Functionalization of carbon nanofibers by a Diels-Alder addition reaction

This paper reports functionalization of CNF via a Diels-Alder addition reaction and the characterization of the obtained materials. The functionalization was assessed by a calorimetric technique (DSC) and the morphology of CNF modified materials was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The functionalization was observed to be dependent on the preparative conditions. Detailed analysis of the CNF modified material surface using TEM, shows a deposited layer homogeneously distributed over the CNF structures with an average thickness of about 15 nm. Finally the chemical activity of the raw CNF and functionalized CNF was analyzed to determine the pH of the point of zero charge (pHpzc) values. The results obtained showed that the functionalized CNF materials presented enhanced acid activity comparatively with the modified carbonaceous materials reported in literature.     

Graphene phytotoxicity in the seedling stage of cabbage, tomato, red spinach, and lettuce

The effects of graphene on root and shoot growth, biomass, shape, cell death, and reactive oxygen species (ROS) of cabbage, tomato, red spinach, and lettuce, were investigated using a concentration range from 500 to 2000 mg/L. The results of the combined morphological and physiological analyses indicate that after 20 days of exposure under our experimental conditions, graphene significantly inhibited plant growth and biomass compared to a control. The number and size of leaves of the graphene-treated plants were reduced in a dose-dependent manner. Significant effects also were detected showing a concentration-dependent increase in ROS and cell death as well as visible symptoms of necrotic lesions, indicating graphene-induced adverse effects on cabbage, tomato, and red spinach mediated by oxidative stress necrosis. Little or no significant toxic effect was observed with lettuce seedlings under the same conditions. The potential effect of graphene largely depends on dose, exposure time, and plant species and deserves further attention.     

Crosslinking of poly(N‐vinyl‐2‐pyrrolidone) in the coating of cotton yarn

Coating of cotton yarn is employed in the textile industry to increase the mechanical resistance of the yarns and resistance to vibration, friction, impact, and elongation, which are some of the forces to which the yarn is subjected during the weaving process. The main objective of this study is to investigate the usage of a synthetic hydrophilic polymer, poly(N‐vinyl‐2‐pyrrolidone) (PVP), to coat 100% cotton textile yarn, aiming to give the yarn a temporary mechanical resistance. For the improvement of the mechanical resistance of the yarn, the following crosslinking processes of PVP were investigated: UV‐C (ultraviolet) radiation, the Fenton and photo‐Fenton reactions, and sensitized UV‐C radiation. The influence of each crosslinking process was determined through tensile testing of the coated yarns. The results indicated that the best crosslinking process employed was UV‐C radiation; increasing the mechanical resistance of the yarn up to 44% if compared with the pure cotton yarn, that is, without polymeric coating and crosslinking. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.     

Dechlorination of endocrine disrupting chemicals using Mg 0/ZnCl 2 bimetallic system

In the present study, Mg⁰/ZnCl₂ bimetallic system was evaluated for its efficiency to dechlorinate endosulfan and lindane in aqueous phase. Presence of acetone in the reaction mixture played an important role by increasing the solubilities of both pesticides and thereby accelerating its mass transfer. Water acetone ratio of 2:1 and 1:1 (v/v) was found optimum for the dechlorination of endosulfan and lindane respectively. Presence of H⁺ ions in the reaction mixture (50 μl ml⁻¹ of glacial acetic acid) accelerated the degradation efficiency of 30 ppm initial concentration of endosulfan (96% removal) and lindane (98% removal) at Mg⁰/ZnCl₂ dose of 5/1 mg ml⁻¹ within 30 min of reaction. Dechlorination kinetics for endosulfan and lindane (10, 30 and 50 ppm initial concentration of each pesticide) with varying Mg⁰/ZnCl₂ doses and the time course profiles of each pesticide were well fitted into the first order dechlorination reaction. The optimum observed rate constant (k_obs’) values for endosulfan (0.2168, 0.1209 and 0.1614 min⁻¹ for 10, 30 and 50 ppm initial concentration respectively) and lindane (0.1746, 0.1968 and 0.2253 min⁻¹ for 10, 30 and 50 ppm initial concentration respectively) dechlorination were obtained when the reactions were conducted with doses of 7.5/1 mg ml⁻¹ and 5/1 mg ml⁻¹ Mg⁰/ZnCl₂ respectively. Endosulfan and lindane were completely dechlorinated into their hydrocarbon skeletons namely, Bicyclo [2,2,1] hepta 2-5 diene and Benzene respectively as revealed by GCMS analysis.     

Effect of different side chains on alternating copolymers of benzodithiophene and thiophene in organic solar cells

Polymeric semiconductors offer the dual advantages of lightness and flexibility, facilitating the large-scale production of organic electronic devices. In the present research, electron donor polymers were synthesized incorporating high electron density aromatic units, specifically benzodithiophene (BDT) and thiophene (Th), to explore their efficacy in organic electronics. This systematic study focused on evaluating the impact of varying side chains on the material properties of these polymers. It was found that polymers with Th side chains exhibited significantly enhanced thermal stability, approximately 100°C higher than their alkoxide side chain counterparts. For the polymer PEHO-BDT3HT, a bandgap value of around 1.6 eV was obtained. Furthermore, binary devices were developed using these novel copolymers, among which PDT-BDT3HT demonstrated superior photovoltaic performance, achieving a power conversion efficiency of 1.56% without any optimization. This work not only sheds light on the influence of side chain variations in polymer properties but also showcases the potential of BDT and Th-based copolymers in the field of organic electronics.     

A review of diseases associated with household air pollution due to the use of biomass fuels

Nearly one third of the world's population use biomass fuels such as coal, wood, animal dung, and crop residues as their primary source of domestic energy. Due to their incomplete combustion, a multitude of pollutants associated with high levels of indoor air pollution (IAP) are released which include suspended particulate matter (SPM), carbon monoxide, formaldehyde, nitrogen dioxide, polycyclic aromatic hydrocarbons (PAH), etc. There is a line of evidence that exposure to those pollutants can lead to increased risk of diseases including respiratory infections (e.g., pneumonia, tuberculosis and chronic obstructive pulmonary disease (COPD), lung cancer, and asthma), low birth weight, cataracts, and cardiovascular events. It is one of the major global public health threats that require greater efforts for prevention through research and policy-making. This review summarizes the available information on potential health risks associated with biomass fuel use.     

Morphology of the stifle in agouti (Dasyprocta prymnolopha,Wagler 1831)

The agouti (Dasyprocta prymnolopha, Wagler 1831) is a wild rodent of great zootechnical potential, a fact that enables anatomical and morphological studies to support management actions with this animal. In this perspective, this study aimed to describe the anatomy and histology of the agouti stifle joint. Four adult agoutis were used, two females and two males. The animals were submitted to dissection and identification of the structures of the stifle joint. For light microscopy study, samples of the patellar ligament, cranial and caudal cruciate ligaments, medial and lateral collateral ligaments were used. Agouti has a highly congruent patellofemoral joint; elongated patella; medial and lateral fabellae at the proximal insertion of the gastrocnemius muscle; medial and lateral meniscus with lunula; in addition to the presence of the following ligament structures: patellar ligament, cranial and caudal cruciate ligaments, medial and lateral collateral ligaments, meniscofemoral ligament, caudal meniscal ligament of the medial meniscus, and medial and lateral cranial ligaments. The patellar ligament presents bundles of parallel collagen fibers with a straight path and coated fibroblasts; collateral and cruciate ligaments had loose and dense connective tissue, coated fibroblasts and collagen bundle undulations, the latter most expressive in the caudal cruciate ligament. Thus, except for the shape and angulation of the stifle, which allows specific movements, the agouti stifle has structures analogous to that of other rodents and domestic animals.     

Untersuchungen an Kaffee und Kaffee-Ersatz

Zusammenfassung Der Gehalt an einem mit alkalischer Kupferlösung fällbaren Galaktomannan nahm in Kaffee-Extrakten, die mit steigender Ausbeute aus einemColumbia arabica-Kaffee gewonnen worden waren, bis zu einer Extraktausbeute von 43,6% langsam, bei noch stärkerer Extraction jedoch etwas rascher ab. EinAngola robusta-Kaffee verhielt sich entgegengesetzt. Hier nahm die Galaktomannan-Menge mit der Extraktausbeute laufend zu, wenn auch nicht gleichmäßig. Berechnet auf den Röstkaffee lieferte dieArabica-Sorte eine ziemlich eng begrenzte Menge an fällbarem Polysaccharid, dieRobusta-Probe gab jedoch zunehmend Galaktomannan ab. Das unterschiedliche Verhalten der beidenCoffea-Arten wird auf eine mehr oder weniger starke Bindung dieses hochpolymeren Kohlenhydrat-Anteils in der Zellwand zurückgeführt.

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Studies on coffee and coffee substitutesXIX. Dependence of the quantity of a highly polymeric galactomannan on the degree of extraction of coffee-extracts

Summary In extracts ofColumbia Arabica Coffee the content of galactomannan precipitable with alcaline copper solution decreases slowly up to an extraction yield of 43.6%; it decreases somewhat more rapidly with higher extraction yields. An extract ofAngola Robusta Coffee showed opposite behaviour. In this case the content of galactomannan increased with the extraction yield, although not evenly. Calculated on the basis of roasted coffee solids the extract of theArabica coffee had a rather limited range precipitable polysaccharide, theRobusta coffee in contrast with rated increased amounts of galactomannan. The different behaviour of the two coffee varieties may be due to more or less strong binding of this high-polymer carbohydrate to the cell wall.

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XVIII. Mitt.: V. Ara u. H. Thaler: Z. Lebensm. Unters.-Forsch.161, 143 (1976)

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Auszug aus der Dissertation V. Ara: Zur Kenntnis eines mit alkalischer Kupferlösung fällbaren Galaktomannans in Kaffee-Extrakten. Techn. Universität Braunschweig, 1973. Der Deutschen Forschungsgemeinschaft sei auch an dieser Stelle für die Unterstützung der Arbeit gedankt     

Determination of Phthalate Residues in Different Types of Yogurt by Gas Chromatography-Mass Spectrometry and Estimation of Yogurt-Related Intake of Phthalates

Phthalates are potential endocrine-disrupting chemicals, found widely in the environment, and commonly used to make plastics softer and more flexible. Little information is available about the presence of phthalates in yogurt products sold on the world market. This study aimed to develop a sensitive GC-MS method for the determination of selected phthalates in yogurt and residue levels in fruit yogurts together with the packaging materials and to estimate a yogurt-related exposure to phthalates in the Turkish population. Acetonitrile extraction followed by cleanup procedures using different adsorbents yielded relatively clean extracts. The presence as the percent of selected phthalates tested—dibutyl phthalate (DBP), diethylhexyl phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-octyl phthalate (DNOP), and benzyl butyl phthalate (BBP)—were determined as 76, 70, 70, 54, 20, and 8% of the samples, respectively, for the phthalates, ranging from <LOQ to 1640 μg/kg. The highest concentrations were found in cherry yogurt among the fruit yogurts, while banana and pineapple yogurts contained the least. The results indicate that the estimated daily intakes for phthalates were below tolerable daily intakes.     

Analysis of mixed convection in an inclined square cavity using nanofluids with Vajjha and Das' nanofluid model

In this article, the effects of angle of inclination on heat transfer by mixed convection have been analyzed numerically in a square cavity packed with a CuO nanofluid. Cavity boundaries are constructed by having sinusoidal varying temperature on sidewalls, inactive horizontal walls, and the hot passing plate at the center of the cavity. The transport equations for fluid and heat are solved using the finite-volume method with SIMPLE algorithm. The Richardson number (Ri) varying from 0.01 to 100, inclination angle (γ) from 0° to 90°, wall speed ratios (λ) from 0 to 3 and volume fraction of nanoparticles (φ) from 0.0 to 0.1 are given and represented in the form of flow fields, temperature fields, and mean heat transfer graphs. It is detected that the principal flow constraints have a substantial impact on the flow lines and thermal lines. Specifically, the structures of cavity inclination, existence of copper nanoparticles, and the hot wall in motion at the midpoint of the cavity are established to enrich the overall rate of heat transfer. Correspondingly, in the present study, the Vajjha and Das model is taken into account for the effective thermal conductivity and viscosity of the nanofluid; application of this model is beneficial for the industries working in a high-temperature environment.