Viscoelastic signature of physisorbed macromolecules at the solid–liquid interface

The covalent binding of proteins with polyethylene glycol (PEG) molecules is a valuable tool to extend the half-life of many biotherapeutics, including factor VIII (FVIII) products to treat patients with haemophilia A. Although PEG has low toxicity, accumulation of large PEG molecules (>20–30 kDa) with long-term exposure is a potential concern. Thus, it is important to determine whether sufficient excretion processes exist for PEG molecules used in biotherapeutics. BAY 94-9027 is an extended–half-life FVIII product modified through addition of a 60-kDa (branched: dual 30-kDa) PEG molecule. BAY 1025662 is the 60-kDa PEG moiety used for PEGylation of BAY 94-9027. This study investigated the pharmacokinetic (PK) properties, distribution, and excretion of BAY 1025662 in rats in order to predict estimated 60-kDa PEG PK properties in patients. Plasma concentrations in male rats after a single 11-mg/kg intravenous dose of BAY 1025662 (approximating the cumulative PEG-60 exposure in patients during 30 years of BAY 94-9027 treatment) decreased with an initial half-life of 119 h (5 days) in the interval of 114–336 h post administration. Single-dose mass balance studies using radiolabeled BAY 1025662 ([prop-14C]BAY 1025662) showed that 30.4% of radioactivity was excreted within 1 week and 79.1% by Day 168 (primarily in urine). The terminal half-life of radioactivity elimination was approximately 24 days in blood and plasma and was 31–68 days in the majority of other organs up to Day 168. Elimination was nearly complete at the end of the experiment on Day 168; only ~4% of residual radioactivity was present in the animal body. There was no irreversible binding of radioactivity to any tissues and no penetration of the blood-brain barrier. Based on these results, very low steady-state concentrations of 60-kDa PEG were predicted in patients treated with BAY 94-9027, and the validity of these predictions was supported by clinical studies in which almost all 179 patients receiving BAY 94-9027 for prophylaxis had undetectable PEG in plasma for up to >5 years; those with detectable PEG levels demonstrated concentrations within the predicted range. These combined preclinical and clinical observations suggest that excretion processes are in place for high-molecular-weight PEGs such as the PEG-60 moiety used in BAY 94-9027.

Physiology of soybean as affected by PEG-induced drought stress

In Chapter 3 we explored the properties of dry convective boundary layers that form when there is a positive buoyancy flux from the surface. Under a variety of conditions, such boundary layers become deep and/or moist enough that clouds form within them. When this happens, the properties of the boundary layer are strongly altered by the latent heat released and absorbed when water changes phase and by the very strong effect of clouds on radiative transfer. In this chapter we explore the properties of boundary layers strongly influenced by clouds that are shallow enough that little precipitation is formed. Boundary layers with clouds may be classified into four groups, illustrated in Figure 13.1: foggy layers, cloud-topped mixed layers, trade­ cumulus layers, and elevated stratocumulus/mixed trade cumulus-strato­cumulus layers. These are discussed in the following sections. Fog is defined as cloud in contact with the surface. For the present purposes, we exclude from this definition cloud in contact with hills or mountains. Over land, fog may form at night as a consequence of radiative cooling of the surface. Heat is lost from the air radiatively and diffused downward into the surface by wind-induced turbulence. If the air near the ground is cooled to its dew-point temperature, condensation occurs, first near the ground and later at higher altitudes. Initially, the fog is thickest near the surface, with the cloud-water content falling off rapidly with altitude. If it does not achieve a thickness greater than a few meters by sunrise, it will remain in this state until absorption of sunlight by the surface and by the cloud itself raises the temperature enough to evaporate the cloud. Thin fog of this kind is not convective, because the cooling occurs from below.

The study aimed to develop stable single-walled carbon nanotube (SWCNT) dispersions in water that exhibit low protein adsorption in biological media, entrap Memantine,and release the drug in a controlled manner. Specifically, SWCNTs were functionalized, initially oxidized, and then non-covalently conjugated with pyrene methoxy polyethylene glycols (PEG). Dynamic light scattering, Raman spectroscopy, and Fourier-transform infrared spectroscopy were used to evaluate various physicochemical properties of PEG functionalized SWCNTs (PEGSWCNTs). A D-optimal design, utilizing JMP Pro 16, was employed to design the experiment and investigate the effects of oxidation time and PEG concentration on the physicochemical properties of SWCNT dispersions. The optimal dispersions exhibited hydrodynamic particle sizes, polydispersity indices, and zeta potentials ranging from 157.5 to 204.4nm, 0.231 to 0.255, and -27.8 to -18.8mV, respectively. The interaction between serum proteins and PEGSWCNTs was evaluated using dynamic light scattering, bicinchoninic acid, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The serum protein-SWCNT interaction was significantly reduced due to the presence of PEGs, depending on PEG concentrations, the ratio of long-chain PEG molecules to short-chain PEG molecules, and the physicochemical properties of PEGSWCNT dispersions. Finally, Memantine was incorporated into the optimal PEGSWCNT dispersions. The entrapmentefficiency, drugloading, and drugrelease from the dispersions were evaluated using gas chromatography with flame ionization detection (GC/FID). The results indicated that PEGSWCNT particles could entrap Memantine. The in vitrodrug release profile exhibited an extended release over 3 to 7h, with a significant burst release occurring in the first hour (more than 50%). Higher PEG density and a higher PEG20K/2K ratio exhibited slower drug release rates. The release profiles of the formulations using 40% PEG were fitted to the Weibull model, indicating that Memantine release from the SWCNT dispersions followed a Fickian diffusion mechanism.

The purpose of this study was to explore the cryoprotection mechanisms of high molecular weight polyethylene glycols (PEGs) (eg, PEG 4000 and PEG 8000) on lactate dehydrogenase (LDH). Ultraviolet activity assays, circular dichroism (CD) spectroscopy, gel filtration, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), (14)C-PEG 4000 labeling and binding, and cryostage microscopic study were conducted. Different molecular weights and concentrations of PEGs in LDH formulations were treated by freeze-thawing. Higher molecular weights and concentrations of PEGs in LDH-PEG formulations obtained better activity and secondary structure recoveries of LDH after freeze-thawing. Insoluble aggregation of LDH was not observed in gel filtration studies. SDS-PAGE results suggested surface characteristic modifications of LDH by the larger molecular weight PEGs. The 14C-PEG 4000 labeling and binding study showed extensive nonspecific interactions between the PEG 4000 and LDH molecules in a concentration-dependent manner. The bound LDH-PEG 4000/free PEG 4000 ratio increased when LDH or PEG 4000 concentrations increased. Cryostage microscopic study showed that PEG 8000 delayed the ice crystallization and eutectic transition of LDH formulation. It appeared that multiple mechanisms were at work during PEGs' cryoprotection of LDH. It was unclear whether the delayed eutectic characteristics of PEGs contributed to LDH cryoprotection. The favorable interaction, rather than preferential exclusion, between LDH and PEGs (eg, 4000) cryoprotected LDH.

The molecular structures of polyethylene glycol (PEG) and chitosan (CS) are illustrated as follows: 1 CS 2 PEG The intermolecular interactions between these two polymers were studied by viscometry with a thermodynamic parameter α, which was first proposed by Sun et al. The weight additive rule of the intrinsic viscosity of polyblend relating to the values of each polymeric constituent was attested to with PEG/CS polyblend. The calculation formula of Huggins coefficient for polyblend, km, was theoretically deduced, and a very simple expression of α was obtained. First, the values of α for PEG/CS blends with different PEG molecular weight were estimated from the experimental viscosity data of the polyblends with different mixed ratio. According to these values of α, it can be predicted that an attractive interaction exists between the molecule of PEG and that of CS. Second, the viscosity of CS was measured in pseudo-solvents (PEG dissolved in 0.01N sodium chloride aqueous solution) with different PEG concentrations. From these viscosity data, the values of cross Huggins coefficient are calculated to be all larger than the values of the Huggins coefficient both for CS and for PEG. On the revised α criterion, the dissimilar molecular interaction in PEG/CS polyblend is demonstrated to be attractive too. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1275–1281, 1998

This work presents a laboratory study on the behavior of turbulent boundary layers over steep topographic elevations. Two main topics of interest are addressed here: (i) to investigate and characterize the separated flow region that is formed on the leeside of a steep elevation, and (ii) to evaluate the effects of flow stability conditions on the properties of boundary layers also subject to surface changes in elevation. To carry out this task, water channel and wind-tunnel investigations were conducted. For the former research topic, a neutrally stratified boundary layer was simulated in the water-channel of the Hydraulics Laboratory of FEUP. Mean and turbulent velocities were measured through laser-Doppler anemometry. Results provided a thorough description of the inner layers along the hill and inside the recirculation region. The refined near-wall data has contributed to the calculation of the friction velocity along the hill through different methods. For the latter topic, neutral, stable and unstable boundary layers were simulated in a wind-tunnel in the Laboratory of Turbulence Mechanics of COPPE/UFRJ. Simultaneous velocity and temperature fields were measured with the aid of thermal anemometry. These results allowed the characterization of the effects of the stratification on the speed-up factor, i.e. the maximum acceleration of the flow on hilltop. The present paper has introduced the concept of the heat up/down factor, in order to study the behaviour of the temperature field on the crest of the elevation.

Preferential hydration and solubility of proteins in aqueous solutions of polyethylene glycol

Reduction of the mechanical loss due to friction between two surfaces in motion is necessary to use natural energy resources effectively. A biomimetic bearing with ability of water sealing was proosed to expect the reduction of the mechanical loss for use in micro-&cluster-generation Systems as water power generators. The components of the bearing with sealing system has a rotating shaft sliding on the counterface made of polyvinyl formal (PVF) lubricated by polyethylene glycol (PEG) solution. The PVF which has hydrophilic and coutinuous porous structure promotes the elastohydrodynamic lubrication and weeping lubrication that are observed within synovial joint. In this report, durabillity of the bearing is discussed. The PVF material with porous diameters of 700 μm was adopted for the counterface material for a rotating shaft of 20 rpm. A load of 100 N was applied perpendicularly to the housing of bearing system. Two PEG solutions, one of molecular weight 2 million and the other a mixture of 0.5 and 0.02 million, were adopted as lubricating liquids. A tensile test was carried out after the friction test. A PEG solution with a molecular weight of 2 million produced a much lower coefficient of friction when compaired to the mixed solution. The maximum tensile force of PVF did not change after the friction test, but the elastic modulus increased in comparison with that which was assessed before the frictional test. It is shown that the PVF bearing with a excellent duability for sliding distances as high as 25,000 m, and that the molecular chains of PVFs might orientate to frictional direction.

BackgroundType-1 Interferons (IFN) are known to elicit both direct antitumor effects as well as modulate tumor microenvironment (TME) to induce antitumor immune responses. Combination of IFNa with PD-1 blockade has...

Similarity considerations are carried out and order of magnitude calculations to show that the characteristics of high Reynolds numberReynolds number flows are boundary layers. They are characterized by the convective transport of flow properties in the flow direction and diffusive transport in the cross-flow direction. The boundary-layer forms of the basic fluid flow equations are derived and are solved for wall boundary-layer flows. The Blasius form and the von Mises form of the boundary-layer equation are presented and their solutions are explained. TheBoundary conditionsBlasius solution Blasius solutionBlasius solution is elaborated and integral properties of the Blasius wall boundary layer are derived. The boundary-layer thicknessBoundary layer thickness is introduced, and also the displacement thicknessDisplacement thickness and the momentum loss thicknessBoundary layer thickness. Boundary-layer solutions are also presented for a laminar, two-dimensional free jetFlowsjet and the corresponding freeFlowswake wake flowFree wake flow.

The aim of this work is to study the effect of polyethylene glycol (PEG) on the modification of microstructure formation correlated with the mechanical strength properties of perovskite-based membrane in form of a flat sheet. LSCF 7328 flat membrane was potentially promoted as an oxygen separator and catalyst for partial oxidation of methane reaction at high temperature. In this study, the phase-inversion followed by sintering process was used as the membrane fabrication method using varied PEG concentration of 0.55, 1.00, and 3.00 wt% with different molecular weight, i.e., PEG 300, 600, 1500, and 4000 Da for each PEG concentration. The result of morphology observation shows that almost every membrane hasthe asymmetric structure with finger-like pores and thin dense layer. Increasing PEG concentration as well as molecular weight increases pore size and affects on porosity, pore's volume, and physical properties of membrane. The largest pore size, pore volume and porosity of the membrane after sintering were found in the addition of 3.00% PEG 4000 (Da) additive with the value of 110.45 μm, 81.34 ml.g-1 and 120.6%, respectively. In addition, the mechanical properties of membrane were tested using the Vickers micro hardness method with the greatest value found in the addition of 3.00% PEG 1500 (Da) additive with the value of 13.58 Hv and the lowest is 3.00% PEG 4000 (Da) with the value of 1.2 Hv.

Efficacy and safety of sodium phosphate tablets compared with PEG solution in colon cleansing: Two identically designed, randomized, controlled, parallel group, multicenter phase III trials

The adsorption kinetics of polyethylene glycol (PEG) during Cu electroless deposition was investigated in real-time by measuring the open-circuit potential (OCP) and mass change of a Cu electrode. The addition of PEG during the deposition caused an OCP decrease with a reduction in the deposition rate. It was found that the adsorption of PEG blocked active sites for the adsorption of formaldehyde, a reducing agent, resulting in the suppression effect. The adsorption kinetics of PEG was strongly dependent on the concentration and diffusion coefficient which is directly related to the molecular weight of PEG. The diffusion-controlled adsorption was observed when PEG concentration was low. At high PEG concentrations, the adsorption kinetics was adsorption-controlled when the PEG molecular weight was low and diffusion-controlled when the PEG had a high molecular weight. The strength of the suppression effect was also affected by the molecular weight of PEG: increasing the molecular weight enhanced the suppression effect.

Abstract