Proteomics analysis identifies the ribosome associated coiled-coil domain-containing protein-124 as a novel interaction partner of nucleophosmin-1.

BACKGROUND INFORMATION: Coiled-coil domain-containing protein-124 (Ccdc124) is a conserved eukaryotic ribosome-associated RNA-binding protein which is involved in resuming ribosome activity after stress-related translational shutdown. Ccdc124 protein is also detected at cellular localizations devoid of ribosomes, such as the centrosome, or the cytokinetic midbody, but its translation-independent cellular function is currently unknown. RESULTS: By using an unbiased LC-MS/MS-based proteomics approach in human embryonic kidney (HEK293) cells, we identified novel Ccdc124 partners and mapped the cellular organization of interacting proteins, a subset of which are known to be involved in nucleoli biogenesis and function. We then identified a novel interaction between the cancer-associated multifunctional nucleolar marker nucleophosmin (Npm1) and Ccdc124, and we characterized this interaction both in HEK293 (human embryonic kidney) and U2OS (osteosarcoma) cells. As expected, in both types of cells, Npm1 and Ccdc124 proteins colocalized within the nucleolus when assayed by immunocytochemical methods, or by monitoring the localization of green fluorescent protein-tagged Ccdc124. CONCLUSIONS: The nucleolar localization of Ccdc124 was impaired when Npm1 translocates from the nucleolus to the nucleoplasm in response to treatment with the DNA-intercalator and Topo2 inhibitor chemotherapeutic drug doxorubicin. Npm1 is critically involved in maintaining genomic stability by mediating various DNA-repair pathways, and over-expression of Npm1 or specific NPM1 mutations have been previously associated with proliferative diseases, such as acute myelogenous leukemia, anaplastic large-cell lymphoma, and solid cancers originating from different tissues. SIGNIFICANCE: Identification of Ccdc124 as a novel interaction partner of Nmp1 within the frame of molecular mechanisms involving nucleolar stress-sensing and DNA-damage response is expected to provide novel insights into the biology of cancers associated with aberrations in NPM1.

Chromatin modifiers and recombination factors promote a telomere fold-back structure, that is lost during replicative senescence.

Telomeres have the ability to adopt a lariat conformation and hence, engage in long and short distance intra-chromosome interactions. Budding yeast telomeres were proposed to fold back into subtelomeric regions, but a robust assay to quantitatively characterize this structure has been lacking. Therefore, it is not well understood how the interactions between telomeres and non-telomeric regions are established and regulated. We employ a telomere chromosome conformation capture (Telo-3C) approach to directly analyze telomere folding and its maintenance in S. cerevisiae. We identify the histone modifiers Sir2, Sin3 and Set2 as critical regulators for telomere folding, which suggests that a distinct telomeric chromatin environment is a major requirement for the folding of yeast telomeres. We demonstrate that telomeres are not folded when cells enter replicative senescence, which occurs independently of short telomere length. Indeed, Sir2, Sin3 and Set2 protein levels are decreased during senescence and their absence may thereby prevent telomere folding. Additionally, we show that the homologous recombination machinery, including the Rad51 and Rad52 proteins, as well as the checkpoint component Rad53 are essential for establishing the telomere fold-back structure. This study outlines a method to interrogate telomere-subtelomere interactions at a single unmodified yeast telomere. Using this method, we provide insights into how the spatial arrangement of the chromosome end structure is established and demonstrate that telomere folding is compromised throughout replicative senescence.

Dimerization underlies the aggregation propensity of intrinsically disordered coiled-coil domain-containing 124.

Coiled-coil domain-containing 124 (CCDC124) is a recently discovered ribosome-binding protein conserved in eukaryotes. CCDC124 has regulatory functions on the mediation of reversible ribosomal hibernation and translational recovery by direct attachment to large subunit ribosomal protein uL5, 25S rRNA backbone, and tRNA-binding P/A-site major groove. Moreover, it independently mediates cell division and cellular stress response by facilitating cytokinetic abscission and disulfide stress-dependent transcriptional regulation, respectively. However, the structural characterization and intracellular physiological status of CCDC124 remain unknown. In this study, we employed advanced in silico protein modeling and characterization tools to generate a native-like tertiary structure of CCDC124 and examine the disorder, low sequence complexity, and aggregation propensities, as well as high-order dimeric/oligomeric states. Subsequently, dimerization of CCDC124 was investigated with co-immunoprecipitation (CO-IP) analysis, immunostaining, and a recent live-cell protein-protein interaction method, bimolecular fluorescence complementation (BiFC). Results revealed CCDC124 as a highly disordered protein consisting of low complexity regions at the N-terminus and an aggregation sequence (151-IAVLSV-156) located in the middle region. Molecular docking and post-docking binding free energy analyses highlighted a potential involvement of V153 residue on the generation of high-order dimeric/oligomeric structures. Co-IP, immunostaining, and BiFC analyses were used to further confirm the dimeric state of CCDC124 predominantly localized at the cytoplasm. In conclusion, our findings revealed in silico structural characterization and in vivo subcellular physiological state of CCDC124, suggesting low-complexity regions located at the N-terminus of disordered CCDC124 may regulate the formation of aggregates or high-order dimeric/oligomeric states.

Npl3 stabilizes R-loops at telomeres to prevent accelerated replicative senescence.

Telomere shortening rates must be regulated to prevent premature replicative senescence. TERRA R-loops become stabilized at critically short telomeres to promote their elongation through homology-directed repair (HDR), thereby counteracting senescence onset. Using a non-bias proteomic approach to detect telomere binding factors, we identified Npl3, an RNA-binding protein previously implicated in multiple RNA biogenesis processes. Using chromatin immunoprecipitation and RNA immunoprecipitation, we demonstrate that Npl3 interacts with TERRA and telomeres. Furthermore, we show that Npl3 associates with telomeres in an R-loop-dependent manner, as changes in R-loop levels, for example, at short telomeres, modulate the recruitment of Npl3 to chromosome ends. Through a series of genetic and biochemical approaches, we reveal that Npl3 binds to TERRA and stabilizes R-loops at short telomeres, which in turn promotes HDR and prevents premature replicative senescence onset. This may have implications for diseases associated with excessive telomere shortening.

Possums-based parental education for infant sleep: cued care resulting in sustained breastfeeding.

For infants and their families, sleep consolidation is important in maturing neural and circadian rhythms, and in family dynamics. The Possums Infant Sleep Program is a cued care approach to infant sleep, responding to infant cues in a flexible manner, dialing down the infant's sympathetic nervous system. The current study evaluated the effect of the Possums program on infant sleep and breastfeeding in infants (6-12 months) from a well-child outpatient clinic in Turkey, with the program intervention group (n = 91) compared with usual care (n = 92). In total, 157 mother-infant dyads completed the study. Infant sleep and breastfeeding rates were assessed at baseline and after 3 months. Nocturnal wakefulness, daytime sleep duration, naps, and night wakening decreased in both groups. Nocturnal sleep duration and the longest stretch of time the child was asleep during the night increased significantly in both groups without any change in total sleep duration. Night wakening was significantly lower and nocturnal sleep duration was significantly higher in the intervention group. However, mixed effects model analyses indicated no significant differences between the groups on any of the sleep outcomes after adjusting for confounders. Despite this, breastfeeding rates were significantly higher in the intervention group compared with those in the usual care group at follow-up.Conclusion: The Possum infant sleep program provided equivalent positive results on sleep parameters compared to usual care while advocating a more cued response. The critical difference was evident in sustained breastfeeding. What is Known: • Responsive sleep programs produce sleep consolidation, by responding to the infant's cues without ignoring, and then gradually reducing parental interaction. • Breastfeeding to sleep may be considered an undesirable sleep association in some infant sleep interventions. What is New: • The Possums Infant Sleep Program provided equivalent positive results to usual care while advocating a more cued response. • The critical difference was in sustaining breastfeeding, and the program was associated with better breastfeeding rates.

Facile modification of polycaprolactone nanofibers with egg white protein.

Synthetic polymers remain to be a major choice for scaffold fabrication due to their structural stability and mechanical strength. However, the lack of functional moieties limits their application for cell-based therapies which necessitate modification and functionalization. Blending synthetic polymers with natural components is a simple and effective way to achieve the desired biological properties for a scaffold. Herein, nanofibrous mats made of polycaprolactone (PCL) and egg white protein (EWP) blend were developed and further evaluated for use as a scaffold for tissue engineering applications. Homogeneous distribution of EWP was achieved throughout the nanofibrous mats, as shown by immunohistochemistry. ATR-FTIR analysis and contact angle measurements have further confirmed the presence of EWP on the surface of the samples. The swelling test showed that PCL/EWP nanofibers have higher water uptake than PCL nanofibrous mats. Also, EWP addition on the nanofibrous mats resulted in an increase in the tensile strength and Young's modulus of the mats, indicating that the presence of protein can greatly enhance the mechanical properties of the mats. A significantly higher, more uniform, and dispersed cell spreading was observed on days 7 and 14 than that on neat PCL mats, demonstrating the importance of providing the required cues for cell homing by the availability of EWP. Hence, EWP is shown to be a simple and low-cost source for the functionalization of PCL nanofibrous mats. EWP is, therefore, a facile candidate to enhance cellular interactions of synthetic polymers for a wide range of tissue engineering applications.

Fetal Genetic Diagnosis by Chorionic Villus Sampling: Evaluation of the Five-Year Experience from a Single Center.

OBJECTIVE: We summarized our five-year chorionic villus sampling (CVS) experience with indications, detected chromosomal abnormalities and pregnancy outcomes. Materials and Methods: This retrospective study examined 552 patients underwent CVS for prenatal diagnosis between 2014 and 2018. Results: The most frequent patients undergoing CVS indications were abnormal aneuploidy screening results, increased nuchal translucency, and cystic hygroma/edema. Of 552 CVS, 385 were normal, 141 abnormal. Eight were contaminated with maternal cells, 4 were mosaics, in 12 the culture failed, and in 2 there was inadequate sampling. The most frequent chromosomal abnormalities were trisomy 21, trisomy 18 and 45,X. Of 246 followed pregnancies, there were 165 live-births (67,1%), 58 pregnancy terminations (23,6%), and 23 pregnancy losses (9,3%). There were 5 procedure-related losses (2%), 3 of which were chromosomally normal. Conclusion: Although significant advances have been made in noninvasive methods such as NIPT, CVS is still a reliable technique for cytogenetic diagnosis in early gestation.

Identification of novel TUBB1 variants in patients with macrothrombocytopenia.

Background/aim: Macrothrombocytopenia is an autosomal-dominant disorder characterized by increased platelet size and a decreased number of circulating platelets. The membrane skeleton and the link between actin filaments of the skeleton and microtubules, which consist of alpha and beta tubulin [including the tubulin beta-1 chain (TUBB1)] heterodimers, are important for normal platelet morphology, and defects in these systems are associated with macrothrombocytopenia. Materials and methods: In this study, we sequenced the exons of the TUBB1 gene using DNA isolated from the peripheral blood samples of healthy controls (n = 47) and patients with macrothrombocytopenia (n = 37) from Turkey. The TUBB1 expression levels in fractioned blood samples from patients and healthy controls were analyzed by RT-qPCR and Western blot. Microtubule organization of the platelets in the peripheral blood smears of patients, and in mutant TUBB1-transfected HeLa cells, were analyzed by immunofluorescence staining. Results: A new TUBB1 c.803G>T (p.T178T) variant was detected in all of the control and patient samples. Importantly, we found 3 new heterozygous TUBB1 variants predicting amino acid substitutions: G146R (in 1 patient), E123Q (in 1 patient), and T274M (in 4 patients); the latter variant was associated with milder thrombocytopenia in cancer patients treated with paclitaxel. Ectopic expression of TUBB1 T274M/R307H variant in HeLa cells resulted in irregular microtubule organization. Conclusion: Further clinical and functional studies of the newly identified TUBB1 variants may offer important insights into their pathogenicity in macrothrombocytopenia.

Assessment of Mechanical Fetal PR Interval in Intrahepatic Cholestasis of Pregnancy and Its Relationship with the Severity of the Disease.

OBJECTIVE: This study aimed to investigate the fetal atrioventricular conduction system in intrahepatic cholestasis of pregnancy (ICP) by measuring the fetal mechanical PR interval and to explore the significance of predicting the severity of the disease. STUDY DESIGN: Forty pregnant women diagnosed with ICP, classified as severe and mild, and 40 healthy pregnant women participated in the study. Fetal mechanical PR interval was calculated, and fetal mechanical PR interval and neonatal outcome were compared between the groups. The relationship between the mechanical PR interval and the severity of ICP was analyzed. RESULTS: The fetal mechanical PR interval was significantly longer in the ICP group than in the control group (p < 0.005). Likewise, laboratory parameters such as transaminases (alanine aminotransferase [ALT], aspartate aminotransferase [AST]) and total bilirubin levels were significantly higher in the ICP group (p < 0.005).There were no statistically significant differences in the fetal complications. There was a positive correlation between the severity of disease and fetal PR interval. CONCLUSION: A prolonged fetal mechanical PR interval in fetuses of mothers with ICP was demonstrated in this study. It was also shown that there was a positive correlation between fetal PR interval and severity of the disease. The study concluded that fetal mechanical PR interval measurement can be used to predict the severity of disease in ICP.

Can Variable Plasma Volume Alterations Affect the Efficiency of the First Trimester Screening Test?

BACKGROUND: The aim of this study was to assess the effect of plasma volume alteration determined by hematocrit on biochemical parameters of the first trimester screening test. METHODS: Enrolled in this study were 1,424 pregnant women in their first trimester who underwent a first trimester screening test. Fetal Nuchal Trancluciency measurement was obtained by ultrasonographic evaluation. Blood samples were taken for complete blood count, serum free ß-HCG, and PAPP-A between 11 and 14 weeks of gestation. The effect of plasma volume alteration on the screening test was evaluated. Mean corpuscular volume was used to rule out possible iron deficiency anemia. RESULTS: There were 59 women with combined risk > 1/270. Of these 59 women, there were 21 false positive results (1.5%). Serum Htc significantly predicted the false positive cases (AUC: 0.839, p < 0.001). The optimal cutoff value was obtained at a value of 30.2% with 85% sensitivity and 75% specificity. CONCLUSIONS: Our study suggests that the degree of plasma alterations may affect the serum levels of the biochemical components of the first trimester screening test for aneuploidy, thereby leading to false positive test results.

Utility of the modified myocardial performance index in growth-restricted fetuses.

OBJECTIVES: The modified myocardial performance index (Mod-MPI) can be used to assess myocardial function. Fetal growth restriction can affect fetal myocardial function, thereby altering the Mod-MPI. The results of previous studies on the utility of the Mod-MPI in growth-restricted fetuses are conflicting. The aim of this study was to calculate the left modified-MPI in growth-restricted fetuses and to compare the results with those of healthy fetuses. METHODS: This was a prospective cross-sectional case-control study. In total, 40 women with growth-restricted fetuses and 40 women with fetuses of normal weight (controls) at 29-39 gestational weeks were enrolled in the study. An experienced obstetrician calculated the Mod-MPI for each fetus. Women with systemic diseases or fetuses with chromosomal/structural abnormalities were excluded from the study. The results of Mod-MPI measurements of the two groups were compared. RESULTS: The mean single deepest vertical pocket (SDVP) of amniotic fluid, estimated fetal weight (EFW), and isovolumetric relaxation time (IRT) was significantly lower in the fetal growth restriction (FGR) group as compared with these parameters in the control group (P < .05). The uterine artery (UtA) pulsatility index (PI) was significantly higher in the FGR group as compared with that in the control group (P < .05). There were six cases of absent end-diastolic flow (AED) in the FGR group. There were no statistically significant between-group differences in the Mod-MPI, isovolumetric contraction time (ICT), and ejection time (ET) (P > .05). There was also no statistically significant correlation between the Mod-MPI in the fetuses with AED and the control group for Mod-MPI (P > .05). CONCLUSION: The utility of the Mod-MPI in FGR remains unclear. Future studies with larger populations are needed to determine the utility of the Mod-MPI as a predictor of cardiac compromise in FGR.

Chitinases Are Essential for Cell Separation in Ustilago maydis.

Chitin is an essential component of the fungal cell wall, providing rigidity and stability. Its degradation is mediated by chitinases and supposedly ensures the dynamic plasticity of the cell wall during growth and morphogenesis. Hence, chitinases should be particularly important for fungi with dramatic morphological changes, such as Ustilago maydis. This smut fungus switches from yeast to filamentous growth for plant infection, proliferates as a mycelium in planta, and forms teliospores for spreading. Here, we investigate the contribution of its four chitinolytic enzymes to the different morphological changes during the complete life cycle in a comprehensive study of deletion strains combined with biochemical and cell biological approaches. Interestingly, two chitinases act redundantly in cell separation during yeast growth. They mediate the degradation of remnant chitin in the fragmentation zone between mother and daughter cell. In contrast, even the complete lack of chitinolytic activity does not affect formation of the infectious filament, infection, biotrophic growth, or teliospore germination. Thus, unexpectedly we can exclude a major role for chitinolytic enzymes in morphogenesis or pathogenicity of U. maydis. Nevertheless, redundant activity of even two chitinases is essential for cell separation during saprophytic growth, possibly to improve nutrient access or spreading of yeast cells by wind or rain.

Selenoprotein P is not elevated in gestational diabetes mellitus.

Selenoprotein P concentrations have been found to be associated with insulin resistance and elevated in patients with type 2 diabetes mellitus (DM). The aim of the present study was to investigate circulating selenoprotein P level and its possible relationship with metabolic parameters in gestational diabetes mellitus (GDM). Plasma selenoprotein P concentrations were measured in 30 pregnant women with GDM, 35 pregnant women without GDM and 22 healthy nonpregnant women. No difference in selenoprotein P levels was observed among the groups [6.2 (4.5-8.2), 7.9 (4.5-10.7) and 6.7 (5.3-9.1) ng/ml, respectively, p = 0.69]. In pregnant women with and without GDM, selenoprotein P did not correlate with age, gestational age, prepregnancy body mass index (BMI), HbA1c, glucose concentrations at oral glucose tolerance test (OGTT), area under curve (AUC) glucose, total cholesterol, LDL cholesterol and triglycerides levels (p > 0.05). But, there were statistically significant correlations between selenoprotein P and current BMI (r = -0.28, p = 0.04) and HDL cholesterol levels (r = 0.43, p = 0.01). We found that selenoprotein P concentrations are not elevated in women with GDM but associated with BMI and HDL cholesterol.

Improved activity and pH stability of E. coli ATCC 11105 penicillin acylase by error-prone PCR.

Penicillin G acylase is the key enzyme used in the industrial production of ß-lactam antibiotics. This enzyme hydrolyzes penicillin G and related ß-lactam antibiotics releasing 6-aminopenicillanic acid, which is an intermediate in the production of semisynthetic penicillins. To improve the enzymatic activity of Escherichia coli penicillin acylase, sequential rounds of error-prone polymerase chain reaction were applied to the E. coli pac gene. After the second round of evolution, the best mutant M2234 with enhanced activity was selected and analyzed. DNA sequence analyses of M2234 revealed that one amino acid residue (K297I), located far from the center of the catalytic pocket, was changed. This mutant (M2234) has a specific activity 4.0 times higher than the parent enzyme and also displayed higher stability at pH 10.

Development and functionalization of electrospun fiber coated thin film microextraction devices for rapid mass spectrometric determination of biologically important polar molecules.

Rapid diagnosis of diseases is one of the challenging areas in clinical research. From the analytical chemist's perspective, the main challenges are isolating the compounds from the bio-specimen and lengthy analysis times. In this regard, solid phase microextraction offers a platform to address the abovementioned challenges. Moreover, its sharp tip-thin film geometry, known as coated blade spray (CBS), can enhance the extraction and act as an ionization source in direct mass spectrometric analysis. In this study, a new CBS device specifically designed for polar analytes was prepared and optimized to determine urinary metabolites. For this purpose, polyacrylonitrile (PAN) was selected as a base polymer as it can be electrospun to form a nanofibrous structure, and it can be modified with weak ion exchange moieties to interact with polar analytes. Following the electrospinning of PAN, hydrolysis was optimized, and conditions leading to sufficient extraction enhancement without dissolving the polymer were obtained when probes were treated with 5.0 M of NaOH for 2.5 h. Using the coated blades prepared as explained, the evaluation of various extraction conditions showed that 5 min is sufficient for equilibrium extraction. In addition, the solution's ionic strength and pH significantly affect the extraction. Optimum sorption was obtained at no salt added and pH 7.0 conditions. The CBS-MS optimization showed that 10.0 µL of ACN/MeOH/H2O (40:40:20, v/v/v) with formic acid kept for 15 seconds on the blade before voltage application leads to the highest signal. The limits of quantification of the analytes are between 50 and 100 ng/mL.

Live Cell Protein Imaging of Tandem Complemented-GFP11-Tagged Coiled-Coil Domain-Containing Protein-124 Identifies this Factor in G3BP1-Induced Stress-Granules.

Coiled-coil domain-containing 124 protein is a multifunctional RNA-binding factor, and it was previously reported to interact with various biomolecular complexes localized at diverse subcellular locations, such as the ribosome, centrosome, midbody, and nucleoli. We aimed to better characterize the subcellular CCDC124 translocation by labelling this protein with a fluorescent tag, followed by laser scanning confocal microscopy methods. As traditional GFP-tagging of small proteins such as CCDC124 often faces limitations like potential structural perturbations of labeled proteins, and interference of the fluorescent-tag with their endogenous cellular functions, we aimed to label CCDC124 with the smallest possible split-GFP associated protein-tagging system (GFP11/GFP1-10) for better characterization of its subcellular localizations and its translocation dynamics. By recombinant DNA techniques we generated CCDC124-constructs labelled with either single of four tandem copies of GFP11 (GFP11 × 1::CCDC124, GFP11 × 4::CCDC124, or CCDC124::GFP11 × 4). We then cotransfected U2OS cells with these split-GFP constructs (GFP11 × 1(or X4)::CCDC124/GFP1-10) and analyzed subcellular localization of CCDC124 protein by laser scanning confocal microscopy. Tagging CCDC124 with four tandem copies of a 16-amino acid short GFP-derived peptide-tag (GFP11 × 4::CCDC124) allowed better characterization of the subcellular localization of CCDC124 protein in our model human bone osteosarcoma (U2OS) cells. Thus, by this novel methodology we successfully identified GFP11 × 4::CCDC124 molecules in G3BP1-overexpression induced stress-granules by live cell protein imaging for the first time. Our findings propose CCDC124 as a novel component of the stress granule which is a membraneless organelle involved in translational shut-down in response to cellular stress.

A multi-faceted approach to unravel coding and non-coding gene fusions and target chimeric proteins in ataxia.

Ataxia represents a heterogeneous group of neurodegenerative disorders characterized by a loss of balance and coordination, often resulting from mutations in genes vital for cerebellar function and maintenance. Recent advances in genomics have identified gene fusion events as critical contributors to various cancers and neurodegenerative diseases. However, their role in ataxia pathogenesis remains largely unexplored. Our study Hdelved into this possibility by analyzing RNA sequencing data from 1443 diverse samples, including cell and mouse models, patient samples, and healthy controls. We identified 7067 novel gene fusions, potentially pivotal in disease onset. These fusions, notably in-frame, could produce chimeric proteins, disrupt gene regulation, or introduce new functions. We observed conservation of specific amino acids at fusion breakpoints and identified potential aggregate formations in fusion proteins, known to contribute to ataxia. Through AI-based protein structure prediction, we identified topological changes in three high-confidence fusion proteins-TEN1-ACOX1, PEX14-NMNAT1, and ITPR1-GRID2-which could potentially alter their functions. Subsequent virtual drug screening identified several molecules and peptides with high-affinity binding to fusion sites. Molecular dynamics simulations confirmed the stability of these protein-ligand complexes at fusion breakpoints. Additionally, we explored the role of non-coding RNA fusions as miRNA sponges. One such fusion, RP11-547P4-FLJ33910, showed strong interaction with hsa-miR-504-5p, potentially acting as its sponge. This interaction correlated with the upregulation of hsa-miR-504-5p target genes, some previously linked to ataxia. In conclusion, our study unveils new aspects of gene fusions in ataxia, suggesting their significant role in pathogenesis and opening avenues for targeted therapeutic interventions.Communicated by Ramaswamy H. Sarma.

A Critical Study on the Potential of Solid-Phase Fluorescence Spectroscopy (SPFS) in Quantitative Analysis: Effect of Solid Diluent and Sampling Method on Signal Quality.

BACKGROUND: Solid-phase fluorescence spectroscopy (SPFS) is a very useful non-destructive technique for directly analyzing samples in solid form without the use of solvents. However, due to the so-called inner-filter effect, it is sometimes necessary to dilute solid samples using non-fluorescent solids as diluents. OBJECTIVE: This study aimed to explore the potential of SPFS in the quantitative analysis of fluorescent species based on: (1) the type of solid diluent; and (2) the sampling method used in the SPFS analysis. METHODS: Four different solids were used as solid diluents in the preparation of standard mixtures having different concentrations of rhodamine b and fluorescein as model compounds. Standard mixtures of model compounds were sampled by two different methods called: (1) the powder-cell method; and (2) the adhesive tape method. LOQ and calibration sensitivity calculated from the calibration graphs were used to assess the measurement performance. The usability of SPFS in real-sample analyses was also evaluated in detail. RESULTS: Among the solid diluents studied, the best results were obtained with sodium carbonate. The powder-cell method yielded a significant advantage over the adhesive tape method. The lowest LOQs for rhodamine b and fluorescein were obtained by sodium carbonate and the powder-cell method as 0.06 and 0.11 mg/kg, respectively. The results of real-sample analyses were verified using conventional liquid-phase fluorescence spectroscopy (LPFS). CONCLUSION: Solid-diluent type and sampling method were found to affect the performance of the SPFS technique. A combination of sodium carbonate and the powder-cell method gave the best results. According to the t-test, no difference was observed between the means obtained by SPFS and LPFS techniques in real-sample analyses. HIGHLIGHTS: In SPFS, toxic organic solvents and difficult sample preparation steps are not required. This makes the method advantageous over conventional fluorescence analyses performed in the liquid phase.

An experimental study on the environmental impact of hydrogen and natural gas blend burning.

In this study, an experimental investigation is conducted to analyze the effect of adding hydrogen into natural gas on emissions and the burning performance of the obtained blends. Natural gas alone and natural gas-hydrogen blends are burned in identical gas stoves, and the emitted CO, CO2, and NOx are measured. The base case with natural gas only is compared with the natural gas and hydrogen blends (including hydrogen additions of 10%, 20% and 30% volumetrically). The experimental results show that the combustion efficiency increases from 39.32% to 44.4% by enhancing the hydrogen blending ratio from 0 to 0.3. While CO2 and CO emissions are reduced with rising the hydrogen ratio in the blend, NOx emissions have a fluctuating trend. Moreover, a life cycle analysis is performed to determine the environmental impact of the considered blending scenarios. With the blending ratio of 0.3 hydrogen by volume, global warming potential decreases from 6.233 to 6.123 kg CO2 equivalents per kg blend, and acidification potential reduces from 0.0507 to 0.04928 kg SO2 equivalents per kg blend in comparison with natural gas. On the other hand, human toxicity, abiotic depletion, and ozone depletion potentials per kg blend show slight augmentation from 5.30 to 5.52 kg 1,4-dichlorobenzene (DCB) eq., 0.0000107 to 0.00005921 kg SB eq., and 3.17 × 10-8 to 5.38 × 10-8 kg CFC-11 eq., respectively.