Molecular Dispersion Research Articles

A Novel BC2N Monolayer as Anode Material for Li-Ion Battery

The stability, mechanical and electronic properties of a BC2N monolayer and its potential use as an anode material for Li-ion batteries were explored using the density functional theory calculation. The proposed BC2N monolayer shows good thermal and dynamical stabilities, as indicated by the ab initio molecular dynamics simulations and phonon dispersion calculations. The BC2N monolayer exhibits highly anisotropic mechanical properties. The electronic structure calculation based on the hybrid functional suggests that the BC2N monolayer is an indirect bandgap (~1.8 eV) semiconductor. The BC2N monolayer shows linear dichroism and is able to harvest visible and ultraviolet light. To investigate the application of the BC2N monolayer as a potential anode material for Li-ion batteries, the Li adsorption and diffusion on the monolayer were studied. The BC2N monolayer exhibits a high theoretical capacity of 1098 mAh/g for Li-ion batteries. The calculated diffusion barrier of Li ion is 0.45 eV, suggesting a rapid Li-ion charge and discharge rate. The unique mechanical and optical properties of the BC2N monolayer also make it an attractive material for use in advanced nanomechanical and optoelectronic devices.

Contact interaction model of liquid and solid phases

The work implements the approach formulated by B.V. Deryagin, which states for replacing the Coulomb and molecular (dispersion) forces with a system of tensions obtained on the basis of the mechanics of continuum equations using an incompressible liquid model. Interphasal activity modeling is considered from the standpoint of the equilibrium equations of mechanics of continuum using an incompressible liquid model and representing the interfacial tension tensor as a combination of spherical and deviatoric components. Analytical expressions are obtained for the components of the tension tensor depending on the wetting conditions of a solid surface with a liquid. Intermolecular interaction is determined by the value of the internal pressure of the liquid, which is variable over the interfacial layer thickness. The anisotropy of the interfacial tension tensor in the liquid-solid interfacial layer is expressed by the representation of the spherical and deviatoric components combination, which provides the equilibrium conditions for the interfacial layer. The authors propose to consider the adhesive contact as an external force effect of a solid surface on the volume phase of a liquid, leading to the formation of an interfacial tension tensor with components that are variable over the layer thickness. The authors established the nonlinear nature of the interfacial pressure distribution over the layer thickness, due to the difference in interfacial pressures in the liquid and solid phases in the direct contact zone. It is shown that the surface phenomena specificity is due to the deformation of the liquid volume in the interfacial layer, which leads to a change in intermolecular distances in different directions, which occurs with any kind of force acting on the volume phase of the liquid. The law of intermolecular forces distribution of a liquid depending on the distance is established based on the study results of a sitting drop. Expressions are obtained for determining the long-range interaction radius of liquid molecules and the thickness of the liquid-solid interfacial layer, which give a result that fits into the known estimates of the values of these quantities.

The Physical Drivers and Observational Tracers of CO-to-H2 Conversion Factor Variations in Nearby Barred Galaxy Centers

The CO-to-H2 conversion factor (α CO) is central to measuring the amount and properties of molecular gas. It is known to vary with environmental conditions, and previous studies have revealed lower α CO in the centers of some barred galaxies on kiloparsec scales. To unveil the physical drivers of such variations, we obtained Atacama Large Millimeter/submillimeter Array bands (3), (6), and (7) observations toward the inner ∼2 kpc of NGC 3627 and NGC 4321 tracing 12CO, 13CO, and C18O lines on ∼100 pc scales. Our multiline modeling and Bayesian likelihood analysis of these data sets reveal variations of molecular gas density, temperature, optical depth, and velocity dispersion, which are among the key drivers of α CO. The central 300 pc nuclei in both galaxies show strong enhancement of temperature T k ≳ 100 K and density cm−3. Assuming a CO-to-H2 abundance of 3 × 10−4, we derive 4–15 times lower α CO than the Galactic value across our maps, which agrees well with previous kiloparsec-scale measurements. Combining the results with our previous work on NGC 3351, we find a strong correlation of α CO with low-J 12CO optical depths (τ CO), as well as an anticorrelation with T k. The τ CO correlation explains most of the α CO variation in the three galaxy centers, whereas changes in T k influence α CO to second order. Overall, the observed line width and 12CO/13CO 2–1 line ratio correlate with τ CO variation in these centers, and thus they are useful observational indicators for α CO variation. We also test current simulation-based α CO prescriptions and find a systematic overprediction, which likely originates from the mismatch of gas conditions between our data and the simulations.

The Influence of Amphoteric Terpolymerization of Poly (N-Isopropylacrylamide) in the Optimization of the Phase Separation Temperatures

The aim of this study is to fabricate an ampholyte thermo-responsive terpolymers and explore the influence of ampholyte on the phase separation temperatures in different pH solutions. The fabrication of the ampholyte thermo-responsive terpolymers was achieved by terpolymerization of N-isopropylacrylamide (NIPAAm), DIVA (5, 10, and 15 mol.%), and acrylic acid (AA) 10 mol.%. The preparation of the cationic monomer from vanillin was achieved in a facile reaction named 2-((diisopropylamino) methyl)-4-formyl-6-methoxyphenyl acrylate (DIVA). The chemical structures of the monomers and terpolymers were evaluated successfully by 1H, 13C NMR, and FTIR. The average molecular weight and dispersity of the terpolymers were characterized using gel permeation chromatography (GPC); the glass transition temperature, crystallinity, and morphology were characterized using DSC, XRD, and SEM, respectively. The hydrophilic/hydrophobic properties of the fabricated terpolymers, at different pH conditions, were evaluated using contact angle measurements. The lower critical solution temperature (LCST) for all samples was measured using UV–vis spectrophotometer. Moreover, the LCST was tested using different Hofmeister salts in kosmotropic and chaotropic conditions. The findings of this study can be utilized in the bio-separation of biological molecules, as well as drug delivery applications.Graphical

Preparation Strategies of the Anti-Mycobacterial Drug Bedaquiline for Intrapulmonary Routes of Administration.

Mycobacterium tuberculosis (M.tb) has infected one-quarter of the world's population and led to the deaths of 1.6 million individuals in 2021 according to estimates from the World Health Organization. The rise in prevalence of multidrug-resistant and extensively drug-resistant M.tb strains coupled with insufficient therapies to treat such strains has motivated the development of more effective treatments and/or delivery modalities. Bedaquiline, a diarylquinoline antimycobacterial agent, effectively targets mycobacterial ATP synthase but may lead to systemic complications upon oral delivery. Targeted delivery of bedaquiline to the lungs represents an alternative strategy to harness the sterilizing benefits of the drug against M.tb while mitigating off-target side effects. Two pulmonary delivery modalities were developed herein, including dry powder inhalation and liquid instillation. Despite bedaquiline's poor water solubility, spray drying was performed in predominantly aqueous conditions (≥80%) to avoid a closed-loop, inert system. Aerosols of spray-dried bedaquiline with L-leucine excipient outperformed spray-dried bedaquiline alone, demonstrating superior fine particle fraction metrics (~89% of the emitted dose below <5 µm), suitable for inhalation therapies. Furthermore, the use of a 2-hydroxypropyl-β-cyclodextrin excipient allowed a molecular dispersion of bedaquiline in an aqueous solution for liquid instillation. Both delivery modalities were successfully administered to Hartley guinea pigs for pharmacokinetic analysis and were well-tolerated by the animals. Intrapulmonary liquid delivery of bedaquiline led to adequate serum absorption and appropriate peak serum concentrations of the drug. The liquid formulation was superior in systemic uptake compared to the powder formulation. The predominant route via which M.tb bacilli enter the body is aerosol droplets that are deposited onto airway surfaces. For this reason, we believe that further studies should focus on inhalation or intrapulmonary therapies that target the site of entry and primary site of infection for M.tb.

DEVELOPMENT AND CHARACTERIZATION OF PH-RESPONSIVE POLYMERIC MICROBEADS INTERCALATED WITH MONTMORILLONITE FOR CONTROLLED RELEASE OF DOXORUBICIN

Objective: The aim of the present study is to develop pH-responsive polymeric microbeads for controlled release of doxorubicin. Methods: Doxorubicin-encapsulated polymeric microbeads were developed by a simple ionotropic gelation method using sodium alginate, gum ghatti, and montmorillonite (MMT). In this work, we investigate the positive benefits of MMT mineral as a drug carrier for the controlled release of DOX. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) were used to characterize the generated microbeads. The influence of hetero-ionic concentration on drug encapsulation efficiency and drug release from microbeads was examined. In vitro release and swelling studies were performed at pH 2.0 and 7.4 at 37 °C. The cytotoxicity of the developed microbeads was studied using in vitro cultures of the human breast cancer cell line (MCF-7). Results: FTIR confirms the generation of microbeads and also the interaction between the polymer matrix, DOX and MMT clay. XRD analysis reveals the molecular dispersion of DOX and the presence of MMT in the polymeric matrix. SEM studies reveal the developed microbeads are spherical in shape with rough surfaces. Swelling and in vitro release studies are dependent on the pH of the test medium, which may be favorable for intestinal drug delivery. MTT results reveal that the developed microbeads showed good in vitro toxicity against MCF-7 cells. The drug release kinetics of the generated microbeads are followed by both the higuchi and korsmeyer-peppas models. Conclusion: The findings suggest that the DOX-encapsulated microbeads are promising carriers for drug delivery applications. The fabricated microbeads further needs warrant for drug delivery applications.

DEVELOPMENT, CHARACTERIZATION AND ANTIBACTERIAL PROPERTIES OF SILVER NANOPARTICLES LOADED SODIUM ALGINATE/XANTHAN GUM MICROBEADS FOR DRUG DELIVERY APPLICATIONS

Objective: The aim of this study is to create pH-responsive drug carriers, which are useful because they have the potential to improve treatment efficacy by controlling the release rate of ofloxacin from the polymer matrix. Methods: In the first step, silver nanoparticles (Ag NPs) were synthesized from silver nitrate using leaf extract of phyllanthus urinaria L as a reducing agent. In the second step, Ag-NPs-loaded polymeric microbeads were synthesized using sodium alginate (SA) and xanthan gum (XG) for controlled release of ofloxacin (OFLX). The developed microbeads were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), transition electron microscopy (TEM), Selected Area Electron Diffraction (SAED), and scanning electron microscopy (SEM). Swelling and in vitro release studies were performed at pH 2.0 and 7.4 at 37 °C. The in vitro antibacterial activity of microbeads were tested against S. mutans, K. pneumoniae, and B. subtilis. The release kinetics and mechanism were analyzed by fitting the release data into different kinetic models and the korsmeyer-peppas equation. Results: FTIR confirms the generation of silver nanoparticle and also the generation of polymeric microbeads. SEM studies reveal the developed microbeads are spherical in shape with rough surfaces. TEM studies reveal the size of 20-40 nm. XRD analysis reveals the molecular dispersion of DOX and the presence of silver nanoparticles in the polymeric matrix. Investigations of in vitro release and swelling studies show that the developed microbeads are relatively suitable for intestinal drug delivery because higher release rate was observed at pH 7.4. The developed microbead follows non-Fickian diffusion drug release mechanism. The created samples exhibited antimicrobial activity against S. mutans, K. pneumoniae, and B. subtilis. Conclusion: The results indicate that microbeads containing OFLX and silver nanoparticles are effective drug-delivery vehicles. A further warrant is required for the use of manufactured microbeads in drug delivery applications.

Sub-micro Organosolv lignin as bio-based epoxy polymer component: A sustainable curing agent and additive.

Sub-micro organosolv lignin (OBs) isolated from beechwood biomass, comprising of sub-micro sized particles (570 nm), with low molecular weight (Mw) and dispersity (Ð), and relatively high total phenolic -OH content, was successfully utilized for the production of bio-based epoxy polymer composites. OBs lignin was incorporated in the glassy epoxy system based on diglycidyl ether of bisphenol A (DGEBA) and aliphatic polyoxypropylene α,ω-diamine (Jeffamine D-230), being utilized both as curing agent replacing partially D-230 as well as an additive, substituting part of both petroleum derived components. Up to 12 wt.% replacement of D-230 by OBs lignin was achieved, while a total of ~17 wt.% of OBs effectively replaced the conventional epoxy polymer. The incorporation of OBs lignin in the polymeric matrix was achieved without the use of any solvent or previous functionalization. Enhanced properties were obtained, with substantial increase of tensile strength, strain, and stiffness, Tg, antioxidant activity and resistance to solvents.

The Effect of Aging on the Molecular Distribution of Crumb Rubber Modified Asphalt Based on the Gel Permeation Chromatography Test

Asphalt aging is one of the main causes of asphalt pavement cracking, loosening and other issues. On a macro level, the asphalt hardens and becomes more brittle, while on a micro level, the chemical composition and molecular weight distribution change. This is a very complicated physicochemical process. Gel permeation chromatography (GPC) is a powerful technical tool for understanding the mechanism of asphalt aging and expressing the asphalt aging process. GPC can be used to measure the distribution and content of each component in the asphalt aging process. The mechanism of action of crumb rubber modified asphalt has not been fully elucidated due to its complex composition. This study investigated the molecular weight of crumb rubber modified asphalt before and after aging, and filtered asphalt based on gel permeation chromatography. The results indicated that crumb rubber itself experiences severe degradation following PAV aging and that a significant number of macromolecular materials are incorporated into the asphalt phase, causing changes in key parameters. The average molecular weight (Mw) and dispersion (D) of crumb rubber modified asphalt are directly related. At the same time, the Mw of crumb rubber modified asphalt has a positive correlation with LMS content, while SMS content has a negative correlation with Mw. The increase in crumb rubber content has a positive impact on the material interaction, and the molecular weight distribution of crumb rubber modified asphalt is affected by the reaction degree of the crumb rubber in asphalt. The complex physical and chemical reaction of crumb rubber in asphalt has a direct impact on the external macro rheological properties of asphalt.

Properties and molecular self‐assembly of liquid crystalline hard–hard diblock and hard–soft–hard triblock copolymers influenced by Flory–Huggins interaction parameter and volume fraction of distinct segments

AbstractTwo series of hybrid liquid crystalline (LC) diblock copolymers (DBCs) and triblock copolymers (TBCs) composed of hard and soft blocks with great control over their molecular masses, dispersities (Mw/Mn = Đ ≤ 1.38) and compositions were prepared via reversible addition‐fragmentation chain transfer polymerization in anisole solvent using new p‐dodecylphenyl‐N‐acrylamide monomer, azobisisobutyronitrile initiator, poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate) and poly(2‐[2‐(4‐cyano‐azobenzene‐4‐oxy)ethylene‐oxy]ethyl methacrylate)‐block‐poly(n‐butyl methacrylate) macroinitiators. Structures and properties of BCs were characterized by proton nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimeter, optical polarizing microscope, atomic force microscope and grazing‐incidence small angle X‐ray scattering. Kinetic behavior indicated that block copolymerization proceeded with controlled/living characteristics. Every BCs revealed three endothermic transitions corresponding to glassy phase transition, smectic‐to‐nematic phase transition (TS‐N) and melting phase transition. DBC‐1, DBC‐2, TBC‐1 and TBC‐2 with high‐LC volume fractions exhibited strong TS‐N contrasted to DBC‐3, DBC‐4, TBC‐3 and TBC‐4 having low‐LC contents. DBC‐1, DBC‐2, DBC‐3, TBC‐1 and TBC‐2 evidenced smectic C structure while TBC‐3 containing low‐LC segment (39 wt%) showed nematic structure. Morphologies of block copolymer thin films in mixed solvent (Tetrahydrofuran/cyclohexane) vapor annealing system varied significantly, depending on the volume fractions of building blocks and the interactions between the blocks and solvents.

Superior hydrogen storage capacity of Vanadium decorated biphenylene (Bi+V): A DFT study

Herein, the hydrogen storage competency of vanadium-decorated biphenylene (Bi+V) has been investigated using Density Functional Theory simulations. The metal atom interacts with biphenylene with a binding energy value of −2.49 eV because of charge transfer between V 3d and C 2p orbitals. The structure and electronic properties are studied in terms of adsorption energy values, the spin-polarized partial density of states (PDOS), band structure plots, and charge transfer analysis. The Kubas-type interactions lead to average hydrogen adsorption energy values of −0.51 eV/H2 which fulfills DOE-US criteria (0.2–0.7 eV/H2). The diffusion energy barrier value of 1.75 eV lowers the chances of metal clustering. The complex binds 5H2 on each V-atom resulting in a storage capacity of 7.52 wt% with an average desorption temperature of 595.96 K. The ab-initio molecular dynamics (AIMD) and phonon dispersions validates structural integrity at higher temperatures suggesting the excellent storage properties of this material at room temperature.

Molecular Dispersion Spectroscopy Using a Code-Division-Multiplexed Optical Carrier

A fiber-optic molecular dispersion spectrometer using code-division multiplexing to make simultaneous phase measurements of a hydrogen cyanide (${\mathrm{H}}^{13}{\mathrm{C}}^{14}\mathrm{N}$) $2{\ensuremath{\nu}}_{3}$-band P10 rovibrational transition at multiple optical frequencies is demonstrated. A second-derivative anomalous dispersion response is digitally synthesized from sets of these concurrent measurements. The synthesized measurement demonstrates 3 orders of magnitude noise suppression relative to individual measurements, has intrinsic wavelength tuning linearization, and a spectroscopic detection limit of $146\phantom{\rule{0.2em}{0ex}}\mathrm{ppb}\phantom{\rule{0.1em}{0ex}}\mathrm{m}/\sqrt{\mathrm{Hz}}$.

Fabrication of nanoparticulate system for oral delivery of Naringenin against paraquat-induced Parkinson's disorder in Wistar rats

BackgroundParkinson's disorder (PD) is a neurodegenerative condition associated with slow movement, tremors, imbalance, bradykinesia, and rigidity with advanced complications like sleep disorder, pains, sensory disability, and cognitive impairment. As per World Health Organization, PD is the leading neurological disorder worldwide. Although Parkinson's disorder cannot be cured, medications might significantly improve the symptoms. Current treatment for Parkinson's disorder includes cell implantation, Gene therapy, Surgical approaches, and Rehabilitation. But there are several adverse effects associated with these treatment methods which can be addressed using nanoparticles that possesses the ability to cross the blood-brain barrier, increased stability against enzymatic degradation, lowers liver toxicity, etc. Several Phyto-constituent have proven their role in the management of Parkinson's disorder. One such natural flavonoid is Naringenin, which is been reported to have diverse neuronal effects. Materials and methodsIn the first part, the Naringenin-loaded PLGA nanoparticles were fabricated by using a single emulsion solvent emulsion method. Optimization was performed by using a 32-factorial design to investigate the impact of independent variables viz. PLGA concentration and number of HPH cycles. The optimized batch was spray-dried and evaluated for DSC, XRD, and SEM to confirm desired characteristics. LD50 was determine by performing Acute Oral Toxicity (AOT) study as per OECD-420 guidelines. Parkinson was induced by injecting rats with paraquat (i.p.) twice a week for 6 weeks. Simultaneously, nano-suspension and standard drug were also administered orally to respective group 60min prior to paraquat every day for 6 weeks. After 42/45 days parameters like Gross examination of the brain, Relative brain weight determination, behavioral parameters, biochemical evaluation (MDA, SOD, CAT, GSH, α-synuclein protein levels), and immunohistochemistry (BDNF level) investigation were performed. Brain histopathological study was performed to support the findings. ResultsAn optimized batch of Naringenin-loaded PLGA nanoparticles showed particle size, PDI, and %EE as 162.1 ​nm, 0.288, and 91% respectively. Spray-dried nanoparticles were found to be spherical during SEM analysis which may facilitate the easy movement of nanoparticles through different barriers. The DSC and XRD study confirmed the molecular dispersion of the drug. In vivo studies showed quite promising results through behavioural, histopathological, biochemical, and immunohistochemistry evaluations. ConclusionsIn conclusion, Naringenin-loaded PLGA nanoparticles showed a protective effect on the levels of MDA, SOD, CAT, GSH, α- Synuclein protein, and BDNF and prevented the neurodegeneration in brain tissue in Paraquat-induced Parkinson's disorder. Based on the outcomes of present study, the use of Naringenin-loaded PLGA nanoparticle dispersion is the promising alternative available to Parkinson's disorder treatment.

Studying spatial drug distribution in golf ball-shaped microspheres to understand drug release

Poly (lactic-co-glycolic acid) (PLGA) microspheres have been one of the most successful products for slow drug release. While distribution of drugs in microspheres might be a fundamental factor affecting drug release, it has been often overlooked. Indeed, very few studies are available on the distribution of drugs in microspheres with complex morphology like golf ball-shaped microspheres. In this paper, the distribution of rotigotine in golf ball-shaped microspheres (GSRM) was investigated by argon ion milling, combined with scanning electron microscopy and energy dispersive X-ray spectroscopy (AIM-SEM-EDS). Rotigotine in GSRM was clearly observed in two forms, respectively in an aggregated state and as a molecular dispersion. The distribution of palmitic acid in the microspheres (used as an additive to reduce burst release) was also demonstrated: 10% was found on the microspheres' surface while 90% separated from the polymer to form small particles inside the microspheres onto which rotigotine aggregated through hydrogen bonding interactions. In in-vitro release studies we observed that first the phase-separated palmitic acid/rotigotine particles dissolved and released the drug, followed by the release of the molecularly dispersed rotigotines by osmosis. We also found that rotigotine accelerated the degradation and reduced the glass transition temperature of PLGA, which played an important role as well in the release of the drug from GSRM. Finally, two linear Level A in vitro-in vivo correlations were established and validated, indicating that the in vitro release testing could be a meaningful predictor for the in vivo performance of GSRM. Our work demonstrates the importance of studying drug distribution in complex microspheres to understand drug release.

Degradation-Influenced/Induced Self-Assembly of Copolymers with the Combinatory Effects of Changed Molecular Weight and Dispersity

Degradation-Influenced/Induced Self-Assembly of Copolymers with the Combinatory Effects of Changed Molecular Weight and Dispersity

Sequence-Enhanced Self-Healing in "Lock-and-Key" Copolymers.

Van der Waals-driven self-healing in copolymers with "lock-and-key" architecture has emerged as a concept to endow engineering-type polymers with the capacity to recover from structural damage. Complicating the realization of "lock-and-key"-enabled self-healing is the tendency of copolymers to form nonuniform sequence distributions during polymerization reactions. This limits favorable site interactions and renders the evaluation of van der Waals-driven healing difficult. Here, methods for the synthesis of lock-and-key copolymers with prescribed sequence were used to overcome this limitation and enable the deliberate synthesis of "lock-and-key" architectures most conducive to self-healing. The effect of molecular sequence on the material's recovery behavior was evaluated for the particular case of three poly(n-butyl acrylate/methyl methacrylate) [P(BA/MMA)] copolymers with similar molecular weights, dispersity, and overall composition but with different sequences: alternating (alt), statistical (stat), and gradient (grad). They were synthesized using atom transfer radical polymerization (ATRP). Copolymers with alt and stat sequence displayed a 10-fold increase of recovery rate compared to the grad copolymer variant despite a similar overall glass transition temperature. Investigation with small-angle neutron scattering (SANS) revealed that rapid property recovery is contingent on a uniform microstructure of copolymers in the solid state, thus avoiding the pinning of chains in glassy MMA-rich cluster regions. The results delineate strategies for the deliberate design and synthesis of engineering polymers that combine structural and thermal stability with the ability to recover from structural damage.

Molecular data, ecological niche, and dispersal models reveal a trans-Atlantic shallow-water octopus species

The tropical Octopus insularis is a shallow-water species widely distributed in the western Atlantic. Recent studies of niche models have identified suitable habitats for its settlement also on the east coast of the Atlantic. Considering the pelagic larval period and the high tolerance of this species to environmental variations, this study aimed to analyze the possibility of O. insularis occurrence in the West Atlantic (São Tomé Island) through molecular analyses, dispersion, and niche models. The molecular analyses were performed using fragments of 481 bp of the mitochondrial gene (cox1) from three muscle samples collected in São Tomé Island. The O. insularis long-range connectivity between South America and Western Africa was analyzed using a Lagrangian particle tracking model. Additionally, O. insularis records across its entire known distribution were applied to run the ecological niche model (ENM) using the Maxent algorithm. The Bayesian phylogenetic reconstruction showed that two of the three octopus sequences from São Tomé island (Central-Western Africa) belong to a monophyletic and well-supported O. insularis clade. The third octopus sample revealed a new species related to the clade with the Octopus vulgaris species complex. The dispersal models pointed out that passive particles could potentially reach the seamounts region at Africa coast via oceanic currents (mainly the North Equatorial Countercurrent) from São Pedro and São Paulo archipelago (Central-Western Region of the Atlantic) in a period of ∼30–60 days. This suggests that São Pedro and São Paulo archipelago could act as a potential source of paralarvae to Western Africa, although we hypothesize that this connection was more common during the Pleistocene, when sea level was around 120 m lower. In addition to the already known areas of O. insularis occurrence, the ENM pointed suitable habitats to the octopus settlement from Guinea-Bissau down to Equatorial Guinea and Gabon, and African Islands, such as São Tomé and Príncipe. The new record of O. insularis in Africa raises important questions regarding regional fisheries management. Considering that O. insularis is highly tolerant to environmental variations and very adapted to warm shallow waters, there is a possibility that octopus fisheries stocks on the African coast have a mixed composition (O. vulgaris, O. insularis, and Octopus sp.) and therefore the fisheries must follow management measures suitable for each species. In addition, further studies should be carried out in order to characterize and describe the potential new octopus species found only in São Tomé Island according to our genetic survey.

Enhancement of itraconazole solubility and release by hot-melt extrusion with Soluplus®

Formulation of poorly water-soluble drugs is a significant challenge in the development of oral solid dosage forms. The objective was to investigate the effect of hot-melt extrusion process and formulation variables on the solid state, solubility and release of an ionizable poorly soluble drug, itraconazole (ITZ). Amorphous solid dispersions (ASD) were prepared by hot-melt extrusion and characterized by differential scanning calorimetry, x-ray diffractometry, FTIR spectroscopy and drug release. ITZ with the amphiphilic polymer carrier, Soluplus® resulted in molecular dispersions and improved drug solubility. The release of ITZ increased with increasing Soluplus® amount. Supersaturation was maintained for >24 h due to molecular dispersion of the drug in the carrier and the subsequent solubilization effect of the carrier. A lower supersaturation was obtained at processing temperatures (130 °C) below the drug melting point. The drug release was relatively slow, but complete within 6-8 h from large 5 mm extrudates and increased significantly by milling the extrudates and was nearly independent of particle size below 425 μm. In conclusion, the ASD led to solubility and release enhancement of the poorly water-soluble drug ITZ.

Strengthening and toughening of polybenzoxazine by incorporation of polyrotaxane molecules

A mechanically interlocked supramolecule polyrotaxane (PR) was utilized as a functional additive to modify the hydrogen bonding (H-bonding) and cross-linking network of polybenzoxazine (PBa). Epoxide and hydroxyl groups at the terminal end of polycaprolactone grafted on CDs were chosen to investigate how these functional groups influence H-bonding, morphology, and mechanical properties of PBa matrix. Fourier transform infrared spectroscopy and differential scanning calorimetry results show evidence of successful manipulation of H-bonding and curing kinetics of PBa in the presence of the functionalized PR. After curing, epoxide functionalized PR (EPR) shows a strong interaction with PBa, leading to molecular level dispersion in PBa compared to PR with the hydroxyl functional group. By introducing only 4 wt% of EPR in PBa, the ductility and fracture toughness of PBa are greatly improved without a noticeable drop in Young's Modulus, which is attractive for aerospace and microelectronic applications.

Gelation in Photoinduced ATRP with Tuned Dispersity of the Primary Chains.

We investigated gelation in photoinduced atom transfer radical polymerization (ATRP) as a function of Cu catalyst loading and thus primary chain dispersity. Using parallel polymerizations of methyl acrylate with and without the addition of a divinyl crosslinker (1,6-hexanediol diacrylate), the approximate values of molecular weights and dispersities of the primary chains at incipient gelation were obtained. In accordance with the Flory-Stockmayer theory, experimental gelation occurred at gradually lower conversions when the dispersity of the primary chains increased while maintaining a constant monomer/initiator/crosslinker ratio. Theoretical gel points were then calculated using the measured experimental values of dispersity and initiation efficiency. An empirical modification to the Flory-Stockmayer equation for ATRP was implemented, resulting in more accurate predictions of the gel point. Increasing the dispersity of the primary chains was found not to affect the distance between the theoretical and experimental gel points and hence the extent of intramolecular cyclization. Furthermore, the mechanical properties of the networks, such as equilibrium swelling ratio and shear storage modulus showed little variation with catalyst loading and depended primarily on the crosslinking density.