Browse

You are looking at 1 - 10 of 83,471 items for

  • Refine by Access: All Content x
Clear All

In this paper, some basic characterizations of a weighted Bloch space with the differentiable strictly positive weight ūĚúĒ on the unit disc are given, including the growth, the higher order or free derivative descriptions, and integral characterizations of functions in the space.

Open access

Abstract

Due to the relative independence from the operational parameters, the linear retention indices (LRIs) are useful tool in gas chromatography-mass spectrometry (GC-MS) qualitative analysis. The aim of the current study was to develop a multiple linear regression (MLR) model for the prediction of LRIs as a function of selected molecular descriptors. Liquid injection GC-MS was used for the analysis of Essential oils (Rose, Lavender and Peppermint) separating the ingredients by a semi-standard non-polar stationary phase. As a result, a sum of 103 compounds were identified and their experimental LRIs were derived relying on reference measurements of a standard mixture of n-alkanes (from C8 to C20). As a next step, a set of molecular descriptors was generated for the distinguished chemical structures. Further, a stepwise MLR was applied for the selection of the significant descriptors (variables) which can be used to predict the LRIs. From an exploit set of over 2000 molecular descriptors, it was found that only 16 can be regarded as significant and independent variables. At this point split validation was applied: the identified compounds were randomly divided into training (85%) and validation (15%) sets. The training set (87 compounds) was used to derive two MLR models by applying i) the ‚Äėenter‚Äô algorithm¬†(R 2 = 0.9960, RMS–ē = 17) and ii) the ‚Äėstepwise‚Äô one (R 2 = 0.9958, RMS–ē = 17). The¬†predictive power was assessed by the validation set (16 compounds) as follows i) q2 F1 = 0.9896, RMSE = 25 and ii) q2 F1 = 0.9886, RMSE = 26, respectively. The adequateness of both regression approaches was further evaluated. Newly developed headspace-solid phase microextraction (HS-SPME) procedures in combination with GC-MS were used for an alternative analysis of the studied Essential oils. Twelve additional compounds, not previously detected by the liquid sample introduction mode of analysis, were identified for which the values of the significant descriptors were within the working range of the developed MLRs. For the last compounds, the LRIs were calculated and the experimental data was used as an external set for assessment of the regression models. The predictive power for both¬†regression approaches was assessed as follows: Enter RMSE = 41, q2 F2 = 0.9503 and Stepwise RMSE = 40, q2 F2 = 0.9521.

Open access

Abstract

The purpose of the present study was to investigate the phenolic profile, antioxidant capacity, and biological activity of Inula helenium subsp. pseudohelenium extracts, for the first time. Phenolic substances in leaf ethanol (L-EtOH), leaf pure water (L-PW), root ethanol (R-EtOH), and root pure water (R-PW) extracts of I. helenium subsp. pseudohelenium plant were investigated by HPLC. Also, the antimicrobial (hollow agar), antioxidant, antiproliferative, and DNA protective activities of the samples were examined in vitro. Gallic acid was not detected in the extracts, the presence of curcumin was detected only in EtOH extracts. L-EtOH exhibited the best antimicrobial activity. According to the antioxidant results, the L-EtOH extract had an activity profile close to the standard antioxidants in general. It was also found that the L-EtOH extract stabilised the DNA by disrupting the scavenging effect of H2O2+DMSO. According to the antiproliferative activity results, EtOH extracts exhibited the strongest effect, especially against MCF7 cancer cell lines. When evaluated in general terms, it was found that L-EtOH extract showed better activity than other extracts. It is important to conduct more in vivo and in vitro studies after isolating the active components of extracts e.g. L-EtOH, which have good effects in terms of biological activity.

Restricted access
Acta Microbiologica et Immunologica Hungarica
Authors:
Maria Chatzidimitriou
,
Asimoula Kavvada
,
Dimitrios Kavvadas
,
Maria Anna Kyriazidi
,
Konstantinos Eleftheriadis
,
Sotirios Varlamis
,
Vassilis Papaliagkas
, and
Stella Mitka

Abstract

Carbapenems are considered to be among the last line antibiotics against extended-spectrum ő≤-lactamase producing Enterobacterales. Carbapenem-resistant Klebsiella pneumoniae (CRKP) has been frequently reported and its spread in Europe is indisputable and poses an enormous threat to hospitalized patients which is of growing concern. This review aims to record prevalence of CRKP in the Balkan region and to review the current knowledge about this life-threatening pathogen. In this review, we summarize data about clinical isolates of carbapenem-resistant K. pneumoniae from Greece, Croatia, Romania, Bulgaria, Serbia, Slovenia, Montenegro, Bosnia-Herzegovina and Albania from published reports between 2000 and 2023. Among Balkan countries, Greece and Romania are the ones with the most reports about CRKP. Since 2007, KPCs are the dominant carbapenemases in both countries. KPC-2 and NDM-1-producing K. pneumoniae strains have been identified as the most frequent CRKP in Croatia, Bulgaria, Serbia, and Slovenia. OXA-48 enzyme has been identified in most Balkan countries. In addition, since 2018, CRKP sequence type 11 (ST11) seems to have replaced ST258 in Balkan Peninsula, while ST15 continues to thrive throughout the years. Not only efficacy of colistin against CRKP has decreased dramatically during the last ten years but colistin resistance mechanism is based on alterations of chromosomal mgrB gene, rather than the already known mcr genes.

Moreover, ceftazidime-avibactam-resistant CRKP were detected mostly in Greece. Emergence of CRKP poses a severe threat to the Balkan countries. Due to the narrow therapeutic window, it is essential to prevent the spread of multiresistant K. pneumoniae strains.

Open access

Abstract

Carbapenem resistant Enterobacteriaceae (CRE) are major human pathogens because, these cause high number of difficult-to-treat infections. Allogeneic hematopoietic stem cell transplant (AHSCT) recipients are highly exposed to these type of bacteria. The aim of our study was to investigate prevalence of CRE colonization in AHSCT patients and to determine genes encoding carbapenem resistance. A¬†retrospective study conducted between January 2015 and December 2019, involved 55 patients colonized with CRE strains. We determined the rate of antibiotic resistance according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the carbapenem resistance genes by PCR assays for genes encoding most frequent ő≤-lactamases namely, bla GES , bla KPC , bla IMI , bla NDM , bla VIM , bla IMP and bla OXA-48. Eighty-one episodes of CRE colonization were recorded in 55 patients, mainly suffering from acute leukaemia (30%) and aplastic anemia (26%). History of hospitalization was noted in 80 episodes. Prior antibiotic treatment, severe neutropenia and corticosteroid therapy were respectively found in 94%, 76% and 58% of cases. Among the 55 patients, six patients (11%) developed a CRE infection. The CRE responsible for colonization were carbapenemase producers in 90% of cases. They belonged mostly to Klebsiella pneumoniae (61/81) and Escherichia coli species (10/81). Antibiotic resistance rates were 100% for ertapenem, 53% for imipenem, 42% for amikacin, 88% for ciprofloxacin and 27% for fosfomycin. Molecular study showed that bla OXA-48 gene was the most frequent (60.5%), followed by bla NDM (58%). Thirty-five (43%) strains were co-producers of carbapenemases. In our study, we report a high rate of CRE intestinal colonization in AHSCT recipients of our center.

Restricted access

Abstract

During the coronavirus disease 2019 (COVID-19) pandemic, artificial intelligence (AI) based software on chest computed tomography (CT) imaging has proven to have a valuable role in accelerating diagnosis and screening. The proposed AI-based tools proved to be rapid and reproducible techniques to guide patient management and treatment protocols. Although no specific guidelines exist, CT-imaging and clinical features are used for patient staging. To shed light on the role of AI techniques that have been developed in fighting COVID-19, in this review, studies investigating the usage of commonly used AI models on chest CT imaging for disease quantification and prognostication are collected.

Open access

Abstract

Local scour poses a grave threat to bridge foundations, potentially causing catastrophic collapses. This study uses FLOW-3D with the Reynolds-Averaged Navier-Stokes model to analyze pier scour and dune formation under bridges. It focuses on submerged debris shapes near the water's surface. Results closely match experiments when specific conditions are met. The study introduces an innovative approach to debris impact assessment. Instead of traditional methods, it proposes a novel equation accounting for debris's effective area and elevation. This enhances reliability by over 20%, improving scour depth assessment in debris-laden scenarios. This advances the understanding of debris's role in local scour, benefiting bridge design and management practices.

Open access

Abstract

As a byproduct from the deep processing of longan fruit, longan kernel is rich in starch and is a good source for starch production. In this study, the rheological properties of longan kernel starch (LS) extracted by protease-assisted alkali method were investigated. When the shear rate was from 1 to 100 s‚ąí1, the pastes containing 4%‚Äď7% (w/v) of LS showed a non-Newtonian fluid with a pseudoplastic fluid characteristic. Their shear stress, apparent viscosity, complex viscosity, storage modulus (G‚Ä≤), and loss modulus (G‚Ä≥) positively correlated with starch concentration. The loss factor (tan őī) of all LS pastes was less than 1. At same concentration, LS paste showed a stronger pseudoplastic fluid characteristic and higher elasticity than corn starch and pea starch pastes. Based on this, LS has potential in processing of jelly, soft sweets, ham sausage, and some other sauces.

Restricted access

Abstract

The biceps is one of the most important muscles of the flexor compartment of the arm. Recently there has been an increase in the global reported incidence of biceps tendon rupture worldwide. Generally, tears are seen in the elderly population and are precipitated due to underlying risk factors. Diagnosis is done with a combination of clinical findings and ultrasonography. We report a case of a 60-year-old female without any underlying risk factors who presented with nontraumatic spontaneous rupture of the right biceps tendon.

Open access

Abstract

Monitoring benzoylphenylureas (BPUs) residues in ready-to-eat vegetables is of great interest for an adequate assessment of human pesticide exposure. A rapid, inexpensive, simple, and effective method for determining 8 BPUs insecticides in tomatoes and cucumbers was developed and validated. Vortex-assisted liquid-liquid extraction (VA-LLE) followed by dispersive solid-phase extraction (d-SPE) using graphitized carbon black (GCB) for cleanup was used before LC-MS/MS analysis. Different parameters were optimized, including the type and volume of extractants, vortex time, and the type and amount¬†of¬†adsorbents used for cleanup. The evaluation showed that the method has excellent linearity (R 2 ‚Č• 0.994). The recovered 8 BPUs insecticides from spiked tomato and cucumber samples at 0.01,¬†0.05, and 0.25‚ÄČmg kg‚ąí1 ranged from 83.2 to 105.2%, with RSD of 4.9‚Äď14.6%. The limits of quantitation (LOQs) were 0.0025‚ÄČmg kg‚ąí1 (0.005‚ÄČmg kg‚ąí1 for lufenuron). Within-day repeatability ranged from 3.9 to 13.9%, while between-day repeatability ranged from 8.9% to 17.7%. The optimized method was used to analyze 100 samples of tomatoes and cucumbers marketed in Saudi Arabia.

Open access