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Gradient forces on double negative (DNG) spherical dielectric particles are theoretically evaluated for v-th Bessel beams supposing geometrical optics approximations based on momentum transfer. For the first time in the literature, comparisons between these forces for double positive (DPS) and DNG particles are reported. We conclude that, contrary to the conventional case of positive refractive index, the gradient forces acting on a DNG particle may not reverse sign when the relative refractive index n goes from |n|>1 to |n|<1, thus revealing new and interesting trapping properties.
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http://dx.doi.org/10.1364/OE.18.024287 | DOI Listing |
Mar Environ Res
September 2025
Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan.
The northern South China Sea (SCS) shelf and southern Taiwan Strait (TS) are dynamic marginal seas influenced by both freshwater discharge from the Pearl River and seasonal coastal upwelling. These interacting hydrological forces shape ecological gradients that affect marine planktonic communities. Planktonic foraminiferal assemblages were analyzed from plankton tow and surface sediment samples collected during three cruises (2018, 2020, and 2022) along a ∼1000 km transect extending from the Pearl River estuary to the southern TS.
View Article and Find Full Text PDFEur J Cell Biol
September 2025
The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China. Electronic address:
Cell migration toward stiffer or softer environments (durotaxis) underlies processes from development to cancer metastasis, yet the underlying mechanism and its universality remain unclear. To resolve this, we investigated how traction forces and directional persistence dictate cell migration along stiffness gradients. We utilized tunable PEG hydrogels with stiffness gradients of 1-16 kPa and perturbed contractility (blebbistatin, oligomycin), and adhesion (vinculin mutants), in cancer cells exhibiting opposing durotactic biases.
View Article and Find Full Text PDFChemphyschem
September 2025
Department of Computer Science, Institute of Technology, Resource and Energy-efficient Engineering (TREE), Bonn-Rhein-Sieg University of Applied Sciences, 53757, Sankt Augustin, Germany.
Molecular modeling plays a vital role in many scientific fields, ranging from material science to drug design. To predict and investigate the properties of those systems, a suitable force field (FF) is required. Improving the accuracy or expanding the applicability of the FFs is an ongoing process, referred to as force-field parameter (FFParam) optimization.
View Article and Find Full Text PDFChaos
September 2025
CeBio y Departamento de Ciencias Básicas, Universidad Nacional del Noroeste de la Provincia de Buenos Aires (UNNOBA), CONICET, Roque Saenz Peña 456, Junin B6000, Argentina and Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, Rio de Janeiro 22290-180, RJ, Brazil.
Studies regarding physical phenomena described by nonlinear Fokker-Planck equations usually consider the case where the drift forces acting on the physical system under investigation are derived from the gradient of a potential function. In the present manuscript, we investigate nonlinear Fokker-Planck equations, where the drift field has a component that is derived from the gradient of an asymmetric potential and another that corresponds to a nongradient force term. We consider the specific case of a two-dimensional, nonlinear Fokker-Planck equation where the drift field is obtained from an anisotropic, harmonic potential, besides the nongradient term.
View Article and Find Full Text PDFBiology (Basel)
August 2025
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China.
Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are promising molecular biomarkers widely applied in paleoenvironmental reconstructions, including temperature and pH. However, knowledge of the microorganisms responsible for brGDGT production in marine environments remains limited, which constrains the further development and application of brGDGT-based proxies for reconstructing past marine conditions. In this study, both 'living' intact polar lipid-derived brGDGTs (IPL-brGDGTs) and 'fossil' core brGDGTs (CL-brGDGTs), together with bacterial community compositions, were analysed in multiple sediment cores collected along a nearshore-to-offshore transect in the East China Sea (ECS).
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