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Abstract

Thermomechanical treatments and variations in chemical composition during the production of these alloys allow their properties to be adjusted as necessary. In the present research, the influence of chemical modification was analyzed by adding a combination of two rare earth elements (lanthanum and cerium) and performing a pretreatment before natural and artificial aging. With this, it was observed that said chemical modification led to an increase in hardness after artificial aging and specific suppression of the hardening speed at room temperature, combined with a pretreatment process to improve the density of the nucleation site and take advantage of the possible vacancy capture effect. Furthermore, microstructural changes were observed in the study alloys by scanning electron microscopy. The above allows the design of alloy production processes according to the requirements of each application.

Open access

Abstract

Pseudomonas aeruginosa has been in the center of attention for several years as an opportunistic human pathogen implicated in many severe acute and chronic infections particularly in immunocompromised patients. Its high persistence and resistance against many antimicrobial agents are mostly attributed to biofilm formation. Biofilms are microbial communities mainly consisting of extracellular polymeric substances that encapsulate bacteria together and protect them from extracellular stresses. This cell aggregation is a stress response that P. aeruginosa employes as a survival strategy during growth with the toxic detergents. This process has shown to involve several operons such as psl, pel, and alg. Here we used P. aeruginosa strain PAO1 in control group, 40 P. aeruginosa strains from sink and 40 strains from surface of public places. Biofilm formation and gene expression were measured before and after exposure to sub minimum inhibitory concentration (sub-MIC) of biocides chlorhexidine diacetate and benzalkonium chloride. The qRT-PCR and biofilm formation results demonstrated an increase in biofilm formation ability and gene expression of pslA/B and pelA/B in two groups collected from sink and surface in contrast to the control group. A remarkable increase was observed in the biofilm formation and expression of pslA in the bacterial strain collected from the sink after exposure to biocides chlorhexidine diacetate. Both Pel and Psl appeared to have redundant functions as structural scaffolds in biofilms. Sub-MIC levels of detergents can improve biofilm formation ability of P. aeruginosa and therefore trigger resistance.

Restricted access

A positive integer d = i = 1 r p i d i is said to be an exponential divisor or an e-divisor of n = i = 1 r p i n i > 1 if 𝑑𝑖 ∣ 𝑛𝑖 for all prime divisors 𝑝𝑖 of 𝑛. In addition, 1 is an e-divisor of 1. It is easy to see that ℤ+ is a poset under the e-divisibility relation. Utilizing this observation we show that e-convolution of arithmetical functions is an example of the convolution of incidence functions of posets. We also note that the identity, units and the Möbius function are preserved in this process.

Open access

Let (𝑃𝑛)𝑛≥0 and (𝑄𝑛)𝑛≥0 be the Pell and Pell–Lucas sequences. Let 𝑏 be a positive integer such that 𝑏 ≥ 2. In this paper, we prove that the following two Diophantine equations 𝑃𝑛 = 𝑏𝑑𝑃𝑚 + 𝑄𝑘 and 𝑃𝑛 = 𝑏𝑑𝑄𝑚 + 𝑃𝑘 with 𝑑, the number of digits of 𝑃𝑘 or 𝑄𝑘 in base 𝑏, have only finitely many solutions in nonnegative integers (𝑚, 𝑛, 𝑘, 𝑏, 𝑑). Also, we explicitly determine these solutions in cases 2 ≤ 𝑏 ≤ 10.

Open access
Society and Economy
Authors:
Srdana Táborosi
,
Jelena Rajković Avdija
,
Jasmina Poštin
,
Edit Terek Stojanović
,
Nemanja Berber
, and
Milan Nikolić

Abstract

The paper presents the results of research on the impact of national culture, Big Five personality traits, and emotional intelligence on job satisfaction in teleworkers. The impacts were also examined in conventionally employed, which enabled a comparison. The research was conducted in the countries of the Western Balkans and included 313 respondents. The job satisfaction of teleworkers is most positively influenced by humane orientation, performance orientation, agreeableness, conscientiousness, openness, self-regulation, and social skills. Self-awareness can act both positively and negatively, and neuroticism has a negative impact on job satisfaction. National culture has a greater impact on job satisfaction among conventionally employed rather than within teleworkers. Big Five personality traits work differently: extroversion has a greater impact on job satisfaction among conventionally employed, while agreeableness and conscientiousness have a greater impact on job satisfaction among teleworkers. Emotional intelligence has a greater impact on job satisfaction among conventionally employed rather than teleworkers. Teleworking employees are less influenced by the environment, and thus less influenced by national culture. Emotional intelligence helps conventionally employed work more, while teleworkers place higher value on the results of their work.

Open access

Abstract

During the past years, we found a new Coleophora taxon in Hungary that proved to be unknown for the fauna of the country. We identified the unknown specimens using combined information from morphological examination including the female genitalia and genetic analyses. We sequenced the Cytochrome Oxidase “COI” gene of the mitochondrial DNA, and used the resultant base-pair sequence for species identification, using the BOLD platform, and for preparing a phylogenetic tree with the most closely related taxa involved. Our results show that larval and adult morphology, genitalia structure, and the sequence of the COI region of the unknown specimens are most similar to those of Coleophora gazella Toll, 1952. The habitats of the species in Hungary are strongly isolated from the nearest population in Turkey (Anatolia). We also studied habitat characteristics and life history of the species, which are briefly presented in this paper. The article contains four figures and two tables.

Open access

Abstract

A new subgenus of leaf-beetles Chrysolina (Ambrostomima subgen. nov.) is described from Hengduan Mountains (Sichuan and Gansu, China). It is characterized by the following main characters: body metallic, mostly green mixed with purple or one-colored green; last maxillary palpomere elongate, narrow, similar in both sexes; elytral punctures arranged in more or less distinct rows or mostly irregular; elytral epipleura inclined outside; hind wings completely missing; pygidium without furrow in apical 1/2 in most species; tarsomeres 1–3 more or less broadened in male, narrow in female, with entire sole in both sexes.

The subgenus consists of 25 species: Chrysolina amica Lopatin, Ch. baimana Lopatin, Ch. davidiani Lopatin, Ch. korotjaevi Lopatin, Ch. luyoui Daccordi et Ge, Ch. matruelis Lopatin, Ch. mirabilis (Daccordi), Ch. nesterovae Lopatin, Ch. pingchuana Lopatin, Ch. purpureoviridis Lopatin, Ch. rotundata Lopatin, Ch. sichuanica Lopatin, Ch. sicieni Ge et Yang, Ch. songpana Lopatin, Ch. viridiopaca Lopatin, Ch. aurita sp. nov., Ch. auriviridis sp. nov., Ch. bellissima sp. nov., Ch. ferdinandoi sp. nov., Ch. korolevi sp. nov., Ch. latipes sp. nov., Ch. ovata sp. nov., Ch. pilula sp. nov., Ch. pulchra sp. nov., and Ch. tortilla sp. nov.

Types of all previously described species except Ch. luyoui are examined. Males of Ch. mirabilis and Ch. viridiopaca are examined and described for the first time. Key to species is compiled. Type localities of Ch. viridiopaca and Ch. songpana are corrected. Photographs of habitus and male aedeagi are presented for all species.

Open access

As many world languages, Turkic also has simple suffixes in terms of structure, as well as complex suffixes with controversial origins. Although some of these suffixes have been systematized and bound to certain rules, the emergence of some suffixes still remains a mystery. Old Uyghur, which is one of the historical periods of the Turkic language, has such an undeciphered suffix. The compound suffix of +DXrtI has been evaluated by some researchers to date; however, no definite conclusion has been reached regarding its origin and function. For this purpose, various structures in Altaic languages will be examined and a connection will be made between this suffix and the ‘extraordinary’ examples seen in Old Uyghur.

Restricted access