11 results on '"Ohadi, H"'
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2. Laser Writing of Parabolic Micromirrors with a High Numerical Aperture for Optical Trapping and Rotation
- Author
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Plaskocinski, T., Arita, Y., Bruce, G. D., Persheyev, S., Dholakia, K., Di Falco, A., and Ohadi, H.
- Subjects
Physics - Optics - Abstract
On-chip optical trapping systems allow for high scalability and lower the barrier to access. Systems capable of trapping multiple particles typically come with high cost and complexity. Here we present a technique for making parabolic mirrors with micron-size dimensions and high numerical apertures (NA>1). Over 350 mirrors are made by simple CO2 laser ablation of glass followed by gold deposition. We fabricate mirrors of arbitrary diameter and depth at a high throughput rate by carefully controlling the ablation parameters. We use the micromirrors for 3-dimensional optical trapping of microbeads in solution, achieving a maximum optical trap stiffness of 52 pN/{\mu}m/W. We then further demonstrate the viability of the mirrors as in-situ optical elements through the rotation of a vaterite particle using reflected circularly polarized light. The method used allows for rapid and highly customizable fabrication of dense optical arrays., Comment: 6 pages, 5 figures
- Published
- 2023
3. Laser writing of parabolic micromirrors with a high numerical aperture for optical trapping and rotation
- Author
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Plaskocinski, T., primary, Arita, Y., additional, Bruce, G. D., additional, Persheyev, S., additional, Dholakia, K., additional, Di Falco, A., additional, and Ohadi, H., additional
- Published
- 2023
- Full Text
- View/download PDF
4. Stochastic Single-Shot Polarization Pinning of Polariton Condensate at High Temperatures
- Author
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Balas, Y. C., primary, Sedov, E. S., additional, Paschos, G. G., additional, Hatzopoulos, Z., additional, Ohadi, H., additional, Kavokin, A. V., additional, and Savvidis, P. G., additional
- Published
- 2022
- Full Text
- View/download PDF
5. Umbilical cord blood thyroid hormones are inversely related to telomere length and mitochondrial DNA copy number.
- Author
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Ohadi H, Khalili P, Abasnezhad Kasrineh F, Esmaeili OS, Esmaeili Ranjbar F, Manshoori A, Hajizadeh MR, and Jalali Z
- Subjects
- Humans, Infant, Newborn, Animals, Male, Female, Pregnancy, Child, Preschool, DNA Copy Number Variations, Thyroid Hormones, Telomere genetics, Thyrotropin genetics, DNA, Mitochondrial genetics, Fetal Blood
- Abstract
Hypothyroidism has been linked to reduced mortality rate and increased lifespan and health span. Telomere shortening, enhanced oxidative stress, and reduced cellular mitochondrial content are important hallmarks of aging shown to be related to age-associated diseases. It was proposed that the status of these markers in early life can be predictive of lifespan and the predisposition to certain age-associated disease in adulthood. Animal studies indicated that prenatal injection of thyroid hormones affects postnatal telomere length. Here, we sought to determine whether thyroid hormones TSH and fT4 are related to the telomere length, mitochondrial DNA copy number (mtDNAcn), and oxidative stress resistance marker GPX in the cord blood of newborns. In this study, we analyzed 70 mothers (18-42 years) and neonate dyads born in 2022 at the Nik Nafs maternity Hospital in Rafsanjan. The relative telomere length (RTL) and mtDNAcn were measured in the genomic DNA of cord blood leukocytes using real-time PCR. GPX enzyme activity was measured in the serum using colorimetric assays. In this study the correlation between these markers and the cord blood TSH and fT4 hormones were assessed using regression models. We found a reverse relationship between TSH levels and RTL in the cord blood of neonates. Additionally, our results displayed increased TSH levels associated with enhanced GPX activity. Regarding the mitochondrial DNA copy number, we found an indirect relationship between fT4 level and mtDNAcn only in male newborns. Future analyses of various oxidative stress markers, mitochondrial biogenesis status, telomerase activity, and the level of DNA damage are warranted to demonstrate the underlying mechanism of our observations., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
6. Nonlinear Rydberg exciton-polaritons in Cu 2 O microcavities.
- Author
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Makhonin M, Delphan A, Song KW, Walker P, Isoniemi T, Claronino P, Orfanakis K, Rajendran SK, Ohadi H, Heckötter J, Assmann M, Bayer M, Tartakovskii A, Skolnick M, Kyriienko O, and Krizhanovskii D
- Abstract
Rydberg excitons (analogues of Rydberg atoms in condensed matter systems) are highly excited bound electron-hole states with large Bohr radii. The interaction between them as well as exciton coupling to light may lead to strong optical nonlinearity, with applications in sensing and quantum information processing. Here, we achieve strong effective photon-photon interactions (Kerr-like optical nonlinearity) via the Rydberg blockade phenomenon and the hybridisation of excitons and photons forming polaritons in a Cu2O-filled microresonator. Under pulsed resonant excitation polariton resonance frequencies are renormalised due to the reduction of the photon-exciton coupling with increasing exciton density. Theoretical analysis shows that the Rydberg blockade plays a major role in the experimentally observed scaling of the polariton nonlinearity coefficient as ∝ n
4.4±1.8 for principal quantum numbers up to n = 7. Such high principal quantum numbers studied in a polariton system for the first time are essential for realisation of high Rydberg optical nonlinearities, which paves the way towards quantum optical applications and fundamental studies of strongly correlated photonic (polaritonic) states in a solid state system., (© 2024. The Author(s).)- Published
- 2024
- Full Text
- View/download PDF
7. CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B leads to disruption of neural cell differentiation from NT2 cells.
- Author
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Bayat H, Mirahmadi M, Azarshin Z, Ohadi H, Delbari A, and Ohadi M
- Subjects
- Humans, Cell Differentiation genetics, Neurons metabolism, Membrane Glycoproteins metabolism, Nerve Tissue Proteins metabolism, CRISPR-Cas Systems, Microsatellite Repeats
- Abstract
The human neuron-specific gene, GPM6B (Glycoprotein membrane 6B), is considered a key gene in neural cell functionality. This gene contains an exceptionally long and strictly monomorphic short tandem repeat (STR) of 9-repeats, (GA)9. STRs in regulatory regions, may impact on the expression of nearby genes. We used CRISPR-based tool to delete this GA-repeat in NT2 cells, and analyzed the consequence of this deletion on GPM6B expression. Subsequently, the edited cells were induced to differentiate into neural cells, using retinoic acid (RA) treatment. Deletion of the GA-repeat significantly decreased the expression of GPM6B at the RNA (p < 0.05) and protein (40%) levels. Compared to the control cells, the edited cells showed dramatic decrease of the astrocyte and neural cell markers, including GFAP (0.77-fold), TUBB3 (0.57-fold), and MAP2 (0.2-fold). Subsequent sorting of the edited cells showed an increased number of NES (p < 0.01), but a decreased number of GFAP (p < 0.001), TUBB3 (p < 0.05), and MAP2 (p < 0.01), compared to the control cells. In conclusion, CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B, led to decreased expression of this gene, which in turn, disrupted differentiation of NT2 cells into neural cells., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
8. Highly-excited Rydberg excitons in synthetic thin-film cuprous oxide.
- Author
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DeLange J, Barua K, Paul AS, Ohadi H, Zwiller V, Steinhauer S, and Alaeian H
- Abstract
Cuprous oxide ([Formula: see text]) has recently emerged as a promising material in solid-state quantum technology, specifically for its excitonic Rydberg states characterized by large principal quantum numbers (n). The significant wavefunction size of these highly-excited states (proportional to [Formula: see text]) enables strong long-range dipole-dipole (proportional to [Formula: see text]) and van der Waals interactions (proportional to [Formula: see text]). Currently, the highest-lying Rydberg states are found in naturally occurring [Formula: see text]. However, for technological applications, the ability to grow high-quality synthetic samples is essential. The fabrication of thin-film [Formula: see text] samples is of particular interest as they hold potential for observing extreme single-photon nonlinearities through the Rydberg blockade. Nevertheless, due to the susceptibility of high-lying states to charged impurities, growing synthetic samples of sufficient quality poses a substantial challenge. This study successfully demonstrates the CMOS-compatible synthesis of a [Formula: see text] thin film on a transparent substrate that showcases Rydberg excitons up to [Formula: see text] which is readily suitable for photonic device fabrications. These findings mark a significant advancement towards the realization of scalable and on-chip integrable Rydberg quantum technologies., (© 2023. Springer Nature Limited.)
- Published
- 2023
- Full Text
- View/download PDF
9. Optically trapped room temperature polariton condensate in an organic semiconductor.
- Author
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Wei M, Verstraelen W, Orfanakis K, Ruseckas A, Liew TCH, Samuel IDW, Turnbull GA, and Ohadi H
- Abstract
The strong nonlinearities of exciton-polariton condensates in lattices make them suitable candidates for neuromorphic computing and physical simulations of complex problems. So far, all room temperature polariton condensate lattices have been achieved by nanoimprinting microcavities, which by nature lacks the crucial tunability required for realistic reconfigurable simulators. Here, we report the observation of a quantised oscillating nonlinear quantum fluid in 1D and 2D potentials in an organic microcavity at room temperature, achieved by an on-the-fly fully tuneable optical approach. Remarkably, the condensate is delocalised from the excitation region by macroscopic distances, leading both to longer coherence and a threshold one order of magnitude lower than that with a conventional Gaussian excitation profile. We observe different mode selection behaviour compared to inorganic materials, which highlights the anomalous scaling of blueshift with pump intensity and the presence of sizeable energy-relaxation mechanisms. Our work is a major step towards a fully tuneable polariton simulator at room temperature., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
10. Tandem repeats ubiquitously flank and contribute to translation initiation sites.
- Author
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Maddi AMA, Kavousi K, Arabfard M, Ohadi H, and Ohadi M
- Subjects
- Tandem Repeat Sequences
- Abstract
Background: While the evolutionary divergence of cis-regulatory sequences impacts translation initiation sites (TISs), the implication of tandem repeats (TRs) in TIS selection remains largely elusive. Here, we employed the TIS homology concept to study a possible link between TRs of all core lengths and repeats with TISs., Methods: Human, as reference sequence, and 83 other species were selected, and data was extracted on the entire protein-coding genes (n = 1,611,368) and transcripts (n = 2,730,515) annotated for those species from Ensembl 102. Following TIS identification, two different weighing vectors were employed to assign TIS homology, and the co-occurrence pattern of TISs with the upstream flanking TRs was studied in the selected species. The results were assessed in 10-fold cross-validation., Results: On average, every TIS was flanked by 1.19 TRs of various categories within its 120 bp upstream sequence, per species. We detected statistically significant enrichment of non-homologous human TISs co-occurring with human-specific TRs. On the contrary, homologous human TISs co-occurred significantly with non-human-specific TRs. 2991 human genes had at least one transcript, TIS of which was flanked by a human-specific TR. Text mining of a number of the identified genes, such as CACNA1A, EIF5AL1, FOXK1, GABRB2, MYH2, SLC6A8, and TTN, yielded predominant expression and functions in the human brain and/or skeletal muscle., Conclusion: We conclude that TRs ubiquitously flank and contribute to TIS selection at the trans-species level. Future functional analyses, such as a combination of genome editing strategies and in vitro protein synthesis may be employed to further investigate the impact of TRs on TIS selection., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
11. Rydberg exciton-polaritons in a Cu 2 O microcavity.
- Author
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Orfanakis K, Rajendran SK, Walther V, Volz T, Pohl T, and Ohadi H
- Abstract
Giant Rydberg excitons with principal quantum numbers as high as n = 25 have been observed in cuprous oxide (Cu
2 O), a semiconductor in which the exciton diameter can become as large as ∼1 μm. The giant dimension of these excitons results in excitonic interaction enhancements of orders of magnitude. Rydberg exciton-polaritons, formed by the strong coupling of Rydberg excitons to cavity photons, are a promising route to exploit these interactions and achieve a scalable, strongly correlated solid-state platform. However, the strong coupling of these excitons to cavity photons has remained elusive. Here, by embedding a thin Cu2 O crystal into a Fabry-Pérot microcavity, we achieve strong coupling of light to Cu2 O Rydberg excitons up to n = 6 and demonstrate the formation of Cu2 O Rydberg exciton-polaritons. These results pave the way towards realizing strongly interacting exciton-polaritons and exploring strongly correlated phases of matter using light on a chip., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)- Published
- 2022
- Full Text
- View/download PDF
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