Reaction Threshold Research Articles

Convenient Location of a Near-Threshold Proton-Emitting Resonance in ^{11}B.

The presence of clusterlike narrow resonances in the vicinity of reaction or decay thresholds is a ubiquitous phenomenon with profound consequences. We argue that the continuum coupling, present in the open quantum system description of the atomic nucleus, can profoundly impact the nature of near-threshold states. In this Letter, we discuss the structure of the recently observed near-threshold resonance in ^{11}B, whose very existence explains the puzzling beta-delayed proton emission of the neutron-rich ^{11}Be.

Microcanonical Rate Constants for Unimolecular Reactions in the Low-Pressure Limit.

Low-pressure-limit microcanonical rate constants, κ0(E,J), describe the rate of activating bath gas collisions in a unimolecular reaction and are calculated here using classical trajectories and quantized thresholds for reaction. The resulting semiclassical rate constants are two-dimensional (in total energy E and total angular momentum J) and are intermediate in complexity between the four-dimensional state-to-state collisional energy and angular momentum transfer rate constant, R(E',J';E,J), and the highly averaged thermal rate constant, k0. Results are presented for CH4 (+M), C2Hx (+M), x = 3-6, and H2O (+M), where κ0(E,J) is shown generally to be a sensitive function of the bath gas, temperature, and initial state of the unimolecular reactant. Strong variations in κ0 with respect to E and J lead to complex trends in relative microcanonical bath gas efficiencies. This underlying complexity may complicate the search for simple explanations for observed trends in relative thermal bath gas efficiencies. A different measure of the microcanonical collision efficiency that describes the energy range of activating collisions is introduced that supports the empirical decomposition of collisional activation into separable translational-to-vibrational and rotational-to-vibrational activation mechanisms. The two mechanisms depend differently on mass, temperature, and the J-dependence of the threshold energy for reaction, with rotational-to-vibrational activation favored for heavier baths and for reactions with rigid transition states. Finally, κ0 is used to test the accuracy of several two-dimensional models for R that were proposed for use in master equation studies.

Diagnostic value of ABR wave and DPOAE test in 65 infants with secretory otitis media

Objective To study and analyze the diagnostic value of auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) in infants with secretory otitis media. Methods From June 2016 to June 2018, 65 infants (120 ears) with secretory otitis media who were treated at the First People's Hospital of Taizhou were selected.All the 120 ears were diagnosed by ABR wave test and DPOAE test machine.The results of different diagnostic methods were observed and compared. Results Among 65 cases (120 ears), 60 ears (50.00%) with mildly abnormality, 43 ears (35.83%) with moderate abnormality and 17 ears (14.17%) with normal ABR wave Ⅴ response threshold.There was no statistically significant difference in Ⅰ-Ⅴ wave interval between the mild abnormal group and the normal group (P>0.05), but Ⅰ-Ⅴ wave interval in the moderate abnormal group[(4.27±0.27)ms in moderate abnormal group] was significantly shorter than that in the normal group[(4.75±0.31)ms] and the mild abnormal group[(4.73±0.21)ms], the differences were statistically significant(t=5.949, 9.722, all P<0.05). The Ⅴ response threshold of bone-guided ABR wave was normal in 108 ears(90.00%, 108/120). The Ⅴ latency of bone guided wave was (8.16±0.22)ms, and abnormal in 12 ears (10.00%, 12/120). With the increase of the gas conduction reaction threshold, the bone conduction ABR reaction threshold also increased, but it was not as obvious as the air conduction.The wave Ⅴ latency in the normal BRT group was significantly lower than that in the abnormal group (compared with mild abnormal group, t=17.400, P<0.05; compared with moderate abnormal group, t=130.015, P<0.05). DPOAE test failed 86 ears (71.67%, 86/120), passed through 34 ears (28.33%, 34/120). Conclusion The latency of ABR wave I is sensitive to the diagnosis of secretory otitis media in infants.The combination of DPOAE and ABR is helpful to the early diagnosis of the disease.ABR and DPOAE tests have high value and are worthy of popularizing in clinic. Key words: Otitis media; Evoked potentials, auditory, brain stem; Distortion product otoacoustic emissions; Air-guided ABR waves; Bone-guided ABR waves; Wave I latency

Research and Selection of Prospective Materials for Activation Dosimetry of Intense Bremsstrahlung Radiation

Radiation technologies based on the use of powerful electron beams and gamma radiation are closely related to the need for dosimetry of these beams. Dosimetry based on the use of the inelastic gamma-ray scattering reaction on a number of nuclei with the formation of isomers with different half-lives and energies of radiation quanta is very successful for these purposes. An example of this application in dosimetry is the 115In (γ,γ')115mIn reaction, which results in the formation of the 115mIn isomer, having a gamma line with an energy of 336.24 keV and a half-life of 4.5 hours. There was a successful application of this technique in dosimetry in solving certain practical problems (irradiation complexes based on 60Co source- cobalt “guns”). In this work, it is shown that the use of In detectors for dosimetry of gamma-radiation with a wide energy spectrum (bremsstrahlung) is associated with significant uncertainty in measuring the equivalent dose of the gamma spectrum with an upper limit of 10 MeV. This uncertainty is due to the relatively high threshold of the aforementioned reaction of 1.08 MeV. The quantitative contribution to the total radiation flux of the region of the gamma spectrum below the threshold (γ,γ') of the reaction on the In nucleus was determined and it was shown that, depending on the direction of radiation, there is an systematic error in measuring the equivalent dose, reaching 20-60%. Investigated and proposed for use alternative materials detectors, allowing reducing the systematic error in measuring the equivalent dose to 2-3%, which is quite acceptable for practical use.

SCALP: a detector for (n,α) cross-section measurements

Neutron induced reactions on oxygen have been studied with strong interest because of the uncertainties generated on the helium production in fuel and on the neutron multiplication factor in nuclear reactors [1], [2]. Still large discrepancies exist and new measurements are welcome in order to acquire new data aiming at the uncertainty reduction [3]. SCALP (Scintillating ionization Chamber for ALPha particle production in neutron induced reaction) is a new scintillating ionization chamber [4] used as an active target to measure the cross section of (n, alpha) reactions on various gaseous targets such as 19F or 16O, from the reaction threshold up to 15 MeV. It consists of an ionization chamber filled with CF4 (for fluorine measurements) or CF4+CO2(for oxygen measurements) allowing the detection of the energy deposed by the light charged particles emitted in the (n, alpha) reaction. In addition, four Photo- Multiplier Tubes detect the scintillation light produced by the interaction of the particles in the gas active volume. Taking advantage of the fast response of the scintillation, the neutron kinetic energy can be inferred by time-of-flight measurements. SCALP is then well adapted to mono-energetic neutron beams or to white neutron beams that will be delivered at the NFS Facility [5]. Because of its good resolution, SCALP discriminates different channel outputs, enabling to disentangle the different reactions [6]. We will present the performances of the SCALP detector in terms of temporal and energetic features. We will also present tests made at the GENESIS plate-form at the LPSC Grenoble [7].

Measurement of the energy-differential cross-section of the 12C(n,p)12B and 12C(n,d)11B reactions at the n_TOF facility at CERN

Although the 12C(n,p)12B and 12C(n,d)11B reactions are of interest in several fields of basic and applied Nuclear Physics the present knowledge of these two cross-sections is far from being accurate and reliable, with both evaluations and data showing sizable discrepancies. As part of the challenging n_TOF program on (n,cp) nuclear reactions study, the energy differential cross-sections of the 12C(n,p)12B and 12C(n,d)11 B reactions have been measured at CERN from the reaction thresholds up to 30 MeV neutron energy. Both measurements have been recently performed at the long flight-path (185 m) experimental area of the n_TOF facility at CERN using a pure (99.95%) rigid graphite target and two silicon telescopes. In this paper an overview of the experiment is presented together with a few preliminary results.

Wave packet quantum dynamics of &lt;inline-formula&gt;&lt;tex-math id="Z-20200417045027-1"&gt;\begin{document}${\bf{C}}{(^3}{\bf{P}}) + {{\bf{H}}_2}({{\bf{X}}^1} \Sigma _{\bf{g}}^ + ) $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_Z-20200417045027-1.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_Z-20200417045027-1.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; &lt;inline-formula&gt;&lt;tex-math id="Z-20200418100246-1"&gt;\begin{document}$ \to {\bf{H}}{(^2}{\bf{S}}) + {\bf{CH}}{(^2} \Pi ) $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_Z-20200418100246-1.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_Z-20200418100246-1.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; reaction based on new CH&lt;sub&gt;2&lt;/sub&gt;(&lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}${\tilde {\bf X}{}^3}\bf A''$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M2.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M2.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;) surface

The C(&lt;sup&gt;3&lt;/sup&gt;P) + H&lt;sub&gt;2 &lt;/sub&gt;→ CH+H reaction in a collision energy range of 1.0–2.0 eV with the initial state &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}$\nu = 0{\rm{ }},j = 0$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M6.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M6.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; is investigated based on the new potential energy surface (PES) by using the Chebyshev wave packet method. All partial wave contributions up to &lt;i&gt;J&lt;/i&gt; = 60 are calculated explicitly by the coupled state (CS) approximation method and the Coriolis coupling (CC) effect. Dynamic properties such as reaction probabilities, integral cross sections, and state specific rate constants are calculated. The calculated probabilities and integral reaction cross sections display an increasing trend with the increase of the collision energy and an oscillatory structure due to the CH&lt;sub&gt;2&lt;/sub&gt; well on the reaction path. The thermal rate constants of the endoergic reaction with a temperature ranging from 1000 K to 2000 K are obtained also. The calculated rate constants increase in the entire temperature range, showing a sharp &lt;i&gt;T&lt;/i&gt; dependence in a range of 1400–2000 K. The rate constants are sensitive to the temperature due to the high threshold of the title reaction. In addition, the results of the exact calculations including CC effect are compared with those from the CS approximation. For smaller &lt;i&gt;J&lt;/i&gt;, the CS probabilities are larger than the CC results, while for larger &lt;i&gt;J&lt;/i&gt;, they are smaller than the CC ones. For reaction cross sections and rate constants, the CS results and the CC ones are in good agreement with each other at lower energy. However, they turn different at higher energy. The comparison between the CC and CS results indicates that neglecting the Coriolis coupling leads the cross sections and the rate constants to be underestimated due to the formation of a CH&lt;sub&gt;2&lt;/sub&gt; complex supported by stationary point of CH&lt;sub&gt;2&lt;/sub&gt;(&lt;inline-formula&gt;&lt;tex-math id="M7"&gt;\begin{document}${\tilde{\rm X}}{}^3 \rm A''$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M7.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="8-20200132_M7.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;) PES. It is suggested that the CH&lt;sub&gt;2&lt;/sub&gt; complex plays an important role in the process of the title reaction. However, it seems to overestimate the CS and CC rate constants because the barrier recrossing is neglected. Unfortunately, the results obtained in the present work have no corresponding theoretical or experimental data to be compared with, therefore these results provide simply a certain reference significance to the follow-up study of the title reaction.

Geroprotective effects of ethylmethylhydroxypyridine succinate in an experimental study

To study an effect of mexidol on the life expectancy, weight, seizure response thresholds, and impaired cognitive and motor functions during aging in male Wistar rats. In a long-term experiment, male Wistar rats, aged 3-26 months, were assessed for impaired cognitive functions (passive avoidance conditioned reflex test), convulsive threshold (test with pentylenetetrazole), motor deficits (tests of rotating rod and pulling on the crossbar), and life expectancy. The rats received mexidol in the form of 0,15% solution, which replaced drinking water, during two 2 month courses at the age of 18-20 and 22-24 month. A dose of mexidol consumed by the rat was 40-75 mg/kg/day. In old male Wistar rats, the long-term treatment with mexidol increases the life expectancy, improves learning, preservation and reproduction of the memory trace in the passive avoidance conditioned reflex test, increases the convulsive threshold and improves muscle tone and coordination of movements that are impaired during aging. Mexidol increases the threshold of convulsive reaction, restores cognitive and neurological deficits that occur during aging in male Wistar rats and increases the by its ability to influence mitochondriogenesis and antioxidant properties.

Development of neutron activation system on EAST.

A neutron activation system (NAS) has been developed on the Experimental Advanced Superconducting Tokamak (EAST) for the investigation of time-integrated neutron yield. It is a robust neutron diagnostic with high precision and a wide dynamic range. Some high purity materials with a proper nuclear reaction energy threshold and cross section are tested as neutron detectors in the NAS, and they are delivered to the tokamak device by a pneumatic transfer system. The length of the pneumatic pipeline is about 50 m, and the transfer time ranges from 10 s to 20 s. The decay gamma rays of the activated samples are measured with a high-purity germanium spectrometer, and its detection efficiencies are 6.9% at 336 keV and 1.7% at 1779 keV, respectively. Indium and silicon samples with a reaction threshold of 0.3 MeV and 4.0 MeV, respectively, were successfully implemented in the diagnosis of DD and DT neutron yield in the EAST. The neutron flux of the NAS was compared with the count of the fission chamber in the EAST neutral beam injection experiment, and the DD neutron yield evaluated by the NAS ranges from 1.9 × 1012 n/shot to 5.9 × 1014 n/shot during recent experimental campaign.

Integral measurement of spectrum-averaged cross sections of a few threshold reactions induced by fast neutrons of a TRIGA reactor: comparison with integrated data from excitation functions given in various data libraries

Abstract Integral cross sections of the reactions 24Mg(n,p)24Na, 27Al(n,p)27Mg, 27Al(n,α)24Na, 58Ni(n,d + np)57Co and 60Ni(n,p)60Co were measured for the first time using the fast neutron spectrum of a TRIGA reactor extending from 0.5 to 20 MeV. The values obtained in this work were comparable with the recommended values for a pure 235U prompt fission spectrum. The measured integral value was utilized for integral test of excitation function of each reaction given in some data libraries, namely ENDF/B-VIII.0, TENDL-2017, IRDFF-1.05 and ROSFOND-2010. The integral measurements are generally consistent with the integrated values within 5 %, except for a few cases, e. g. the reaction 60Ni(n,p)60Co, where the data libraries appear to need improvement.

Cross section of α -induced reactions on Au197 at sub-Coulomb energies

Statistical model calculations have to be used for the determination of reaction rates in large-scale reaction networks for heavy-element nucleosynthesis. A basic ingredient of such a calculation is the a-nucleus optical model potential. Several different parameter sets are available in literature, but their predictions of a-induced reaction rates vary widely, sometimes even exceeding one order of magnitude. This paper presents the result of a-induced reaction cross-section measurements on gold which could be carried out for the first time very close to the astrophysically relevant energy region. The new experimental data are used to test statistical model predictions and to constrain the a-nucleus optical model potential. For the measurements the activation technique was used. The cross section of the (a,n) and (a,2n) reactions was determined from g-ray counting, while that of the radiative capture was determined via X-ray counting. The cross section of the reactions was measured below E$_a=20.0$~MeV. In the case of the $^{197}$Au(a,2n)$^{199}$Tl reaction down to 17.5~MeV with 0.5-MeV steps, reaching closer to the reaction threshold than ever before. The cross section of $^{197}$Au(a,n)$^{200}$Tl and $^{197}$Au(a,g)$^{201}$Tl was measured down to E$_a=13.6$ and 14.0~MeV, respectively, with 0.5-MeV steps above the (a,2n) reaction threshold and with 1.0-MeV steps below that. The new dataset is in agreement with the available values from the literature, but is more precise and extends towards lower energies. Two orders of magnitude lower cross sections were successfully measured than in previous experiments which used g-ray counting only, thus providing experimental data at lower energies than ever before. The new precision dataset allows us to find the best-fit a-nucleus optical model potential and to predict cross sections in the Gamow window with smaller uncertainties.

Identifying and managing patients at risk of severe allergic reactions to food: Report from two iFAAM workshops.

Food allergy affects a small but important number of children and adults. Much of the morbidity associated with food allergy is driven by the fear of a severe reaction and fatalities continue to occur. Foods are the commonest cause of anaphylaxis. One of the aims of the European Union-funded Integrated Approaches to Food Allergen and Allergy Risk Management (iFAAM) project was to improve the identification and management of children and adults at risk of experiencing a severe reaction. A number of interconnected studies within the project have focused on quantifying the severity of allergic reactions; the impact of food matrix, immunological factors on severity of reactions; the impact of co-factors such as medications on the severity of reactions; utilizing single-dose challenges to understand threshold and severity of reactions; and community studies to understand the experience of patients suffering real-life allergic reactions to food. Associated studies have examined population thresholds and co-factors such as exercise and stress. This paper summarizes two workshops focused on the severity of allergic reactions to food. It outlines the related studies being undertaken in the project indicating how they are likely to impact on our ability to identify individuals at risk of severe reactions and improve their management.

ON MECHANISMS OF OXYGEN INFLUENCE ON GAS-PHASE PARAMETERS AND SILICON REACTIVE-ION ETCHING KINETICS IN HBr + Cl2 + O2 PLASMA

The effects of both HBr/O2 and Cl2/O2 mixing ratios in HBr+Cl2+O2 gas mixture on plasma parameters, steady-state densities of active species and Si etching kinetics were studied under the typical conditions of reactive ion etching process: total gas pressure (p = 10 mTorr), input power (W = 500 W), bias power (Wdc = 200 W). The data on internal plasma parameters and plasma chemistry were obtained using a combination of Langmuir probe diagnostics and 0-dimensional (global) plasma modeling. It was found that the variation in HBr/O2 mixing ratio at constant Cl2 fraction in a feed gas is characterized by the stronger impact on the steady-state plasma composition through both electron-impact and atom-molecular reaction kinetics as well as allows one to obtain the wider change in the total halogen atom density. It was shown that changes in both HBr/O2 and Cl2/O2 mixing ratios toward O2-rich plasmas lowers the Si etching rate that exhibits no evident correlations with total halogen atom flux and ion energy flux. The model-based analysis of Si etching kinetics allowed one to conclude that the effective reaction probability for Si + Cl/Br heterogeneous reaction depends on the flux of oxidative species – oxygen atoms and OH radicals. The reasons may be 1) the oxidation of silicon resulting in higher reaction threshold energy; and 2) the decreasing fraction of free adsorption sites for Cl/Br atoms due to the oxidation of reaction products into the lower volatile SiBrxOy and SiClxOy compounds.

Validation of IRDFF-II library by means of 252Cf spectral averaged cross sections

Spectrum-averaged cross sections (SACS) is an important quantity usable in validation of nuclear cross sections. Especially in case of dosimetrical reactions there is a request on precise validation. This paper presents SACS measured in the reference 252Cf(sf) neutron field for neutron dosimetry reactions to validate recently updated IRDFF-II library intended mainly for neutron metrology applications. It covers 46Ti(n,p)46Sc, 47Ti(n,p)47Sc, 48Ti(n,p)48Sc, 58Ni(n,p)58Co, 60Ni(n,p)60Co, 58Ni(n,2n)57Ni, 24Mg(n,p)24Na, 27Al(n,α)24Na and 63Cu(n,α)60Co threshold reactions. Measurement of 60Ni(n,p)60Co SACS is included in NEA's High Priority Nuclear Data Request List since existing data are discrepant. Spectral averaged cross sections were derived from experimentally determined reaction rates by gamma spectrometry using a same high-purity germanium detector to measure all irradiated samples. Measured spectrum-averaged cross sections agree very well within quoted uncertainties with those calculated using the IRDFF-II library. No other library achieves such good performance. Thus, the presented data support use of the cross sections of the mentioned reactions from IRDFF-II library.

From Molecules to Carbon Materials—High Pressure Induced Polymerization and Bonding Mechanisms of Unsaturated Compounds

With the development of high-pressure apparatus, in situ characterization methods and theoretical calculations, high-pressure technology becomes a more and more important method to synthesize new compounds with unusual structures and properties. By compressing compounds containing unsaturated carbon atoms, novel poly-ionic polymers, graphanes and carbon nanothreads were obtained. Their compositions and structures were carefully studied by combining multiple cutting-edge technologies, like the in situ high-pressure X-ray and neutron diffraction, transmission electron microscopy, pair distribution function, solid-state nuclear magnetic resonance and gas chromatography-mass spectroscopy. The reaction mechanisms were investigated based on the crystal structure at the reaction threshold pressure (the pressure just before the reaction taking place), the long-range and short-range structure of the product, molecular structure of the intermediates, as well as the theoretical calculation. In this review, we will summarize the synthesis of carbon materials by compressing the unsaturated compounds and its reaction characteristics under extreme conditions. The topochemical reaction mechanism and related characterization methods of the molecular system will be highlighted. This review will provide a reference for designing chemical reaction and exploring novel carbon materials under high-pressure condition.

Allergen-Specific Immunotherapy for Immunoglobulin E-Mediated Food Allergy

Food allergy is a potentially life-threatening condition and a significant public health concern worldwide. The current management includes food avoidance and use of emergency medications. The growing prevalence of food allergy drives research towards specific allergen immunotherapy (AIT), which represents a potential disease-modifying approach. AIT consists of the progressive administration of amounts of the offending allergen in order to induce food desensitisation, creating an increase in reaction threshold with regular exposure to the allergen. AIT can be performed through oral, sublingual, epicutaneous, and subcutaneous routes. The target is to achieve post desensitisation effectiveness: a long-lasting condition allowing patients to introduce food without reactions, even after a period of discontinuation of the offending food.

Oral immunotherapy for multiple foods in a pediatric allergy clinic setting

BackgroundThe increasing incidence of pediatric food allergy results in significant health care burden and family stress. Oral immunotherapy (OIT) can induce tolerance to peanut, milk, and egg. OIT for other foods, particularly multiple foods simultaneously, has not been thoroughly studied. ObjectiveTo summarize our experience with OIT for multiple foods in a pediatric allergy clinic setting. MethodsMedical records were reviewed for patients undergoing OIT for multiple foods. Methods and outcomes of OIT were summarized. Outcomes were analyzed for correlation with baseline food allergen skin prick tests (SPTs) and specific IgE (sIgE) test results. ResultsForty-five patients aged 1.5 to 18 years undertook OIT for up to 12 foods, including peanut, tree nuts, seeds, legumes, and egg. At the time of review, 35 patients were receiving daily maintenance dosing, 4 had completed OIT and were continuing to eat their foods 3 times weekly, and 6 had stopped OIT because of anxiety, inconvenience, or allergy symptoms. A total of 49% of patients had reactions during the up-dosing process, mostly oral itching (33%), perioral hives (40%), and abdominal pain (35%). There was no correlation of baseline skin prick test (SPT) and sIgE test results with reaction threshold for baseline food challenge, lowest dose causing reactions during up-dosing, or time to reach maintenance. Higher baseline sIgE level but not baseline SPT result was associated with an increased number of allergic reactions during OIT. Baseline SPT correlated with stopping OIT. ConclusionA similar approach to that used for peanut OIT can be taken for nonpeanut foods and for multiple foods simultaneously. High baseline allergy test results are not a contraindication to OIT.

Dissociative Electron Attachment to Molecular Acetonitrile.

Low-energy dissociative electron attachment to molecular acetonitrile (CH3CN) is investigated by recording the efficiency curves of CH2CN-, CHCN-, and CN- products, but the present curves are distinctly different from those in the previous reports. Now it is recommended that the reaction thresholds of e- + CH3CN → H2 + CHCN- and CH3 + CN- are respectively about 1.51 and 1.52 eV, and four shape-resonant states, one 2Π and three 2∑, of CH3CN- are involved in the fragmentations at the low and high electron-attachment energies. By using a high-resolution anion velocity-map imaging spectrometer, we obtain the CN- momentum images at the electron attachment energies of 7.10, 7.60, and 8.10 eV and interpret them with four pathways concerning two- and three-body dissociations.

ASSOCIATION OF EXPRESSION OF NFKB1, HIF1, VEGFA, VEGFВ, BAX, BCL2 GENES WITH BIOCHEMICAL REMEDIATION IN PATIENTS WITH LOCALIZED PROSTATE CANCER

Aim. To identify the association of NFKB1, HIF1, VEGFA, VEGFB, BAX, BCL2 gene expression in prostate adenocarcinoma cells with biochemical recurrence of localized prostate cancer. Patients and methods. Three groups of patients were formed in the study – the main one, the comparison group and the control group. In patients with prostate cancer (PC) in the main group (n = 56) with biochemical recurrence (BR) for two years after radical surgery, as well as in 60 patients without BR (experimental group) by real-time PCR in prostate cancer tissue the expression of genes NFKB1, HIF1, VEGFA, VEGFВ, BAX, BCL2 was determined. The control group consisted of 55 patients in whom, when performing diagnostic punctures for benign prostate tumors, biopsy specimens were taken in healthy tissues. The age of patients in the three groups ranged from 57 to 74 years (median 63 years). When quantifying expression of genes NFKB1, HIF1, VEGFA, VEGFВ, BAX, BCL2, the difference in the values of reaction threshold cycles (Ct) fixed for the studied and reference genes was determined. The relative level (Expr) was the ratio of Ct medians for each gene in two compared groups of the studied three ones: in the main group to the indicator in the control group, in the experimental group to the indicator in the control group, and also between the main group and the experimental group. Results. A comparative analysis of gene expression in prostate cancer tissue in the main group compared with the experimental group showed a statistically significant increase (p &lt; 0,05) in the relative index for the HIF1 gene (2,7 times), the VEGFA gene (2,4 times ) and the NFKB1 gene (2 times). Consequently, in patients with localized early recurrence prostate cancer, initially in the prostate tissue, a higher level of expression of the NFKB1, HIF1 and VEGFA genes was established. In the experimental group relative to the control group, the expression of the proapoptic gene BAX was 1,6 times higher (p &lt; 0,05), and for the antiapoptic gene BCL2 no changes were detected (p = 0,09). Thus, in patients with localized prostate cancer in the absence of BR, after radical prostatectomy, an initial increase in the expression of the BAX gene promoted the activation of apoptosis. In patients with localized prostate cancer, subsequent biochemical recurrence initially in the tissue of prostate adenocarcinoma inhibition of apoptosis due to increased expression of the BCL2 gene was observed. Conclusion. Enhancement of NFKB1, VEGFA, HIF1 and BCL2 gene expression in prostate tissue is associated with the development of BR in patients with localized prostate cancer.

Quantum Dynamics of Dissociative Chemisorption of H2 on the Stepped Cu(211) Surface

Reactions on stepped surfaces are relevant to heterogeneous catalysis, in which a reaction often takes place at the edges of nanoparticles where the edges resemble steps on single-crystal stepped surfaces. Previous results on H2 + Cu(211) showed that, in this system, steps do not enhance the reactivity and raised the question of whether this effect could be, in any way, related to the neglect of quantum dynamical effects in the theory. To investigate this, we present full quantum dynamical molecular beam simulations of sticking of H2 on Cu(211), in which all important rovibrational states populated in a molecular beam experiment are taken into account. We find that the reaction of H2 with Cu(211) is very well described with quasi-classical dynamics when simulating molecular beam sticking experiments, in which averaging takes place over a large number of rovibrational states and over translational energy distributions. Our results show that the stepped Cu(211) surface is distinct from its component Cu(111) terraces and Cu(100) steps and cannot be described as a combination of its component parts with respect to the reaction dynamics when considering the orientational dependence. Specifically, we present evidence that, at translational energies close to the reaction threshold, vibrationally excited molecules show a negative rotational quadrupole alignment parameter on Cu(211), which is not found on Cu(111) and Cu(100). The effect arises because these molecules react with a site-specific reaction mechanism at the step, that is, inelastic rotational enhancement, which is only effective for molecules with a small absolute value of the magnetic rotation quantum number. From a comparison to recent associative desorption experiments as well as Born–Oppenheimer molecular dynamics calculations, it follows that the effects of surface atom motion and electron–hole pair excitation on the reactivity fall within chemical accuracy, that is, modeling these effect shifts extracted reaction probability curves by less than 1 kcal/mol translational energy. We found no evidence in our fully state-resolved calculations for the “slow” reaction channel that was recently reported for associative desorption of H2 from Cu(111) and Cu(211), but our results for the fast channel are in good agreement with the experiments on H2 + Cu(211).