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Experiments were performed to characterize the pH, gelation time, diffusion processes, material properties, adhesive properties, and the drying variables on the material and adhesive properties of Gelatin Resorcinol Dialdehyde (GR-DIAL) tissue adhesives by varying formulation. Three adhesive formulations with altered weight content of water and glyoxal (a dialdehyde) were utilized. The adhesive formulations were characterized by pH and gelation time in situ, and absorption/desorption of water in the formed resin. Thermal analysis, mechanical testing, and lap shear adhesive bond testing were utilized to characterize fresh GR-DIAL adhesive formulations and formulations dried at 370C. From the results, the diffusion processes, material and adhesive properties of the adhesive formulations were primarily affected by hydrogen bonding, chemical cross-linking, and the existence of bound water within the bulk adhesive. Formulations with increased glyoxal content had both a higher degree of cross-linking and proportion of bound water within the bulk adhesive. The increased number of chemical cross-links greatly increased the swelling resistance of the adhesives, while, the existence of bound water within the adhesive increased the resistance to drying, and plasticized the resin by depressing the resin glass transition temperature, and increased the adhesive ductility. Hydrogen bonding increased with increased gelatin content or decreased water content, resulting in increased strength and modulus of the adhesives as well as increased adhesive strength. / Master of Science

no / The two known crystalline phases of resorcinol and their phase transitions are of considerable interest. The crystals exhibit pyro- and piezo-electricity and, remarkably, the higher temperature phase is the denser phase. Furthermore, crystals of the phase, by virtue of having a polar axis, have played a crucial role in investigating fundamental issues of crystal growth. We report an optimized force field for the molecular simulation of crystalline phases of resorcinol. The hydroxyl groups of the resorcinol molecule have a torsional degree of freedom and the molecule adopts a different conformation in each of the two phases of resorcinol. The torsional barrier, therefore, was considered to be critical and has been characterized using ab initio methods. Although the atomic partial charges showed some dependence on the molecular conformation, a single set of partial charges was found to be sufficient in describing the electrostatic potential for all conformations. The parameters for the van der Waals interactions were optimized using sensitivity analysis. The proposed force field reproduces not only the static structures but also the stability of the crystalline phases in extended molecular dynamics simulations.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Resorcinarenes are tetramers, belonging to a class of [1]4metacyclophanes, easily formed by the acid- or base-catalysed condensation of resorcinol and aldehydes. Properties include, amongst others; bowl-like shape, adhesion to hydrophilic surfaces and formation of hexameric capsules. Their uses are, to mention some: components in liquid crystals, photoresistors, selective membranes, surface reforming agents, HPLC stationary phases, ion-channel mimics, metal-ion extraction, molecular switches and ligands for metal catalysts. Selective functionalization of resorcinarenes has been explored and achieved via relatively inefficient methodologies which limit studies, structural architecture and new applications. In this work, synthesis of C4v symmetric resorcinarene ethers was performed which were used as templates in undertaking studies towards selective derivatisation of resorcinarenes via an ortholithiation approach. Conditions for the efficient synthesis of distally substituted resorcinarenes using ortholithiation were optimized and tested with a range of electrophiles, lower rim lengths, scale, base equivalents, reaction times and solvent effects. Ortholithiation gave distally substituted resorcinarenes in reasonable yields (>80%). Ortholithiation and its ability to form distal-resorcinarene esters could possibly be used as a way to synthesize distal-chloromethyl resorcinarene precursors whose further functionalization would furnish a range of distal-resorcinarene imidazolium salts, a class of distal bidentate carbene ligand staring materials for transition metal coordination. / AFRIKAANSE OPSOMMING: Resorsinarene is sikliese tetramere, wat deel uitmaak van 'n klas van [1]4metasiklofane, en kan maklik gevorm word deur die suur- of basis-gekataliseerde kondensasie van resorsinol en aldehiede. Eienskappe sluit onder andere in: bak-vormig, adhesie aan hidrofiliese oppervlakke en die vormasie van heksameriese kapsules. Tipiese voorbeelde van gebruike sluit die volgende in: komponente van vloeistof kristalle, fotoresistors, selektiewe membrane, oppervlak hervormings agente, HDVC stationêre fases, ioon-kanaal nabootsers, metaal-ioon ekstraksie, molekulêre skakelaars en ligande vir metaalkatalise. Selektiewe funksionalisering van resorsinarene was al voorheen bestudeer, maar die metodologieë was beperkend ten opsigte van die struktuele argitektuur en nuwe toepassings wat daaruit gekom het. In hierdie werk was C4v simmetriese resorsinareen eters gesintetiseer wat gebruik was as uitgangstowwe om selektiewe funksionalisering deur orto-litiëring te bewerkstellig. Kondisies vir die effektiewe sintese van distaal gesubstitueerde resorsinarene, deur gebruik te maak van orto-litiëring, was bepaal en ge-optimaliseer deur gebruik te maak van 'n wye reeks elektrofiele, laer rand lengtes, reaksieskale, basis ekwivalente en reaksie tye. Deur dié proses was dit moontlik om distaal gesubstitueerde resorsinareen produkte te bekom in redelike opbrengste (>80%) met meeste funksionele goepe. Daar word voorsien om orto-litiëring, en sy vermoë om distale-resorsinareen esters te vorm,van gebruik te maak as 'n beginpunt in die sintese van distale-chlorometiel resorsinarene, wat op hulle beurt weer sal dien as uitgangstowwe vir die sintese van distale-resorsinareen imidasolium soute. Hierdie distale, bidentale soute kan gebruik word as karbeen ligande in oorgangsmetaal koordinasie.

This research mainly includes two parts. First, monodispersed silica spheres with diameter about 58 and 73 nm were successfully synthesized. The tablet-like silica template could be made using a stainless steel mold by pressing the mold with a pressure ~ 10 MPa. The advantage of this molding process is it takes only a short time to accomplish the total fabrication. Second, infiltration of the carbon precursor was done using the monomers resorcinol (R) and furfural (F) in the interval of tablet-like silica template, and then polymerization and drying. It was subsequently carbonized in N2 atmosphere at 800 ¢J and then the silica template was removed by 20 wt % HF solution. The activated porous carbon material has larger specific surface area than the traditional powder carbon material. The chemical activation process by KOH plays a vital role in raising the specific surface area, since the KOH would etch the carbon pore surface to produce a large number of micropores (diameter < 2 nm), forming a macro-micro or meso-micro porous carbon materials. The F/R molar ratios for polymerization between 2.0 to 3.0 were applied and the carbon yields of these resins were higher than 51% in this range. An F/R ratio below 2.0 or 3.0 gave a lower carbon yield when carbonization at 800 ¢J. X-ray diffraction analyses on the macroporous carbon materials indicate a semi-crystalline structure which belong to the hexagonal crystal system with (002) d-spacing of = 0.373 nm, which is larger than the 0.339 nm of graphite. In Raman spectra analysis, the integral area of D-peak (ID) and G-peak (IG) is an index to define the degree of graphitization. The ratios ID/IG of lie between 1.7 - 1.8, which are larger than that of graphite (ID/IG = 0.1 - 0.3), so the FR series macroporous carbon is mostly amorphous and is far from highly crystallized structure. The un-activated macroporous carbon materials has open pore structure, the pore diameter is 56 nm which is classified to the macroporous scale. The nitrogen adsorption/desorption isotherm of the porous carbon materials belongs to the type IV, with H1 type hysteresis. The BET results show that the specific surface area increases with increasing KOH concentration; whereas the open pore structure remain the same. SEM observations reveal the pore structure doesn¡¦t collapse but the pore wall does become thinner. From this work, macroporous carbon materials with total pore volume as high as 2.23 cm3/g and the specific surface area as high as 658 m2/g have successfully been synthesized. Activation by KOH creates more micropores on its carbon walls, resulting in a macro-microporous carbon material having two scales of pores in the same time and with a high surface area of 1404 m2/g.

No description available.

Os \"peelings\" químicos são formulações esfoliantes utilizadas na terapêutica de queratoses actínicas, rugas, discromias pigmentares, acne vulgar e rosácea. A solução de Jessner (SJ) é amplamente usada como agente em peelings químicos. Na presente pesquisa foram empregadas formulações farmacêuticas de SJ como amostras para a determinação quantitativa simultânea das substâncias ativas. A solução alcoólica é composta de resorcinol (14%), ácido salicílico (14%) e ácido láctico (14%). Duas amostras de gel são compostas de resorcinol (30%) e ácido salicílico (20%), respectivamente. Foram desenvolvidos e validados métodos espectrofotométricos na primeira e segunda derivada no UV para a quantificação de ácido salicílico e resorcinol, respectivamente na SJ, utilizando etanol como branco e foram desenvolvidos métodos espectrofotométricos na primeira derivada no UV para a quantificação de resorcinol e ácido salicílico nas amostras em gel, utilizando ácido sulfúrico 0,1 N como branco. Quando o etanol foi utilizado como branco, as curvas de calibração foram lineares em uma faixa de concentração de 22,0 a 34,0 &#181;g/mL (resorcinol) e de 12,0 a 24,0 &#181;g/mL (ácidos salicílico), para os métodos na segunda e primeira derivada no UV (usando etanol como branco), ambos com coeficientes de correlação de 0,9999. Quando o ácido sulfúrico 0,1N foi utilizado como branco, as curvas de calibração foram lineares em uma faixa de concentração de 18,0 a 42,0 &#181;g/mL (resorcinol) e de 8,0 a 32,0 &#181;g/mL (ácido salicílico), para o método na primeira derivada no UV com coeficientes de correlação de 0,9999 e 0,9998 respectivamente. Os resultados nas amostras alcoólicas de SJ (amostras A e B) foram 104,4% de resorcinol (DPR 0,83%) e 103,2% de ácido salicílico (DPR 0,68%) enquanto que nas amostras em gel (amostras E e F) foram 101,9% de resorcinol (DPR 0,34%) e as amostras em gel C e D, 100,7% de ácido salicílico (DPR 0,28%). / Chemical peelings are exfoliating formulations used in the treatment of actinic keratosis, wrinkles, dyschromies, acne vulgaris and rosacea acne.The Jessner Solution (JS) sample is widely used as chemical peeling agent. In this research we selected a JS pharmaceutical preparation for simultaneous quantitative determination of the active components. The alcoholic solution sample is composed of resorcinol (14%), salicylic acid (14%) and lactic acid (14%); two gel samples are composed of resorcinol (30%) and salicylic acid (20%), respectively. First and second derivative UV spectrophotometric methods were developed and validated for quantitative determination of salicylic acid and resorcinol, respectively. In JS alcoholic solution, ethanol was used as background. A first derivative UV spectrophotometric method was developed for quantitative determination of resorcinol and salicylic acid in gel samples using 0.1N sulfuric acid as background. Calibration curves were linear within a concentration range from 22.0 to 34.0 &#181;g/mL (resorcinol) and from 12.0 to 24.0 &#181;g/mL (salicylic acid), for second and first derivative UV spectrophotometric method (ethanol as background) with a correlation coefficients of 0.9999 and 0.9999, respectively. Calibration curves were linear within a concentration range from 18,0 to 42,0 &#181;g/mL (resorcinol) and from 8.0 to 32.0 &#181;g/mL (salicylic acid), for first derivative UV spectrophotometric method (0.1N sulfuric acid as background) with correlation coefficients of 0.9999 and 0.9998, respectively. The alcoholic samples of JS (sample A and B) presented 104.4% of resorcinol (RSD 0.83%) and 103.2% of salicylic acid (RSD 0.68%) while the gel samples (sample E and F) presented 101.9% of resorcinol (RSD 0.34%) and gel sample C and D, 100.7% of salicylic acid (RSD 0.28%).

Os \"peelings\" químicos são formulações esfoliantes utilizadas na terapêutica de queratoses actínicas, rugas, discromias pigmentares, acne vulgar e rosácea. A solução de Jessner (SJ) é amplamente usada como agente em peelings químicos. Na presente pesquisa foram empregadas formulações farmacêuticas de SJ como amostras para a determinação quantitativa simultânea das substâncias ativas. A solução alcoólica é composta de resorcinol (14%), ácido salicílico (14%) e ácido láctico (14%). Duas amostras de gel são compostas de resorcinol (30%) e ácido salicílico (20%), respectivamente. Foram desenvolvidos e validados métodos espectrofotométricos na primeira e segunda derivada no UV para a quantificação de ácido salicílico e resorcinol, respectivamente na SJ, utilizando etanol como branco e foram desenvolvidos métodos espectrofotométricos na primeira derivada no UV para a quantificação de resorcinol e ácido salicílico nas amostras em gel, utilizando ácido sulfúrico 0,1 N como branco. Quando o etanol foi utilizado como branco, as curvas de calibração foram lineares em uma faixa de concentração de 22,0 a 34,0 &#181;g/mL (resorcinol) e de 12,0 a 24,0 &#181;g/mL (ácidos salicílico), para os métodos na segunda e primeira derivada no UV (usando etanol como branco), ambos com coeficientes de correlação de 0,9999. Quando o ácido sulfúrico 0,1N foi utilizado como branco, as curvas de calibração foram lineares em uma faixa de concentração de 18,0 a 42,0 &#181;g/mL (resorcinol) e de 8,0 a 32,0 &#181;g/mL (ácido salicílico), para o método na primeira derivada no UV com coeficientes de correlação de 0,9999 e 0,9998 respectivamente. Os resultados nas amostras alcoólicas de SJ (amostras A e B) foram 104,4% de resorcinol (DPR 0,83%) e 103,2% de ácido salicílico (DPR 0,68%) enquanto que nas amostras em gel (amostras E e F) foram 101,9% de resorcinol (DPR 0,34%) e as amostras em gel C e D, 100,7% de ácido salicílico (DPR 0,28%). / Chemical peelings are exfoliating formulations used in the treatment of actinic keratosis, wrinkles, dyschromies, acne vulgaris and rosacea acne.The Jessner Solution (JS) sample is widely used as chemical peeling agent. In this research we selected a JS pharmaceutical preparation for simultaneous quantitative determination of the active components. The alcoholic solution sample is composed of resorcinol (14%), salicylic acid (14%) and lactic acid (14%); two gel samples are composed of resorcinol (30%) and salicylic acid (20%), respectively. First and second derivative UV spectrophotometric methods were developed and validated for quantitative determination of salicylic acid and resorcinol, respectively. In JS alcoholic solution, ethanol was used as background. A first derivative UV spectrophotometric method was developed for quantitative determination of resorcinol and salicylic acid in gel samples using 0.1N sulfuric acid as background. Calibration curves were linear within a concentration range from 22.0 to 34.0 &#181;g/mL (resorcinol) and from 12.0 to 24.0 &#181;g/mL (salicylic acid), for second and first derivative UV spectrophotometric method (ethanol as background) with a correlation coefficients of 0.9999 and 0.9999, respectively. Calibration curves were linear within a concentration range from 18,0 to 42,0 &#181;g/mL (resorcinol) and from 8.0 to 32.0 &#181;g/mL (salicylic acid), for first derivative UV spectrophotometric method (0.1N sulfuric acid as background) with correlation coefficients of 0.9999 and 0.9998, respectively. The alcoholic samples of JS (sample A and B) presented 104.4% of resorcinol (RSD 0.83%) and 103.2% of salicylic acid (RSD 0.68%) while the gel samples (sample E and F) presented 101.9% of resorcinol (RSD 0.34%) and gel sample C and D, 100.7% of salicylic acid (RSD 0.28%).