated species, oxidants, and reducing agents involved. The important innovation we introduce in our work [12] is the addition of hydrogen donors, such as in aqueous solutions magnesium particles or sodium borohydride, during ultrasonication, which has a dramatic influence on the process. The sonication of silicon species in water (Fig. 9), that does not contain a hydrogen donor, results in the formation of an oxidized surface caused by the 4-aminopyridine of the silicon by-products of water sonolysis. The samples are characterized by a slight increase in their surface roughness and the absence of photoluminescence. The hydrogen donors slow down the surface oxidation processes, which are brought in by free radicals formed during water sonolysis, and stabilize the porous structure through the formation of silicon-terminated bonds. In this case, Si–H bonds could be formed as an alternative to, or together with, Si–O bonds. The illustration in Fig. 9a, based on a 3D reconstruction of TEM and μ-confocal measurements of the surface after high-intensity ultrasonic exposure, shows our general concept of a single-step “green” method for the construction of surfaces with different porosities. Without a reducing agent present during modification in water, neither porous nor luminescent structures were observed. However, in the presence of a reducing agent, luminescent structures with a range of porosities (25–40% in water, 60–70% in water/alcohol mixtures, and 40–50% in an ionic liquid) were detected. Furthermore, the differences in porosities correlate with differences in photoluminescence (green or red).
Moreover it was shown [12,50] that ultrasonic treatment (20kHz, 57W/cm2) affects the surface crystal structure (Fig. 9b–d, 4-aminopyridine insets): (i) provides amorphization of crystalline structures; and (ii) alternatively possibility to crystalline the amorphous. Crystalline samples modified for 20min reveal partial surface amorphization (Fig. 9b–d), which later converts into a completely amorphous microporous silicon structure.
A detailed study of Rivas et al. [51] correlates Si erosion to its crystalline structure in an ultrasonic device employing micropits [52]. Together with controlling the ultrasonic reactor parameters (Table 1), an ultrasound device enables the control of the location and amount of cavitation bubbles and the surface modification effects on a millimeter scale [6,51,52]. It was observed [51] that the concerted effect of various sources of damage formation such as jetting, shock waves, direct bubble impact, and surface stress corrosion can all cause the damage observed for the three crystallographic silicon surfaces studied, although each of the three surfaces has a different resistance to erosion. For (100) silicon, and under the current working conditions, the incubation time was of the order of 50min, whereas for (110) and (111) apparently the incubation period is larger than the total 180min sonication.
Spectroscopic investigations reveal [50] (Fig. 3) that argon (bubbling continuously through the liquid phase during experiments) can be ultrasonically excited via mechanoluminescence, i.e., emission of light caused by mechanical action on a solid. This phenomenon is highlighted being important and showing that material from the solid surface can affect the bubbles.
Here it is worth to discuss the advantage of in-situ analysis to monitor ultrasonic treatment. A simple possible set up for in situ monitoring is presented in Figs. 1 and 3. The in situ control allows to follow the kinetics, which, in most cases, is nonlinear. It enables to directly measure the formed surface structure and its development with time.

The ultrasound assisted modification of silicon plates in the

The ultrasound-assisted modification of silicon plates, in the form of both crystalline silicon wafers and amorphous silicon deposited onto glass, were studied [12]. In general, the interaction of cavitation bubbles with the silicon surface results in mechanical and chemical modification. As was already mentioned (see Table 1), the ultrasonic modification of solids is known to be controlled by various sonication conditions, including the intensity and duration of sonication, the solvent, and the concentration and size of the sonicated species, oxidants, and reducing agents involved. The important innovation we introduce in our work [12] is the addition of hydrogen donors, such as in aqueous solutions magnesium particles or sodium borohydride, during ultrasonication, which has a dramatic influence on the process. The sonication of silicon species in water (Fig. 9), that does not contain a hydrogen donor, results in the formation of an oxidized surface caused by the 4-aminopyridine of the silicon by-products of water sonolysis. The samples are characterized by a slight increase in their surface roughness and the absence of photoluminescence. The hydrogen donors slow down the surface oxidation processes, which are brought in by free radicals formed during water sonolysis, and stabilize the porous structure through the formation of silicon-terminated bonds. In this case, Si–H bonds could be formed as an alternative to, or together with, Si–O bonds. The illustration in Fig. 9a, based on a 3D reconstruction of TEM and μ-confocal measurements of the surface after high-intensity ultrasonic exposure, shows our general concept of a single-step “green” method for the construction of surfaces with different porosities. Without a reducing agent present during modification in water, neither porous nor luminescent structures were observed. However, in the presence of a reducing agent, luminescent structures with a range of porosities (25–40% in water, 60–70% in water/alcohol mixtures, and 40–50% in an ionic liquid) were detected. Furthermore, the differences in porosities correlate with differences in photoluminescence (green or red).
Moreover it was shown [12,50] that ultrasonic treatment (20kHz, 57W/cm2) affects the surface crystal structure (Fig. 9b–d, 4-aminopyridine insets): (i) provides amorphization of crystalline structures; and (ii) alternatively possibility to crystalline the amorphous. Crystalline samples modified for 20min reveal partial surface amorphization (Fig. 9b–d), which later converts into a completely amorphous microporous silicon structure.
A detailed study of Rivas et al. [51] correlates Si erosion to its crystalline structure in an ultrasonic device employing micropits [52]. Together with controlling the ultrasonic reactor parameters (Table 1), an ultrasound device enables the control of the location and amount of cavitation bubbles and the surface modification effects on a millimeter scale [6,51,52]. It was observed [51] that the concerted effect of various sources of damage formation such as jetting, shock waves, direct bubble impact, and surface stress corrosion can all cause the damage observed for the three crystallographic silicon surfaces studied, although each of the three surfaces has a different resistance to erosion. For (100) silicon, and under the current working conditions, the incubation time was of the order of 50min, whereas for (110) and (111) apparently the incubation period is larger than the total 180min sonication.
Spectroscopic investigations reveal [50] (Fig. 3) that argon (bubbling continuously through the liquid phase during experiments) can be ultrasonically excited via mechanoluminescence, i.e., emission of light caused by mechanical action on a solid. This phenomenon is highlighted being important and showing that material from the solid surface can affect the bubbles.
Here it is worth to discuss the advantage of in-situ analysis to monitor ultrasonic treatment. A simple possible set up for in situ monitoring is presented in Figs. 1 and 3. The in situ control allows to follow the kinetics, which, in most cases, is nonlinear. It enables to directly measure the formed surface structure and its development with time.

purchase Sitagliptin phosphate monohydrate In the last years as a intensify method

In the last years as a intensify method of heterophase processes, ultrasonic processing presents great interest to researchers [22–24]. Acoustic waves are known to cause the following effects in liquids [25]: (1) activation of mass transport; (2) heating; (3) cavitation, i.e., generation of bubbles, which then collapse, giving rise to high local temperatures and pressures. It is reasonable to expect that the synthesis of oxide will also involve effects peculiar to sonochemical processes [24–27]: (1) formation of additional nucleation centers in the vicinity of bubbles; (2) increased growth rate of the particles of the new phase owing to accelerated mass transport; (3) disintegration of purchase Sitagliptin phosphate monohydrate and agglomerates of primary crystallites by the shock waves resulting from bubble collapse.
Some studies make an attempt to explain the effect of ultrasound on the properties of crystals, but the basic mechanism of synthesis and crystallization under ultrasonic waves is not yet known. Four hypotheses have been proposed:
In Ref. [31], a review of the effects of ultrasound on the synthesis of zeolites has been presented. It was shown that ultrasonic treatment allows essentially reducing the time of crystallization of various types zeolites from solutions, gels and sols. Researches on the use of ultrasound for the synthesis of low-modulus zeolites are also well known [32–34]. As a raw material, aluminum hydroxide and silica of different origin had been used. The authors of these studies found that treating a suspension with ultrasound allows to reduce crystallization time and duration of aging the reaction mixtures as well as to increase the crystallinity degree of zeolites.
By these methods, zeolites can be obtained only as a powder. For industrial applications of these zeolites, it is necessary to use a binder (e.g., clay), which reduces the effectiveness of zeolites. At the present time, in industry the LTA zeolites are prepared using the zeolitization of metakaolin in solutions of sodium hydroxide and sodium aluminate [11,35]. In this case, the granulated zeolite can be obtained without the use of binders. The disadvantages of this method are the long duration of the process and the formation of large amounts of spent crystallization solution, as well as the insufficiently high degree of the zeolite crystalline.
For granulated zeolite synthesis, notochord has been proposed a method which comprises pretreating the metakaolin mixture and other ingredients, the thermal treatment and the hydrothermal crystallization [36]. The thermal treatment is required to obtain the strength pellets. Simultaneously with increase in the strength during calcination, the solid-phase reactions occurs Sodalite, nepheline, quartz and other crystalline phases can be formed as a result of these reactions. It has been shown [18,19] that in order to control the solid-phase thermal synthesis, the presence of sodium aluminate cubic syngony is necessary. These substances should be synthesized at the pretreatment stage.

Experimental procedure

Results

Discussion
The formation of sodium aluminate purchase Sitagliptin phosphate monohydrate of cubic syngony (Reaction (II)) are important result of suspension USP. It is possible to assume the following mechanism for the process. Under the action ultrasound, the cavities (bubbles) appear in the liquid phase [22]. Since the process is cyclic (expansion gives way to contraction), the collapse of cavities occurs. Collapse generates the shock waves which reduce the thickness of the laminar boundary layer. Under the action of a shock wave, a local increase in temperature is possible also [25]. These phenomena allow to increase the aluminum oxide solubility in alkali. After removal of water, sodium aluminate is crystallized.
The destruction and deformation of SiO and AlO bonds in the structure of metakaolin is another effect of ultrasound. This is confirmed by large broadening and a small intensity of the band at 1300–900cm−1 (Fig. 8a). The destruction and deformation of Si(Al)O bonds we also attribute to the action of the shock wave that arises after the bubbles collapse. These processes allow changing the course of further heterophase synthesis at later stages.

Particle distribution of the reagent powders in the fabrication process

Particle distribution of the reagent powders in the fabrication process can be controlled to obtain homogeneous ceramics with a small dielectric loss, which is very crucial for many applications. Ultrasonication or conventional milling methods can be used in the homogenization process. The processes not only homogenize the powders but also decrease the particle size of the powders and activate them [31,16,27,17,24,1,2]. Mechanical milling of the powder is one of the common methods for the homogenization process. In the conventional mechanical milling process, the powders in the shaker are subjected to high-energy collisions from the balls. But it order ryanodine is difficult to obtain a homogeneous mixture with the uniform particles of the powder; that effect appeared clearly after sintering as different grain walls [12]. The particle size of the powder can be controlled by the ultrasonic method, which is based on the acoustic cavitation phenomenon. High-intensity ultrasonic waves generate, enlarge and collapse a lot of bubbles in the liquid [6,7]. Collapsing bubbles produce micro/nano dots with local high temperatures and intense pressure. High temperatures and intense pressure deagglomerate the grains of the powder. Recently, micro/nano-materials have been successfully prepared by the ultrasonic method, including BaCO3[3], CuInS2[25], SiC [21], Mg(OH)2 and MgO [4].
In this study, new ultrasonication and conventional mechanical milling methods used for the homogenization of reagent powders to obtain pure and Nb-doped BaTiO3 ceramics in the solid-state reaction process. We have compared two methods to discover to homogenization and deagglomeration effects on structural and dielectric properties of pure and Nb-doped BaTiO3 ceramics.

Experimental procedure
BaCO3, TiO2, and Nb2O5were purchased from Alfa Aesar (UK) and were used as analytical grades (>99.5%). BaTiO3-based ceramics with Nb additives (%0.0, and% 1.0 w) were prepared using the solid-state reaction method. The powders were homogenized by two methods:
After homogenization, the powder mixtures were dried in a drying oven at 120°C for 1h. The obtained powders were calcined at 1100°C for 4h in alumina crucibles. Table 1 shows the experimental conditions. The structures of the powders were confirmed by Fourier transform infrared spectroscopy (FTIR) (Shimadzu, IRAffinity-1S, Japan) and X-ray diffraction (XRD) with (Rigaku, Smart Lab, Japan) diffractometer. FTIR analysis was performed in the range of 400–4000cm−1 with a signal-to-noise (S/N) ratio of 30,000:1 (the peak-to-peak resolution is 0.5cm−1 at the neighborhood of 2100cm−1). XRD analysis was obtained in the range of 10°⩽2θ⩽90° with CuKα radiation. The surface morphologies of the powders were analyzed using Scanning Electron Microscopy (SEM) (JEOL, 5500, Japan). The calcined powders were pressed into pellets that were approximately 10mm in diameter and 2mm thick by a computer-controlled press. The pellets were sintered at 1300°C for 2h to achieve dense ceramic pellets. SEM images were used to analyze the morphologies of the sintered pellets. Complex impedance measurements of the samples were carried out using an Agilent E4980A LCR meter at oscillation amplitude of 1V. Complex permittivity (, ) and complex AC conductivity (σ′ and σ″) were analyzed in a wide frequency range of 20Hz to 2MHz at room temperature.

Results

Discussion
An ultrasonic processor with high-intensity ultrasonic waves based on the acoustic cavitation phenomenon or the conventional mechanical milling method with zirconia balls could be used to homogenize and deagglomerate the powders in the first step of the solid-state processes. These processes have also activated the powders and improved the structure and dielectric properties of the ceramics [16,31,27,17,24]. The homogenization process’ effects on the structures and dielectric properties of undoped and Nb-doped BaTiO3 ceramics prepared using the ultrasonic method and the conventional mechanical milling method have been investigated.

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 Nocodazole 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 Nocodazole 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 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 Experimental procedure br Results br Discussion br Conclusions

Experimental procedure

Results

Discussion

Conclusions
Joining of bare alumina ceramic/Cu was carried out in air through an ultrasonic-assisted brazing method by using a Zn-14Al filler metal for a serial UVDT. The effects of the UVDT on the microstructures and mechanical properties of the joints were systematically investigated. The conclusions were summarized as follows:

Introduction
One of the major concerns in the developing countries is the presence of organic dyes in wastewater of several industries such as textile, paper, leather and food processing. The organic dyes cause serious problems for human health and other living organisms because of their toxic and carcinogenic effects [1,2]. In light of this, elimination of industrial organic dyes from wastewater has gained great attention. The treatment of polluted wastewater containing organic dyes can be performed with different physicochemical and biological methods including adsorption, chemical oxidation, membrane technology and advanced oxidation processes (AOPs) [3–5]. Adsorption is one of the most effective treatment processes due to its simplicity and low cost [6]. Various materials have been used for dye removal from wastewater via adsorption. Recently, carbon based adsorbents have been frequently used in water purification due to their abundance and low cost [7]. Hydrochar is a carbon-based adsorbent prepared through hydrothermal carbonization of SAG supplier wastes, such as spent coffee grounds or rice husk [8,9]. However, it is difficult to separate the used carbon-based adsorbents from treated wastewater. For this, Fe3O4-loaded adsorbents have attracted great attention due to their unique properties such as easy recovery through a magnet, large surface area, simple manipulation process and high separation efficiency [10–12].
Another technique to enhance the efficiency of adsorption technique is the combination with other treatment processes [6,13]. Ultrasounds have been used frequently in direct degradation of organic pollutants or in combination with catalysts or adsorbents in ultrasound-assisted processes [14,15]. The improved removal efficiency of pollutants in ultrasound-assisted processes can be explained through the following mechanisms: (i) Direct sonolysis of pollutants: high intensity ultrasonic waves in liquid phase produce bubbles in liquid medium by cavitation phenomena. Collapsing of these bubbles generates localized high temperature and pressure, which in turn convert H2O molecules to OH and H radicals. The produced OH radicals attack and degrade the organic pollutants [16,17]. (ii) Sonocatalysis: the presence of suitable particles can enhance the oxidation efficiency of the system by generating more nucleation sites for cavitation phenomena [17,18]. (iii) Ultrasound-assisted enhanced adsorption: the resulted energy from ultrasonic irradiation enhances the mass transfer efficiency through convection pathway and also activates the surfaces sites of aggregated particles [6,7]. Furthermore, it has been proven that ultrasonic irradiation can be used as a very effective technique in increasing the adsorption of dyes on adsorbent by enhancing the affinity between adsorbent and adsorbate.
In this study, Fe3O4-loaded coffee waste hydrochar (Fe3O4-CHC) was synthesized through a simple precipitation method. The synthesized adsorbent was characterized by SEM, TEM, EDX, XRD, BET and FT-IR analysis. The ultrasound-assisted process in the presence of Fe3O4-CHC was used to remove AR17 dye from aqueous solution. The effects of adsorbent dosage, initial dye concentration, presence of inorganic anions and ultrasonic power on the dye removal efficiency were investigated. The Langmuir and Freundlich isotherms were used to justify the experimental data. The produced intermediates of degradation of AR17 were also identified by GC–MS analysis.

Materials and methods

Results and discussion

Conclusions
The Fe3O4-loaded coffee waste hydrochar (Fe3O4-CHC) was synthesized using a simple precipitation method. The results of SEM, TEM, EDAX, XRD, BET and FT-IR analysis confirmed the formation of Fe3O4 nanoparticles on the surface of the hydrochar. The results of BET analysis showed that the specific surface area increased from 17.2 to 34.7m2/g after loading Fe3O4 onto the bare hydrochar. The synthesized Fe3O4-CHC was used for removal of AR17 anionic dye through ultrasound-assisted adsorption process. An increase in Fe3O4-CHC dosage up to 2g/L led to the enhancement in the removal efficiency of AR17. With increasing initial dye concentration, the removal efficiency decreased from 100 to 74%. The presence of Cl− and SO42− ions retarded the removal of AR17. The results of the reusability tests showed that Fe3O4-CHC adsorbent can be used effectively for several runs for organic pollutants removal. The high correlation coefficient (R2=0.997) obtained from the Langmuir model indicated that physical and monolayer adsorption of dye molecules occurred on the Fe3O4-CHC surface.

A number of analytical techniques are available for evaluating particle

A number of analytical techniques are available for evaluating particle size of a suspension, in addition to N-(p-amylcinnamoyl) microscopy; such as DLS, centrifugal liquid sedimentation, and small-angle X-ray scattering, to name a few [36]. In this study, particle size distribution of nanofluid samples was attained by DLS measurements with a zetasizer. Although, the size distribution of nanoparticles is mostly referred to as particle size distribution, in reality, aggregation of particles is mostly significant in a dispersion. In that case, one may talk about cluster of particles, rather than individual particles. Fig. 5 presents an idea about the clustering mechanism. In that case, the effective diameter is not the diameter of a single particle. Rather, it is the diameter of a group of aggregated particles.
Consideration of Fig. 5 with FESEM and TEM images given in this study (and in the literature) together is required in order to understand the effective diameter for a particular mixture, and geometrical structure of aggregates. Results for the average cluster sizes with respect to different ultrasonication durations are presented in Fig. 6, together with literature data collected for different ultrasonication durations. It could be noted that the primary nanoparticle diameter was around 21nm, according to the information provided by the manufacturer. Here in Fig. 6, the cluster sizes collected in this study were within the range of 167–315nm after different ultrasonication durations, which was greater than the average size of a single nanoparticle.
Results presented in Fig. 6 are indicative of decrease of mean cluster sizes with ascending ultrasonication period. When the data of the present study is examined, it can be seen that the use of intense ultrasonic energy resulted in a more than two times decrease in cluster size, by breaking down the nanoparticle aggregates. While appreciable decrease of cluster sizes for ultrasonication durations up to 150min can be seen in Fig. 6, no significant improvements were observed in particle size decrease with longer ultrasonication durations (i.e., 180min). It is also observed in Fig. 6 that cluster sizes sharply decreased right after the application of ultrasound energy. The tendency of the decrease in cluster size was greater in the beginning, in comparison to the latter parts of ultrasonication period. The results of the present study is also compared with the data of Sadeghi et al. [11] and Mahbubul et al. [28], in Fig. 6. The data of Sadeghi et al. [11] and Mahbubul et al. [28] had similar decreasing trends in cluster size rate with ultrasonication as reported in MTOC study. During the first 30min of ultrasonic treatment, the rate of decrease in average cluster size was the highest for the data in [11], compared to the data of present study, and those of [28]; in comparison to the latter parts of the ultrasonication period. The average cluster size data obtained in [11] were higher than those of the present study. The reason behind this outcome is most probably due to the fact that the primary nanoparticle size in [11] was 25nm, and nanoparticles might initially have high level of agglomeration. Their achievable minimum cluster size was about 158nm after 180min of ultrasonication for Al2O3–H2O nanofluid. The data reported in [28] were the lowest compared to the data of the present study and those in [11]. Mahbubul et al. [28] reported 110nm of cluster size after 180min of ultrasonication, while the primary nanoparticle size of their samples was 13nm. Chen et al. [18] found a lowest aggregate size of ∼140nm for TiO2 nanoparticles, after 20h of ultrasonication, where the primary particle size was 25nm. Therefore, aggregate size depends more on initial primary size than the sonication power [37]. Also, the differences in the decreasing rates can be attributed to the effect of the nanoparticle (or cluster) material types, which may affect the tendency of the primary nanoparticles to form agglomerates, and break down to a mono-dispersed condition if previously agglomerated.