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The identification of the earliest diagnostic markers for infections in newborns remains one of the priorities in neonatology. In our study, we aimed to assess the diagnostic value of presepsin (P-SEP) as a marker for congenital infections in newborn children. The study was prospective in design and took place from January 2020 to February 2021. We enrolled a total of 64 children with a gestational age of 24 to 40 weeks. The study was approved by the Biomedical Research Ethics Committee (Minutes No.12 of 17 November 2016) and the Scientific Council (Minutes No.19 of 29 November 2016) of the V.I. Kulakov NMRC OGP of Ministry of Healthcare of the Russian Federation. Written voluntary consent to the patients’ participation in the study was obtained from their legal representatives. The patients were divided into 2 groups: a group of interest consisting of newborn children with congenital infections (n = 30), and a control group comprising newborns without signs of infection (n = 34). The group of interest included children with congenital pneumonia (n = 25), urinary tract infections (n = 3), and infections specific to the perinatal period, without a focus of infection (n = 2). Gestational age and birth weight were comparable between the groups. No statistically significant differences in CRP levels, neutrophil counts, immature-to-total neutrophil ratios and lactate concentrations on days 1 and 3 of life were found between the two groups. In the group of interest, P-SEP on day 1 of life was significantly higher than in the control group (р = 0.015). Our findings suggested that P-SEP levels ≥ 481 pg/mL could predict a high risk of congenital infections in newborns. The sensitivity and specificity were 91.0% and 60.0% respectively. P-SEP levels determined in capillary blood were similar to those obtained from venous blood samples suggesting that either can be used for P-SEP measurement with equal success. P-SEP levels were shown to decrease by day 3 of life in the children with congenital infections who had been treated with antibiotics.

Synthetic diamond single crystals were grown by the thermal gradient method in a high-pressure apparatus in the presence of solvent catalysts (nickel, iron). Absorption, luminescence, and photoluminescence excitation measurements were performed in order to determine the nature of impurity-defect complexes in both as-grown crystals and crystals treated at high temperature (T≈2000–2200 K) and high pressure (P≈6.0–6.5 GPa). Different luminescence and absorption bands were assigned to impurity centers containing nitrogen and nickel atoms.

The low-temperature photoluminescence (PL) measurements (down to 4.2 K) were employed for the investigations of the defects and impurities in multicrystalline silicon (mc-Si) samples grown by block-casting method. The optical properties of as-grown, irradiated by gamma-rays, heat and hydrogen plasma treated samples were studied. It was found that carbon and oxygen as the residual impurity atoms are responsible for the formation of the zero-phonon PL lines with 0.9355 eV (T line) and 0.9652 eV (I line) after heat treatments at about 350–550°C. The appearance of PL lines with the energies of 0.9697 eV (A line) and 0.7894 eV (C line) after a gamma-rays irradiation can be attributed to the formation of carbon- and oxygen-related centers, respectively. The comparison of the PL properties of the mc-Si samples with the mono-crystalline one is performed. It is shown that the main peculiarities of the low-temperature PL spectra of mc-Si can be explained both by the influence of residual impurities and the residual strains in this material.

Optical properties of structurally perfect CuInSe2 single crystals were studied in the temperature range of 4.2–300 K with the use of photoluminescence, optical absorption, optical reflection, and wavelength-modulated optical reflection (WMOR). The intense lines of free excitons A (∼1.0414 eV) and B (∼1.0449 eV) with a half-width of ∼0.7 meV at 4.2 K are found to be related to two extrema of valence band split by a crystal field. The excitons emission line C (∼1.2779 eV) in WMOR spectra are related to a lower valence band split-off by spin-orbit interaction. Within the context of the quasi-cubic Hopfield model, the parameters of valence band splitting ΔCF=5.2 meV and ΔSO=234.7 meV defined by the crystal and spin-orbit interaction, respectively, are calculated. In the region of the fundamental absorption edge, the lines of bound excitons are found with a half-width ∼0.3 meV that is indicative of a high quality of grown CuInSe2 crystals.

Using low-temperature (4.2–78 K) photoluminescence, we study the processes of defect formation in silicon films on sapphire irradiated with high-energy particles (electrons, γ-quanta of60Co). It is established that carbon atoms, as a residual process impurity, participate in the formation of luminescence centers stable up to annealing temperatures of about 550 K. For carbon-containing centers we reveal a shift in the spectral lines relative to their position in spectra of single-crystal silicon. It is proposed that this spectral shift is associated with the presence of internal stresses of about 5·108 N/m2 in the silicon films.

The free-exciton series with n=1,2 in high perfect CuInSe2 and CuGaSe2 single crystals have been observed in photoluminescence. The exciton binding energy and direct energy gap are estimated as 9.5 meV and 1.7305 eV at 4.2 K for CuGaSe2. New values are determined for the band gap energy Eg=1.0459 eV and for the excitonic binding energy 5.1 meV in CuInSe2 at 4.2 K. The temperature dependence of the n=1 excitonic line between 4.2 and 300 K have been studied.

An investigation is made of the low-temperature (4.2–78 K) photoluminescence of single crystals of cadmium diarsenide grown from the gas phase and by the Bridgman method. Radiation near the fundamental absorption edge is detected, which is attributed to annihilation of free excitons with simultaneous emission of phonons (the lines 1.0029 and 0.9840 eV at 4.2 K). The optical width of the forbidden band is estimated at 4.2 K.

Low-temperature photoluminescence (4.2 and 35 K) has been used to study the defects created by high-energy particle irradiation (gamma rays, electrons, ions) of silicon on sapphire (SOS) films. It was found that the noble gas atoms implanted into silicon layers take an active part in the processes of interaction with radiation damage. Data on the temperature stability of luminescence centres are given. The residual compressive stress in SOS films is estimated using the photoluminescence method.

The luminescence and transmission spectra of single crystals of the semiconductor compounds ZnAs 2 , Zn 3 As 2 , and CdAs 2 in the wide temperature range of 4.2–300 K are studied. A number of previously unknown luminescence (absorption) bands are revealed in the near-infrared region at 1–1.5 μ m. These bands are assumed to be caused by different residual impurity atoms or defects. The energy band structures, radiative recombination mechanisms, the nature of the luminescence centers, and other physical aspects of these materials are discussed. An analysis of studies of the optical properties of ZnAs 2 , Zn 3 As 2 and CdAs 2 single crystals shows that these compounds are promising as materials for cut-off filters and immersion lenses for the infrared region of the spectrum.

Photoluminescence (PL) and optical absorption (OA) measurements have been used to study CuInS2xSe2(1−x) alloy at temperatures down to 4.2 K for x from 0 to 1. Exciton related PL lines were observed for all studied elemental compositions. For x=0 the A and B excitons were resolved in the PL spectra. Dependencies of the optical band gaps of the alloy on the elemental composition were derived from both the PL and OA spectra. The band gap was found to be changing nonlinearly with respect to x. The derived bowing coefficient b=0.13 eV. The possible nature of the observed luminescence centres and radiative recombination mechanisms is discussed.

The formation of radiation damage in silicon crystals after low-temperature (20 to 25 K) electron irradiation or ion implantation is studied by the luminescence method. It is found that the carbon impurity atoms take an active part in the processes of interaction with primary radiation defects at low temperatures. Implantation of carbon ions confirms their participation in the formation processes of the luminescence centers corresponding to the 0.8559 eV electron–vibronic band. The annealing behavior in the temperature range from 20 to 400 K and its comparison with EPR and IR absorption data on radiation damage suggest a correlation of the 0.8559 eV luminescence band with interstitial carbon atoms. [Russian Text Ignored]

Hydrogen- and helium-implanted Czochralski (Cz) silicon was investigated by low-temperature photoluminescence (PL) measurements after post-implantation annealing at 1000°C for 1 h in flowing hydrogen or nitrogen. The PL measurements indicate a rather strong line at about 0.8 eV. The intensity of this line depends on the implantation dose and on the annealing ambient. The observed PL spectra can be attributed to radiative recombination processes at structural defects created during the post-implantation annealing. The applied processes (i.e. H or He implantation, subsequent annealing) can be regarded as a promising method for the development of light emitting Si devices (spectral range of ∼0.8 eV), due to the formation of optically active structural defects.

The compound ZnAs 2 is a II-V semiconductor which crystallizes in a monoclinic structure, with the space group P21/C [1]. The progress which has been achieved in the technology for gas phase synthesis of perfect zinc diarsenide crystals, especially the method of directional melt crystallization, has made it possible to carry out detailed studies of various physical properties of this material [2-8]. The optical properties of zinc diarsenide crystals were studied in [3-8]. The direct nature of the band-gap has been established, the intrinsic absorption edge has been used to determine the gap of ZnAs 2 to be 0.92 eV at 300 K [3, 4]. The cathodoluminescence of ZnAs 2 crystals grown from the gas phase was studied in [5]. At low temperatures a number of luminescence bands have been observed in the optical spectrum, due to exciton-impurity complexes. In the present work we have used a high resolution spectral apparatus [9] to study the low temperature photoluminescence of ZnAs 2 crystals grown by directional crystallization from the melt. The luminescence properties of ZnAs 2 produced in this manner have not been studied previously. ZnAs 2 crystals with carrier densities in the range 1015 to 4.1015 cm -3 at 300 K were grown by the vertical Bridgeman technique. Before the luminescence was measured the samples were mechanically polished and chemically etched in a 2:3:1 mixture of HNO3:HCI:H20 to reduce the surface recombination rate for the nonequilibrium charge carriers. In different cases, the luminescence was observed from the natural crystal facets or from fresh cleavage surfaces. The luminescence spectra were recorded for temperatures from 4.2 to 300 K. The nonequilibrium carriers were excited by light from a high pressure xenon lamp, model DKSSh-1000, through a water filter 10 cm thick and Karl-Zeiss CZC-22 and VG-17 filters or by use of a Karl-Zeiss ILA-120 argon laser, with a cw multiline power of 4 W. The spectra were analyzed using an MDR-23 monochromator with a 600 line/mm diffraction grating, providing a dispersion of 2.6 nm/mm. A copper-compensated germanium photomultiplier cooled with liquid nitrogen was used to detect the luminescence. In Fig. 1 we show survey spectra of the photoluminescence for zinc diarsenide crystals, recorded at the temperatures 300, 78, and 4.2 K with spectral resolutions of 2, 1, and 0.5 meV, respectively. The room temperature luminescence exhibits a band with a maximum at 0.955 eV (Fig. la). The band is clearly asymmetric, with a steeper low-energy wing, and its halfwidth is - 38 meV ( - 1.5 kT at 300 K). If we suppose that this band is due to radiative recombination of nonequilibrium carriers via energy states in the allowed bands, then the band gap of ZnAs 2 at 300 K, determined from the maximum of the emission, would be -0.955 eV, which is significantly larger than the band gap (-0.92 eV) obtained from IR absorption spectra [3, 4]. However, analysis of the temperature dependence of the shape and energy displacement of the 0.955 eV band as the temperature is lowered indicates that it is due to optical transition via the energy states in the gap. The luminescence of samples immersed in liquid nitrogen exhibits a number of bands with maxima at 1.042, 1.033, 1.011, and 0.965 eV, or 1.033, 1.027, and 0.965 eV, depending on the structural perfection of the zinc arsenide crystal. The band at 0.955 eV (Fig. la) shifts by 10 meV as the temperature is lowered from 300 to 78 K, and its shape becomes more symmetric. We note that the shape of the luminescence spectra detected at 78 K apparently is determined by the presence of some local detects in the crystals, and by their relative concentrations. As a rule, the spectra fall in two classes (Fig. lb), observed for different crystals. The energy position of the most intense band and the appearance of the 1.011 eV maximum depend on which luminescence centers have the dominant concentration in the crystal. The contributions of different sorts of defects to the spectral shape detected at 78 K is more readily visible when the spectra are observed at 4.2 K. In Fig. lc we show the luminescence spectrum of a ZnAs 2 crystal immersed in liquid helium. A large number of lines are observed in the

The luminescence and transmission of zinc diarsenide single crystals near the fundamental absorption edge have been investigated in the temperature range 4.2–300 K. Intense luminescence and absorption lines at 1.0384, 1.0488, and 1.0507 eV, referring to the ground state (n=1) and excited states (n=2, n=3) of a free exciton were observed at low temperatures. The free-exciton binding energy was found to be ∼13.9 meV on the basis of the hydrogen-like model and the direct band gap was found to be 1.0523, 1.0459, and 0.9795 eV at 4.2, 78, and 300 K, respectively.

The processes of defect formation in single crystals of gallium arsenide electron-irradiated at cryogenic temperatures (∼20 K) have been investigated by the luminescence method. It is shown that at such temperatures the primary radiation-induced defects, in particular, intrinsic interstitial atoms, can migrate in a crystal and form complexes with their participation.

The systematical low-temperature (4.2 K) photoluminescence (PL) study of the formation kinetics of optically active centers in H and He implanted CZ Si, annealed in the temperature range of 200–1000°C is presented. The samples were implanted with H (energy E =80 keV, dose D =10 15 /10 16 cm −2 ) and He ( E =150 keV, D =5×10 14 cm −2 ) ions. It was found that the annealing of H or He implanted samples leads to the appearance and evolution of a number of zero-phonon lines as well as of broad bands. The origin of the observed lines and bands is discussed. It is assumed that the strong stresses around hydrogen-related structural defects (voids, bubbles) during the annealing at 500–700°C of H implanted Si lead to the formation of a specific optical center M′ (∼1.012 eV PL line).