Nitroethane Research Articles

Hazard characterization of carcinogenicity, mutagenicity, and reproductive toxicity for short chain primary nitroalkanes.

Nitroalkanes are organic aliphatic hydrocarbon compounds with a nitro moiety that are commonly used as solvents or intermediates to synthesize a variety of organic compounds due to their inherent reactivity. In June 2020, a harmonized classification and labeling (CLH) proposal was submitted to the European Chemicals Agency (ECHA) for the following harmonized carcinogenicity, mutagenicity, and reproductive toxicity ("CMR") classifications for nitromethane (NM), nitroethane (NE), and 1-nitropropane (1-NP): NM Carc. 1B and Repr. 1B; NE Repr. 1B; and 1-NP Repr. 2. In this assessment, a weight of evidence (WoE) evaluation of studies on animal carcinogenicity and reproductive and developmental toxicity, genotoxicity, and mode of action for these three nitroalkanes was performed to critically assess the relevance of the proposed CMR classifications. Overall, the WoE indicates that NM, NE, and 1-NP are not carcinogenic, genotoxic, nor selective reproductive or developmental toxicants. Based on our analysis, classifying NM, NE, and 1-NP as Category 2 reproductive toxicants is most appropriate. Furthermore, not classifying NE and 1-NP with respect to their carcinogenicity is appropriate based on the available studies for this endpoint coupled with negative results in genotoxicity studies, metabolism data, and in silico predictions. We determined that the classification for NM of Carc. 1B is not appropriate, based on the fact that rat mammary and harderian tumors are likely not relevant to humans and lung and liver tumors reported in mice were equivocal in their dose-response and statistical significance.

Rumen Methanogenesis, Rumen Fermentation, and Microbial Community Response to Nitroethane, 2-Nitroethanol, and 2-Nitro-1-Propanol: An In Vitro Study.

Simple SummaryThe present study comparatively investigates the inhibitory difference of nitroethane (NE), 2-nitroethanol (NEOH), and 2-nitro-1-propanol (NPOH) on in vitro rumen fermentation, microbial populations, and coenzyme activities associated with methanogenesis. The results showed that both NE and NEOH were more effective in reducing ruminal methane (CH4) production than NPOH. This work provides evidence that NE, NEOH, and NPOH were able to inhibit methanogen population and dramatically decrease methyl-coenzyme M reductase gene expression and the content of coenzymes F420 and F430 with different magnitudes in order to reduce ruminal CH4 production.Nitroethane (NE), 2-nitroethanol (NEOH), and 2-nitro-1-propanol (NPOH) were comparatively examined to determine their inhibitory actions on rumen fermentation and methanogenesis in vitro. Fermentation characteristics, CH4 and total gas production, and coenzyme contents were determined at 6, 12, 24, 48, and 72 h incubation time, and the populations of ruminal microbiota were analyzed by real-time PCR at 72 h incubation time. The addition of NE, NEOH, and NPOH slowed down in vitro rumen fermentation and reduced the proportion of molar CH4 by 96.7%, 96.7%, and 41.7%, respectively (p < 0.01). The content of coenzymes F420 and F430 and the relative expression of the mcrA gene declined with the supplementation of NE, NEOH, and NPOH in comparison with the control (p < 0.01). The addition of NE, NEOH, and NPOH decreased total volatile fatty acids (VFAs) and acetate (p < 0.05), but had no effect on propionate concentration (p > 0.05). Real-time PCR results showed that the relative abundance of total methanogens, Methanobacteriales, Methanococcales, and Fibrobacter succinogenes were reduced by NE, NEOH, and NPOH (p < 0.05). In addition, the nitro-degradation rates in culture fluids were ranked as NEOH (−0.088) > NE (−0.069) > NPOH (−0.054). In brief, the results firstly provided evidence that NE, NEOH, and NPOH were able to decrease methanogen abundance and dramatically decrease mcrA gene expression and coenzyme F420 and F430 contents with different magnitudes to reduce ruminal CH4 production.

The Antimethanogenic Nitrocompounds Can be Cleaved into Nitrite by Rumen Microorganisms: A Comparison of Nitroethane, 2-Nitroethanol, and 2-Nitro-1-propanol.

A class of aliphatic short chain nitrocompounds have been reported as being capable of CH4 reduction both in vitro and in vivo. However, the laboratory evidence associated with the metabolic fate of nitrocompounds in the rumen has not been well documented. The present study was conducted to compare in vitro degradation and metabolism of nitroethane (NE), 2-nitroethanol (NEOH), and 2-nitro-1-propanol (NPOH) incubated with mixed rumen microorganisms of dairy cows. After 10 mM supplementation of nitrocompounds, a serious of batch cultures were carried out for 120 h under the presence of two substrates differing in the ratio of maize meal to alfalfa hay (HF, 1:4; LF, 4:1). Compared to the control, methane production was reduced by 59% in NPOH and by >97% in both NE and NEOH, and such antimethanogenic effects were more pronounced in the LF than the HF group. Although NE, NEOH, and NPOH addition did not alter total VFA production, the rumen fermentation pattern shifted toward increasing propionate and butyrate and decreasing acetate production. The kinetic disappearance of each nitrocompound was well fitted to the one-compartment model, and the disappearance rate (k, %/h) of NE was 2.6 to 5.2 times greater than those of NEOH and NPOH. Higher intermediates of nitrite occurred in NEOH in comparison with NPOH and NE while ammonia N production was lowest in NEOH. Consequently, a stepwise accumulation of bacterial crude protein (BCP) in response to the nitrocompound addition was observed in both the HF and LF group. In brief, both NE and NEOH in comparison with NPOH presented greater antimethanogenic activity via the shift of rumen fermentation. In addition, the present study provided the first direct evidence that rumen microbes were able to cleave these nitrocompounds into nitrite, and the subsequent metabolism of nitrite into ammonia N may enhance the growth of rumen microbes or promote microbial activities.

Novel Nitro-Heterocycles Sugar and Indoles Candidates as Lead Structures Targeting HepG2 and A549 Cancer Cell Lines

Background: The synthesis of novel Mannich bases of nitro alkanes utilizing mono- and diamino sugar is abundant in the literatures. The new bases have been successfully synthesized and fully characterized. Biological investigations, particularly cytotoxic activity of our novel compounds were made against some cancer cell lines. With an attempt to improve the anticancer activity we decide to include the indole moieties (well known as anticancer agent) along with nitro function. Method: Investigation of the synthesized derivatives and studying their cytotoxicity against a range of cancer cell lines; such as Hep G2 (liver hepatocellular carcinoma), PC3 (human prostate cancer cells), HCT116 (human colorectal carcinoma), MCF-7 (breast cancer cell lines) and A549 (human lung carcinoma) revealed an inhibitory effect ranged from potent to weak activity in comparison with Doxorubicin; a well-known currently used drug for treatment of several types of cancer. DNA-damage determination was further explored for HepG2 cell lines that previously treated with the most active derivatives using Comet assay (SCGE). Results: Accordingly some compounds showed good activity against A-549 and HepG2 cancer cell lines in comparison with the well-known cytotoxic drug [Doxorubicin]. As a result the current research introduces novel compounds expected to serve as lead structures of potential therapeutics for cancer. Conclusion: The present paper deals with Mannich reaction of nitro methane and/or nitro ethane with formaldehyde and well known sugar mono-/di- amines result in novel nitro-heterocycles polyhydroxy Mannich basses of type 4, 5 and 9-12. Some new polyhydroxy nitro-Mannich basses have been investigated for its reactivity such as reduction, acetylation and condensation afforded structures variety. Indole ring has been introduced with the nitro functional to enhance the anticancer activity through some condensation reactions with nitro alkanes. The synthesized compounds have been confirmed by different means of analytical and spectral data. Biological investigations, particularly cytotoxic activity of our novel compounds were made against some cell lines [A-549, MCF-7, HCT-116, HepG2 and PC3], in comparison with the well-known cytotoxic drug [Doxorubicin] to discover their impact as new inhibitors in cancer therapy. DNA-damage determination was further explored for HepG2 cell lines that previously treated with the most active derivatives 6 and 7, using Comet assay (SCGE). As a result of all preceding examinations, we introduce novel compounds which expected to serve as lead structures for new series of potential therapeutics for cancer. Keywords: Mannich reaction, bis-glycosides, D-glucamines, anticancer activity, HepG2 and A549, comet assay.

Modelling and optimization of exhaust pollutants and the properties and characteristics of ethanol‐diesel through a statistical approach

AbstractThis work assesses the influence of diesel additives on chemico‐physical properties (flash point, density, viscosity, and cetane number) and exhaust emissions (CO, CO2, nitrogen oxides, and soot). Experimental tests are performed in a 4‐cylinder turbocharged, common rail direct injection engine. Experiments are conducted in different percentages of ethanol (5 and 10 %) and nitrogenate additives (2 and 5 %). The current essay applies various types of tertiary additives (nitro methane, nitro ethane, and 2‐methoxy ethyl ether). All the compositions of ethanol in the diesel make the cetane index, flash point, density, and viscosity reduce. In contrast, these properties get enhanced by adding tertiary additives. Experimental studies demonstrate that nitro ethane is more effective on the decrease of soot emissions and the increase of CO, CO2, and nitrogen oxides.

Mechanism of three phase separation in the ternary system of a polymer in a mixed solvent

Abstract The three phase separation due to contact between binodals was observed for the ternary system nitroethane(NE) + methylcyclohexane(MCH) + polystyrene(PS) with the molecular weight (Mw = 9.64 × 104 g/mol). A phase equilibrium experiment was made to determine binodals and three phase triangles on a composition triangle. With decreasing temperature a binodal spreads out from the MCH-PS side of a composition triangle at 48.4 °C and reaches the NE-MCH side at 23.6 °C. Another binodal spreads out from the NE-PS side at 43.6 °C and makes contact with the binodal running between the MCH-PS and NE-MCH sides at 3.3 °C. Simultaneously with the contact the three phase separation appears. The contact occurs at the critical point of the former binodal and at a noncritical point of the latter. The three phase separation usually occurs due to projection of a new binodal from the two phase region.

Investigating the influence of additives-fuel on diesel engine performance and emissions: Analytical modeling and experimental validation

In this study, the effect of ethanol–diesel blends with different types of additives on performance and exhaust emission is experimentally investigated through experimental modeling and optimization methods. Experiments are performed on a turbocharged common rail direct injection (CRDI) engine. The modeling is used to optimize the emission, engine performance, and physico-chemical properties by implementing factorial design considering four main parameters, namely, choice of oxygenate and nitrogenate such as Nitroethane (NE), Nitromethane (NM) and 2-methoxy ethyl ether (MXEE) and metal additives such as Manganese (MN) and Cerium (CE), engine speed (2200 and 1500rpm) and load (370, 275, 180 and 20Nm). Findings by modeling show that the quadric and cubic terms of these four variables had significant effects. The obtained results prove that using the diesel–ethanol–(NE+MN) is better to decrease soot emissions and increase cetane number. The properties under study were cetane number and viscosity experiment. The emissions decrease with increasing the engine speed. The effect of blending (MXEE+CE) with diesel–ethanol on improvement of the engine performance is higher than other additives. The optimal conditions are found to be the NE, MN, engine speed and load of 1500rpm and 168Nm, respectively. Under these conditions, the model estimated the soot content, formation of NOx and CO2, brake specific fuel consumption (BSFC) and powers of 27.6, 441.3, 28.1ppm, 224.2g/kWh and 26.5kw, respectively. The modeling techniques and developed models can be employed as a useful tool for design and optimization of appropriate ethanol–diesel fuels with effective performance for various industrial applications.

Host-guest interaction dictated selective adsorption and fluorescence quenching of a luminescent lightweight metal-organic framework toward liquid explosives.

In this article, we report the successful preparation of a Mg-based luminescent MIL-53 metal-organic framework (MOF), namely [Mg2(BDC)2(BPNO)]·2DMF (1) (BDC = 1,4-benzene dicarboxylate, BPNO = 4,4'-dipyridyl-N,N'-dioxide, DMF = N,N-dimethylformamide) in a mixed solvent containing a 2 : 3 volume ratio of DMF and ethanol (EtOH) under solvothermal conditions. Desolvated compound 1a can be used as an absorbent for selective adsorption and separation of liquid explosives, including nitroaromatic (nitrobenzene (NB)) and nitroaliphatic (nitromethane (NM) and nitroethane (NE)) compounds, through single crystal-to-single crystal (SC-SC) transformations. As one of the weakly luminescent MOFs, the luminescence of compound 1a could be quenched by the incorporation of the three liquid nitro explosives. On the basis of single crystal analysis, we provide direct evidence that both the selective adsorption and fluorescence quenching of the desolvated compound 1a are dictated by host-guest interactions between guest liquid explosives and the host framework. Such findings differ from those reported in previous works, which were dominated by surficial close contact interactions. Moreover, based on the experimentally obtained single-crystal structures, we explain that the luminescence of 1a follows the intraligand π*→π emission states or weak ligand to ligand charge transfer (LLCT), with little incorporation of intraligand charge transfer (ILCT).

Performance and exhaust emission characteristics of a CI engine fueled with diesel-nitrogenated additives

In present work the effects of nitromethane (NM) and nitroethane (NE) as nitrogenated additives on physical properties, combustion performance, and emission of diesel fuel, were studied. Nitrogenated additives have high oxygen content and are considered as oxygenated additives. These additives were blended with diesel fuel, in 1/9 volume ratio. The experimental study was carried out on ECE R-96 8-modes cycle. The result showed that the use of additives reduces viscosity but increases cetane index. In addition, nitrogenated additives increased brake thermal efficiency (BTE) while reduced certain exhaust emissions. Results of AVL SPC 472_MCE97 analysis showed that the addition of NE can reduce the overall smoke value by 44%. The smoke emission decreased at the maximum torque speed (1500rpm) rather than at the rated power speed (2200rpm).

ChemInform Abstract: Promotion of Henry Reactions Using Cu(OTf)2 and a Sterically Hindered Schiff Base: Access to Enantioenriched β‐Hydroxynitroalkanes.

AbstractThe reaction can also be conducted with nitroethane resulting in yields and enantioselectivities comparable to the reaction with nitromethane but only moderate diastereoselectivities.

The second crossover of a binary mixture with a high-molecular weight polymer

Based on the experimental data of Venkatesu [P. Venkatesu, J. Chem. Phys. 123, 024902-1 (2005)], we obtained the effective critical exponents of the mixtures of nitroethane (NE) + 3-methylpentane (MP) with three different polyethylene oxides (PEO, M w = 9 105) concentrations c = 0, 0.759 and 1.509 mg cc−1 by the spline fit. We observed that the critical behaviour of pure NE + MP is different from that of the mixtures NE + MP with PEO concentrations c = 0.759 and 1.509 mg cc−1. The mixtures NE + MP + PEO show the second crossovers from the mean-field behaviour to the Ising-like behaviour as the distance from the critical point increases, which may be attributed to the disturbing field of long-range indirect interactions between monomers of the PEO chain and polymer–solvent. It is consistent with the model of the critical behaviour of ‘real’ or ‘nonideal’ systems, which can explain the anomalous critical phenomena of some systems.

Effects of Methanogenic Inhibitors on Methane Production and Abundances of Methanogens and Cellulolytic Bacteria in In Vitro Ruminal Cultures

The objective of this study was to systematically evaluate and compare the effects of select antimethanogen compounds on methane production, feed digestion and fermentation, and populations of ruminal bacteria and methanogens using in vitro cultures. Seven compounds, including 2-bromoethanesulphonate (BES), propynoic acid (PA), nitroethane (NE), ethyl trans-2-butenoate (ETB), 2-nitroethanol (2NEOH), sodium nitrate (SN), and ethyl-2-butynote (EB), were tested at a final concentration of 12 mM. Ground alfalfa hay was included as the only substrate to simulate daily forage intake. Compared to no-inhibitor controls, PA, 2NEOH, and SN greatly reduced the production of methane (70 to 99%), volatile fatty acids (VFAs; 46 to 66%), acetate (30 to 60%), and propionate (79 to 82%), with 2NEOH reducing the most. EB reduced methane production by 23% without a significant effect on total VFAs, acetate, or propionate. BES significantly reduced the propionate concentration but not the production of methane, total VFAs, or acetate. ETB or NE had no significant effect on any of the above-mentioned measurements. Specific quantitative-PCR (qPCR) assays showed that none of the inhibitors significantly affected total bacterial populations but that they did reduce the Fibrobacter succinogenes population. SN reduced the Ruminococcus albus population, while PA and 2NEOH increased the populations of both R. albus and Ruminococcus flavefaciens. Archaeon-specific PCR-denaturing gradient gel electrophoresis (DGGE) showed that all the inhibitors affected the methanogen population structure, while archaeon-specific qPCR revealed a significant decrease in methanogen population in all treatments. These results showed that EB, ETB, NE, and BES can effectively reduce the total population of methanogens but that they reduce methane production to a lesser extent. The results may guide future in vivo studies to develop effective mitigation of methane emission from ruminants.

Reactions of the simple nitroalkanes with hydroxide ion in water. Evidence for a complex mechanism

Conventional kinetic analysis of the reactions of nitromethane (NM), nitroethane (NE) and 2-nitropropane (2-NP) with hydroxide ion in water revealed that the reactions are complex and involve kinetically significant intermediates. Kinetic experiments at the isosbestic points where changes in reactant and product absorbance cancel indicate the evolution and decay of absorbance characteristic of the formation of reactive intermediates. The deviations from 1st-order kinetics were observed to increase with increasing extent of reaction and in the reactant order: NM < NE < 2-NP. The apparent deuterium kinetic isotope effects for proton/deuteron transfer approach unity near zero time and increased with time toward plateau values as the reaction kinetics reach steady state. It is proposed that the initially formed preassociation complexes are transformed to more intimate reactant complexes which can give products by two possible pathways.

Photodissociation Dynamics of 2-Nitropropane and 2-Methyl-2-nitropropane at 248 and 193 nm

Dynamics of formation of electronically excited NO2 and formation of OH fragment, during photo dissociation of 2-nitropropane (NP) and 2-methyl-2-nitropropane (MNP), were investigated at 193 and 248 nm. The radiative lifetime of the electronically excited NO2 fragment, observed at 193 nm, was measured to be 1.2 ( 0.1 micros and the rate coefficient of quenching of its emission by MNP was measured as (2.7 ( 0.1) x 10(-10) molecule(-1) cm3 s(-1). Formation of the ground electronic state of OH was confirmed in both molecules. State selective laser induced fluorescence technique was used to detect the nascent OH (X 2Pi, v'', J'') fragments in different ro-vibrational states, and to obtain information on energy partitioning. Though MNP and NP differ in the types of the available H atoms, the dynamics of OH formation is found to be the same in both. The relative population in different rotational states does not follow Boltzmann equilibrium distribution in both the molecules at 193 and 248 nm. The translational energies of the OH fragments, calculated from the Doppler width, are 21.2 ( 7.2 and 25.0 ( 2.5 kcal mol-1 for NP at 248 and 193 nm, respectively. The translational energies of the OH fragments, in the case of MNP, are found to be lower, 17.5 ( 4.1 and 22.0 ( 3.2 kcal mol-1,respectively, at 248 nm 193 nm. These results are compared with the earlier reports on photodissociation of nitromethane (NM), nitroethane (NE), and other nitroalkanes. All possible dissociation pathways of these molecules--NM, NE, NP, and MNPs leading to the formation of the OH fragment were investigated computationally, with geometry optimization at the B3LYP/6-311+G(d,p) level and energy calculation at the MP4(SDQ)/6-311+G (d,p) level. The results suggest that in NM, OH is formed after isomerization to CH2N(OH)O, whereas in all other cases OH is formed from HONO, a primary product of molecular elimination of nitroalkanes, formed with sufficient internal energy.

Negative ions of nitroethane and its clusters

Valence and dipole-bound negative ions of the nitroethane (NE) molecule and its clusters are studied using photoelectron spectroscopy (PES), Rydberg electron transfer (RET) techniques, and ab initio methods. Valence adiabatic electron affinities (EA(a)s) of NE, C(2)H(5)NO(2), and its clusters, (C(2)H(5)NO(2))(n), n=2-5, are estimated using vibrationally unresolved PES to be 0.3+/-0.2 eV (n=1), 0.9+/-0.2 eV (n=2), 1.5+/-0.2 eV (n=3), 1.9+/-0.2 eV (n=4), and 2.1+/-0.2 eV (n=5). These energies were then used to determine stepwise anion-neutral solvation energies and compared with previous literature values. Vertical detachment energies for (C(2)H(5)NO(2))(n)(-) were also measured to be 0.92+/-0.10 eV (n=1), 1.63+/-0.10 eV (n=2), 2.04+/-0.10 eV (n=3), and 2.3+/-0.1 eV (n=4). RET experiments show that Rydberg electrons can be attached to NE both as dipole-bound and valence bound anion states. The results are similar to those found for nitromethane (NM), where it was argued that the diffuse dipole state act as a "doorway state" to the more tightly bound valence anion. Using previous models for relating the maximum in the RET dependence of the Rydberg effective principle number n(max)(*), the dipole-bound electron affinity is predicted to be approximately 25 meV. However, a close examination of the RET cross section data for NE and a re-examination of such data for NM finds a much broader dependence on n(*) than is seen for RET in conventional dipole bound states and, more importantly, a pronounced [l] dependence is found in n(max)(*) (n(max)(*) increases with [l]). Ab initio calculations agree well with the experimental results apart from the vertical electron affinity value associated with the dipole bound state which is predicted to be 8 meV. Moreover, the calculations help to visualize the dramatic difference in the distributions of the excess electron for dipole-bound and valence states, and suggest that NE clusters form only anions where the excess electron localizes on a single monomer.

Effects of select nitrocompounds on in vitro ruminal fermentation during conditions of limiting or excess added reductant

Ruminal methane (CH 4) production results in the loss of up to 12% of gross energy intake and contributes nearly 20% of the United States’ annual emission of this greenhouse gas. We report the effects of select nitrocompounds on ruminal fermentation after 22 h in vitro incubation (39 °C) with or without additions of hydrogen (H 2), formate or both. In incubations containing no added reductant, CH 4 production was inhibited 41% by 2-nitro-1-propanol (2NPOH) and >97% by 3-nitro-1-propionic acid (3NPA), nitroethane (NE) and 2-nitroethanol (2NEOH) compared to non-treated controls and H 2 did not accumulate. With formate as the sole added reductant, nitro-treatment reduced CH 4 production by >99% and caused 42% to complete inhibition of formate catabolism compared to controls, and the accumulation of H 2 increased slightly. Nitro-treatment decreased CH 4 production 57–98% from that of controls when supplied H 2 or formate plus H 2. Formate catabolism was decreased 42–84% from that in controls by all nitro-treatments except 3NPA with both formate and H 2. Greater than 97% of the added H 2 was catabolized within controls; >84% was catabolized in nitro-treated incubations. Acetate, propionate and butyrate accumulations were unaffected by nitro-treatment irregardless of reductant; however, effects on ammonia and branched chain fatty acid accumulations varied. These results suggest that nitro-treatment inhibited formate dehydrogenase/formate hydrogen lyase and hydrogenase activity.

Electrochemical synthesis of 2,2-dinitropropanol

This paper describes electrochemical approaches to the synthesis of 2,2-dinitropropanol (DNPOH) and discusses the potential for pilot-plant scale synthesis. In this work, the anode of the electrochemical cell replaces the chemical oxidants used in the conventional synthesis for the purpose of reducing secondary waste and the consequent disposal cost. The electrosynthesis reactions described in this work use the common starting material, nitroethane (NE). The synthesis of the end-product DNPOH involves two steps: (1) electrochemical oxidative nitration (addition of a geminal NO2 group); and, (2) condensation with formaldehyde. Electrochemical oxidation of NE was first attempted by direct oxidation on a Pt electrode surface resulting in low yield and significant generation of undesirable by-product. Alternatively, two different mediators were employed resulting in a dramatic improvement of yield for the oxidative nitration step. The two different mediators used, Ag+/Ag0 and Fe(CN)6−3/−4, were derived from the chemical oxidants known to perform the oxidative nitration. The Fe(CN)6−3/−4 mediator demonstrated the best promise for scale-up and industrial production due to the lower cost of the mediator and the solubility of the mediator lending it to greater ease-of-use in conventional electrochemical cell designs.

Inhibitory Effect of Select Nitrocompounds on Growth and Survivability of Listeria monocytogenes In Vitro

We report the effects of 2-nitro-1-propanol (2NPOH), 2-nitroethanol (2NEOH), and nitroethane (NE) on growth and survivability of Listeria monocytogenes. In all cases, inhibition was greatest with 2NPOH and least with NE. For example, specific growth rates of L. monocytogenes strain 18 declined (P < 0.05) 76, 60, and 29% from controls during aerobic culture at 37°C in brain heart infusion broth containing 10mM 2NPOH, 2NEOH, or NE, respectively. Mean specific growth rate for the controls incubated likewise without added nitrocompound was 0.62±0.02 h−1. Specific growth rates of L. monocytogenes Scott A decreased (P < 0.05) 67, 45, and 11%, respectively, from controls (0.67±0.02 h−1) when cultured similarly. Specific growth rates for L. monocytogenes strain 18 incubated similarly except at 30°C were reduced (P < 0.05) 76, 60, and 30%, respectively, and were reduced (P < 0.05) 78, 23, and 23% during anaerobic culture at 30°C in brain heart infusion broth containing 15mM 2NPOH, 2NEOH, or NE (control rates ranged from 0.37±0.07 to 0.74±0.05 h−1). Survivability of L. monocytogenes strain 18 was reduced (P < 0.05) during aerobic storage (4 months at 4°C) in brain heart infusion broth containing 2NPOH or 2NEOH (by 7.8 and 1.9 log units, respectively) but not NE. The inhibitory effect of 2NPOH was approximately 20% greater during growth at pH 7.0 than at pH 5.6 or 8.0. These results demonstrate the differential inhibitory activity of 2NPOH, 2NEOH, and NE against L. monocytogenes in vitro.

Effects of nitrocompounds and feedstuffs on in vitro methane production in chicken cecal contents and rumen fluid

Short-chain volatile fatty acids (VFA) and methane are the products from a wide variety of microorganisms living in the gastrointestinal tract. The objective of this study was to examine effects of feedstuff and select nitrocompounds on VFA and methane production during in vitro incubation of laying hen cecal contents and rumen fluid from cattle and sheep. In the first experiment, one of the three nitrocompound was added to incubations containing cecal contents from laying hens supplemented with either alfalfa (AF) or layer feed (LF). Both feed material influenced VFA production and acetic acid was the primary component. Incubations with nitroethanol and 2-nitropropanol (NP) had significantly ( P < 0.0 5 ) higher propionate concentrations than incubations with added nitroethane (NE). The results further indicated that incubations containing LF produced significantly ( P < 0.0 5 ) more butyrate than incubations with added AF. Addition of NP and LF to incubations of avian cecal flora may promote Gram-positive, saccharolytic, VFA-producing bacteria, especially Clostridium spp. which is the predominant group in ceca. Similar to VFA production, both feed materials fostered methane production in the incubations although methane was lower ( P < 0.0 5 ) in incubations with added nitrocompound, particularly NE. In experiments 3–8, NE was examined in incubations of bovine or ovine rumen fluid or cecal contents containing either AF or LF. Unlike cecal contents, LF significantly ( P < 0.0 5 ) supported in vitro methane production in incubations of both rumen fluids. The results show that NE impedes methane production, especially in incubations of chicken cecal contents.

Effect of polymer chain in coexisting liquid phases by refractive index measurements

The behavior of polyethylene oxide (PEO, molecular weight, M(w) = 9 x 10(5), as an impurity) was studied in the critical binary mixture of nitroethane (NE) + 3-methylpentane (MP) by refractive index measurements. The measurements were performed at three different PEO concentrations (C = 0.373, 0.759, and 1.509 mg/cc) in the near critical composition of NEMP. We observed that the coexisting phase region shifts down with increasing PEO concentration and the critical temperature (T(c)) decreases linearly with C. At temperatures T close enough to T(c), the critical exponent beta [defined by the relation (n1-n2) proportional (T(c)-T)beta, with n1 and n2 being the refractive indices of the coexisting phases] was found to decrease from 0.456 to 0.372 when the PEO concentration changes from 0.373 to 1.509 mg/cc. These values are higher than that of 0.345+/-0.015 of pure NEMP, which is compatible with the three-dimensional Ising value beta = 0.325. It appears that the shape of the PEO in NEMP coexistence curves is similar from that of pure NE + MP.