Suspended State Research Articles

Enhancing Quantum Dot LED Efficiency by Tuning Electron Mobility in the ZnO Electron Transport Layer

Quantum‐dot (QD) light‐emitting diodes (QLEDs) are an important new class of optoelectronic device. Despite the ubiquity of ZnO as the electron‐transport material in QLEDs, little is known about how its properties influence QLED performance. Here, it is demonstrated that the defect density and electron mobility of the ZnO nanoparticle electron‐transport layer strongly affect QLED device efficiency and can be used to balance electron and hole injection into the QD layer. Films of ZnO nanoparticles exhibiting electron mobilities tuneable over an order of magnitude are made by annealing out defect states in suspensions of ZnO nanoparticles prior to deposition. By incorporating these ZnO films into a typical QLED device, it is demonstrated that a clear maximum in QLED external quantum efficiency can be found at ZnO mobilities around 2–4 × 10−4 cm2 V−1 s−1, yielding over 10 000 cd m−2 at low operating voltage. The work demonstrates a simple method for enhancing QLED performance without modification of the device architecture and provides valuable insights into the physics of QLED operation.

The Suspension of Water Using a Superconductive Magnetic-Field and Its Features

The magnetization of water and its magnetism are experimentally researched and confirmed by virtue of the suspended method of magnetized water droplets in a superconductive magnetic field having a gradient distribution of strength with a maximum value of 16.12 T, generated by the superconductive Nb 3 Zn and NbTi coils. The experiments exhibit that the magnetized and purified water droplets are all suspended in the magnetic-field, the interaction of two suspended water droplets is also observed, and recorded by a camera. Based on these experimental results, we revealed and built the mechanism of suspension of magnetized water droplets using the theory of magnetism, i.e., the balance between the gravity of magnetized water droplet and the magnetic attraction force accepted by it arising from the superconductive magnetic field results in their suspension states. We explained the experimental results using this mechanism and have observed also that the suspended water droplets fall off the bottom of the sample tube if the electric current in the device is broken off. These results verified just the correctness of this mechanism of suspension. On the basis of the mechanism of suspension and these experimental results, we certified and affirmed that the magnetized waters have certain magnetism. This conclusion will promote the development of investigation of magnetized water and its application.

Where the Heart Is: The Concept of “Home” in Leila Aboulela’s Short Fiction

In most of her works, Leila Aboulela focuses on Sudanese characters in the diaspora. Her protagonists are usually young Sudanese migrants who had left home in search of a better life abroad, or to escape a desperate reality at home. In this journey, they live in a constant state of exile: the new abode fails to become home, and they are left existing in a state of suspension between the new reality and a past they are emotionally and spiritually stuck in. This paper tackles the concept of home in its actual and virtual manifestations through the lives of her short stories protagonists, their quest for one’s identity and keeping (or losing) it when confronting the other. The female characters are found to be more solid than their male counterparts in their nostalgia and attachment to the original home and its values. This enabled them to keep the fabric of their identity intact. When confronting the other, or when engaging in a relationship, “things do not fall apart” in this encounter. In fact, the other has to compromise to be accepted. This contrasts with the male characters, who are easily assimilated in the new environment, but not without a faint sense of guilt and a fair share of self-deception.

Global Identification of Biofilm-Specific Proteolysis in Candida albicans.

ABSTRACTCandida albicans is a fungal species that is part of the normal human microbiota and also an opportunistic pathogen capable of causing mucosal and systemic infections. C. albicans cells proliferate in a planktonic (suspension) state, but they also form biofilms, organized and tightly packed communities of cells attached to a solid surface. Biofilms colonize many niches of the human body and persist on implanted medical devices, where they are a major source of new C. albicans infections. Here, we used an unbiased and global substrate-profiling approach to discover proteolytic activities produced specifically by C. albicans biofilms, compared to planktonic cells, with the goal of identifying potential biofilm-specific diagnostic markers and targets for therapeutic intervention. This activity-based profiling approach, coupled with proteomics, identified Sap5 (Candidapepsin-5) and Sap6 (Candidapepsin-6) as major biofilm-specific proteases secreted by C. albicans. Fluorogenic peptide substrates with selectivity for Sap5 or Sap6 confirmed that their activities are highly upregulated in C. albicans biofilms; we also show that these activities are upregulated in other Candida clade pathogens. Deletion of the SAP5 and SAP6 genes in C. albicans compromised biofilm development in vitro in standard biofilm assays and in vivo in a rat central venous catheter biofilm model. This work establishes secreted proteolysis as a promising enzymatic marker and potential therapeutic target for Candida biofilm formation.

Comparison of the NH4+-N removal ability by Klebsiella sp. FC61 in a bacterial suspension system and a bacterial immobilization system

Abstract The aim of this study was to compare the removal of ammonia-nitrogen (NH 4 + -N) in a bacterial suspension system (BSS) and a bacterial immobilization system (BIS) using the iron-reducing bacterium Klebsiella sp. FC61. The experimental results showed that the pellets in the BIS could adsorb part of the iron ions in the solution. Although the adsorption of Fe 3+ was stronger than that of Fe 2+ , single-layer physical adsorption was observed in both cases. Furthermore, the self-inhibition effect of the bacteria from the suspended state to the immobilized state was effectively improved in the BIS, with a maximum NH 4 + -N removal rate (r max ) of 0.7241 mg/L/h for the BIS and 0.3732 mg/L/h for the BSS. Moreover, strain FC61 could effectively remove the NH 4 + -N in both the BIS and BSS, while maintaining a lower concentration of iron ions, nitrate, nitrite, and the quantity of microorganism in the solution. The results of response surface methodology showed that the predicted maximum removal ratio of NH 4 + -N in the BIS was 70.31% (actual value = 72.15%), which was higher than that of the BSS at 59.59% (actual value = 61.37%) at the same time point of 48 h. Analysis of bacterial distribution and growth data suggested that removal of NH 4 + -N by strain FC61 would be more favorable in the BIS than in the BSS.

Design, Fabrication, and Test of an HTS Magnetic Suspension Experimental System

Aiming at a number of disadvantages in the current normal-conductive electromagnetic suspension (EMS) system, particularly considerable energy consumption and high precision requirement for rail processing, this paper compared three types of suspension schemes, taking advantage of superconducting wire, i.e., electrodynamic suspension, hybrid suspension (HTS+EMS), and HTS EMS. An HTS magnetic suspension experimental system was designed and built on the basis of Bi-2223/Ag tape. A few of the concerns with respect to the HTS coils were discussed, including insulation, stabilization, current leads, fixation, and cooling condition. The 3-D simulation of electromagnetic field based on finite element analysis was executed to validate the theoretical design and parameter calculation of the HTS suspension electromagnet. In addition, some other major components of the experimental system were briefly introduced, i.e., sensors, digital signal processing control circuit, power amplifier, suspension program, and measuring instruments. In contrast to the previous preliminary test, a significant progress was that a superconducting and steady state of dynamic suspension had been successfully achieved when the experimental system was suffering from a larger alternating current in real-time control operation. The results of the suspension test would be of great reference value for the practical maglev train making use of the HTS EMS in the future.

Observer-based hybrid control algorithm for semi-active suspension systems

In order to improve ride comfort and handling performance of the vehicle, an adaptive hybrid control algorithm is proposed for semi-active suspension systems. The virtues of sky-hook is combined with ground-hook control strategies and a more suitable compromise for the suspension systems is chosen. The hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high speed conditions. Damping continuous adjustable absorber is used to continuously control the damping force so as to eliminate the damping force jerk instead of traditional on-off control policy. Based on suspension stroke measured by sensors, unscented Kalman filter is designed to estimate the suspension states in real-time for the realization of hybrid control, which improves the robustness of the control strategy and is adaptive to different types of road profiles. Finally, the proposed control algorithm is validated under the following two typical road profiles: half-sine speed bump road and the random road. The simulation results indicate that the hybrid control algorithm could offer a good coordination between ride comfort and handling of the vehicle.

Synchronized oscillations of dimers in biphasic charged fd-virus suspensions.

Micron-sized colloidal spheres that are dispersed in an isotropic-nematic biphasic host suspension of charged rods (fd-virus particles) are shown to spontaneously form dimers, which exhibit a synchronized oscillatory motion. Dimer formation is not observed in the monophase of isotropic and nematic suspensions. The synchronized oscillations of dimers are connected to the inhomogeneous state of the host suspension of charged rods (fdviruses) where nematic domains are in coexistence with isotropic regions. The synchronization of oscillations occurs in bulk states, in the absence of an external field. With a low field strength of an applied electric field, the synchronization is rather reduced, but it recovers again when the field is turned off. In this Rapid Communication, we report this observation as an example of the strange attractor, occurring in the mixture of PS (polystyrene) dimers in an isotropic-nematic coexistence biphasic fd-virus network. Furthermore, we highlight that the synchronization of PS-dimer oscillations is the result of a global bifurcation diagram, driven by a delicate balance between the short-attractive "twisted" interaction of PS dimers and long-ranged electrostatic repulsive interactions of charged fd rods. The interest is then in the local enhancement of "twist-nematic" elasticity in reorientation of the dimer oscillations. An analysis of image-time correlations is provided with the data movies and Fourier transforms of averaged orientations for the synchronized oscillations of dimers in the biphasic I-N coexistence concentration of charged fd-virus suspensions.

Effect of dispersants on the kinetics of asphaltene settling using turbidity measurement method

ABSTRACTOrganic deposition especially asphaltenes in reservoirs, wells, and equipment has a detrimental effect on petroleum economy. Generally, for chemically control of asphaltene precipitation using dispersants and inhibitors of precipitation or solvents of asphaltene is very common. Although asphaltene in crude oil is stable under specific conditions, but there is no assurance that the system will be stable and asphaltenes could be remaining in suspension state. In this study, the kinetic effects of three dispersants on stabilization of asphaltene aggregates were investigated by turbidity measurement method. Turbidity measurement showed as the dispersant strength rises, the turbidity of unstable sample containing dispersant less declines versus time. In order to carry out further studies on dispersants, the effect of dispersant on asphaltene particle size distribution was investigated. The results of asphaltene particle size distribution measurements showed that adding dispersant cause to decrease the volume percent of particles with medium diameter.

In situ assessment of carbon nanotube flow and filtration monitoring through glass fabric using electrical resistance measurement

Filtration of nanofillers into porous fabric media is still an issue during the preparation of advanced fiber-reinforced composites. The assessment of resin/multiwall carbon nanotube (MWCNT) flow, MWCNT filtration, and the cure monitoring of glass fiber/carbon nanotube-polyester composites by means of the measurement of the electrical resistance was introduced. The vacuum-assisted resin transfer molding technique was used. The electrical resistances measured over the span of a composite were qualitatively correlated with MWCNT flow and the degree of MWCNT filtration. It was found that while the complexity of the fabrics could likely introduce preferential deposition of MWCNTs, their filtration is mainly affected by their dispersion state in the resin suspension. Relationships among critical parameters such as the lengths and diameters of MWCNTs, the inter- and intra-tow dimensions of glass fabrics, the dispersion level of MWCNTs, and the viscosity of nanocomposite samples are discussed and correlated to the filtration, cure, and flow phenomena. We showed that our method can also serve as an early warning to obviate defects in the resulting composite.

Experimental simulation of chemistry transformation of anaerobic water during aeration

Experiments were carried out to simulate the transformations of anaerobic freshwater chemistry at aeration. Quantitative characteristics of the passage from dissolved into suspended state in the course of aeration were obtained for Fe, Mn, Co, Ni, Cu, Zn, Cd, Ag, Rb, Cs, Sr, Ba, Be, Al, Ga, Cr, Ti, Zr, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, B, V, Ge, As, Mo, and W. The decrease in the concentration of dissolved forms was found to be maximal for Fe and Mn, reaching 0.03 and 0.2 mg/L, respectively; these values correspond to the solubility of newly-precipitated oxihydrates of those elements. Among other elements, a high degree of removal is typical of elements-hydrolysates (Cr, Zr, Al, Ga, Be, Ti, and the majority of rare-earth elements), some heavy metals (Zn, Ag, Cd, and Co), and W.

Heat Transfer and Boiling Crisis at Droplets Evaporation of Ethanol Water Solution

Droplets evaporation and boiling crisis of ethanol water solution were studied experimentally. At intensive nucleate boiling within a droplet, most evaporation relates to an increase in the area of the wetting droplet surface and only 10–20% of evaporation relates to the effect of diffusion and a change in the thermal–physical coefficients. In alcohol solution with mass salt concentration C0 = 25–35%, maximal instability of the bubble microlayer is observed. The critical heat flux behaves nonmonotonously due to changes in mass alcohol concentration in the solution, and there are two extrema. The maximal value of sustainability coefficient at droplets evaporation of ethanol solution corresponds to C0 of 25–30%. The heat transfer coefficient of ethanol water solution of droplet in the suspended state decreases with a rise of wall overheating and spheroid diameter. Experimental dependence of the vapor layer height on wall overheating at boiling crisis was observed. The height of this layer at Leidenfrost temperature was many times higher than the surface microroughness value. The liquid–vapor interface oscillates, and this extends the transitional temperature zone associated with a droplet's boiling crisis.

Thermosensitive silica-pluronic-starch model coating dispersion-part I: The effect of Pluronic block copolymer adsorption on the colloidal stability and rheology

The colloidal stability of a model paper coating dispersion consisting of silica particles, Pluronic F127, starch and glycerol was studied with respect to PF127 temperature responsiveness and its adsorption on the silica surface. Rheological characterization of this system in order to extract structural information for the wet suspension state was accomplished in terms of rotational tests. The analysis, done by Krieger-Dougherty model and the elastic floc model for all flow curves at three different temperatures, 20°C, 25°C and 30°C, and at different particle volume fractions (Ͽ between 0 and 0.31), revealed that the structure of the system changes. Two regions with different behaviour and a plateau region at particle volume fraction of Ͽ⿼0.16 were observed. At Ͽ⿤0.16 temperature was affecting the suspension structure. By rising the temperature the well dispersed suspension at 20°C transformed to flocculated one, where the higher the temperature was, more open floc structures were detected in terms of degree of flocculation parameter, Cfp, but at the same time with increasing the particle concentration the flocs got denser according to the calculated. At Ͽ⿥0.16, there were not detected major structural differences by changing temperature or particle concentration. At Ͽ⿼0.16 a plateau in yield stress values was observed. The behaviour of the investigated model coating suspension was discussed in terms of shear stresses andCfp.

Solid nanoemulsion as antigen and immunopotentiator carrier for transcutaneous immunization

Imiquimod, a toll-like receptor 7 (TLR7) agonist, is an active pharmaceutical ingredient (API) established for the topical treatment of several dermal cancerous and precancerous skin lesions. Within this work, the immunostimulatory effect of imiquimod is further exploited in a transcutaneous immunization (TCI) approach based on a solid nanoemulsion (SN) formulation. SN contains a combination of imiquimod with the model peptide antigen SIINFEKL as a novel approach to omit needle and syringe and optimize dermal antigen administration.Excipients including sucrose fatty acid esters and the pharmaceutically acceptable oils MCT (middle chain triglycerides), avocado oil, jojoba wax and squalene are high pressure homogenized together with the antigen SIINFEKL. Freeze drying was performed to eliminate water and to achieve spreadable properties of the formulation for dermal administration. The influence of the different oil components was assessed regarding in vitro drug permeation in a Franz diffusion cell model using a murine skin setup. In vivo performance in terms of cytotoxic T-cell response was assessed in a C57BL/6 mouse model.Whereas Aldara® cream contains imiquimod in a dissolved state, the SN formulations carry the active in a suspended state. This resulted in a reduction of imiquimod permeation across murine skin from the SN when compared to Aldara® cream. In spite of this permeation rate reduction, each SN induced an in vivo immune response by specific T-cell lysis. A stabilized solid nanosuspension containing squalene/tocopherol exhibited a significantly higher performance (p⩽0.05) in comparison with Aldara® cream. MCT based SN exerted an in vivo effect comparable to Aldara®.In conclusion, anhydrous highly dispersed vehicles containing imiquimod in a submicron particle size distribution can represent promising formulations for TCI. The choice of the oil component has a strong influence on SN performance, independent of in vitro drug permeation.

Physiochemical characterization of taste masking levetiracetam ion exchange resinates in the solid state and formulation of stable liquid suspension for pediatric use

In the present work, an attempt has been made to mask the bitter taste of Levetiracetam using various ion-exchange resins such as Amberlite IRP69 and Duolite AP143. The physicochemical characteristics of the drug–resin complex in the solid state were studied. FT-IR studies revealed that there is no interaction between drug and resin. The DSC and XRD studies proved that the drug is in amorphous nature. Using the same concentration of resins, Xanthan gum as suspending agent in a liquid dosage form for pediatric use was formulated. Evaluation parameters such as drug content, sedimentation volume, re-dispersibility and viscosity of the prepared suspension were found to be satisfactory. The higher Zeta potential value indicates the stability of the suspension. Suspension prepared with Duolite AP 143 efficiently masks the bitter taste of Levetiracetam compared to Amberlite IRP69. From the in vitro drug release, a formulation with 1:2 ratios of resin has shown the maximum release at the end of 90 minutes. The sustained effect is due to one of the properties of the resin. The release profile follows zero order kinetics. The results obtained in this work show that drug–resin complexes effectively masked the bitter taste of Levetiracetam while liquid formulation provides an easier way to administer and to overcome problems with noncompliance of pediatrics.

Design of a novel installation device for a subsea production system

Subsea production systems (SPSs) have dominated the exploration of deep-sea oil and gas fields because of their economic superiority. SPS is a high-investment and high-risk technology. A floating installation device (FID) and an installation method for the SPS using this device were designed in this study. The device is made of buoyant materials, allowing both the SPS and the FID to be kept in a suspended state. Thus, the restriction caused by the great weight of the SPS can be avoided. The dynamic response of the chain system and FID was analysed according to environmental loads and material characteristics. The feasibility of the design was validated through numerical simulation and theoretical computation.

Decoupling the effects of screw speed and particle surface functionality on the filler suspension state in PBS/fumed silica nanocomposites

Decoupling the effects of screw speed and particle surface functionality on the filler suspension state in PBS/fumed silica nanocomposites

Pretreatment of bamboo by ultra-high pressure explosion with a high-pressure homogenizer for enzymatic hydrolysis and ethanol fermentation

Bamboo shoots, 2- and 5-year-old bamboo were treated by using a homogenizer in a constant suspended state, a process termed as ultra-high pressure explosion (UHPE). The bamboo powder was heated in 2% NaOH solution at 121°C, and then 100MPa UHPE-treated through a homogenizer. The results verified that UHPE changed the suspension solution of powder into a stick fluid. The contents of lignin were decreased significantly. The bamboo shoots and 2-year-old bamboo were completely hydrolyzed to glucose within 48h by enzymes loading of 15 FPU of cellulase and 30IU of β-glucosidase per gram glucan. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 89.7–95.1% of the theoretical ethanol yield after 24h. Therefore, NaOH+UHPE is argued to be a potential alternative technology for pretreatment of bamboo.

Accounts of Injury as Misappropriations of Race: Towards a Critical Black Politics of Vulnerability

Across contexts and time, subjects marked by racial difference have expressed public accounts of the multiple injuries of race. From the vantage point of critical race and black theory, this paper sheds light on both the heuristic and critical political values of such accounts. The first part critically reassesses conceptualizations of vulnerability as an ambivalent ontological condition within critical approaches to liberalism. A close reading of Fanon's account of injury in Black Skin, White Masks specifies how race exploits bodily and enunciative vulnerability and materializes subjects into a state of suspension and suspicion. The second part addresses the political promise of accounts of racialized injury. Departing from sceptical readings of “wounded attachment,” critical race and black analyses associate accounts of injury with citational practices that pertain to historically entrenched conventions of resistance to racial and colonial abusive power. Such accounts can be read as misappropriations of race which expand the horizon of the human.

Optimized methods for Legionella pneumophila release from its Acanthamoeba hosts.

BackgroundFree-living amoebae (FLA) and particularly acanthamoebae serve as vehicles and hosts for Legionella pneumophila, among other pathogenic microorganisms. Within the amoebae, L. pneumophila activates a complex regulatory pathway that enables the bacteria to resist amoebal digestion and to replicate. Moreover, the amoebae provide the bacteria protection against harsh environmental conditions and disinfectants commonly used in engineered water systems. To study this ecological relationship, co-culture and infection models have been used. However, there is a lack of data regarding the effectiveness of the different methods used to release intracellular bacteria from their amoebal hosts. The aim of this study was to evaluate the impact of the methods used to release intracellular L. pneumophila cells on the culturability of the bacteria. Furthermore, the standard method ISO 11731:1998 for the recovery and enumeration of Legionella from water samples was evaluated for its suitability to quantify intracellular bacteria.ResultsThe effectiveness of the eight release treatments applied to L. pneumophila and Acanthamoeba strains in a free-living state varied between bacterial strains. Moreover, the current study provides numerical data on the state of co-culture suspensions at different time points. The release treatments enhanced survival of both microorganisms in co-cultures of L. pneumophila and Acanthamoeba. Passage through a needle (21G, 27G) and centrifugation at 10,000 × g showed the highest bacterial counts when releasing the bacteria from the intracellular state. Regarding the ISO 11731:1998 method, one of the tested strains showed no differences between the recovery rates of associated and free-living L. pneumophila. However, a reduced bacterial recovery rate was observed for the second L. pneumophila strain used, and this difference is likely linked to the survival of the amoebae.ConclusionsMechanical release treatments were the most effective methods for providing bacterial release without the use of chemicals that could compromise further study of the intracellular bacteria. The current results demonstrated that the recovery of L. pneumophila from water systems may be underestimated if protozoal membranes are not disrupted.