Band Intensity Research Articles

Using salted egg white in steamed bread: Impact on functional and structural characteristics

Steamed bread has long been an important part of Chinese cuisine. This study investigated the effects of salted egg white (SEW) (5, 10, 15, and 20% w/w) on the quality of steamed breads. Findings revealed that SEW notably enhanced the bread's volume and texture, with a 20% inclusion significantly boosting water retention and rheological properties, albeit reducing bread's lightness. In addition, the H-bond absorption band intensity in the Fourier transform infrared spectroscopy (FTIR) analysis showed increased peak intensities with higher SEW levels, indicative of protein structure alterations. X-ray diffraction confirmed the presence of an amylose–lipid complex. Scanning electron microscope (SEM) and Confocal laser scanning microscope (CLSM) imaging depicted a smooth, consistent protein network with SEW addition. Consumer sensory evaluation responded favourably to the SEW15 steamed bread, suggesting its potential for food industry application. Overall, the study considers SEW an effective ingredient for improving steamed bread quality.

Enhanced UVB 311 emission in Sb2O3–SiO2 glasses doped with Gd2O3 and tailored Pb3O4 content for potential phototherapy

This study investigates the enhancement of the sharp 311 nm UVB emission from Gd3+ ions in antimony silicate glass system doped with a fixed concentration of Gd2O3 (1.0 mol%) and varying amounts of red lead (40–10 mol%). The emission spectra revealed an intense sharp UVB band at 311 nm, originating from the 6P7/2 → 8S7/2 transition of gadolinium ions upon excitation at 273 nm. Interestingly, the intensity of this band nearly doubles as the Pb3O4 content decreases from 40 to 10 mol%. Such improvement was attributed to the decomposition of Pb3O4 into various phases that include α-PbO2, β-PbO2 polymorphs, and PbO. Out of these decomposition products, PbO acted as modifiers, reduced phonon losses and consequently enhanced the emission intensity. The decrease in Pb3O4 content is also hypothesized to promote de-clustering of Gd3+ ions within the glass matrix. This de-clustering reduced cross-relaxation losses, further contributed to the observed emission enhancement. In summary, this study demonstrated a successful strategy for boosting the UVB emission from Gd3+ ions in antimony silicate glasses by manipulating the content of Pb3O4.

MODIFICATION OF PINDIGA BENTONITE CLAY WITH DIDODECYLDIMETHYLAMMONIUM BROMIDES SURFACTANT FOR FOUNDRY USE

Bentonite clay from Pindiga, Gombe State, Nigeria, was surface modified with didodecyldimethylammonium bromides (DDAB) by the Base Exchange (cation exchange capacity) method for its possible use in foundries. The surfaces of the unmodified and modified Pindiga bentonite clay were characterised by means of spectroscopic, diffraction, and scanning methods (X-Ray fluorescence spectrometry (XRF)Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM).XRF showed that unmodified sample was rich of montmorillonite (MMt) with ca +2 as exchangeable cation, FTIR analysis revealed that unmodified water absorption causes stretching and bending vibrations for hydroxyl groups, with the most intense bands in the low-frequency region, while DDAB organo-bentonites showed slight changes in wave bands, with a strong methyl band and a weak methyl band indicative of long-chain linear aliphatic structure. The basal spacing of the unmodified bentonite sample was 1.52 nm, and after modification with DDAB, it improved to 2.1 nm as determined from the X-ray diffraction (XRD) analysis. Results of the SEM images revealed rougher surfaces with uniformly dispersed small particles of grain-like structures characteristic of the unmodified, while theorgano-modified bentoniterevealed clusters of different sizes and shapes, larger Fe 3+ ions replacing smaller Al 3+ ions at octahedral sites, discontinuous layers enveloping large grains, polygonal growth foams with octahedral and tetrahedral shapes, mixed layers of calcium bentonite, and particle sizes less than 200nm. The study concluded that modified bentonite with didodecyldimethylammonium bromides gives good microstructure, increases rigidity, and improve thermal stability, to the organoclays. Therefore, it is recommended that DDAB bentonite be used as binder for foundries.

Raman spectroscopy‐based molecularly imprinted polymer sensor for sensitive detection of lysophosphatidic acid in serum

AbstractLysophosphatidic acid (LPA) has significant potential as a biomarker for diagnosis of ovarian cancer in female patients because it is present throughout all phases of the illness. Regrettably, there is not a clinically useful test for this biomarker yet. In this work, an ultra‐detection of LPA molecule by Raman spectroscopy‐based molecularly imprinted polymer (MIP) in serum samples is reported. β‐CD was synthesized to facilitate the collection of Raman spectroscopy and combined with MIP to denote it as β‐CD‐MIP for the adsorption of LPA with high sensitivity and selectivity. Linear regression model in serum samples shows peaks at 1100 and 1116 cm−1, respectively. A satisfactory linear fit was seen with LPA concentration log I = 3.7 log C + 1255.74 and with spiked serum log I = 4.6 log C + 327.22, respectively. The literature survey suggests the threshold LPA level in healthy person is 1.50 μM/L whereas the LPA level rises in patients with benign ovarian cancer tumor as 7.90 μM/L. This LPA level rises to 16.99 μM/L in ovarian cancer patients. On the basis of the band intensity, the limit of detection of the β‐CD‐MIP sensor for LPA was recorded as 0.003 μM/L. The binding constant of β‐CD‐MIP for LPA in serum was 0.031–0.003 μM/L, respectively. β‐CD‐MIP gel was optimized, characterized, and successfully applied on spiked serum samples. The findings of this research show that this substrate has a lot of potential for ultradetection of trace amounts of LPA molecule from the serum samples. The MIP sensor is robust, recyclable, efficient, and selective.

Changes in characteristics of spermatogonial stem cells in response to heat stress in stallions

Spermatogonial stem cells (SSCs) are essential for the maintenance of male fertility and survival of species. Environmental conditions, notably heat stress, have been identified as important causes of male infertility and have a negative impact on SSCs. Animals with cryptorchid testes (CT) are optimal models for the study of long-term heat stress-related changes in germ cells. The effect of heat stress on germ cells differs depending on the spermatogenesis stage. Thus, verifying whether the specific phase of spermatogenesis is dependent or independent of heat stress in stallions is important. We evaluated the heat stress-related response of SSCs by comparing the relative abundance of mRNA transcripts and expression patterns of the undifferentiated embryonic cell transcription factor 1 (UTF-1) and deleted in azoospermia-like (DAZL) in the seminiferous tubules of CT and normal testes (NT) of stallions using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, and western blotting. We also analyzed the relative abundance of mRNA of different proliferative markers, including minichromosome maintenance 2 (MCM2), marker of proliferation Ki-67 (MKI-67), and proliferating cell nuclear antigen (PCNA). Testicular tissues from four Thoroughbred unilateral cryptorchid postpubertal stallions were used in this study during the breeding season. The relative abundance of the mRNA transcripts of UTF-1 and MCM2 was significantly upregulated in the CT group than that of those in the NT group. In contrast, the relative abundance of the mRNA transcripts of DAZL was significantly downregulated in the CT group than that of those in the NT group. Western blot quantification showed that the relative intensity of UTF-1 protein bands was significantly higher, while that of DAZL protein bands was significantly lower in the CT group than in the NT group. Immunofluorescence studies showed that the number of germ cells immunostained with UTF-1 was significantly higher while immunostained with DAZL was significantly lower in the CT group than that in the NT group. The higher expression level of UTF-1 in the CT group shows that undifferentiated SSCs are not affected by long-term exposure to heat stress. These results also indicate that germ cells after differentiation phase are directly affected by heat-stress conditions, such as cryptorchidism, in stallions.

Observation of exceptionally strong near-bottom flows over the Atlantis II Seamounts in the northwest Atlantic

Knowledge of near-bottom ocean current velocities and especially their extreme values is necessary to understand geomorphology of the seafloor and composition of benthic biological communities and quantify mechanical energy dissipation by bottom drag. Direct measurements of near-bottom currents in deep ocean remain scarce because of logistical challenges. Here, we report the results of flow velocity and pressure fluctuation measurements at three sites with depths of 2573–4443 m in the area where the Gulf Stream interacts with the New England Seamounts. Repeated episodes of unexpectedly strong near-bottom currents were observed, with the current speed at 4443 m of more than 0.40 m/s. At 2573 m, current speeds exceeded 0.20 m/s approximately 5% of the time throughout the entire eight-week measurement period. The maximum flow speeds of over 1.10 m/s recorded at this site significantly surpass the fastest previously reported directly measured current speeds at comparable or larger depths. A strong correlation is found between the noise intensity in the infrasonic band and the measured current speed. The noise intensity and the characteristic frequency increase with the increasing current speed. Machine-learning tools are employed to infer current speeds from flow-noise measurements at the site not equipped with a current meter.

Associations of accelerometer-estimated free-living daily activity impact intensities with 10-year probability of osteoporotic fractures in adults

PurposeAccelerometers are used to objectively measure physical activity; however, the relationship between accelerometer-based activity parameters and bone health is not well understood. This study examines the association between accelerometer-estimated daily activity impact intensities and future risk estimates of major osteoporotic fractures in a large population-based cohort. MethodsParticipants were 3165 adults 46 years of age from the Northern Finland Birth Cohort 1966 who agreed to wear a hip-worn accelerometer during all waking hours for 14 consecutive days. Raw accelerometer data were converted to resultant acceleration. Impact magnitude peaks were extracted and divided into 32 intensity bands, and the osteogenic index (OI) was calculated to assess the osteogenic effectiveness of various activities. Additionally, the impact peaks were categorized into three separate impact intensity categories (low, medium, and high). The 10-year probabilities of hip and all major osteoporotic fractures were estimated with FRAX-tool using clinical and questionnaire data in combination with body mass index collected at the age of 46 years. The associations of daily activity impact intensities with 10-year fracture probabilities were examined using three statistical approaches: multiple linear regression, partial correlation, and partial least squares (PLS) regression. ResultsOn average, participants’ various levels of impact were 8331 (SD = 3478) low; 2032 (1248) medium; and 1295 (1468) high impacts per day. All three statistical approaches found a significant positive association between the daily number of low-intensity impacts and 10-year probability of hip and all major osteoporotic fractures. In contrast, increased number of moderate to very high daily activity impacts was associated with a lower probability of future osteoporotic fractures. A higher OI was also associated with a lower probability of future major osteoporotic fractures. ConclusionLow-intensity impacts might not be sufficient for reducing fracture risk in middle-aged adults, while high-intensity impacts could be beneficial for preventing major osteoporotic fractures.

Yb3+ concentration influence on NIR and upconversion emission and temperature sensing properties of Er3+/Yb3+ co-doped Ta2O5 particles

We synthesized Er3+ and Yb3+ co-doped tantalum oxide (Ta2O5) spherical sub-micrometric particles by a facile method involving formation of tantalum glycolates after pouring in acetone. Then, we investigated how the annealing temperature and Yb3+ concentration (0–30 mol %) affect their structural and luminescence properties. Particle sizes ranged from 146 to 258 nm for the samples annealed at 800 °C. XRD analysis revealed the orthorhombic L-Ta2O5 crystalline structure. The different symmetry sites that the rare earth ions can occupy within the Ta2O5 structure led to intense and broad emission bands centered around 1530 nm. Up-conversion measurements and the calculated number of photons for intense green and red emissions obtained with 980 and 1550 nm excitations helped us to elucidate the mechanisms involved at both excitation wavelengths. We investigated how the 0.5 mol % Er3+/1.5 mol % Yb3+ co-doped Ta2O5 sample performs as a primary thermometer by using the Boltzmann distribution law to predict the absolute temperature from the ratio between the Er3+ 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions. We obtained a maximum relative thermal sensitivity of 0.97 ± 0.04 % K−1 and a minimum δT of 2.41 K. The calculated repeatability was above 95%. These results show that promising nanothermometer based on Ta2O5 with controlled size and morphology can be designed.

Simple and sensitive galactose monitoring based on capillary SERS sensor.

Galactosemia, a severe genetic metabolic disorder, results from the absence of galactose-degrading enzymes, leading to harmful galactose accumulation. In this study, we introduce a novel capillary-based surface-enhanced Raman spectroscopy (SERS) sensor for convenient and sensitive galactose detection. The developed sensor enhances SERS signals by introducing gold nanoparticles (Au NPs) onto the surface of silver nanoshells (Ag NSs) within a capillary, creating Ag NSs with Au NPs as satellites. Utilizing 4-mercaptophenylboronic acid (4-MPBA) as a Raman reporter molecule, the detection method relies on the conversion of 4-MPBA to 4-mercaptophenol (4-MPhOH) driven by hydrogen peroxide (H2O2) generated during galactose oxidation by galactose oxidase (GOx). A new SERS signal was observed, which was generated by H2O2 produced when galactose and GOx reacted. Our strategy yielded a quantitative change in the SERS signal, specifically in the band intensity ratio of 998 to 1076 cm-1 (I998/I1076) as the galactose concentration increased. Our capillary-based SERS biosensor provides a promising platform for early galactosemia diagnosis.

The pH effects on thermal amyloid fibrillation kinetics of hen egg‐white lysozyme using new normalization factor for Raman spectroscopy

The <i>p</i>H effects on thermal amyloid fibrillation kinetics of hen egg‐white lysozyme using new normalization factor for Raman spectroscopy

The interactions of pectin with TiO2 nanoparticles measured by FT-IR are confirmed in a model of the gastrointestinal tract

The presence of nanoparticle fractions (<100 nm, NPs) in the food additive TiO2 (E171) rises concerns about its potential harmful impact on human health. The knowledge about the interaction of TiO2 NPs with food components is limited to proteins or polyphenols. The present paper is the first to report on interactions between TiO2 NPs and high molecular pectins that form gels in boluses and are remain nearly intact during digestion until they reach the colon. Direct interactions were studied using Fourier Transform Infrared Spectroscopy while indirect ones were monitored by measuring the “absorption” of TiO2 using a 0.2 microfiltration membrane, during in vitro digestion in a model of the gastro-intestinal tract. The FT-IR spectra registered for pectin-TiO2 NPs solutions confirmed changes in band intensities at 1020, 1100, 1610, and 1740 cm−1, suggesting interactions taking place mainly via the COO– groups. Furthermore, the I(1020)/I(1100) ratio was decreased (C-O stretching vibrations), suggesting partial blocking of the skeletal vibrations caused by interactions between pectin and TiO2. The modelled in vitro digestions confirmed that the “availability” of Ti was reduced when TiO2 NPs were combined with pectin, as compared to TiO2 NPs “digested” alone.

Effects of Eleutherine bulbosa extract on the myofibrillar protein oxidation and moisture migration of yak meat under oxidation stress

The influence of Eleutherine bulbosa (EB) extract at various levels (1, 4, 7, 10 or 13 g/kg) on the myofibrillar protein oxidation and moisture migration of yak meat in Fenton oxidation system was investigated. The results showed that inclusion of EB extract in yak meat efficiently inhibited carbonyl formation triggered by hydroxyl radicals. Supplementation of EB extract at 1–10 g/kg manifested more contents of the active sulfhydryl, ε-NH2 groups and α-helix structure, and higher solubility of myofibrillar proteins (MPs), but alleviated the turbidity of MPs. However, adding high level of EB extract (13 g/kg) induced the loss of free amine and α-helix content and resulted in more aggregation of MPs. The SDS-PAGE demonstrated that adding 1–7 g/kg EB extract had an obvious protective effect for myosin heavy chain and actin, whereas 10 or 13 g/kg EB extract led to weakened intensities of protein bands. DSC and LF-NMR analysis revealed that 7 g/kg EB extract had appreciable effects on thermal stabilities of MPs, and improved the hydration of yak meat induced by oxidation, while 13 g/kg EB extract accelerated MP structure destabilization and lowered water retention. Our results suggested that incorporation of low levels of EB extract (1–7 g/kg) effectively retarded the oxidative damage to MPs and EB extract could be a promising natural antioxidant in meat processing.

Heat Treatment and Homogenization Influence the Gastric Digestion of Bovine Milk Protein in Growing Pigs as an Adult Human Model

BackgroundBovine milk processing influences the structure of the curd formed during gastric digestion, which may alter gastric protein hydrolysis and impact amino acid (AA) release into the small intestine. ObjectivesThis study aimed to determine the influence of heat treatment and homogenization on the gastric protein digestion and AA emptying of bovine milk. MethodsNine-wk-old pigs (n = 144) consumed either raw, pasteurized nonhomogenized (PNH), pasteurized homogenized (PH), or ultra-high-temperature homogenized (UHT) bovine milk for 10 d. On day 11, fasted pigs received the milk treatment (500 mL) before gastric contents were collected at 0, 20, 60, 120, 180, and 300 min postprandially. The apparent degree of gastric protein hydrolysis (based on the release of free amino groups), apparent gastric disappearance of individual proteins [based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel band intensity], and the gastric emptying of digested protein and AA were determined. ResultsDuring the first 60 min, the rate of apparent gastric protein hydrolysis was fastest in pigs fed UHT milk (0.29%/min compared with on average 0.07%/min in pigs fed raw, PNH, and PH milk). Differences in the apparent degree of gastric protein hydrolysis and emptying were reflected in the rate of digested protein entering the small intestine. The AA gastric emptying half-time was generally shorter in pigs fed PH and UHT milk than in pigs fed raw and PNH milk. For example, the gastric release of total essential AA was >2-fold faster (P < 0.01) in pigs fed PH or UHT milk than that in pigs fed raw or PNH milk (i.e., homogenized compared with nonhomogenized milk). ConclusionsHeat treatment and homogenization increased the apparent gastric degree of protein hydrolysis and the release of digested protein into the small intestine. However, the rate of AA entering the small intestine was mainly increased by homogenization.

Microwave-assisted and methanol/acetic acid-free method for rapid staining of proteins in SDS-PAGE gels

We describe a microwave-assisted, methanol and acetic acid-free, inexpensive method for rapid staining of SDS-PAGE proteins. Only citric acid, benzoic acid, and Coomassie brilliant blue G-250 (CBG) were used. Microwave irradiation reduced the detection duration, and proteins in a clear background were visualized within 30 min of destaining, after 2 min of fixing and 12 min of staining. By using this protocol, comparable band intensities were obtained to the conventional methanol/acetic acid method.

Using Biotinylated Iron-Responsive Element to Analyze the Activity of Iron Regulatory Proteins.

Iron regulatory proteins (IRP1 and IRP2) are the master regulators of mammalian iron homeostasis. They bind to the iron-responsive elements (IREs) of the transcripts of iron-related genes to regulate their expression, thereby maintaining cellular iron availability. The primary method to measure the IRE-binding activity of IRPs is the electrophoresis mobility shift assay (EMSA). This method is particularly useful for evaluating IRP1 activity, since IRP1 is a bifunctional enzyme and its protein levels remain similar during conversion between the IRE-binding protein and cytosolic aconitase forms. Here, we exploited a method of using a biotinylated-IRE probe to separate IRE-binding IRPs followed by immunoblotting to analyze the IRE-binding activity. This method allows for the successful measurement of IRP activity in cultured cells and mouse tissues under various iron conditions. By separating IRE-binding IRPs from the rest of the lysates, this method increases the specificity of IRP antibodies and verifies whether a band represents an IRP, thereby revealing some previously unrecognized information about IRPs. With this method, we showed that the S711-phosphorylated IRP1 was found only in the IRE-binding form in PMA-treated Hep3B cells. Second, we found a truncated IRE-binding IRP2 isoform that is generated by proteolytic cleavage on sites in the 73aa insert region of the IRP2 protein. Third, we found that higher levels of SDS, compared to 1-2% SDS in regular loading buffer, could dramatically increase the band intensity of IRPs in immunoblots, especially in HL-60 cells. Fourth, we found that the addition of SDS or LDS to cell lysates activated protein degradation at 37 °C or room temperature, especially in HL-60 cell lysates. As this method is more practical, sensitive, and cost-effective, we believe that its application will enhance future research on iron regulation and metabolism.

EFFECT OF DIFFERENT LEVELS OF SALT AND DROUGHT STRESSES ON GENE EXPRESSION OF TWO TOLERANCE-DIFFERENT TOMATO CULTIVARS IN VITRO

A lab experiment was conducted at the Plant Tissue Culture Lab / College of Agricultural Engineering Sciences / University of Baghdad. This experiment was aimed to investigate gene expression index in tomato (Solanum lycopersicum L.) after preparation of salt and simulated drought stresses. Two tomato cultivars were selected which claimed to exhibit different levels of tolerance toward abiotic stresses designated as salt-tolerant Yassamine (Y) and salt-sensitive GS12 (G) to assess the test. Seven day-old seedlings from both cultivars were grown in MS media supplemented with four concentrations of NaCl at 0, 50, 100 and 150 mM and four concentrations of PEG at 0, 10, 20, and 30% for 48 hours. The results were showed that Y cultivar exhibited more proline secretion and chlorophyll content when compared with G. In addition, Y cultivar showed less ion leakage and less affected by elevated abiotic stresses in term of seedling weight variation when compared to G counterparts. The SDS-PAGE gel analysis showed that Y cultivar showed more band intensity when compared with G suggested more corresponding gene expression of tolerant protein against abiotic stresses.

Boosting the UV photo-detecting properties of V2O5 thin films by doping In3+ doping

In recent years, optoelectronic technology has demanded the development of efficient photodetectors by layered semiconductor materials at affordable prices. Herein, we put the efforts to generate V2O5 thin films on the surface of glass slides with diverse insertion of In content (0, 1, 2, 3, 4, and 5 wt%) via cost effective nebulizer spray pyrolysis technique and examined their application in U.V. photosensing. Standard characterization techniques are used for these films to identify the cause of In dopant on its morphological, structural, and opto-electrical properties. X-ray diffraction (XRD) plots confirm the development of single-phase orthorhombic structure grown along [010] direction, without the appearance of foreign phases. Further, the dopant ingredient (In) hikes the crystallinity and crystallite sizes (36–51 nm) up to a certain threshold level (2 wt%) and decreases it for further growing In doping. The Field emission scanning electron microscope (FESEM) images display homogeneous nanorods morphology formation at all doping levels. Doping improved its photon absorption in the U.V. region, and the bandgap obtained from the absorbance spectra tuned to a lower value of 1.98 eV up to 2 wt%. All the created thin films emit intense emission bands at 475 nm and 640 nm. Characterization involving I-V measurements under 365 nm illumination at 5 V bias exhibiting commendable performance in terms of photodetector metrics (Responsivity (R) = 7.96 × 10−1 AW−1, Detectivity (D*)=3.63 × 1011 Jones and External quantum efficiency (EQE) = 186 %) for 2 % In doped V2O5. The same sample exhibits a fast-rising /falling time up to 0.6s /0.7 s, respectively. Our results may widen the field of applications in high-performance U.V. photodetector.

Effect of annealing temperature on the properties and the chromium oxidation state of ZnAl1.94Cr0.06O4 nanoparticles prepared by coprecipitation method

Nanostructured materials doped with Cr+3 have potential applications. However, it has been reported that heat treatment can modify the oxidation state of Cr+3, resulting in the formation of toxic Cr+6 in host matrices such as TiO2, Al2O3, SiO2, ZrO2, and Fe(OH)3. The possibility of this occurrence in nanostructured ZnAl2O4:Cr+3 has not been previously considered. In this study, we report the effect of annealing temperatures within the range of 600–1300 °C on the structure, morphology, optical properties, and, more specifically, the chromium oxidation state of ZnAl1.94Cr0.06O4 nanoparticles obtained through the coprecipitation method. The obtention of single-phase systems with a crystal size ranging from 5.25 nm to 142.75 nm was determined by X-ray diffraction and Rietveld refinement. At 800 °C, a more significant oxidation of Cr+3 was observed, evident in the increased absorption intensity of UV–vis bands associated with Cr+6 and a reduction in magnetic susceptibility at ambient temperature. At 1200 °C, a complete reduction of Cr+6 occurred, leading to the appearance of bands related to Cr+3 in the UV–vis absorption spectra and increased magnetic susceptibility; the results were confirmed by X-ray photoelectron spectroscopy. The outcomes of this study offer new insights into the thermal stability of chromium in ZnAl2O4 nanoparticles.

Methyl- versus ethyl-directed formation of square-planar Cobalt(II) and octahedral Cobalt(III) chelates of the in situ generated Schiff bases

Two mononuclear complexes [Co(LI)2] (1) and [Co(LII)3] (2) (HLI = N-cyclohexyl-3-methoxysalicylideneimine, HLII = N-cyclohexyl-3-ethoxysalicylideneimine) are reported. Although both compounds were obtained using the same synthetic procedure, 1 contains Co(II), while 2 is a Co(III) complex. The crystal structure of 1 was found to be the same as reported recently in the literature, while the crystal structure of 2 was established herein for the first time. The ligands in 1 are trans-1,5-N,O-coordinated, yielding a square planar CoN2O2 coordination core, while complex 2 adopts a meridinal isomeric form with both Δ and Λ configurations (Δ-mer-2 and Λ-mer-2). Optical properties of 1 and 2 were studied by the means of UV–vis spectroscopy in CH2Cl2 and MeOH. Both compounds absorb, mainly, in the UV region due to intraligand transitions and a ligand-to-metal charge transfer. The absorption spectra of both complexes also revealed two low intense bands at about 550 and 650 nm, which were attributed to d–d transitions. Molecular docking was applied to probe 1, Δ-mer-2 and Λ-mer-2 toward a series of the SARS-CoV-2 proteins. Both 1 and 2 are active against all the applied proteins; however, 1 is significantly more efficient with the docking scores being either comparable to or even higher of those of the initial ligands. The best binding affinity for 1 was established for PLpro, Mpro and Nsp3_range 207–379-MES. For both isomers of 2, the best binding scores were revealed with Nsp16_GTA site, PLpro, and Nsp3_range 207–379-MES (for Δ-mer-2) and Nsp16_SAM site (for Λ-mer-2). Ligand efficiency scores for the initial ligands as well as complexes 1 and 2 inside the binding sites of the applied proteins were also calculated. Of all complexes, the ligand efficiency scores for complexes of 1 with PLpro and Mpro are within the recommended ranges for a Hit, and the obtained ligand efficiency scores for complexes PLpro–1 and Mpro–1 are superior to those for the initial ligands.

Thulium-doped titanate-germanate glasses for infrared photonics

In this paper, we performed a comparative spectroscopic analysis of Tm3+-doped glasses based on GeO2-BaO-Ga2O3 (GBG) and TiO2-GeO2-BaO-Ga2O3 (TGBG) to achieve broadband luminescence at 1.8 μm. Glasses were prepared at different doping concentrations (0.05 mol% and 1mol%) in order to investigate the effect of Tm3+ ions as well as host composition (GeO2:TiO2 molar ratios) on near-IR luminescence properties. We report on the hypersensitivity of the transition 3H6 → 3F4 of Tm3+ in a series of titanate-germanate glasses, which was shifted to longer wavelengths with increasing TiO2 concentration. The relative intensity of the main near-IR emission band corresponding to the 3F4 → 3H6 (1.8 μm) transition of Tm3+ was 4.8-fold enhanced for glass with molar ratio GeO2:TiO2 = 1:5 compared to GBG glass system. We observed the luminescence quenching phenomena for samples containing more than 0.5 mol% of Tm3+ ions. The calculated spectroscopic parameters, such as measured luminescence lifetime (τm) and the quantum efficiency (η), were discussed and compared to the different laser glasses. Importantly, luminescence decay curves have been examined using the Inokuti-Hirayama model. Additionally, the correlation between optical properties and local structure in glasses was well evidenced by Raman spectroscopy. The proposed strategy, in combination with various chemical composition of glass host activated by various Tm2O3 concentration, might be beneficial for modern near-infrared photonics.