Impact of Slope Inclination on Salt Accumulation Due to Bare Soil Evaporation

While studies on salt precipitation over porous media due to evaporation have typically focused on horizontal and flat evaporating surface conditions, in reality, many evaporating surfaces are far from horizontal. In natural systems, agricultural environments, manmade structures and many other setups, evaporation from inclined surfaces is very common. Herein, the nature of solute transport and salt precipitation on inclined surfaces is discussed, and field measurements and laboratory experiments shed new light on the complex processes of salt dynamics over inclined, evaporating surfaces. Inclination of the evaporating surface was found to affect the location of the salt precipitation and the degree of salinity along the slope. For slopes of low-inclination, salt precipitation was uniform along the slope; as inclination increased, the lower parts of the slope remained relatively free of salt, while salt precipitation occurred in its upper parts. This was explained by a conceptual model suggesting that changes in slope inclination result in different pressure-head gradients along the slope, leading to different flow paths and velocities of the capillary water parallel to the evaporation front. Consequently, different solute-transport processes develop over slopes with different inclinations

In-situ monitoring of additives during CO2 gas hydrate formation

Research activities on the reduction of carbon dioxide emissions via effective carbon capture and storage (CCS) techniques are steadily increasing with the concept of storing CO2 as hydrates among the most prominently discussed strategies. The present study utilizes mid- infrared (MIR) fiberoptic evanescent field sensing techniques as a promising in-situ monitoring tool for investigating molecular changes occurring during CO2 hydrate formation. The identification and evaluation of characteristic IR absorption features associated with additive molecules (here, THF and SDS) and their changes during hydrate formation were pronounced via studies in D2O next to H2O as the hydrate forming matrix. By correlating IR-spectroscopic data with continuously recorded pressure and temperature traces, hypotheses on the involvement and promoting effect of such additives during carbon dioxide gas hydrate formation were experimentally consolidated

Toward the Required Detection Limits for Volatile Organic Constituents in Marine Environments with Infrared Evanescent Field Chemical Sensors

A portable sensor system for the simultaneous detection of multiple environmentally relevant volatile organic compounds (VOCs) in real seawater based on Fourier transform infrared fiber-optic evanescent wave spectroscopy (FT-IR-FEWS) was developed. A cylindrical silver halide (AgX) fiber with an ethylene/propylene copolymer (E/P-co) coated flattened segment was used as an active optical transducer. The polymer membrane enriches the hydrophobic analytes, while water is effectively excluded from the penetration depth of the evanescent field. Determination of multicomponent mixtures (i.e., 10 VOCs in real-world seawater samples) collected in Arcachon Bay, France revealed a high accuracy and reproducibility with detection limits down to 560 ppb. The measurement showed no significant influence from changing water conditions (e.g., salinity, turbidity, and temperature or other interfering substances). The time constants for 90% saturation of the polymer ranged from 20 to 60 min. The sensor system is capable of being transported for on-site monitoring of environmental pollutants in aqueous matrices with efficient long-term stability, thus showing great potential to be utilized as an early warning system

Infrared Spectroscopy for Monitoring Gas Hydrates in Aqueous Solution

The presented work describes first principles for monitoring gas hydrate formation and dissociation in solution by evaluating state-responsive IR absorption features of water with fiberoptic evanescent field spectroscopy. In addition, a first order linear functional relationship has been derived according to Lambert Beer’s law, which enables quantification of percentage gas hydrate within the volume of water directly probed via the evanescent field. Moreover, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components, thereby establishing evanescent field sensing strategies as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments.Non UBCUnreviewe

CO(2) Laser Fascia to Dura Soldering for Pig Dural Defect Reconstruction

Background and objectives: The purposes of this study were to demonstrate that laser soldering is safe and effective for tissue bonding in dural reconstruction and to compare this new reconstruction technique to an established one. Study design: A temperature-controlled fiberoptic CO(2) laser system or fibrin glue were used for in vitro dural defect reconstruction in two groups of pigs. The CO(2) laser technique was also used for dural reconstruction in live pigs. Results: The burst pressure of the reconstructed dura by the laser system was significantly higher than that of fibrin glue (mean pressure 258.5 ± 117.3 cm H(2)O and 76.8 ± 47.2 cm H(2)O, respectively). There were no postoperative complications and no signs of thermal damage to the dura, fascia, or underlying tissue on histological analysis following the in vivo CO(2) laser experiments. Conclusions: Temperature-controlled laser soldering is an effective technique for dural repair. It creates a strong tissue bonding with no thermal damage to the tissue. The burst pressure of the reconstructed dura done with laser soldering is significantly higher than that of fibrin glue

Laser tissue soldering of the gastrointestinal tract: A systematic review

Background: Laser Tissue Soldering (LTS) is a promising tissue bonding technique in which a solder is applied between the tissues and then irradiated by laser, causing it to solidify and form links with the tissue. Methods: A comprehensive systematic review summarizing the state of research of LTS in the gastrointestinal tract. Results: Most studies were conducted on large animal tissues, using liquid proteinaceous solder, and irradiated by a continuous wave laser at 808 nm. LTS can provide better sealing and burst pressure than conventional methods. The application of LTS on top of or in addition to sutures showed an impressive increase in burst pressures. LTS may decrease the inflammatory and foreign body reaction caused by sutures. Conclusions: LTS has strong potential to be applied in a clinical setting in leak prevention and in closure of gastrointestinal structures as an adjunct or additional anastomotic technology, decreasing leak rates, morbidity, and mortality

Single mode mid-infrared silver halide asymmetric flat waveguide obtained from crystal extrusion

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