CF Concentrations Research Articles

A Sustainable and Cost‐Effective Bioadsorbent for the Removal of Allura Red from Contaminated Water

AbstractFood grade dyes pose severe health hazards when consumed in excessive amounts or enter body via contaminated water. Despite its harmful effects, Allura Red (AR) is very less explored dye for its removal, especially using agricultural/fruit waste. This study presents efficient removal of an important and unsafe food grade dye, AR via adsorption. Waste watermelon peel waste has been used for the first time for treatmenting wastewater contaminated with AR. Waste was converted to two types of adsorbents, with and without subjecting it to pyrolysis. Both the adsorbents were characterized for functionality and crystallinity and used for conducting adsorption studies. Removal of dye was evaluated by intrinsic strategy of monitoring the model solutions under pre‐ and post‐adsorption conditions. Removal percentage of dye was determined by calculating its initial (Co) and final (Cf) concentrations in solution using the formula (see Eq. (1)). Various reaction parameters important for adsorption, viz. pH, adsorbent dose, residence time, reaction temperature and particle size were optimized. Results indicate that ~80 % and >92 % dye could be removed using 0.5 g/L adsorbent before and after pyrolysis respectively in 3.5 h from its 2 ppm concentration in modelled water.

Viable route to the manufacture of short carbon fiber-rich UHTC complex shapes with enhanced toughness

ZrB2 - based pasted, containing 5, 20, 45, 60 vol% short carbon fibers (Cf), were prepared in order to obtain complex shapes via direct ink writing, which were then sintered by hot pressing. The rheological behavior of the pastes indicated that at low Cf concentrations, the fibers act as a lubricant decreasing the paste viscosity. Above 20 vol% Cf, they act also as a binder creating an interconnected network that dominates over the lubrication effect, resulting in a viscosity increase. Complex shapes in the form of a hollow cylinder and a winglet with a functionally graded composition were then extruded and hot pressed, using a versatile powder bed method that enabled full densification with no need to use ad-hoc machined graphite inserts. Bars obtained from the direct ink writing process resulted in high alignment of the short fiber and displayed fracture toughness increase of 54% over that of the unreinforced matrix, while demonstrating a 42% increase with respect to conventionally hot pressed dry mixtures of ZrB2 and short fibers.This work shows the great potential of manufacturing complex shapes in ultra-high temperature ceramics matrices reinforced with short fibers for a plethora of design possibilities, including functional grading with control over layer composition, thickness and even alignment of short fiber.

Long term effect of corrosion inhibitor and associated cation type of chloride ions on chloride profile of concrete exposed to composite chloride-sulfate environment

This paper experimentally investigated the effect of nitrite-based corrosion inhibitor and cation type namely Na+, Mg2+ and Ca2+ associated with chloride ions on free chloride (CF) and total chloride (CT) ion concentrations of concrete exposed to composite chloride-sulfate (Cl-+SO42-) environment. Concrete cubes were prepared using Portland pozzolana cement and w/c ratio of 0.55. Sodium nitrite (NaNO2) was used as a corrosion inhibitor at an admixed dosage of 3% by weight of cement. After curing, the cubes were subjected to composite Cl-+SO42- solutions such as NaCl + MgSO4, MgCl2 + MgSO4, and CaCl2 + MgSO4. Powder samples were collected at different depth intervals from the cubes to determine the CF and CT concentrations. Fourier transform infrared (FTIR) spectroscopy and Field emission scanning electron microscope (FESEM) analyses were carried to examine the microstructure of concrete. The experimental results indicated that addition of NaNO2 in concrete reduced the penetration of chloride ions. Concrete exposed to CaCl2 + MgSO4 solution mostly showed higher CF and CT concentrations than NaCl + MgSO4 solution followed by MgCl2 + MgSO4 solution. Results of microstructure study indicated the formation of different compounds in concrete exposed to composite Cl-+SO42- solutions.

청각(Codium fragile)을 첨가하여 제조한 막걸리의 발효 중 품질특성 및 항산화 효과

This study investigated the physicochemical, microbiological, antioxidant, and sensory characteristics of Makgeolli supplemented with 10, 20, and 30% Codium fragile (Cf) during an 8-day fermentation period. The pH and acidity on day 0 were lower in Makgeolli supplemented with Cf (pH 3.55-3.65, acidity 0.26-0.29%) than in the unsupplemented Makgeolli (control) (pH 3.72, acidity 0.23%). The pH and acidity of Cf Makgeolli on day 8 were 3.08-3.12 and 0.67-0.75%, respectively. The sugar content increased steadily until day 4 (8.1-8.5 Brix) and then decreased steadily (6.5-6.8 Brix). The alcohol content increased steadily until day 8 (13.2-14.3%). The pH decreased, acidity increased, and alcohol content increased significantly (all P<0.05), with stepwise increases in fermentation time and Cf concen trations. The lactic acid bacteria counts were 9.28-9.37 log versus 8.18 log in the control. The DPPH (1,1-diphenyl- 2-picrylhydrazyl) and ABTS [2,2''-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging activities were higher in Cf Makgeolli (DPPH 74.63-84.64%, ABTS 51.01-64.79%) than in the control (DPPH 30.97%, ABTS 21.21%). Makgeolli supplemented with 10 and 20% Cf had the highest taste, smell, and overall acceptance scores. This study suggests that Makgeolli supplemented with 10 and 20% Cf could be developed due to its good physico chemical and microbiological characteristics, including high antioxidant properties and good consumer acceptance.

Tribo-mechanical characterization of spark plasma sintered chopped carbon fibre reinforced silicon carbide composites

Short carbon fibre (Cf) reinforced silicon carbide (SiC) composites with 7.5wt% alumina (Al2O3) as sintering additive were fabricated using spark plasma sintering (SPS). Three different Cf concentrations i.e. 10, 20 and 30wt% were used to fabricate the composites. With increasing Cf content from 0 to 20wt%, micro-hardness of the composites decreased ~28% and fracture toughness (KIC) increased significantly. The short Cf in the matrix facilitated enhanced fracture energy dissipation by the processes of crack deflection and bridging at Cf/SiC interface, fibre debonding and pullout. Thus, 20wt% Cf/SiC composite showed >40% higher KIC over monolithic SiC (KIC≈4.51MPam0.5). Tribological tests in dry condition against Al2O3 ball showed slight improvement in wear resistance but significantly reduced friction coefficient (COF, μ) with increasing Cf content in the composites. The composite containing 30wt% Cf showed the lowest COF.

Optical diagnostics of radio-frequency plasmas containing CHF3 and CHF3/O2: Laser-induced fluorescence of CF2, CF, and O atoms, and optical emission from H, F, and O

Laser-induced fluorescence (LIF) has been used to measure absolute concentrations of CF2, CF, and O atoms in a parallel-plate capacitatively coupled radio-frequency-driven plasma containing CHF3 and its mixtures with Ar and O2 at pressures between 50 and 500 mTorr. In CHF3 the spatial distribution of CF2 peaks at the driven electrode, and shows the importance of surface processes for its production. Time-resolved studies show evidence for its homogeneous chemical removal. CF concentrations are an order of magnitude lower than those of CF2, and removal by reaction with H atoms is consistent with time-resolved data taken on plasma extinction. For both radicals the absolute concentrations are higher than those found for similar plasmas in CF4. In the presence of O2 the fluorinated radical concentrations drop to below the detection limit, and the influence of surface removal processes is again invoked to explain the increase in O atom concentration observed when a small amount of CHF3 is added to a dominantly O2 gas flow. Optical emission from excited F, H, and O atoms is observed, and even when corrected by actinometry, is shown to be an unreliable indicator of the relative concentration of the ground-state species because of contributions from dissociative excitation of stable species in the discharge. Excited H atoms are found to be translationally hot from measurements of their linewidths, and are clearly not all formed from excitation of H atoms. Time-resolved actinometry (TRA) can be used in some cases to remove the contribution to the emission from dissociative excitation, but in the case of O atoms where both LIF and TRA were compared, the influence of a time-dependent dissociative excitation step complicates the analysis and is attributed to the presence of other species such as O2(a1Δg) in the discharge.

Pulsed plasma-enhanced chemical vapor deposition from CH2F2, C2H2F4, and CHClF2

Pulsed plasma enhanced chemical vapor deposition films have been grown from 1,1,2,2-C2H2F4, CH2F2, and CHClF2. C 1s x-ray photoelectron spectroscopy indicates a prevalence of C¯–CF species in the films from C2H2F4 and CH2F2, whereas CF2 species dominate the films from CHClF2. The CFx species distributions for the films are largely controlled by the competition between CF2-producing and HF elimination reactions in the pulsed plasmas. Dominance by HF elimination produces films with high C¯–CF and CF concentrations (e.g., CH2F2), whereas dominance by CF2-producing reactions leads to films with higher CF2 concentrations (e.g., CHClF2). The % CF3 in the film is lowest for the precursor having the lowest F:H ratio, CH2F2. Little or no hydrogen was detected in the deposited films. Pulsed plasma films from all three precursors gave dielectric constants of 2.4, with loss tangents on the order of 10−2. Dielectric measurements of pulsed plasma films from hexafluoropropylene oxide gave a dielectric constant of 2.0±0.1 with a loss tangent of 0.009.

Pulsed Plasma Enhanced Chemical Vapor Deposition from CH2F2, C2H2F4, and CHCIF2

ABSTRACTPulsed plasma enhanced chemical vapor deposition films have been grown from C2H2F4, CH2F2, and CHCLF2. C-Is x-ray photoelectron spectroscopy (XPS) indicates a prevalence ofC-CF species in the films from C2H2F4and CH2F2, whereas CF2species dominate the films from CHC1F2. The CFxspecies distributions for the films are largely controlled by the competition between CF2-producing and HF elimination reactions in the pulsed plasmas. Dominance by HF elimination produces films with highC-CF and CF concentrations (e.g., CH2F2), whereas dominance by CF2-producing reactions leads to films with higher CF2concentrations (e.g., CHCIF2). The % CF3in the film is lowest for the precursor having the lowest F:H ratio, CH2F2. Little or no hydrogen was detected in the deposited films. Thermal degradation of films from C2H2F4and CH2F2, as probed by solid-state nuclear magnetic resonance (NMR) spectroscopy, shows a loss through CF3detachment and HF elimination. Pulsed plasma films from all three precursors gave dielectric constants of 2.4, with loss tangents on the order of 10−2. Dielectric measurements of pulsed plasma films from hexafluoropropylene oxide (HFPO) gave a dielectric constant of 2.0 ± 0.1 with a loss tangent of 0.009.

Tracing Hydrologic Pathways Using Chloride at the Panola Mountain Research Watershed, Georgia, USA

An analysis of chloride (Cl−) concentrations and fluxes at the 41 ha Panola Mountain Research Watershed indicates that Cl− may be used effectively to differentiate “new” and “old” water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the “new” water inputs, are marked by low Cl− concentrations ( 30 µeg L−1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from this hillslope site (20 m from the stream) contributes to streamwater during individual rainstorms. The source of streamflow, therefore, must be a combination of channel interception, overland flow and soil water from near-channel areas, and runoff from a 3 ha bedrock outcrop in the headwaters. Groundwater contribution to streamflow was estimated using CF concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the streamflow and from 1985 to 1995, contributed 75% of the streamflow. Rainfall was the source of 45% of the Ct flux from the watershed in the long term; the remaining Cl− is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, “new” water can contribute 95% of the runoff.

Factors Affecting Vitamin E Production Using Plant Cell Culture of Carthamus Tinctorius.

Factors affecting α-tocopherol production using safflower (Carthamus tinctorius) cells were studied from the engineering aspects for plant cell culture. The specific production rate was evaluated as a function of rate-limiting factors. The conditioning factor released from cells, dissolved oxygen (DO) and medium components were considered as the limiting factors responsible for the specific production rate. Increasing the conditioning factor enhanced α-tocopherol production. Increasing DO concentration up to 9 mg-O2/l also caused a linear increase in specific production rate. The specific production rate in batch cultivation decreased, however, at a constant DO concentration with a sufficient amount of the conditioning factor. In repeated batch cultivation, the specific production rate was recovered by the addition of fresh medium. These results showed that an essential component in the medium was exhausted at an early stage of the batch cultivation and that the medium-feeding operation with sufficient CF and DO concentrations was required to maintain high productivity. By repeated batch cultivation, the content of α-tocopherol in the cell was increased to 9 mg/100 g-dry cell, which was considerably higher than that in natural safflower seeds.

CF and CF2 actinometry in a CF4/Ar plasma

Relative ground state CF and CF2 concentrations have been measured in a 13.56-MHz rf CF4/Ar discharge using both laser-induced fluorescence (LIF) and actinometric techniques to assess the validity of actinometry for CF and CF2 over a limited parameter space of pressure and power. Relative measurements of the CF ( A2Σ − X2Π) system and the CF2 ( A1B1 − X1A1) system were made by LIF. Actinometric values were calculated from relative measures of the plasma-induced emission (PIE) intensity of the CF* ( B2Δ− X2Π) at 202.4 nm, CF2* ( A1B1 − X1A1) at 251.9 nm, and Ar* [4s′(1/2)°−4p′(1/2)] at 750.4 nm. Both LIF and PIE signals were spatially averaged over the bulk of the plasma. Steady-state actinometric and LIF measurements were compared for CF4/5% Ar discharges at pressures in the range of 500 to 1000 mTorr and nominal powers in the range of 20 to 100 W. Dynamic actinometric and LIF measurements of CF were made by modulating the discharge power and monitoring the CF transient at one set of conditions, 500-mTorr pressure and 70-W nominal power. Our results indicate that actinometric measurements of CF and CF2 correlate well with relative CF and CF2 LIF measurements under the studied conditions.

The role of thymidylate synthase in the response to fluoropyrimidine-folinic acid combinations.

A panel of human colorectal tumor cell lines has been examined to determine the role of TS in the response to fluoropyrimidine antimetabolites. Among these cell lines, the response to FdUrd does not correlate with the levels of TS. In cell lines HCT 116 and RCA, which are poorly responsive to FdUrd, structural alterations in TS have been identified. In HCT 116, two TS polypeptides are present: a common form, occurring in all the cell lines and a variant form. The variant TS polypeptide has a reduced affinity for the TS ligands, FdUMP and CH2H4PteGlu, relative to the common TS polypeptide. Clonal populations of HCT 116 that overproduce each form have been isolated. Clones that overproduce the variant polypeptide are 4-fold less responsive to TS-directed cytotoxic agents than those that overproduce the common; thus, the presence of the variant TS is associated with a reduced response to TS-directed cytotoxic agents. The response of cell line RCA to FdUrd is dependent upon the extracellular CF concentration: response increases as CF is increased. RCA contains a TS enzyme with reduced affinity for CH2H4PteGlu, relative to cell line C, which is sensitive to FdUrd at all CF concentrations. Both cells form high chain-length polyglutamates of CH2H4PteGlu at CF concentrations in which the response to FdUrd differs by 4-fold. In RCA, the TS structural gene is variant, relative to the other cell lines. This variation may underlie the altered enzyme affinity for CH2H4PteGlu and the sensitivity to modulation of FdUrd response by CF.

7-Hydroxymethotrexate cytotoxicity and selectivity in a human Burkitt's lymphoma cell line versus human granulocytic progenitor cells: Rescue by folinic acid and nucleosides

The cytotoxicity of 7-hydroxymethotrexate (7-OH-MTX), the primary plasma metabolite of methotrexate (MTX) in humans, was assessed by inhibition of colony formation in agar, using human bone marrow granulocyte-macrophage stem cells (CFU) from healthy volunteers and RAJI cells, a human Burkitt's lymphoma cell line. After a 2 hr exposure of cells to 7-OH-MTX, the concentrations necessary to produce a 50% inhibition of colony formation were 180 μ M and 10 μ M for bone marrow cells and for RAJI cells respectively. A continuous incubation with 20 μ M folinic acid (CF) protected the RAJI cells from 7-OH-MTX cytotoxicity at concentrations below 5 μ M but was not able to completely reverse 7-OH-MTX effects at higher doses. Continuous incubation of 7-OH-MTX-preloaded cells (2 hr, id 90) with the end products of folate-dependent reactions, adenosine (100 μ M) and thymidine (10 μ M), completely rescued RAJI cells from the 7-OH-MTX cytotoxic effects. Moreover, while thymidine alone had no effect on the 7-OH-MTX response curve, both adenosine alone or CF-adenosine combination produced 75% and 90% protection respectively. CF and adenosine concentrations necessary to achieve 90% protection were 20 and 100 μ M respectively. This study demonstrates that ( i) 7-OH-MTX can exhibit a cytotoxic selectivity for this human Burkitt's lymphoma cell line as compared to human bone marrow stem cells and ( ii) the cytotoxicity of 7-OH-MTX cannot be reversed by CF alone. These data suggest that 7-OH-MTX and/or its polyglutamylated derivatives may play an important role on different enzyme(s) involved in the interconversion of tetrahydrofolate cofactors necessary for the de novo purine biosynthesis.

Regulation of aortic endothelial vesicular uptake of cationized ferritin by plasmalemmal binding

Endothelial uptake of cationized ferritin (CF, pI > 9.0) was investigated in the rabbit aorta. After in situ perfusion with CF at concentrations less than 0.35 mg/ml in Tyrode's solution, the endothelial plasmalemmal membrane was partially covered by a ferritin monolayer except at some vesicle necks and regions of cell overlap where particles aggregated. At a concentration of 0.5 mg/ml, CF entered all luminal vesicles and bound to the membrane as a uniform layer usually several particles deep. A steady state was reached after 5 s; particle binding and vesicle filling were not affected by perfusion flow rate up to 20 ml/min. The number of particles per loaded vesicle ( F N L ) increased with the density of particles at vesicle necks (PD v), suggesting that particle concentration in the vesicle was in equilibrium with that at the neck. At CF concentrations above 1 mg/ml, binding sites at vesicle necks and elsewhere on the membrane became saturated and luminal vesicles became maximally loaded. Under these conditions, F N L was greater than that expected for equilibrium with the PD v found. Our findings indicate that anionic sites at vesicle necks and cell overlaps are more strongly negatively charged than elsewhere, and suggest that CF vesicle loading is regulated by the degree of binding at the neck and by the relative strength of the attractive forces at the neck and the vesicle interior.

Treatment of Experimental Staphylococcus aureus Abscesses: Comparison of Cefazolin, Cephalothin, Cefoxitin, and Cefamandole

Cefazolin (CZ), cephalothin (CF), cefoxitin (CX), and cefamandole (CM) were evaluated in therapy of Staphylococcus aureus infection produced in perforated table tennis balls placed intraperitoneally in rabbits. Four weeks after placement of two balls in each rabbit, a beta-lactamase producing strain of S. aureus was injected into one of the balls. Twenty-four hours later therapy was initiated with 40 mg of CZ or 80 mg of CF, CX, or CM per kg intramuscularly every 6 h. After 24 h of treatment, the mean log(10) colony-forming units per ml were 7.1 for CZ, 6.7 for CF, 6.5 for CX, and 7.2 for CM. After 72 h the mean log(10) colony-forming units per ml were 5.0 for CZ, 4.1 for CF, 3.6 for CX, and 5.6 for CM. After 8 days, the titers were 1.6/ml for CZ, 1.0 for CF, 1.9 for CX, and 3.6 for CM. CZ serum levels were about double CF and CX levels and about two-thirds of CM levels. In sterile ball fluid CZ and CM levels were more than double CF or CX concentrations. Concentrations of all four antibiotics were lower in infected balls.

Shock-Tube Determination of the C2(A 3Π→X 3Π) and CF(A 2Σ+→X 2Π) Band-System Oscillator Strengths

Reflected-shock gas mixtures of C2ClF3, CF4, and C2F4 in excess argon were used to produce emission spectra of the C2(A 3Π—X 3Π) and CF(A 2Σ+—X 2Π) band systems. Absolute intensities of these electronic transitions were measured at several different wavelengths. Spectral data analyzed with equilibrium C2 and CF concentrations based on current JANAF heats of formation of the CF2 and CF radicals yielded for the Swan system the oscillator strength f(0, 0) in emission, 0.017±0.005 and for the CF system, 0.046±0.014. By reduction of the same data with recent shock-tube heats of formation, the oscillator strength f(0, 0) for the Swan system was 0.028±0.009 and that for the CF system, 0.0051±0.0015.