Strength Of Medium Research Articles

A comparative study of methylamines synthesis over zeolites H-rho and H-PST-29

A comparative study was performed not only on the proton form of rho and PST-29, the first and second generations of the RHO family of embedded isoreticular zeolites, respectively, but also on their steam-dealuminated analogues, as catalysts for methylamines synthesis at 400 °C from ammonia and methanol. A similar yield in the sum of monomethylamine plus dimethylamine was observed for H-rho and H-PST-29. Steam treatment at 600 °C gave both zeolites an increase in catalyst lifetime, but which is much more apparent in H-PST-29, probably due to a larger decrease in strength of medium and strong acid sites, together with the mesopore formation. Dealumianted PST-29 showed a somewhat lower catalyst stability than H-mordenite, the former commercial catalyst for this reaction. However, it was found to exhibit a much higher yield in smaller methylamines and a comparable regenerability. • H-rho, H-PST-29, and their steam analogues are tested for methylamines synthesis. • H-PST-29 showed a similar yield in monomethylamine plus dimethylamine to H-rho. • Steaming of H-rho and H-PST-29 resulted in an increase in the catalytic lifetimes. • The steamed PST-29 is potentially useful as a catalyst in methylamines synthesis.

Complexation of a cationic pyrene derivative with sulfobutylether substituted β-cyclodextrin: Towards a stimulus-responsive supramolecular material

Abstract The self-aggregation of the aggregation prone molecules are avoided by employing a macrocyclic host molecule, such as β-cyclodextrin, which commonly favours the inclusion complex formation with the guest molecule and prevents the self-aggregation of the guest molecule. On the contrary, the substituted host molecules, with multiple charges are reported to promote self-aggregation of guest molecules, specifically when the guest molecules are oppositely charged. One such interesting anionic host molecule is sulfobutylether substituted β-cyclodextrin (SBE7-β-CD), which possesses both extended hydrophobic cavity as well as relatively high negative charge which makes this host capable of forming both stable inclusion complexes with the incoming guest molecule as well as inducing aggregation of guest molecules. However, there are only limited reports of this host inducing aggregation of guest molecules. In the present work, we report the interaction of SBE7-β-CD with a versatile cationic fluorescent probe, 1-pyrenemethyl amine (PMA), using ground-state absorption, steady-state emission, and time-resolved emission measurements. Interestingly, in contrast to various reports, SBE7-β-CD is found to promote the aggregation of PMA molecules. These aggregates are confirmed by the changes in the emission spectra of PMA by emergence of a distinct broad emission band at around 493 nm, which is largely red-shifted from the monomer emission peaks of PMA which appear at 375 and 395 nm. The detailed investigation of the photophysical properties of this assembly discloses that association of PMA molecules in their ground-state is induced by SBE7-β-CD instead of forming excimers in the excited state. These aggregates are found to show significant and reversible response to external stimuli such as ionic strength of medium and temperature, which makes this system to be responsive aggregate assembly to be explored in sensing applications of biochemically important analytes, which has been demonstrated by sensing Lysine and Arginine, important basic amino acids, using this PMA-SBE7-β-CD assembly.

Effect of Non-Uniformity of Electric Field on Breakdown Strength of Cryogenic Gaseous Insulation Media for Superconducting Power Applications

A new experimental set up for measuring the breakdown strength of gas media in weakly non-uniform electric field at cryogenic temperatures and high pressures is described. Measure of breakdown strength of helium gas at 77 K and 293 K in a non-uniform electric field with a field efficiency factor 62.5% are presented. The results suggest that the breakdown strength in weakly non-uniform electric field relate to that of uniform electric field by the field efficiency factor, η. This relationship holds good for both 293 K and 77 K data. This observation expands our previously reported systematics of dielectric strength in uniform electric field to the weakly non-uniform electric field conditions, which is important for designing HTS power applications. The established relationship eliminates the need for costly experiments for measuring the dielectric strength at a specific operating temperature and pressure and in the required non-uniformity of the electric field.

Investigation of Within-Tablet Dynamics for Extended Release of a Poorly Soluble Basic Drug from Hydrophilic Matrix Tablets Using ATR-FTIR Imaging.

Hydrophilic matrices are an effective option for oral controlled release but can face challenges in terms of bioavailability and efficacy when used in conjunction with poorly soluble, weakly basic drugs. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) imaging provides dynamic information relating to the location and chemical nature of both the sustained release matrix and the active pharmaceutical ingredient (API) during hydration/dissolution. In this study, we have identified a model system combining itraconazole (IT), a poorly soluble, weakly basic API that has pKa in the physiological range, and hydroxypropyl methylcellulose, which is a commonly used oral tablet matrix. This system was investigated to determine the swelling kinetics at different pH values at a fixed ionic strength and to facilitate the study of the influence of hydrating media pH on the drug particle movement (translocation). Using ATR-FTIR imaging, we were able to show that gel layer formation and swelling were independent of pH but highly dependent on the ionic strength of the hydrating medium in placebo tablets. When the ionic strength was fixed, gel layer formation and radial swelling were both shown to be pH-dependent when IT was incorporated into the matrix. This was verified using optical imaging. The chemical specificity of ATR-FTIR imaging permitted the observation of transformational changes of IT from the free base to the ionized form in the tablet core during hydration. This phenomenon was shown to be greater at pH 1.5 than at pH 7. ATR-FTIR imaging was able to follow drug particle translocation at both pH 1.5 and pH 7; however, the extent of migration away from the tablet core was shown to be greater at lower pH. The location of the translocated particles within the gel layer was different between the two studied pH values, with particles being located close to the swelling front at pH 7 and within the diffusion front at pH 1.5. In both pH environments, the translocated IT particles were shown to be predominantly in the free base form. No evidence of fully solubilized IT was observed in the surrounding medium because of the inherent aqueous solubility of IT being below the instrument detection limits. This work highlighted the value of utilizing a chemically specific spectroscopic tool to increase the understanding of the nature of the factors affecting the release of a pH-dependent, poorly soluble drug from a hydrophilic matrix at different pH values and permitted greater insights into what happens inside the polymer matrix during drug release.

Influence of Culture Parameters on Phenolics, Flavonoids and Antioxidant Activity in Cell Culture Extracts of Date Palm (Phoenix dactylifera L.)

Natural compounds are a major source for pharmaceutical industries. Cell suspension culture provides a reliable method to enhance the productivity of compounds exhibiting antioxidant properties. In the present study, cell cultures of date palm (Phoenix dactylifera L.), a desert fruit species rich in nutrients and medicinal compounds, were grown in different culture parameters to determine the optimum conditions for culture growth and accumulation of active compounds. The tested parameters included MS strength of culture medium, sucrose concentration (1–8%), pH (4–6.5), inoculum density (1–20 g/l) carbohydrates (3%) and their combinations (sucrose, glucose, fructose and maltose) and different media (MS, B5, N6 and NN). The response to these parameters was assessed in terms of packed cell volume (PCV), total phenolic, flavonoid and antioxidant activity. The results showed the MS medium containing 3% sucrose at pH 5.8 enhanced the PCV production. Inoculum density of 5 g/l induced maximum flavonoid content in cell culture. The highest phenolic accumulation and antioxidant activity were observed in cell cultures grown in double-strength MS medium, 20 g/l inoculum density and 4% sucrose at pH 6. A positive correlation was detected between phenolic content and antioxidant activity. These findings can facilitate the scale-up production of pharmaceutically important compounds from date palm cell culture.

On the Mechanism of Bilayer Separation by Extrusion; or, Why Your Large Unilamellar Vesicles are Not Really Unilamellar

ABSTRACT Extrusion through porous filters is a widely used method for preparing biomimetic model membranes. Of primary importance in this approach is the efficient production of single bilayer (unilamellar) vesicles that eliminate the influence of interlamellar interactions and strictly define the bilayer surface area available to external reagents such as proteins. Sub-microscopic vesicles produced using extrusion are widely assumed to be unilamellar, and large deviations from this assumption would dramatically impact interpretations from many model membrane experiments. Using three probe-free methods—small-angle X-ray and neutron scattering (SAXS and SANS) and cryogenic electron microscopy (cryoEM)—we report unambiguous evidence of extensive multilamellarity in extruded vesicles composed of neutral phosphatidylcholine lipids, including for the common case of neutral lipids dispersed in physiological buffer and extruded through 100 nm diameter pores. In such preparations, only ~35% of lipids are externally accessible, and this fraction is highly dependent on preparation conditions. Charged lipids promote unilamellarity, as does decreasing solvent ionic strength, indicating the importance of electrostatic interactions in determining the lamellarity of extruded vesicles. Smaller extrusion pore sizes also robustly increase the fraction of unilamellar vesicles, suggesting a role for membrane bending. Taken together, these observations suggest a mechanistic model for extrusion, wherein formation of unilamellar vesicles involves competition between bilayer bending and adhesion energies. The findings presented here have wide-ranging implications for the design and interpretation of model membrane studies, especially ensemble-averaged observations relying on the assumption of unilamellarity. STATEMENT OF SIGNIFICANCE Extruded vesicles are a ubiquitous tool in membrane research. It is widely presumed that extrusion produces unilamellar (i.e., single bilayer) vesicles, an assumption that is often crucial for data analysis and interpretation. Using X-ray and neutron scattering and cryogenic electron microscopy, we show that a substantial amount of lipid remains inaccessible after extrusion due to an abundance of multilamellar vesicles (MLVs). While this is a general phenomenon for neutral lipids, MLV contamination can be reduced by several complementary approaches such as including charged lipids in the mixture, reducing the ionic strength of the aqueous medium, and reducing the extrusion pore size. These observations together suggest a mechanism by which extrusion strips MLVs of their layers.

Global Impact of Social Media on Women in Surgery

The professional use of social media is increasingly prevalent today, particularly in medicine and surgery. Several recent movements have highlighted the strengths of this forum for networking and mentorship for females in surgery who otherwise may lack mentors locally. We sought to describe modern uses for and strengths of social media for women in surgery globally via a systematic review of the literature. Multiple efforts and avenues have promoted gender equality in surgery, while also uniting female surgeons in a collaborative virtual network of colleagues. In particular, movements on Twitter, such as #ILookLikeASurgeon and #NYerORCoverChallenge, as well as other collaborative virtual fora have brought visibility to female surgeons, while drawing the young population of students and trainees toward surgical careers. Social media provides a unique opportunity for female trainees and established surgeons alike to network and establish mentorship relationships, which may aid in fostering interest in surgery and closing the gender gap in our field.

Augmented Reality as Potential Alternative Media for Paperless Advertising

Today we life in the era of technology and information. Technology has become an important tools in human daily need and being used in every field of works, including advertisement. With the rapid development of technology, information can be accessed easily in faster speed and in higher quantity. In advertising, information is one of the most important element, we want our advertisement to contain information about our products and delivered in a fastest pace as possible with enough attraction element in it, also we want our advertisement to reach as many people as possible. Ironically, in the era of technology, we still using papers in our advertisement like posters, brochures, booklets, and many other printed promotional tools. The high demand for papers gives negative impact for nature, not only for the trees and forest, but also for the ecosystem. The rapid development of technology has given us so many new alternatives media in advertising, one of them is augmented reality. Augmented reality have a lot of potential to use in many fields of works including advertising. This study attempts to give comparisons between conventional media and Augmented Reality in advertising. The interesting thing of this study is to learn the weakness and the strength of paper media and Augmented Reality in advertising, and to learn how technology can be used indirectly for preserving nature.

The synergistic toxicity of Cd(II) and Cu(II) to zebrafish (Danio rerio): Effect of water hardness

We have evaluated the interactive toxicity of Cu(II) and Cd(II) in water with different hardness levels using adult zebrafish (Danio rerio). Zebrafish were exposed to Cd(II) (0.2–22 μM) or Cu(II) (0.1–8 μM) in single or binary exposures in very soft, moderately hard or very hard water. The whole body burdens of Cd(II) and Cu(II) reflect the net effect of biouptake and elimination, mortality was the indicator of toxicity, and whole body major ion content was measured to assess ion regulatory functions. Cu(II) was found to be more toxic than Cd(II) for zebrafish, and Cu(II) and Cd(II) exhibited a significant synergistic effect. The toxicity of metal ions increased upon decreasing the ionic strength of the exposure medium, probably due to elevated competition between metal ions with other cations in hard water and increased activity of Ca2+ pathways in soft water treatments. Whole body metal accumulation and the accumulation rate of both Cu and Cd increased as the metal ion concentration in the exposure medium increased. Nevertheless, neither parameter explained the observed synergistic effect on mortality. Finally, we observed a significant loss of whole body Na+ in fish which died during the metal exposure compared to surviving fish, irrespective of exposure conditions. Such an effect was not observed for other major cations (K+, Ca2+ and Mg2+). This observation suggests that, under the applied exposure conditions, survival was correlated to the capacity of the organism to maintain Na+ homeostasis.

Assessing Drug Release from Manipulated Abuse Deterrent Formulations.

There is a need to develop in vitro dissolution methods that discriminate for particle size of the manipulated abuse deterrent formulation (ADF) and that can be used for in vivo predictive models since dissolution methods developed for intact formulation might not be suitable for manipulated ones. A vertical diffusion cell (VDC) and United States Pharmacopeia (USP) Apparatus 1, 2, and 4 were evaluated for measuring the dissolution of intact and manipulated metoprolol succinate tablets with abuse deterrent-like properties. These tablets were physically manipulated to produce fine (106-500μm) and coarse (500-1000μm) powder samples. The VDC method was not able to discriminate the effect of particle size on drug release with varied stirring rate (200 to 800rpm), molecular weight cut-off (MWCO, 3-5kDa to 12-14kDa) of the diffusion membrane, or composition and ionic strength (0.45% and 0.9%) of receiver medium. Standard and modified USP Apparatus 1 and 2 methods were assessed; however, large variations (RSD > 20%) were observed with USP Apparatus 1 for manipulated product dissolution and floating powder samples caused failure of auto-sampling when using standard USP Apparatus 2. For the USP Apparatus 4 dissolution method, packing configuration (1, 3, 8 layers and blend), ionic strength of dissolution medium (0.017, 0.077, and 0.154M additional NaCl), and flow rate (4, 8, 16mL/min) were studied to discriminate the effect of particle size on release. The USP Apparatus 4 dissolution method was optimized by using a packaging configuration of 8 layers with 8mL/min flow rate which exhibited low variability and complete drug release and it could be used for in vivo predictive models. The dissolution method variables can be optimized for a specific product for desirable reproducibility and discriminatory power when using USP Apparatus 4.

Improving the method for determining the granular media strength performance by oblique shear test

To ensure the strength performance of the pavement of open pit truck roads, it is necessary that it conforms not only to the designed required deformation (elasticity) modulus, but also to the condition for ensuring the shear resistance of structural layers made from non-cohesive and lowly cohesive granular media. However, today there are no reliable methods for determining the strength performance of coarse-grained materials, therefore, for them there are no designstrength values, and therefore their shear resistance is not evaluated, which is a serious omission. It is proposed to evaluate the strength performance of granular media by the oblique sheartest, for which an improved design of oblique shear apparatus was developed, which made it possible to adjust the granular medium density (structure) to the corresponding density (structure) under construction conditions. An analysis was also made of the influence of the angle of inclination of the shear area on the predicted values of normal and shear stresses arising in the cross section, which made it possible to establish the recommended values of this indicator depending on the prevailing particle size of the test medium.

Triggering mechanism and reactivation probability of loess-mudstone landslides induced by rainfall infiltration: a case study in Qinghai Province, Northwestern China

Rainfall, especially rainstorm, is a major factor in inducing loess-mudstone landslides and plays an essential role in landslide reactivation. The aim of the paper is to study the triggering mechanism and reactivation probability of a loess-mudstone landslide induced by rainfall infiltration in Qinghai Province, Northwestern China. According to the numerical model of elastic–plastic mechanics, the triggering mechanism of loess-mudstone landslides was revealed. Then, the reactivation probability of the potential landslide was evaluated by the combination of the limit equilibrium and Monte-Carlo methods. For one thing, the relationship between water content and shear strength of media was analyzed based on the mechanical test of materials. For another, the effects of rainfall conditions were analyzed on the distribution of water content in the aerated zone with the two-dimensional coupling model of unsaturated–saturated seepage. The results show that the shear strength of media is very sensitive to water content because of water–rock interaction including hydration and dissolution. Besides, the water content significantly increases at the interface between the loess and mudstone after the rainstorm occurring owing to the permeability heterogeneous of media and topographic feature, which leads to the strength deterioration. Although the whole landslide is stable in the rainstorm conditions, its middle part can be reactivated along the original sliding zone with high probability by a geomechanical model of sliding-tension. Therefore, the landslide reactivation is controlled by the water sensitivity of media, the permeability heterogeneous of media, the topographic feature and the original sliding zone, especially the original sliding zone. This research provides a valuable reference for the occurrence and reactivation of similar landslides.

Hydrogels from xylan/chitosan complexes for the controlled release of diclofenac sodium

Hydrogels were prepared from colloidal suspensions of polyelectrolyte complexes of xylan (Xyl) and chitosan (Ch) (mass ratio: 70 wt% Xyl/30 wt% Ch). They were formed at pH 5.0, at which both polyelectrolytes were highly charged according to their corresponding potentiometric titrations. They were treated with a polycarboxylic acid, sodium citrate, at different concentrations (0%, 3% and 7% w/v), and characterized by means of FTIR, scanning electron microscopy, wet-mechanical properties, swelling and solubility. FTIR spectra confirmed the presence of sodium citrate in the treated hydrogels. Wet-stress and wet-strain at break were increased by 150% and 57% respectively, when hydrogels were treated with 7% w/v of sodium citrate. The swelling capacity was clearly modified due to the presence of this compound and to the ionic strength of the liquid medium. The ability of these hydrogels for drug loading and controlled release was studied in vitro using diclofenac sodium (DS) as model drug. It was found that at pH 7.4, the hydrogel treated with sodium citrate absorbed significantly higher amounts of diclofenac sodium (up to 255 mg DS/g hydrogel) and its release was better controlled compared to that of the non-treated hydrogel. Particularly, the presence of sodium citrate in the liquid medium after the diclofenac sodium loading process and the influence of the ionic strength on the drug release rate indicated that an ion exchange process occurred, first between sodium citrate and diclofenac sodium and then between this drug and the ions present in the solution.

Root cap size and shape influence responses to the physical strength of the growth medium in Arabidopsis thaliana primary roots.

During the progression of root in soil, root cap cells are the first to encounter obstacles and are known to sense environmental cues, thus making the root cap a potential mechanosensing site. In this study, a two-layered growth medium system was developed in order to study root responses to variations in the physical strength of the medium and the importance of the root cap in the establishment of these responses. Root growth and trajectory of primary roots of Arabidopsis seedlings were investigated using in vivo image analysis. After contact with the harder layer of the medium, the root either penetrated it or underwent rapid curvature, thus enabling reorientation of growth. We initially hypothesized that the root-cap structure would affect apex penetration and reorientation, with pointed caps facilitating and domed caps impeding root penetration. This hypothesis was investigated by analysing the responses of Arabidopsis mutants with altered root caps. The primary root of lines of the fez-2 mutant, which has fewer root-cap cell layers and a more pointed root cap than wild-type roots, showed impaired penetration ability. Conversely, smb-3 roots, which display a rectangular-shaped cap, showed enhanced penetration abilities. These results, which contradict our original hypothesis, reveal a role for resistance to buckling in determining root penetration abilities.

Effects of glucose-glycine melanoidins on the digestive trypsin-like activity of the rainbow trout Oncorhynchus mykiss

Melanoidins, a product of advanced browning reactions due to the thermal treatment of the diet, has been previously demonstrated to inhibit the activity of trypsins from mammalian origin, but no data exists in relation to fish trypsins. The present work is devoted to the investigation of the effects of glucose-glycine melanoidins on the trypsin-like activity contained in intestinal crude extracts (ECIs) prepared from juvenile individuals of the rainbow trout Oncorhynchus mykiss. A turbidity assay was conducted to test for the existence of precipitation or aggregation phenomena in mixtures of ECIs and melanoidins, but no consequences were observed. Three experiments were conducted to test for the effects on the trypsin-like activity on the hydrolysis of the substrate BAEE (Nα-Benzoyl-L-arginine ethyl ester). Glucose-glycine melanoidins can inhibit the intestinal trypsin-like activity of the rainbow trout, but the effect is modulated by the pH and ionic strength of the reaction medium. The inhibition dropped when the pH was changed from 7.5 to 8.5, also when the ionic strength of the buffer was raised from 40 to 140 mM, while it was undetected at 180 mM. It is concluded that the effect of this type of melanoidins on the trypsin-like activity from the rainbow trout is probably low in the ionic conditions prevailing in the intestine of this species.

RAPID PROTOCOL OF Aloe vera In Vitro propagation

The current research was carried out to enhance Aloe vera propagation via tissue culture technique. BA at 0, 1, 2, 3, and 4 mg/l alone or combined with 0.1 mg/l NAA were used for shoot proliferation. The best result was recorded by using 2mgl-1 BAP (5.33 shoots/ explant). Meanwhile, combination between 2 mg/l BAP with (0.2, 0.4 and 0.6) mg/l kinetin, NAA or IBA were tested and best protocol was shown by using 2 mg1-1 BAP + 0.6 NAA which recorded 4.89 shoots/ explant. For rooting, MS medium at half and full strength salts were used supplemented with 0, 1, 2, 3, 4mgl-1 of NAA. The result revealed that 3 mg1-1 NAA at half strength of MS medium regenerate developed roots (8.67 roots / shoot) within 4 weeks. The well successful healthy plantlets were transferred into a potting mix composed of sand and peat moss which shows 100% survival ratio.

Effect of Media Strength and pH on the Growth of Hairy Roots and Production of Gymnemic Acid from Gymnema Sylvestre

Gymnema sylvestre (Madhunashini) is one of the most important medicinal plants used as a crude drug for its preventive and therapeutic properties. Among other constituents of Gymnema, gymnemic acid is a major component responsible for biological and pharmacological actions. The present study deals with the influence of different media strength and initial medium pH on the growth of hairy roots and gymnemic acid production from Gymnema sylvestre. Higher strength of the media (1.5X) favoured the biomass production (114.64 g/L FW and 12.63 g/L DW) and gymnemic acid content (11.7 mg/g DW) in the tested range of 0.25, 0.50, 0.75, 1.0, 1.5 and 2.0 X strength. Among the different hydrogen ion concentration (pH) of 4.0, 4.5, 5.0, 5.5, 5.8, 6.0 and 6.5, initial medium pH of 6.0 favoured the biomass production (102.41 g/L FW and 11.52 g/L DW) and medium pH of 5.8 favoured the gymnemic acid production (11.30 mg/g DW).

Versatile Paschen's model for the dielectric strength estimation of binary and ternary gas mixtures

The dielectric strength of various binary and ternary gas mixtures is accurately estimated by using the proposed versatile Paschen's model. Unlike the conventional Paschen's models, the new model is based on the improved regression process of the ionization coefficients that results in enhanced accuracy in the dielectric strength estimations of pure gases as well as binary and ternary gas mixtures. Compared to the conventional models, the dielectric strength values estimated by the proposed model and the experimental breakdown measurements show more close and consistent agreement. The results confirm the effectiveness, versatility, and veracity of the proposed Paschen's model in estimating the dielectric strength of gas media.

Transport of arsenic loaded by ferric humate colloid in saturated porous media

The transport behavior of arsenic (As(V)) loaded by ferric humate (HA-Fe) colloid, denoted as HA-Fe/As(V), moving in a saturated quartz sand column, was tested in the laboratory under varying pH values, ionic strengths, and HA and Fe(III) content. The time-fractional advection-dispersion equation (fADE) model was then employed to analyze the observed migration of HA-Fe/As(V). Results showed that the stability of the HA-Fe colloid exhibited an upward trend with an increasing pH and HA content. An increasing HA content led to a decrease in the particle size of the HA-Fe colloid. However, the effect of Fe(III) concentration on colloidal particle size exhibited the opposite phenomenon. The ability of the HA-Fe colloid to load As(V) gradually increased with the increase of the Fe(III) concentration. During the co-transport of the HA-Fe/As(V) colloid, transport of As(V) was promoted with increasing pH, increasing HA and Fe(III) content, and decreasing ionic strength in the saturated porous medium. The transport behavior of As(V) can be well fitted by the fADE model. The model analysis revealed that sub-diffusion of As(V) was weakened in the HA-Fe/As(V) colloid with high HA content. Sub-diffusion of As(V) in the low pH colloid was stronger than that of the high-pH colloid, and the molecular diffusion and mechanical dispersion were more weakened in the high-pH colloid than that of the low-pH colloid. When observing varying ionic strengths, As(V) exhibited stronger sub-diffusion in the HA-Fe/As(V) colloid with a higher ionic strength. As for the Fe(III) content, transport of As(V) was mainly affected by sub-diffusion in the HA-Fe/As(V) colloid with a low Fe(III) content. These findings provided direct and necessary insights into the effects of the HA-Fe colloid on the migration of As(V) throughout saturated porous media under different hydrochemical conditions found in natural environments.

Tertiary blends of PAMAM/PEG/PEG tissue bioadhesives

Lack of wet adhesion and biomechanical mismatch at tissue interfaces are the major challenges related to surgical adhesive formulations. Carbene-based bioadhesives seek to address those limitations, due to their ability to covalently bond to wet tissue surfaces. Herein, diazirine-grafted polyamidoamine (PAMAM) dendrimers (PDz) dissolved in various liquid polyethylene glycols (PEG) are reported. Non-aqueous liquid PEG 400 reinforced with high molecular weight PEGs (2 kDa, 6 kDA and 10 kDa) dissolved PDz to form tertiary blends for optimization of viscosity and shear storage modulus. Dynamic photorheometry correlated PEG molar mass and tertiary ratios to adhesion strength, swelling-in-water profile and potential weight loss in aqueous medium. Tertiary blended adhesives demonstrate an improvement in elongation and adhesion strength compared to the binary blends used as control.