Determination Of The Marker Compounds In Adulterated And Non-Adulterated Stingless Bee Honey Using Gc-Ms

Madu sejak dahulu lagi seringkali dicampur dengan alasan mengaut keuntungan ekonomi. Secara amnya, madu dicampurkan dengan menambah bahan asing atau digunakan untuk memberi makan lebah Honey has been adulterated since long time due to economical reason. Generally, honey is adulterated by adding the foreign substances to pure honey or used for feeding the be

A Facile Synthesis of Polypyrrole/Carbon Nanotube Composites with Ultrathin, Uniform and Thickness-Tunable Polypyrrole Shells

An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications

Tholins: A Gas Phase Computational Study of Methanimine and Related Species

Titan has been referred to as the “gem of the Solar System.” This significance comes from its dense atmosphere, which is the only atmosphere in our Solar System other than Earth’s that is dense enough to produce a hydrological cycle (or methanological cycle, in the case of Titan). Scientists in the fields of astrobiology and astrochemistry believe that Titan’s current atmospheric conditions could resemble that of the primordial Earth, and as such is being studied to further our understanding of how life forms. While Titan’s atmosphere contains an abundance of organic molecules, methanimine (MA) and it’s related species the methyl amino radical (MAR) and methyleneamine cation (MEC) are of particular interest. Scientists believe that MA, MAR, and MEC are precursors to organic aerosols called Tholins, which are defined as nitrogen-containing molecules that are thought to be precursors to amnio acids. The purpose of this research is to answer crucial questions to understand the role of these molecules in Titan’s atmospheric chemistry. To do this, a gas phase chemical model is employed. The expected outcomes of the computational work are threefold: 1) determine the major formation and destruction reactions for MA and related species, 2) obtain the most up-to-date rate coefficients for those reactions, and 3) obtain abundance versus time data for MA and related species. Tholin production is observed at most altitudes, but this research focuses on the upper atmosphere (500+ km), which has largely been unstudied until recent years. While MA, MAR, and MEC have all been studied, a comprehensive list of reactions and rate coefficients has not been completed since 2010. The data from this study suggest that MA, MAR, and MEC are present at concentrations deemed important for tholin production, and agrees with data presented by other chemical models

Design Principles for Two-Dimensional Molecular Aggregates Using Kasha's Model: Tunable Photophysics in Near and Short-Wave Infrared

Technologies which utilize near-infrared (700 – 1000 nm) and short-wave infrared (1000 – 2000 nm) electromagnetic radiation have applications in deep-tissue imaging, telecommunications and satellite telemetry due to low scattering and decreased background signal in this spectral region. It is therefore necessary to develop materials that absorb light efficiently beyond 1000 nm. Transition dipole moment coupling (e.g. J-aggregation) allows for redshifted excitonic states and provides a pathway to highly absorptive electronic states in the infrared. We present aggregates of two cyanine dyes whose absorption peaks redshift dramatically upon aggregation in water from ~800 nm to 1000 nm and 1050 nm respectively with sheet-like morphologies and high molar absorptivities (e ~ 105 M-1cm-1). We use Frenkel exciton theory to extend Kasha’s model for J and H aggregation and describe the excitonic states of 2-dimensional aggregates whose slip is controlled by steric hindrance in the assembled structure. A consequence of the increased dimensionality is the phenomenon of an intermediate “I-aggregate”, one which redshifts yet displays spectral signatures of band-edge dark states akin to an H-aggregate. We distinguish between H-, I- and J-aggregates by showing the relative position of the bright (absorptive) state within the density of states using temperature dependent spectroscopy. I-aggregates hold potential for applications as charge injection moieties for semiconductors and donors for energy transfer in NIR and SWIR. Our results can be used to better design chromophores with predictable and tunable aggregation with new photophysical properties

Nuclear tunneling effects of charge transport in rubrene, tetracene, and pentacene

The mechanism of charge transport in organic materials is still controversial from both experimental and theoretical perspectives. At room temperature, molecular deformations interact strongly with the charge carrier both through intermolecular and intramolecular phonons, suggesting a thermally activated hopping mechanism as described by the Marcus electron transfer theory. However, several experimental measurements have indicated that the electronic transport behaves in a "bandlike" manner, as indicated by a decrease in mobility with increasing temperature, in contradiction to the Marcus description. Bandlike first-principles calculations based on the Holstein-Peierls model tend to overestimate the charge mobility by about 2 orders of magnitude. Here, a hopping model is derived that not only quantitatively describes the charge mobility but also explains the observed bandlike behavior. This model uses the quantum version of charge-transfer theory coupled with a random-walk simulation of charge diffusion. The results bridge the gap between the two extreme mechanisms. This first-principles method predicts the room-temperature hole mobilities to be 2.4, 2.0, and 0.67 cm(2)/V s, for rubrene, pentacene, and tetracene, respectively, in good agreement with experiment

Documenting metrological traceability as intended by ISO 15189 : 2012: A consensus statement about the practice of the implementation and auditing of this norm element

ISO15189:2012 requires medical laboratories to document metrological traceability of their results. While the ISO17511:2003 standard on metrological traceability in laboratory medicine requires the use of the highest available level in the traceability chain, it recognizes that for many measurands there is no reference above the manufacturer's selected measurement procedure and the manufacturer's working calibrator. Some immunoassays, although they intend to measure the same quantity and may even refer to the same reference material, unfortunately produce different results because of differences in analytical selectivity as manufacturers select different epitopes and antibodies for the same analyte. In other cases, the cause is the use of reference materials, which are not commutable. The uncertainty associated with the result is another important aspect in metrological traceability implementation. As the measurement uncertainty on the clinical samples is influenced by the uncertainty of all steps higher in the traceability chain, laboratories should be provided with adequate and appropriate information on the uncertainty of the value assignment to the commercial calibrators that they use. Although the between-lot variation in value assignment will manifest itself as part of the long-term imprecision as estimated by the end-user, information on worst-case to be expected lot-lot variation has to be communicated to the end-user by the IVD provider. When laboratories use ancillary equipment that potentially could have a critical contribution to the reported results, such equipment needs verification of its proper calibration and criticality to the result uncertainty could be assessed by an approach based on risk analysis, which is a key element of ISO15189:2012 anyway. This paper discusses how the requirement for metrological traceability as stated in ISO15189 should be met by the medical laboratory and how this should be assessed by accreditation bodies.Peer reviewe

Thirty-eight-year follow-up of the first patient of mandibular reconstruction with free vascularized fibula flap

Background: The mandible is responsible for vital functions of the stomatognathic system, and its loss results in functional and aesthetic impairment. Mandibular reconstruction with free fibula flap is considered the gold standard for mandibular reconstruction. Case presentation: We describe here the 38-year follow-up of the patient who was the first case of mandibular reconstruction with free fibula flap reported in the literature. The original report describes a 27-year-old woman who had undergone extensive mandibulectomy due to an osteosarcoma. A microvascularized fibula flap was used for mandibular reconstruction in 1983. Two years later, a vestibulo-lingual sulcoplasty with skin graft was performed to allow the construction of a total dental prosthesis. Fifteen years after the initial treatment, an autologous iliac crest graft was placed in the fibula flap, aimed at increasing bone thickness and height for rehabilitation with implant supported prosthesis. In 2015, a rib graft was positioned in the mental region, enhancing the support to the soft tissues of the face and improving the oral function. A recent review of the patient shows well-balanced facial morphology and optimal functional results of the procedure. Conclusions: The fibula flap method, described in 1975 and first reported for mandibular reconstruction in 1985, continues to be applied as originally described, especially where soft tissue damage is not extensive. Its use in reconstructive surgery was expanded by advancements in surgery and techniques such as virtual surgical planning. However, there is still a lack of evidence related to the long-term evaluation of outcomes. The present work represents the longest-term follow-up of a patient undergoing mandibular reconstruction with free vascularized fibula flap, presenting results showing that, even after 38 years, the procedure continues to provide excellent results

Multiplex detection of nucleases by a graphene-based platform

In this article, we present a new method for the multiplex detection of nucleases by using graphene oxide (GO) as a platform. We introduce a Y-shaped DNA (Y-DNA) as the multiplex probe. The 5' termini of the Y-DNA are labeled with carboxy fluorescein (FAM), 6-carboxy-X-rhodamine (ROX) and cyanine 5 (Cy5) and they include three nuclease cleavage sites corresponding to PvuII, EcoRV and HaeIII, respectively. Upon the addition of nucleases, the nucleases cleave the corresponding sites in Y-DNA. Then, short dsDNA fragments containing fluorophores were released from the Y-DNA. These dsDNA fragments were unstable and easy to unwind into two short ssDNAs. They were then adsorbed onto the GO surface. Because of the excellent electronic transference of GO, the fluorescence intensity of the fluorophores can be quenched efficiently. Therefore, by monitoring the fluorophores' fluorescence change before and after the addition of the nucleases, it is easy to establish a platform of a Y-DNA/GO complex for the simultaneous multiplex detection of nucleases.National Natural Science Foundation of China[20735002, 20975023]; National Basic Research Program of China[2010CB732403]; Program For New Century Excellent Talents In University of China[09-001 4]; National Science Foundation of Fujian Province[2010J06003