Oscillation death in coupled counter-rotating identical nonlinear oscillators

We study oscillatory and oscillation suppressed phases in coupled counter-rotating nonlinear oscillators. We demonstrate the existence of limit cycle, amplitude death, and oscillation death, and also clarify the Hopf, pitchfork, and infinite period bifurcations between them. Especially, the oscillation death is a new type of oscillation suppressions of which the inhomogeneous steady states are neutrally stable. We discuss the robust neutral stability of the oscillation death in non-conservative systems via the anti-PT-symmetric phase transitions at exceptional points in terms of non-Hermitian systems.Comment: 7 pages, 4 figure

Amplitude death in a ring of nonidentical nonlinear oscillators with unidirectional coupling

We study the collective behaviors in a ring of coupled nonidentical nonlinear oscillators with unidirectional coupling, of which natural frequencies are distributed in a random way. We find the amplitude death phenomena in the case of unidirectional couplings and discuss the differences between the cases of bidirectional and unidirectional couplings. There are three main differences; there exists neither partial amplitude death nor local clustering behavior but oblique line structure which represents directional signal flow on the spatio-temporal patterns in the unidirectional coupling case. The unidirectional coupling has the advantage of easily obtaining global amplitude death in a ring of coupled oscillators with randomly distributed natural frequency. Finally, we explain the results using the eigenvalue analysis of Jacobian matrix at the origin and also discuss the transition of dynamical behavior coming from connection structure as coupling strength increases.Comment: 14 pages, 11 figure

Recent Advances in Bioimaging for Cancer Research

Molecular imaging techniques as well as nanoparticle applicable to molecular imaging are being explored to improve the cancer detection accuracy, which help to manage efficiently at the early stage. Among the various imaging technologies, optical imaging is a highly sensitive detection technique that allows direct observation of specific molecular events, biological pathways, and disease processes in real time through imaging probes that emit light in a range of wavelengths. Recently, nanoparticles have provided significant progresses that can be simultaneously used for cancer diagnosis and therapy (cancer theranostics). Theranostics aims to provide “image-guided cancer therapy,” by integrating therapeutic and imaging agents in a single platform. In addition, molecular imaging techniques facilitate “image-guided surgery” enabling maximization of tumor excision and minimization of side effects. The optical signals generated by fluorescence nanoparticles offer the possibility to distinguish tumor sites and normal tissues during surgery by real-time guidance, thereby increasing the long-term patient survival. These techniques will considerably contribute to reducing cancer recurrence and developing more effective cures. In this chapter, we will introduce diverse research on nanomaterials-based optical imaging for effective cancer therapy

2-(3-Ethyl­sulfanyl-5-fluoro-1-benzofuran-2-yl)acetic acid

The title compound, C12H11FO3S, was prepared by alkaline hydrolysis of ethyl 2–(3–ethyl­sulfan­yl–5–fluoro–1–benzofuran–2–­yl) acetate. In the crystal structure, the carboxyl groups are involved in inter­molecular O—H⋯O hydrogen bonds, which link the mol­ecules into centrosymmetric dimers. These dimers are further packed into stacks along the b axis by aromatic π–π inter­actions between the furan ring and the benzene ring of neighbouring benzofuran ring systems [centroid–centroid distance = 3.684 (5) Å]

5-Fluoro-2-(4-fluoro­phen­yl)-3-methyl­sulfinyl-1-benzofuran

In the title compound, C15H10F2O2S, the O atom and the methyl group of the methyl­sulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment. The 4-fluoro­phenyl ring is rotated out of the benzofuran plane by a dihedral angle of 28.09 (3)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O and C—H⋯F hydrogen bonds

Methyl 2-(5-methyl-3-methyl­sulfinyl-1-benzofuran-2-yl)acetate

The title compound, C13H14O4S, was prepared by oxidation of methyl 2-(5-methyl-3-methyl­sulfanyl-1-benzofuran-2-yl)acetate with 3-chloro­peroxy­benzoic acid. The O atom and methyl group of the methyl­sulfinyl substituent lie on opposite sides of the plane of the benzofuran system. The crystal structure is stabilized by inter­molecular aromatic π–π inter­actions between the benzene rings of neighbouring mol­ecules, with a centroid–centroid separation of 3.841 (3) Å

5-Bromo-2-phenyl-3-phenyl­sulfinyl-1-benzofuran

In the title compound, C20H13BrO2S, the O atom and the phenyl group of the phenyl­sulfinyl substituent are located on opposite sides of the plane of the benzofuran system. The S-bound phenyl ring is almost perpendicular to this plane [80.35 (8)°]. The phenyl ring in the 2-position is twisted with respect to the benzofuran plane, making a dihedral angle of 16.0 (1)°

2-(3-Ethyl­sulfanyl-5-phenyl-1-benzofuran-2-yl)acetic acid

The title compound, C18H16O3S, crystallizes with two symmetry-independent mol­ecules in the asymmetric unit. The phenyl rings are rotated out of the benzofuran planes, making dihedral angles of 43.38 (7) and 56.13 (6)° in the two mol­ecules. The carboxyl groups are involved in inversion-related inter­molecular O—H⋯O hydrogen bonds, which link the mol­ecules into centrosymmetric dimers. These dimers are further packed into stacks along the b axis by weak non-classical inter­molecular C—H⋯O hydrogen bonds. The crystal structure also exhibits inter­molecular C—H⋯π inter­actions, and two aromatic π–π inter­actions between the furan rings of neighbouring benzofuran systems; the centroid–centroid distances are 3.500 (3) and 3.605 (3) Å

Butyl 2-(5-bromo-3-methyl­sulfinyl-1-benzofuran-2-yl)acetate

In the title compound, C15H17BrO4S, the methyl­sulfinyl O atom and the methyl substituents lie on opposite sides of the plane through the benzofuran fragment. The crystal structure is stabilized by π–π inter­actions between the benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.698 (4) Å], and by C—H⋯π inter­actions between a methyl­ene H atom of the butyl group and the benzene ring of the benzofuran system. Additionally, the crystal structure exhibits weak inter­molecular C—H⋯O contacts. The butyl group is disordered over two positions, with site-occupancy factors, from refinement, of 0.720 (8) and 0.280 (8)