Search

Hypothesis Lung surfactant protects lung tissue and reduces the surface tension in the alveoli during respiration. Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5), which invades primely through inhalation, can deposit on and interact with the surfactant layer, leading to changes in the biophysical and morphological properties of the lung surfactant. Experiments Langmuir monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and clinical surfactant Calsurf were investigated with a PM2.5 model injected into the water subphase, which were characterized by surface pressure-area isotherms, Brewster angle microscopy, atomic force microscopy, fluorescent microscopy, and x-ray photoelectron spectroscopy. The binding between DPPC/Calsurf and PM2.5 was studied using isothermal titration calorimetry. Findings PM2.5 induced the expansion of the monolayers at low surface pressure (п) and film condensation at high п. Aggregation of PM2.5 mainly occurred at the interface of liquid expanded/liquid condensed (LE/LC) phases. PM2.5 led to slimmer and ramified LC domains on DPPC and the reduction of nano-sized condensed domains on Calsurf. Both DPPC and Calsurf showed fast binding with PM2.5 through complex binding modes attributed to the heterogeneity and amphiphilic property of PM2.5. This study improves the fundamental understanding of PM2.5-lung surfactant interaction and shows useful implications of the toxicity of PM2.5 through respiration process.

Developing effective internal wound dressing materials is important for postoperative tissue regeneration while remains a challenge due to the poor biological environment-adaptability of conventional materials. Here, we report an example of injectable self-healing hydrogel based on gastric environment-adaptive supramolecular assembly, and have explored its application for gastric perforation healing. By leveraging the gastric environment-modulated supramolecular interactions, the self-assembled hydrogel network is orchestrated with sensitive thermo-responsibility, injectability, printability and rapid self-healing capability. The hydrogel dressing can effectively inhibit the attachment of microorganisms and demonstrates outstanding antibiofouling property. In vivo rat model further demonstrates the as-prepared hydrogel dressing simplifies the surgical procedures, reduces postoperative complications as well as enhances the healing process of gastric perforation compared with the conventional treatment. This work provides useful insights into the development of biological environment-adaptive functional materials for various biomedical applications.

The SARS-CoV-2 virus that causes the COVID-19 epidemic can be transmitted via respiratory droplet-contaminated surfaces or fomites, which urgently requires a fundamental understanding of intermolecular interactions of the coronavirus with various surfaces. The corona-like component of the outer surface of the SARS-CoV-2 virion, named spike protein, is a key target for the adsorption and persistence of SARS-CoV-2 on various surfaces. However, a lack of knowledge in intermolecular interactions between spike protein and different substrate surfaces has resulted in ineffective preventive measures and inaccurate information. Herein, we quantified the surface interaction and adhesion energy of SARS-CoV-2 spike protein with a series of inanimate surfaces via atomic force microscopy under a simulated respiratory droplet environment. Among four target surfaces, polystyrene was found to exhibit the strongest adhesion, followed by stainless steel (SS), gold, and glass. The environmental factors (e.g., pH and temperature) played a role in mediating the spike protein binding. According to systematic quantification on a series of inanimate surfaces, the adhesion energy of spike protein was found to be (i) 0–1 mJ/m2 for hydrophilic inorganics (e.g., silica and glass) due to the lack of hydrogen bonding, (ii) 2–9 mJ/m2 for metals (e.g., alumina, SS, and copper) due to the variation of their binding capacity, and (iii) 6–11 mJ/m2 for hydrophobic polymers (e.g., medical masks, safety glass, and nitrile gloves) due to stronger hydrophobic interactions. The quantitative analysis of the nanomechanics of spike proteins will enable a protein–surface model database for SARS-CoV-2 to help generate effective preventive strategies to tackle the epidemic.

Underwater adhesion is a great challenge for the development of adhesives as the attractive interfacial intermolecular interactions are usually weakened by the surface hydration layer. The coacervation process of sessile organisms like marine mussels and sandcastle worms has inspired substantial research interest in the fabrication of long-lasting underwater adhesives, but they generally suffer from time-consuming curing triggered by surrounding environmental changes and cannot reserve the adhesiveness once damaged. Herein, an instant and repeatable underwater adhesive was developed based on the coacervation of tannic acid (TA) and poly(ethylene glycol)77-b-poly(propylene glycol)29-b-poly(ethylene glycol)77 (PEG-PPG-PEG, F68), which was driven by hydrogen-bonding interaction, and the hydrophobic cores of F68 micelles offered an additional cross-linking to enhance the mechanical properties. The TA-F68 coacervates could be facilely painted on different substrates, exhibiting robust and instant underwater adhesion (with adhesion strength up to 1.1 MPa on porcine skin) and excellent repeatability (at least 1000 cycles), superior to the previously reported coacervates. Due to the biological activities of TA, the underwater adhesive displayed innate anticancer and antibacterial properties against different types of cancer cells and bacteria, showing great potential for diverse biomedical applications, such as injectable drug carriers, tissue glues, and wound dressings.

Although recent years have witnessed intense efforts and innovations in the design of flexible conductive materials for the development of next-generation electronic devices, it remains a great challenge to integrate multifunctionalities such as stretchability, self-healing, adhesiveness, and sensing capability into one conductive system for practical applications. In this work, for the first time, we have prepared a new electrically conductive elastomer composite that combines all these functionalities by triggering in situ polymerization of pyrrole in a supramolecular polymer matrix cross-linked by multiple hydrogen-bonding 2-ureido-4[1 H]-pyrimidinone (UPy) groups. The polypyrrole (PPy) particles were uniformly dispersed and imparted to the composite desirable conductive properties, while the reversible nature of the dynamic multiple hydrogen bonds in the polymer matrix allowed excellent stretchability, fast self-healing ability, and adhesiveness under ambient condition. The elastomer composite with the incorporation of 7.5 wt % PPy displayed a mechanical strength of 0.72 MPa with an elongation over 300%, where the rapid self-healing of the mechanical and electrical properties was achieved within 5 min. The elastic material also exhibited strong adhesiveness to a broad range of inorganic and organic substrates, and it was further fabricated as a strain sensor for the detection of both large and subtle human motions (i.e., finger bending, pulse beating). The novel PPy-doped conductive elastomer has demonstrated great potential as functional sensors for wearable electronics, which provides a facile and promising approach to the development of various flexible electronic materials with multifunctionalities by combining conductive components with supramolecular polymers.

Hydrogen-bonding interaction is one of the most developed approaches for generating supramolecular polymers, and self-assemblies solely based on hydrogen bonds are generally unstable in water. Although considerable efforts have been made to improve the stability of the hydrogen-bonded arrays by other interactions such as hydrophobic interactions, it still remains a challenge to elucidate the effects of surrounding environment on hydrogen bonding at the single-molecular level, which is crucial for developing desired hydrogen-bonded structures. In this work, for the first time, single-molecule force spectroscopy was employed to characterize the binding strength and dynamics of hydrogen-bonded 2-ureido-4[1H]-pyrimidinone (UPy) dimers in water in combination with molecular dynamics (MD) simulations, and the hydrophobic effect was investigated by tethering alkylene spacers of different lengths to the hydrogen binding moieties. The rupture force and unbinding energy of self-complementary UPy–UPy dimers were fou...

3,4-Dihydroxyphenylalanine (Dopa) is a mussel-inspired, unique and versatile adhesive moiety, while zwitterions are well-known for their antifouling and repellent properties. It is still unclear whether zwitterionic surfaces could effectively prevent the adhesion of Dopa units, and a zwitterion–Dopa interaction mechanism may lead to development of a novel wet adhesion strategy. Here we report single-molecule force spectroscopy (SMFS) between Dopa and zwitterionic molecules of opposite dipole orientations, with a much stronger bond dissociation energy for zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC, ∼19.4 kBT) than for [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (DMAPS, ∼10.8 kBT). The strong MPC–Dopa interaction could be attributed to the synergy of cation–π interaction and hydrogen bonding, but the DMAPS–Dopa interaction could only be attributed to hydrogen bonding, as further demonstrated by density functional theory (DFT) computation. Based on the orientation-mediated zwitterion–Dopa binding mechanism, we design a polymer containing both MPC and Dopa moieties as a promising underwater adhesive with a measured cohesion of 7.2–14.1 mJ m−2, even stronger than reported cation–π-facilitated underwater adhesives. The elucidated molecular interaction principles shed light on designing novel zwitterion–Dopa-mediated materials with wide applications in various fields such as tissue engineering scaffolds, cell-based screening and underwater adhesives.

Particulate matter (PM), which is the primary contributor to air pollution, has become a pervasive global health threat. When PM enters into a respiratory tract, the first body tissues to be directly exposed are the cells of respiratory tissues and pulmonary surfactant. Pulmonary surfactant is a pivotal component to modulate surface tension of alveoli during respiration. A lot of studies have proved that PM would interact with pulmonary surfactant to affect the alveolar activity, and meanwhile, pulmonary surfactant would be adsorbed to the surface of PM to change the toxic effect of PM. This review focuses on recent studies of the interactions between micro/nanoparticles (synthesized and environmental particles) and pulmonary surfactant (natural surfactant and its models), as well as the health effects that caused by PM through a few significant aspects, such as surface properties of PM, including size, surface charge, hydrophobicity, shape, chemical nature, etc. Moreover, in vitro and in vivo studies showed that PM leads to oxidative stress, inflammatory response, fibrosis, and cancerization in living bodies. By providing a comprehensive picture of PM-surfactant interaction, this review will benefit both researchers for further studies and policy-makers for setting up more appropriate regulations to reduce the adverse effects of PM on public health., Graphic Abstract Unlabelled Image, Highlights • Long-term exposure to particulate matter (PM) reduces life expectancy. • Pulmonary surfactant is the initial tissues contacted with PM . • The interaction behaviors of PM and pulmonary surfactant are systematically reviewed. • Surface properties of PM determine PM-surfactant interactions.

Coacervation plays a critical role in numerous biological activities such as constructing biological tissues and achieving robust wet adhesion of marine sessile organisms, which conventionally occurs when oppositely charged polyelectrolytes are mixed in aqueous solutions driven by electrostatic attraction. Here, a novel type of adhesive coacervate is reported, driven by hydrogen-bonding interactions, readily formed by mixing silicotungstic acid and nonionic polyethylene glycol in water, providing a new approach for developing coacervates from nonionic systems. The as-prepared coacervate is easily paintable underwater, show strong wet adhesion to diverse substrates, and has been successfully applied as a hemostatic agent to treat organ injuries without displaying hemolytic activity, while with inherent antimicrobial properties thus avoiding inflammations and infections due to microorganism accumulation. This work demonstrates that coacervation can occur in salt-free environments via non-electrostatic interactions, providing a new platform for engineering multifunctional coacervate materials as tissue glues, wound dressings and membrane-free cell systems.

Injectable, self-healing, and pH-responsive hydrogels are great intelligent drug delivery systems for controlled and localized therapeutic release. Hydrogels that show pH-sensitive behaviors in the mildly acidic range are ideal to be used for the treatment of regions showing local acidosis like tumors, wounds and infections. In this work, we present a facile preparation of an injectable, self-healing, and supersensitive pH-responsive nanocomposite hydrogel based on Schiff base reactions between aldehyde-functionalized polymers and amine-modified silica nanoparticles. The hydrogel shows fast gelation within 10 s, injectability, and rapid self-healing capability. Moreover, the hydrogel demonstrates excellent stability under neutral physiological conditions, while a sharp gel-sol transition is observed, induced by a faintly acidic environment, which is desirable for controlled drug delivery. The pH-responsiveness of the hydrogel is ultrasensitive, where the mechanical properties, hydrolytic degradation, and drug release behaviors can alter significantly when subjected to a slight pH change of 0.2. Additionally, the hydrogel's mechanical and pH-responsive properties can be readily tuned by its composition. Its excellent biocompatibility is confirmed by cytotoxicity tests toward human dermal fibroblast cells (HDFa). The novel injectable, self-healing, and sensitive pH-responsive hydrogel serves as a promising candidate as a localized drug carrier with controlled delivery capability, triggered by acidosis, holding great promise for cancer therapy, wound healing, and infection treatment.

Aims Evidence shows that aberrant expression of long non-coding RNA (lncRNA) is closely associated with tumor development and progression. However, the role of lncRNA in environmental carcinogen induced gastric tumorigenesis remains largely unknown. This study aimed at investigating the function role of lncRNA in N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) induce malignantly transformed human gastric epithelial cells. Main methods In this study, high-throughput sequencing and qRT-PCR assay revealed marked downregulation of lncRNA LOC101927497 in the malignant transformed gastric epithelial cells induced by MNNG (GES-1-T cells), gain-of-function and loss-of-function assays showed that LOC101927497 can suppress the proliferation and migration of GES-1-T cells in vitro. RNA antisense purification experiment showed that LOC101927497 interacted with miR-574-5p in GES-1-T cells the most obvious. Further studies suggested that LOC101927497 may function as a tumor suppressor by interacting with miR-574-5p. Key findings LncRNA LOC101927497 functions as a suppressor by interacting with miR-574-5p, thus inhibiting the malignant phenotype of GES-1-T cells. Significance To the best of our knowledge, this is the first study to demonstrate the role of lncRNA in MNNG-induced gastric tumorigenesis, and it will provide new insights into the role of lncRNA in environmental carcinogen-induced gastric cancer.

Facilitated transport membranes have been extensively applied in a myriad of industrial fields, in view of their distinctive capabilities of selective separation of target species (e.g., ions/small molecules). Despite much progress, it remains challenging to tackle the trade-off relationship between the stability and separation efficiency of these membranes. Herein, we propose a Janus facilitated transport membrane with asymmetric surface wettability and dense/porous structure by decorating a hydrophilic and dense polymer inclusion membrane (PIM) skin layer on the surface of a hydrophobic and microporous polyvinylidene fluoride (PVDF) membrane to achieve a notable balance between separation efficiency and leakage-resistance. With the hydrophilic PIM skin layer facing aqueous solutions whilst the hydrophobic PVDF membrane towards organic solution during separation process, the Janus facilitated transport membrane remarkably prevents the leakage of the liquids from 66.7% (using the plain PVDF membrane) to negligible. Through a rapid transformation of the transport mechanism from a short-term hopping in the dense PIM skin layer to an unobstructed motion in the microporous PVDF membrane matrix, the separation efficiency of the Janus facilitated transport membrane has been considerably enhanced from 25% (using the PIM) to about 70%. Investigation of the influencing factors on the structures, properties and separation performance of the Janus facilitated transport membrane suggests that the concentration of the PIM casting solution is of particular importance to the formation of the PIM skin layer and the asymmetric dense/porous structure of the membrane. In addition, the Janus facilitated transport membrane exhibits extraordinary mechanical properties and selectivity. Our work demonstrates that the Janus facilitated transport membrane holds great promise and a wide scope in versatile applications in water treatment, water-oil separation, and recovery of metal ions/small molecules in complex systems (e.g., water-oil-metal ions and water-oil-small molecules).

A single-color laser-induced collisional charge transfer system of Xe+–N2 is introduced, and the charge transfer process between Xe+ and N2 is observed. The laser-induced charge transfer (LICT) in Xe+–N2 system is experimentally investigated through time-of-flight (TOF) mass spectrometry, and the intensity dependence of product ions at ∼440 nm under several different conditions are measured, showing the impacts of laser parameters, mixing ratio, and pressure on the charge transfer process. Our results indicate that the charge transfer process between Xe+ and N2 can be enhanced by the joint action of the collisional and radiative interactions.

Aims Enhanced aerobic glycolysis is an essential hallmark of malignant cancer. Blocking the glycolytic pathway has been suggested as a therapeutic strategy to impair the proliferation of tumor cells. Metformin, a widely used anti-diabetes drug, exhibits anti-tumor properties. However, the underlying molecular mechanism of its action linking glucose metabolism with the suppression of proliferation has not been fully clarified. Main methods Stable isotope tracing technology and gas chromatography–mass spectrometry method were utilized to analyze the effect of metformin on glycolytic flux in HCC cells. Western blot and immunohistochemistry were utilized to analyze the expression of phosphofructokinase-1 (PFK1) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) in HCC cells or xenograft tumor tissues. Lactate measurement and glucose uptake assay were used to analyze the level of lactate and glucose in the presence of frucose-2,6-diphosphate (F2,6BP) in HCC cells treated with metformin. Key findings We found that metformin significantly impaired hepatoma cell proliferation by inhibiting the glycolytic flux via PFK1 blockade. Interestingly, activation of PFK1 by F2,6BP reverses the inhibitory effect of metformin on hepatoma cell proliferation and glycolysis. Mechanistically, PFKFB3，a potent allosteric activator of PFK1, was markedly suppressed through inhibiting hypoxia-induced factor 1 (HIF-1α) accumulation mediated by metformin. Significance Taken together these data indicate that HIF-1α/PFKFB3/PFK1 regulatory axis is a vital determinant of glucose metabolic reprogramming in hepatocellular carcinoma, which gives new insights into the action of metformin in combatting liver cancer.

Mussel-inspired phenol/amine deposition in wet adhesion provides a cost-effective strategy to readily fabricate functional coatings for a wide range of applications. The adhesion of phenol/amine to different substrates and the cohesion between phenol/amine are believed to play critical roles during the deposition process. However, the understanding on the correlation between the deposition capability and interaction behavior involved in the coating formation still remains incomplete, which limits further developing phenol/amine-based functional materials and coatings. In this work, we correlated the interaction forces between two phenol/amine coatings and between phenol/amine coating and different substrate surfaces with the deposition capability of phenol/amine using surface forces apparatus and atomic force microscopy. The mass ratio of phenol and amine was found to significantly influence the deposition behavior through regulating the surface properties of phenol/amine aggregates' cohesion strength between phenol/amine coatings. Furthermore, the strong adhesion measured between phenol/amine coating and substrates with varying surface chemistry was demonstrated to be able to effectively initiate the surface-independent phenol/amine deposition as well as the continuous growth of phenol/amine coatings. This work provides useful insights into the fundamental understanding of the interactions and deposition mechanism during phenol/amine deposition process, with implications for developing advanced phenol/amine-based coating materials for a wider range of applications.

Hypothesis Hydrophobic interaction is crucial in various colloidal phenomena and engineering processes involving air/water/solid systems where polar and nonpolar substances usually mingle with each other. The molecular-level heterogeneity of surface hydrophobicity could potentially disorder the interfacial water molecules and thus influence the hydrophobic interaction strength, but the underlying mechanism is not completely clear. Experiments The hydrophobic interactions between air bubbles and self-assembled monolayer surfaces bearing methyl and different polar moieties were precisely quantified via bubble probe atomic force microscope coupled with theoretical modeling analysis. Findings Increasing coverage of surface polar moieties on binary-component surfaces can apparently lower surface hydrophobicity θc, but hardly affect hydrophobic interaction’s decay length D0. Changing pH has no detectable effect on hydrophobic interactions involving CH3 and CH3/OH-ended surfaces. In contrast, θc and D0 decrease monotonically with pH rising for CH3/COOH-ended surface, because high pH tends to dissociate –COOH, enhancing the surface hydrophilicity and weakening the hydrophobic interaction. For CH3/NH2-ended surface, θc and D0 decrease sequentially with pH declining, because protonation of –NH2 can lower the surface hydrophobicity and weaken the hydrophobic interaction. This work improves the fundamental understanding of hydrophobic interactions in air/water/solid systems and provides useful insights into the interfacial assembly processes in relevant engineering applications.

Zwitterionic groups have been widely used in antibiofouling surfaces to resist nonspecific adsorption of proteins and other biomolecules. The interactions among zwitterionic groups have attracted considerable attention in bioengineering, whereas the understanding of their nanomechanical mechanism still remains limited. In this work, the interaction mechanisms between two zwitterionic groups with opposite dipoles, i.e., phosphorylcholine (PC) and sulfobetaine (SB), have been investigated via direct force measurements using an atomic force microscope (AFM) and dynamic adsorption tests using the quartz crystal microbalance with dissipation monitoring technique (QCM-D) in aqueous solutions. The AFM force measurements show that the adhesive forces between contacted zwitterionic surfaces during separation in both symmetric and asymmetric configurations were close, mainly due to the enforced alignment of opposing dipole pairs via complementary orientations under confinement. The solution salinity and pH had almost negligible influence on the adhesion measured during surface separation. The QCM-D adsorption tests of PC-headed lipid on PC and SB surfaces showed some degree of adsorption of lipid molecules on the SB surface, whereas not on the PC surface. The different adsorption behaviors indicate that because the outermost negatively charged sulfonic group on the SB faced the aqueous solution, this configuration could facilitate it to form an attractive electrostatic interaction with the PC head of lipid molecules in the solution. This work shows that in addition to hydration and steric interactions, the zwitterionic dipole-induced interactions play an important role in the adhesion and antifouling behaviors of the zwitterionic molecules and surfaces. The improved fundamental understanding provides useful insights into the development of new functional materials and coatings with antifouling applications.

The phytotoxicity of added copper (Cu) and nickel (Ni) is influenced by soil properties and field aging. However, the differences in the chemical behavior between Cu and Ni are still unclear. Therefore, this study was conducted to investigate the extractability of added Cu and Ni in 6-year field experiments, as well as the link with their phytotoxicity. The results showed that the extractability of added Cu decreased by 6.63% (5.10%–7.90%), 22.5% (20.6%–23.9%), and 6.87% (0%–17.9%) on average for acidic, neutral, and alkaline soil from 1 to 6 years, although the phytotoxicity of added Cu and Ni did not change significantly from 1 to 6 years in the long term field experiment. Because of dissolution of Cu, when the pH decreased below 7.0, the extractability of Cu in alkaline soil by EDTA at pH 4.0 could not reflect the effects of aging. For Ni, the extractability decreased by 18.1% (10.1%–33.0%), 63.0% (59.2%–68.8%), and 22.0% (12.4%–31.8%) from 1 to 6 years in acidic, neutral, and alkaline soils, respectively, indicating the effects of aging on Ni were greater than on Cu. The sum of ten sequential extractions of Cu and Ni showed that added Cu was more extractable than Ni in neutral and alkaline soil, but similar in acidic soil.

Metformin, one of the most widely used antidiabetic drugs, has recently been associated with potential antitumorigenic effects. In this study, we evaluated the possible cytotoxic impact of combined low doses of metformin and ionizing radiation (IR) on 2 human hepatoma cell lines. The cytotoxic effect of metformin combined with IR was subsequently determined by clonogenic survival and cell cycle assays, assessment of mitochondrial complex I and lactate dehydrogenase (LDH) activity, measurement of cellular adenosine triphosphate (ATP) levels, comet assay and analyses of the formation and disappearance of phosphorylated histone H2AX (γ-H2AX) protein. The combination of metformin and IR caused a much stronger cytotoxicity than the treatment with metformin or IR alone, leading to an ~80% decrease in cell viability and ~35% increase in the accumulation of cells in the G2/M phase of the cell cycle in the 2 hepatoma cell lines. In addition, a reduction in mitochondrial complex I activity (~70%) and a significant increase in LDH activity, as well as lactate production were observed in the cells exposed to metformin. Interestingly, a severe depletion in ATP, increased olive tail moment and the delayed disappearance of γ-H2AX expression were detected in the hepatoma cells treated by metformin plus IR. These findings show that the combination of a low concentration of metformin and IR results in the considerable enhancement of cytotoxic effects in human hepatoma cell lines, leading to decreased DNA repair by reducing ATP production. The data provided in this study may elucidate the remarkable efficiency of this combination treatment and suggest that metformin may be used as a potential adjunct to the radiotherapy of hepatocellular carcinoma.

Effective removal of ink particles by froth flotation is of up-most importance in paper recycling. In this study, the potential use of talc particles as carriers of difficult-to-float fine ink particles is investigated. In order to facilitate ink particle removal by carrier flotation, the interactions between talc and oily-ink particles in aqueous solutions containing flotation chemicals are studied by zeta potential distribution measurements and with the impinging jet apparatus. The chemical conditions under which talc–ink aggregation occurs are identified and reported.

We consider the response of a laser-induced quadrupole-dipole collisional system driven by a strong dressing laser field with the aim of calculating the collisional cross section of a weak inducing laser probe. The addition of a second driving field to the traditional arrangement will cause magnitude changes of the spectra and modify the profile. The calculation results show that the bichromatic laser-induced collisional energy-transfer process can be an efficient way to probe Stark splitting of both the final state and intermediate state. The magnitude and position of the splitting spectral lines are strongly dependent on the intensity of the dressing laser field. The peak cross section almost reduces by a factor of 2 with the presence of the dressing laser. Also, in the antistatic wing, bright and dark lines are periodic, appearing with the increasing of the dressing laser intensity.

A novel concept of reactive oily bubbles (i.e., bubbles covered by a thin layer of oil containing oil-soluble collectors) as a carrier in flotation is proposed. In addition to the role of fine particle agglomeration by oily films, the surface properties of air bubbles coated with a thin oil film can be better controlled for the desired selectivity by adding certain types and concentrations of water insoluble collectors into the oil phase. Oily bubbles attain a much higher contact angle than air bubbles, ensuring a strong collecting power, favorably for floating both coarse and fine particles. The reactive oily bubble flotation can eliminate the addition of collector to the aqueous phase, avoid undesired synergetic interactions among collectors, activators, depressants and dispersants present in slurry, minimize undesired activation of gangue particles and significantly reduce the amount of collectors needed. The electrokinetics of kerosene droplets in aqueous collector solutions was measured as a function of solution pH. The results clearly showed that the surface charge and hence the surface properties of oil droplets can be finely tuned by controlling the type of the collectors to suit the desired flotation needs. The attachment of collector-containing oily bubbles on silica, sphalerite and galena surfaces was investigated with contact angle measurement. The concept of using reactive oily bubble to achieve selective flotation was demonstrated in microflotation tests.

A novel technique to investigate the interactions between bitumen and clays in an aqueous solution from the measurement of zeta potential distributions is described. For a single component suspension (i.e., clay or bitumen), a single modal zeta potential distribution was obtained under a given solution condition. In the case of a two-component (i.e., bitumen and clay) mixture system, the measured zeta potential distribution showed either one or two distribution peaks, depending on the chemical condition of the suspension and the type/amount of clays present. In the absence of added calcium ions, a mixture of bitumen emulsion and clay suspension exhibited two distinct zeta potential distribution peaks, corresponding to the peaks measured individually for the bitumen and clays, respectively. With the addition of 1 mM calcium ions, however, only one zeta potential distribution peak was obtained for the mixture of bitumen emulsion and montmorillonite clay suspension. Depending on the montmorillonite clay to bitumen ratio, the peak position in this case shifted toward the value for montmorillonite clay suspension alone. For kaolinite, the addition of 1 mM calcium ions did not cause a substantial change in the bimodal zeta potential distribution. The results suggest qualitatively a stronger interaction of bitumen with montmorillonite clay than with kaolinite clay, when calcium ions were present. The slime coating of montmorillonite clay on bitumen droplets in the presence of 1 mM calcium was validated. The conclusions obtained from this study further justified our mechanistic hypothesis for the observed depression of bitumen flotation by montmorillonite but not by kaolinite clay addition when calcium ions were added. This study demonstrated that zeta potential distribution measurement could be a powerful tool to study slime coating phenomena in a complex colloidal system.

The relationships developed between soil properties and phytotoxicity threshold values for copper require validation in a wide range of soils with different properties and climate characteristics before they can be applied for regulatory purposes in countries throughout the world. Seventeen soils, which are representative of the major soil types and properties in China, were spiked with Cu chloride. A subset of the Cu-spiked soils was leached with artificial rain water to compare toxicity with that in unleached soils. Barley root elongation tests were performed under controlled environmental conditions. The concentrations of added Cu causing a 50% inhibitory effect (EC50) ranged from 67 to 1,129 mg/kg in unleached soils and from 88 to 1,255 mg/kg in leached soil. Compared with the unleached toxicity thresholds, the leached EC10 (10% inhibition) and EC50 were higher by an average of 1.43- and 1.15-fold, respectively. Soil leaching significantly (p

The laser performance of Pyrromethene 597 (PM597) and Rhodamine 610 mixture is studied. A wide tuning range from 580 to 655 nm is achieved. The laser linewidth obtained is less than 0.1 nm. The highest conversion efficiency of 42.5% is obtained at 600 nm. Using a beta-BaB2O4 (BBO) crystal to frequency double the dye laser into ultraviolet (UV), a tuning range from 296 to 324 nm is obtained. The peak conversion efficiency from the dye laser to the UV laser is 9.7% and the highest UV laser output energy is 9.51 mJ at 301.25 nm. To the best of our knowledge, the tuning range and the conversion efficiency are the best under the same condition so far. All our results indicate that high laser performance can be achieved using a laser dyes' mixture.