ABSTRACT
We describe a broadband (12.5-30 nm) extreme ultraviolet (XUV) spectrograph, which is stigmatic throughout its operating range. The instrument employs a near-normal-incidence aperiodic Mo/Si multilayer mirror and a grazing-incidence plane varied line-space (VLS) grating. Strict stigmatism is fulfilled simultaneously at two wavelengths and the condition of practical stigmatism is fulfilled over two octaves in wavelength. The vertically space-resolved line spectra of multiple charge ions from laser plasma were recorded to demonstrate a spectral resolving power of 103 and a spatial resolution of ~26 µm, both figures corresponding to two detector pixels. The electron density was evaluated from the Stark broadening of the Balmer line Hß (135 Å) of C VI in the plasma excited by 0.5 J, 8 ns, 1.06 µm pulses.
ABSTRACT
Pancreatic cancer poorly responds to available drugs, and finding novel approaches to target this cancer type is of high significance. Here, based on a common property of pancreatic cancer cells to express somatostatin receptors (SSTR), we designed drug conjugates with novel somatostatin-derived cyclic peptides (SSTp) with broad selectivity towards SSTR types to facilitate drug targeting of the pancreatic cancer cells specifically. Uptake of our newly designed SSTps was facilitated by SSTRs expressed in the pancreatic cancers, including SSTR2, SSTR3, SSTR4 and SSTR5. Three major drugs were conjugated to our best SSTps that served as delivery vehicles, including Camptothecin (CPT), Combretastatin-4A (COMB) and Azatoxin (AZA). All designed drug conjugates demonstrated penetration to pancreatic cancer cell lines, and significant toxicity towards them. Furthermore, the drug conjugates specifically accumulated in tumors in the animal xenograft model, though some accumulation was also seen in kidney. Overall these findings lay the basis for development of novel drug series that could target the fatal pancreatic cancer.
Subject(s)
Antineoplastic Agents/chemical synthesis , Peptides, Cyclic/chemistry , Somatostatin/chemistry , Animals , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Camptothecin/chemistry , Cell Line, Tumor , Cell Survival/drug effects , Humans , Indoles/chemistry , Kidney/metabolism , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Peptides, Cyclic/chemical synthesis , Receptors, Somatostatin/antagonists & inhibitors , Receptors, Somatostatin/genetics , Receptors, Somatostatin/metabolism , Stilbenes/chemistry , Tissue Distribution , Xenograft Model Antitumor AssaysABSTRACT
Burst Intensification by Singularity Emitting Radiation (BISER) is proposed. Singularities in multi-stream flows of emitting media cause constructive interference of emitted travelling waves, forming extremely localized sources of bright coherent emission. Here we for the first time demonstrate this extreme localization of BISER by direct observation of nano-scale coherent x-ray sources in a laser plasma. The energy emitted into the spectral range from 60 to 100 eV is up to ~100 nJ, corresponding to ~1010 photons. Simulations reveal that these sources emit trains of attosecond x-ray pulses. Our findings establish a new class of bright laboratory sources of electromagnetic radiation. Furthermore, being applicable to travelling waves of any nature (e.g. electromagnetic, gravitational or acoustic), BISER provides a novel framework for creating new emitters and for interpreting observations in many fields of science.
ABSTRACT
We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving µJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.
ABSTRACT
Laser light reflection by a relativistically moving electron density modulation (flying mirror) in a wake wave generated in a plasma by a high intensity laser pulse is investigated experimentally. A counterpropagating laser pulse is reflected and upshifted in frequency with a multiplication factor of 37-66, corresponding to the extreme ultraviolet wavelength. The demonstrated flying mirror reflectivity (from 3 x 10(-6) to 2 x 10(-5), and from 1.3 x 10(-4) to 0.6 x 10(-3), for the photon number and pulse energy, respectively) is close to the theoretical estimate for the parameters of the experiment.
ABSTRACT
The RES-C grazing incidence XUV spectroheliograph has been developed in the P. N. Lebedev Physical Institute (FIAN) as a part of the CORONAS-I project. Its objective is to obtain images of the full Sun in monochromatic lines over the spectral range of 180210Å, which includes prominent emission from ions of Fe VIIIFe~XIII, O VI, and Fe XXIV. Here, we describe the optical scheme of the spectroheliograph, and show results of XUV testing of its individual component elements as well as of the complete assembled instrument. XUV measurements were made of the absolute diffraction efficiency and stray-light level for both holographic and mechanically ruled gratings, the spectral reflectivity of the multilayer-coated mirrors, the transmittance of the thin aluminum blocking filters, and the combined spectral efficiency of the whole instrument. The spectral and spatial resolutions of the spectroheliograph were measured by recording spectrally dispersed images of a laser plasma source in monochromatic lines of fluorine ions between 185200Å. For comparison, we also present spectral images of the Sun obtained with the spectroheliograph as flown on the CORONAS-I satellite mission.