Clostridioides difficile is the most important pathogen causing antimicrobial-associated diarrhea and has recently been recognized as a cause of community-associated C. difficile infection (CA-CDI). This study aimed to characterize virulence factors, antimicrobial resistance (AMR), ribotype (RT) distribution and genetic relationship of C. difficile isolates from diverse fecally contaminated environmental sources. C. difficile isolates were recovered from different environmental samples in Northern Germany. Antimicrobial susceptibility testing was determined by E-test or disk diffusion method. Toxin genes (tcdA and tcdB), genes coding for binary toxins (cdtAB) and ribotyping were determined by PCR. Furthermore, 166 isolates were subjected to whole genome sequencing (WGS) for core genome multi-locus sequence typing (cgMLST) and extraction of AMR and virulence-encoding genes. Eighty-nine percent (148/166) of isolates were toxigenic, and 51% (76/148) were positive for cdtAB. Eighteen isolates (11%) were non-toxigenic. Thirty distinct RTs were identified. The most common RTs were RT127, RT126, RT001, RT078, and RT014. MLST identified 32 different sequence types (ST). The dominant STs were ST11, followed by ST2, ST3, and ST109. All isolates were susceptible to vancomycin and metronidazole and displayed a variable rate of resistance to moxifloxacin (14%), clarithromycin (26%) and rifampicin (2%). AMR genes, such as gyrA/B, bla_CDD-1/2, aph(3′)-llla-sat-4-ant(6)-la cassette, ermB, tet(M), tet(40), and tetA/B(P), conferring resistance toward fluoroquinolone, beta-lactam, aminoglycoside, macrolide and tetracycline antimicrobials, were found in 166, 137, 29, 32, 21, 72, 17, and 9 isolates, respectively. Eleven “hypervirulent” RT078 strains were detected, and several isolates belonged to RTs (i.e., RT127, RT126, RT023, RT017, RT001, RT014, RT020, and RT106) associated with CA-CDI, indicating possible transmission between humans and environmental sources pointing out to a zoonotic potential.

Derivative-free optimization techniques are widely used for solving optimization problems. The

focus in this work is given to some variants of Nelder-Mead and particle swarm methods to tackle two

unconstrained optimization problems originated from optimal control, namely the pole assignment problem for

discrete and continuous-time positive systems. we present the Nelder-Mead and Particle Swarm optimization

methods to solve problems. Moreover comparing our results with benchmarks in the literature.

The extremely high speed offered by UWB systems allows the guard band to be extended to 100% instead of maximum of 25% as in broadband systems. This particular guard ensures this channel is completely free of spurious signals before transmitting next symbol. In this paper, the performance of non block transmission frequency domain UWB receiver with changeable zero-padding is presented. The receiver can be an alternate to Rake receivers, since clustering effect, common in UWB signals makes Rake receivers impractical and imposes low complexity rake receivers that are not optimum, either.

Biosynthesis techniques have a number of advantages over other methods for producing silver nanoparticles (AgNPs), which provide a wide range of applications. The present work highlights the biosynthesis of AgNPs by mixing pear leaf aqueous extract with silver nitrate, and the formation of AgNPs was observed by the change of mixture color from yellow to dark brown and visible spectrophotometry. Moreover, the effect of pH, reaction time, AgNO3 concentration, extract volume and temperature on the suggested approach was also studied. The results showed that pear leaf aqueous extract is an excellent material for the biosynthesis of AgNPs, and by controlling the mentioned parameters that influence synthesis, a large number of AgNPs with small sizes may be produced.

Biosynthesis techniques have a number of advantages over other methods for producing silver nanoparticles (AgNPs), which provide a wide range of applications. The present work highlights the biosynthesis of AgNPs by mixing pear leaf aqueous extract with silver nitrate, and the formation of AgNPs was observed by the change of mixture color from yellow to dark brown and visible spectrophotometry. Moreover, the effect of pH, reaction time, AgNO3 concentration, extract volume and temperature on the suggested approach was also studied. The results showed that pear leaf aqueous extract is an excellent material for the biosynthesis of AgNPs, and by controlling the mentioned parameters that influence synthesis, a large number of AgNPs with small sizes may be produced. Keywords: silver nitrate, silver nanoparticles, pear leaves, biosynthesis 

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This study reports a rapid and eco-friendly green method for the synthesis of silver nanoparticles from silver nitrate solution using winter jasmine leaves extract as a reducing agent of Ag+ to Ag0. A visible Absorption Spectrophotometer was used to monitor the formation of silver nanoparticles (AgNPs). The visible spectrum showed an absorption peak at 420 nm which reflects the surface plasmon resonance (SPR) of AgNPs. In addition to that, the synthesis of AgNPs was confirmed by the color change of the solution. By studying the most important factors affecting the formation of AgNPs, it was noted that the productivity of AgNPs in the solution increased by increasing the pH of the solution, and the basic medium was the appropriate medium for the synthesis process. Also, the amount of produced AgNPs increased with the increase in temperature, volume of extract, reaction time, the extract volume ratio of the winter jasmine leaves, and silver nitrate concentration. In conclusion, the aqueous extract of winter jasmine leaves represents a suitable material for the biosynthesis of AgNPs, and large amounts of AgNPs with appropriate sizes may be obtained by controlling the parameters that affect the synthesis process.

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Clostridioides difficile (C. difficile) is the most common pathogen causing antibiotic-associated intestinal diseases in humans and some animal species, but it can also be present in various environments outside hospitals. Thus, the objective of this study was to investigate the presence and the characteristics of toxin-encoding genes and antimicrobial resistance of C. difficile isolates from different environmental sources. C. difficile was found in 32 out of 81 samples (39.50%) after selective enrichment of spore-forming bacteria and in 45 samples (55.56%) using a TaqMan-based qPCR assay. A total of 169 C. difficile isolates were recovered from those 32 C. difficile-positive environmental samples. The majority of environmental C. difficile isolates were toxigenic, with many (88.75%) positive for tcdA and tcdB. Seventy-four isolates (43.78%) were positive for binary toxins, cdtA and cdtB, and 19 isolates were non-toxigenic. All the environmental C. difficile isolates were susceptible to vancomycin and metronidazole, and most isolates were resistant to ciprofloxacin (66.86%) and clindamycin (46.15%), followed by moxifloxacin (13.02%) and tetracycline (4.73%). Seventy-five isolates (44.38%) showed resistance to at least two of the tested antimicrobials. C. difficile strains are commonly present in various environmental sources contaminated by feces and could be a potential source of community-associated C. difficile infections.

Abstract: Earth velocity changes under many reasons. They cause variations in the length of daytime. These reasons are; interior changes, which usually occur during events that tend to speed up Earth’s rotation slightly but noticeably, and Outward changes, where material that was typically at one point at a higher elevation on Earth surface falls down to be at a lower point. The first reason may show in several figures like earthquake and condensing core of earth. On the other hand, tide, melting glacier poles, and changing weather they cause the other reason. The amount of time that increasing or decreasing in a day until now do not exceed few seconds, but on the massive scale of time as the age of earth it becomes important value.