Simultaneous continuous,nonchromatographic monitoring and discrete chromatographic monitoring of polymerization reactions

Automatic continuous nonchromatographic monitoring and discrete chromatographic monitoring were coupled together for the first time and used to monitor free radical and controlled‐radical polymerization reactions. This was achieved by adding a multidetector Size Exclusion Chromatography (SEC) system (alternatively termed Gel Permeation Chromatography, GPC) to the ACOMP platform (Automatic Continuous Online Monitoring of Polymerization reactions). The fact that the reactor solution is already preconditioned in the ACOMP front‐end to the concentration levels used in SEC makes direct coupling possible. Kinetics from two different types of reactions, Reversible Addition Fragmentation Transfer (RAFT) and free radical polymerization of butyl acrylate were studied, including the production of a bimodal population. Complementary and contrasting features from the continuous and SEC approaches are highlighted. The main advantage of the SEC detection is to follow the evolution of full molecular weight distributions (MWD), especially in ‘living’ type reactions, where polydispersity decreases with monomer conversion, whereas the continuous detection provides a much more detailed characterization of the reaction. Interestingly, in the case where a bimodal molecular weight distribution was produced, the continuous method automatically detected the onset of the second mode in a model independent fashion, whereas SEC could only discern the bimodality by applying preconceived models. The SEC approach will have valuable niche applications, however, such as when reactions are relatively slow, monitoring narrow polydispersity is of primary importance, and also in copolymerization and terpolymerization reactions where complex mixtures of reagents (e.g., RAFT agents, copper ions, etc.) make unfractionated spectroscopic resolution of comonomers difficult. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Stem Cell Therapy Enhances Motor Activity of Triceps Surae Muscle in Mice with Hereditary Peripheral Neuropathy

Impaired motor and sensory functions are the main features of Charcot–Marie–Tooth disease. Mesenchymal stem cell (MSCs) therapy is one of the possible treatments for this disease. It was assumed that MSCs therapy can improve the contractile properties of the triceps surae (TS) muscles in mice with hereditary peripheral neuropathy. Murine adipose-derived mesenchymal stromal cells (AD-MSCs) were obtained for transplantation into TS muscles of FVB-C-Tg(GFPU)5Nagy/J mice. Three months after AD-MSCs transplantation, animals were subjected to electrophysiological investigations. Parameters of TS muscle tension after intermittent high frequency electrical sciatic nerve stimulations were analyzed. It was found that force of TS muscle tension contraction in animals after AD-MSCs treatment was two-time higher than in untreated mice. Normalized values of force muscle contraction in different phases of electrical stimulation were 0.3 ± 0.01 vs. 0.18 ± 0.01 and 0.26 ± 0.03 vs. 0.13 ± 0.03 for treated and untreated animals, respectively. It is assumed that the two-fold increase in TS muscle strength was caused by stem cell therapy. Apparently, AD-MSCs therapy can promote nerve regeneration and partial restoration of muscle function, and thus can be a potential therapeutic agent for the treatment of peripheral neuropathies.     

Molecular electronic devices based on single-walled carbon nanotube electrodes

As the top-down fabrication techniques for silicon-based electronic materials have reached the scale of molecular lengths, researchers have been investigating nanostructured materials to build electronics from individual molecules. Researchers have directed extensive experimental and theoretical efforts toward building functional optoelectronic devices using individual organic molecules and fabricating metal-molecule junctions. Although this method has many advantages, its limitations lead to large disagreement between experimental and theoretical results. This Account describes a new method to create molecular electronic devices, covalently bridging a gap in a single-walled carbon nanotube (SWNT) with an electrically functional molecule. First, we introduce a molecular-scale gap into a nanotube by precise oxidative cutting through a lithographic mask. Now functionalized with carboxylic acids, the ends of the cleaved carbon nanotubes are reconnected with conjugated diamines to give robust diamides. The molecular electronic devices prepared in this fashion can withstand and respond to large environmental changes based on the functional groups in the molecules. For example, with oligoanilines as the molecular bridge, the conductance of the device is sensitive to pH. Similarly, using diarylethylenes as the bridge provides devices that can reversibly switch between conjugated and nonconjugated states. The molecular bridge can perform the dual task of carrying electrical current and sensing/recognition through biological events such as protein/substrate binding and DNA hybridization. The devices based on DNA can measure the difference in electrical properties of complementary and mismatched strands. A well-matched duplex DNA 15-mer in the gap exhibits a 300-fold lower resistance than a duplex with a GT or CA mismatch. This system provides an ultrasensitive way to detect single-nucleotide polymorphisms at the individual molecule level. Restriction enzymes can cleave certain cDNA strands assembled between the SWNT electrodes; therefore, these strands maintain their native conformation when bridging the ends of the SWNTs. This methodology for creating novel molecular circuits forges both literal and figurative connections between chemistry, physics, materials science, and biology and promises a new generation of integrated multifunctional sensors and devices.     

Characterization of artisanally and semiautomatically extracted argan oils from Morocco

The present study was conducted to know the possible influence of the seed treatment, method of extraction and geographical origin on the quality and chemical composition of argan oil. Artisanally and semiautomatically extracted argan oils, from roasted and unroasted seeds, from interior and coast areas, were studied. The quality parameters analyzed were acid value, peroxide value, K₂₃₂ and K₂₇₀, triacylglycerols and fatty acid composition, polar compounds, total phenols, tocopherol content and oil stability index (OSI). Seed treatment and extraction method showed a higher influence on quality parameters than geographical area; the quality parameters of the different oils were discussed. The total phenolic content in all analyzed samples was lower than 10 ppm. γ‐Tocopherol was the major tocopherol (84.4–86.4%) with a high contribution to the total tocopherol content (383–485 ppm). The OSI of the argan oil samples were well correlated (R = 0.97) with the tocopherol contents. The argan oil samples obtained from roasted seeds presented higher stability (26–38 h) than the oils from unroasted seeds (16–32 h).     

GPR55 Receptor Activation by the N-Acyl Dopamine Family Lipids Induces Apoptosis in Cancer Cells via the Nitric Oxide Synthase (nNOS) Over-Stimulation

GPR55 is a GPCR of the non-CB1/CB2 cannabinoid receptor family, which is activated by lysophosphatidylinositol (LPI) and stimulates the proliferation of cancer cells. Anandamide, a bioactive lipid endocannabinoid, acts as a biased agonist of GPR55 and induces cancer cell death, but is unstable and psychoactive. We hypothesized that other endocannabinoids and structurally similar compounds, which are more hydrolytically stable, could also induce cancer cell death via GPR55 activation. We chemically synthesized and tested a set of fatty acid amides and esters for cell death induction via GPR55 activation. The most active compounds appeared to be N-acyl dopamines, especially N-docosahexaenoyl dopamine (DHA-DA). Using a panel of cancer cell lines and a set of receptor and intracellular signal transduction machinery inhibitors together with cell viability, Ca²⁺, NO, ROS (reactive oxygen species) and gene expression measurement, we showed for the first time that for these compounds, the mechanism of cell death induction differed from that published for anandamide and included neuronal nitric oxide synthase (nNOS) overstimulation with concomitant oxidative stress induction. The combination of DHA-DA with LPI, which normally stimulates cancer proliferation and is increased in cancer setting, had an increased cytotoxicity for the cancer cells indicating a therapeutic potential.     

Natural Antioxidants in Anemia Treatment

Anemia, characterized by a decrease of the hemoglobin level in the blood and a reduction in carrying capacity of oxygen, is a major public health problem which affects people of all ages. The methods used to treat anemia are blood transfusion and oral administration of iron-based supplements, but these treatments are associated with a number of side effects, such as nausea, vomiting, constipation, and stomach pain, which limit its long-term use. In addition, oral iron supplements are poorly absorbed in the intestinal tract, due to overexpression of hepcidin, a peptide hormone that plays a central role in iron homeostasis. In this review, we conducted an analysis of the literature on biologically active compounds and plant extracts used in the treatment of various types of anemia. The purpose of this review is to provide up-to-date information on the use of these compounds and plant extracts, in order to explore their therapeutic potential. The advantage of using them is that they are available from natural resources and can be used as main, alternative, or adjuvant therapies in many diseases, such as various types of anemia.     

Flavonoids in Skin Senescence Prevention and Treatment

Skin aging is associated with the accumulation of senescent cells and is related to many pathological changes, including decreased protection against pathogens, increased susceptibility to irritation, delayed wound healing, and increased cancer susceptibility. Senescent cells secrete a specific set of pro-inflammatory mediators, referred to as a senescence-associated secretory phenotype (SASP), which can cause profound changes in tissue structure and function. Thus, drugs that selectively eliminate senescent cells (senolytics) or neutralize SASP (senostatics) represent an attractive therapeutic strategy for age-associated skin deterioration. There is growing evidence that plant-derived compounds (flavonoids) can slow down or even prevent aging-associated deterioration of skin appearance and function by targeting cellular pathways crucial for regulating cellular senescence and SASP. This review summarizes the senostatic and senolytic potential of flavonoids in the context of preventing skin aging.     

Computing Optimal Diameter-Bounded Polygon Partitions

The minimum -small partition problem is the problem of partitioning a given simple polygon into subpolygons, each with diameter at most , for a given > 0. This paper considers the version of this problem that disallows Steiner points. This problem is motivated by applications in mesh generation and collision detection. The main result in the paper is a polynomial-time algorithm that solves this problem, and either returns an optimal partition or reports the nonexistence of such a partition. This result contrasts with the recent NP-completeness result for the minimum -small partition problem for polygons with holes (C. Worman, 15th Canadian Conference on Computational Geometry, 2003). Even though the running time of our algorithm is a polynomial in the input size, it is prohibitive for most real applications and we seek faster algorithms that approximate an optimal solution. We first present a faster 2-approximation algorithm for the problem for simple polygons and then a near linear-time algorithm for convex polygons that produces, for any > 0, an (+)-small partition with no more polygons than in an optimal -small partition. We also present an exact polynomial-time algorithm for the minimum -small partition problem with the additional constraint that each piece in the partition be convex.     

An Operator Approach to Tangent Vector Field Processing

In this paper, we introduce a novel coordinate‐free method for manipulating and analyzing vector fields on discrete surfaces. Unlike the commonly used representations of a vector field as an assignment of vectors to the faces of the mesh, or as real values on edges, we argue that vector fields can also be naturally viewed as operators whose domain and range are functions defined on the mesh. Although this point of view is common in differential geometry it has so far not been adopted in geometry processing applications. We recall the theoretical properties of vector fields represented as operators, and show that composition of vector fields with other functional operators is natural in this setup. This leads to the characterization of vector field properties through commutativity with other operators such as the Laplace‐Beltrami and symmetry operators, as well as to a straight‐forward definition of differential properties such as the Lie derivative. Finally, we demonstrate a range of applications, such as Killing vector field design, symmetric vector field estimation and joint design on multiple surfaces.