Characterisation of the binding of dihydro-alpha-lipoic acid to fibrinogen and the effects on fibrinogen oxidation and fibrin formation

A reduced form of the alpha-lipoic acid, dihydro-alpha-lipoic acid (DHLA) is a potent, naturally occurring antioxidant which can be consumed as food constituent or as supplement at doses up to 600 mg/day. DHLA has inhibitory effect on coagulation as it can reduce concentrations of some coagulation factors. In this study, a direct interaction between DHLA and fibrinogen, the main protein in coagulation, is described. Binding constant for DHLA/fibrinogen complex is of moderate strength (104) and interaction probably occurs in D regions of fibrinogen, as shown by docking simulations. Fibrinogen stability remains the same with only marginal structural changes in its secondary structure favouring more ordered molecular organisation upon DHLA binding. Fibrinogen with bound DHLA forms fibrin with thicker fibers, as measured by coagulation assay and is protected from oxidation to certain extent. Obtained results support beneficial effects of DHLA on fibrinogen and consequently on coagulation process, suggesting that DHLA supplementation may be indicated for persons with an increased risk of developing thrombotic complications, particularly those whose fibrin is characterised by increased oxidative modification and formation of thinner and less porous fibers. Also, DHLA in complex with fibrinogen can be located at site of injury where it may exert antioxidant effects.This is the peer-reviewed version of the article: International Journal of Biological Macromolecules, 2020, 147, 319-325, doi: [https://dx.doi.org/10.1016/j.ijbiomac.2020.01.098]The published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3378

Treatment of construction waste in Serbia and the life cycle of buildings

One of the most important areas towards which the European building sector turns is the waste management strategy. Based on the principles of sustainable development, this strategy is instrumentalized through 3R concept in order to establish control over the progressive exhaustion of resources and reduce the burden of waste materials in the environment through a simultaneous application of three principles: reduce, reuse and recycle. Modern tendencies of management of construction waste are based on assessment and evaluation of the life cycle of buildings, aimed at review the possibility of introducing new concepts of design and construction of buildings, based on the principles of reuse and recycling. In this sense, the environmental characteristics of building materials and identification of their impact on the environment during the life cycle, become of great importance and one of the main instruments in the field of waste management. Enforcement of the 3R principles and waste management implementation mechanisms are introduced into the legal system of the European Union, whose rapid adoption and compliance with local legislation is expected by all member states and the countries of claimants for a place in the Union. On the way to regulate this area, Serbia has done a more complex part of work related to the formation of the local legislative framework for waste management and its harmonization with the basic principles of the EU. Simultaneously, in the previous period the first steps in technical realization of set goals were made. On the other hand, on the way to the final regulation of this area, Serbia expects additional efforts and involvement of all stakeholders in the promotion of basic principles of waste management, and the introduction of appropriate incentives, after the model of developed communities. This would determine further development of the construction sector, and put the problem of waste materials finally under control

Physicochemical characterisation of dihydro-alpha-lipoic acid interaction with human serum albumin by multi-spectroscopic and molecular modelling approaches

The binding of a popular food supplement and well-known antioxidant, dihydro-alpha-lipoic acid (DHLA) to human serum albumin (HSA) was characterised. The binding was monitored by several spectroscopic methods together with the molecular docking approach. HSA was able to bind DHLA with moderate affinity, 1.00±0.05×104 M-1. Spectroscopic data demonstrated that the preferential binding site for DHLA on HSA is IIA (Sudlow I). Both experimental and molecular docking analysis identified electrostatic (salt bridges) and hydrogen bonds as the key interactions involved in DHLA binding to HSA. Molecular docking confirmed that the Sudlow I site could accommodate DHLA and that the ligand is bound to the protein in a specific conformation. The molecular dynamic simulation showed that the formed complex is stable. Binding of DHLA does not affect the structure of the protein, but it thermally stabilises HSA. Bound DHLA had no effect on the susceptibility of HSA to trypsin digestion. Since DHLA is a commonly used food supplement, knowledge of its pharmacokinetics and pharmacodynamic properties in an organism is very important. This study further expands it by providing a detailed analysis of its interaction with HSA, the primary drug transporter in the circulation

Dihydro-alpha-lipoic acid binds and protects fibrinogen from oxidation and affects fibrin formation

A reduced form of the alpha-lipoic acid, dihydro-alpha-lipoic acid (DHLA) is a potent, naturally occurring antioxidant that is found in higher amounts in plants like spinach, broccoli, potatoes, tomatoes, carrots, beets and rice. DHLA can be consumed as a food supplement as well, at doses up to 600 mg/day. DHLA has an inhibitory effect on coagulation as it can reduce concentrations of some coagulation factors. This study investigated a direct interaction between DHLA and fibrinogen, the main protein in coagulation and hemostasis. DHLA binds fibrinogen with a moderate straight. Calculated constant from spectrofluorimetric titration for DHLA/fibrinogen complex was 104 M -1. Fibrinogen stability remains the same with only marginal structural changes in its secondary structure favouring more ordered molecular organisation upon DHLA binding, as determined by Fourier transform infrared spectroscopy. Coagulation assay showed that fibrinogen with bound DHLA forms fibrin with thicker fibres, as measured by coagulation assay and is protected from oxidation to a certain extent. Docking analysis showed that DHLA may bind fibrinogen in its D regions, which are directly involved in the fibrin formation. Obtained results support beneficial effects of DHLA on fibrinogen and consequently on coagulation process, suggesting that DHLA supplementation may be indicated for persons with an increased risk of developing thrombotic complications, particularly those whose fibrin is characterised by increased oxidative modification and formation of thinner and less porous fibres. Although further investigation is needed, our results suggest that DHLA in complex with fibrinogen can be located at the site of injury where it may exert antioxidant effects.45th FEBS Congress, Molecules of Life: Towards New Horizons, Ljubljana, Slovenia, July 3-8, 202

Properties of aluminum-steel plates explosively welded using Amonex explosive

Besides their application in munitions and armaments, explosives have a significant role in industrial applications, such as cladding or welding of metal plates. In the process of explosion welding, the energy of explosive detonation is used to achieve a metallurgical bond between two metal components, which are metallurgically compatible, but also those that are non-weldable by conventional methods. For this purpose, most often explosives of low values of detonation velocity are used, in order to avoid severe damage to the processed metal plates. The aim of this study was to investigate the possibility to use the industrial explosive Amonex, which belongs to a group of low-to-middle detonation velocity explosives, for welding of metallic materials. It consists of ammonium nitrate and TNT as energetic components and other inert ingredients and has a powdery consistency, easily applicable in a desirable layer over the metal plates to be welded. Within this research, Amonex was applied to weld plates of aluminium Al 2024 and steel Č0345. Besides the initial data on the used metal plates, the main properties of the used explosives are also given, since based on these properties the needed quantity of explosive was estimated. The procedure of welding was carried out in the configuration of parallel plates, and afterward the welded joint was examined. Ultrasonic method and chemical penetrants were used as non-destructive techniques, and then the samples were cut from the welded plate using water-jet, in order to perform microscopic analyses on the cross-section and to determine the indentation hardness in the area of the joint. It was observed that a good-quality welded joint was obtained, and that the selected explosive may find further application in this area

Могућност примене експлозива amonex у заваривању разнородних челичних плоча и утицај количине експлозива на квалитет завареног споја

Детонацијом експлозивних материја ослобађа се велика количина енергије у врло кратком времену, која се примењује за различите врсте корисног рада, како у привредне, тако и у војне сврхе. Поред приме- не експлозивних материја у убојним средствима и за рушење у рударству и грађевинарству, енергија детонације нашла је примену и у заваривању и об- ради метала. Применом енергије настале детонационим разлагањем експло- зива могуће је извршити заваривање метала, обликовање, резање, утицати на повећање његове чврстоће итд. Технологија заваривања експлозивом почела се развијати половином 20. века, и данас је заступљена за израду делова ва- здухоплова, наоружања и војне опреме, оклопних плоча са повећаном бали- стичком заштитом, специјалних цистерни, топлотних измењивача, посуда под притиском,специјалних индустријских резних алата и свих других производа који се не могу израдити неким другим конвенционалним поступком обраде металних материјала. Такође, значајна предност ове технологије је могућност израде вишеслојних материјала великих површина. Заваривање метала експлозијом остварује се као последица веома брзог судара метала под дејством продуката детонације, уз појаву високог притиска и пластичних деформација у облику таласа на граници споја и адијабатског локалног загревања површинских слојева металних материјала. У оквиру овог рада анализирана је могућност примене привредног екс- плозива Amonex у заваривању плоча од опружног челика 51CrV4 и конструк- ционог челика S355 J2. За изабрани експлозив Amonex, који је произведен у Корпорацији ТРАЈАЛ, претходно су измерене насипна густина и брзина дето- нације, где је коришћена метода мерења времена између две тачке у експлозив- ном пуњењу коришћењем електронског бројача са оптичким давачима. Током свих реализованих експеримената коришћена је иста поставка плоча. Коришћене су плоче димензија 150×200 mm. Горња плоча од опружног челика ознаке 51CrV4 дебљине 3 mm, која је убрзавана енергијом експлозије, била је постављена паралелно са непомичном доњом плочом израђеном од кон- струкционог челика ознаке S355 J2 дебљине 10 mm. Почетно одстојање између плоча износило је 4 mm, где су коришћена по 4 ивично постављена одстој- ника израђена од пластичне масе поли(метил метакрилат), скраћено PMMA. Коришћена су експлозивна пуњења три различите масе експлозива Amonex, који је у одговарајућем слоју био равномерно слободно насут на горњу плочу. Таквим експериментима омогућено је одређивање зависности квалитета зава- реног споја од масе примењеног експлозива. За одређивање квалитета завареног споја примењене су две технике ис- питивања без разарања: метода са течним пенетрантима MR68C и испитивање ултразвучним дефектоскопом ознаке Phasor XS. Потом су плоче исечене за даљу анализу, где су извршени микроскопски преглед пресека заварених споје- ва помоћу оптичког микроскопа типа Leitz Metalloplan, опремљеног камером DFC 295 и софтвером за обраду слике LAS 4.3.1. Ударна жилавост споја из- међу експлозијом заварених плоча испитана је на одговарајуће припремљеним епруветама помоћу Шарпијевог клатна ознаке Schenck trebel. Резултати испитивања показали су да експлозив Amonex може наћи примену у експлозивном заваривању, a најбољи резултати постигнути су код узорка завареног средњом количином експлозива. Код овог узорка добијене су највише вредности ударне жилавости на Шарпијевом клатну, док је код трећег завареног споја дошло до наглог пада ударне жилавости услед формирања међуслоја, растопљене фазе на споју, што је потврђено микроскопском ана- лизом. Ултразвучна дефектоскопија је показала да средњи узорак има највећу површину завареног споја, а узорак са најмање експлозива најмању површину завареног споја.Detonation of explosive substances releases a large amount of energy in a very short time, which is used for various types of useful work, both for economic and military purposes. In addition to the use of explosive substances in ordnance and for demolition in mining and construction, detonation energy has found its application in welding and metal processing. By applying the energy generated by the detonation of explosives, it is possible to weld metal, shape it, cut it, increase its solidity, etc. Explosion welding technology began to develop in the middle of the 20th century, and today it is used for the production of aircraft parts, weaponsand military equipment, armour plates with increased ballistic protection, special tanks, heat exchangers, pressure vessels, special industrial cutting tools and all other products which cannot be produced by any other conventional method of processing metal materials. Also, a significant advantage of this technology is the possibility of manufacturing multi-layer materials of large surfaces. The explosion welding of metals is done as a result of the very fast collision of metals under the effect of detonation products, with the appearance of high pressure and plastic deformations in the form of waves at the fusion line and adiabatic local heating of the surface layers of metal materials. In this paper, the possibility of using commercial explosive Amonex for the welding of plates made of 51CrV4 spring steel and S355 J2 structural steel was analysed. For the selected explosive Amonex, which was produced by TRAJAL Corporation, the bulk density and detonation velocity were previously measured, whereby the method of measuring the time between two points in the explosive charge using an electronic counter with optical sensors was used. During all conducted experiments, the same arrangement of plates was used. Plates of dimension 150×200 mm were used. The upper plate of 3 mm thick 51CrV4 spring steel, which was accelerated by the energy of the explosion, was placed parallel to a stationary lower plate made of 10 mm thick S355 J2 structural steel. The initial distance between the plates was 4 mm, where 4 edge spacers made of plastic mass poly(methyl methacrylate), abbreviated PMMA, were used. Explosive charges of three different masses of Amonex explosive were used, which was evenly and freely poured in the appropriate layer on the upper plate. Such experiments made it possible to determine the dependence of the quality of the welded joint on the mass of the explosive used. To determine the quality of the welded joint, two non-destructive testing techniques were applied: the method with liquid penetrants MR68C and testing with an ultrasonic defectoscope Phasor XS. Then the plates were cut for further analysis, whereby the microscopic examination of the sections of the welded joints was performed using the Leitz Metalloplan optical microscope equipped with a DFC 295 camera and LAS 4.3.1 image processing software. The impact toughness of the joint between the explosion-welded plates was tested on appropriately prepared test tubes using the Charpy pendulum Schenck trebel. The test results showed that Amonex explosive can be used in explosion welding, and the best results were achieved with a sample welded with a medium amount of explosive. In this sample, the highest values of impact toughness were obtained on the Charpy pendulum, while in the third welded joint there was a sudden decrease in impact toughness due to the formation of an intermediate layer, a molten phase at the joint, which was confirmed by microscopic analysis. Ultrasonic defectoscopy showed that the middle sample had the largest area of the welded joint, and the sample with the least explosive had the smallest area of the welded joint

Osobine eksplozivno zavarenih ploča aluminijuma i čelika upotrebom Amonex eksploziva

The aim of this study was to investigate the possibility to use the industrial explosive Amonex, which belongs to a group of low-to-middle detonation velocity explosives, for welding of metallic materials. It consists of ammonium nitrate and TNT as energetic components and other inert ingredients and has a powdery consistency, easily applicable in a desirable layer over the metal plates to be welded. Within this research, Amonex was applied to weld plates of aluminium Al 2024 and steel 1.0216 (according to EN 10027-2). The procedure of welding was carried out in the configuration of parallel plates, and afterwards the welded joint was examined. Ultrasonic method and infrared imaging were used as non-destructive techniques, and then the samples were cut from the welded plate using water-jet, in order to perform microscopic analyses of the cross-section in the joint area. It was observed that a good-quality welded joint was obtained, and that the selected explosive may find further application in this area. However, certain nonwelded area was observed, encouraging future modification of the welding procedure set-up.Cilj ove studije je ispitivanje mogućnosti upotrebe industrijskog eksploziva Amonex, koji pripada grupi eksploziva male-do-srednje brzine detonacije, za zavarivanje metalnih materijala. Ovaj eksploziv se sastoji od amonijum nitrata i TNT-a kao energetskih komponenti i drugih inertnih sastojaka, ima praškastu strukturu i lako se nanosi u željenom sloju preko metalnih ploča koje se zavaruju. U okviru ovog istraživanja, Amonex je primenjen na zavarenim pločama aluminijuma Al 2024 i čelika 1.0216 (oznake prema EN 10027-2). Postupak zavarivanja izveden je na paralelno postavljenim pločama, nakon čega je izvršen pregled zavarenog spoja. Kao metode IBR korišćene su ultrazvučna metoda i termovizijsko ispitivanje. Primenom vodenog mlaza iz zavarene ploče su isečeni uzorci u cilju ispitivanja mikrostrukture poprečnog preseka zavarenog spoja. Uočeno je da je dobijen kvalitetan zavareni spoj, te da odabrani eksploziv može naći dalju primenu u ovoj oblasti. Međutim, takođe su uočene i određene površine nezavarenog područja, što je nametnulo potrebu za izmenama postavke ovog postupka zavarivanja

Quality of explosively welded steel plates using demex explosive

Заваривање експлозивом се често користи када конвенционалне методе заваривања не могу да обезбеде заварени спој два различита материјала, али и када треба заварити неку специфичну геометрију или велике површине металних плоча. Остваривање споја код заваривања експлозивом се заснива на динамичком дејству великог притиска створеног екплозијом. У ту сврху најчешће се користе индустријски експлозиви ниских параметара детонације, а један од њих је DEMEX, произвођача TRAYAL, из Србије. У овом истраживању DEMEX је примењен за заваривање плоча две различите врсте челика. Пре експерименталног поступка заваривања одабраних металних плоча, експлозив добијен од произвођача је подвргнут улазној контроли квалитета: мерењу његове насипне густине и брзине детонације, коришћењем оптичких сонди и фотодетектора повезаног са електронским бројачем. Експериментална поставка за заваривање била је следећа: експлозив DEMEX у прашкастом стању нанесен је у равномерном слоју преко горње челичне плоче, која је хоризонтално постављена преко доње плоче од друге врсте челика, у паралелном положају, са малим дрвеним дистанцерима ивично постављеним између њих. Активација је извршена електродетонирајућом капислом и малим бустером од пластичног експлозива. Заварени спој је испитан применом метода ултразвучне дефектоскопије, течним пенетрантима и микроструктурне анализе завареног споја. Микроструктурне анализе попречног пресека заварених плоча урађене су на стерео и оптичом микроскопу како би се анализирала зона завареног споја.Explosion welding is often used when conventional welding methods cannot provide welded joint of two dissimilar materials, but also when some specific geometry should be welded, or large surfaces of metal plates. The formation of a joint in explosive welding is based on the dynamic effect of the high pressure created by the explosion. For this purpose, most often some industrial explosives of low detonation parameters are used, and one of them is DEMEX, produced by TRAYAL, Serbia. In this research DEMEX was applied to weld plates of two different types of steel. Prior to the experimental procedure of welding, the selected metal plates, the explosive obtained from the producer was subjected to initial quality control: measurement of its bulk density and detonation velocity, using optical probes and a photodetector connected with an electronic counter. The experimental setup for welding was as follows: explosive DEMEX in powdery state was applied in a uniform layer over the upper plate, which was horizontally placed over the lower plate, in parallel position, with small wooden spacers, marginally placed between them. Activation was performed by an electro-detonating cap and a small booster of plastic explosive. The welded joint was examined using methods of ultrasonic defectoscopy, liquid penetrants testing and microstructural analysis of the welded joint. Cross-sectional microstructural analyses of the welded plates were performed using a stereo and optical microscope to analyze the weld zone

Preparation of CaO/γ-Al2O3 catalyst for biodiesel fuels. The catalytic activity in relation to thermal treatment

A heterogeneous base catalyst (CaO/γ-Al2O3) for biodiesel production from sunflower oil was prepared by the impregnation method. The catalyst was characterized by means of MIP and XRD methods. The catalytic activity of the nitrate-derived CaO/γ-Al2O3 was determined in relation to the calcination temperature ranging from 425 to 500 °C. The reaction was carried out in a batch type of reactor equipped with a reflux condenser. The maximum yield of biodiesel of almost 95% was achieved with the catalyst calcined at 475 °C under the following reaction conditions: reaction temperature of 60 °C, methanol to oil molar ratio of 12/1, reaction time of 5 h