196,205 research outputs found
Synthesis and structural characterisation of CuII-based MOFs constructed by combining functionalised 1,4-bis(1H-imidazol-1-Yl)benzene ligands with copper sulfate
No full textAnion-pillared metal-organic frameworks (APMOFs) are a class of coordination polymers in which divalent anions connect two adjacent layers of a 2D network generated by neutral ligands and cationic metal centres. This class of MOFs is commonly composed by materials built using pyridine-based ligands and octahedral fluorinated anions as linear pillars. Only recently, the use of nitrogen based five-membered ring ligands and/or tetrahedral anions, such as sulfate, has been reported. The combination of 1,1′-(2-(trifluoromethyl)-1,4-phenylene)bis(1H-imidazole) (bibCF3) ligand with copper(ii) sulfate generates a 2D MOF (UdP-20) of minimal formula [CuSO4(bibCF3)1.5]·3H2O. UdP-20 possesses a square lattice (sql) topology in which the copper sulfate dimer molecular building block acts as 4-connected nodes and exhibits flexibility, transitioning to a closed pore phase (UdP-20-cp) upon heating. The use of different functionalised bib ligands allowed us to obtain three new examples of APMOFs: UdP-21 with 1,1′-(2-chloro-1,4-phenylene)bis(1H-imidazole) (bibCl), UdP-22 with 1,1′-(2-methyl-1,4-phenylene)bis(1H-imidazole) (bibMe) and UdP-23 with 1,1′-(2-methoxy-1,4-phenylene)bis(1H-imidazole) bibOMe. All these materials possess 2D layers connected to each other by bridging sulfate anions leading to an overall 3D anion pillared framework. All the herein reported materials were characterised by elemental analysis, thermogravimetric analysis, and powder and single crystal X-ray diffraction. Moreover, their CO2 adsorption behaviour was investigated, revealing results in alignment with what is already reported in the literature for similar materials in the case of UdP-20, while UdP-21, UdP-22 and UdP-23 exhibited moderate CO2 adsorption, due to transition to denser phases upon activation
Computational Design, Synthesis, and Mechanochromic Properties of New Thiophene-Based pi-Conjugated Chromophores
No full textThe possibility of exploiting supramolecular architectures for the preparation of innovative mechano- chromic devices has been extended by designing novel thienyl-substituted 1,4- bis-(ethynyl)benzene dyes, which are characterized by a conjugated, rigid, rodlike core structure. This new family of chromophores was synthesized ac- cording to a simple two-step sequential cross-coupling reaction, and the optical properties were investigated in solution and in a polymeric matrix. To tune the mechanochromic performances in smart polymer materials, a virtual screening was set up that was able to select a derivative with optimal spectral features. The effective combination of experimental and computational inves- tigations allowed us to spot those ho- mologues with already potential aniso- tropic and aggregachromic features and characterized by the best spectral prop- erties and luminescent response. The best candidate was synthesized and dis- persed into a polyethylene matrix, indeed achieving an “in silico de- signed” mechanochromic material. Be- sides the specific applications of this novel material, the integration of com- putational and experimental techniques reported here defines an efficient pro- tocol that can be applied to make a se- lection among similar dye candidates, which constitute the essential respon- sive part of such supramolecular devices
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Ligand-free Pd/Ag-mediated dehydrogenative alkynylation of imidazole derivatives
No full textA variety of 2-alkynyl(benzo)imidazoles have been synthesized by dehydrogenative alkynylation of (benzo)imidazoles with terminal alkyne in NMP under air in the presence of Ag2CO3as the oxidant and Pd(OAc)2as the catalyst precursor. The data obtained in this study support a reaction mechanism involving a non-concerted metalation deprotonation (n-CMD) pathway
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Molecular profiling of microinvasive breast cancer microenvironment progression
Get PDFBackground: Tumors develop by progression through a series of stages. Every cell of the tumor microenvironment is constantly changing in the flow of the cancer progression. It has become clear in recent years that stroma is essential for tumor maintenance and growth. Here, we aimed to give a chronological order of gene expression changes given in the dynamical framework of microinvasive breast cancer microenvironment. Methods: RNA-seq was performed on seven microinvasive breast cancers. For each of them we microdissected seven different portions of the tumor, four related to the breast epithelium and three to the stroma. Breast epithelium was chronologically subdivided in normal breast epithelium (NBE), carcinoma in situ (CIS), emerging invasive fingers (EIF) and invasive breast cancer (IBC). For each of the breast epithelium subdivisions we collected the adjacent stroma (S): S-NBE, S-EIF and S-IBC. Results: The overall differentially expressed genes (DEGs) in all the compartments were analysed and evaluated to understand the pathways involved in tumor progression. Then we analysed the DEGs of the epithelial and stromal portions in comparison with the normal portions. We observed that the stromal cells are necessary for the development and the maintenance of the tumor, especially in tumor progression. Moreover the most important genes involved in the main metabolic pathways were analysed and the communications within the different cell compartments were highlighted. Conclusions: As a future perspective, a deeply study of the identified key genes, particularly in the stromal cells, will be crucial to develop an anticancer therapy that is undergoing a conversion from a cancer cell-centric strategy to a stroma-centric strategy, more genomically stable
Self-Assembled Amphiphilic Fluorinated Random Copolymers for the Encapsulation and Release of the Hydrophobic Combretastatin A-4 Drug
Get PDFWater-soluble amphiphilic random copolymers composed of tri(ethylene glycol) meth-acrylate (TEGMA) or poly(ethylene glycol) methyl ether methacrylate (PEGMA) and perfluoro-hexylethyl acrylate (FA) were synthesized by ARGET-ATRP, and their self-assembling and ther-moresponsive behavior in water was studied by dynamic light scattering (DLS) and UV-vis spec-troscopy. The copolymer ability to self-fold in single-chain nano-sized structures (unimer micelles) in aqueous solutions was exploited to encapsulate Combretastatin A-4 (CA-4), which is a very hy-drophobic anticancer drug. The cloud point temperature (Tcp) was found to linearly decrease with increasing drug concentration in the drug/copolymer system. Moreover, while CA-4 was preferen-tially incorporated into the unimer micelles of TEGMA-ran-FA, the drug was found to induce mul-ti-chain, submicro-sized aggregation of PEGMA-ran-FA. Anyway, the encapsulation efficiency was very high (≥81%) for both copolymers. The drug release was evaluated in PBS aqueous solutions both below and above Tcp for TEGMA-ran-FA copolymer and below Tcp, but at two different drug loadings, for PEGMA-ran-FA copolymer. In any case, the release kinetics presented similar profiles, characterized by linear trends up to ≈10–13 h and ≈7 h for TEGMA-ran-FA and PEGMA-ran-FA, respectively. Then, the release rate decreased, reaching a plateau. The release from TEG-MA-ran-FA was moderately faster above Tcp than below Tcp, suggesting that copolymer ther-moresponsiveness increased the release rate, which occurred anyway by diffusion below Tcp. Cy-totoxicity tests were carried out on copolymer solutions in a wide concentration range (5–60 mg/mL) at 37 °C by using Balb/3T3 clone A31 cells. Interestingly, it was found that the concentra-tion-dependent micro-sized aggregation of the amphiphilic random copolymers above Tcp caused a sort of “cellular asphyxiation” with a loss of cell viability clearly visible for TEGMA-ran-FA solutions (Tcp below 37 °C) with higher copolymer concentrations. On the other hand, cells in contact with the analogous PEGMA-ran-FA (Tcp above 37 °C) presented a very good viability (≥75%) with respect to the control at any given concentration
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
COOLSUN: a preliminary study of “cool” properties of organic pigments
Get PDFApproximately 50% of the solar energy reaching the earth is emitted in the near infrared region (NIR), not detectable by human eye. The absorption by an object in the NIR causes an increase of its temperature1.
The pigments that interact with the NIR portion of the solar spectrum (i.e. between 700 and 1600 nm) without absorbing it are called NIR-reflecting, and their use reduces the heating of the treated substrates2. The NIR-reflective property is useful in applications where solar heating must be attenuated, such as leather goods, greenhouse coverings ,roofing and transporting of heat-sensitive materials3. Today, NIR reflectivity is obtained with the use of inorganic pigments (TiO2, metal oxides and complexes) that are expensive and, in some cases, toxic1. The key to obtain innovative coatings is then the production of organic NIR-reflective pigments to overcome problems related to costs, environmental impact, efficiency and color index of the current inorganic pigments on the market4. The goal of our work is the development of innovative products containing organic-based NIR reflective and/or NIR transparent pigments. In this preliminary phase of our project we focused on the study of the "cool" properties of commercial pigments in order to be able to design and develop thermo- and photostable organic pigments, able to reflect the radiation in the NIR. The pigments were initially dispersed in a polymeric matrix, the produced mixture was applied on white (maximum reflectance) and black (maximum absorption) test panels. The percentage reflectance of two test panels (black and white) for each pigment was determined using a UV-Vis-NIR spectrophotometer. The pigment/matrix mixtures were then applied on leather samples for the determination of the cool properties through the use of a thermal imaging camera
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