Camphor Vapour Research Articles

Synthesis and characterization of hierarchical suspended carbon fiber structures decorated with carbon nanotubes

Carbon nanotubes (CNTs) and carbon microfibers (CMFs) have received significant attention due to their exceptional mechanical and electrical properties, which make them promising materials for various applications. This study introduces a novel approach to integrate CNTs and CMFs into a unified architecture by simultaneously conducting pyrolysis and chemical vapor deposition (CVD). The localized CVD of CNTs on suspended CMFs was achieved by utilizing Fe–Co nanoparticles (NPs) embedded in polyacrylonitrile (PAN) fibers as catalysts. Scanning electron microscopy and elemental analysis confirmed the formation of needle-like carbon structures on the pyrolyzed fiber surface, where carbon gases released from the pyrolyzing PAN fiber acted as the carbon source for the localized CVD. The incorporation of an additional carbon source, such as camphor vapor, significantly enhanced the growth and density of CNTs on the CMF. Various characterization techniques, including transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and Atomic Force Microscopy, were employed to analyse the properties of the synthesized materials. The substantial increase in electrical conductivity upon incorporating CNTs highlights their positive influence on electrical properties and defect reduction. These characterization results highlight the potential applications of the fabricated structures in various fields, including sensors, lithium-ion electrodes, and microfabrication. In addition, the economic advantages of optimizing the process by integrating CVD with pyrolysis were assessed, revealing decreased operation time, lower energy consumption, and reduced chemical costs in comparison to conventional methods involving multiple intermediate processing steps.Graphical

The toxic effect of camphor vapour against Aphis craccivora Koch (Hemiptera: Aphididae) and some of its natural enemies

Fumigant toxicity of camphor was studied against the aphid Aphis craccivora Koch and three associated natural enemies, i.e. Coccinella undecimpunctata L., Aphelinus albipodus Hayat & Fatima and Aphidius colemani Viereck. Aphis craccivora was the most tolerant one compared with all tested natural enemies as the recorded LC50 values were 12.71, 6.33, 1.16 and 0.48 mg camphor/liter space for the above mentioned insects, respectively. Subjecting newly emerged adults of A. craccivora to LC25 of camphor vapor significantly reduced female longevity from 17.6 to 6.45 days and reduced the female daily progeny from 4.44 to 1.93 nymph / female, which resulted in a reduction in productivity as finite rate of increase decreased from 1.57 to 1.14 female / female / day. Aphids that survived after subjection to LC50 were found to have significantly higher amount of acid phosphatase and G. S-transferase than non-treated aphids. Inversely, Survived aphids were found to have significantly less amount of β-esterases and alkaline phosphatase than nontreated aphids; while no significant difference was found in case of α-esterases. Camphor fumigant can be a candidate as a control agent against A. craccivora but with restriction because of its drawbacks on natural enemies.

Fumigant Toxicity of camphor Against Tetranychas urticae Koch and Two Phytoseid Predators (Tetranychidae: phytoseiidae)

In attempt to find a new fumigant acaricide could be used in green houses fumigant toxicity of camphor was studied against Tetranychus urticae Koch and two predators i.e. Neoseiulus californicus (Mc.Gr.) and Phytoseiulus persimilis A.-H. Camphor vapor gave a reasonable toxicity. Increasing temperature resulted in increasing toxicity as raise of temperature from 20 to 35°C decreased LC50 values from 3.28 to 2.61 mg/L and from 7.13 to 2.76 mg/L in case values 3.48 and 3.97 mg/L under 25°C, respectively. Subjecting protonymphs to LC50 for 24h resulted in significant shortage in the oviposition period and reduction in egg number reflecting reduction in finite rate of increase from 1.349 (non-treated mites) to 1.239 female/ female/day.

A new thermal desorption solid-phase microextraction system for hand-held ion mobility spectrometry

In this paper a new prototype of solid phase microextraction–ion mobility spectrometry (SPME–IMS) system was developed to effectively couple the extraction efficiency of SPME with the detection capability of IMS. The main component of this system was the transfer line/desorber, which was a low-thermal-mass (ca. 0.15 g) silicosteel coatings stainless steel tube. The transfer line/desorber was designed to rapidly desorb and transfer the analytes extracted by SPME to IMS. A custom-made temperature controller with a proportional–integral–differential (PID) was used to maintain the temperature of the transfer line/desorber stable and avoid overheating or oscillating. The low thermal mass of this interface allowed it to be rapidly heated and cooled with much less electrical power and could substantially reduce the demand for high capacity batteries. The operational characteristics of this system were demonstrated through the analysis of camphor vapour. The precision of reduced mobility and the peak amplitude of camphor were good (R.S.D. 0.62%, n = 10; R.S.D. 2.5%, n = 10, respectively). SPME–IMS system was also shown to be capable of on-site measurement by monitoring the biogenic volatile organic compounds (BVOCs) emitted from eucalyptus citriodora leaves. In addition, this system was applied to quantitation of diazepam and cocaine in aqueous solution. Limits of detection were 10 ng/mL for diazepam and 50 ng/mL for cocaine with the reported experimental conditions. This SPME–IMS system exhibits considerable promise as a robust, simple, rapid, energy-saving fieldable approach for on-site analysis of analytes in various matrix.

Controlling the diameter distribution of carbon nanotubes grown from camphor on a zeolite support

Single-wall and multi-wall carbon nanotubes (SWNTs and MWNTs, respectively) of controlled diameter distribution were selectively grown by thermal decomposition of a botanical hydrocarbon, camphor, on a high-silica zeolite support impregnated with Fe–Co catalyst. Effects of catalyst concentration, growth temperature and camphor vapor pressure were investigated in wide ranges, and diameter distribution statistics of as-grown nanotubes was analyzed. High yields of metal-free MWNTs of fairly uniform diameter (∼10 nm) were grown at 600–700 °C, whereas significant amounts (∼30%) of SWNTs were formed at 850–900 °C within a narrow diameter range of 0.86–1.23 nm. Transmission electron microscopy and micro-Raman spectroscopy reveal that camphor-grown nanotubes are highly graphitized as compared to those grown from conventional CNT precursors used in chemical vapor deposition.

Camphor-based carbon nanotubes as an anode in lithium secondary batteries

Camphor vapour is pyrolysed in the presence of Fe, Ni and Co powder under a dinitrogen atmosphere at different temperatures (750–1050 °C). While Fe and Ni catalyse the formation of carbon nanotubes (CNs), Co facilitates carbon nanobead growth. The CNs, obtained using a Fe catalyst at 950 °C, are utilised as the anode in Li secondary batteries. The capacity of the batteries constructed in this way is as good as those prepared by graphitic carbon formed in the arc process.

Nano-range octopus type vapor grown carbon fibers from camphor

Carbon nanofibers are synthesised by pyrolysis of camphor vapor in nitrogen atmosphere in the temperature range of 650°C to 750°C. Thickness of carbon fibers increases from 30 nm to 250 nm with an increase of pyrolysis temperature. Characterizations of these fibers were done by SEM and TEM. A novel growth of carbon nanofibers of octopus type has been seen on the electrochemically nickel-plated copper sheet. At higher magnification of TEM studies, carbon nanofibers are found to made up of many thin cotton threads like structures.

NANO-RANGE OCTOPUS TYPE VAPOR GROWN CARBON FIBERS FROM CAMPHOR

Carbon nanofibers are synthesised by pyrolysis of camphor vapor in nitrogen atmosphere in the temperature range of 650°C to 750°C. Thickness of carbon fibers increases from 30 nm to 250 nm with an increase of pyrolysis temperature. Characterizations of these fibers were done by SEM and TEM. A novel growth of carbon nanofibers of octopus type has been seen on the electrochemically nickel-plated copper sheet. At higher magnification of TEM studies, carbon nanofibers are found to made up of many thin cotton threads like structures.

Effect of pyrolyzing time and temperature on the bandgap of camphor-pyrolyzed semiconducting carbon films

Intrinsic p- and n-type semiconducting carbon thin films have been synthesized by the pyrolysis of camphor vapor in an argon atmosphere at various temperatures for different periods of time. These films are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) analyses, Hall measurement and electrical conductivity studies. The nature of conductivity of camphor-pyrolyzed semiconductors is found to be extremely sensitive to the pyrolyzing temperature and time. It is observed that an sp 2 content in the as-grown film of less than 33% yields a p-type semiconductor, whereas more than 33% sp 2 makes it n-type. The percentage contents of sp 2 and sp 3 carbon can be controlled by the temperature and time of pyrolysis.

Spongy carbon nanobeads—A new material

Spherical carbon nanobeads (solid and hollow) of two sizes of around 500–850 nm (large) and 250 nm (small) were synthesized by pyrolysing camphor vapour at 1000 °C in an argon atmosphere, using ferrocene, as catalyst, for the first time. The EEL spectrum suggests the carbon beads to be non-graphitic and these are covered by a graphitic shell of 80–100 nm, revealed by transmission electron microscopy (TEM) micrographs. The larger beads, more than 10 are interconnected by the outer shell. After covering the train of carbon, the beads take the shape of fibrous graphitic carbon which perhaps gives the spongy elastic character to the material. The average surface area of the nanobeads determined by BET studies is calculated to be 16 m 2g −1. It is suggested that this material may be a useful anode for secondary lithium ion batteries.

Failure to observe electron circular dichroism in camphor

Analogous to optical circular dichroism, it is possible to have electron circular dichroism, the preferential transmission of longitudinally polarized electrons through a chiral medium. Using stereoisomers of camphor vapor as a scattering target, we looked for this effect at incident electron energies of 1, 3, 5, 7, or 10 eV. Within our detection limit (~0.02%) we have not observed a spin-dependent asymmetric transmission.

Electron scattering from chiral molecules

Detailed information is given on an experiment which was carried out to investigate the spin-dependent attenuation of electron beams transmitted through a vapour of chiral molecules. The experiment is considered to be the first verification of electron dichroism. A transmission asymmetry for longitudinally polarized electron beams of opposite helicity was observed for , a camphor-like molecule containing an ytterbium atom, and also recently for bromocamphor. Asymmetries of about , which is clearly above the detection limit, were measured for both targets at electron energies between 0.5 and 10 eV. No asymmetry was found when enantiomeric camphor vapour was used as the target, thus contradicting a result which has been previously published by another group. The asymmetry measurements are compared with electron transmission spectra, which show that the energies where resonant temporary-ion formation takes place and those of the extrema of the asymmetry agree to a great extent.

Age-related regulation of mouse brain cortex adrenoceptors following camphor vapor exposition

The paper deals with the ability of adrenergic receptors (AR) of mouse brain cortex to be differentially regulated in response to single or multiple expositions to camphor vapor. The regulation of alpha- and beta-adrenoceptors has been studied in young and old Balb/c-nu mice. Results confirm the decrease of total beta-adrenoceptor density previously observed in untreated mice with advancing age; in addition, receptor density decreases in both young and old mice after a single exposition to camphor vapor, followed by an adaptation after multiple stimuli. The beta1, subtype is mainly responsible for density decrease in young animals, while both beta1, and beta2 subtypes contribute to the decrease in old mice. On the contrary, beta2 subpopulation gives the major contribution to the adaptive recovery in both young and old mice. alpha-Adrenoceptors also show an age-related decrease in the control group; after a single exposition they show an increased density with the exception of alpha1-subset in the young group. Repeated expositions lead to a rather general adaptive response towards pre-stimuli conditions. The differential behaviour of receptor subtypes in response to camphor vapor exposition can be related to the differential alterations of receptor characteristics observed during aging and also suggests a possible mechanism through which these alterations may occur.

Experimental verification of electron optic dichroism.

Electron optic dichroism, i.e., the spin-dependent attenuation of electron beams transmitted through the vapor of chiral molecules, was investigated. No transmission asymmetry was found for longitudinally polarized electron beams of opposite helicity passing through enantiomeric camphor vapor. The experiment was carried out at electron energies of 0.9, 4.0, and 5.0 eV with an accuracy much better than ${10}^{\ensuremath{-}4}$. Asymmetries up to $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, which was clearly above the detection limit, were, however, observed for Yb(hfc${)}_{3}$, a camphorlike molecule containing an ytterbium atom.

Effect of Camphor Vapour and Temperature on the Frequency of Aberrant Asci in Sordaria

ALTHOUGH the occurrence of asci containing 6 : 2, 5 : 3 and 7 : 1, rather than 4 : 4 spore ratios, is now widely recognized in Ascomycetes, little is known about environmental effects on their frequency. In these experiments the effects of temperature and camphor vapour were analysed. The latter substance was chosen because it is known to increase the frequency of diploidization in vegetative hyphae1, and it would therefore be expected to increase the frequency of aberrant tetrads if the latter are related to mitotic recombination2.

Induction of 'Gigas' Forms of Penicillium Notatum by Treatment with Camphor Vapour

CAMPHOR has been reported by Bauch1 to be effective in inducing polyploidy in fungi. Thaysen and Morris2 succeeded in producing a giant strain of Torulopsis utilis by treatment with camphor vapour. It was therefore determined to test the effect of camphor vapour on Penicillium notatum strain N. R. R. L. 1978 B. The procedure was to add different, amounts of camphor to flasks each containing 25 ml. of sterilized 3 percent malt agar. The agar was then poured into Petri dishes of 100 mm. diameter. The cultures on the plates to which 75 mgm. of camphor had been added showed a distorted growth. Conidial formation was delayed but after twenty-two days some spores were formed. When these were examined microscopically, some of the spores were found to be larger than the others, whereas spores from control cultures were uniform in size. Spores from the treated and control cultures were plated out on malt agar by the dilution method. There were no macroscopic differences between the colonies from the control and treated samples. When examined for spore size, however, thirty colonies from the control series were found to have spores of the same size, whereas, out- of forty-four colonies from the treated samples, thirty-five were like the controls, five had spores larger than the controls and four had a mixture of large and average sized spores. Isolations were made from these large-spored colonies and 'gigas' lines established. Fig. a shows spores from a normal line and Fig. b spores from a gigas line, three months after isolation and after being subcultured four times. The change thus appears to be permanent. Camphor treatment has been shown to induce polyploidy in higher plants3, and since pollen grain size has been found to be a useful criterion of polyploidy, it is probable that the 'gigas' forms with larger spores in Penicillium are polyploids.

Societies and Academies

LONDON. Royal Society, Jan. 28.—T. M. Lowry and H. K. Gore: Optical rotatory power of vapours. The optical rotations of the vapours of camphor and of camphor quinone are (M)5893 = 83° at 180° C., and - 146° at 200°, respectively. The curve of rotatory dispersion of camphor vapour shows a sharp maximum (α)180°=2000° at 3200 A., followed by a reversal of sign at 3020 A., and a negative maximum (α)180° = - 18600 at 2800 A. A ‘step-out’ on the short wavelength side of the positive maximum is in harmony with the fact that the curve of circular dichroism of a solution of camphor in hexane extends over only a part of the absorption band, on the side of longer wave-lengths. A solution of camphor in cyclohexane shows a positive maximum (α)20°=2600° at 3200 A., followed by a step-out, a reversal of sign, and a negative maximum (α)20° =2100° at about 2720 A. The curve of rotatory dispersion of camphor quinone passes through a negative maximum (α)200° = - 500° at 4950 A. for the vapour and (α)20° = -450° at 4940 A. in cyclohexane, followed by a reversal of sign at 4740 A. and a positive maximum (α)= +300° at 4440 A.—H. W. B. Skinner: The excitation potentials of light metals (1). Lithium. There are critical potentials and also, apparently, some bands of radiation in the voltage region less than 20 volts. These must be associated with the conduction electron system. But the more important aspect of the work is concerned with the emission of the K -radiation of lithium metal. The radiation was found to consist of a band with a maximum frequency corresponding to 54 volts. It is shown that the ionisation of the K-shell alters the levels in the metal in such a way that there are empty levels around the ionised atom into which the K-electron can switch.—E. G. Cox: The crystalline structure of benzene. By consideration of the intensities of the X-ray reflections from a number of lattice-planes it has been found possible to decide on the arrangement of the molecules in the lattice, and in addition it is found that the experimental results are strongly in favour of a flat-ring molecule.