Highly sensitive and specific detection of E. coli by a SERS nanobiosensor chip utilizing metallic nanosculptured thin films

A nanobiosensor chip, utilizing surface enhanced Raman spectroscopy (SERS) on nanosculptured thin films (nSTFs) of silver, was shown to detect Escherichia coli (E. coli) bacteria down to the concentration level of a single bacterium. The sensor utilizes highly enhanced plasmonic nSTFs of silver on a silicon platform for the enhancement of Raman bands as checked with adsorbed 4-aminothiophenol molecules. T-4 bacteriophages were immobilized on the aforementioned surface of the chip for the specific capture of target E. coli bacteria. To demonstrate that no significant non-specific immobilization of other bacteria occurs, three different, additional bacterial strains, Chromobacterium violaceum, Paracoccus denitrificans and Pseudomonas aeruginosa were used. Furthermore, experiments performed on an additional strain of E. coli to address the specificity and reusability of the sensor showed that the sensor operates for different strains of E. coli and is reusable. Time resolved phase contrast microscopy of the E. coli-T4 bacteriophage chip was performed to study its interaction with bacteria over time. Results showed that the present sensor performs a fast, accurate and stable detection of E. coli with ultra-small concentrations of bacteria down to the level of a single bacterium in 10 μl volume of the sample

Surface-plasmon-polariton wave propagation guided by a metal slab in a sculptured nematic thin film

Surface-plasmon-polariton~(SPP) wave propagation guided by a metal slab in a periodically nonhomogeneous sculptured nematic thin film~(SNTF) was studied theoretically. The morphologically significant planes of the SNTF on both sides of the metal slab could either be aligned or twisted with respect to each other. The canonical boundary-value problem was formulated, solved for SPP-wave propagation, and examined to determine the effect of slab thickness on the multiplicity and the spatial profiles of SPP waves. Decrease in slab thickness was found to result in more intense coupling of two metal/SNTF interfaces. But when the metal slab becomes thicker, the coupling between the two interfaces reduces and SPP waves localize to one of the two interfaces. The greater the coupling between the two metal/SNTF interfaces, the smaller is the phase speed.Comment: 17 page

Investigation the Activity of Pd Loading on Commercial Monolithic Catalyst in Automobile Exhaust Gases

Catalytic monolith reactors have numerous applications in industrial processes and as technical devices, so the focus is set specially on automotive catalytic converters. The present work aimed to study the experimental performance of monolith reactor on the oxidation and reduction of exhaust gas (NO, CO, and HC) which emitted from gasoline generator. Commercial and modified commercial ceramic monolith catalyst was used in the present work. The modified commercial catalyst was obtained by loaded Pd metal .A laboratory unit was constructed for this purpose where a versatile stainless steel monolith reactor of 0.02 m inside diameter and 0.2 m height was used.The catalytic performance of the catalysts was studied in the following operating conditions, in a border range of gas space velocity(17.69 – 44.23s-1), reaction temperature(373 – 673 K), bed length(0.075 – 0.15 m) and at atmospheric pressure and constant air/fuel ratio (14.6).The results show that the conversion of NO, CO and HC are slightly changed with the bed length . The conversion of exhaust gas reactant enhances in presence of water, increases with the increasing reaction temperature and decreases with increasing gas space velocity. Monolithic catalyst which loaded with 0.4% Pd gives high conversion compared with an commercial catalyst (unloaded) for the HC oxidation reaction more than CO oxidation and NO reduction

Switching dynamics of surface stabilized ferroelectric liquid crystal cells: effects of anchoring energy asymmetry

We study both theoretically and experimentally switching dynamics in surface stabilized ferroelectric liquid crystal cells with asymmetric boundary conditions. In these cells the bounding surfaces are treated differently to produce asymmetry in their anchoring properties. Our electro-optic measurements of the switching voltage thresholds that are determined by the peaks of the reversal polarization current reveal the frequency dependent shift of the hysteresis loop. We examine the predictions of the uniform dynamical model with the anchoring energy taken into account. It is found that the asymmetry effects are dominated by the polar contribution to the anchoring energy. Frequency dependence of the voltage thresholds is studied by analyzing the properties of time-periodic solutions to the dynamical equation (cycles). For this purpose, we apply the method that uses the parameterized half-period mappings for the approximate model and relate the cycles to the fixed points of the composition of two half-period mappings. The cycles are found to be unstable and can only be formed when the driving frequency is lower than its critical value. The polar anchoring parameter is estimated by making a comparison between the results of modelling and the experimental data for the shift vs frequency curve. For a double-well potential considered as a deformation of the Rapini-Papoular potential, the branch of stable cycles emerges in the low frequency region separated by the gap from the high frequency interval for unstable cycles.Comment: 35 pages, 15 figure

Pain and analgesic use associated with skeletal-related events in patients with advanced cancer and bone metastases

PURPOSE: Bone metastases secondary to solid tumors increase the risk of skeletal-related events (SREs), including the occurrence of pathological fracture (PF), radiation to bone (RB), surgery to bone (SB), and spinal cord compression (SCC). The aim of this study was to evaluate the impact of SREs on patients' pain, analgesic use, and pain interference with daily functioning. METHODS: Data were combined from patients with solid tumors and bone metastases who received denosumab or zoledronic acid across three identically designed phase 3 trials (N = 5543). Pain severity (worst pain) and pain interference were assessed using the Brief Pain Inventory at baseline and each monthly visit. Analgesic use was quantified using the Analgesic Quantification Algorithm. RESULTS: The proportion of patients with moderate/severe pain and strong opioid use generally increased in the 6 months preceding an SRE and remained elevated, while they remained relatively consistent over time in patients without an SRE. Regression analysis indicated that all SRE types were significantly associated with an increased risk of progression to moderate/severe pain and strong opioid use. PF, RB, and SCC were associated with significantly greater risk of pain interference overall. Results were similar for pain interference with emotional well-being. All SRE types were associated with significantly greater risk of pain interference with physical function. CONCLUSIONS: SREs are associated with increased pain and analgesic use in patients with bone metastases. Treatments that prevent SREs may decrease pain and the need for opioid analgesics and reduce the impact of pain on daily functioning

Pain and analgesic use associated with skeletal-related events in patients with advanced cancer and bone metastases

PURPOSE: Bone metastases secondary to solid tumors increase the risk of skeletal-related events (SREs), including the occurrence of pathological fracture (PF), radiation to bone (RB), surgery to bone (SB), and spinal cord compression (SCC). The aim of this study was to evaluate the impact of SREs on patients' pain, analgesic use, and pain interference with daily functioning. METHODS: Data were combined from patients with solid tumors and bone metastases who received denosumab or zoledronic acid across three identically designed phase 3 trials (N = 5543). Pain severity (worst pain) and pain interference were assessed using the Brief Pain Inventory at baseline and each monthly visit. Analgesic use was quantified using the Analgesic Quantification Algorithm. RESULTS: The proportion of patients with moderate/severe pain and strong opioid use generally increased in the 6 months preceding an SRE and remained elevated, while they remained relatively consistent over time in patients without an SRE. Regression analysis indicated that all SRE types were significantly associated with an increased risk of progression to moderate/severe pain and strong opioid use. PF, RB, and SCC were associated with significantly greater risk of pain interference overall. Results were similar for pain interference with emotional well-being. All SRE types were associated with significantly greater risk of pain interference with physical function. CONCLUSIONS: SREs are associated with increased pain and analgesic use in patients with bone metastases. Treatments that prevent SREs may decrease pain and the need for opioid analgesics and reduce the impact of pain on daily functioning

Field-Dependent Tilt and Birefringence of Electroclinic Liquid Crystals: Theory and Experiment

An unresolved issue in the theory of liquid crystals is the molecular basis of the electroclinic effect in the smectic-A phase. Recent x-ray scattering experiments suggest that, in a class of siloxane-containing liquid crystals, an electric field changes a state of disordered molecular tilt in random directions into a state of ordered tilt in one direction. To investigate this issue, we measure the optical tilt and birefringence of these liquid crystals as functions of field and temperature, and we develop a theory for the distribution of molecular orientations under a field. Comparison of theory and experiment confirms that these materials have a disordered distribution of molecular tilt directions that is aligned by an electric field, giving a large electroclinic effect. It also shows that the net dipole moment of a correlated volume of molecules, a key parameter in the theory, scales as a power law near the smectic-A--smectic-C transition.Comment: 18 pages, including 9 postscript figures, uses REVTeX 3.0 and epsf.st

Engineering hotspots in an ESP-LSP configuration for ultra-high SERS enhancement based sensors

The critical importance of inter-particle gap on SERS enhancement was established both theoretically and experimentally to achieve enhancement of 1010 in an ESP-LSP configuration. Highly sensitive detection of glycerin was presented as model sensing.NRF (Natl Research Foundation, S’pore)Published versio

SERS biosensor using metallic nano-sculptured thin films for the detection of endocrine disrupting compound biomarker vitellogenin

A biosensor chip is developed for the detection of a protein biomarker of endocrine disrupting compounds, vitellogenin (Vg) in aquatic environment. The sensor chip is fabricated by immobilizing anti-Vg antibody on 4-Aminothiophenol (4-ATP) coated nanosculptured thin films (nSTFs) of silver on Si substrates. The biosensor is based on the SERS of 4-ATP, enhanced by the Ag nSTFs. Before the fabrication of the sensor, the performance of the enhancement is optimized with respect to the porosity of nSTFs. Further, the biosensor is developed on the nSTF with optimized enhancement. The SERS signals are recorded from the sensor chip for varying concentrations of Vg. A control experiment is performed on another similar protein Fetuin to confirm the specificity of the sensor. The repeatability and reusability of the sensor, along with its shelf life are also checked. The limit of detection of the sensor is found to be 5 pg mL-1 of Vg in PBS within our experimental window. Apart from high sensitivity, specificity and reusability, the present sensor provides additional advantages of miniaturization, requirement of very small volumes of the analyte solution (15 μL) and fast response as compared to conventional techniques e.g., ELISA, as its response time is less than 3 minutes