Physico-chemical and structural characterization of mucilage isolated from seeds of Diospyros melonoxylon Roxb.

Mucilagem foi isolada de sementes de Diospyros melanoxylon Roxb, uma planta que cresce naturalmente nas florestas da Índia. Vários métodos físico-químicos, como análise de partículas, microscopia electrônica, calorimetria diferencial de varredura, análise térmica diferencial, análise termogravimétrica, massa molecular por cromatografia de permeação em gel, viscosidade, análise elementar, espectrometria de difração de raios-x, potencial zeta, espectroscopia no infravermelho com transformada de Fourier, 1D (1H e 13C) (NMR) foram utilizados no presente estudo para caracterizar essa goma. A análise de partículas sugere que a mucilagem tem tamanho de partícula em nm. A análise SEM sugere que a mucilagem tem tamanho de partícula irregular. Observou-se temperatura de transição vítrea da goma de 78 °C e 74 °C por DSC e DTA, respectivamente. A análise termogravimétrica sugeriu que a mucilagem possuía boa estabilidade térmica, com duas fases de decomposição. A massa molecular da mucilagem foi 8760, por meio de cromatografia de permeação em gel, enquanto que a viscosidade foi 219,1 cP. O padrão de DRX da mucilagem indicou natureza completamente amorfa. Os principais grupos funcionais identificados a partir do espectro de FT-IR foram: 3441 cm-1 (-OH), 1632 cm-1 (-COO-), 1414 cm-1 (-COO-) e 1.219 cm-1 (CH3CO-). As análises de mucilagem por cromatografia em papel e 1D RMN indicaram a presença de açúcares.Mucilage was isolated from the seeds of Diospyros melonoxylon Roxb., a plant growing naturally in the forests of India. Various physico-chemical methods like particle analysis, scanning electron microscopy, differential scanning calorimetry, differential thermal analysis, thermogravimetry analysis, molecular weight by gel permeation chromatography, rheometry, elemental analysis, x-ray diffraction spectrometry, zeta potential, fourier transform infrared spectroscopy, 1D(1H and 13C) (NMR) have been employed to characterize this gum in the present study. Particle analyses suggest that mucilage had particle size in nanometer. SEM analysis suggested that the mucilage had irregular particle size. The glass transition temperature of the gum observed was 78 °C and 74 °C by DSC and DTA respectively. The Thermogravimetry analysis suggested that mucilage had good thermal stability with two stage decomposition. The molecular weight of mucilage was determined to be 8760, by gel permeation chromatography, while the viscosity of mucilage was observed to be 219.1 cP. The XRD pattern of the mucilage indicated a complete amorphous nature. Elemental analysis of the gum revealed specific contents of carbon, hydrogen, nitrogen and sulfur. The major functional groups identified from FT-IR spectrum include 3441 cm-1 (-OH), 1632 cm-1 (-COO-), 1414 cm-1 (-COO-) and 1219 cm-1 (-CH3CO). Analysis of mucilage by paper chromatography and 1D NMR indicated the presence of sugars

In vivo mucoadhesive strength appraisal of gum Manilkara zapota

Mucilagem (MMZ) extraída das sementes de Manilkara zapota(Linn.) P. Royen syn utilizando técnicas de maceração foi avaliada por sua força mucoadesiva por vários métodos in vitro e in vivo. O resultado mostrou que a força mucoadesiva das sementes mucilaginosas tem propriedade comparável aos polímeros naturais e sintéticos, tais como goma Guar e hidroxipropilmetil celulose (HPMC E5LV) nas condições experimentais utilizadas neste estudo. Brevemente, se pode concluir que a mucilagem de semente de Manilkara zapota pode ser usada como um excipiente farmacêutico em sistemas de liberação de fármacos mucoadesivos por via oral. Pode ser apropriado o estudo posterior de mudanças nessas propriedades após modificações químicas.The mucilage (MMZ) extracted from the seeds of Manilkara zapota(Linn.) P. Royen syn. using maceration techniques was evaluated for mucoadhesive strength by various in vitro and in vivo methods. The result showed that mucoadhesive strength of seeds mucilage have comparable property toward natural and synthetic polymers such as Guar Gum and hydroxyl propyl methyl cellulose (HPMC E5LV) under the experimental conditions used in this study. Briefly, it could be concluded that the seed mucilage of Manilkara zapota can be used as a pharmaceutical excipient in oral mucoadhesive drug delivery systems. Further, it may be appropriate to study the changes in these properties after chemical modifications

The Global Health Classroom: Collaborative Global Health Learning between New Zealand and Samoan Medical Students in a Virtual Classroom

Background Global Health is recognised as an essential component of undergraduate medical curricula to equip future doctors with the relevant knowledge, attitudes, and skills to practice in a globalised world. The Global Health Classroom (GHCR), the subject of this research project, has been developed at the Otago Medical School (OMS), New Zealand in collaboration with medical schools in Samoa and Nepal. The aim of the GHCR is to promote collaborative global health learning between medical students in different countries in a virtual classroom. In 2016, GHCR pilot studies were conducted between the partner schools and formed the basis of this Bachelor of Medical Science (Honours) Research Project in 2017. In 2017, the GHCR was conducted between the OMS, Patan Academy of Health Sciences, Nepal (PAHS), and the School of Medicine, National University of Samoa, Samoa (NUS). Data collected from the GHCR participants at OMS and NUS were included in this thesis. At NUS, GHCR was integrated into the Year 4 and 5 medical curricula. At OMS, GHCR was integrated into the Year 5 Paediatrics Module at the University of Otago, Christchurch (UOC) and Year 4 Public Health Module at the Dunedin School of Medicine, Dunedin (DSM). Aim The aim of this study was to explore the self-reported learning outcomes and experiences of New Zealand and Samoan medical students in the GHCR, and ascertain the key elements contributing to their learning and experiences. Methods A census sample of UOC, DSM and NUS students who undertook the GHCR were invited to be participants in this research. Written, informed consent was obtained from students prior to their participation in this study. A mixed-methods approach was developed using a questionnaire for all participants, and semi-structured interviews for participants selected by random sampling following participation in the GHCR. The questionnaire had a range of Likert-type scale and open-ended questions. Quantitative data were descriptively analysed using SPSS Version 23 and qualitative data were thematically analysed. A triangulation approach informed the synthesis of the data. Results Of the participants, 85% (74/87) responded to the post-GHCR questionnaire. Nineteen interviews were conducted: six each with UOC and NUS students, and seven with DSM students. Students reported gaining knowledge about patient care, healthcare systems, and the culture and determinants of health, in their partner country. There was evidence that attitudes such as cultural understanding and respect, curiosity and interest, humility and vision for progress were encouraged among students by their GHCR experiences. Reported outcomes in the GHCR align favorably with the recommended global health learning concepts in the literature. Key elements for success in the GHCR were found to be: clinical cases and global health-themed guiding questions; teachers as facilitators and students as self-directed learners; peer learning and social interaction; and video-conferencing. Students’ experiences in the GHCR were largely positive. Students found learning with their international peers in a virtual classroom made learning about global health “more real and tangible” and “much more accessible than learning [about global health] on a purely theoretical basis.” Internet connectivity during video-conferencing and competing demands such as assignments, clinical teaching and assessments could at times be barriers limiting student engagement in the GHCR. Conclusion The findings in this study suggest that the GHCR presents a promising global health learning model embodying core values of partnership, collaboration and reciprocity between medical students and institutions in different countries

Fibre reinforced mortar application for out-of-plane strengthening of schist walls

The aim of the present work is to assess the effectiveness of an innovative strengthening technique for the rehabilitation of masonry buildings deficiently prepared to resist to loading conditions typical of seismic events. This technique is based on the application of outer layers of fibre reinforced mortar (FRM) by spray technology and it is used for increasing the load carrying capacity and deformation ability of masonry elements. For this purpose three almost real scale schist walls prototypes were strengthened and tested. The experimental program is described and the relevant results are presented and discussed. For estimating the properties of the schist walls and FRM taking into account the application conditions, the tested prototypes were simulated with a FEM-based computer program that has constitutive models for the simulation of the nonlinear behaviour of these materials. By using the derived properties, a parametric study was conducted to identify the influence of the FRM properties on the performance of the proposed strengthening system.The author wish to acknowledge CiviTest, Lda (Jesufrei, Portugal) for supporting the experimental program, the sustain provided by INOTEC - Innovative material of ultra-high ductility for the rehabilitation of the built patrimony, QREN project number 23024, and the collaboration of the companies Owens Corning, Exporplas, Sika, Chryso and SECIL for providing, respectively, glass fibres, polypropylene fibres, superplasticizers, Viscous Modifier Agent, and Cement. The authors further wish to acknowledge the Erasmus Plus and Placement Mobility Programs among the University of Ferrara (Italy), the University of Minho (Portugal) and the CiviTest Lda (Portugal) which made this international cooperation possible

A VALIDATED STABILITY-INDICATING REVERSE-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR DACLATASVIR, IDENTIFICATION AND CHARACTERIZATION OF DEGRADATION PRODUCTS USING LC-ESI-QTOF-MS

Objective: The objective of this study was to report the stability of antiviral drug, daclatasvir (DCV) based on the information obtained from forced degradation studies and characterization of degradation products (DPs) by tandem mass spectrometry (MS/MS) analysis. Methods: Chromatographic separation was achieved on Shimadzu liquid chromatography (LC) 20 AD high-performance LC system with photodiode array detector having Kromasil C18 (250 mm×4.6 mm×5 μm) with isocratic elution of a mobile phase composed of ammonium acetate buffer (pH 4.5) and acetonitrile in a ratio of 50:50 at 315 nm. The drug was subjected to forced hydrolytic, oxidative, photolytic, and thermal stress in accordance with the ICH guideline Q1A (R2). The drug showed degradation under acidic and basic hydrolytic conditions by forming two DPs. The DPs were characterized using LC– MS/MS studies and the pathways of fragmentation are proposed. Validation of the developed method was carried out in accordance with ICH guidelines. Results: Two DPs were identified, DP-1 as (S)-1-((S)-2-(5-(4’-(2-((S)-1-((S)-2-((methoxycarbonyl)amino)-3-methylbutanoyl)pyrrolidin-2-yl)-1H-imidazol-5-yl)-[1,1’-biphenyl]-4-yl)-1H-imidazol-2-yl)pyrrolidin-1-yl)-3-methyl-1-oxobutan-2-aminium and DP-2 as (S)-2-(5-(4’-(2-((S)-1-((S)-2- ((methoxycarbonyl)amino)-3-methylbutanoyl)pyrrolidin-2-yl)-1H-imidazol-5-yl)-[1,1’-biphenyl]-4-yl)-1H-imidazol-2-yl)pyrrolidin-1-ium. Conclusion: The method proved to be simple, accurate, precise, specific, robust, and less time consuming and can be applied for the determination of DCV in bulk and marketed formulation

Sintering of nanocrystalline silicon carbide in plasma pressure compaction system

Nanostructured ceramics offer significant improvements in properties over the corresponding materials with grain sizes on the order of tens to hundreds of microns. Silicon carbide (SiC) is an important structural ceramic whose properties can potentially be enhanced due to nanoscale microstructures. It has been suggested that SiC samples with grain sizes on the order of a few hundred nanometers can result in significant improvements in flexural strength, chemical resistance, thermal stability and electrical resistivity. To realize these properties, it is important to be able to sinter SiC powder to full density while avoiding exaggerated grain growth. Hence, sintering behavior and microstructural evolution in nanocrystalline SiC has been investigated in this study. Nanocrystalline SiC samples (average size ~ 70 nm) were fabricated in a plasma pressure compaction (PC) system, a novel sintering technique. Master Sintering Curve (MSC) analysis was used to correlate the densification in SiC to the amount of work put into the system. MSC as a function of pressure for were generated. The activation energy, Q, for sintering was determined for three different pressures of 10, 30 and 50 MPa and found to be 1666, 1034 and 1162 kJ/mol, respectively. The variation of Q with pressure was reasoned to be an effect of various competing mechanisms. Taguchi analysis was used to study the effect of sintering parameters such as time, temperature, pressure and heating rate on the properties of the sintered part such as density, hardness and fracture toughness. Optimal operating conditions were determined and it was also found that each parameter affected the final properties almost equally. Complete densification of SiC samples was achieved at 1600 °C which is ~150 °C lower than reported in the literature for other sintering techniques

Identification, Isolation and Characterization of Unknown Degradation Products of Cefprozil Monohydrate by HPTLC

The present research work was aimed to determine stability of cefprozil monohydrate (CEFZ) as per various stress degradation conditions recommended by International Conference on Harmonization (ICH) guideline Q1A (R2). Forced degradation studies were carried out for hydrolytic, oxidative, photolytic and thermal stress conditions. The drug was found susceptible for degradation under all stress conditions. Separation was carried out by using High Performance Thin Layer Chromatographic System (HPTLC). Aluminum plates pre-coated with silica gel 60F254 were used as the stationary phase. The mobile phase consisted of ethyl acetate: acetone: methanol: water: glacial acetic acid (7.5:2.5:2.5:1.5:0.5v/v). Densitometric analysis was carried out at 280 nm. The system was found to give compact spot for cefprozil monohydrate (0.45 Rf). The linear regression analysis data showed good linear relationship in the concentration range 200-5.000 ng/band for cefprozil monohydrate. Percent recovery for the drug was found to be in the range of 98.78-101.24. Method was found to be reproducible with % relative standard deviation (%RSD) for intra- and inter-day precision to be < 1.5% over the said concentration range. The method was validated for precision, accuracy, specificity and robustness. The method has been successfully applied in the analysis of drug in tablet dosage form. Three unknown degradation products formed under various stress conditions were isolated by preparative HPTLC and characterized by mass spectroscopic studies

Wall-to-horizontal diaphragm connections in historical buildings: A state-of-the-art review

Wall-to-horizontal diaphragm connections play a crucial role in the global stability of historical buildings under seismic actions. When these links are ineffective or absent, engineered measures should be considered to enhance the earthquake-resistant box-type behavior. Besides the great variety on the construction systems and materials, common damages were observed in recent seismic events showing the high vulnerability of local mechanisms promoted by the lack of structural integrity. Although the acknowledged importance of connections, this topic has been practically neglected over time among the research community and practitioners and only few of them focused on the influence of diaphragm-to-wall connections on the dynamic behavior of the building as a whole.This paper presents a literature review of the traditional wall-to-floor or wall-to-roof connections in unreinforced masonry buildings and summarizes typical and innovative strengthening solutions, taking into account the indications provided by the few design codes addressing this topic. Experimental laboratory researches are investigated, including shaking table tests on global and local scale, and cyclic or monotonic tests to characterize anchoring systems. An overview of the typical vulnerability assessment approaches and modelling techniques is given, considering present standards that account for connections.This work was partly financed by FEDER funds through the Operational Programme Competitiveness Factors (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. The financial support of FCT to the first author, through the PhD grant SFRH/BD/131652/2017, is also acknowledged

ONE-SIDED rocking analysis of corner mechanisms in masonry structures: Influence of geometry, energy dissipation, boundary conditions

The corner mechanism in masonry structures is one of the out-of-plane modes that may frequently occur under dynamic actions such as earthquakes. The three dimensional motion, in principle complex to treat, can be simplified into a two-dimensional problem, where a prismatic equivalent block is associated to the corner mechanism. This paper provides a method to treat the corner mechanism in two dimensional rocking analysis, taking into account the roof actions especially the roof thrust that acts as destabilizing force in the preliminary phases of motion and the boundary conditions such as the transverse walls. A case study is taken as benchmark to perform rocking non-linear analyses and discuss the role of geometry, energy dissipation and boundary conditions. It is shown the relevant influence of the geometry and of the coefficient of restitution on the stability conditions, whenever the oscillation produce horizontal displacement values of some cm. The results of the case study, subjected to the Central Italy earthquake, are compared to the actual response of the corner mechanism, which collapsed during this seismic swarm, showing that the rocking analysis on the equivalent block correctly predicts the collapse occurred.The Authors thank the Italian Department of Civil Protection and the Consortium RELUIS (2018) for funding this research activity. This work was partially financed by FEDER funds through the Competitiveness Factors Operational Program - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633