Authors:Olav Bleie, Michael F. Roberto, Thomas I. Dearing, Charles W. Branham, Olav M. Kvalheim, and Brian J. Marquardt
The Moffatt-Swern oxidation (MSO) is a multistep, versatile, metal-free reaction by which alcohols are transformed into aldehydes and ketones. Batch MSO requires low temperatures (−70 °C) due to a highly exothermic reaction step that generates intermediates. This work shows that a rigorous investigation of the MSO in batch can be used as a stepping-stone to its implementation in a continuous-flow reactor (CFR). This work has two parts: the first part details the investigation of MSO in batch; the second covers the translation of the knowledge derived from batch to a CFR. The MSO batch reaction was performed under cryogenic conditions with real-time process monitoring. The reaction was monitored with Raman spectroscopy and could be tracked throughout the reaction. All concentrations were validated using offline high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Two configurations of the CFR were produced. Configuration 1 used the traditional batch methodology in terms of reagent addition and reaction conditions. Configuration 2 used the information derived from the batch reaction, changing the order of the reagent addition and increasing the temperature of the reactor. Real-time quantitative monitoring of chemical yield in the CFR was demonstrated via Raman spectroscopy and partial least squares (PLS) regression modeling. Reaction yield was accurately predicted every 15 s, reducing the need for chromatographic validation once the model was built. Configuration 2 was shown to perform comparably to configuration 1 at low temperature and far outperforming it at higher temperatures. Both CFR configurations performed significantly better than the batch setup in terms of temperature and yield, as was expected.
A computer program is presented, which locates peaks in high-resolution γ-ray spectra and determines their content. The program
has been written in Basic; ‘translations’ have been made into Fortran and Algol.
Authors:W. James, T. Raghvan, T. Gentry, G. Shan, and R. Loeppert
Sensitivities for the measurement of four arsenic species, AsIII, AsV, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), in environmental waters and rice extracts by a new neutron
activation analysis (NAA) method using pre-separation of the species by liquid chromatography were determined. A manual fraction
collection was used to isolate the species, followed by instrumental neutron activation analysis procedures. The sensitivities
determined for arsenic species in the samples varied from 1.21 to 1.47 ng per vial or about 30 μg·L−1 in sample solutions which translates to about 900 ng arsenic per gram of rice for our HPLC-NAA experiments.
The feasibility of measuring total body carbon (TBC) based on prompt-gamma activation analysis (PGAA) of the human body was
examined. Preliminary analyzes for 33 healthy pre-menopausal women indicated a range of TBC values (7.1±4.4 kg) which translated
to 17.1±6.5 kg body fat (27.9%±7.9% of body weight). An advantage of the PGAA measurement is that fat mass can be obtained
simultaneous with that of total body protein mass, both indices serving as useful body composition markers of the nutritional
The promise associated with early ancient DNA results has not been translated into routine techniques of value to archaeologists. The reasons for this are partly technical - ancient DNA analysis is an extremely difficult technique - and partly practical - ancient DNA analysis is often an after thought to an archaeological project. In this paper ancient human DNA analysis is briefly reviewed paying particular attention to specimens originating from Greek archaeological contexts. Problems commonly encountered during ancient DNA research are summarised and recommendations for future strategies in the application of ancient DNA in archaeology are proposed.
Authors:L. Lugo, M. Comuñas, E. López, and J. Fernández
New densities are reported over the whole composition range for 1-iodoperfluorohexane+n-octane system at temperatures from 288.15 to 308.15
K at atmospheric pressure. These data have been used to compute the excess
molar volumes, VmE.
Large positive VmE
values have been obtained over the entire range of composition, which increases
when the temperature rises. The experimental data were used to calculate the
isobaric thermal expansivity, and the quantities (∂VmE/∂T)p and (∂HmE/∂p)T. Furthermore,
the results have been used to investigate the volumetric prediction ability
of the equations of state Soave–Redlich–Kwong, Peng–Robinson,
Patel–Teja and Soave–Redlich–Kwong with volume translation.
The fluorine contents of plastics, ranging from about 20 μg·g−1 to 66%, may be measured instrumentally using a conventional research nuclear reactor, an automated sample irradiation and
counting system, and a set of well-calibrated, in-house, fluorine standards. Plastics with low to medium fluorine contents
may be analyzed using 20F by placing the gamma-ray detector at appropriate distances from the irradiated sample. For high-F plastics, samples may
be irradiated in a cadmium lined irradiation site, using 19O and 20F. Counting statistics of <3% translate into reproducibility of measurements within ±3% and analytical accuracies of ±1% to
Authors:Gary Perkins, Omar Khatib, Matthew Peterson, Annukka Kallinen, Tien Pham, Alison Ung, Ivan Greguric, and Giancarlo Pascali
Carbon dioxide chemistry is an area of continuing growth in recent times, due to socioeconomic and environmental reasons. Several methods have now been reported for obtaining N-methylation on primary and secondary amines directly from CO2. We have translated in two microfluidic setups (Slug Flow [SF] and Tube-in-Tube [TiT]) a ruthenium (Ru)-catalyzed process previously reported using a pressure vessel. Here, we demonstrate how the SF approach is more efficient but requires more input to reach a steady state, while the TiT system is less efficient but more tuneable.We have tested these processes on three model amines and two radiopharmaceutical precursors that are routinely used in 11C chemistry. The microfluidic processes tested are also potentially more efficient than the pressure vessel counterpart, in terms of amount of Ru catalyst needed (1% vs. 10%) and projected reaction completion time.
Authors:Sarah E. Smith, Zachary J. Huba, Fahad Almalki, J. R. Regalbuto, John Monnier, and Everett E. Carpenter
Magnetic nanomaterials have many applications in the fields of catalysis, medicine, and environmental studies. An emerging synthetic method capable of large-scale production of nanomaterials is a continuous-flow microreactor. However, translating known conventional benchtop reactions to a continuous-flow system can be difficult; reaction parameters such as reaction time and viscosity of the solution are significant limitations in flow-based systems. In this study, nanocrystalline Cu—Ni and Cu—Co core—shell materials were successfully synthesized using a capillary microreactor in a one-step process. Ethanol was used as solvent, allowing for faster reaction times and reduced reaction solution viscosity, compared to similar bench top synthetic protocols. Both nanocomposites were tested for activity in Fischer—Tropsch and showed activity above 220 °C. This study shows that a continuous-flow capillary microreactor has the capabilities to make complex metallic nanomaterials at short reaction times with proper selection of reaction solvent systems.