Synthesis and preparation of biodegradable and visible light crosslinkable unsaturated fumarate‐based networks for biomedical applications

Biodegradable polymers have currently attracted high interest as ideal carriers in drug delivery and tissue engineering applications. In situ forming devices based on these materials will synergistically provide the advantages of the customary prefabricated devices as well as ease of administration. To acheive these objectives, optically transparent and biodegradable macromers based on poly(ethylene glycol) and fumaric acid copolymers were synthesized using propylene oxide as a different proton scavenger to enhance in situ photocrosslinking capability. The macromers in different compositions were then photocured for 300 sec in the presence of a visible light initiator/accelerator couple and also a reactive diluent. Characterization of the macromers and the resulting networks were performed using different spectroscopic, chromatographic, physical, and thermal analysis techniques. The resulted shrinkage strain of the macromers upon photocuring was studied using the bounded disk technique, and initial shrinkage strain rates were obtained by numerical differentiation. Our results suggest that the compositions based on these unsaturated aliphatic polyesters are potentially useful to develop injectable, in situ photocrosslinkable carriers for drug and cell delivery applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Gas-phase observation of the heterolytic dissociation of negative ions into counter ions: Dissociation of [Cu phthalocyanine (SO<Subscript>3</Subscript>)<Subscript>4</Subscript>Na]<Superscript>3−</Superscript>.

Ion pair formation proceeding in solution at room-temperature, where it is driven by energies of solvation, has been observed in the gas-phase in the collision-induced dissociation of [Cu phthalocyanine (SO3)4Na]3- and [Cu phthalocyanine (SO3)4Na2]2- at low energies. The gas-phase observation of these charge separations into positive and negative ions, seemingly counter-intuitive, is favored sufficiently by thermodynamics to proceed at low collision energies. The combination of a high stability of the negative product anion against electron detachment and a low recombination energy of the departing positive counter ion appears to be the key requirement for such dissociations to proceed at low energies in the gas-phase.     

Effect of shear strain on the α-ε phase transition of iron: a new approach in the rotational diamond anvil cell

The effect of shear strain on the iron α-ε phase transformation has been studied using a rotational diamond anvil cell (RDAC). The initial transition is observed to take place at the reduced pressure of 10.8?GPa under pressure and shear operation. Complete phase transformation was observed at 15.4?GPa. The rotation of an anvil causes limited pressure elevation and makes the pressure distribution symmetric in the sample chamber before the phase transition. However, it causes a significant pressure increase at the centre of the sample and brings about a large pressure gradient during the phase transformation. The resistance to the phase interface motion is enhanced due to strain hardening during the pressure and shear operations on iron and this further increases the transition pressure. The work of macroscopic shear stress and the work of the pressure and shear stress at the defect tips account for the pressure reduction of the iron phase transition.     

Dispersive liquid-liquid microextraction and liquid chromatographic determination of pentachlorophenol in water

A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol (PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent. The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear dynamic range (0.1–1000 μg L⁻¹) and low detection limit (0.03 μg L⁻¹), which makes it suitable for determination of PCP in water samples.      

Periodic solution for strongly nonlinear vibration systems by He's variational iteration method

In this paper, we use variational iteration method for strongly nonlinear oscillators. This method is a combination of the traditional variational iteration and variational method. Some examples are given to illustrate the effectiveness and convenience of the method. The obtained results are valid for the whole solution domain with high accuracy. The method can be easily extended to other nonlinear oscillations and hence widely applicable in engineering and science. Copyright © 2009 John Wiley & Sons, Ltd.     

The Genus Haplophyllum Juss.: Phytochemistry and Bioactivities—A Review

Herein, a comprehensive review is given focusing on the chemical profiles of the essential oils (EOs), non-volatile compounds, ethnobotany, and biological activities of different Haplophyllum (Rutaceae family) species. To gather the relevant data, all the scientific databases, including Scopus, ISI-WOS (Institute of Scientific Information-Web of Science), and PubMed and highly esteemed publishers such as Elsevier, Springer, Taylor and Francis, etc., were systematically retrieved and reviewed. A wide array of valuable groups of natural compounds, e.g., terpenoids, coumarins, alkaloids, lignans, flavonoids, and organic acids have been isolated and subsequently characterized in different organic extracts of a number of Haplophyllum species. In addition, some remarkable antimicrobial, antifungal, anti-inflammatory, anticancer, cytotoxic, antileishmanial, and antialgal effects as well as promising remedial therapeutic properties have been well-documented for some species of the genus Haplophyllum.     

From the generalized uncertainty relations on fuzzy <Emphasis Type="Italic">AdS</Emphasis><Subscript>2</Subscript> to the Poincaré geometry

The positive and discrete unitary irreps of SU(1,1) are used to construct fuzzy (Euclidean) AdS ₂. Two different types of uncertainty relation involving the Weyl–Heisenberg and a weaker type are studied. It is shown that there are no generalized coherent states which simultaneously minimize the Weyl–Heisenberg uncertainty relations among three non-commuting embedding coordinates of the fuzzy AdS ₂. However, generalized squeezed states that simultaneously satisfy the three weaker uncertainty relations do exist, and reproduce some properties of the classical AdS ₂. Up to a common scaling factor in terms of the irrep label, the expectation values of the non-commuting coordinates over such states are described in the same manner as the classical AdS ₂, in terms of the Poincaré coordinates. The expectation values on the fuzzy AdS ₂ tend to their corresponding values in the commutative limit.     

Vibration analysis of piezoelectric nanowires with surface and small scale effects

An analytical model for predicting surface effects on the free transverse vibrations of piezoelectric nanowires (NWs) is developed based on the non-local Euler-Bernoulli beam theory. The governing equation of motion for the piezoelectric NW with consideration of both surface and non-local effects is initially obtained, and the exact expressions for the natural frequencies and the fundamental buckling voltage are derived for simple support conditions. In addition, an explicit relationship between the residual surface tension and the small scale parameter of the piezoelectric NW, in terms of the critical electric potential at which the axial buckling occurs, is offered. Accordingly, a design chart is presented which may assist in experimental characterization of the mechanical properties of piezoelectric NW-based devices.     

Sodium Phytate-Incorporated Gelatin-Silicate Nanoplatelet Composites for Enhanced Cohesion and Hemostatic Function of Shear-Thinning Biomaterials

Shear-thinning biomaterials (STBs) based on gelatin-silicate nanoplatelets (SNs) are emerging as an alternative to conventional coiling and clipping techniques in the treatment of vascular anomalies. Improvements in the cohesion of STB hydrogels pave the way toward their translational application in minimally invasive therapies such as endovascular embolization repair. In the present study, sodium phytate (Phyt) additives are used to tune the electrostatic network of SNs-gelatin STBs, thereby promoting their mechanical integrity and facilitating injectability through standard catheters. We show that an optimized amount of Phyt enhances storage modulus by approximately one order of magnitude and reduces injection force by ≈58% without compromising biocompatibility and hydrogel wet stability. The Phyt additives are found to decrease the immune responses induced by SNs. In vitro embolization experiments suggest a significantly lower rate of failure in Phyt-incorporated STBs than in control groups. Furthermore, the addition of Phyt leads to accelerated blood coagulation (reduces clotting time by ≈45% compared to controls) due to the contributions of negatively charged phosphate groups, which aid in the prolonged durability of STB in coagulopathic patients. Therefore, the proposed approach is an effective method for the design of robust and injectable STBs for minimally invasive treatment of vascular malformations.