Fluorocarbon Solution Research Articles

Experimental investigation and molecular dynamics study on the influence of non-ionic fluorocarbon solutions on the fast-wetting mechanism of coal dust

To explore methods for enhancing the wetting performance of coal dust to mitigate its hazards, this study selected four different structures of non-ionic fluorocarbon solutions: perfluorinated propyl acrylate (PFPA), perfluorooctyl acrylate (PFTA), perfluorooctyl sulfonyl phenyloxy ethyl methylacrylate (PPM), and perfluoro propanoic acid (PFA). The dynamic wetting performance and mechanisms of these solutions on coal dust were measured and analyzed through kinetic calculations. The results indicate that all four fluorocarbon solutions achieve optimal wetting performance at a concentration of 0.3 %. Comprehensive analysis shows that their wetting ability follows the order PFPA > PFTA > PPM > PFA. Further analysis reveals that coal dust treated with PFPA shows an increase in structures such as COOH and CO. The relative concentration distribution indicates partial overlap between the fluorocarbon solution and water, with an overlap range of 8.2 Å. Additionally, the maximum diffusion coefficient is 0.577 Å/ps, and the system’s adsorption energy is the highest at −5757.25 kcal/mol.

Experimental and kinetic analysis of the fluorocarbon structures and coal particles at the microscale

Understanding the dynamic wetting process between liquid droplets and coal dust particles is crucial. Compared to other substances, coal possesses a more intricate microscale molecular chemical structure, with coal's molecular chemical and physical structural characteristics being the primary microscale factors influencing its wetting properties. To enhance the wetting and permeability performance of coal dust, an analysis of the microstructural influences on the wetting process of coal dust through experiments and simulations with five different structured fluorocarbon solutions: perfluorooctane sulfonate sodium (A1), perfluoroisopropyl acrylate (A2), perfluorooctane sulfonic acid ammonium salt (A3), perfluorooctyl alcohol polyoxyethylene ether (N1), and perfluorohexyl ethanol polyoxyethylene ether (N2), was conducted. A wetting theory model (collision–adsorption–immersion) was proposed based on experiments with different concentrations and types of surface tension, and wetting experiments were conducted based on this theory model. The results indicate that smaller coal particle sizes facilitate solution penetration, with the N2 solution demonstrating the best wetting and permeation effects. Microstructural experimental analysis revealed that N2 has more polar functional group structures than the other four fluorocarbon solutions. To further investigate the forces of different structures on coal particles, a molecular dynamics model was employed, and the simulation results indicated that the interaction forces and the number of hydrogen bonds representing the adsorption capacity in the N2 system were the highest.

Integrated design of a robust superhydrophobic cement mortar layer via sizing sand grains

This work reported a facile route for fabricating super-hydrophobic concrete via sizing sand grains. It was found that mixing the sands with a size ranging from 150–180 μm into cement enabled the formation of a lotus-like surface with a papillary structure at micro-scale. SEM showed that the size of bumper was about 3 μm. When spraying a fluorocarbon solution onto this surface, the porous nature of the cement matrix showed the advantage of taking the fluorocarbon into the internal structure of the concrete via capillary force. As a result, the sub surface up to a depth of ∼1.5 mm were transformed into a thick superhydrophobic layer directly. The contact angle (CA) of water droplets could reach 157° on this surface, and which could remain more than 150° after abrasion 100 cycles under a weight of 300 g at 360 grit sandpaper. This thick hydrophobic layer significantly reduced the corrosion rate of the steel the concrete at the Cl- environment by 620 times. The measurement of British pendulum number and compression strength revealed that this superhydrophobic layer was beneficial for maintaining the friction coefficient of the concrete surface in wet condition without altering the mechanical integrity of the concrete.

Interactions of superhydrophobic carbon soot coatings with short alkyl chain alcohols and fluorocarbon solutions

Carbon soot is a nanomaterial, whose extreme water repellency determines its potential industrial applicability in anti-fouling coatings, anti-icing systems, chemical sensors and drag reducing surfaces. The wettability and mechanical durability of the soot can be adjusted through an appropriate chemical treatment, but the underlying mechanism is yet unknown. In this paper, we provide new insights regarding the missing link between the fundamentals of soot-alcohol-fluorocarbon interactions and the derivative physicochemical features/properties of the coating. This is achieved by immersion of three types of superhydrophobic soot coatings in aqueous solutions of methanol, ethanol and isopropanol with variable concentration, and subsequent functionalization with fluorocarbon emulsion. The detailed structural and chemical analysis using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, reveals that the thickness, porosity and ratio of chemical bonds in the soot alter proportionally to the quantity of oxygen functional groups and point defects in the coating, as well as the alkyl chain length of alcohols. Moreover, the chemical treatment with fluorocarbon causes the formation of a thin fluoropolymer film on top of the soot that reinstates its superhydrophobicity and imparts oleophobicity of the surface. These findings are fundamental for further synthesis of soot coatings with controllable surface properties.

Rational strategy for the atmospheric icing prevention based on chemically functionalized carbon soot coatings

Although the superhydrophobic surfaces are preferable for passive anti-icing systems, as they provide water shedding before initiation of ice nucleation, their practical usage is still under debate. This is so, as the superhydrophobic materials are not necessarily icephobic and most of the synthesis techniques are characterized with low fabrication scalability. Here, we describe a rational strategy for the atmospheric icing prevention, based on chemically functionalized carbon soot, suitable for large-scale fabrication of superhydrophobic coatings that exhibit and retain icephobicity in harsh operational conditions. This is achieved through a secondary treatment with ethanol and aqueous fluorocarbon solution, which improves the coating’s mechanical strength without altering its water repellency. Subsequent experimental analyses on the impact dynamics of icy water droplets on soot coated aluminum and steel sheets show that these surfaces remain icephobic in condensate environments and substrate temperatures down to −35°C. Furthermore, the soot’s icephobicity and non-wettability are retained in multiple icing/de-icing cycles and upon compressed air scavenging, spinning and water jetting with impact velocity of ∼25m/s. Finally, on frosted soot surfaces, the droplets freeze in a spherical shape and are entirely detached by adding small amount of thermal energy, indicating lower ice adhesion compared to the uncoated metal substrates.

태양전지 2 단계 전극형성 공정을 위한 마스크 패턴공정 및 효율에 대한 영향성 연구

마스크를 이용하여 니켈 시드층의 형성 후 실버 도금을 통해 태양전지 상부전극을 형성하는 2 단계 전극형성 공정이 태양전지의 고효율화 방안으로 제안되었다. 본 연구에서는, 자외선 경화형 혹은 상변화 잉크를 고비용의 인쇄공정을 통해 마스크를 형성하는 방법을 대신하여, 코팅과 레이저의 복합공정을 통해 마스크를 형성하는 방법에 대해 제안하도록 한다. 마스크를 형성하는 물질로서 저비용의 저융점 왁스 혹은 플루오르카본 용액을 태양전지 웨이퍼 상에 코팅 후 레이저로 선택적으로 제거하여 전극패턴을 형성하였으며, 플루오르카본 용액 코팅이 왁스 코팅보다 패턴 균일도 측면에서 우수할 뿐만 아니라 통계적으로 0.16% 태양전지 효율증대를 유발한다는 점이 발견되었다.

Front Side Metallization Issues of a Solar Cell with Ink-jet Printing

The metallization of a multi-crystalline silicon solar cell has been challenged because the thickness reduction of a solar cell wafer decreases the breaking force of a solar cell wafer. Therefore, ink-jet printing has drawn attention of researchers in the art in place of conventional screen printing which requires the direct contact with a solar cell wafer to transfer silver paste. In this study, a preliminary study for the front side metallization of a solar cell wafer with ink-jet printing was conducted. Firstly, multicrystalline silicon solar cell wafers, the size of which is 156 mm by 156 mm, were coated with a 0.2 wt% fluorocarbon solution. After laser-patterning to selectively remove the SiNx layer and prepare for the surface energy patterned finger electrode regions, silver nanoparticulate ink was delivered with a piezo Drop-On-Demand ink-jet print head and baked at the peak temperature of 830 °C after drying at 100 °C. The measured cell efficiency of an ink-jet metallized solar cell was about 12.1% and the cause of the low cell efficiency is addressed here.

Measuring Oxygenation In Vivo with MRS/MRI—From Gas Exchange to the Cell

Oxygen plays a major role as a substrate in metabolic processes in numerous signaling pathways, in redox metabolism, and in free radical metabolism. To study the role of oxygen in normal and pathophysiological states, methods that can be used noninvasively are required. This review examines the potential of nuclear magnetic resonance techniques to study tissue oxygenation. It is written from a systems perspective, looking at detection methods with respect to the path that oxygen takes in the mammalian system-from the lungs, through the vascular system, into the interstitial space, and finally into the cell. Methods discussed range from those that are quantifiable, such as the assessment of spin lattice relaxation time in fluorocarbon solutions, to those that are more correlative, such as assessment of lactate and high energy phosphates. Since the methods vary in their site of application, sensitivity, and specificity to the quantification of oxygen, this review provides examples of how each method has been applied. This may facilitate the reader's understanding of how to optimally apply different methods to study specific biomedical problems.

Precatalyst separation paradigms: alkane functionalization in water utilizing in situ formed [Fe2O(η1-H2O)(η1-OAc)(TPA)2]3+, embedded in surface-derivatized silica, as an MMO model, and fluorous biphasic catalysis for alkane, alkene, and alcohol oxidation chemistry

Two precatalyst separation paradigms will be reviewed. The first involves the biomimetic, methane monoxygenase enzyme (MMO) precatalyst, [Fe2O(η1-H2O)(η1-OAc)(TPA)2]3+ (TPA=tris[(2-pyridyl)methyl]amine), 1 , formed in situ at pH 4.2 from [Fe2O(μ-OAc)(TPA)2]3+, 2 , which was embedded in an amorphous silicate surface modified by a combination of hydrophilic polyethylene oxide and hydrophobic polypropylene oxide, for ease of separation from the products formed. The resulting catalytic assembly was found to be a biomimetic model for the MMO active site within a hydrophobic macroenvironment, allowing alkane functionalization with t- butyl hydroperoxide (TBHP)/O2 in an aqueous reaction medium (pH 4.2). For example, cyclohexane was oxidized to a mixture of cyclohexanone, cyclohexanol, and cyclohexyl-t -butyl peroxide, in a ratio of ~3:1:2. The balance between polyethylene oxide and polypropylene oxide, tethered on the silica surface, was crucial for maximizing the catalytic activity. Moreover, the mechanism for the silica-based catalytic assembly was found to occur via the Haber–Weiss process. The second precatalyst separation paradigm, the use of the fluorous solvents, which is predicated on solubilizing the precatalyst in a fluorocarbon solution, allows the functionalization of alkanes and alkenes, while selective oxidation of alcohols to aldehydes was also possible; both precatalyst and product are in separate solvent phases. A discussion concerning both separation of precatalyst from product approaches will be presented.

Toward Ideal (Trans)esterification by Use of Fluorous Distannoxane Catalysts

AbstractFor Abstract see ChemInform Abstract in Full Text.

Toward ideal (trans)esterification by use of fluorous distannoxane catalysts.

1,3-Disubstituted tetrakis(fluoroalkyl)distannoxanes, (XR(2)SnOSnR(2)Y)(2) (R = C(6)F(13)C(2)H(4) and C(4)F(9)C(2)H(4)), are highly fluorophilic and exhibit large partition coefficients in favor of fluorocarbon solvents over common organic solvents due to a double-layered structure where the stannoxane core is covered by fluoroalkyl groups. Under catalysis of these Lewis acids, fluorous technology allows novel transesterification and esterification in which a 100% yield of the desired esters is achievable with reactants in a strict 1:1 ratio. The catalysts are recovered from the fluorous phase quantitatively. More practically, the catalyst in fluorocarbon solution can be recycled for use in the next reaction repeatedly.

Quantitative analysis of intestinal motor patterns: Spatiotemporal organization of nonneural pacemaker sites in the rat ileum

Background & Aims: Intestinal contractions are triggered by electric activity of pacemaker cells within the smooth muscle. However, the precise spatial organization of the pacemaker system is unknown. We directly assessed the spatiotemporal organization of pacemakers by video image analysis combined with manometry and electromyography. Methods: Isolated segments of rat ileum were perfused arterially with oxygenated fluorocarbon solution and luminally with saline. Luminal end pressures, extracellular electric activity, and images of the intestine were recorded simultaneously. Tetrodotoxin, NG-nitro-L-arginine methyl ester (L-NAME), L-arginine, and eserine were administered arterially. Results: Myogenic contractions originated in discrete areas (dominant pacemakers) and propagated faster in aboral than in oral direction. Dominant pacemakers were distributed along the intestine at regular intervals. The preparations were mostly driven by 1 pacemaker at the time, but 2 or 3 pacemakers with different frequencies could be active simultaneously. Tetrodotoxin decreased aboral propagation velocity and revealed multiple regularly spaced pacemaker areas. Eserine increased, whereas L-arginine decreased, their frequency. After L-NAME, pacemaker activity increased and isolated pacemakers with higher frequency appeared. Conclusions: Nonneural pacemakers in rat ileum are functionally organized not as a continuous system but show a segmental arrangement, spatially and temporally modulated by neural activity.GASTROENTEROLOGY 2000;119:386-394

Small intestinal dysmotility following abdominal irradiation in the rat small intestine.

Abdominal symptoms such as diarrhoea, abdominal cramps and vomiting are common during and after abdominal radiotherapy for gynaecological and pelvic malignancy. It has recently been recognized that small intestinal dysmotility may contribute to these symptoms but the underlying mechanisms are unclear in part because of the technical difficulties inherent in performing studies in irradiated small intestine. The aim of the current study was to evaluate small intestinal motor activity using perfused micromanometric techniques in 6-8-cm segments of ileum during arterial perfusion with isotonic oxygenated fluorocarbon solution. Intestinal segments from six rats were studied 4 days after treatment with 10 Gy abdominal irradiation. Ileal segments from nine nonirradiated animals acted as controls. For each experiment the total number of pressure waves, high-amplitude (> 20 mmHg, long-duration > 6 sec) pressure waves, and long (> 20 associated) bursts of pressure waves were determined. Irradiation had no effect on the overall number of pressure waves, but increased high-amplitude long-duration (HALD) pressure waves (248 vs 7, P < 0.01). In control animals HALD waves were localized to a single recording site but after radiotherapy 74% of HALD waves were temporally associated with similar pressure waves in other manometric channels. Forty-seven per cent of associated HALD waves migrated aborally. Retrograde migration of HALD waves was seen in five segments following irradiation. Irradiation abolished bursts of > 20 pressure waves.

Fluorine-19 Nuclear Magnetic Resonance Relaxation Analysis of the Interaction of Fluorocarbon with Oxygen

Fluorine-19 nuclear spin relaxation rates for fluorocarbon solutions involving oxygen have been measured over a wide frequency range (10 to 235MHz) at 25°C. The19F relaxation of the solvents involving paramagnetic oxygen can be explained by Bipolar electron spin-nuclear spin interaction modulated by both translational diffusion (τd of 2.0×10-11 and 2.5×10-11s for C6F6and C6H4(CF3)2, respectively) and the lifetime of the short-lived complex (τh of 7.6×10-13 and 1.3×10-12s for C6F6 and C6H4 (CF3)2, respectively), although the translational contribution is dominant. The translational motions account for 81 and 70% of the relaxation process and are characterized in the present analysis by closest distances of 3.6 and 3.8A for C6F6 and C6H4(CF3)2, respectively.

Hypertension with hemodilution prevents multifocal cerebral hypoperfusion after cardiac arrest in dogs.

Improved neurological outcome with postarrest hypertensive hemodilution in an earlier study could be the result of more homogeneous cerebral perfusion and improved O2 delivery. We explored global, regional, and local cerebral blood flow by stable xenon-enhanced computed tomography and global cerebral metabolism in our dog cardiac arrest model. Ventricular fibrillation cardiac arrest of 12.5 minutes was reversed by brief cardiopulmonary bypass, followed by life support to 4 hours postarrest. We compared control group I (n = 5; mean arterial blood pressure, 100 mm Hg; hematocrit, greater than or equal to 35%) with immediately postarrest reflow-promoted group II (n = 5; mean arterial blood pressure, 140-110 mm Hg; hypervolemic hemodilution with plasma substitute to hematocrit, 20-25%). After initial hyperemia in both groups, during the "delayed hypoperfusion phase" at 1-4 hours postarrest, global cerebral blood flow was 51-60% of baseline in group I versus 85-100% of baseline in group II (p less than 0.01). Percentages of brain tissue voxels with no flow, trickle flow, or low flow were lower (p less than 0.01) and mean regional cerebral blood flow values were higher in group II (p less than 0.01). Global cerebral oxygen uptake recovered to near baseline values at 3-4 hours postarrest in both groups. Postarrest arterial O2 content, however, in hemodiluted group II was 40-50% of that in group I. Thus, the O2 uptake/delivery ratio was increased (worsened) in both groups at 2-4 hours postarrest. After prolonged cardiac arrest, immediately induced moderate hypertensive hemodilution to hematocrit 20-25% can normalize cerebral blood flow patterns (improve homogeneity of cerebral perfusion), but does not improve cerebral O2 delivery, since the flow benefit is offset by decreased arterial O2 content. Individualized titration of hematocrit or hemodilution with acellular O2 carrying blood substitute (stroma-free hemoglobin or fluorocarbon solution) would be required to improve O2 uptake/delivery ratio.

Hemodynamic effects and oxygen transport properties of a new blood substitute in a model of massive blood replacement

Recent concerns regarding the safety of the national blood supply have rekindled interest in the development of blood substitutes. Clinical studies have dampened the initial enthusiasm for fluorocarbon solutions as blood substitutes. The potential of hemoglobin solutions as blood substitutes has continued to stimulate investigations. However, the development of an ideal hemoglobin-derived blood substitute has eluded investigators for the past century. A persistent problem has been the inability to develop hemoglobin solutions that provide adequate oxygen and carbon dioxide exchange, while avoiding toxicity that precludes clinical safety and long-term survival. Traditionally, investigators have focused on human hemoglobin solutions. The use of outdated banked blood or pedigree human donor blood as a hemoglobin source poses continued disease transmission risks and a prohibitively limited supply. We evaluated the hemodynamic and gas transport effects of a new purified, polymerized bovine hemoglobin preparation. Bovine hemoglobin oxygen affinity is regulated by chloride ion. The concentration of chloride ions in human plasma results in excellent oxygen transport properties in a stroma-free environment. In addition, unlike human blood, bovine blood is a more disease-free hemoglobin source that is available in large supply. We exchange-transfused eight conscious sheep with this new polymerized bovine hemoglobin solution. All animals tolerated greater than or equal to 95% exchange transfusion to reach a final ovine hematocrit of 2.4 +/- 0.5% with stable hemodynamics and no clinical evidence of distress. The exchange transfusion with bovine hemoglobin polymer resulted in a final plasma hemoglobin concentration of 6.1 +/- 1.6 gm/dl, which supported oxygen consumption at baseline levels. All animals that were exchange transfused with this preparation survived long term with rapid resynthesis of ovine erythrocytes.

Ischemic myocardial protection: Comparison of nonoxygenated crystalloid, oxygenated crystalloid, and oxygenated fluorocarbon cardioplegic solutions

This study was designed to compare myocardial protection with a nonoxygenated crystalloid solution, an oxygenated crystalloid solution, and an oxygenated fluorocarbon cardioplegic solution. Postischemic ventricular performance was studied in three equal (N = 7) groups of dogs subjected to 120 minutes of global ischemia induced at an average myocardial temperature of 18.5 degrees +/- 1.4 degrees C (range 17.0 degrees to 21.0 degrees C). Left ventricular global and regional function was evaluated by sonomicrometry and micromanometers before ischemia and at 45 and 60 minutes after ischemia. Stroke volume index, left ventricular pressure-minor external diameter loop area, percent shortening, first derivative of left ventricular pressure, mean velocity of circumferential fiber shortening, and the slope of the end-systolic pressure were used to evaluate myocardial contractility. In vitro oxygen content of the three cardioplegic solutions was measured at a mean injection temperature of 8.3 degrees +/- 0.6 degrees C: 0.8 +/- 0.1 vol% (nonoxygenated crystalloid cardioplegia), 3.2 +/- 0.2 vol% (oxygenated crystalloid cardioplegia), and 6.2 +/- 0.2 vol% (oxygenated fluorocarbon cardioplegia). Recovery of global and regional function was significantly (p less than 0.05) better with both oxygenated solutions than with the nonoxygenated solution. Differences between the oxygenated crystalloid and fluorocarbon groups were not significant. We conclude: (1) Compared to nonoxygenated crystalloid cardioplegia, oxygenated crystalloid and oxygenated fluorocarbon cardioplegic solutions gave superior myocardial protection during 2 hours of ischemic arrest; (2) no difference was found in protective effects between an oxygenated crystalloid and an oxygenated fluorocarbon solution.

The simultaneous measurements of tissue oxygen concentration and energy state by near-infrared and nuclear magnetic resonance spectroscopy.

The oxygenation and energy states of brain tissues were measured simultaneously by near-infrared photometry and nuclear magnetic resonance spectroscopy in situ. In both cat and dog, the critical hemoglobin oxygenation was 10%, below which the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) started to fall. The fall of PCr/Pi paralleled the reduction of copper in cytochrome aa3. The separation of the cytochrome aa3 signal from that of hemoglobin by our optical method was confirmed by the substitution of blood by fluorocarbon solution. The energy-oxygen diagram (PCr/Pi against hemoglobin oxygenation, HbO2) was the same in normal- and fluorocarbon substituted cats, but energy curve shifted to the right in the latter when PCr/Pi plotted against the inspired oxygen, FiO2.

The ability of oxygenated fluorocarbon solution to minimize ischemic skeletal muscle injury.

The amputated canine limb was used to create a devascularized skeletal-muscle-containing model. The extremity was perfused with one of several solutions or merely cooled as a preservative measure during the devascularized period and then replanted. Perfusion of the limb with oxygenated fluorocarbon solution minimized edema formation and leakage of skeletal muscle enzymes into the serum following revascularization as compared to the other perfusates or to mere cooling. Histopathologic changes within the revascularized muscle were also minimized by the oxygenated fluorocarbon perfusion. It is probable that these findings will correlate with improved function of replanted extremities or free muscle flaps. The applicability of these findings to human extremity replantation and free-flap transfer is postulated. However, long-term human studies will be necessary to assess the function of extremities and flaps perfused with this solution prior to its general use in extremity replantation and free-flap transfer.

Effects of Synthetic Blood Combined with Contrast Medium on Coronary Endothelium: An Experimental Study

The study described was carried out to evaluate endothelial injury following incubation of coronary material in contrast medium and in contrast medium diluted with fluorocarbon solution. Six porcine hearts were excised and isolated. Immediately thereafter, pieces of the main coronary arteries and ascending aortas were incubated in four different solutions: 1) blood, 2) contrast medium, 3) fluorocarbon solution, 4) fluorocarbon--contrast medium (1:1). Flow surfaces and coronary endothelial morphology were evaluated by scanning electron microscopy (SEM). Porcine blood (at room temperature) preserved endothelial structures intact but, in two samples, small patchy areas of denuded surface were found. Four minutes' immersion in contrast medium resulted in easily visible changes in the endothelial lining and individual cells. Denuded flow surface areas were common, the intact surface morphology was flattened. After 7 minutes, destruction was total. The addition of fluorocarbon solution to contrast medium (1:1) diminished the changes, which also occurred later than after incubation in pure contrast medium. After 7 minutes, separate endothelial cells were still identifiable but the microvilli had disappeared. Fluorocarbon solution preserved the endothelial lining well during a 10-minute follow-up period. The experimental protocol described confirmed the deleterious effect of contrast medium on coronary endothelial lining, which could be reduced to some extent by adding fluorocarbon solution to contrast medium.