Iskanje po katalogu digitalne knjižnice

Opis: Bio-based membranes are becoming highly-desired low-cost, environmentally friendly, and readily available supports for the separation and purification of biomacromolecules. In this work, weak cation-exchange and highly (> 95%) microporous (> 80 μm) cellulose-based membranes were prepared from different weight ratios of carboxymethyl cellulose (CMC) as anionic polymer and cellulose nanofibrils (CNFs) as a stabilizing and structural filler, by the freeze-casting process and citric-acid (CA) mediated in situ cross-linking (esterification). It was ascertained that mono-esterified/grafted CA also contributes to the total carboxylic groups (1.7–2.6 mmol/g), while the CMC-induced CNF orientation affected the membrane’s morphology and lysozyme (Lys) binding capacity. A static binding capacity (SBC) between 370 and 1080 mg/g, and equilibrium within 3.3 h for 1 g/mL Lys was thus achieved with increasing the total solid and CMC content by forming more isotropic microporous structures. The selected membranes were then packed in a chromatographic housing, analyzed for pressure drop, and evaluated for dynamic binding capacity (DBC), depending on the process performance (flow rates, Lys concentration). A DBC in the 165–417 mg/g range was determined at a throughput of 0.5 mL/min, and elution yield of 78–99% with > 95% recovery. The Lys adsorption and transfer were reduced by the increasing flow rate and membrane density due to compressibility issues, resulting in smaller and irregularly distributed pores and the unavailability of carboxylic groups. Although the DBC was still comparable with the commercial CIM® monoliths, the convection-based transport of molecules inside the membrane and the membrane stiffness needs to be improved in further research.
Ključne besede: cation-exchange membrane, cellulose nanofibrils, carboxymethyl cellulose, citric acid, lysozyme, static and dynamic binding capacity
Objavljeno v DKUM: 17.03.2025; Ogledov: 0; Prenosov: 7
Celotno besedilo (3,04 MB)
Gradivo ima več datotek! Več...

Opis: This thesis focuses on creating a framework for evaluating the influence of closed-loop on supply chain performance in the case of petrochemical industry in the Egyptian context, with a focus to test the influence of sustainability on the supply chain performance, to investigate the function of sustainability as a mediator between reverse logistics and supply chain performance, and evaluate the impact of closed-loop supply chains (environmental legislation, customer awareness and economic motivations) on sustainable development. The gathering of primary data helped the current study's goals get accomplished. Surveys are used to gather data to estimate how reverse logistics impacts the effectiveness of the supply chain. The employees of supply chain companies in Egypt received the surveys from the researcher. The study's findings indicate a strong link between sustainability and reverse logistics. Additionally, there is a marginally significant correlation between supply chain performance and sustainability. The outcomes also showed that the closed-loop supply chain has little influence on supply chain efficiency and sustainability. Furthermore, there is a marginally significant association between supply chain effectiveness and reverse logistics. The results also revealed that sustainability has a function in supply chain performance and reverse logistics.
Ključne besede: closed loop-supply chain, reverse logistics, supply chain performance, sustainability, logistics, capacity building
Objavljeno v DKUM: 16.10.2024; Ogledov: 0; Prenosov: 13
Celotno besedilo (2,45 MB)

Opis: ntroduction: Health systems worldwide have heterogenous capacities and financing characteristics. No clear empirical evidence is available on the possible outcomes of these characteristics for population wellbeing. Aim: The study aims to provide empirical insight into health policy alternatives to support the development of health system architecture to improve population wellbeing. Method and results: We developed an unsupervised neural network model to cluster countries and used the Human Development Index to derive a wellbeing model. The results show that no single health system architecture is associated with a higher level of population wellbeing. Strikingly, high levels of health expenditure and physical health capacity do not guarantee a high level of population wellbeing and different health systems correspond to a certain wellbeing level. Conclusions: Our analysis shows that alternative options exist for some health system characteristics. These can be considered by governments developing health policy priorities.
Ključne besede: population wellbeing, health system capacity, public health system, health policy, neural network
Objavljeno v DKUM: 19.07.2024; Ogledov: 186; Prenosov: 11
Celotno besedilo (3,01 MB)
Gradivo ima več datotek! Več...

Opis: The paper presents and solves the problems of modeling and designing the required EV charging service capacity for systems with a slow dynamic component. This includes possible bursts within a peak hour interval. A simulation tool with a newly implemented capacity planning method has been developed and implemented for these needs. The method can be used for different system simulations and simultaneously for systems with high, medium, and low service dynamics. The proposed method is based on a normal distribution, a primary mechanism that describes events within a daily interval (24 h) or a peak hour interval (rush hour). The goal of the presented approach, including the proposed method, is to increase the level and quality of the EV charging service system. The near-optimal solution with the presented method can be found manually by changing the service capacity parameter concerning the criterion function. Manual settings limit the number of rejected events, the time spent in the queue, and other service system performance parameters. In addition to manual search for near-optimal solutions, the method also provides automatic search by using the automation procedure of simulation runs and increasing/decreasing the service capacity parameter by a specifically calculated amount.
Ključne besede: service system, capacity planning, bursts, rush-hour, normal distribution, stochastic process
Objavljeno v DKUM: 24.08.2023; Ogledov: 583; Prenosov: 53
Celotno besedilo (5,63 MB)
Gradivo ima več datotek! Več...

Opis: Unsaturated soils are maintaining their importance for researchers and there is still much need to investigate the many engineering aspects of these soils. A new technique is proposed here to predict the variation of the bearing capacity of unsaturated soils with matric suction. The proposed method is an extension of conventional bearing-capacity theories and conceptually based on the logarithmic model of the shear strength of unsaturated soils, which only include one unknown, unsaturated parameter (the airentry value, AEV). The possibility of predicting the unsaturated bearing capacity of soils is shown by the saturated effective shear-strength parameters c' and Ø' and the AEV from the soil-water retention curve (SWRC). Considering the necessity of validating new methods with other researchers’ data, the proposed equation is tested using the published unsaturated experimental study by the author, in addition to some reported experimental studies on the shear strength for unsaturated soils and also a model footing loading on unsaturated sand under controlled suction conditions. The results of the study indicate that there is a good comparison between the “unsaturated bearing capacities” obtained via predicted and measured unsaturated strength parameters (ctotal , Ø) and also between the measured/ calculated bearing values of a model footing loading. Consequently, it is shown that, without needing complex unsaturated testing facilities, the proposed equation is capable of predicting the unsaturated bearing capacity for both fine-grained and sandy soils, requiring only one unsaturated parameter, which can be obtained from the SWRC or predicted using the basic soil-index properties.
Ključne besede: unsaturated soils, unsaturated bearing capacity, suction strength, foundation design
Objavljeno v DKUM: 18.06.2018; Ogledov: 1252; Prenosov: 78
Celotno besedilo (347,24 KB)
Gradivo ima več datotek! Več...