The numerical analysis of cantilever beam structures filled using aluminium foam

KEGA 009STU-4/202

Effect of pre-stress on modification of modal properties of planar structures

The work has been supported by the following research projects VEGA 1/0796/20 and KEGA 009STU-4/2021

Determination of optimal parameters for rapid prototyping of the involute gears

Nowadays, rapid prototyping technologies are available at very affordable prices. This is the main reason why they are being used in almost all industry sectors. 3D printers are currently being widely used for rapid prototyping and development of the new products. However, taking into account the permanent progress of rapid prototyping materials mechanical characteristics (usually different kinds of plastics), 3D printers are sometimes used even for production of the failed parts replacements - operating at the low load and rotational speed conditions. This is the main goal of this paper - to establish optimal 3D printing parameters (printing direction, layer height and percent of infill) which will allow printed gears to replace failed steel gears, for at least some time, enough for spare steel gears to be produced and delivered on site. Taking into account previously mentioned facts, the application of the 3D printed gears can potentially provide the reduction of maintenance delays in different industrial facilities (factories, workshops, etc.) which will consequently lead to significant energy and financial savings

Determination of optimal parameters for rapid prototyping of the involute gears

Nowadays, rapid prototyping technologies are available at very affordable prices. This is the main reason why they are being used in almost all industry sectors. 3D printers are currently being widely used for rapid prototyping and development of the new products. However, taking into account the permanent progress of rapid prototyping materials mechanical characteristics (usually different kinds of plastics), 3D printers are sometimes used even for production of the failed parts replacements - operating at the low load and rotational speed conditions. This is the main goal of this paper - to establish optimal 3D printing parameters (printing direction, layer height and percent of infill) which will allow printed gears to replace failed steel gears, for at least some time, enough for spare steel gears to be produced and delivered on site. Taking into account previously mentioned facts, the application of the 3D printed gears can potentially provide the reduction of maintenance delays in different industrial facilities (factories, workshops, etc.) which will consequently lead to significant energy and financial savings

'20 days protected learning' - students' experiences of an Overseas Nurses Programme - 4 years on: A retrospective survey

Background From September 2005 the Nursing and Midwifery Council (NMC) introduced new arrangements for the registration of non-EU overseas nurses which requires all applicants to undertake '20 days of protected learning' time in the UK and for some, a period of supervised practice. A survey was undertaken at Bournemouth University, which offers a '20 days protected learning only' programme, to elicit overseas nurses' demographic details, experiences in completing the programme and their 'final destinations' once registered. Methods An online survey was devised which contained a mixture of tick box and open ended questions which covered demographic details, views on the programme and final destinations This was uploaded to www.SurveyMonkey.com and sent out to nurses who had completed the Overseas Nurses Programme (ONP) with Bournemouth University (n=1050). Quantiative data were analysed using descriptive statistics and the qualitative data were coded and analysed using content analysis . Results There were 251 respondents (27.7% response rate). The typical 'profile' of a nurse who responded to the survey was female, aged 25-40 years and had been qualified for more than 5 years with a bachelors degree. The majority came from Australia on a 2 year working holiday visa and the key final destination in the UK, on registration with the NMC, was working for an agency. There were five key findings regarding experience of the programe. Of those surveyed 61.2% did not feel it necessary to undergo an ONP; 71.6% felt that they should be able to complete the programme on-line in their own country; 64.2% that the ONP should only contain information about delivery of healthcare in UK and Legal and professional (NMC) issues; 57% that European nurses should also undergo the same programme and sit an IELTS test; and 68.2% that the programme was too theory orientated; and should have links to practice (21%). Conclusions The NMC set the admissions criteria for entry to the register and Standards for an ONP. The findings of this survey raise issues regarding the percieved value and use of this approach for overseas nurses, and it may be helpful to take this into account when considering future policy

Evaluation of acidogenesis products’ effect on biogas production performed with metagenomics and isotopic approaches

Background: During the acetogenic step of anaerobic digestion, the products of acidogenesis are oxidized to substrates for methanogenesis: hydrogen, carbon dioxide and acetate. Acetogenesis and methanogenesis are highly interconnected processes due to the syntrophic associations between acetogenic bacteria and hydrogenotrophic methanogens, allowing the whole process to become thermodynamically favorable. The aim of this study is to determine the influence of the dominant acidic products on the metabolic pathways of methane formation and to find a core microbiome and substrate-specific species in a mixed biogas-producing system. Results: Four methane-producing microbial communities were fed with artificial media having one dominant component, respectively, lactate, butyrate, propionate and acetate, for 896 days in 3.5-L Up-flow Anaerobic Sludge Blanket (UASB) bioreactors. All the microbial communities showed moderately different methane production and utilization of the substrates. Analyses of stable carbon isotope composition of the fermentation gas and the substrates showed differences in average values of δ13C(CH4) and δ13C(CO2) revealing that acetate and lactate strongly favored the acetotrophic pathway, while butyrate and propionate favored the hydrogenotrophic pathway of methane formation. Genome-centric metagenomic analysis recovered 234 Metagenome Assembled Genomes (MAGs), including 31 archaeal and 203 bacterial species, mostly unknown and uncultivable. MAGs accounted for 54%–67% of the entire microbial community (depending on the bioreactor) and evidenced that the microbiome is extremely complex in terms of the number of species. The core microbiome was composed of Methanothrix soehngenii (the most abundant), Methanoculleus sp., unknown Bacteroidales and Spirochaetaceae. Relative abundance analysis of all the samples revealed microbes having substrate preferences. Substrate-specific species were mostly unknown and not predominant in the microbial communities. Conclusions: In this experimental system, the dominant fermentation products subjected to methanogenesis moderately modified the final effect of bioreactor performance. At the molecular level, a different contribution of acetotrophic and hydrogenotrophic pathways for methane production, a very high level of new species recovered, and a moderate variability in microbial composition depending on substrate availability were evidenced. Propionate was not a factor ceasing methane production. All these findings are relevant because lactate, acetate, propionate and butyrate are the universal products of acidogenesis, regardless of feedstock

Влияние химической структуры карбоксилсодержащих полимеров на морфологию осадков и устойчивость дисперсий карбонатов

The influence of the molecular structure of carboxyl-containing polymers on their inhibitory and stabilizing effect in the precipitation processes was studied using a number of polymeric acids with different contents of carboxyl groups (X): polyacrylic acid (Mn = 5100 g-mol–1, X = 61.11 %), polymethacrylic acid (Mn = 5500 g-mol–1, X = 48.79 %), copolymer of methacrylic acid with turpentine terpene (α-pinene) (Mn = 350 g-mol–1, X = 14.54 %). It has been established that polyacid molecules slow down the process of crystal growth and recrystallization of the amorphous phase into more stable crystalline forms, which leads to a change in the morphology and structure of a carbonate precipitate. It has also been shown that polycarboxylic acids increase the colloidal stability of a mixed dispersion of carbonates and kaolin. The synergism of the stabilizing effect of mixtures of different hydrophobicity-polyacids was noted: in the presence of a mixture of polyacrylic acid with a copolymer of methacrylic acid with turpentine terpene, the stabilization effect increases 2 times compared to dispersion without additives and 1.4–1.8 times compared with individual components of the mixture. С целью изучения влияния молекулярно-структурного строения карбоксилсодержащих полимеров на их ингибирующее и стабилизирующее действие в процессах осадкообразования был исследован ряд полимерных кислот с различным содержанием карбоксильных групп (Х): полиакриловая кислота (Мn = 5100 г-моль–1, Х = 61,11 %), полиметакриловая кислота (Мn = 5500 г-моль–1, Х = 48,79 %), сополимер метакриловой кислоты с терпеном скипидара (α-пинен) (Мn = 3500 г-моль–1, Х = 14,54 %). Установлено, что введение поликислот замедляет процесс роста кристаллов и приводит к изменению морфологии и структуры осадка карбонатов в результате рекристаллизации аморфной фазы в более устойчивые кристаллические формы. Показано, что поликарбоновые кислоты повышают коллоидную стабильность смешанной дисперсии карбонатов и каолина. Отмечен синергизм стабилизирующего действия смесей поликислот с различной гидрофобностью: в присутствии смеси полиакриловой кислоты с сополимером метакриловой кислоты с терпеном скипидара стабилизационный эффект возрастает 2 раза по сравнению с дисперсией без добавок и в 1,4–1,8 раза по сравнению с индивидуальными компонентами смеси.

Production of drinking water using a multi-barrier approach integrating nanofiltration: a pilot scale study

A multi-barrier system was studied for the production of drinking water with high chemical and microbiological quality. The integration of nanofiltration (NF) and ultraviolet (UV) photolysis was tested at pilot scale in a surface water treatment plant. The NF membranes tested, Desal DK and NF270, allow for the production of permeates with high quality standards, although the membrane with higher molecular weight cut-off (NF270) revealed to be the best option for surface water treatment due to its higher permeability. The NF270 membrane was also efficient to deliver high quality water, even under high pollutant concentrations, making possible to operate with water recovery rates as high as 98%. Extensive studies were performed in the water treatment plant where the proposed system was tested at three locations of the drinking water production line. Seeking to achieve the best compromise between high recovery rate, high retention of chemicals and microorganisms as well as preventing operational problems (flux decline and fouling), it was found that the integrated system should be placed after the conventional sand filtration, operating at a 91% recovery rate. Under the selected conditions – TMP of 8 bar and recovery rate of 91% – it is possible to operate at constant permeability without flux decline for a period of 15 days, after which a gentle CIP procedure is recommended. Membrane fouling was also investigated and the major foulant classes identified were proteins, polysaccharides and humic acids. A cleaning protocol was also tested and the impact of each cleaning step on the recovery of permeability evaluated

Получение сополимеров терпенов с метакриловой кислотой и их влияние на устойчивость неорганических дисперсий в присутствии катионных поверхностно-активных веществ

Copolymers of methacrylic acid and natural terpene monomers (α-pinene; β-pinene; ∆3-karene) with the molecular weight of (0.3–0.5)∙104 and a content of carboxyl groups of 14.5–16.3 % were synthesized. For the synthesized copolymers, hydrodynamic radius and the Kuhn segment, which characterizes flexibility of a polymer chain, were determined, as well as the Huggins constant in aqueous and saline solutions, and concentration regions for formation of supramolecular structures. In the presence of a cationic surfactant (benzetonium chloride, Hyamine), depending on the concentration of copolymers in the system, polymer-surfactant complexes were formed in soluble and insoluble forms. It has been shown that the effectiveness of the stabilizing action of soluble complexes with respect to an aqueous dispersion of calcium carbonate increases with an increase in the content of nonpolar groups in the polymer chain. A cationic surfactant (Hyamine) has been proposed as a precipitant in the method for the quantitative determination of carboxyl-containing polymers in aqueous and saline media. Синтезированы сополимеры на основе метакриловой кислоты и природных терпеновых мономеров (α-пинен, β-пинен, ∆3-карен) с молекулярной массой (0,3–0,5)∙104 и содержанием карбоксильных групп 14,5–16,3 %. Для синтезированных сополимеров определены гидродинамический радиус и сегмент Куна, характеризующий гибкость полимерной цепи, константа Хаггинса в водном и солевом растворах, концентрационные области формирования надмолекулярных структур. В присутствии катионного ПАВ (бензетония хлорид, Hyamine) в зависимости от концентрации сополимеров в системе образуются комплексы «полимер–ПАВ» в растворимой и нерастворимой формах. Показано, что эффективность стабилизирующего действия растворимых комплексов в отношении водной дисперсии карбоната кальция возрастает с увеличением содержания неполярных групп в полимерной цепи. Катионный ПАВ (Hyamine) предложен в качестве осадителя в методе количественного определения карбоксилсодержащих полимеров в водной и солевой средах.