Mechanistic Studies on the Photooxidation of Commercial Polybutadiene

1975 ◽  
Vol 48 (4) ◽  
pp. 692-704 ◽  
Author(s):  
S. W. Beavan ◽  
D. Phillips
Keyword(s):  
Polymer Degradation ◽  
Analytical Techniques ◽  
Ultraviolet Spectroscopy ◽  
Gas Liquid Chromatography ◽  
Mechanistic Studies ◽  
Oxidative Polymer ◽  
Unsaturated Carbonyls ◽  
Phosphorescence Emission ◽  
Plausible Mechanism ◽  
Physical And Chemical

Abstract Products from both the thermal and photooxidation of polybutadiene have been studied using various analytical techniques such as infrared and ultraviolet spectroscopy, gas—liquid chromatography, phosphorescence emission, and phosphorescence excitation spectroscopy. Analyses have allowed a plausible mechanism to be formulated for the photooxidation of this polymer, consistent with all the observed physical and chemical changes. Both photo- and thermal oxidative polymer degradation initially result in the formation of α,β-unsaturated carbonyls which, under photo-degrading conditions, are subsequently photolysed to yield the observed final products.

scholarly journals In Vitro Comparison of Bioactive Silicon Nitride Laser Claddings on Different Substrates

2020 ◽  
Vol 10 (24) ◽  
pp. 9039
Author(s):  
Elia Marin ◽  
Matteo Zanocco ◽  
Francesco Boschetto ◽  
Toshiro Yamamoto ◽  
Narisato Kanamura ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Nitrogen Loss ◽  
Antibacterial Properties ◽  
Analytical Techniques ◽  
Osteosarcoma Cell ◽  
Treatment Conditions ◽  
Substrate Properties ◽  
Coated Surface ◽  
Physical And Chemical

The performance, durability, and bio-integration of functional biomedical coatings can be enhanced by changing or improving their substrate properties. In this study, we applied silicon nitride powder-based laser claddings to various substrates and undertook an in vitro assessment of their osteoconductive and antibacterial properties. The substrates included common arthroplasty materials: polyethylene, titanium, zirconia-toughened alumina, and zirconia. Multiple analytical techniques were used to characterize the physical and chemical structure of the claddings after deposition. Partial decomposition of the silicon nitride powders occurred during the cladding process, resulting in nitrogen loss during intermetallic formation phases under some substrate and treatment conditions. The osteoconductive capabilities of various laser-cladded substrates were evaluated in a SaOS-2 osteosarcoma cell culture by measuring the amount of bone formation on the coated surface. Antibacterial testing was performed using Gram-positive Staphylococcus epidermidis at 24 and 48 h of incubation. Silicon nitride coating enhanced both osteoconductive and antibacterial properties.

Mechanistic studies of base-catalysed lignin depolymerisation in dimethyl carbonate

2018 ◽  
Vol 20 (1) ◽  
pp. 170-182 ◽  
Author(s):  
Saumya Dabral ◽  
Julien Engel ◽  
Jakob Mottweiler ◽  
Stephanie S. M. Spoehrle ◽  
Ciaran W. Lahive ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Lignin Degradation ◽  
Dimethyl Carbonate ◽  
Analytical Techniques ◽  
Mechanistic Studies

Various analytical techniques and DFT calculations have been applied in studying base-catalysed lignin degradation in dimethyl carbonate.

Compatibility and Stability of Paclitaxel Combined with Cisplatin and with Carboplatin in Infusion Solutions

1997 ◽  
Vol 31 (12) ◽  
pp. 1465-1470 ◽  
Author(s):  
Yanping Zhang ◽  
Quanyun A Xu ◽  
Lawrence A Trissel ◽  
Doward L Gilbert ◽  
J Frank Martinez
Keyword(s):  
Light Beam ◽  
Chemical Stability ◽  
High Intensity ◽  
Physical Stability ◽  
Analytical Techniques ◽  
Visual Observation ◽  
Particle Content ◽  
Drug Concentrations ◽  
Normal Light ◽  
Physical And Chemical

OBJECTIVE: To evaluate the physical compatibility and chemical stability of paclitaxel at concentrations of 0.3 and 1.2 mg/mL with cisplatin 0.2 mg/mL in NaCl 0.9% injection and with carboplatin 2 mg/mL in NaCl 0.9% injection and dextrose 5% injection over 7 days at 4, 23, and 32°C. DESIGN: The test samples were prepared in polyolefin bags of the infusion solutions at the required drug concentrations. Evaluations were performed initially and after 4 hours, and 1, 3, 5, and 7 days of storage at temperatures of 4, 23, and 32°C for physical and chemical stability. Physical stability was assessed by using visual observation in normal light and using a high-intensity monodirectional light beam. In addition, turbidity and particle content were measured electronically. Chemical stability of the three drugs was evaluated by using three stability-indicating HPLC analytical techniques. RESULTS: All samples were physically stable through 1 day. However, microcrystalline precipitation of paclitaxel occurred in 3 days in some samples and within 5 days in all samples. Paclitaxel concentrations remained above 90% in all samples throughout the study. Cisplatin admixtures exhibited paclitaxel concentration-dependent decomposition with cisplatin losses of approximately 5–8% in 4 hours and approximately 20% in 1 day at 23 and 32°C in the paclitaxel 1.2 mg/mL admixtures. With paclitaxel 0.3 mg/mL in the admixtures, cisplatin losses were about 10% in 7 days at these temperatures. Carboplatin in admixtures with both concentrations of paclitaxel was stable for 7 days at 4°C, but sustained losses of about 10% and 12% in 3 days at 23 and 32°C, respectively. CONCLUSIONS: Admixtures of paclitaxel 0.3 and 1.2 mg/mL with cisplatin and carboplatin are limited in their utility time by both paclitaxel microcrystalline precipitation and decomposition of cisplatin and carboplatin. The admixture of paclitaxel 1.2 mg/mL with cisplatin 0.2 mg/mL in NaCl 0.9% injection exhibits unacceptable cisplatin loss in 24 hours. All other combinations were physically and chemically stable for at least 24 hours at 4, 23, and 32°C.

scholarly journals In situ physical and chemical characterisation of the Eyjafjallajökull aerosol plume in the free troposphere over Italy

2014 ◽  
Vol 14 (2) ◽  
pp. 1075-1092 ◽  
Author(s):  
S. Sandrini ◽  
L. Giulianelli ◽  
S. Decesari ◽  
S. Fuzzi ◽  
P. Cristofanelli ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Gamma Ray ◽  
Fine Fraction ◽  
Chemical Properties ◽  
Analytical Techniques ◽  
Ground Level ◽  
Coarse Fraction ◽  
Volcanic Plume ◽  
Physical And Chemical ◽  
Aerosol Plume

Abstract. Continuous measurements of physical and chemical properties at the Mt. Cimone (Italy) GAW-WMO (Global Atmosphere Watch, World Meteorological Organization) Global Station (2165 m a.s.l.) have allowed the detection of the volcanic aerosol plume resulting from the Eyjafjallajökull (Iceland) eruption of spring 2010. The event affected the Mt. Cimone site after a transport over a distance of more than 3000 km. Two main transport episodes were detected during the eruption period, showing a volcanic fingerprint discernible against the free tropospheric background conditions typical of the site, the first from April 19 to 21 and the second from 18 to 20 May 2010. This paper reports the modification of aerosol characteristics observed during the two episodes, both characterised by an abrupt increase in fine and, especially, coarse mode particle number. Analysis of major, minor and trace elements by different analytical techniques (ionic chromatography, particle induced X-ray emission–particle induced gamma-ray emission (PIXE–PIGE) and inductively coupled plasma mass spectrometry (ICP-MS)) were performed on aerosols collected by ground-level discrete sampling. The resulting database allows the characterisation of aerosol chemical composition during the volcanic plume transport and in background conditions. During the passage of the volcanic plume, the fine fraction was dominated by sulphates, denoting the secondary origin of this mode, mainly resulting from in-plume oxidation of volcanic SO2. By contrast, the coarse fraction was characterised by increased concentration of numerous elements of crustal origin, such as Fe, Ti, Mn, Ca, Na, and Mg, which enter the composition of silicate minerals. Data analysis of selected elements (Ti, Al, Fe, Mn) allowed the estimation of the volcanic plume's contribution to total PM10, resulting in a local enhancement of up to 9.5 μg m−3, i.e. 40% of total PM10 on 18 May, which was the most intense of the two episodes. These results appear significant, especially in light of the huge distance of Mt. Cimone from the source, confirming the widespread diffusion of the Eyjafjallajökull ashes over Europe.

Islamic Twelfth Century C.E. Glazes from Aktobe, Kazakhstan, and Comparison to Modern Practice in Afghanistan and Uzbekistan

MRS Advances ◽  
2017 ◽  
Vol 2 (39-40) ◽  
pp. 2101-2133 ◽  
Author(s):  
Pamela B. Vandiver ◽  
Sean Arnold ◽  
Yeraly Akimbek
Keyword(s):  
Analytical Techniques ◽  
Archaeological Site ◽  
Initial Study ◽  
Silk Road ◽  
Raw Material ◽  
Material Sources ◽  
The Republic ◽  
Raw Material Variability ◽  
Physical And Chemical ◽  
The Silk Road

ABSTRACT A preliminary survey of the microstructures and compositions of representative ceramic styles using minimally invasive analytical techniques provides a method of gaining insight into the materials and techniques of ceramic production dating from the eleventh to twelfth centuries C.E. at the archaeological site of Aktobe and from the 14-15th centuries C.E. at Aspara in southeastern Kazakhstan, both walled cities on the Silk Road trading corridor. The case is made for local production based on the argument of technological style or patterning of practices. Seven ceramic sherds representative of glazed earthenware and stoneware traditions were selected for study from excavations of Y. Akimbek and others that are maintained at the Institute of History and Archaeology of the Republic of Kazakhstan in Almaty. Fragments from serving bowls, a cup and bottle were studied by optical microscopy (OM), scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDS), electron beam microprobe analysis (EPMA) and refiring tests of the bodies and glazes. This initial study aims to characterize the range of physical and chemical variability of ceramics either produced at or imported into Aktobe and Aspara. Most stylistic studies consider these ceramics to have been imported from the Silk Road trade routes that connected many Central Asian cities. The styles include an imitation lusterware bowl made with a ground chromite underglaze pigment, a copper turquoise and cobalt blue and black painted white slipped alkaline-glazed cup, two green lead-glazed copper bowls, an imitation three-color of Chinese sansai bowl, a four-color lead-glazed bowl with underglaze mottled red, gray and black painted slips on a white slipped background and a stoneware bottle. Comparison of the weight ratios of the glaze compositions to possible plant ash raw material sources is presented as a possible way of studying raw material variability; however, analysis is complicated by having two other possible sources that may have supplied fluxing agents, including, salts present in the clays and salts from evaporite deposits.

Frontiers of water oxidation: the quest for true catalysts

2017 ◽  
Vol 46 (20) ◽  
pp. 6124-6147 ◽  
Author(s):  
J. Li ◽  
R. Güttinger ◽  
R. Moré ◽  
F. Song ◽  
W. Wan ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Analytical Techniques ◽  
Mechanistic Studies ◽  
Oxidation Catalysts

Development of advanced analytical techniques is essential for the identification of water oxidation catalysts together with mechanistic studies.

Stability of Imipenem-Cilastatin Sodium in AutoDose Infusion System Bags

2003 ◽  
Vol 38 (2) ◽  
pp. 130-134
Author(s):  
Lawrence A. Trissel ◽  
Quanyun A. Xu
Keyword(s):  
Sodium Chloride ◽  
Chemical Stability ◽  
High Performance ◽  
Physical Stability ◽  
Analytical Techniques ◽  
Storage Condition ◽  
Evaluation Procedure ◽  
Drug Concentrations ◽  
Physical And Chemical ◽  
Infusion System

The objective of this study was to evaluate the physical and chemical stability of imipenem-cilastatin sodium 250 mg/100 mL and 500 mg/100 mL (of each drug component) admixed in 0.9% sodium chloride injection packaged in AutoDose Infusion System bags. Triplicate test samples were prepared by bringing the required amount of imipenem-cilastatin sodium injection to volume with 0.9% sodium chloride injection. A total of 100 mL of each of the test solutions was packaged in each of three ethylene vinyl acetate (EVA) AutoDose bags designed for use in the AutoDose Infusion System for each storage condition. Samples were protected from light and evaluated at appropriate intervals for up to three days at 23°C and 14 days at 4°C. Physical stability was assessed using a multistep evaluation procedure that included turbidimetric and particulate measurement in addition to visual inspection. Chemical stability was assessed with stability-indicating high performance liquid chromatography (HPLC) analytical techniques, based on initial drug concentrations and concentrations at appropriate intervals over the study periods. The admixtures were clear throughout the study when viewed in normal fluorescent room light and with a Tyndall beam. Measured turbidity and particulate content were low initially and exhibited little change throughout the study. HPLC analysis revealed extensive decomposition in the samples, with imipenem being the less stable component. The instability of the imipenem-cilastatin sodium admixtures is consistent with previous studies. Admixtures stored under refrigeration should be used immediately upon warming to room temperature due to the rapid rate of imipenem decomposition. The AutoDose Infusion System bags were not found to affect adversely or improve the physical and chemical stability of this drug.

scholarly journals What Was Released? Assessing the Physical Properties and Chemical Composition of Petroleum and Products of Burned Oil

Oceanography ◽  
2021 ◽  
Vol 34 (1) ◽  
pp. 44-57
Author(s):  
Jürgen Rullkötter ◽  
John Farrington
Keyword(s):  
Oil Spills ◽  
Complex Mixture ◽  
Chemical Properties ◽  
Analytical Techniques ◽  
Ion Cyclotron Resonance ◽  
Model Calculations ◽  
Research Questions ◽  
Physical And Chemical ◽  
And Chemical Properties

The severity of oil spills depends on the quantity of material released and its physical and chemical properties. The total amount of petroleum spilled during the Deepwater Horizon incident and the relative fractions of the chemical compound classes of the Macondo oil were obtained by measurements, observations, and model calculations, with a significant amount of uncertainty. Because petroleum is an extremely complex mixture of many thousands or more of gaseous, liquid, and solid constituents, full elucidation of their compositions at the molecular level is impossible with presently available analytical techniques. This paper reviews published work on widely used analytical techniques and points out that scientists’ varying approaches to research questions and preferences for methods of analysis constitute a source of uncertainty. In addition, the focus is on two technical advancements developed over the last two decades, namely two-dimensional gas chromatography and Fourier transform ion cyclotron resonance mass spectrometry. Both were particularly valuable in the analysis of the spilled Macondo oil and its weathering products. Among the different processes of alteration of the original oil, only in situ oil burning is dealt with in this paper. This review reveals the paucity of data on this mitigation process and shows the need for more systematic coordination of methods in burned oil research studies.

Effects of grilling to 80°c on the physical and chemical composition of pork loin steaks

1994 ◽  
Vol 1994 ◽  
pp. 180-180
Author(s):  
J.D. Wood ◽  
G.R. Nute ◽  
R.C. Ball ◽  
G.A.J. Fursey ◽  
G. Harrington
Keyword(s):  
Chemical Composition ◽  
Live Weight ◽  
Analytical Techniques ◽  
The Other ◽  
Internal Temperature ◽  
Fat Thickness ◽  
Pork Loin ◽  
Physical And Chemical

Previous work has shown that grilling pork steaks to a high final internal temperature (80°C), which corresponds to “well done”, significantly reduces tenderness and juiciness but increases the intensity of pork flavour. This work was done to examine the effects of grilling on physical and chemical composition.Two adjacent 25 mm-thick steaks with backfat and rind attached were cut from each of 62 deboned pork loins (taken from 90 kg live weight pigs, average 11mm P2 fat thickness). One steak was analysed fresh by dissection and standard analytical techniques and the other after grilling to 80°C final internal temperature.

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