Free-electron lasers

Free-electron lasers (FELs) are lasers that use an electron beam from an accelerator to produce widely tunable, high power, ultrafast pulses of coherent radiation. FELs are today important sources of infrared and far-infrared radiation the world. Quasi-CW high-power FELs are also operational. FELs that operate on the self-amplified spontaneous emission principle are leading candidates for X-ray lasers and fourth-generation light sources. We discuss the physics, technology, advantages and applications of FELs, and explore the frontiers of X-ray and high-power FELs. We also present details of plans for a compact, ultrafast, terahertz free-electron laser in India

Spinster Homolog 2 (Spns2) Deficiency Causes Early Onset Progressive Hearing Loss

Spinster homolog 2 (Spns2) acts as a Sphingosine-1-phosphate (S1P) transporter in zebrafish and mice, regulating heart development and lymphocyte trafficking respectively. S1P is a biologically active lysophospholipid with multiple roles in signalling. The mechanism of action of Spns2 is still elusive in mammals. Here, we report that Spns2-deficient mice rapidly lost auditory sensitivity and endocochlear potential (EP) from 2 to 3 weeks old. We found progressive degeneration of sensory hair cells in the organ of Corti, but the earliest defect was a decline in the EP, suggesting that dysfunction of the lateral wall was the primary lesion. In the lateral wall of adult mutants, we observed structural changes of marginal cell boundaries and of strial capillaries, and reduced expression of several key proteins involved in the generation of the EP (Kcnj10, Kcnq1, Gjb2 and Gjb6), but these changes were likely to be secondary. Permeability of the boundaries of the stria vascularis and of the strial capillaries appeared normal. We also found focal retinal degeneration and anomalies of retinal capillaries together with anterior eye defects in Spns2 mutant mice. Targeted inactivation of Spns2 in red blood cells, platelets, or lymphatic or vascular endothelial cells did not affect hearing, but targeted ablation of Spns2 in the cochlea using a Sox10-Cre allele produced a similar auditory phenotype to the original mutation, suggesting that local Spns2 expression is critical for hearing in mammals. These findings indicate that Spns2 is required for normal maintenance of the EP and hence for normal auditory function, and support a role for S1P signalling in hearing

Nano-encapsulated triggered-release viscosity breaker

A method for the encapsulation and triggered-release of water-soluble or water-dispersible materials. The method comprises a) providing an amount of electrolyte having a charge, b) providing an amount of counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form aggregates, d) adding a compound to be encapsulated, and e) adding nanoparticles to the solution such that nanoparticles arrange themselves around the aggregates. Release of the encapsulated species is triggered by disassembly or deformation of the microcapsules though disruption of the charge interactions. This method is specifically useful for the controlled viscosity reduction of the fracturing fluids commonly utilized in the oil field

Prognostic utility of pretreatment neutrophil-lymphocyte ratio in survival outcomes in localized non-small cell lung cancer patients treated with stereotactic body radiotherapy: Selection of an ideal clinical cutoff point.

Background and purposeNeutrophil-lymphocyte ratio (NLR) has been associated with overall survival (OS) in non-small cell lung cancer (NSCLC). We aimed to assess the utility of NLR as a predictor of lung cancer-specific survival (LCS) and identify an optimal, pretreatment cutoff point in patients with localized NSCLC treated with stereotactic body radiotherapy (SBRT) within the Veterans Affairs' (VA) national database.Materials and methodsIn the VA database, we identified patients with biopsy-proven, clinical stage I NSCLC treated with SBRT between 2006 and 2015. Cutoff points for NLR were calculated using Contal/O'Quigley's and Cox Wald methods. Primary outcomes of OS, LCS, and non-lung cancer survival (NCS) were evaluated in Cox and Fine-Gray models.ResultsIn 389 patients, optimal NLR cutoff was identified as 4.0. In multivariable models, NLR > 4.0 was associated with decreased OS (HR 1.44, p = 0.01) and NCS (HR 1.68, p = 0.01) but not with LCS (HR 1.32, p = 0.09). In a subset analysis of 229 patients with pulmonary function tests, NLR > 4.0 remained associated with worse OS (HR 1.51, p = 0.02) and NCS (HR 2.18, p = 0.01) while the association with LCS decreased further (HR 1.22, p = 0.39).ConclusionNLR was associated with worse OS in patients with localized NSCLC treated with SBRT; however, NLR was only associated with NCS and not with LCS. Pretreatment NLR, with a cutoff of 4.0, offers potential as a marker of competing mortality risk which can aid in risk stratification in this typically frail and comorbid population. Further studies are needed to validate pretreatment NLR as a clinical tool in this setting

Prognostic utility of pretreatment neutrophil-lymphocyte ratio in survival outcomes in localized non-small cell lung cancer patients treated with stereotactic body radiotherapy: Selection of an ideal clinical cutoff point.

Background and purposeNeutrophil-lymphocyte ratio (NLR) has been associated with overall survival (OS) in non-small cell lung cancer (NSCLC). We aimed to assess the utility of NLR as a predictor of lung cancer-specific survival (LCS) and identify an optimal, pretreatment cutoff point in patients with localized NSCLC treated with stereotactic body radiotherapy (SBRT) within the Veterans Affairs' (VA) national database.Materials and methodsIn the VA database, we identified patients with biopsy-proven, clinical stage I NSCLC treated with SBRT between 2006 and 2015. Cutoff points for NLR were calculated using Contal/O'Quigley's and Cox Wald methods. Primary outcomes of OS, LCS, and non-lung cancer survival (NCS) were evaluated in Cox and Fine-Gray models.ResultsIn 389 patients, optimal NLR cutoff was identified as 4.0. In multivariable models, NLR > 4.0 was associated with decreased OS (HR 1.44, p = 0.01) and NCS (HR 1.68, p = 0.01) but not with LCS (HR 1.32, p = 0.09). In a subset analysis of 229 patients with pulmonary function tests, NLR > 4.0 remained associated with worse OS (HR 1.51, p = 0.02) and NCS (HR 2.18, p = 0.01) while the association with LCS decreased further (HR 1.22, p = 0.39).ConclusionNLR was associated with worse OS in patients with localized NSCLC treated with SBRT; however, NLR was only associated with NCS and not with LCS. Pretreatment NLR, with a cutoff of 4.0, offers potential as a marker of competing mortality risk which can aid in risk stratification in this typically frail and comorbid population. Further studies are needed to validate pretreatment NLR as a clinical tool in this setting

Spectral differences between enantiomeric and racemic Ru(bby)<SUB>3</SUB><SUP>2+</SUP> on layered clays: probable causes

The preferential self-annihilation(static and dynamic) of &#916;,&#923;-Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> over &#916; or &#923;-Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> is reported for aqueous dispersions of sodium hectorite lightly loaded with the Ru(II) chelate and subjected to pulsed laser excitation. by varying the loading level over a factor of ca.60, it is also shown that racemate emission falls off sharply with increased loading whereas emission from the enentiometric adsorbate remains more nearly constant. The decrease in luminescence yield of racemate with increased loading is mainly associated with an attenuation in the peak emission intensity, I(0), as found from time-resolved measurements. it is proposed, based on these studies, that clays offer both quenching and nonquenching sites for sorption and that &#916;,&#923;Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> prefers the latter at low loadings, the ions being clustered within such regions. Enantiometric Ru(bpy)<SUB>3</SUB><SUP>2+</SUP>, on the other hand, is more randomly distributed over the sites. the above model also permits rationalization of(i) observed changes inemission intensity with time,(ii) anomalies in the relative emission yields of Ru(bpy)<SUB>3</SUB><SUP>2+&#8727;</SUP> and Ru(phen)<SUB>3</SUB><SUP>2+</SUP>, and (iii) the effect of zn(phen)<SUB>3</SUB><SUP>2+</SUP> on emission. Finally, differences in binding modes of enantionmeric and racemic chelate forms also induce differences in the flocculation trends of dispersed clays, the effects being most prominent for freshly prepared ruthenium(II) montorillinite

Understanding the facile photooxidation of Ru (bpy)<SUB>3</SUB><SUP>2+</SUP> in strongly acidic aqueous solution containing dissolved oxygen

The previously observed facile photooxidation of Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> to Ru(bpy)<SUB>3</SUB><SUP>3+</SUP> in oxygenated solutions of 9 M H<SUB>2</SUB>SO<SUP>4</SUP> is further studied. A similar phenomenon was observed with Ru(phen)<SUB>3</SUB><SUP>2+</SUP> but not with Ru(bpy)<SUB>2</SUB>[bpy-(CO<SUB>2</SUB>H)<SUB>2</SUB>]<SUP>2+</SUP>. The reaction is strongly dependent on acid concentration, with a sharp change in the region of 2-7 M H<SUB>2</SUB>SO<SUB>4</SUB>. The quantum yield of Ru(bpy)<SUB>3</SUB><SUP>3+</SUP> formation in 9 M H<SUB>2</SUB>SO<SUB>4</SUB> is close to the quantum yield of steady-state luminescence quenching by O<SUB>2</SUB>. Photooxidation is accompanied by near-stoichiometric formation of H<SUB>2</SUB>O<SUB>2</SUB> as reduced product. Chromatographic, spectroscopic, electrochemical and optical rotation studies reveal that Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> survives the strongly acidic environment with little evidence of either any change in coordination sphere or ligand degradation, even after repeated cycles of photolytic oxidation followed by electrolytic reduction. The high quantum yield and selectivity of the reaction is ascribed to (i) predominance of the electron transfer quenching pathway over all others and (ii) highly efficient trapping of O<SUB>2</SUB>&#183;- by H<SUP>+</SUP> followed by rapid disproportionation to H<SUB>2</SUB>O<SUB>2</SUB> and O<SUB>2</SUB>. These are likely on account of the high ionic strength of the medium which favors the required shifts in the potentials of the O<SUB>2</SUB>/O<SUB>2</SUB>&#183;- and O<SUB>2</SUB>/H<SUB>2</SUB>O<SUB>2</SUB> couples. Upon storage of the photooxidized Ru(III) solution in dark, partial recovery of Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> occurs gradually. Studies with the electrooxidized complex over a range of acid concentrations indicate that Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> is regenerated by reaction of Ru(bpy)<SUB>3</SUB>3+ with H<SUB>2</SUB>O<SUB>2</SUB>. The reaction is promoted by increasing concentrations of [H<SUB>2</SUB>O<SUP>2</SUP>] and inhibited by [O<SUB>2</SUB>] and [H<SUP>+</SUP>]. The fraction of Ru(III) remaining after the reverse reaction is allowed to plateau in solutions of varying acid concentrations follows a similar trend to that found after attainment of steady state in the photooxidation reaction, although in all cases the forward reaction produces more Ru(III) than what remains in the reverse reaction. These observations are consistent with the following equation 2Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> + O<SUB>2</SUB> + 2H<SUP>+</SUP> &#8594;(h&#957;)/&#8592;(dark) 2Ru(bpy)<SUB>3</SUB><SUP>3+</SUP> + H<SUB>2</SUB>O<SUB>2</SUB> for which the equilibrium constant has been computed. Light helps overcome the activation barrier of the forward reaction by driving it via <SUP>&#x002A;</SUP>Ru(bpy)<SUB>3</SUB><SUP>2+</SUP>, and to the extent that the photooxidation is driven past the equilibrium, there is conversion of light energy in the form of long-lived chemical products. Spectroscopic evidence rules out any significant shift in the redox potential of Ru(bpy)<SUB>3</SUB><SUP>3+/2+</SUP>, suggesting thereby that H<SUB>2</SUB>O<SUB>2</SUB> is much more stable in the more strongly acidic medium and less capable of reducing Ru(bpy)<SUB>3</SUB><SUP>3+</SUP> unlike at higher pH

Risk of Pelvic Fracture With Radiation Therapy in Older Patients

PurposeOlder patients undergoing radiation therapy (RT) for pelvic malignancies are at increased risk for pelvic fracture, which is associated with significant morbidity and mortality. RT techniques such as brachytherapy or intensity modulated RT (IMRT) allow for more conformal dose distributions, but it is not known whether the risk for pelvic fracture varies by RT modality.Methods and materialsThis observational cohort study involved 28,354 patients ≥65 years old, treated with RT for pelvic malignancies. We evaluated the relative risk of pelvic fracture by type of RT when accounting for baseline factors. To test for nonspecific effects, we also evaluated risk of nonpelvic fractures in the same population.ResultsThe 5-year incidence of pelvic fractures was 12.7% (95% confidence interval [CI], 11.6%-13.8%), 11.8% (10.8%-12.8%), and 3.7% (3.4%-4.0%) for patients with gastrointestinal, gynecologic, and prostate cancer, respectively. On multivariable analysis, being treated with IMRT (hazard ratio, 0.85; 95% CI, 0.73-0.99) or brachytherapy therapy alone (hazard ratio, 0.43; 95% CI, 0.34-0.54) was associated with a reduced hazard for pelvic fractures compared with 3D conformal radiation therapy in female patients. In contrast, there was no association with RT modality and the hazard for nonpelvic fractures among females. There was no significant association between pelvic fractures and IMRT or brachytherapy for male patients. White race, advanced age, and higher comorbidity were associated with an increased hazard for pelvic fracture.ConclusionsIMRT and brachytherapy were associated with a reduced risk of pelvic fractures in older women undergoing RT for pelvic malignancies. Pelvic insufficiency fracture risk should be considered when treating with pelvic RT