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1.
Cancers (Basel) ; 16(8)2024 Apr 22.
Article de Anglais | MEDLINE | ID: mdl-38672694

RÉSUMÉ

The Cancers Editorial Office retracts the article, "MicroRNA-21 Plays Multiple Oncometabolic Roles in the Process of NAFLD-Related Hepatocellular Carcinoma via PI3K/AKT, TGF-ß, and STAT3 Signaling" [...].

2.
Cancers (Basel) ; 16(3)2024 Jan 31.
Article de Anglais | MEDLINE | ID: mdl-38339375

RÉSUMÉ

Although Otto Warburg may be right about the role of glycolysis versus OXPHOS in cancer metabolism, it remains unclear whether an altered metabolism is causative or correlative and is the main driver or a mere passenger in the pathogenesis of cancer. Currently, most of our successful treatments are designed to eliminate non-cancer stem cells (non-CSCs) such as differentiated cancer cells. When the treatments also happen to control CSCs or the stem-ness niche, it is often unintended, unexpected, or undetected for lack of a pertinent theory about the origin of cancer that clarifies whether cancer is a metabolic, genetic, or stem cell disease. Perhaps cellular context matters. After all, metabolic activity may be different in different cell types and their respective microenvironments-whether it is in a normal progenitor stem cell vs. progeny differentiated cell and whether it is in a malignant CSC vs. non-CSC. In this perspective, we re-examine different types of cellular metabolism, e.g., glycolytic vs. mitochondrial, of glucose, glutamine, arginine, and fatty acids in CSCs and non-CSCs. We revisit the Warburg effect, an obesity epidemic, the aspartame story, and a ketogenic diet. We propose that a pertinent scientific theory about the origin of cancer and of cancer metabolism influences the direction of cancer research as well as the design of drug versus therapy development in cancer care.

3.
J Phys Chem B ; 128(1): 67-76, 2024 01 11.
Article de Anglais | MEDLINE | ID: mdl-38130113

RÉSUMÉ

Determining changes in the protein's thermal stability following mutations is critical in protein engineering and understanding pathogenic missense mutations. Despite the development of various computational methods to predict the effects of single-point mutations, their accuracy remains limited. In this study, we propose a new computational method, OmeDDG, that more accurately predicts mutation-induced Gibbs free energy changes in protein folding (ΔΔG). OmeDDG takes the sequences of wild-type and mutant proteins as input, utilizes OmegaFold to obtain the 3D structure, employs a convolutional neural network to extract structural features, and combines them with protein mutation features and pretraining features to predict the stability of single-point mutations in proteins. We performed a comprehensive comparison between OmeDDG and other available prediction methods on four blind test datasets, confirming that OmeDDG can effectively enhance protein mutation prediction performance. Notably, on the antisymmetric dataset Ssym, OmeDDG achieves the best performance, demonstrating favorable antisymmetry with PCC = 0.79 and RMSE = 0.96 for forward mutations and PCC = 0.77 and RMSE = 0.97 for reverse mutant types.


Sujet(s)
Mutation ponctuelle , Protéines , Mutation , Protéines/génétique , Protéines/composition chimique , Protéines mutantes/génétique , Pliage des protéines , Stabilité protéique
4.
Cancers (Basel) ; 15(23)2023 Nov 22.
Article de Anglais | MEDLINE | ID: mdl-38067237

RÉSUMÉ

Biomarkers play a crucial role in the diagnosis, prognosis, and therapeutics of cancer. We use biomarkers to identify, image, monitor, and target cancer. In many respects, the discovery of pertinent biomarkers that distinguish fulminant from indolent neoplasms and sensitive from refractory malignancies would be a holy grail of cancer research and therapy. We propose that a stem cell versus genetic theory of cancer may not only enable us to track and trace the biological evolution of cancer but also empower us to attenuate its clinical course and optimize the clinical outcome of patients with cancer. Hence, a biomarker that identifies cancer stem cells (CSCs) and distinguishes them from non-CSCs may serve to elucidate inter-tumoral and intra-tumoral heterogeneity, elevate the values and utility of current prognostic and predictive tests, and enhance drug versus therapy development in cancer care. From this perspective, we focus on CSC biomarkers and discuss stemness or stem-like biomarkers in the context of a unified theory and a consideration of stem cell versus genetic origin. We review their role in primary and mixed tumors, in the elaboration of tumor subtypes, and in the imaging and monitoring of minimal residual diseases. We investigate how scientific theories influence the direction of scientific research and interpretation of experimental results, and how genomics and epigenomics affect the dynamics and trajectories of biomarkers in the conduct of cancer research and in the practice of cancer care.

5.
J Am Geriatr Soc ; 71(3): 720-729, 2023 03.
Article de Anglais | MEDLINE | ID: mdl-36515210

RÉSUMÉ

BACKGROUND: Asymptomatic diabetes testing may be of limited value for older nursing home residents, but most diabetes guidelines lack upper-age cutoffs for screening cessation. We evaluated patterns of glycated hemoglobin (HbA1c) and serum blood glucose (SBG) testing among older residents without diabetes in Ontario, Canada. METHODS: This population-based retrospective cohort study used provincial health administrative data from ICES to identify older nursing home residents in Ontario without diabetes between January 1, 2015 and December 31, 2018. We examined HbA1c and glucose testing rates overall, by age, sex, and near end-of-life. The number of tests needed to identify one case of diabetes (using HbA1c thresholds of 6.5% and 8.0%) were also calculated. RESULTS: Among 102,923 older nursing home residents (70.3% women; average age 85.6 ± SD 7.7 years), 46.1% of residents received ≥1 HbA1c test over an average follow-up period of 2.15 (± SD 1.49) years, and 18.2% of these tested residents received ≥4 HbA1c tests. The crude HbA1c testing rate was 52.6 tests/100 person-years (95% CI 52.3-52.9). Testing rates among residents aged ≥80 years was 50.7 HbA1c tests/100 person-years (95% CI 50.4-51.0), and 47.8 tests/100 person-years (95% CI 46.5-49.0) among residents near end-of-life. The number of tests to identify a case of diabetes (HbA1c ≥ 6.5%) was 44, while the number of tests to identify a case of actionable diabetes (HbA1c ≥ 8%) was 310. Less than 1% of residents with an HbA1c test met criteria for actionable diabetes. CONCLUSIONS: Nursing home residents without diabetes receive frequent diabetes testing, with high testing rates even in residents over 80 years old and residents near end-of-life. The high number of tests needed to identify a case of actionable diabetes highlights the urgent need to re-evaluate diabetes testing practices in nursing homes.


Sujet(s)
Diabète , Humains , Femelle , Sujet âgé , Sujet âgé de 80 ans ou plus , Mâle , Hémoglobine glyquée , Études rétrospectives , Ontario/épidémiologie , Diabète/diagnostic , Diabète/épidémiologie , Maisons de repos , Mort
6.
AAPS PharmSciTech ; 23(7): 268, 2022 Sep 27.
Article de Anglais | MEDLINE | ID: mdl-36168006

RÉSUMÉ

Generic drugs play an important role in public health. However, the first review cycle approval rate for Abbreviated New Drug Applications (ANDAs) is generally low. To identify if the drug product (DP) manufacturing related deficiencies are the potential root causes of low first review cycle approval of the modified release (MR) tablet ANDAs, we collected and analyzed the review recommendations from each review discipline and the DP manufacturing (process and facility) related deficiencies for original MR tablet ANDAs submitted between FY17 and FY19. We identified 193 original MR tablet ANDAs. The analysis showed that 12% of the applications were approved in first review cycle, while 88% received complete responses (CR). Of the 169 CR applications, 91% were found inadequate for multiple review disciplines. A total of 1345 DP manufacturing process-related deficiencies were issued to 184 ANDAs during the first review cycle. We have identified common deficiencies across ANDAs based on DP manufacturing process categories. The top deficiencies cited reasons include facilities are out of compliance/not ready to commercialize/not ready for inspection; critical process parameter (CPP) ranges are not proposed/proposed CPP ranges are too wide and/or not supported by studied range and no in-process controls (IPCs) are proposed/proposed IPCs acceptance criteria (limits) are too wide and/or not supported by observed data etc. Avoiding the common DP manufacturing deficiencies may reduce the need for issuing DP manufacturing related deficiencies in information requests (IRs), discipline review letters (DRLs), and CRs for MR tablet ANDAs.


Sujet(s)
Agrément de médicaments , Médicaments génériques , Comprimés , Équivalence thérapeutique , États-Unis , Food and Drug Administration (USA)
7.
Biomarkers ; 27(7): 701-707, 2022 Nov.
Article de Anglais | MEDLINE | ID: mdl-35830714

RÉSUMÉ

PURPOSE: Oxidative stress has impacts on the KRas and Nrf2/Keap1 pathways, which have multiple interactions with each other and play important roles in colorectal cancer (CRC). This study investigated the expressions of proteins in the KRas and Nrf2/Keap1 pathways and their associations with clinicopathological features in CRC. METHODS: The protein levels of Nrf2, Keap1, Bach1, p62, HO1, KRas, Erk, Raf1 and PI3K in both the tumour and normal tissues of 60 CRC subjects were determined by Western blot and their T/N (tumour/normal tissue) ratios were correlated with clinicopathological features. RESULTS: The T/N ratios of proteins in the KRas and Nrf2/Keap1 pathways had correlation patterns and proximity profiles in cluster dendrograms different in CRC with different status of lymphovascular invasion (LVI) or lymph node/distant metastases. The Keap1 protein T/N ratio was a significant predictor (odd ratio: 2.24; 95% confidence interval: 1.26 - 4.38) of LVI, which in turn predicted metastases (11.0; 3.49 - 39.8). CONCLUSION: The interactions between the KRas and Nrf2/Keap1 pathways may be affected differently by LVI and metastases, and the protein T/N ratio of Keap1 may be helpful for predicting LVI in CRC.


Sujet(s)
Tumeurs colorectales , Facteur-2 apparenté à NF-E2 , Humains , Protéine-1 de type kelch associée à ECH/métabolisme , Facteur-2 apparenté à NF-E2/métabolisme , Corrélation de données , Tumeurs colorectales/métabolisme , Métastase lymphatique , Phosphatidylinositol 3-kinases , Protéines proto-oncogènes p21(ras)/génétique
8.
Adv Sci (Weinh) ; 9(25): e2201409, 2022 09.
Article de Anglais | MEDLINE | ID: mdl-35822667

RÉSUMÉ

The quest for rejuvenation and prolonged lifespan through transfusion of young blood has been studied for decades with the hope of unlocking the mystery of the key substance(s) that exists in the circulating blood of juvenile organisms. However, a pivotal mediator has yet been identified. Here, atypical findings are presented that are observed in a knockin mouse model carrying a lysine to arginine substitution at residue 74 of Krüppel-like factor 1 (KLF1/EKLF), the SUMOylation-deficient Klf1K74R/K74R mouse, that displayed significant improvement in geriatric disorders and lifespan extension. Klf1K74R/K74R mice exhibit a marked delay in age-related physical performance decline and disease progression as evidenced by physiological and pathological examinations. Furthermore, the KLF1(K74R) knockin affects a subset of lymphoid lineage cells; the abundance of tumor infiltrating effector CD8+ T cells and NKT cells is increased resulting in antitumor immune enhancement in response to tumor cell administration. Significantly, infusion of hematopoietic stem cells (HSCs) from Klf1K74R/K74R mice extends the lifespan of the wild-type mice. The Klf1K74R/K74R mice appear to be an ideal animal model system for further understanding of the molecular/cellular basis of aging and development of new strategies for antiaging and prevention/treatment of age-related diseases thus extending the healthspan as well as lifespan.


Sujet(s)
Longévité , Sumoylation , Animaux , Lymphocytes T CD8+ , Cellules souches hématopoïétiques , Longévité/génétique , Souris
9.
Article de Anglais | MEDLINE | ID: mdl-35228756

RÉSUMÉ

AIM: Activating mutations in the epidermal growth factor receptor (EGFR) are predominantly detected in pulmonary adenocarcinoma and have been reported in small cell lung cancer (SCLC) for decades. This retrospective single-center study aimed to determine the frequency and types of EGFR mutations in SCLC in Taiwan. METHODS: This study comprises a consecutive cohort of 161 patients histologically diagnosed with SCLC between January 1992 and August 2014 at the Department of Pathology in Keelung Chang Gung Memorial Hospital, Taiwan. Archived formalin-fixed paraffin-embedded sections from 71 patients were eligible for molecular analysis. EGFR mutation analysis was performed using a fully-automated IdyllaTM EGFR Mutation Test and confirmed a comparable result through Qiagen Therascreen® EGFR RGQ PCR. In addition, EGFR gene copy number was assessed in EGFR-mutated tumors by fluorescence in situ hybridization (FISH). RESULTS: Mutational status of the EGFR gene was successfully analyzed in 63 specimens by both IdyllaTM and Qiagen platforms. Both methods detected L858R point mutation in exon 21 in an 81-year-old female and a 47-year-old male non-smoker. Both tumors show no concurrent EGFR gene amplification. The overall agreement between results obtained with the Idylla™ EGFR Mutation Test and Qiagen Therascreen® EGFR RGQ PCR was 100% Conclusions. Our results showed that EGFR mutation is a rare mutation type in a consecutive series of de novo SCLC. Furthermore, the performance of Idylla™ EGFR Mutation Test and Qiagen Therascreen® EGFR RGQ PCR on archived paraffin sections of limited quantities is available with the high agreement of results.


Sujet(s)
Récepteurs ErbB , Tumeurs du poumon , Carcinome pulmonaire à petites cellules , Femelle , Humains , Mâle , Carcinome pulmonaire non à petites cellules/diagnostic , Analyse de mutations d'ADN/méthodes , Récepteurs ErbB/génétique , Formaldéhyde , Hybridation fluorescente in situ , Tumeurs du poumon/diagnostic , Mutation , Paraffine , Études rétrospectives , Carcinome pulmonaire à petites cellules/diagnostic , Carcinome pulmonaire à petites cellules/génétique
11.
Pharmacol Ther ; 233: 108033, 2022 05.
Article de Anglais | MEDLINE | ID: mdl-34763011

RÉSUMÉ

Spexin is the most recently discovered member of the galanin/kisspeptin/spexin family of peptides. This 14-amino acid peptide is highly conserved and is implicated in homeostatic functions including, but not limited to, metabolism, energy homeostasis, and reproduction. Spexin is expressed by neurons in the hypothalamus, which coordinate energy homeostasis and reproduction. Critically, levels of spexin appear to be altered in disorders related to energy homeostasis and reproduction, such as obesity, diabetes, and polycystic ovarian syndrome. In this review, we discuss the evidence for the involvement of spexin in the hypothalamic control of energy homeostasis and reproduction. The anorexigenic properties of spexin have been attributed to its effects on the energy-regulating neuropeptide Y/agouti-related peptide neurons and proopiomelanocortin neurons. While the role of spexin in reproduction remains unclear, there is evidence that gonadotropin-releasing hormone expressing neurons may produce and respond to spexin. Furthermore, we discuss the disorders and concomitant treatments, which have been reported to alter spexin expression, as well as the underlying signaling mechanisms that may be involved. Finally, we discuss the biochemical basis of spexin, its interaction with its cognate receptors, and how this information can be adapted to develop therapeutics for disorders related to the alteration of energy homeostasis and reproduction.


Sujet(s)
Hypothalamus , Hormones peptidiques , Métabolisme énergétique/physiologie , Hormone de libération des gonadotrophines , Homéostasie , Humains , Hypothalamus/métabolisme , Hormones peptidiques/métabolisme , Reproduction/physiologie
12.
Front Pediatr ; 9: 788336, 2021.
Article de Anglais | MEDLINE | ID: mdl-34926357

RÉSUMÉ

Background: Primary spontaneous pneumothorax is potentially life-threatening, and its recurrence is always a serious problem. Pathological examination provides molecular insights into the pathophysiology of primary spontaneous pneumothorax. Objectives: To investigate the association of histopathologic features of primary spontaneous pneumothorax with matrix metalloproteinase expression and their relevance to the recurrence. Methods: A total of 217 tissue section slides in 172 adolescent patients with primary spontaneous pneumothorax were retrospectively reviewed from January 2001 to June 2020. All histopathologic features were recorded and pathologic findings related to ipsilateral recurrence and second surgery were analyzed. Serum levels of matrix metalloproteinases were prospectively measured in 25 primary spontaneous pneumothorax patients receiving surgery and 18 healthy controls. Their relevance to the histopathologic features of primary spontaneous pneumothorax related to its recurrence was also examined. Results: The major presenting histopathologic findings of primary spontaneous pneumothorax were bleb/bulla (98%) followed by fibrosis (68%). Low prevalence of the pathologic findings of granulation tissue and macrophage accumulation were significantly associated with recurrent primary spontaneous pneumothorax, whereas fibrosis was significantly higher in patients receiving more than once surgery. Furthermore, the ratios of matrix metalloproteinase-2/tissue inhibitor of metalloproteinase-1 and matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 were significantly higher in theses pathological findings as well as multinucleated giant cells and mesothelial cell hyperplasia in comparison with healthy controls. Conclusions: Low prevalence of macrophage accumulation and granulation tissue related to the overexpression of matrix metalloproteinase-2 and-9 activities may contribute to healing impairment and primary spontaneous pneumothorax recurrence.

13.
Polymers (Basel) ; 13(19)2021 Sep 30.
Article de Anglais | MEDLINE | ID: mdl-34641168

RÉSUMÉ

The materials for large scale fused filament fabrication (FFF) are not yet designed to resist thermal degradation. This research presents a novel polymer blend of polylactic acid with polypropylene for FFF, purposefully designed with minimum feasible chemical grafting and overwhelming physical interlocking to sustain thermal degradation. Multi-level general full factorial ANOVA is performed for the analysis of thermal effects. The statistical results are further investigated and validated using different thermo-chemical and visual techniques. For example, Fourier transform infrared spectroscopy (FTIR) analyzes the effects of blending and degradation on intermolecular interactions. Differential scanning calorimetry (DSC) investigates the nature of blending (grafting or interlocking) and effects of degradation on thermal properties. Thermogravimetric analysis (TGA) validates the extent of chemical grafting and physical interlocking detected in FTIR and DSC. Scanning electron microscopy (SEM) is used to analyze the morphology and phase separation. The novel approach of overwhelmed physical interlocking and minimum chemical grafting for manufacturing 3D printing blends results in high structural stability (mechanical and intermolecular) against thermal degradation as compared to neat PLA.

14.
J Neurochem ; 159(3): 574-589, 2021 11.
Article de Anglais | MEDLINE | ID: mdl-34482548

RÉSUMÉ

A contributing factor to the development of obesity is the consumption of a diet high in saturated fatty acids, such as palmitate. These fats induce hypothalamic neuroinflammation, which dysregulates neuronal function and induces orexigenic neuropeptide Y (Npy) to promote food intake. An inflammatory cytokine array identified multiple candidates that could mediate palmitate-induced up-regulation of Npy mRNA levels. Of these, visfatin or nicotinamide phosphoribosyltransferase (NAMPT), macrophage migratory inhibitory factor (MIF), and IL-17F were chosen for further study. Direct treatment of the neuropeptide Y/agouti-related peptide (NPY/AgRP)-expressing mHypoE-46 neuronal cell line with the aforementioned cytokines demonstrated that visfatin could directly induce Npy mRNA expression. Preventing the intracellular metabolism of palmitate through long-chain acyl-CoA synthetase (ACSL) inhibition was sufficient to block the palmitate-mediated increase in Npy gene expression. Furthermore, thin-layer chromatography revealed that in neurons, palmitate is readily incorporated into ceramides and defined species of phospholipids. Exogenous C16 ceramide, dipalmitoyl-phosphatidylcholine, and dipalmitoyl-phosphatidylethanolamine were sufficient to significantly induce Npy expression. This study suggests that the intracellular metabolism of palmitate and elevation of metabolites, including ceramide and phospholipids, are responsible for the palmitate-mediated induction of the potent orexigen Npy. Furthermore, this suggests that the regulation of Npy expression is less reliant on inflammatory cytokines per se than palmitate metabolites in a model of NPY/AgRP neurons. These lipid species likely induce detrimental downstream cellular signaling events ultimately causing an increase in feeding, resulting in an overweight phenotype and/or obesity.


Sujet(s)
Cytokines/pharmacologie , Neuropeptide Y/biosynthèse , Palmitates/pharmacologie , Acyl coenzyme A/métabolisme , Animaux , Lignée cellulaire , Céramides/métabolisme , Milieux de culture conditionnés , Alimentation riche en graisse , Expression des gènes/effets des médicaments et des substances chimiques , Mâle , Souris , Souris de lignée C57BL , Neurones/métabolisme , Nicotinamide phosphoribosyltransferase/pharmacologie , ARN messager/biosynthèse , ARN messager/génétique
15.
Nat Neurosci ; 24(7): 907-912, 2021 07.
Article de Anglais | MEDLINE | ID: mdl-33972802

RÉSUMÉ

Physiological need states direct decision-making toward re-establishing homeostasis. Using a two-alternative forced choice task for mice that models elements of human decisions, we found that varying hunger and thirst states caused need-inappropriate choices, such as food seeking when thirsty. These results show limits on interoceptive knowledge of hunger and thirst states to guide decision-making. Instead, need states were identified after food and water consumption by outcome evaluation, which depended on the medial prefrontal cortex.


Sujet(s)
Prise de décision/physiologie , Faim/physiologie , Cortex préfrontal/physiologie , Soif/physiologie , Animaux , Femelle , Intéroception/physiologie , Mâle , Souris
16.
Healthcare (Basel) ; 9(5)2021 Apr 21.
Article de Anglais | MEDLINE | ID: mdl-33918991

RÉSUMÉ

(1) Background: Toxoplasmic lymphadenitis (TL), caused by the protozoan Toxoplasma gondii, is a worldwide zoonosis. We report a case of TL in the head and neck region diagnosed using ultrasound (US)-guided fine needle aspiration cytology (FNAC), serological tests, and pathological findings. (2) Case Presentation: A 51-year-old female with a chief complaint of a left posterior neck mass that had been growing for approximately 2 weeks. TL was confirmed by histopathological examinations and serological tests. US-guided FNAC and en bloc resection of the lymph node were performed. The diagnosis was confirmed as TL in the neck. (3) Conclusions: We suggest that US-guided FNAC should be considered as the first-line test for assessing a tiny mass before a definitive treatment is chosen.

17.
Cancers (Basel) ; 13(5)2021 Feb 24.
Article de Anglais | MEDLINE | ID: mdl-33668153

RÉSUMÉ

MicroRNA-21 (miR-21) is one of the most frequently upregulated miRNAs in liver diseases such as nonalcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC). However, mechanistic pathways that connect NAFLD and HCC remain elusive. We developed a doxycycline (Dox)-inducible transgenic zebrafish model (LmiR21) which exhibited an upregulation of miR-21 in the liver, which in turn induced the full spectrum of NAFLD, including steatosis, inflammation, fibrosis, and HCC, in the LmiR21 fish. Diethylnitrosamine (DEN) treatment led to accelerated liver tumor formation and exacerbated their aggressiveness. Moreover, prolonged miR-21 expression for up to ten months induced nonalcoholic steatohepatitis (NASH)-related HCC (NAHCC). Immunoblotting and immunostaining confirmed the presence of miR-21 regulatory proteins (i.e., PTEN, SMAD7, p-AKT, p-SMAD3, and p-STAT3) in human nonviral HCC tissues and LmiR21 models. Thus, we demonstrated that miR-21 can induce NAHCC via at least three mechanisms: First, the occurrence of hepatic steatosis increases with the decrease of ptenb, pparaa, and activation of the PI3K/AKT pathway; second, miR-21 induces hepatic inflammation (or NASH) through an increase in inflammatory gene expression via STAT3 signaling pathways, and induces liver fibrosis through hepatic stellate cell (HSC) activation and collagen deposition via TGF-ß/Smad3/Smad7 signaling pathways; finally, oncogenic activation of Smad3/Stat3 signaling pathways induces HCC. Our LmiR21 models showed similar molecular pathology to the human cancer samples in terms of initiation of lipid metabolism disorder, inflammation, fibrosis and activation of the PI3K/AKT, TGF-ß/SMADs and STAT3 (PTS) oncogenic signaling pathways. Our findings indicate that miR-21 plays critical roles in the mechanistic perspectives of NAHCC development via the PTS signaling networks.

18.
Chem Rec ; 21(6): 1473-1488, 2021 Jun.
Article de Anglais | MEDLINE | ID: mdl-33661570

RÉSUMÉ

Femtosecond (fs) laser trapping dynamics is summarized for silica, hydrophobically modified silica, and polystyrene nanoparticles (NPs) in aqueous solution, highlighting their distinct optical trapping dynamics under CW laser. Mutually repulsive silica nanoparticles are tightly confined under fs laser compared to CW laser trapping and, upon increasing laser power, they are ejected from the focus as an assembly. Hydrophobically modified silica and polystyrene (PS) NPs are sequentially ejected just like a stream or ablated, giving bubbles. The ejection and bubbling take place with the direction perpendicular to laser polarization and its direction is randomly switched from one to the other. These characteristic features are interpreted from the viewpoint of single assembly formation of NPs at an asymmetric position in the optical potential. Temporal change in optical forces map is prepared for a single PS NP by calculating scattering, gradient, and temporal forces. The relative contribution of the forces changes with the volume increase of the assembly and, when the pushing force along the trapping pulse propagation overcome the gradient in the focal plane, the assembly undergoes the ejection. Further fs multiphoton absorption is induced for the larger assembly leading to bubble generation. The assembling, ejection, and bubbling dynamics of NPs are characteristic features of pulsed optical force and are considered as a new platform for developing new material fabrication method.

19.
JASA Express Lett ; 1(7): 072802, 2021 07.
Article de Anglais | MEDLINE | ID: mdl-36154648

RÉSUMÉ

A bio-inspired acoustic sensor for sound source localization is presented, mimicking the internally coupled ears found in many terrestrial vertebrates and insects. It consists of two aluminum diaphragms coupled by a U-shaped cavity and detected by a low-coherence fiber optic interferometer system. A large-scale prototype with a center-to-center separation of 1″ is fabricated and experimentally demonstrated to amplify the interaural phase difference by a factor of 2 to 4 for a wide frequency range (0.5-2 kHz), which agrees well with simulation. This work presents a mechanism of using cavity-coupled diaphragms to develop acoustic sensors for sound source localization.


Sujet(s)
Muscle diaphragme , Localisation sonore , Acoustique , Aluminium , Animaux , Oreille
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