kHz Frequency Research Articles

Acoustic Target Strength of Jellyfish, Nemopilema nomurai, Measured at Multi-Frequency and Multi-Orientation

The jellyfish Nemopilema nomurai occupies an important position in the Northwest Pacific ecosystem, and monitoring its biomass is necessary to ensure the protection of fishery resources and the safety of offshore industrial production. The acoustic method has been proposed for jellyfish flux estimation and bloom warning, in which the target strength (TS) of the jellyfish is a crucial parameter. However, varied swimming orientations of jellyfish aggregation result in different backscatter strengths. The acoustic echo characteristics in horizontal swimming orientations and multi-frequency broadband signals are yet to be revealed. This study aims to obtain the TS of jellyfish in various orientations and to comprehensively investigate the jellyfish acoustic echo features at various frequency broadband sounds. In an anechoic tank, we used wide-band echosounder and 70 kHz, 120 kHz, and 200 kHz split-beam transducers to measure the TS of jellyfish swimming omnidirectionally. The results show a difference of approximately 4 dB in the jellyfish’s normalized TS at 70 kHz (frequency range: 45 kHz to 95 kHz) and 200 kHz (frequency range: 160 kHz to 260 kHz) center frequency. The normalized TS of jellyfish varies by around 8 dB between horizontal and vertical swimming orientations. For jellyfish swimming horizontally, the TS and bell diameter have the following least squares fits: T S D 70 k H z = 20 log D − 89.36 r 2 = 0.83 ; T S D 200 k H z = 20 log D − 93.85 r 2 = 0.83 . The swimming orientation has significant effects on TS estimation and model construction.

Impact of different processing techniques (chemical, heating and sonication) on physicochemical and microbial characterization of kinnow-whey based beverage

Whey beverages that have been added with fruits pulp have always been remained the priority demand of food consumers, but loss of nutritional contents and microbial safety of such beverages is always matter of concern of food producers. To overcome these issues food experts are always in try to find out the processing and preservation techniques for safety of these beverages. In present study kinnow-whey beverage was prepared by addition of kinnow concentrate and acidic whey, at optimum concentrations. Effect of different processing techniques on the physicochemical properties, microbial inactivation, and sensory characteristics of beverage were investigated during 90 days of storage. The outcomes of pasteurization were compared with non-thermal techniques, such as use of preservatives and sonication (20 kHz frequency, 70% amplitude and 5, 10 and 15 min). pH values of all the treatments were reduced, whereas titratable acidity was increased significantly, during storage. There was a significant increase in the brix, viscosity and total solids, with the increase in the storage period. Highest values obtained for brix, viscosity and total solids were T3 (14.32°), T3 (15.13 cP), and T3 (15.13 mg/L) after 90 days storage, respectively. Total plate count (TPC) and yeast and mold count were increased during prolong storage in all treatments. Results showed that the maximum TPC was noted in T0 (2.9 × 104 cfu/ml) at 90 days, while minimum TPC was observed in T5 (0.8 × 104 cfu/ml) at start of study. Similarly, maximum yeast and mold count were noted in T1 (3.2 × 104 cfu/ml) at 90 days whereas, minimum yeast and mold count was observed in T5 (0.1 × 104 cfu/ml) at start of study. Overall acceptability of beverage was highest in 15 min sonicated treatments. It was concluded that the beverages processed with sonication (15 min) demonstrated better stability and sensory attributes compared to other techniques.

Sonoluminescence Spectroscopy for the Analysis of Natural Brine

The use of ultrasound (us) for the determination of main component (NaCl) and main admixtures (CaCl2, MgCl2) of natural brine was investigated. The NaCl content was determined using us of ultrahigh frequency (10 to 25 MHz with the optimum at 20–22 MHz) and of 20 W·cm−2 intensity. The admixture concentrations were determined with the simultaneous application of us of ultrahigh (10–25 MHz) and low (18–23 kHz) frequencies at intensities of 20 and 1.3–1.5 W·cm−2, respectively. This approach reduced the lower determination boundary down to 0.1 g·dm−3, i.e., by a factor of 5. An analytical routine of complex determination of sodium chloride and macroimpurities content in brines of different origin was developed using sonoluminescence spectroscopy.

Application of acoustic levitation for studying convective heat and mass transfer during droplet evaporation

The observation of acoustically levitated droplets offers great potential for studying their evaporation characteristics under well-defined ambient conditions. In contrast to alternatives such as sessile droplets or droplets suspended by a tiny fiber, the key advantage of acoustic levitation is the contact-free nature of the experimental method. However, acoustic streaming effects or droplet deformation by acoustic forces may affect the heat and mass transfer considerably. Consequently, the droplet evaporation process is usually dominated by these intrusive effects of the acoustic field. The main objective of this study is to present an experimental setup, which minimizes the disturbing effects of the levitation technique in order to enable a solid investigation of convective heat and mass transfer during droplet evaporation. To achieve this goal, a high resonance frequency of 100kHz is chosen and the investigation is limited to substantially smaller droplets compared to other studies in the literature. Moreover, an air flow is injected through a hole pattern in the reflector in order to control the relative velocity between the droplet and the gas phase. Particle Shadow Velocimetry is used to characterize the gas flow field in a stepwise approach, initially without any levitated droplet. Subsequently, the vortex structures around non-evaporating droplets are discussed. Eventually, evaporating water droplets are studied. The applied optical diagnostics offer the distinct advantage that the droplet size can be measured simultaneously with the surrounding gas flow field. Hence, the evaporation rate can be evaluated for different combinations of droplet size and relative velocity to the gas phase. For the entire range of resulting Reynolds numbers, the experimentally obtained evaporation rates were found to agree very well with results of a numerical evaporation model when a well-established correlation is used to account for convective heat and mass transfer.

Therapeutic Ultrasound for Enhanced Corneal Permeability to Macromolecules.

Topically applied macromolecules have the potential to provide vision-saving treatments for many of the leading causes of blindness in the United States. The aim of this study was to determine if ultrasound can be applied to increase transcorneal drug delivery of macromolecules without dangerously overheating surrounding ocular tissues. Dissected corneas of adult rabbits were placed in a diffusion cell between a donor compartment filled with a solution of macromolecules (40, 70 kDa, or 150 kDa) and a receiver compartment. Each cornea was exposed to the drug solution for 60 minutes, with the experimental group receiving 5 minutes of continuous ultrasound or 10 minutes of pulsed ultrasound at a 50% duty cycle (pulse repetition frequency of 500 ms on, 500 ms off) at the beginning of treatment. Unfocused circular ultrasound transducers were operated at 0.5 to 1 W/cm2 intensity and at 600 kHz frequency. The greatest increase in transcorneal drug delivery seen was 1.2 times (P < .05) with the application of pulsed ultrasound at 0.5 W/cm2 and 600 kHz for 10 minutes with 40 kDa macromolecules. Histological analysis revealed structural damage mostly in the corneal epithelium, with most damage occurring at the epithelial surface. This study suggests that ultrasound may be used for enhancing transcorneal delivery of macromolecules of lower molecular weights. Further research is needed on the long-term effects of ultrasound parameters used in this study on human ocular tissues.

Impact of Micropulse and Radio Frequency Coupling in an Atmospheric Pressure Plasma Jet on the Synthesis of Gold Nanoparticles

Gold nanoparticles have been extensively studied due to their unique optical and electronic properties which make them attractive for a wide range of applications in biomedicine, electronics, and catalysis. Over the past decade, atmospheric pressure plasma jets in contact with a liquid have emerged as a sustainable and environmentally friendly approach for synthesizing stable and precisely controlled dispersions. Within the context of plasma jet/liquid configurations, researchers have explored various power sources, ranging from kHz frequencies to nanopulse regimes. In this study, we investigated the effects of coupling two distinct power supplies: a high-voltage micropulse and a radio frequency (RF) generator. The variations within the plasma induced by this coupling were explored by optical and electrical measurements. Our findings indicated a transition from a bullet plasma propagation mechanism to a capacitive coupling mechanism upon the introduction of RF energy. The impact on the production of metal nanoparticles was also examined as a function of the radio frequency power and of two distinct process gases, namely helium and argon. The characterization of gold nanoparticles included UV-visible spectroscopy, dynamic light scattering, and scanning electron microscopy. The results showed that the size distribution depended on the type of process gas used and on the power supplies coupling. In particular, the incorporation of RF power alongside the micropulse led to a decrease in both average particle size and distribution width. The comparison of the different set up suggested that the current density can influence the particle size distribution, highlighting the potential advantages of the use of a dual-frequency atmospheric pressure plasma jet configuration.

Computing the stress intensity factor range for fatigue crack growth testing at 20 kHz

AbstractInertia and damping influence the values of the stress intensity factors (SIFs) at high‐frequency loading and they must be included in computations. In the present study, different dynamic simulation procedures were carried out for two types of specimen geometries and the achieved SIF values were compared. Fast computation procedures such as harmonic modal analysis and direct steady‐state analysis were compared to the computationally expensive transient dynamic analysis. Two different methods for calculating the SIF, the J‐integral and the crack tip opening displacement (CTOD) methods, were applied and compared and the results showed a near perfect agreement in calculation of the mode I SIF. The Rayleigh damping model was introduced into the dynamic computation to investigate its effect and the results revealed a clear effect on the SIF at 20 kHz frequency. The fast direct steady‐state analysis showed good agreement to both harmonic modal and transient analysis with the different damping values used and is, after this study, the recommended procedure.

High-frequency plasma spark discharge assessment in pulse-scanning digital holographic interferometry.

In this paper, we consider the method for observing and detecting of high-frequency pulsed plasma spark discharge by means of stroboscopic digital holographic interferometry to demonstrate the feasibility of the electron concentration assessment in nonthermal plasma. A spark discharge with a 5kHz frequency and 1250ns duration has been exited between two electrodes in atmospheric pressure. The sequence of holograms acquired due to the proper synchronization between plasma pulses, laser radiation, and the camera's frame grabbing that ensure the recording of the plasma pulses at different moments of time, and the temporal optical scanning of plasma pulse were realized. We also show that the phase difference contrast variation corresponds to the plasma's instant and indicates a change in the electron concentration in the discharge. The concentration of electrons at different moments of plasma existence has been estimated. The limitations of the proposed method are considered, and its applicability for the study of low-temperature pulsed plasma are discussed.

Optimization of thermosonication treatments to improve the quality parameters of posotia (Vitex negundo) juice

In the current study, the influence of heat and thermosonication on the physico-chemical (cloudiness value, ascorbic acid content, pH, total soluble solid (TSS), titratable acidity (TA), and browning index (BI)), functional (total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (AA)) and microbial (total plate count and yeast and mold count (YMC) characteristics of juice derived from leaves of posotia (Vitex negundo) was studied. Juices were thermosonicated using two different frequencies, namely 33 and 44 kHz with various time periods of 30, 45, and 60 min while maintaining treatment temperatures at 30, 40 and 50 °C. Treatment with heat and thermosonication (TS) did not result in any appreciable changes to pH, TSS, or TA. Increases in AA, TPC, TFC, cloud value, and browning index were seen after TS. However, the ascorbic acid level of posotia leaf juice was decreased after TS. The TPC, TFC, and antioxidant activity of the posotia leaf juice samples processed at 50 °C with 44 kHz frequency for 60 min, were found to be higher as compared with other TS conditions. The microbial populations in posotia juices were also significantly reduced by TS treatments. Microbes in juice samples were completely inactivated by thermal treatment, however there was also a noticeable reduction in quality indices. The findings of the study suggested that juices might be processed with TS without affecting the quality characteristics of posotia juices.

Experimental and numerical investigations of induction heating for Ti-6Al-4V sheets and epoxy/carbon fiber composite laminates

The objective of this study is to present the electromagnetic and the thermal multi-field coupling model of the induction heating process for numerical simulation based on the finite element method. One of the most important difficulties encountered in the induction heating processes is to ensure homogeneous temperature distribution throughout the part. To improve the uniform temperature distribution in the sheet, the induction heating system is modelled with the ANSYS software taking into account some operational and geometrical parameters including current density and coupling distance between induction coil and sheet. Induction heating simulations were performed for all simulations at 20 kHz frequency ANSYS Maxwell. The numerical model has been verified by the conducted experiments for Ti6Al4V at the current of 50 A, 125 A, and 200 A, and the 1 mm and 3 mm gap distances. The relative error of the maximum temperature between the experiment and simulation was found around 14 % recorded at 25 s measurements. In addition, the effects of the current and the frequencies on the induction heating were evaluated by the verified numerical model for epoxy/carbon fiber (UD prepreg) and epoxy/carbon fiber (Woven prepreg) plates. The results show that the induction heating model is suitable and efficient to determine the temperature distribution within the thin plates by the finite element method.

The phase shift of the envelope-following response as an indicator of the traveling wave propagation in the beluga cochlea

Auditory system of the toothed whales features a number of modifications that allow to adapt to aquatic life and echolocation. One of unanswered questions is how the characteristics of the traveling wave changed due to extension of frequency range. We hypothesize that the phase shift of the envelope-following response (EFR) reflects the traveling wave propagation along the basilar membrane in the cochlea. EFRs were non-invasively recorded in the beluga whale. The sound stimuli were tone burst of carrier frequencies of 16 to 128 kHz and envelope frequency of 1 kHz. Thus, all EFR contained the fluctuations with 1 kHz frequency. The EFR phase shift depended on the carrier frequency and the sound intensity: the higher intensity and frequency, the greater the phase shift. If it is accepted that at the EFR threshold the phase depends only on the carrier frequency, the phase shift allows to calculate the time of the traveling wave propagation along the basilar membrane. The travelling wave time between the regions corresponding to 16 and 128 kHz was approximately 0.8 ms.

Blind-label acoustic subwavelength imaging

There is a long-existing tradeoff between the imaging resolution and the penetration depth in acoustic imaging caused by the diffraction limit. Most of the existing subwavelength imaging approaches that address this trade-off require exogenous “labels,” such as metamaterials or contrast agents, to be deposited close to the objects. Those labels need to either remain static or be tracked precisely during imaging, therefore, are extremely restrictive in practical applications. This talk will present our recent work on a “blind label” approach for acoustic subwavelength imaging. The “blind labels” are randomly distributed acoustic scatterers with deep-subwavelength sizes whose exact locations and trajectories are unknown. A hardware/software co-design framework is developed that is composed of two parts: 1) spatial mixing: a physical process that converts the originally evanescent components in the scattered waves from the object to propagating components that can reach the far-field detector; 2) computational image reconstruction. Our experiments both in air at KHz frequency range and in water at MHz frequency range achieved multi-fold resolution enhancement. The proposed “blind-label” approach relaxes the restrictions of depositing controlled labels close to the object, therefore significantly improving the practicality of acoustic subwavelength imaging in acoustic sensing, imaging, and communication applications.

Evaluation of sound localization and speech recognition with a sound enhancing connection tube for non-linear earplugs

Noise-induced hearing-loss (NIHL) can occur when an individual is exposed to high-intensity acoustic stimuli. To prevent NIHL, individuals may use non-linear-earplugs (NLEPs) that provide some attenuation, substantially within the frequency range of 1–4 kHz. Wearing NLEPs can reduce speech recognition as well as sound localization. As weapon noise is mostly present in the 1–4 kHz range and is therefore partly attenuated by NLEPs, there is a downside to the reduced ability of a soldier using them to localize the source of enemy gunfire. A perforated sound-enhancing connection tube (SECT) was designed to connect to NLEPs for improving the user’s ability to localize sound and speech recognition in noise while retaining the NLEPs's noise attenuation benefits of protecting one's hearing. A previous experiment examined the effect of the SECT with NLEPs on the Head Related Transfer Function (HRTF) of a head-and-torso-simulator (HATS) (manikin). The obtained HRTF demonstrated a 3–10 dB difference in the 1–4 kHz frequency range relative to the HRTF with the NLEPs alone, implying that sound stimuli in that frequency range might be more audible to the user. The presented work will demonstrate the speech recognition in noise and sound localization of participants when using the SECT with NLEPs.

Toward ultrasound-mediated elasticity modulation and monitoring in the crystalline lens

Presbyopia is the age-related stiffening of the crystalline lens, reducing near vision. We propose ultrasonic cavitation to interact with the lens structure and restore flexibility by disrupting the disulfide bonds responsible for lens stiffening. Peak negative pressure of 25MPa for 6-μs pulses at 2 MHz with a 100 Hz pulse repetition frequency allowed cavitation nucleation in the lens nucleus of both 6-months and 3-years old porcine eyes. Disulfide bonds disruption was evaluated in both ovoalbumin gels and ex vivo lens using Raman spectroscopy. We explored the measurement of surface wave dispersion over a 0.1 to 2 kHz frequency range to evaluate viscoelastic properties of the lens samples. We identified two regions in the dispersion curves: a sharp decline at low frequency due to guided waves and a gradual slope at high frequency, attributed to viscoelastic dispersion of a Scholte wave. By fitting the dispersion curves with a Kelvin–Voigt model, we found that while the impact of ultrasound remained uncertain, elastography allowed appreciating the age-dependentshear and viscosity moduli.

Electrical and dielectric properties of EVA/modified lead titanate elastomer composites

At first, the modified lead titanate (PWNTO) was synthesised by cost-effective solid-state reaction method.The ethylene–vinyl acetate (EVA)/PWNTO polymer composites with 2.5, 5.0, 7.5 and 10.0 wt% of PWNTO were fabricated by the solution casting method. The present communication highlights the dielectric behaviour, ac conductivity, impedance of these elastomer composite-sheets. As the inorganic filler content increases in the elastomer-system of EVA/PWNTO, the relative dielectric constant increases. The ac-conductivity of the above films also increasing in the frequency 1kHz to 1 MHz. The behaviour of the Nyquist-plot is simulated with an equivalent circuit of (CQR)(CR); from this the parameters like the bulk capacitance (Cb), bulk resistance (Rb) and frequency factor(n) were evaluated.

Investigation on tailoring the width and central frequency of bandgaps of TPMS structures

AbstractTriply periodic minimal surfaces (TPMS) lattice structures present outstanding properties such as lightweight, high strength, energy absorption, and wave propagation control, which are extensively investigated in recent years. However, one of the main challenges when designing TPMS is the proper selection of cell type and volume ratio in order to obtain the desired properties for specific applications. To this aim, this work provides a comprehensive numerical study of bandgap’s formation in the sub-2 kHz frequency range for the seven major cell type TPMS structures, including Primitive, Gyroid, Neovius, IWP, Diamond, Fischer–Koch S, and FRD, for a comprehensive range of volume ratios. Results show that these seven TPMS structures present a complete bandgap between the 3rd and 4th dispersion curves. The width of the bandgap is strongly dependent of the TPMS lattice and the widest bandgaps are seen on the Neovius and Primitive-based lattice (reaching a maximum width of 0.458 kHz and 0.483 kHz, respectively) for volume ratios over 0.3. Below this volume ratio, the bandgap of the Primitive structure becomes negligible, and the Neovius and IWP structures are the best candidates among the 7 tested TPMS cases. The central frequency of the bandgaps is less sensitive to the lattice and are predominantly tailored by the volume ratio. With this study, we demonstrate that the proper selection of the periodic cell type and volume ratio can tailor the bandwidth of complete bandgaps from a tens of Hz up to 0.48 kHz, while the central frequency can be selected from 0.72 to 1.81 kHz according to the volume ratio. The goal of this study is to serve as a database for the Primitive, Gyroid, Neovius, IWP, Diamond, Fischer–Koch S, and FRD TPMS structures for metamaterial designers.

Laser textured Ti-6Al-7Nb alloy for biomedical applications: An investigation of texturing parameters on surface properties.

Surface texturing with a laser beam is an effective method for engraving on the surface of biomaterials. The four laser texturing parameters (scan speed, frequency, fill spacing, and pulse width) having five different values were associated with five different scanning strategies (scan direction), and a total of 25 texturing conditions were tested on the Ti-6Al-7Nb alloy surface. The surface roughness and wettability of the textures created with a 20 W nanosecond fiber laser with a wavelength of 1064 nm on the surface of Ti-6Al-7Nb biocompatible alloy were investigated. Laser texturing parameters were analyzed according to the lowest surface roughness and a hydrophilic surface by creating L25 orthogonal arrays. The surface roughness values ranged between 2 and 26 µm. The lowest surface roughness with a value of 2.21 µm was achieved when the texture was processed with a frequency of 150 kHz, a fill spacing of 0.02 mm, a scan speed of 800 mm/s, a pulse width of 250 ns, and a cross-hatch strategy of 0°/90°. Considering the wettability test results, it was revealed that most of the textured surfaces have super hydrophilic and hydrophilic characteristics except the surface with a contact angle of 92.93°. The relevant surface was textured with 75 kHz frequency, 1000 mm/s scan speed, 0.05 mm fill spacing, 200 ns pulse width, and 45°/-45° cross-hatch strategy.

An efficient magnetothermal actuation setup for fast heating/cooling cycles or long-term induction heating of different magnetic nanoparticle classes

Alternating magnetic fields (AMFs) in the ∼100 kHz frequency regime cause magnetic nanoparticles (MNPs) to dissipate heat to their nanoscale environment. This mechanism is beneficial for a variety of applications in biomedicine and nanotechnology, such as localized heating of cancer tissue, actuation of drug release, or inducing conformational changes of molecules. However, engineering electromagnetic resonant circuits which generate fields to efficiently heat MNPs over long time scales, remains a challenge. In addition, many applications require fast heating/cooling cycles over ΔT= 5 °C–10 °C to switch the sample between different states. Here, we present a home-built magnetothermal actuation setup maximized in its efficiency to deliver stable AMFs as well as to enable fast heating/cooling cycles of MNP samples. The setup satisfies various demands, such as an elaborate cooling system to control heating of the circuit components as well as of the sample due to inductive losses. Fast cycles of remote sample heating/cooling (up to ±15 °C min−1) as well as long-term induction heating were monitored via contact-free thermal image recording at sub-mm resolution. Next to characterizing the improved hyperthermia setup, we demonstrate its applicability to heat different types of MNPs: ‘nanoflower’-shaped multicore iron oxide nanoparticles, core shell magnetite MNPs, as well as magnetosomes from magnetotactic bacteria (Magnetospirillum gryphiswaldense). MNPs are directly compared in their structure, surface charge, magnetic properties as well as heating response. Our work provides practical guidelines for AMF engineering and the monitoring of MNP heating for biomedical or nano-/biotechnological applications.

Structure, Microstructure, and Dielectric Properties of Bi&lt;sub&gt;0.5&lt;/sub&gt;(Na&lt;sub&gt;0.78&lt;/sub&gt;K&lt;sub&gt;0.22&lt;/sub&gt;)&lt;sub&gt;0.5&lt;/sub&gt;TiO&lt;sub&gt;3 &lt;/sub&gt;Lead-Free Ceramic

In this article, the structural, microstructural, and dielectric properties of Lead- free perovskite ceramic Bi0.5(Na0.78K0.22)0.5TiO3 [BNKT] have been reported. The material was synthesized through the solid-state reaction method. The compound formed is found to have a hexagonal structure, confirmed by XRD analysis of the sample. The microstructural analysis of the compound revealed the polycrystalline nature of the ceramic having quasi-cubic grain morphology with distinct grain boundaries. From the dielectric study, it was found that the dielectric constant increases with temperature and attained maximum value at temperature Tc = 335° C, after which it decreased. The frequency independence of transition temperature (Tc) suggested the classic ferroelectric behaviour of the compound. The broad dielectric peak around transition temperature confirms the relaxor behaviour of the compound as well as diffused phase transition at Tc. The value of the relative permittivity and loss tangent at ambient temperature for 1kHz frequency is 627 and 0.223 respectively. The synthesized material can be utilized for the fabrication of capacitors and energy storage applications.

Study on three-dimensional dielectrophoresis microfluidic chip for separation and enrichment of circulating tumor cells

BackgroundCirculating tumor cells (CTCs) which means tumor cells shed into the peripheral blood of humans, are one of the important indicators in the early and accurate detection of malignancy. ObjectiveThis paper is based on the principle of dielectrophoresis, the design and performance research of microfluidic microarray separating and enriching CTCs was carried out, and the separation and enriching of CTCs was realized by ultilizing the difference in dielectrophoretic force and the movement trajectories between CTCs and leukocytes. ResultsChip structure design and optimization based on the COMSOL software simulation tool, through the separation experiment of human breast cancer cell MCF-7 and white blood cells, 60 kHz was selected as the frequency of cell separation experiment. Taking human liver cancer cell SMMC-7721 and human leukocyte mixture as the research object, the chip separation and enrichment experiment of CTCs was conducted. At 5 V voltage and 60 kHz frequency, the maximum separation flux of three-dimensional dielectrophores is microfluidic chip for human liver cancer cell SMMC-7721 reached 1.1 mL/h, and the separation efficiency was about 94%. ConclusionThe results of this research have important implications for separating, sorting and detecting CTCs.