Optical nonlinearity and all-optical switching in pumpkin seed oil based on the spatial cross-phase modulation (SXPM) technique.

Nonlinear optics (NLO) and its applications have attracted increasing research interest in recent years owing to their contribution to the development of photonic technology. Accordingly, in this study, we investigated the NLO response of pumpkin seed oil using the spatial self-phase modulation (SSPM) method. Significant NLO characteristics have been experimentally studied at 405 nm and 532 nm continuous wave (CW) laser wavelengths, yielding second-order nonlinear refractive index ( n 2 , t h ) values of 6.54 × 10 - 5 cm 2 / W and 2.73 × 10 - 5 cm 2 / W , respectively. The findings suggest that the absorption of the material leads to higher optical nonlinearity at shorter wavelengths owing to higher thermal effects. Furthermore, we implemented a light-controlled-light system based on the spatial cross-phase modulation (SXPM) technique employing pumpkin seed oil. We successfully achieved all-optical switching by designing the 'ON' and 'OFF' modes. The results of this study can be considered for the future development of NLO applications. Moreover, our work investigates the potential of pumpkin seed oil for designing low-cost and high-efficiency NLO devices, and this contribution opens up a novel practical avenue for oil-based optical devices.

EUS-guided celiac plexus interventions in pancreatic cancer pain: An update and controversies for the endosonographer.

Patients with pancreatic cancer (pancreatic ductal adenocarcinoma [PDAC]) can develop abdominal pain that can be debilitating. Celiac plexus neurolysis (CPN) is a chemical ablation of the celiac plexus that can be used to treat pain caused by pancreatic malignancy. It can be performed by an anterior or posterior approach, and also can be done percutaneously or under guidance of transabdominal ultrasound, computed tomography, intra-operatively or most recently under linear endoscopic ultrasound (EUS) guidance (EUS-CPN). EUS is well-suited for identification of the celiac plexus due to the close proximity of the gastric wall to the origin of the celiac artery. EUS-CPN is now widely practiced, and different EUS approaches have been developed in order to improve the efficacy of this technique. Our objective is to review the use of EUS-CPN in PDAC, including a description of different techniques, review of its efficacy, predictors of pain response, and describe its limitations and safety, as well as new developments.

Applications of endoscopic ultrasound in pancreatic cancer.

Since the introduction of endoscopic ultrasound guided fine-needle aspiration (EUS-FNA), EUS has assumed a growing role in the diagnosis and management of pancreatic ductal adenocarcinoma (PDAC). The objective of this review is to discuss the various applications of EUS and EUS-FNA in PDAC. Initially, its use for detection, diagnosis and staging will be described. EUS and EUS-FNA are highly accurate modalities for detection and diagnosis of PDAC, this high accuracy, however, is decreased in specific situations particularly in the presence of chronic pancreatitis. Novel techniques such as contrast-enhanced EUS, elastography and analysis of DNA markers such as k-ras mutation analysis in FNA samples are in progress and might improve the accuracy of EUS in the detection of PDAC in this setting and will be addressed. EUS and EUS-FNA have recently evolved from a diagnostic to a therapeutic technique in the management of PDAC. Significant developments in therapeutic EUS have occurred including advances in celiac plexus interventions with direct injection of ganglia and improved pain control, EUS-guided fiducial and brachytherapy seed placement, fine-needle injection of intra-tumoral agents and advances in EUS-guided biliary drainage. The future role of EUS and EUS in management of PDAC is still emerging.

C6H and C6D: electronic spectra and Renner-Teller analysis.

Rotationally resolved spectra of the B(2)Π - X(2)Π 0(0)(0) electronic origin bands and 11(1)(1) µ(2)Σ-µ(2)Σ vibronic hot band transitions of both C(6)H and C(6)D have been recorded in direct absorption by cavity ring-down spectroscopy through a supersonically expanding planar plasma. For both origin and hot bands accurate spectroscopic parameters are derived from a precise rotational analysis. The origin band measurements extend earlier work and the 11(1)(1) µ(2)Σ-µ(2)Σ vibronic hot bands are discussed here for the first time. The Renner-Teller effect for the lowest bending mode ν(11) is analyzed, yielding the Renner parameters ε(11), vibrational frequencies ω(11), and the true spin-orbit coupling constants A(SO) for both (2)Π electronic states. From the Renner-Teller analysis and spectral intensity measurements as a function of plasma jet temperature, the excitation energy of the lowest-lying 11(1) µ(2)Σ vibronic state of C(6)H is determined to be (11.0 ± 0.8) cm(-1).

Structure determination of the nonlinear hydrocarbon chains C9H3 and C11H3 by deuterium labeling.

A systematic deuterium labeling experiment is presented that aims at an unambiguous determination of the geometrical ground state structure of the C(9)H(3) and C(11)H(3) hydrocarbon chains. Cavity ring-down spectroscopy and special plasma expansions constituting C/H, C/D, and C/H/D are used to record optical transitions of both species and their (partially) deuterated equivalents in the 19,000 cm(-1) region. The number of observed bands, the quantitative determination of isotopic shifts, and supporting calculations show that the observed C(9)H(3) and C(11)H(3) spectra originate from HC(4)(CH)C(4)H and HC(4)[C(C(2)H)]C(4)H species with C(2v) symmetry. This result illustrates the potential of deuterium labeling as a useful approach to characterize the molecular structure of nonlinear hydrocarbon chains.