Assessing MWCNT-graphene surface energy through in situ SEM peeling

Carbon nanotubes (CNTs) are envisioned as ideal filaments for next-generation nanocomposites due to their high strength-to-weight ratios. However, while individual nanotubes are strong, interfaces between tubes cannot bear significant load due to the weak van der Waals forces that govern their behavior. Premature interfacial failure could thus counteract the inherent strength of carbon nanotubes and, in turn, prevent CNT-based composites from achieving optimal mechanical performance. To increase the load bearing capacity of these interfaces, interlayer crosslinking schemes have been proposed using chemical functionalization. For instance, introduction of hydrogen bonds or additional van der Waals bonds between tubes could improve load transfer between CNTs. While introducing chemical groups on CNT surfaces may enhance intermolecular interactions at these interfaces, a means of quantitatively evaluating changes in interlayer adhesion as a result of to these treatments needs to be defined. In addition, as sizes of CNTs will inherently vary within a composite, it is important that such energy measurements be normalized irrespective of tube dimensions. Here we report an experimental peeling technique that can be used to measure the adhesion energy between multiwalled carbon nanotubes (MWCNTs) and graphene. Peeling tests conducted in situ a scanning electron microscope allow direct visualization of the nanoscale peeling process which, in turn, enables adhesion energy to be estimated through classical fracture analysis. The applicability of this analysis is validated by finite element simulations with boundary conditions derived from experiments. The effective contact width between tubes and graphene is estimated via atomistic simulations, providing a means to normalize interaction energy per unit area. The surface energies of bare MWCNT-graphene interfaces found in this study compare favorably with theoretical and experimental values reported for graphite. This method can serve as a foundation for evaluating the enhancements afforded by chemical functionalization, which is a critical step toward the development of strong, lightweight composites that effectively utilize the full mechanical potential of CNTs

Screening of suitable cationic dopants for solar absorber material CZTS/Se: A first principles study

The earth abundant and non-toxic solar absorber material kesterite Cu2ZnSn(S/Se)(4) has been studied to achieve high power conversion efficiency beyond various limitations, such as secondary phases, antisite defects, band gap adjustment and microstructure. To alleviate these hurdles, we employed screening based approach to find suitable cationic dopant that can promote the current density and the theoretical maximum upper limit of the energy conversion efficiency (P(%)) of CZTS/Se solar devices. For this task, the hybrid functional (Heyd, Scuseria and Ernzerhof, HSE06) were used to study the electronic and optical properties of cation (Al, Sb, Ga, Ba) doped CZTS/Se. Our in-depth investigation reveals that the Sb atom is suitable dopant of CZTS/CZTSe and also it has comparable bulk modulus as of pure material. The optical absorption coefficient of Sb doped CZTS/Se is considerably larger than the pure materials because of easy formation of visible range exciton due to the presence of defect state below the Fermi level, which leads to an increase in the current density and P(%). Our results demonstrate that the lower formation energy, preferable energy gap and excellent optical absorption of the Sb doped CZTS/Se make it potential component for relatively high efficient solar cells

Managing Thyroid Microcarcinomas

Papillary thyroid microcarcinomas (PTMCs) are the most common form of classic papillary thyroid carcinoma (PTC). PTMCs are typically discovered by fine-needle-aspiration biopsy (FNAB), usually with sensitive imaging studies, or are found during thyroid surgery in a patient without a previously known history of thyroid carcinoma. However, the definition of PTMC has not always been universally accepted, thus creating controversy concerning the diagnosis and treatment of PTMC. The aim of this review is to summarize the clinical features of PTMC and identify the widely differing opinions concerning the diagnosis and management of these small ubiquitous thyroid tumors

Thermodynamics of 5-bromouracil tautomerisation from first-principles molecular dynamics simulations

The authors acknowledge support from the Engineering and Physical Sciences Research Council (EPSRC) UK National Service for Computational Chemistry Software (NSCCS); from GENCI (Grand équipement national de calcul intensif); and from CINES (Centre informatique national de l’enseignement supérieur). LFH and TvM gratefully acknowledge support from the HPC-EUROPA2 project with the support of the European Commission - Capacities Area - Research Infrastructures. LFH is grateful to the EPSRC for studentship support through the Doctoral Training Account scheme (grant code EP/K503162/1).We modelled the driving force for aqueous keto-to-enol tautomerisation of 5-bromouracil, a mutagenic thymine analogue, by first-principles molecular dynamics simulations with thermodynamic integration. Using interatomic distance constraints to model the water-assisted (de)protonation of 5-bromouracil in a periodic water box, we show that the free energy for its enolisation is lower than that of the parent compound, uracil, by around 3.0 kcal/mol (BLYP-D2 level), enough to significantly alter the relative tautomeric ratios. Assuming the energetic difference also holds in the cell, this finding is evidence for the “rare tautomer” hypothesis of 5-bromouracil mutagenicity (and, possibly, that of other base analogues).Postprin

REENGINEERING HVAC EQUIPMENT DISTRIBUTION NETWORK IN EASTERN EUROPE

Šis darbs satur pētījumus par uzņēmuma AVK izplatīšanas tīkla pārveidi un izplatītāja darbības novērtējumu, balstoties uz izstrādāto praktisko metožu rezultātiem. Darbs sastāv no vairākām daļām. Teorētiskajā daļā apskatītas nozīmīgākās definīcijas un koncepcijas, kas pielie-totas šajā pētījumā. Nākamā sadaļa izksaidro veicamā pētījuma metodoloģiju. Trešā daļa ir pats empīriskais pētījums; kas sniedz informāciju par pētāmā uzņēmuma uzbūvi, struktūru un pastāvošo izplatīšanas tīklu. Nodaļa beidzas ar pielietotā tirgus pārskata veida analīzi un novērtējumu, attēlo izplatītāja novērtējuma procesu. Maģistra darba nobeigumā tiek piedāvāta izplatīšanas tīkla pārveides stratēģija un secinājumi, kas apkopo pētījuma rezultātus. Atslēgas vārdi: mārketinga kanāli, izplatīšanas tīkli, AVK, novērtējumsThis paper represents a study of distribution network reengineering and distributor per-formance assessment of the HVAC company with implication on elaboration of practical me-thods of evaluation. The paper consists of several parts. In the theoretical part of the paper im-portant definitions and concepts that are relevant to current research are presented. The second part provides information on methodology of the conducted research. The third part is an empiri-cal study, it provides information on researched organization, its structure and existing distribu-tion network. The chapter ends with analysis and evaluation of applicable market coverage mode and describes the process of distributor assessment. The paper ends with proposed distribution network reengineering strategy and conclusion that summarizes results of the research. Keywords: Marketing Channels, Distribution Network, HVAC, Assessmen

The role of state finance audit in the system of accounting and analytical support of the state funds management system

During the period of martial law, the problem of the need for constant control over state finances in connection with their limitations and the importance of effective use became important. The issues of the activities of audit firms and the effective organization of audits are constantly in the focus of attention of scholars. The purpose of the article was to substantiate the theoretical aspects and provide scientific and practical recommendations aimed at improving the audit of state finances. The method of induction was used at the stage of collecting, systematizing and processing information for conducting research, deduction – in the process of theoretical understanding of the main questions and problems of the audit of state finances and the search for the root causes of their occurrence, generalization – during the identification of the main features and properties of the system of accounting and analytical support of the audit of state finances, methods of comparison, analysis, synthesis, abstract-logical method. Scientific works were summarized and analysed in order to determine the essence of important components of scientific research, in particular: audit of state finances, state financial audit, accounting and analytical information, accounting and analytical support and the main components of an effective system of management and control over state finances were determined. The main components of financial control in the public sector of Ukraine are schematically presented, and the place of public finance audit as a component of state financial control is determined. The need to distinguish the concepts of “audit of state finances” and “state financial audit” was discussed. The main conditions that contribute to the creation of an effective system of management and control over state funds are highlighted. Common and distinctive features of control over state funds in Ukraine and foreign countries are identified. The main problems and shortcomings of the system of management of state funds are identified and recommendations for their solution are provided. The results of the study can be used by all state enterprises that are looking for new approaches in management and strive for the effective distribution of state funds in the conditions of martial la