10 research outputs found
Feasibility of using distributed chemical sensing for CO2 leakage monitoring
The feasibility study focused on the development of new fiber for distributed chemical sensing (DCS) that will allow direct detection of CO2 leakages in the environment. This is particularly important for monitoring well integrity for carbon capture and storage (CCS), to provide early warning for an incoming well failure and potential CO2 leaking through it. We proposed using optical spectroscopy in optical fiber for direct detection of CO2. The main approach is based on Raman interrogation within gas-filled Holey Fibers (HoFs), so that the location and concentration of the gases would be provided simultaneously via backscattering. Additionally, Infrared (IR) Absorption Spectroscopy could also be used, and the architecture would be more discrete since interleaving with standard solid core fibers and Fiber Bragg Grating (FBG) sections is required to enable reflection to the I/O controls. The possible Raman length or the IR numbers of sections would be defined based on signal to noise ratio. The optical spectroscopy methodology would overcome current roadblocks to CCS, as fiber optics will allow for CO2 (and other gases) detection in wells with direct in-situ measurements of concentration along with other important parameters such as temperature and pressure as the baseline of environment background.
We were able to assess commercially available IR/Raman hollow core fiber and demonstrated detection of CO2 through them in our controlled environment setups. We have also established the ability of drilling precisely with pulsed femtoseconds (fs)-lasers side holes to enable penetration of CO2 into the hollow core fiber and reduce diffusion rates. Open joint collars were also explored having a double functionality: splicing to solid core fiber critical for field deployment and creating gas ingress locations. Both diffusion-only and pressurized fiber systems have been constructed following numerical simulations in COMSOL based semi-hybrid optical /fluido-dynamics models. FBGs have been identified, procured, and characterized but not yet integrated. Along the work we leveraged internal modeling/design, photonics/laser characterization, optical fiber fabrication, and AM lab capabilities to design, develop and test in-house components or assemblies. Our results indicate the critical potential that the HoF would have in the direct detection of CO2 downhole
Editorial Nanomaterials for Optical Sensing and Sensors: Plasmonics, Raman, and Optofluidics
To date, environmental and healthcare problems have become the most important and challenging issues globally. Demands for fast and low-cost sensing methods and devices for environment monitoring This special issue contains 6 articles which cover the academic fields of environmental science, materials science, life science, nanotechnology, optics, physics, and chemistry. In the research article "Investigation of the Validity of the Universal Scaling Law on Linear Chains of Silver Nanoparticles," M. Alsawafta et al. examined (the generalization of) the universal scaling behavior for spherical silver nanoparticles arranged in finite linear chains (eight nanoparticles) and embedded in different host media. The results of simulation show that the plasmon ruler equation can be successfully extended to represent the fractional plasmon shift of many interacting nanoparticles. The decay length and the mount of the fractional shift of the silver linear chains strongly depend on the polarization state of the incident polarization. The LM exhibits a significant shift of the plasmon resonance (indicated by the value of ) as compared to that of the TM. This can be explained by the fact that the enhancement of the local field under parallel polarization is more pronounced. On the other hand, the decay of the TM shows a strong dependency on the dielectric function of the surrounding medium. It decays twice faster than the LM, as the host medium becomes denser. In the research article "Focused Ion Beam Assisted Interface Detection for Fabricating Functional Plasmonic Nanostructures," H. Wang et al. proposed the FIB-assisted interface detection and successfully carried out it using the sampleabsorbed current as the detection signal, and the patterning depth control for the plasmonic structure fabrication was achieved through controlling machining time or ion dose using the EPM. Material-dependent currents were measured through the EPM signal curves, and the quantitative models for the sample-absorbed currents and the ion beam current were also developed. In the research article "Immobilization Techniques and Integrated Signal Enhancement for POC Nanocolor Microfluidic Devices," M. Schlauf et al. reported the development of a silver enhancement technology that operates even in the presence of high chloride concentrations as it may be encountered in biologic samples. The silver enhancement reagents may be integrated into the microfluidic assay platform to be released upon sample addition. Hereby a highly sensitive onestep-assay can be realized. M. Schlauf et al. also demonstrated that adsorptive immobilization via a cationic polymeric interlayer is a competitive and fast technique for the binding of the capture protein streptavidin onto planar SiO 2 -surfaces such as REA biochips. In the research article "Investigating the Fabrication Imperfections of Plasmonic Nanohole Arrays and its Effect on the Optical Transmission Spectra," A. M. Mahros et al. investigated the extraordinary optical transmission spectra of thin gold films perforated with imperfect nano hole arrays using the finite difference time domain (FDTD) method. Exponential shapes for the nanohole sidewalls are used. The investigation of transmission spectra of imperfect nanohole arrays has not previously been demonstrated. It was found that the asymmetry between the two openings of the circular nanoholes or bending to their sidewalls strongly modifies both of the intensity and resonance positions of the transmission spectra. Furthermore, the results of this study assist in explaining the technicality of extraordinary optical transmission phenomenon and why some experimental results on transmission differ from those expected. In the research article "FRET-Based Detection of Enzymatic Reaction of Botulinum on Microfluidic Device," Y. M. Bae et al. implemented a microfluidic device to detect the enzymatic reaction of botulinum toxin A (BTA) using Förster resonance energy transfer (FRET). The microfluidic device comprised a main channel having two loading zones, a reaction chamber, and a side channel perpendicular to the main channel. The reaction chamber defined by weir in the main channel was packed with microbeads. The movement of the peptide substrate and the BTA in the microfluidic device was controlled by electrophoresis, and the enzymatic reaction of the BTA was detected through the changes of the fluorescence intensity in the reaction chamber. As a result, it was observed that the enzymatic reaction was affected by the electric voltage applied for the movement of the BTA and the peptide and improved by packing the microbeads in the reaction chamber. The microfluidic device provides with the tool to investigate the proteolysis of the substrate by the BTA. In the research article "Molecular Logic Computation with Debugging Method," X. Liu et al. considered constructing full adder and serial binary adder, using the new concept of seesaw gate. The simulation of the full add preformed properly as designed; however, unexpected exception is noted in the simulation of the serial binary adder. To identify and address the exception, they propose a new method for debugging the molecular circuit. The main idea for this method is to add fan-outs to monitor the circuit in a reverse stepwise manner. These fan-outs are fluorescent signals that can obtain the real-time concentration of the target molecule. By analyzing the monitoring result, the exception can be identified and located. In this paper, examples of XOR and serial binary adder circuits are described to prove the practicability and validity of the molecular circuit debugging method
Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study
: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (pâ=â0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (pâ=â0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (pâ=â0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (pâ=â0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (pâ=â0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (pâ=â0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (pâ=â0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (pâ<â0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (pâ=â0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (pâ=â0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)
Fabrication of suspended dielectric mirror structures via xenon difluoride etching of an amorphous germanium sacrificial layer
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Plasmon resonant cavities in vertical nanowire arrays
We investigate tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides. Resonances are observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors over 103 are possible due to plasmon focusing in the inter-wire space