Closed Reaction Vessel Research Articles

Julian Hirniak, an early proponent of periodic chemical reactions

In this article we present and discuss the work and scientific legacy of Julian Hirniak, the Ukrainian chemist and physicist who published two articles in 1908 and 1911 about periodic chemical reactions. Over the last 110+ years, his theoretical work has often been cited favorably in connection with Alfred Lotka’s theoretical model of an oscillating reaction system. Other authors have pointed out thermodynamic problems in Hirniak’s reaction scheme. Based on English translations of his 1908 Ukrainian and 1911 German articles, we show that Hirniak’s claim (that a cycle of inter-conversions of three chemical isomers in a closed reaction vessel can show damped periodic behavior) violates the Principle of Detailed Balance (i.e., the Second Law of Thermodynamics), and that Hirniak was aware of this Principle. We also discuss his results in relation to Lotka’s first model of damped oscillations in an open system of chemical reactions involving an auto-catalytic reaction operating far from equilibrium. Taking hints from both Hirniak and Lotka, we show that the mundane case of a kinase enzyme catalyzing the phosphorylation of a sugar can satisfy Hirniak’s conditions for damped oscillations to its steady state flux (i.e., the Michaelis–Menten rate law), but that the oscillations are so highly damped as to be unobservable. Finally, we examine historical and factual misunderstandings related to Julian Hirniak and his publications.

Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition: Plastic Package Degradation, Speciation of Nano-TiO2, and Environmental Impact Assessment

Light emitting diodes (LEDs) have accounted for most of the lighting market as the technology matures and costs continue to reduce. As a new type of e-waste, LED is a double-edged sword, as it contains not only precious and rare metals but also organic packaging materials. In previous studies, LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials. Unlike crushing and other traditional methods, hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials. This work developed a closed reaction vessel, where the degradation rate of plastic polyphthalamide (PPA) was close to 100%, with nano-TiO2 encapsulated in plastic PPA being efficiently recovered, while metals contained in LED were also recycled efficiently. Besides, the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work. Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes. Especially the developed method could reduce more than half the impact of global warming. Furthermore, this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices, such as integrated circuits.

NIR II Light-Response Au Nanoframes: Amplification of a Pressure- and Temperature-Sensing Strategy for Portable Detection and Photothermal Therapy of Cancer Cells.

Quantitative detection of cancer cells using portable devices is promising for the development of simple, fast, and point-of-care cancer diagnostic techniques. However, how to further amplify the detection signal to improve the sensitivity and accuracy of detecting cancer cells by portable devices remains a challenge. To solve the problem, we, for the first time, synthesized folic-acid-conjugated Au nanoframes (FA-Au NFs) with amplification of pressure and temperature signals for highly sensitive and accurate detection of cancer cells by portable pressure meters and thermometers. The resulting Au NFs exhibit excellent near-infrared (NIR) photothermal performance and catalase activity, which can promote the decomposition of NH4HCO3 and H2O2 to generate corresponding gases (CO2, NH3, and O2), thereby synergistically amplifying pressure signals in a closed reaction vessel. At the same time, Au NFs with excellent peroxidase-like activity can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce TMB oxide (oxTMB) with a strong photothermal effect, thereby cooperating with Au NFs to amplify the photothermal signal. In the presence of cancer cells with overexpressing folate receptors (FRs), the molecular recognition signals between FA and FR can be converted into amplified pressure and temperature signals, which can be easily read by portable pressure meters and thermometers, respectively. The detection limits for cancer cells using pressure meters and thermometers are 6 and 5 cells/mL, respectively, which are better than other reported methods. Moreover, such Au NFs can improve tumor hypoxia by catalyzing the decomposition of H2O2 to produce O2 and perform photothermal therapy of cancer. Together, our work provides new insight into the application of Au NFs to develop a dual-signal sensing platform with amplification of pressure and temperature signals for portable and ultrasensitive detection of cancer cells as well as personalized cancer therapy.

On the quasi-steady-state approximation in an open Michaelis-Menten reaction mechanism.

The conditions for the validity of the standard quasi-steady-state approximation in the Michaelis–Menten mechanism in a closed reaction vessel have been well studied, but much less so the conditions for the validity of this approximation for the system with substrate inflow. We analyze quasi-steady-state scenarios for the open system attributable to singular perturbations, as well as less restrictive conditions. For both settings we obtain distinguished invariant manifolds and time scale estimates, and we highlight the special role of singular perturbation parameters in higher order approximations of slow manifolds. We close the paper with a discussion of distinguished invariant manifolds in the global phase portrait.

Pressure and Fluorescence Dual Signal Readout CuO-NiO/C Heterojunction Nanofibers-Based Nanoplatform for Imaging and Detection of Target Cancer Cells in Blood

The development of multifunctional nanoplatform, which integrates biosensing and imaging diagnosis, for accurate identification of cancer cells in blood or other bodily fluids is critical for early cancer diagnosis and treatment. Herein, by using a facile single spinneret electrospinning technique followed by thermal treatment, CuO-NiO/C heterojunction nanofiber was synthesized. The resultant CuO-NiO/C nanofibers exhibited excellent catalytic activity toward ammonia borane (AB) hydrolysis, producing a marked pressure increase in a closed reaction vessel. Moreover, the resultant nanofibers showed highly efficient catalytic activity for reduction of rhodamine 6G (Rh6G, fluorescent molecule), accompanied by the fluorescence quenching. On the basis of these findings, a novel sensing platform utilizing folic-acid (FA) conjugated CuO-NiO/C nanofibers as an artificial enzyme and recognition element for fluorescence imaging and pressure-based (pressure meter) detection of folate receptor (FR)-positive cancer cell...

The new frontier of diagnostics: Molecular assays and their role in infection prevention and control.

Recent advances in technology over the last decade have propelled the microbiology laboratory into a pivotal role in infection prevention and control. The rapid adaptation of molecular technologies to the field of clinical microbiology now greatly influences infectious disease management and significantly impacts infection control practices. This review discusses recent developments in molecular techniques in the diagnosis of infectious diseases. It describes the basic concepts of molecular assays, discusses their advantages and limitations, and characterizes currently available commercial assays with respect to cost, interpretive requirements, and clinical utility.

A norovirus detection architecture based on isothermal amplification and expanded genetic systems

Noroviruses are the major cause of global viral gastroenteritis with short incubation times and small inoculums required for infection. This creates a need for a rapid molecular test for norovirus for early diagnosis, in the hope of preventing the spread of the disease. Non-chemists generally use off-the shelf reagents and natural DNA to create such tests, suffering from background noise that comes from adventitious DNA and RNA (collectively xNA) that is abundant in real biological samples, especially feces, a common location for norovirus. Here, we create an assay that combines artificially expanded genetic information systems (AEGIS, which adds nucleotides to the four in standard xNA, pairing orthogonally to A:T and G:C) with loop-mediated isothermal amplification (LAMP) to amplify norovirus RNA at constant temperatures, without the power or instrument requirements of PCR cycling. This assay was then validated using feces contaminated with murine norovirus (MNV). Treating stool samples with ammonia extracts the MNV RNA, which is then amplified in an AEGIS-RT-LAMP where AEGIS segments are incorporated both into an internal LAMP primer and into a molecular beacon stem, the second lowering background signaling noise. This is coupled with RNase H nicking during sample amplification, allowing detection of as few as 10 copies of noroviral RNA in a stool sample, generating a fluorescent signal visible to human eye, all in a closed reaction vessel.

Lithographically Cut Multiwalled Carbon Nanotubes: Opening Caps, Controlling Length Distribution, and Functionalization

This work presents a microwave digestion heating method using a 40 ml mixture of potassium permanganate and sulfuric acid (3/1 mol) to cut, end-open, and functionalize as-prepared multiwalled carbon nanotubes (A-MWCNTs). Also, the ability of the microwave digestion method was studied at different reaction times (5, 10, 20, 30, and 40 minutes). To harness the extent of treatment, shortened multiwalled carbon nanotubes (S-MWCNTs) were fully characterized by UV-visible, Fourier transform infrared spectroscopy, and Raman spectroscopies, as well as, transmission electron microscopy and optical microscopy. The results showed that, with this mild treatment, the A-MWCNTs (>80 µm) were efficiently and significantly shortened to below 1 µm after 40 minutes. Also, heating the closed reaction vessel under microwave irradiation at 90°C for 20 minutes was very effective in the functionalization of MWNTs. At the same time, the S-MWCNTs formed the best state of dispersion in water without the help of surfactants that provided possibility for further functionalizations. For the first 10 minutes, crystallinity increased then decreased until 20 minutes, and after that improved slightly. Finally, the mechanism of this process is explained schematically. This method could be used as high-efficiency and damage-free process to the cut, end-open, and functionalization of CNTs that led to dispersion of CNTs and ultimately for such application.

Poly(ϵ‐caprolactone) by Combined Ring‐Opening Polymerization and Polycondensation

AbstractNumerous water‐initiated polymerizations of ϵCL are conducted in bulk with variation of catalyst, reaction time, and temperature. The conversions are determined by 1H NMR and the molar masses by SEC measurements. For polymerizations at 100 °C, Bi triflate and Hf triflate are used as catalysts, whereas at 140 °C, Al triflate, Sn(II) triflate, SnCl2, HfCl4, BiCl3, and LaCl3 are used. In addition to a closed reaction vessel, experiments are also performed with stirring in a vacuum. Under these conditions, the best catalyst (SnCl2) yields 2–3 times higher molar masses and mass spectra indicate a significant higher fraction of cyclic polymers. The results prove that a modification of the procedure may stimulate a polycondesation process without change of catalyst, time, and temperature.

Synthesis of [Co/LiF/C] nanocomposite and its application as cathode in lithium-ion batteries

[Co/LiF/C] nanocomposite has been synthesized by pyrolysis of a cobaltocene/LiF mixture at 700°C in a closed reaction vessel under argon atmosphere. The morphology, structure and composition of the material was characterized by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen physisorption measurement (BET) and elemental analysis. The composite is comprised of hexagonally closed packed (hcp) and face centred cubic (fcc) cobalt nanoparticles and LiF, which are embedded in a matrix of graphitic nanostructures. The composite has both micro- (0.05cm3g−1) and mesopores (0.1cm3g−1), and exhibits a BET surface area of 177m2g−1. Electrochemical characterizations were performed versus lithium to determine the capacity, cyclic stability and to investigate the reaction mechanism. At a given current density of 27.8mAg−1 the composite electrode exhibits an initial specific discharge capacity of 152mAhg−1 (based on cobalt and fluorine content) which stabilizes at about 170mAhg−1 over 70cycles.

Synthesis and characterization of core/shell structured nanophosphors CePO4:Tb@LaPO4 by solvothermal method

Core/shell structured CePO4:Tb(III)@LaPO4 and CePO4:Tb(III) were successfully synthesized in tris(2–ethylhexyl) phosphate (TEHP) and diethylene glycol (DEG) solvents for comparison of the two techniques in open air and closed reaction vessel. Morphology and crystal structure of the core/shell nanophosphors were determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM), which showed that nanophosphors had diameter of about 5–10 nm with the monoclinic monazite phase. The nanophosphors obtained by close vessel procedure showed smaller size, more homogeneity and pure crystallite. The luminescent measurements were done upon the different excitation wavelengths in ultraviolet region and at room temperature to elucidate the influences of the used solvents and the reaction temperatures. It was found that CePO4:Tb@LaPO4 prepared by the close vessel synthesis showed the intensity of green band of the transfer from 5D4 to 7F5 energy level, which was strongly increased, and the luminescent decay time was 3.2 ms, which was longer than that of naked CePO4:Tb phosphor.

Monodisperse Upconverting Nanocrystals by Microwave-Assisted Synthesis

Upconverting nanocrystals have a tremendous potential for applications in fields such as bioanalysis, medical therapy, or display technologies. However, a prerequisite for many applications is the availability of small, monodisperse, and highly luminescent nanocrystals. Here we show, that a microwave-assisted synthesis approach allows for the synthesis of such monodisperse and luminescent upconverting nanocrystals within 5 min in a closed reaction vessel. Even though the same reactants and solvents as with classical conductive heating reactions were used, microwave-assisted synthesis resulted in differently sized and shaped particles and provided superior reaction control. The nucleation and growth mechanism follows a La Mer scheme and can be controlled extremely accurately. It is expected that the fundamental principles of this synthesis approach can be applied to many other types of nanocrystals as well.

A Quick and Accurate Oxygen-Based Pressure-Sensor Assay for Catalase Activity

A method is described for investigating the catalytic decomposition of hydrogen peroxide by using a computer-interfaced pressure sensor to follow the evolution of O2(g) inside a closed reaction vessel. The pressure sensor and accompanying glassware are readily available in many chemistry labs or can be obtained at a relatively low cost. The method is particularly suited for kinetic studies of the enzymatic action of catalase on H2O2, which is known to follow the Michaelis–Menton mechanism. Appropriate for use with undergraduate chemistry students in physical chemistry or biochemistry, the data collection and analysis can be accomplished in one three-hour lab meeting. In comparison to other methods that have been recommended for catalase–H2O2 studies, the electronic pressure-sensor approach offers a number of advantages that allow for a reliable determination of the Michaelis–Menton constant in this system.

Recovery of locked-up uranium in slag disc by co-melting in magnesio-thermic reduction

Magnesio-thermic Reduction (MTR) of Uranium tetra Fluoride (UF4) is one of the main industrial methods for producing commercial pure uranium metal in massive form. Nuclear grade natural Uranium (U) metal ingots are produced regularly in UED, BARC following MTR route for fuelling research reactors in BARC. This is a bomb type reaction and is represented by $$UF_4 + 2Mg = U + 2MgF_{2 - } (\Delta H^ \circ _{298} = - 83.5 Kcal/gm mole)$$ Small excess of magnesium is required to achieve maximum yield. This thermite type reduction is carried out in a closed reaction vessel, popularly known as MTR reactor, lined with magnesium fluoride powder. MTR reactors are made of boiler quality steel. Use of MgF2, a reaction by-product, as lining material completely eliminates the chance of foreign element contamination. This lining of MgF2 not only prevents direct contact of the molten metal and slag with the reaction vessel but also acts as an insulating material immediately after firing and holds the hot molten mass for longer period, thereby facilitating adequate metal-slag separation. This is a batch process and stoichiometric quantity of UF4 and Mg chips are blended and charged inside the lined reactor. Once the charging is over, the surface is covered with fine MgF2 powder and sealed by fixing a lid. This sealed reactor is then heated inside an electric furnace at a predefined heating schedule for the reduction to take place. The initiation of reaction is called ‘Firing”.

A process for production of titanium aluminide: Reaction mechanism

A new combustion synthesis process for production of TiAl from TiO2, Al, Ca and KClO4 has been developed. In a closed reaction vessel, this process gets started at about 505°C with the reaction between Ca and KClO4 yielding CaO and KCl. Subsequent two-stage reaction between TiO2 and Al leads to formation of titanium aluminides and α-Al2O3. Then the reaction between α-Al2O3 and CaO results in formation of CaAl4O7 (grossite). The overall reaction scheme can be represented as 6TiO2 + 22Al + 4KClO4 + 4Ca = 6TiAl + 4CaAl4O7 + 4KCl. The temperature reached in the process (1950°C) is high enough for the melting of TiAl and CaAl4O7 and evaporation of KCl.

Intermolecular and Intramolecular, Platinum‐Catalyzed, Acceptorless Dehydrogenative Coupling of Hydrosilanes with Aryl and Aliphatic Methyl C—H Bonds.

Intermolecular acceptorless dehydrogenative coupling of silanes with arene C−H bonds and intramolecular coupling of silanes with aryl and alkyl C−H bonds occur in good yield in the presence of 5 mol % of TpMe2PtMe2H (TpMe2 = hydridotris(3,5-dimethylpyrazolyl)borate) and related platinum(IV) complexes. The intermolecular reactions of arenes occurred with both trialkyl and dialkylaryl silanes. Intramolecular reactions of dialkylsilylalkylarenes occurred at aryl C−H bonds, and reactions of tributylsilane or dibutylphenylsilane occurred intramolecularly at the aliphatic, primary C−H bond. The reactions of arenes occurred preferentially at the least sterically hindered C−H bonds and preferentially with more electron-poor arenes. Crossover experiments and the lack of reactivity of the arylsilanes with H2 imply that the dehydrogenative silylation of arenes can be irreversible, even in a closed reaction vessel.

Intermolecular and Intramolecular, Platinum-Catalyzed, Acceptorless Dehydrogenative Coupling of Hydrosilanes with Aryl and Aliphatic Methyl C−H Bonds

Intermolecular acceptorless dehydrogenative coupling of silanes with arene C-H bonds and intramolecular coupling of silanes with aryl and alkyl C-H bonds occur in good yield in the presence of 5 mol % of TpMe2PtMe2H (TpMe2 = hydridotris(3,5-dimethylpyrazolyl)borate) and related platinum(IV) complexes. The intermolecular reactions of arenes occurred with both trialkyl and dialkylaryl silanes. Intramolecular reactions of dialkylsilylalkylarenes occurred at aryl C-H bonds, and reactions of tributylsilane or dibutylphenylsilane occurred intramolecularly at the aliphatic, primary C-H bond. The reactions of arenes occurred preferentially at the least sterically hindered C-H bonds and preferentially with more electron-poor arenes. Crossover experiments and the lack of reactivity of the arylsilanes with H2 imply that the dehydrogenative silylation of arenes can be irreversible, even in a closed reaction vessel.

Primary Amine and Solvent‐Induced Polymerizations of L‐ or D,L‐Phenylalanine N‐Carboxyanhydride

AbstractSummary: Benzylamine, hexylamine and aniline‐initiated polymerizations of D,L‐phenylalanine and L‐phenylalanine N‐carboxyanhydride (D,L‐Phe‐NCA and L‐Phe‐NCA) were performed in various solvents. The isolated polypeptides were characterized by MALDI‐TOF mass spectroscopy. Exclusively linear polypeptides having one amide and one amino endgroup were found, when the polymerizations were conducted in a closed reaction vessel with dioxane or sulfolane as reaction media. Traces of water competed with aniline as initiator, when the reaction vessel was closed with a drying tube. In N,N‐dimethylformamide (DMF) formyl endgroups were formed at polymerization temperatures of 60 °C. In DMF and N‐methylpyrrolidone, cyclic oligo‐ and polypeptides were formed by a solvent‐induced polymerization initiated by zwitterions, which may compete with the primary amine‐initiated polymerizations.MALDI‐TOF mass spectrum of a poly(D,L‐phenylalanine) polymerized in NMP without addition of an initiator.magnified imageMALDI‐TOF mass spectrum of a poly(D,L‐phenylalanine) polymerized in NMP without addition of an initiator.

Purification of multi-walled carbon nanotubes through microwave heating of nitric acid in a closed vessel

We demonstrate that microwave-assisted heating in 5 mL of nitric acid eliminates impurities, such as amorphous carbon, carbon nanoparticles, and metals, from multi-walled carbon nanotubes (MWNTs). Heating the closed reaction vessel under microwave irradiation at 160 °C for 30 min is a very effective means of purifying the MWNTs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm that these reaction conditions are beneficial for removing the impurities and ensuring that the MWNTs remain intact. In contrast, a purification temperature of 180 °C provides too strongly oxidizing conditions that destroy the MWNTs. The ratio of the G and D bands in the Raman spectra also confirms that a temperature of 160 °C is optimal. The defect peak that we observed in the differential thermogravimetry (DTG) analysis of the raw material was not present after microwave purification. The presence of metal impurities in the MWNTs can be reduced significantly when using this method.

金属ニッケル触媒によるポリクロロベンゼンの水素化分解反応

In a closed reaction vessel, chlorobenzenes were exclusively hydrodechlorinated to give benzene in the presence of zinc powder, water, sodium hydroxide, and a catalytic amount of metallic nickel in ethanol under nitrogen atmosphere. The reaction was accelerated by adding excess zinc powder, water, and stoichiometric amount of sodium hydroxide to the catalyst system. Water was a hydrogen source and sodium hydroxide was a trapping reagent of hydrochloric acid produced. A probable reaction pathway was presented.