Sorptive and geotechnical characteristics of kaolinite

The sorption/desorption behavior of phenol and chlorobenzene as well as their influence on geotechnical characteristics of kaolinite were studied. The results reveal that the sorption process follows closely with the Freundlich adsorption isotherm whereas the sorption/desorption ratio depends upon the characteristics of organic compounds. A series of geotechnical properties tests was also undertaken after achieving equilibrium at different concentrations of organic compounds. It was found that the parameters such as liquid limit, plastic limit, optimum moisture content, and dry density increase with an increasing-concentration of organic compounds. The relationship between the geotechnical, properties and sorption behavior of soils provides the information necessary in predicting the pollutant transport in the groundwater system. The variation of geotechnical properties due to sorption process is of paramount importance in construction engineering, such as the design of the liner in hazardous waste disposal site

Design, fabrication and characterization of monolithic embedded parylene microchannels in silicon substrate

This paper presents a novel channel fabrication technology of bulk-micromachined monolithic embedded polymer channels in silicon substrate. The fabrication process favorably obviates the need for sacrifical materials in surface-micromachined channels and wafer-bonding in conventional bulk-micromachined channels. Single-layer-deposited parylene C (poly-para-xylylene C) is selected as a structural material in the microfabricated channels/columns to conduct life science research. High pressure capacity can be obtained in these channels by the assistance of silicon substrate support to meet the needs of high-pressure loading conditions in microfluidic applications. The fabrication technology is completely compatible with further lithographic CMOS/MEMS processes, which enables the fabricated embedded structures to be totally integrated with on-chip micro/nano-sensors/actuators/structures for miniaturized lab-on-a-chip systems. An exemplary process was described to show the feasibility of combining bulk micromachining and surface micromachining techniques in process integration. Embedded channels in versatile cross-section profile designs have been fabricated and characterized to demonstrate their capabilities for various applications. A quasi-hemi-circular-shaped embedded parylene channel has been fabricated and verified to withstand inner pressure loadings higher than 1000 psi without failure for micro-high performance liquid chromatography (µHPLC) analysis. Fabrication of a high-aspect-ratio (internal channel height/internal channel width, greater than 20) quasi-rectangular-shaped embedded parylene channel has also been presented and characterized. Its implementation in a single-mask spiral parylene column longer than 1.1 m in a 3.3 mm × 3.3 mm square size on a chip has been demonstrated for prospective micro-gas chromatography (µGC) and high-density, high-efficiency separations. This proposed monolithic embedded channel technology can be extensively implemented to fabricate microchannels/columns in high-pressure microfludics and high-performance/high-throughput chip-based micro total analysis systems (µTAS)

Parylene-strengthened thermal isolation technology for microfluidic system-on-chip applications

Here we reported a novel technology using parylene-cross-linking structure to achieve on-chip air-gap thermal isolation for microfluidic system-on-chip (SOC) applications. Two applications based on this technology, on-chip continuous-flow polymerase chain reaction (PCR) and on-chip temperature gradient liquid chromatography (LC) were successfully demonstrated. Device thermal performance in each example was characterized. Results showed that our technology not only provides excellent on-chip thermal isolation but also its simplicity of integration with other on-chip components makes versatile microfluidic SOC applications feasible

Yield strength of thin-film parylene-C

For the first time, the yield strength of thin-film parylene-c is measured from membrane load-deflection experiments and surface profile analysis. To do so, the onset pressure which causes plastic deformation of the membrane is first experimentally measured. Then a new 2-step displacement model, together with the energy minimization technique, is developed to convert the onset pressure to the yield strength on the pre-stressed parylene membrane under a uniform pressure loading. The results depict a Yield Strength of 59 MPa (or 0.012 of strain) for thin-film parylene-c in comparison to 55 MPa reported by parylene vendor (measured from large samples). To double check with the result, the balloon model is further used to compare with the stress value from our model at the center of parylene membranes and good agreements are obtained

Resonance-induced sensitivity enhancement method for conductivity sensors

Methods and systems for improving the sensitivity of a variety of conductivity sensing devices, in particular capacitively-coupled contactless conductivity detectors. A parallel inductor is added to the conductivity sensor. The sensor with the parallel inductor is operated at a resonant frequency of the equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the conductance (and possibly a series resistance) is substantially removed from the equivalent circuit, leaving a purely resistive impedance. An appreciably higher sensor sensitivity results. Experimental verification shows that sensitivity improvements of the order of 10,000-fold are possible. Examples of detecting particulates with high precision by application of the apparatus and methods of operation are described

Nanometer gaps by feedback-controlled electromigration

Nanometer-sized gap (or nanogap) is one of the most fundamental devices in the nanotechnology field. Park et. al., first proposed the open-circuit electromigration method to fabricate nanogaps, but the process is only repeatable if Au film is thinner than 20 nm. To overcome these drawbacks, we develop the feedback-controlled electromigration process and find that not only repeatable nanogaps can be created in thicker film (up to 120 nm or thicker in our experiments), but superior gap size control and topology are obtained. Moreover, we develop two new approaches to make free-standing nanogaps. The tunneling current between the nanogap electrodes was used to demonstrate a sensitive pressure and/or temperature sensor. Finally, we also develop a simple thermal-expansion method to measure the gap size without needing delicate instrument

Association algorithm to mine the rules that govern enzyme definition and to classify protein sequences

BACKGROUND: The number of sequences compiled in many genome projects is growing exponentially, but most of them have not been characterized experimentally. An automatic annotation scheme must be in an urgent need to reduce the gap between the amount of new sequences produced and reliable functional annotation. This work proposes rules for automatically classifying the fungus genes. The approach involves elucidating the enzyme classifying rule that is hidden in UniProt protein knowledgebase and then applying it for classification. The association algorithm, Apriori, is utilized to mine the relationship between the enzyme class and significant InterPro entries. The candidate rules are evaluated for their classificatory capacity. RESULTS: There were five datasets collected from the Swiss-Prot for establishing the annotation rules. These were treated as the training sets. The TrEMBL entries were treated as the testing set. A correct enzyme classification rate of 70% was obtained for the prokaryote datasets and a similar rate of about 80% was obtained for the eukaryote datasets. The fungus training dataset which lacks an enzyme class description was also used to evaluate the fungus candidate rules. A total of 88 out of 5085 test entries were matched with the fungus rule set. These were otherwise poorly annotated using their functional descriptions. CONCLUSION: The feasibility of using the method presented here to classify enzyme classes based on the enzyme domain rules is evident. The rules may be also employed by the protein annotators in manual annotation or implemented in an automatic annotation flowchart

Plasma levels in sepsis patients of annexin A1, lipoxin A4, macrophage inflammatory protein-3a, and neutrophil gelatinase-associated lipocalin

AbstractBackgroundThe relationship between the various cytokine responses that occur during sepsis remains controversial. Emerging evidence indicates that the proinflammatory and anti-inflammatory responses are regulated simultaneously from the beginning of sepsis. However, the roles of the novel anti-inflammatory mediators annexin (Anx)A1 and lipoxin (LX)A4 and the proinflammatory cytokines neutrophil gelatinase-associated lipocalin (NGAL) and macrophage inflammatory protein (MIP)-3a have been studied.MethodsIn this study, the plasma levels of AnxA1, LXA4, NGAL, MIP-3a, interleukin (IL)-8 and IL-6 in patients with sepsis were determined on admission to the intensive care unit. The patients were classified into survivors and non-survivors based on their outcome on day 28.ResultsAnxA1 and LXA4 levels were decreased in sepsis patients compared with control patients, whereas the levels of the proinflammatory cytokines MIP-3a, NGAL, IL-8, and IL-6 were elevated. Furthermore, a significantly higher level of MIP-3a was detected in nonsurviving patients compared with surviving patients (p < 0.05), whereas there were no significant differences between these two groups for the levels of the other mediators. Correlation analysis demonstrated that only NGAL level was closely correlated with the level of IL-6. Univariate analysis indicated that the levels of MIP-3a and IL-8 were independent factors associated with patient survival, but this was not confirmed by the multivariate analysis.ConclusionAnxA1 and LXA4 plasma levels were found to be decreased in sepsis patients, whereas the levels of MIP-3a and NGAL were found to be elevated. This warrants further study in order to determine the clinical implications of these changes

Parylene-strengthened thermal isolation technology for microfluidic system-on-chip applications

Here we reported a novel technology using parylene-cross-linking structure to achieve on-chip air-gap thermal isolation for microfluidic system-on-chip (SOC) applications. Two applications based on this technology, on-chip continuous-flow polymerase chain reaction (PCR) and on-chip temperature gradient liquid chromatography (LC) were successfully demonstrated. Device thermal performance in each example was characterized. Results showed that our technology not only provides excellent on-chip thermal isolation but also its simplicity of integration with other on-chip components makes versatile microfluidic SOC applications feasible