There is considerable interest from a regulatory and public health perspective in harmful and potentially harmful constituents in tobacco products, including smokeless tobacco products (STPs). A wide range of commercial STPs from the US and Sweden, representing 80–90 % of the 2010 market share for all the major STP categories in these two countries, were analysed for the IARC Group 2A carcinogen acrylamide. These STPs comprised the following styles: Swedish loose and portion snus, US snus, chewing tobacco, moist snuff, dry snuff, soft pellet, hard pellet and plug.
Results
Acrylamide was detected in all the products tested and quantified in all but one product. Concentrations ranged from 62 to 666 ng/g wet weight basis (WWB). The average levels of acrylamide (WWB) by type of STP were not significantly different (p > 0.05) except for US snus which had, on average, greater levels but with a very wide range of individual levels according to the manufacturer. Acrylamide levels in STPs were significantly and positively correlated with pH, but not with levels of either reducing sugars or ammonia nitrogen. Levels of acrylamide increased by sixfold or more (on a dry weight basis) during manufacture of a snus sample and then decreased during subsequent storage for up to 22 weeks. Acrylamide generation in tobacco generally appears to occur at lower temperatures, but longer time scales than found with food production.
Conclusions
Acrylamide is a common contaminant of STPs, formed through heat treatment of tobacco. Our data show that exposure to acrylamide from consumption of STPs is small compared with exposure from food consumption or cigarette smoking.
Sulfoxides are reduced by a combination of sodium borohydride, a catalytic amount of cobalt(II) chloride hexahydrate, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane to produce the corresponding sulfides in good to excellent yields under mild conditions. An interesting structural influence of sulfoxides on their reactivity is observed.
The authors thank Dr. Akira Yoshida (Tokyo City University, Instrumental Analysis Center) for his help in carrying out the SEM experiment. The authors also thank Tae Tokuhata for helpful discussions. 相似文献
Green approach in synthesizing metal nanoparticles has gain new interest from the researchers as metal nanoparticles were widely applied in medical equipment and household products. The use of plants in the synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. A green synthetic route for the production of stable silver nanoparticles (Ag-NPs) by using aqueous silver nitrate as metal precursor and Artocarpus elasticus stem bark extract act both as reductant and stabilizer is being reported for the first time.
Results
The resultant Ag-NPs were characterized by UV–vis spectroscopy, powder X-Ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infra-red (FT-IR). The morphological study by TEM and SEM shows resultant Ag-NPs in spherical form with an average size of 5.81 ± 3.80, 6.95 ± 5.50, 12.39 ± 9.51, and 19.74 ± 9.70 nm at 3, 6, 24, and 48 h. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The FT-IR spectrum shows prominent peaks appeared corresponds to different functional groups involved in synthesizing Ag-NPs.
Conclusions
Ag-NPs were synthesized using a simple and biosynthetic method by using methanolic extract of A. elasticus under room temperature, at different reaction time. The diameters of the biosynthesis Ag-NPs depended on the time of reaction. Thus, with the increase of reaction time in the room temperature the size of Ag-NPs increases. From the results obtained in this effort, one can affirm that A. elasticus can play an important role in the bioreduction and stabilization of silver ions to Ag-NPs.
Abstract 10-Hydroxycamptothecin is prepared by chemoselective catalytic hydrogenation of the B-ring of camptothecin over PtO2 with sulfur moderators followed by oxidation using iodobenzenediacetate. New moderators (viz. thioanisole, dimethyl sulfide, diphenyl sulfide, 2-mercapto ethanol), which moderate the hydrogenation of the B- ring of camptothecin, are being explored.
The authors thank the management of Dr. Reddy's Laboratories Ltd. for supporting this work, and support from analytical colleagues is highly appreciated. 相似文献
The diluted aerosols from a cigarette (3R4F) and an e-cigarette (Vype ePen) were compared in two commercially available in vitro exposure systems: the Borgwaldt RM20S and Vitrocell VC10. Dosimetry was assessed by measuring deposited aerosol mass in the exposure chambers via quartz crystal microbalances, followed by quantification of deposited nicotine on their surface. The two exposure systems were shown to generate the same aerosols (pre-dilution) within analytically quantified nicotine concentration levels (p = 0.105). The dosimetry methods employed enabled assessment of the diluted aerosol at the exposure interface. At a common dilution, the per puff e-cigarette aerosol deposited mass was greater than cigarette smoke. At four dilutions, the RM20S produced deposited mass ranging 0.1–0.5 µg/cm2/puff for cigarette and 0.1–0.9 µg/cm2/puff for e-cigarette; the VC10 ranged 0.4–2.1 µg/cm2/puff for cigarette and 0.3–3.3 µg/cm2/puff for e-cigarette. In contrast nicotine delivery was much greater from the cigarette than from the e-cigarette at a common dilution, but consistent with the differing nicotine percentages in the respective aerosols. On the RM20S, nicotine ranged 2.5–16.8 ng/cm2/puff for the cigarette and 1.2–5.6 ng/cm2/puff for the e-cigarette. On the VC10, nicotine concentration ranged 10.0–93.9 ng/cm2/puff for the cigarette and 4.0–12.3 ng/cm2/puff for the e-cigarette. The deposited aerosol from a conventional cigarette and an e-cigarette in vitro are compositionally different; this emphasises the importance of understanding and characterising different product aerosols using dosimetry tools. This will enable easier extrapolation and comparison of pre-clinical data and consumer use studies, to help further explore the reduced risk potential of next generation nicotine products.
Graphical abstract A cigarette and an e-cigarette (top left) were assessed on two different in vitro exposure systems, the Borgwaldt RM20S (top right) and the VC 10 (bottom right). Compositionally the product aerosols were different, but there was no difference between the same product on different machines (bottom left).
The extracts from the aerial parts of Portulaca quadrifida have been reported to show the total flavonoid content, antioxidant and antibacterial activities.
Results
Our results revealed that the total flavonoid content of methanol and chloroform extracts is 2.335?±?0.0097 and 1.7312?±?0.0082 mgQE/100 g respectively. The two extracts also showed good antioxidant activity and total phenolic content as well as weak to moderate antibacterial activity against some bacteria.
Conclusions
The extracts the aerial parts of the P. quadrifida showed good total flavonoid content, DPPH radical scavenging activity and antibacterial activity. In addition to this, the extracts also showed the presence of some important compounds by phytochemical analysis.
A photoelectrochemical wire microelectrode was constructed based on the use of a TiO2 nanotube array with electrochemically deposited CdSe semiconductor. A strongly amplified photocurrent is generated on the sensor surface. The microsensor has a response in the 0.05–20 μM dopamine (DA) concentration range and a 16.7 μM detection limit at a signal-to-noise ratio of 3. Sensitivity, recovery and reproducibility of the sensor were validated by detecting DA in spiked human urine, and satisfactory results were obtained.
Graphical abstract Schematic of a sensitive photoelectrochemical microsensor based on CdSe modified TiO2 nanotube array. The photoelectrochemical microsensor was successfully applied to the determination of dopamine in urine samples.
The authors gratefully acknowledge financial support from the Covenant College Kaleo Center. In addition, we are indebted to the W. R. Grace Company, Chattanooga, for the generous donation of Raney nickel catalyst. 相似文献
In this paper and for the first time in the literature, we introduce a new three-stages symmetric six-step finite difference pair with optimal phase and stability properties. The basic characteristics of the new finite difference pair are:
1.
Is a symmetric hybrid six-step method,
2.
Is of three stages
3.
Is of twelfth algebraic order,
4.
Has vanished the phase-lag,
5.
Has vanished the derivatives of the phase-lag up to order four.
For this new finite difference pair we present a detailed analysis which consists of the following:
1.
The development of the new three-stages symmetric six-step finite difference pair
2.
The presentation of the local truncation error of the new finite difference pair
3.
A comparative error analysis of the new finite difference pair with other finite difference pairs of the same family: the the classical finite difference pair of the family (i.e. the finite difference pair with constant coefficients), the recently developed finite difference pairs of the same family with vanished phase-lag and its first derivative, the recently developed scheme of the same family with vanished phase-lag and its first and second derivatives and finally with the recently developed finite difference algorithm of the same family with vanished phase-lag and its first, second and third derivatives .
4.
A stability and an interval of periodicity analysis and
5.
Finally, the evaluation of the accuracy and computational efficiency of the new three-stages symmetric six-step finite difference pair for the solution of the Schrödinger equation.
The theoretical and numerical analysis of the produced new three-stages symmetric six-step finite difference pair, which are presented in this paper, show the effectiveness of the new scheme compared with other known or recently developed algorithms of the literature.
Thin films of La2O3 were deposited onto glass substrates by ultrasonic spray pyrolysis. Their structural and morphological properties were characterized by X-ray diffraction, Fourier transform Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photo-electron spectroscopy, Brunauer-Emmett-Teller and optical absorption techniques. The sensor displays superior CO2 gas sensing performance at a low operating temperature of 498 K. The signal change on exposure to 300 ppm of CO2 is about 75%, and the signal only drops to 91% after 30 days of operation.
Graphical abstract Schematic diagram of the CO2 gas sensing mechanism of an interconnected web-like La2O3 nanostructure in presence of 300 ppm of CO2 gas and at an operating temperature of 498 K.
Abstract A simple and efficient method for multicomponant synthesis of 3,4-dihydropyrimidinones has been reported. All the reactions were carried out using samarium triflate as catalyst (10 mol%) at acetonitrile reflux. This procedure is applicable to a variety of substrates such as aliphatic, aromatic, and heterocyclic aldehydes.
A collision induced dissociation (CID) structure for lossless ion manipulations (SLIM) module is introduced and coupled to a quadrupole time-of-flight (QTOF) mass spectrometer. The SLIM CID module was mounted after an ion mobility (IM) drift tube to enable IM/CID/MS studies. The efficiency of CID was studied by using the model peptide leucine enkephalin. CID efficiencies (62%) compared favorably with other beam-type CID methods. Additionally, the SLIM CID module was used to fragment a mixture of nine peptides after IM separation. This work also represents the first application of SLIM in the 0.3 to 0.5 Torr pressure regime, an order of magnitude lower in pressure than previously studied.
A new synthesis of 3-methoxypropanal from glycerol was presented. With this new approach, the conversion of glycerol to 3-methoxypropanal can be effected in moderate yield using catalysts of copper sulfate and polyethylene glycol (PEG).
In this paper, we build, for the first time in the literature, a new four-stages symmetric six-step finite difference pair with optimized properties. The method:
1.
is a symmetric non-linear six-step method,
2.
is of four stages
3.
is of fourteenth algebraic order,
4.
has eliminated the phase-lag,
5.
has eliminated the first and second derivatives of the phase-lag.
An analysis of the new proposed method is given in details in this paper. More specifically, we present:
1.
the building of the new four-stages symmetric six-step method,
2.
the computation of the local truncation error of the new proposed method,
3.
the comparative local truncation error analysis of the new proposed method with other finite difference pairs of the same family.
4.
the stability and the interval of periodicity analysis and
5.
finally, the investigation and evaluation of the computational efficiency of the new proposed scheme for the approximate solution of the Schrödinger equation.
The theoretical, computational and numerical results for the new proposed method show its effectiveness compared with other known or recently obtained finite difference pairs in the literature.
In a short reaction time, acyl chlorides and dry tetrahydrofuran react in the presence of a catalytic amount of magnesium turnings (Mg) at 25 °C to give 4-chlorobutyl esters in excellent yields.
Tetrahydroimidazolpyridinones 2, which are new, highly bioactive potential insecticides, were prepared in 30–96% yield through a multicomponent reaction (MCR) of 6-Cl-PMNI, aldehydes, and Meldrum's acid using catalytic Et3N or K2CO3 in anhydrous CH3CN at refluxing temperature.
This work was financially supported by the Shanghai Committee of Science and Technology (No. 064319022), the New Century Excellent Talents in University, the Ministry of Education, China (No. NCET-07-0283), the Natural Science Foundation of China (No. NSFC 20602011), and the “111” Project (No. B07023). 相似文献
