An integrated laser Raman optical sensor for fast detection of nitrogen and oxygen in a cryogenic mixture

An integrated fiber optic Raman sensor was designed for real-time, nonintrusive detection of liquid nitrogen (LN(2)) in liquid oxygen (LO(2)) at high pressures and high flow rates. This was intended to monitor the quality of LO(2) in oxidizer feed lines during the ground testing of rocket engines. Various issues related to optical diagnosis of cryogenic fluids (LN(2)/LO(2)) in supercritical environment of rocket engine test facility, such as fluorescence from impurity in optical window of feed line, signal-noise ratio, and fast data acquisition time, etc., are well addressed. The integrated sensor employed a frequency doubled 532-nm continuous wave Nd:YAG laser as an excitation light source. The other optical components included were InPhotonics Raman probes, spectrometers, and photomultiplier tubes (PMTs). The spectrometer was used to collect the Raman spectrum of LN(2) and LO(2). The PMT detection unit was integrated with home-built LABVIEW software for fast monitoring of concentration ratios LN(2) and LO(2). Prior to designing an integrated sensor system, its optical components were also tested with gaseous nitrogen (GN(2)) and oxygen (GO(2)).     

Hydrothermal synthesis of hydrated vanadium oxide nanobelts using poly (ethylene oxide) as a template

With the aim of obtaining nanodevices as batteries, sensors and fuel cells, we prepared V₂O₅ and V₃O₇·H₂O nanobelts by a simple hydrothermal process using poly (ethylene oxide) (PEO) as a template. The yielding percentage of the nanomaterial is less in polymer-free V₂O₅ nanobelts and material size is also big. It is apparent that PEO used V₃O₇·H₂O form a continuous and relatively homogeneous matrix with a clearly 1–5 μm long and 50–150 nm diameter nanobelts morphology. The SEM micrographs suggest that there is no bulk deposition of polymer on the surface of the nano-crystallites. Strong interaction between the vanadyl group and the polymer during the formation process has been identified by the shifts of the vanadyl vibration peaks. The CV curve of the electrode made of the V₃O₇·H₂O nanobelts have higher current densities than the CV curve of the electrode made of V₂O₅ nanobelts.     

Synthesis and characterization of PANI nanostructures for supercapacitors and photoluminescence

Polyaniline structures were synthesized through a chemical method using citric acid and oxalic acid as carriers and 5???m size ??-alumina particles as a template. The obtained nano-size pristine products were characterized using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, optical absorption spectroscopy, photoluminescence spectroscopy and cyclic voltammetry (CV). Nanofibrous PANI was obtained with oxalic acid, nanoparticles with oxalic acid and ??-alumina, net-like nanostructures with citric acid and spherical nanoparticles with citric acid and ??-alumina. The high intensity photoluminescence of PANI prepared with oxalic acid as a carrier is possibly due to greater chances of exciton formation resulting from increased ??-electron mobility. Electrochemical studies of PANI electrodes in 2.0?M H₂SO₄ were carried out at various scan rates. The CVs showed rectangular shape with added pronounced oxidation and reduction peaks.     

First Demonstration of Gold Nanorods‐Mediated Photodynamic Therapeutic Destruction of Tumors via Near Infra‐Red Light Activation

Previously, a large volume of papers reports that gold nanorods (Au NRs) are able to effectively kill cancer cells upon high laser doses (usually 808 nm, 1–48 W/cm²) irradiation, leading to hyperthermia‐induced destruction of cancer cells, i.e, photothermal therapy (PTT) effects. Combination of Au NRs‐mediated PTT and organic photosensitizers‐mediated photodynamic therapy (PDT) were also reported to achieve synergistic PTT and PDT effects on killing cancer cells. Herein, we demonstrate for the first time that Au NRs alone can sensitize formation of singlet oxygen (¹O₂) and exert dramatic PDT effects on complete destrcution of tumors in mice under very low LED/laser doses of single photon NIR (915 nm, <130 mW/cm²) light excitation. By changing the NIR light excitation wavelengths, Au NRs‐mediated phototherapeutic effects can be switched from PDT to PTT or combination of both. Both PDT and PTT effects were confirmed by measurements of reactive oxygen species (ROS) and heat shock protein (HSP 70), singlet oxygen sensor green (SOSG) sensing, and sodium azide quenching in cellular experiments. In vivo mice experiments further show that the PDT effect via irradiation of Au NRs by 915 nm can destruct the B16F0 melanoma tumor in mice far more effectively than doxorubicin (a clinically used anti‐cancer drug) as well as the PTT effect (via irradiation of Au NRs by 780 nm light). In addition, we show that Au NRs can emit single photon‐induced fluorescence to illustrate their in vivo locations/distribution.     

Lewis acid–base properties of cellulose acetate phthalate‐polycaprolactonediol blend by inverse gas chromatography

The net retention volumes, V_N, of n‐alkanes and five polar probes are determined on cellulose acetate phthalate–polycaprolactonediol blend column by inverse gas chromatography in the temperature range 323.15–363.15 K. The dispersive surface energy, $\gamma _{\bf S}^{\bf d}$ , of the blend has been calculated using the V_N values of n‐alkanes and the $\gamma _{\bf S}^{\bf d}$ at 333.15 K is 12.6 mJ/m². The $\gamma _{\bf S}^{\bf d}$ values are decreasing linearly with increase of temperature. The V_N values of the five polar solutes are used to calculate the specific component of the enthalpy of adsorption, ${\Delta }{H}_{\bf a}^{\bf S}$ . The Lewis acid–base parameters, K_a and K_b, are derived using ${\bf \Delta }{H}_{\bf a}^{\bf S}$ values and are found to be 0.019 and 0.403, respectively. The K_a and K_b values indicate that the blend surface contain more basic sites and interact strongly with the acidic probes. The acid–base parameters have been used to analyze the preferential interaction of the solid surface with acidic and basic probes. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Unprecedented “All‐in‐One” Lanthanide‐Doped Mesoporous Silica Frameworks for Fluorescence/MR Imaging and Combination of NIR Light Triggered Chemo‐Photodynamic Therapy of Tumors

Designing a single multifunctional nanoparticle that can simultaneously impart both diagnostic and therapeutic functions is considered to be a long‐lasting hurdle for biomedical researchers. Conventionally, a multifunctional nanoparticle can be constructed by integrating organic dyes/magnetic nanoparticles to impart diagnostic functions and anticancer drugs/photosensitizers to achieve therapeutic outcomes. These multicomponents systems usually suffer from severe photobleaching problems and cannot be activated by near‐infrared (NIR) light. Here, it is demonstrated that all‐in‐one lanthanide‐doped mesoporous silica frameworks (EuGdOx@MSF) loaded with an anticancer drug, doxorubicin (DOX) can facilitate simultaneous bimodal magnetic resonance (MR) imaging with approximately twofold higher T₁‐MR contrast as compared to the commercial Gd(III)‐DTPA complex and fluorescence imaging with excellent photostability. Upon a very low dose (130 mW cm^?2) of NIR light (980 nm) irradiation, the EuGdOx@MSF not only can sensitize formation of singlet oxygen (¹O₂) by itself but also can phototrigger the release of the DOX payload effectively to exert combined chemo‐photodynamic therapeutic (PDT) effects and destroy solid tumors in mice completely. It is also discovered for the first time that the EuGdOx@MSF‐mediated PDT effect can suppress the level of the key drug resistant protein, i.e., p‐glycoprotein (p‐gp) and help alleviate the drug resistant problem commonly associated with many cancers.     

Design and analysis of full pitch winding and concentrated stator pole winding three-phase flux reversal machine for low speed application

The flux reversal machine (FRM) is a doubly-salient stator permanent magnet machine with flux linkage reversal in the stator concentrated winding. The existing machines at low speed, low power (2·4 kW, 300 rpm) range are not economical. FRM topology is best suited for this application. An attempt has been made to improve the power density of machine by introducing full pitch winding. Full pitch winding FRM (FPFRM) has higher power density than the conventional concentrated stator pole winding FRM (CSPFRM). Design and comparative analysis of FPFRM and CSPFRM are made. Both machines are designed for 88·58 Nm and 300 rpm. Design details of both machines are presented. Finite Element Method (FEM) analysis is carried out to evaluate and compare the performance of CSPFRM and FPFRM. Series capacitive compensation is provided for better voltage regulation of both machines.     

Fiber optic Raman sensor to monitor the concentration ratio of nitrogen and oxygen in a cryogenic mixture

A spontaneous Raman scattering optical fiber sensor was developed for a specific need of the National Aeronautics and Space Administration (NASA) for long-term detection and monitoring of the purity of liquid oxygen (LO(2)) in the oxidizer feed line during ground testing of rocket engines. The Raman peak intensity ratios for liquid nitrogen (LN(2)) and LO(2) with varied weight ratios (LN(2)/LO(2)) were analyzed for their applicability to impurity sensing. The study of the sensor performance with different excitation light sources has helped to design a miniaturized, cost-effective system for this application. The optimal system response time of this miniaturized sensor for LN(2)/LO(2) measurement was found to be in the range of a few seconds. It will need to be further reduced to the millisecond range for real-time, quantitative monitoring of the quality of cryogenic fluids in a harsh environment.