Microspectroscopic SERS detection of interleukin-6 with rationally designed gold/silver nanoshells

Rationally designed gold/silver nanoshells (Au/Ag-NS) with plasmon resonances optimized for red laser excitation in order to minimize autofluorescence from clinical samples exhibit scattering cross-sections, which are ca. one order of magnitude larger compared with solid quasi-spherical gold nanoparticles (Au-NPs) of the same size. Hydrophilic stabilization and sterical accessibility for subsequent bioconjugation of Au/Ag-NS is achieved by coating their surface with a self-assembled monolayer (SAM) of rationally designed Raman reporter molecules comprising terminal mono- and tri-ethylene glycol (EG) spacers, respectively. The stability of the hydrophilically stabilized metal colloid was tested under different conditions. In contrast to metal colloids coated with a SAM without terminal EG spacers, the hydrophilically stabilized SERS particles do not aggregate under physiologically relevant conditions, i.e., buffer solutions with high ionic strength. Using these rationally designed SERS particles in conjunction with a microspectroscopic acquisition scheme, a sandwich immunoassay for the sensitive detection of interleukin-6 (IL-6) was developed. Several control experiments demonstrate the high specificity of the assay towards IL-6, with a lowest detectable concentration of ca. 1 pg mL -1. The signal strength of the Au/Ag-NS is at least one order of magnitude higher compared with hydrophilically stabilized, non-aggregated solid quasi-spherical Au-NPs of the same size. This journal i

Computational fluid dynamics simulation and experimental validation of heat transfer in liquid piston compressors

The liquid piston concept is suggested to improve the efficiency of compression and expansion steps in thermodynamic processes, due to near isothermal compression or expansion. Within the concept a liquid piston is utilized to compress or expand a gas, instead of a solid piston. The liquid piston has some advantages, like perfect sealing of low molecular gases, high efficiency and realization of discontinuously piston motion. The good sealing characteristics arise from the perfect adaption of a liquid to an arbitrarily shaped wall. In the same way the high efficiency stems from intensive heat transfer between the gas and its surroundings during the process, due to a low volume to surface ratio. In order to define design guidelines for a liquid piston compressor or expander prototype, extensive knowledge of the thermodynamic processes within the gas chamber are necessary. Therefore the heat transfer of a compression process with helium gas in tube bundle chamber geometry has been studied. The heat transfer is analyzed by a computational fluid dynamics (CFD) model, considering one tube with 38 mm in internal diameter and 2000 mm in length, at different compression times from 12 s to 60 s. The gas is compressed to 10 MPa, starting at 5 MPa and ambient temperatures about 293 K, with different pressure ratios around 2. In order to verify the computational model, the results are compared to measured experimental data from a testing device. The device compression chamber is equipped with a pressure transducer and several thermocouples in radial and vertical direction. The gas used in experiment is helium, while for the liquid piston hydraulic oil is applied. The results showed a good match in local temperature and pressure between the computational model and the experimental data. Based on these results the heat transfer coefficient was calculated for the different compression times, showing values from 153 W/m²K up to 252 W/m²K. These measures are leading to near isothermal compression, increasing the efficiency of any thermodynamic cycle with gas compression, the liquid piston concept is included. The liquid piston concept has several benefits due to compression and expansion process components, which makes it interesting for the Stirling cycle. Further investigations also will be done in using the liquid piston concept, respectively isotherm compression, in refrigeration cycles.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Femtogram detection of cytokines in a direct dot-blot assay using SERS microspectroscopy and hydrophilically stabilized Au-Ag nanoshells

Rapid parallel detection of two cytokines (IL-6 and IL-8) with femtogram sensitivity in a simple direct dot-blot assay is demonstrated. The microspectroscopic SERS acquisition scheme employs rationally designed, hydrophilically stabilized Au-Ag nanoshells as SERS labels, which are optimized for signal enhancement upon red laser excitation

Guidelines To Maximize Reliability And Minimize Risk In Plants Using High Pressure Process Diaphragm Pumps

Lecturepg. 7

Diaphragm Development Trends For Safe Leak Free Reciprocating Process Pumps

Tutorialpg. 207The application of diaphragm pumps for metering and conveying the fluids are continuously expanding because they provide zero-leakage, can run dry, have superior efficiency, offer high reliability, maximize safety and minimize maintenance. However, end users should develop an understanding of the functional details involved and the necessity of a systems approach when installing and operating these pumps. The diaphragm design and the various influences on endurance and reliability are evaluated. Among others: material selection, the diaphragm motive system, the pump head/diaphragm, and installation/diaphragm interactions, diaphragm clamping, sandwich diaphragm design, computation of stresses and fatigue for both metal and PTFE diaphragm. Objectives or further optimization of diaphragm designs and comments about economy, performance and reliability close the discussion

Dynamic Monitoring For Early Failure Diagnosis And Modern Techniques For Design Of Positive Displacement Pumping Systems

Lecturepg. 103Competitive marketplace pressures for higher quality products with consistent material properties at lower cost are changing the face of chemical process manufacturing facilities. More frequently today, critical equipment is installed in unspared service with minimal onsite spare parts, yet demanded to operate reliably without defects for greater periods of time. An important component that helps make this possible is the emergence of increasingly more powerful and lower cost online condition monitoring systems for early failure diagnosis. These systems have moved into the relatively inhospitable chemical plant environment, capability that until recently was largely the domain of the engineering laboratory. High-frequency dynamic measurement, with automated statistical and mathematical post-processing, is now available live, remotely, via the Internet across the globe. This paper examines this technology in applications with several high-pressure process diaphragm pumping systems. Many key learnings are explored along with advances in system design that have been developed as a result of application of these techniques. Numerous real examples illustrate how to recognize improper precharge of gas-padded pulsation dampeners, and even correct while operating. Examples include diagnosis of excess internal leakage, with means to trace further to check valves or other pump internal sources. Fluid property changes, pulsation, and other problems can be diagnosed remotely. Shared in considerable experience gained over the past two years during continuous monitoring on both laboratory and real plant systems. This enables precise knowledge of trends in behavior and root causes so corrective action can be planned, parts and expertise made available, and downtime eliminated or minimized