Search for a New B-L Z

A search for a new Z^{'} gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×10^{11} electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive new constraints on the Z^{'}-e coupling strength, which, for the mass range 0.3≲m_{Z^{'}}≲100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.

Constraints on New Physics in Electron g-2 from a Search for Invisible Decays of a Scalar, Pseudoscalar, Vector, and Axial Vector.

We performed a search for a new generic X boson, which could be a scalar (S), pseudoscalar (P), vector (V), or an axial vector (A) particle produced in the 100 GeV electron scattering off nuclei, e^{-}Z→e^{-}ZX, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such a process was found in the full NA64 dataset of 2.84×10^{11} electrons on target. We place new bounds on the S, P, V, A coupling strengths to electrons, and set constraints on their contributions to the electron anomalous magnetic moment a_{e}, |Δa_{X}|≲10^{-15}-10^{-13} for the X mass region 1 MeV≲m_{X}≲1 GeV. These results are an order of magnitude more sensitive compared to the current accuracy on a_{e} from the electron g-2 experiments and recent high-precision determination of the fine structure constant.

Triangle Singularity as the Origin of the a_{1}(1420).

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f_{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

Search for Axionlike and Scalar Particles with the NA64 Experiment.

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as a shield, and would be observed either through their a(s)→γγ decay in the rest of the HCAL detector, or as events with a large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing of the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to 2.84×10^{11} electrons on target, allowing us to set new limits on the a(s)γγ-coupling strength for a(s) masses below 55 MeV.

Dark Matter Search in Missing Energy Events with NA64.

A search for sub-GeV dark matter production mediated by a new vector boson A^{'}, called a dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with 2.84×10^{11} electrons on target no evidence of such a process has been found. The most stringent constraints on the A^{'} mixing strength with photons and the parameter space for the scalar and fermionic dark matter in the mass range ≲0.2 GeV are derived, thus demonstrating the power of the active beam dump approach for the dark matter search.

Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN.

We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e^{+}e^{-} pairs observed in the excited ^{8}Be^{*} nucleus decays. Because of its coupling to electrons, the X could be produced in the bremsstrahlung reaction e^{-}Z→e^{-}ZX by a 100 GeV e^{-} beam incident on an active target in the NA64 experiment at the CERN Super Proton Synchrotron and observed through the subsequent decay into a e^{+}e^{-} pair. With 5.4×10^{10} electrons on target, no evidence for such decays was found, allowing us to set first limits on the X-e^{-} coupling in the range 1.3×10^{-4}≲ε_{e}≲4.2×10^{-4} excluding part of the allowed parameter space. We also set new bounds on the mixing strength of photons with dark photons (A^{'}) from nonobservation of the decay A^{'}→e^{+}e^{-} of the bremsstrahlung A^{'} with a mass ≲23 MeV.

Vapor Annealing and Colloid Lithography: An Effective Tool To Control Spatial Resolution of Surface Modification.

Colloid lithography represents a simple and efficient method for creation of a large-scale template for subsequent surface patterning, deposition of regular metal nanostructures, or periodical surface structures. However, this method is significantly restricted by its ability to create only a limited number of structures with confined geometry and symmetry features. To overcome this limitation, different techniques, such as plasma treatment or tilting angle metal deposition, have been proposed. In this paper, an alternative method based on the vapor annealing of ordered single polystyrene (PS) microspheres layer, followed by the surface grafting with arenediazonium tosylates is proposed. Application of vapor treatment before surface grafting allows effective control of the area screened by PS microspheres. Pristine and vapor-annealed microsphere arrays on the gold substrate were electrochemically modified using ADTs. Subsequent removal of the PS microsphere mask enabled to prepare well-defined nanostructures with controllable surface features. In particular, prepared periodic arrangements were achieved by the grafting of OFGs to the empty interspaces between nanopore arrays. The process of sample preparation was controlled, and the properties of prepared structures were characterized by various techniques, including atomic force microscopy (AFM), conductive AFM, scanning electron microscopy energy-dispersive X-ray spectrometry, Raman spectroscopy, and voltammetry.

Search for Invisible Decays of Sub-GeV Dark Photons in Missing-Energy Events at the CERN SPS.

We report on a direct search for sub-GeV dark photons (A^{'}), which might be produced in the reaction e^{-}Z→e^{-}ZA^{'} via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The dark photons would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75×10^{9} electrons on target. We set new limits on the γ-A^{'} mixing strength and exclude the invisible A^{'} with a mass ≲100 MeV as an explanation of the muon g_{µ}-2 anomaly.

[INFLAMMATION AND CARDIAC INSUFFICIENCY ASSOCIATED WITH INFECTIOUS ENDOCARDITIS].

The study included 62 patients with uncomplicated primary and secondary infectious endocarditis admitted to S.PBotkin city hospital from 2011 to 2014. The emphasis is laid on diagnostic significance of dynamic measurements of the levels of C-reactive protein, tumour necrosis factor and highly sensitive troponin-1 for the evaluation of activity of the infectious/toxic process, severity of the disease, and detection of complications. The study revealed the relationship of the enhanced level of troponin-1 with changes of inflammation markers, morphofunctional characteristics of myocardium, and circulatory failure. Morphologicl study demonstrated inflammatory and dystrophic changes in myocardium, focal and diffuse cardiofibrosis suggesting development of non-coronarogenic myocardial lesions that play an important role in the progress of cardiac failure associated with infectious endocarditis.

[Clinical and morphological aspects of infectious endocarditis].

Comparative analysis of anamnestic, clinical, laboratory and instrumental data involved 106 patients with infectious endocarditis treated in S.P. Botkin City Clinical Hospital in 2000-2011 and 92 ones admitted in 1985-1977. The results give evidence of ongoing pathomorphosis of infectious endocarditis as is apparent from the growing number of male patients, increased frequency of primary cases and previous invasive or intravascular manipulations, thromboembolic complications including pulmonary thromboembolism, right heart chamber endocarditis. Over half of the patients are socially unadapted C-peptide level is of diagnostic value for the assessment of inflammation activity, precursors of natriuretic peptide can be used to detect preclinical and clinical stages of cardiac failure related to infectious endocarditis. There is correlation between severity of inflammation and myocardial dysfunction. Early surgical intervention in the absence of effect of combined antibacterial therapy improves prognosis. Morphological studies of inflammation-related changes in myocardium, destruction of cardiomyocytes, dystrophic processes, and fibrosis play an important role in the development of cardiac insufficiency and prognosis of infectious endocarditis.

Merging gold plasmonic nanoparticles and L-proline inside a MOF for plasmon-induced visible light chiral organocatalysis at low temperature.

Light-driven asymmetric photocatalysis represents a straightforward approach in modern organic chemistry. In comparison to the homogeneous one, heterogeneous asymmetric photocatalysis has the advantages of easy catalyst separation, recovery, and reuse, thus being cost- and time-effective. Here, we demonstrate how plasmon-active centers (gold nanoparticles - AuNPs) allow visible light triggering of chiral catalyst (proline) in model aldol reaction between acetone and benzaldehyde. The metal-organic framework UiO-66-NH2 was used as an advanced host platform for the loading of proline and AuNPs and their stabilization in spatial proximity. Aldol reactions were carried out at a low temperature (-20 °C) under light illumination which resulted in 91% ee with a closed-to-quantitative yield, 4.5 times higher than that without light (i.e. in the absence of plasmon triggering). A set of control experiments and quantum chemical modeling revealed that the plasmon assistance proceeds through hot electron excitation followed by an interaction with an enamine with the formation of anion radical species. We also demonstrated the high stability of the proposed system in multiple catalytic cycles without leaching metal ions, which makes our approach especially promising for heterogeneous asymmetric photocatalysis.

[Injuries to myocardium in infectious endocarditis].

Clinical and morphological characteristics of myocardium in infectious endocarditis (IE) are described as exemplified by pathological changes in the vascular bed, stroma, and myofibrils. Multiple sclerotic changes in myocardium in the form of "sheath sclerosis" were revealed. It is shown that progress of cardiac insufficiency in IE may be due to specific changes in the heart muscle. The necessity of early diagnostics of myocardial lesions is discussed with reference to revision of antibiotic therapy and modern surgical treatment of lE.

Bioinspired superhydrophobic SERS substrates for machine learning assisted miRNA detection in complex biomatrix below femtomolar limit.

Surface-enhanced Raman spectroscopy (SERS) is an analytical method with high potential in the field of medicine. The design of SERS substrates, based on specific morphology and/or chemical modification, allow the recognition of the presence of specific analytes with precision close to a single-molecule detection limit. However, the SERS analysis of real samples is significantly complicated by the presence of a large number of "minor" molecules that can shield the signal from the target analyte and make it impossible to determine it in practice. In this work, an advanced SERS approach was used for the detection of cancer-related miRNA-21 in blood plasma, used as a molecular model background. The approach was based on the combination of the biomimetic plasmon-active SERS substrate, its tuned surface chemistry and advanced SERS data analysis, making use of artificial machine learning. In the first step, biomimetic SERS substrates were created using a butterfly wing as a starting template. The substrates were covered by thin Au layer and covalently grafted with hydrophobic chemical moieties to introduce superhydrophobic and water-adhesive properties. The self-concentration of the analyte on the substrates was achieved by minimizing the contact area between the analyte drop and the substrate, which is facilitated by surface superhydrophobicity and additionally enhanced by drop evaporation on the flipped over substrate. Due to the presence of cancer miRNA and blood plasma background, the measured SERS spectra represent a complex of interfering peaks. Thus, their interpretation was carried out using a specially trained machine learning model. As a result, reliable and repeatable quantitative detection of miRNAs below the femtomolar level (up to 10-16 M) on the background of human blood plasma becomes possible.

Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel.

We report the results of a search for a new vector boson ( A ' ) decaying into two dark matter particles χ 1 χ 2 of different mass. The heavier χ 2 particle subsequently decays to χ 1 and an off-shell Dark Photon A ' ∗ → e + e - . For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay A ' → χ χ ¯ and axion-like or pseudo-scalar particles a → γ γ . With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for A ' masses from 2 m e up to 390 MeV and mixing parameter ε between 3 × 10 - 5 and 2 × 10 - 2 .

Plasmon-active optical fiber functionalized by metal organic framework for pesticide detection.

Functional plasmonic fiber for detection and on-line monitoring of organophosphorus pesticides in water or model soil samples is described. The appearance of the plasmon absorption band was realized through the deposition of a thin gold layer on the naked core of multimode optical fiber. The metalorganic frameworks (MOF-5) layer was deposited on the gold surface for the introduction of a high affinity towards the target pesticides. The MOF-5 layer affords the extraction of pesticides and their concentration primarily in the "plasmon evanescent wave" space, allowing the detection by the shift of plasmon absorption band. The growth of MOF-5 layer was confirmed using the Raman, XPS and XRD measurements. The entrapping of pesticides was checked using the Raman spectroscopy and ellipsometry, which also indicate the corresponding changes of MOF-5 refractive index. The series of further experiments demonstrate the applicability of proposed fiber sensor for detection of pesticides in soil without the false signals from surrounding media. The main advantages of proposed sensor can be attributed to simplicity, high sensitivity, low cost and the absence of organic solvents for the probe treatment.

Hunting down the X17 boson at the CERN SPS.

Recently, the ATOMKI experiment has reported new evidence for the excess of e + e - events with a mass ∼ 17 MeV in the nuclear transitions of 4 He, that they previously observed in measurements with 8 Be. These observations could be explained by the existence of a new vector X 17 boson. So far, the search for the decay X 17 → e + e - with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X 17 decay with the proposed method. To reach this goal an optimization of the X 17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [1], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.

[Prevention of ventricular fibrillation with the aid of protopine in animal experiments]. / Profilaktika fibrilliatsii zheludochkov serdtsa s pomoshch'iu protopina v eskperimente.

The anti-arrhythmic activity of protopin, quinidine and novocainamide infused intravenously as a preventive and relieving measure was studied in acute experiments on rats with calcium chloride and aconitic arrhythmia. In myocardial fibrillation induced by calcium chloride the contents in the rat heart of adrenalin, noradrenaline, dopa and dopamine were studied by spectrofluorimetry before and after the use of protopin. It was established that in the size of its minimum effective doses which arrest or prevent calcium chloride and aconitic arrhythmias in rats protopin is two to three times more potent than quinidine and novocainamide. The mechanism of the anti-arrhythmic effect of protopin in calcium chloride and aconitic arrhythmias is complex and is due to the suppression of the foci of heterotopic stimulation, decrease in excitability of the myocardial cells and normalization of the catecholamine content in the myocardium.

[Effect of the chemical nature of the carbon source in the medium on the makeup of the biomass]. / Vliianie khimicheskoi prirody istochnika ugleroda v srede na sostav biomassy

The yeast Candida tropicalis, Candida utilis, Trichosporon cutaneum were cultivated on the synthetic medium containing additions of group B vitamins (biotin, thiamin) and glucose, glycerol of lactic acid as the sole source. The protein content, amino acid composition, nucleic acids and complex B vitamins were identified in the resultant biomass. The carbon source in the medium affected these indices. The protein and nucleic acid content also depended on the yeast strain.

[Comparative study of mycoplasmae and stable L-forms of bacteria]. / Sravnitel'noe izuchenie mikoplazm i stabil'nykh L-form bakterii

A comparative study of mycoplasmae and L-form bacteria was carried out. Both of them were well passaged on a special nutrient medium with the addition of thallium acetate, i.e. they were resistant to this factor. But, in difference from the L-form bacteria, mycoplasmae failed to be passaged on the serum-free medium; the cultures of the L-form bacteria were highly resistant to the action of osmotic stabilizers and to the pressure of the nutrient medium of 15 and 30 atm; as to mycoplasmae--they perished at such a high pressure. The majority of mycoplasmae were resistant to the action of osmotic shock, and L-form bacteria lost their viability in distilled water as soon as in 2 hours.

[L-forms of bacteria in the urine of patients with chronic pyelonephritis]. / L-formy bakterii v moche bol'nykh khronicheskim pielonefritom

The authors present the data concerning the study of 200 patients suffering from chronic pyelonephritis; in 28 of these L-forms of bacteria were revealed in the urine. Of 46 L-cultures isolated from these patients 13 reversed into bacterial forms, 8 failed to reverse and were referred to the stable L-forms; the rest 25 L-cultures perished during the 8th--10th passage. This led to a supposition that the relapses and exacerbations of the infectious process in pyelonephritis were associated with the change of the L-forms into bacterial ones, and that the persistence of the L-forms in the kidney tissue promoted the maintenance of the chronic process.