71 research outputs found
Red Blood Cells from Individuals with Abdominal Obesity or Metabolic Abnormalities Exhibit Less Deformability upon Entering a Constriction.
Abdominal obesity and metabolic syndrome (MS) are multifactorial conditions associated with increased risk of cardiovascular disease and type II diabetes mellitus. Previous work has demonstrated that the hemorheological profile is altered in patients with abdominal obesity and MS, as evidenced for example by increased whole blood viscosity. To date, however, no studies have examined red blood cell (RBC) deformability of blood from individuals with obesity or metabolic abnormalities under typical physiological flow conditions. In this study, we pumped RBCs through a constriction in a microfluidic device and used high speed video to visualize and track the mechanical behavior of ~8,000 RBCs obtained from either healthy individuals (n = 5) or obese participants with metabolic abnormalities (OMA) (n = 4). We demonstrate that the OMA+ cells stretched on average about 25% less than the healthy controls. Furthermore, we examined the effects of ingesting a high-fat meal on RBC mechanical dynamics, and found that the postprandial period has only a weak effect on the stretching dynamics exhibited by OMA+ cells. The results suggest that chronic rigidification of RBCs plays a key role in the increased blood pressure and increased whole blood viscosity observed in OMA individuals and was independent of an acute response triggered by consumption of a high-fat meal
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Effect of voicing and articulation manner on aerosol particle emission during human speech.
Previously, we demonstrated a strong correlation between the amplitude of human speech and the emission rate of micron-scale expiratory aerosol particles, which are believed to play a role in respiratory disease transmission. To further those findings, here we systematically investigate the effect of different 'phones' (the basic sound units of speech) on the emission of particles from the human respiratory tract during speech. We measured the respiratory particle emission rates of 56 healthy human volunteers voicing specific phones, both in isolation and in the context of a standard spoken text. We found that certain phones are associated with significantly higher particle production; for example, the vowel /i/ ("need," "sea") produces more particles than /É‘/ ("saw," "hot") or /u/ ("blue," "mood"), while disyllabic words including voiced plosive consonants (e.g., /d/, /b/, /g/) yield more particles than words with voiceless fricatives (e.g., /s/, /h/, /f/). These trends for discrete phones and words were corroborated by the time-resolved particle emission rates as volunteers read aloud from a standard text passage that incorporates a broad range of the phones present in spoken English. Our measurements showed that particle emission rates were positively correlated with the vowel content of a phrase; conversely, particle emission decreased during phrases with a high fraction of voiceless fricatives. Our particle emission data is broadly consistent with prior measurements of the egressive airflow rate associated with the vocalization of various phones that differ in voicing and articulation. These results suggest that airborne transmission of respiratory pathogens via speech aerosol particles could be modulated by specific phonetic characteristics of the language spoken by a given human population, along with other, more frequently considered epidemiological variables
Controlling the direction of steady electric fields in liquid using non-antiperiodic potentials
When applying an oscillatory electric potential to an electrolyte solution,
it is commonly assumed that the choice of which electrode is grounded or
powered does not matter because the time-average of the electric potential is
zero. Recent theoretical, numerical, and experimental work, however, has
established that certain types of multimodal oscillatory potentials that are
"non-antiperodic" can induce a net steady field toward either the grounded or
powered electrode [Hashemi et al., Phys. Rev. E 105, 065001 (2022)]. Here, we
elaborate on the nature of these steady fields through numerical and
theoretical analyses of the asymmetric rectified electric field (AREF) that
occurs in electrolytes where the cations and anions have different mobilities.
We demonstrate that AREFs induced by a non-antiperiodic electric potential,
e.g., by a two-mode waveform with modes at 2 and 3 Hz, invariably yields a
steady field that is spatially dissymmetric between two parallel electrodes,
such that swapping which electrode is powered changes the direction of the
field. Additionally, using a perturbation expansion, we demonstrate that the
dissymmetric AREF occurs due to odd nonlinear orders of the applied potential.
We further generalize the theory by demonstrating that the dissymmetric field
occurs for all classes of zero-time-average (no dc bias) periodic potentials,
including triangular and rectangular pulses, and we discuss how these steady
fields can tremendously change the interpretation, design, and applications of
electrochemical and electrokinetic systems
In-situ USAXS/SAXS Investigation of Tunable Structural Color in Amorphous Photonic Crystals during Electrophoretic Deposition
Amorphous photonic crystals (APCs) formed via electrophoretic deposition (EPD) exhibit non-iridescent, angle-independent, structural colors believed to arise from changes in the particle-particle interactions and inter-particle spacing, representing a potential new paradigm for display technologies. However, inter-particle dynamics on nanometer length scales that govern (and enable control over) the displayed color, crystallinity, and other characteristics of the photonic structures, are not well understood. Unfortunately, typical lab-based characterization techniques such as SEM, TEM, and Computed Tomography (CT) are generally performed ex-situ once the sample deposit has been dried. In this work, in-situ USAXS/SAXS/WAXS studies of three-dimensional colloidal particle arrays (of varying particle size and concentration) were performed in order to identify their structural response to applied external electric fields. This data was compared to simultaneously acquired UV-Vis spectra to tie the overall electrically induced structure of the APCs directly to the observed changes in visible color. The structural evolution of the APCs provides new information regarding the correlation between nano-scale particle-particle interactions and the corresponding optical response. To our knowledge, there has been no other prior studies examining the structure of APCs during the application of an electric field. This novel, in-situ USAXS study has helped to gain a better fundamental understanding of how the properties of APCs can be controlled for the advancement of optical displays.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-725437-DRAF
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