Microparticle manipulation using laser-induced thermophoresis and thermal convection flow

Abstract We demonstrate manipulation of microbeads with diameters from 1.5 to 10 µm and Jurkat cells within a thin fluidic device using the combined effect of thermophoresis and thermal convection. The heat flow is induced by localized absorption of laser light by a cluster of single walled carbon nanotubes, with no requirement for a treated substrate. Characterization of the system shows the speed of particle motion increases with optical power absorption and is also affected by particle size and corresponding particle suspension height within the fluid. Further analysis shows that the thermophoretic mobility (DT) is thermophobic in sign and increases linearly with particle diameter, reaching a value of 8 µm2 s−1 K−1 for a 10 µm polystyrene bead.

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SCALING ANALYSIS OF THE A-PHASE DYNAMICS DURING SLEEP

Fractals ◽

10.1142/s0218348x20500504 ◽

2020 ◽

Vol 28 (02) ◽

pp. 2050050

Author(s):

V. E. ARCE-GUEVARA ◽

M. O. MENDEZ ◽

J. S. MURGUÍA ◽

A. ALBA ◽

H. GONZÁLEZ-AGUILAR ◽

...

Keyword(s):

Binary Sequence ◽

Fluctuation Analysis ◽

Scaling Analysis ◽

Scaling Exponent ◽

Sleep State ◽

Phase Dynamics ◽

A Value ◽

Sleep Condition ◽

Detrended Fluctuation

In this work, the scaling behavior of the sleep process is evaluated by using detrended fluctuation analysis based on wavelets. The analysis is carried out from arrivals of short and recurrent cortical events called A-phases, which in turn build up the Cyclic Alternating Pattern phenomenon, and are classified in three types: A1, A2 and A3. In this study, 61 sleep recordings corresponding to healthy, nocturnal frontal lobe epilepsy patients and sleep-state misperception subjects, were analyzed. From the A-phase annotations, the onsets were extracted and a binary sequence with one second resolution was generated. An item in the sequence has a value of one if an A-phase onset occurs in the corresponding window, and a value of zero otherwise. In addition, we consider other different temporal resolutions from 2[Formula: see text]s to 256[Formula: see text]s. Furthermore, the same analysis was carried out for sequences obtained from the different types of A-phases and their combinations. The results of the numerical analysis showed a relationship between the time resolutions and the scaling exponents; specifically, for higher time resolutions a white noise behavior is observed, whereas for lower time resolutions a behavior towards to [Formula: see text]-noise is exhibited. Statistical differences among groups were observed by applying various wavelet functions from the Daubechies family and choosing the appropriate sequence of A-phase onsets. This scaling analysis allows the characterization of the free-scale dynamic of the sleep process that is specific for each sleep condition. The scaling exponent could be useful as a diagnosis parameter in clinics when sleep macrostructure does not offer enough information.

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Characterization of Chromium Compensated GaAs Sensors with the Charge-Integrating JUNGFRAU Readout Chip by Means of a Highly Collimated Pencil Beam

Sensors ◽

10.3390/s21041550 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1550

Author(s):

Dominic Greiffenberg ◽

Marie Andrä ◽

Rebecca Barten ◽

Anna Bergamaschi ◽

Martin Brückner ◽

...

Keyword(s):

Low Noise ◽

State University ◽

Noise Performance ◽

X Ray ◽

A Value ◽

Resolution Capability ◽

Sensor Properties ◽

Pixel Pitch ◽

Lower Noise

Chromium compensated GaAs or GaAs:Cr sensors provided by the Tomsk State University (Russia) were characterized using the low noise, charge integrating readout chip JUNGFRAU with a pixel pitch of 75 × 75 µm2 regarding its application as an X-ray detector at synchrotrons sources or FELs. Sensor properties such as dark current, resistivity, noise performance, spectral resolution capability and charge transport properties were measured and compared with results from a previous batch of GaAs:Cr sensors which were produced from wafers obtained from a different supplier. The properties of the sample from the later batch of sensors from 2017 show a resistivity of 1.69 × 109 Ω/cm, which is 47% higher compared to the previous batch from 2016. Moreover, its noise performance is 14% lower with a value of (101.65 ± 0.04) e− ENC and the resolution of a monochromatic 60 keV photo peak is significantly improved by 38% to a FWHM of 4.3%. Likely, this is due to improvements in charge collection, lower noise, and more homogeneous effective pixel size. In a previous work, a hole lifetime of 1.4 ns for GaAs:Cr sensors was determined for the sensors of the 2016 sensor batch, explaining the so-called “crater effect” which describes the occurrence of negative signals in the pixels around a pixel with a photon hit due to the missing hole contribution to the overall signal causing an incomplete signal induction. In this publication, the “crater effect” is further elaborated by measuring GaAs:Cr sensors using the sensors from 2017. The hole lifetime of these sensors was 2.5 ns. A focused photon beam was used to illuminate well defined positions along the pixels in order to corroborate the findings from the previous work and to further characterize the consequences of the “crater effect” on the detector operation.

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Synthesis and characterization of novel functionalized perarylated polysiloxane for proton exchange membrane fuel cells

MRS Advances ◽

10.1557/adv.2019.419 ◽

2019 ◽

Vol 4 (64) ◽

pp. 3579-3585

Author(s):

Guillermo M. González Guerra ◽

Alejandro Alatorre-Ordaz ◽

Gerardo González Garcia ◽

Jesus S. Jaime-Ferrer

Keyword(s):

Cyclic Voltammetry ◽

Fuel Cells ◽

Proton Exchange Membrane ◽

Area Under The Curve ◽

Chlorosulfonic Acid ◽

Proton Exchange ◽

Synthesis And Characterization ◽

A Value ◽

Exchange Membrane

ABSTRACTThis work presents the synthesis and characterization of a pearylated polysiloxane material (PAP) from a polycondensation reaction, followed by functionalization with HClSO3 by an electrophilic substitution reaction. According to the characterization techniques applied, a sulfonated pearylated polysiloxane was also obtained, (SPAP). The purpose of this sulfonated material is to obtain an ionomer able to be applied in hydrogen fuel cells of the proton exchange membrane kind (PEMFC). The reaction to produce the polysiloxane precursor was carried out with the commercial reagents: PhSiCl3, Ph2SiCl2 and Ph3SiCl in anhydrous THF at 75 °C and the SPAP material was obtained by sulfonation of the precursor with chlorosulfonic acid. PAP and SPAP were characterized by 1H, NMR for liquids, 29Si NMR for solids, IR-ATR, SEM, and cyclic voltammetry. The NMR 29Si spectra show that PAP and PAPS contain crosslinking regions due to PhSiCl3, growing chain zones due to Ph2SiCl2 and polymer termination zones due to Ph3SiCl, obtaining a mixture of siloxanes. The analysis by cyclic voltammetry indicates that by integrating the area under the curve of the adsorption peaks of H2, a value of 0.062 mC/cm2 is obtained, a value close to the commercial ionomer of Nafion®.

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Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705711404724 ◽

2011 ◽

Vol 24 (6) ◽

pp. 777-788 ◽

Cited By ~ 3

Author(s):

J.Z. Liang

Keyword(s):

Polymer Composites ◽

Volume Fraction ◽

Particle Diameter ◽

Interfacial Structure ◽

Interlayer Thickness ◽

Filled Polymer ◽

Mechanical And Physical Properties ◽

The Relationship ◽

Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

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Synthesis and Characterization of Polydimethylsiloxane (PDMS) with Medium Viscosity via Ring-Opening Polymerization

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1028.346 ◽

2021 ◽

Vol 1028 ◽

pp. 346-351

Author(s):

Soni Setiadji ◽

Zulfi Mofa Agasa ◽

Diba G Auliya ◽

Fitrilawati ◽

Norman Syakir ◽

...

Keyword(s):

Ring Opening ◽

Vitreoretinal Surgery ◽

High Viscosity ◽

Ring Opening Polymerization ◽

Vitreous Humour ◽

Synthesis And Characterization ◽

Low Viscosity ◽

A Value ◽

Medium Viscosity

Duration of use and injectability are external factors for Polydimethylsiloxane (PDMS) that needs to be considered when PDMS utilized as a vitreous substituted liquid in vitreoretinal surgery. In general, PDMS which has been used as a substitute for vitreous humour is PDMS with a low viscosity in the value about 1000 cSt and a high viscosity at a value of about 5000 cSt. Various deficiencies have been encountered from low and high viscosity of PDMS, causing research to be continued to obtain PDMS which has suitable properties as a substitute for vitreous humour. One of them is research to obtain medium viscosity of PDMS with a viscosity value of about 2000 cSt. Here, we reported synthesis and characterization of PDMS with medium viscosity in ranges from 1800 to 2600 mPas. PDMS was synthesized through Ring-Opening Polymerization (ROP) pathway using the monomer of Octamethylcyclotetrasiloxane (D4) and the chain terminator of Hexamethyldisiloxane (MM). Various concentrations of potassium hydroxide (KOH) of 3, 4, 6 and 8 %(w/v) were applied as initiator to form gel of PDMS. All synthesized PDMS samples were identified to have viscosity values of 1800-2600 mPas, refractive index values of 1.4042-1.4044 and surface tension values of 22-23 mN/m. Meanwhile, the results of Fourier-Transform Infrared (FTIR) measurement showed that the absorption peaks were similar to that of our previous report.

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