[Comparative analysis of the intestinal microbiota in patients with exocrine pancreatic insufficiency of various severity].

BACKGROUND: Exocrine pancreatic insufficiency (EPI) is a critical host factor in determining the composition of the gut microbiota. Diseases that cause exocrine insufficiency can affect the gut microbiome, which can potentiate disease progression and complications. To date, the relationship of exocrine insufficiency in various pancreatic (PA) pathologies, in chronic pancreatitis (CP), with dysbiotic changes in the intestinal microbiota (IM) has not been reliably studied. The available data are heterogeneous and contradictory, which determines the need for further research. AIM: To conduct a comparative analysis of the taxonomic composition of the intestinal microbiota in patients with CP of various etiologies, without or with the presence of EPI of varying severity, as well as patients with severe EPI with a history of surgical intervention (SI) on the pancreas. MATERIALS AND METHODS: A total of 85 patients were included in the study. Patients were divided into groups according to the severity of EPI: Group 1 (n=16) - patients with CP without EPI; Group 2 (n=11) - patients with CP and mild EPI; Group 3 (n=17) - patients with severe CP and EPI; Group 4 (n=41) - severe EPI in persons with a history of SI on the pancreas. Verification of CP was carried out according to clinical, anamnestic and instrumental data. The degree of EPI was determined by the level of pancreatic elastase-1 (PE-1) feces. Informed consent for the study was obtained for each patient, an anamnesis was collected, physical and laboratory examinations were performed, and a stool sample was obtained. DNA was extracted from each stool sample, the taxonomic composition of BM was determined by sequencing the bacterial 16S rRNA genes, followed by bioinformatic analysis. RESULTS: We followed the changes in the gut microbiota from a group of patients with CP without EPI to a group with severe EPI, in those who underwent SI. At the level of the phylum, the IM of all groups showed the dominance of Firmicutes, with the lowest representation in the severe EPI group, both with SI and CP, and the growth of the Actinobacteria, Verrucomicrobiota and Fusobacteria types. The differential representation of childbirth varied: in patients with severe EPI and CP, compared with mild, statistically significant genera - Akkermansia, Ruminococcus gauvreauii group and Holdemanella; compared with CP without exocrine insufficiency, Prevotella, Ruminococcus gauvreauii group, Peptostreptococcus and Blautia dominated. The CP group with mild EPI was dominated by the following genera: Lachnospiraceae_ND 2004 group, Faecalitalea, Fusobacterium, Catenibacterium, Roseburia, Atopobium, Cloacibacillus, Clostridium innococum group, Ruminococcus torques group. All groups showed a low diversity of taxa with a predominance of opportunistic flora, including participants in oncogenesis. CONCLUSION: The results of the study show that patients with CP of various etiologies and patients with severe EPI who underwent specific intervention on the pancreas have intestinal microbiota dysbiosis, the severity of which is significantly influenced by the degree of EPI.

Pulse-width-dependent critical power for self-focusing of ultrashort laser pulses in bulk dielectrics.

Microscale filamentation of 0.25 NA-focused, linearly and circularly polarized 1030 nm and 515 nm ultrashort laser pulses of variable pulse widths in fused silica, fluorite, and natural and synthetic diamonds demonstrates the Raman-Kerr effect in the form of critical pulse power magnitudes, proportional to squared wavelength and inversely proportional to laser pulse width of 0.3-10 ps. The first trend represents the common spectral relationship between the quantities, while the second indicates its time-integrated inertial contribution of Raman-active lattice polarization, appearing in transmission spectra via ultrafast optical-phonon Raman scattering. The optical-phonon contribution to the nonlinear polarization could come from laser field-induced spontaneous/stimulated Raman scattering and coherent optical phonons generated by electron-hole plasma with its clamped density in the nonlinear focus. Almost constant product value of the (sub)picosecond laser pulse widths and corresponding critical pulse powers for self-focusing and filamentation in the dielectrics ("critical pulse energy") apparently implies constant magnitude of the nonlinear polarization and other "clamped" filamentation parameters at the given wavelength.

Broadband and fine-structured luminescence in diamond facilitated by femtosecond laser driven electron impact and injection of "vacancy-interstitial" pairs.

Ultrafast heating of photoionized free electrons by high-numerical-aperture (0.25-0.65) focused visible-range ultrashort laser pulses provides their resonant impact trapping into intra-gap electronic states of point defect centers in a natural IaA/B diamond with a high concentration of poorly aggregated nitrogen impurity atoms. This excites fine-structured, broadband (UV-near-infrared) polychromatic luminescence of the centers over the entire bandgap. The observed luminescence spectra revealed substitutional nitrogen interaction with non-equilibrium intrinsic carbon vacancies, produced simultaneously as Frenkel "vacancy-interstitial" pairs during the laser exposure.

IR femtosecond laser micro-filaments in diamond visualized by inter-band UV photoluminescence.

Single microscale filaments were produced in monocrystalline Ia-type diamond by 1030 nm, 300 fs laser pulses tightly focused at NA = 0.3 and different peak powers, visualized by transverse imaging and spectrally characterized by longitudinal micro-spectroscopy, using intrinsic UV A-band photoluminescence (PL) with its peak at about 430 nm. Power-dependent scaling relationships for the local PL yield and diameters of the accompanying luminous micro-channels of recombining electron-hole plasma indicate a transition from three-photon absorption to free-carrier plasma absorption, as the consequent energy deposition mechanisms at increasing peak laser power. Power-dependent elongation of the luminous micro-channels versus peak laser power fitted by a Marburger formula yields, on average a diffraction-based estimate of 0.6 MW critical power for self-focusing within the diamond at the pump laser wavelength of 1030 nm.

[The prevalence of sarcopenia in patients with chronic pancreatitis: a meta-analysis].

AIM: Systematization of data on the prevalence of sarcopenia in patients with chronic pancreatitis (CP). MATERIALS AND METHODS: MEDLINE/PubMed, EMBASE, Cochrane, the Russian Science Citation Index (RSCI) through June 2020 were searched to identify studies evaluating the prevalence of sarcopenia in CP. Additionally, a search for relevant abstracts was carried out in the electronic databases of the conferences of the European Pancreatic Club (EPC), the International Association of Pancreatology (IAP) and the European Congress of Radiology (ECR). For the final analysis, publications were selected that used validated muscle mass assessment tests with detailed descriptive statistics to enable the resulting data to be included in the meta-analysis. RESULTS: The final analysis included 7 studies involving 604 patients with CP. The pooled prevalence of sarcopenia in patients with CP was 42.09% (95% confidence interval CI 27.84557.055). There was significant heterogeneity between the results (p0.0001; I2=90.81%). When studies with a total sample of less than 50 patients were excluded from the meta-analysis, the overall prevalence of sarcopenia in patients with CP was 22.24% (95% CI 15.47529.847). CONCLUSION: The present meta-analysis demonstrated that sarcopenia is a common complication of CP and is observed in about 2 out of 5 patients with this inflammatory disease of the pancreas. Given the high incidence of adverse outcomes associated with sarcopenia, it is necessary to promptly diagnose this pathological condition in patients with CP.

[The effectiveness of pancreatic enzyme replacement therapy using microencapsulated pancreatin preparations in the correction of nutritional status in patients with chronic pancreatitis: a prospective observational study].

AIM: The goal is to evaluate the effectiveness of pancreatic enzyme replacement therapy (PERT) using microencapsulated pancreatin preparations for the correction of nutritional status in patients with chronic pancreatitis (CP) and associated exocrine pancreatic insufficiency (EPI). MATERIALS AND METHODS: The study included 58 patients with CP who were divided into two groups depending on the results of a laboratory assessment of indicators of nutritional status: group I (n=30) consisted of patients with CP and signs of EPI (according to low elastase test values) without deviations in nutritional status; Group II (n=28) consisted of patients with CP with a EPI and an abnormal nutritional status. In both groups, patients during the entire observation period (8-12 months) received PERT using microencapsulated pancreatin preparations at a dose adjusted for the severity of permanent residence permit. Before and after the PERT course, the dynamics of anthropometric [body weight, body mass index (BMI)] and laboratory indicators of nutritional status (total protein, albumin, vitamins D and B12, transferrin, iron and magnesium) were evaluated. RESULTS: After the completion of PERT, a significant tendency towards an increase in BMI in patients was noted in both groups. In group I, this indicator increased from 21.45 [95% confidence interval (CI) 19.80-23.92] kg/m2 to 22.15 (95% CI 20.31-23.86) kg/m2, and in II group - from 19.22 (95% CI 18.33-21.99) kg/m2 to 22.0 (95% CI 19.97-24.08) kg/m2. At the same time, the duration of PERT (months) significantly correlated with the dynamics of the patient's body weight (r=0.4679; 95% CI 0.2384-0.6479, p=0.0002). When assessing laboratory markers of nutritional status after PERT, a general tendency was found to increase the levels of total protein, albumin, vitamin D, magnesium, transferrin, and iron in both groups, however, statistically significant differences in the dynamics were observed mainly in group II patients. So, the level of total protein in group II increased from 69.05 (95% CI 65.6717-70.9000) g/l to 72.8 (95% CI 71.1358-74.9000) g/l, vitamin D - from 10.6 (95% CI 32.8397-38.9603) ng/ml to 17.1 (95% CI 12.0166-23.6232) ng/ml, magnesium - from 0.72 ( 95% CI 0.6892-0.7825) mmol/L to 0.795 (95% CI 0.7692-0.8800) mmol/L, and transferrin from 2.91 (95% CI 2.1800-3.3656 ) g/l to 2.92 (95% CI 2.4000-3.5200) g/l. CONCLUSION: A prospective observational study demonstrated the effectiveness of PERT using microencapsulated pancreatin preparations in the correction of nutritional status in patients with CP.

Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape.

We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064 nm pulsed beams propagate from wider (122 µm) into smaller (37 µm) diameter. In the passive mode, increasing the input beam peak power above 20 kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600 nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length.

The novel technique of microwave heating of infant formulas and human milk with direct temperature monitoring.

We discuss the physical mechanisms of microwave heating of milk and infant formulas, and possible causes of nutrient degradation and scalds of infants reported in a number of papers. We list the advantages of microwave heating, formulate criteria of safe heating, and discuss discrepancies between different papers. A novel technique of microwave heating which prevents scalds and saves nutrients is reported. It features an appropriate and stepless microwave power control with direct temperature monitoring under forced permanent mixing. The discussed heating method does not kill live lactobacilli, has no influence on pathogen growth and does not modify the content of nutrients. We conclude that guidelines, which prohibit milk heating in domestic microwave ovens, are quite correct. Nevertheless, specific techniques of microwave heating can be successfully used due to their usability, fast heating, guaranteed precise target temperature and overall automation.

Nonlinear Generation of Vorticity by Surface Waves.

We demonstrate that waves excited on a fluid surface produce local surface rotation owing to hydrodynamic nonlinearity. We examine theoretically the effect and obtain an explicit formula for the vertical vorticity in terms of the surface elevation. Our theoretical predictions are confirmed by measurements of surface motion in a cell with water where surface waves are excited by vertical and harmonic shaking the cell. The experimental data are in good agreement with the theoretical predictions. We discuss physical consequences of the effect.

Negative Coulomb Drag in Double Bilayer Graphene.

We report on an experimental measurement of Coulomb drag in a double quantum well structure consisting of bilayer-bilayer graphene, separated by few layer hexagonal boron nitride. At low temperatures and intermediate densities, a novel negative drag response with an inverse sign is observed, distinct from the momentum and energy drag mechanisms previously reported in double monolayer graphene. By varying the device aspect ratio, the negative drag component is suppressed and a response consistent with pure momentum drag is recovered. In the momentum drag dominated regime, excellent quantitative agreement with the density and temperature dependence predicted for double bilayer graphene is found.

Fiber-optic magnetic-field imaging.

We demonstrate a scanning fiber-optic probe for magnetic-field imaging where nitrogen-vacancy (NV) centers are coupled to an optical fiber integrated with a two-wire microwave transmission line. The electron spin of NV centers in a diamond microcrystal attached to the tip of the fiber probe is manipulated by a frequency-modulated microwave field and is initialized by laser radiation transmitted through the optical tract of the fiber probe. The two-dimensional profile of the magnetic field is imaged with a high speed and high sensitivity using the photoluminescence spin-readout return from NV centers, captured and delivered by the same optical fiber.

Fiber-optic magnetometry with randomly oriented spins.

We demonstrate fiber-optic magnetometry using a random ensemble of nitrogen-vacancy (NV) centers in nanodiamond coupled to a tapered optical fiber, which provides a waveguide delivery of optical fields for the initialization, polarization, and readout of the electron spin in NV centers.

Hybrid mode-locked erbium-doped all-fiber soliton laser with a distributed polarizer.

A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.

[The up-to-date methods of management of NSAIDs-induced injuries of small intestine].

In the article the incidence, pathogenesis, clinical featuries, diagnostic, prevention and treatment of NSAIDs-induced injuries of small intestine are presented. The different strategies of management of NSAID-induced enteropathy, such as use of PPI, COX-2-inhibitors, prostaglandins, antibiotics and probiotics, new combination of NSAIDs with phosphatidylcholine, NO or H2S, food supplements and other drugs are discussed.

Enhancement of the London penetration depth in pnictides at the onset of spin-density-wave order under superconducting dome.

Recent measurements of the doping dependence of the London penetration depth λ(x) at low T in clean samples of isovalent BaFe2(As(1-x)P(x))2 at T≪T(c) [Hashimoto et al., Science 336, 1554 (2012)] revealed a peak in λ(x) near optimal doping x=0.3. The observation of the peak at T≪T(c), points to the existence of a quantum critical point beneath the superconducting dome. We associate such a quantum critical point with the onset of a spin-density-wave order and show that the renormalization of λ(x) by critical magnetic fluctuations gives rise to the observed feature. We argue that the case of pnictides is conceptually different from a one-component Galilean invariant Fermi liquid, for which correlation effects do not cause the renormalization of the London penetration depth at T=0.

Universal features of counting statistics of thermal and quantum phase slips in nanosize superconducting circuits.

We perform measurements of phase-slip-induced switching current events on different types of superconducting weak links and systematically study statistical properties of the switching current distributions. We employ two types of devices in which a weak link is formed either by a superconducting nanowire or by a graphene flake subject to proximity effect. We demonstrate that independently of the nature of the weak link, higher moments of the distribution take universal values. In particular, the third moment (skewness) of the distribution is close to -1 both in thermal and quantum regimes. The fourth moment (kurtosis) also takes a universal value close to 5. The discovered universality of skewness and kurtosis is confirmed by an analytical model. Our numerical analysis shows that introduction of extraneous noise into the system leads to significant deviations from the universal values. We suggest using the discovered universality of higher moments as a robust tool for checking against undesirable effects on noise in various types of measurements.

Nonlinear conductance of long quantum wires at a conductance plateau transition: where does the voltage drop?

We calculate the linear and nonlinear conductance of spinless fermions in clean, long quantum wires, where short-ranged interactions lead locally to equilibration. Close to the quantum phase transition, where the conductance jumps from zero to one conductance quantum, the conductance obtains a universal form governed by the ratios of temperature, bias voltage, and gate voltage. Asymptotic analytic results are compared to solutions of a Boltzmann equation which includes the effects of three-particle scattering. Surprisingly, we find that for long wires the voltage predominantly drops close to one end of the quantum wire due to a thermoelectric effect.

Quantum-fluctuation effects in the transport properties of ultrathin films of disordered superconductors above the paramagnetic limit.

We study the transport in ultrathin disordered film near the quantum critical point induced by the Zeeman field. We calculate corrections to the normal state conductivity due to quantum pairing fluctuations. The fluctuation-induced transport is mediated by virtual rather than real quasiparticle excitations. We find that at zero temperature, where the corrections come from purely quantum fluctuations, the Aslamazov-Larkin paraconductivity term, the Maki-Thompson interference contribution, and the density of states effects are all of the same order. The total correction leads to the negative magnetoresistance. This result is in qualitative agreement with the recent transport observations in the parallel magnetic field of the homogeneously disordered amorphous films and superconducting two-dimensional electron gas realized at the oxide interfaces.

Distribution of supercurrent switching in graphene under the proximity effect.

We study the stochastic nature of switching current in hysteretic current-voltage characteristics of superconductor-graphene-superconductor junctions. We find that the dispersion of the switching current distribution scales with temperature as σ(I) proportional to T(α(G)) with α(G) as low as 1/3. This observation is in sharp contrast to the known Josephson junction behavior where σ(I) proportional to T(α(J)) with α(J)=2/3. We propose an explanation using a generalized version of Kurkijärvi's theory for the flux stability in rf-SQUID and attribute this anomalous effect to the temperature dependence of the critical current which persists down to low temperatures.

Absorption spectra of e-beam-excited Ne, Ar, and Kr, pure and in binary mixtures.

A technique using the broadband emission of a laser plume as probe radiation is applied to record UV-visible (190-510 nm) absorption spectra of Ne, Ar, and Kr, pure and in binary mixtures under moderate e-beam excitation up to 1 MW/cm(3). In all the rare gases and mixtures, the absorption spectra show continuum related to Rg(2) (+) homonuclear ions [peaking at λ∼285, 295, and 320 nm in Ne, Ar, and Kr(Ar/Kr), respectively] and a number of atomic lines related mainly to Rg(∗)(ms) levels, where m is the lowest principal quantum number of the valence electron. In argon, a continuum related to Ar(2) (∗) (λ∼325 nm) is also recorded. There are also trains of narrow bands corresponding to Rg(2) (∗)(npπ (3)Π(g))←Rg(2) (∗)(msσ (3)Σ(u) (+)) transitions. All the spectral features mentioned above were reported in literature but have never been observed simultaneously. Although charge transfer to a homonuclear ion of the heavier additive is commonly believed to dominate in binary rare-gas mixtures, it is found in this study that in Ne/Kr mixture, the charge is finally transferred from the buffer gas Ne(2) (+) ion not to Kr(2) (+) but to heteronuclear NeKr(+) ion.