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Electrical characteristics of transformer oil (TO) have been studied during normal and thermal aging conditions. In this paper, breakdown voltage (BDV), partial discharge (PD), heat transfer results and the physical mechanisms considering the impact of varying the diameter of Al₂O₃ nanoparticles (NPs) have been investigated. Different quantities of the two sizes of Al₂O₃ were added to the oil using a two-step method to determine the positive effect of NPs on the electrical and thermal properties of TO. Finally, the physical mechanisms related to the obtained experimental results have been performed.

The implementation of nanoparticles in this paper was provided by US Research Nanomaterials, Inc., USA. The provided Al₂O₃ NPs have an average particle size of 20–80 nm and a specific surface area of 138 and 58 m²/g, respectively, which have a purity of over 99%. Thermal aging has been done. The IEC 60156 standard has been implemented to calculate the BDV, and a 500-mL volume test cell (Apar TO 1020) has been used. PD test is performed according to Standard IEC 60343, and a JDEVS-PDMA 300 device was used for this test.

BDV tests indicate that 20 nm Al₂O₃ is more effective at improving BDV than 80 nm Al₂O₃, with an improvement of 113% compared to 99% for the latter. The analysis of Weibull probability at BDV indicates that 20 nm Al₂O₃ performs better, with improvements of 141%, 125% and 112% at probabilities of 1, 10 and 50%, respectively. The results of the PD tests using the PDPR pattern also show that 20 nm Al₂O₃ is superior. For the heat transfer test, 0.05 g/L of both diameters were used to ensure fair conditions, and again, the advantage was with 20 nm Al₂O₃ (23% vs 18%).

The effect of Al₂O₃ NP diameter (20 and 80 nm) on various properties of virgin and aged TO has been investigated experimentally in this paper to examine the effect of proposed NP on electrical improvement of TO.

This study aims to examine the role of salespeople’s skills in relative and absolute SP in business-to-business (B2B) settings of services firms. This conceptual logic reported in meta-analytical works, that salespeople’s skills relate directly to their sales performance (SP), is questioned.

his research relies on existing theory and previous studies on SP drivers and SP measures. The literature identifies a set of common denominators on the role of salespeople’s skills regarding their SP, all of which are tested in this study. Based on a deductive approach and questionnaire survey, 732 service firms in Norway were targeted. A total of 389 questionnaires were returned, generating a response rate of 53.1%.

A total of 10 out of 12 hypothesized relationships in the research model dealing with the relationship between SP drivers and SP turn out to be non-significant. The hypothesized relationship in the research model between relative and absolute SP is also supported.

The results reported in this study, based on a large sample of service firms, empirically confirm that the direct effect is generally overestimated. Empirical evidence is provided that sheds additional light on the role of salespeople’s skills in relative and absolute SP in B2B settings of services firms.

This study offers meaningful and relevant insights into the monitoring of SP drivers to practitioners in B2B sales settings of services firms. Salespeople need to learn about gathering knowledge in training programs about each customer and their specific situation. Firms should strive to recruit salespeople who possess the appropriate skills, taking into consideration their customers and specific situations related to them, such as experiences from competitors. Salespeople may be organized around similar customers and similar customer situations, rather than geographical assignments.

Overall, this research contributes insights into the role played by salespeople’s skills in relative and absolute SP in B2B settings of services firms. In particular, the research contributes additional insights into the non-existent role of interpersonal presentation and communication skills, adaptiveness of sales approach and sales behavior skills and product/technology-related knowledge skills in salespeople’s relative and absolute SP in B2B settings of services firms.

This study examines the osteoconductive and healing capabilities of locally implanted synthetic hydroxyapatite (sHAp) derived from eggshells in the central incisor sockets of rats.

Toxicity experiments were conducted in vitro and in vivo, to testify the safety dosage of sHAp. Around 24 mature male Sprague–Dawley (SD) rats had their upper central incisors extracted. The rats were placed into three groups of eight rats each: Group 1: the sockets of extracted central incisors were left unfilled (control), Group 2: filled up with commercially available hydroxyapatite (HAp) and Group 3: implanted with sHAp locally retrieved from eggshells. After extraction, four rats from each group were sacrificed at 2nd and 4th weeks. Maxillary tissue sections were obtained and stained with hematoxylin and eosin (H&E) and Masson’s trichome (MT) staining. Anti-osteocalcin (OCN) and proliferating cell nuclear antigen (PCNA) were used primary antibodies for immunohistochemistry (IHC) special labeling.

The results showed that the locally implanted sHAp was non-toxic and safe in cell lines (human osteoblast and fibroblast) and animals. Histological analysis of H&E, MT and IHC showed that the sockets treated with locally implanted sHAp from eggshells were filled with new bone tissue of comparable thickness to other groups.

This unique technique uses locally implanted eggshell-derived sHAp with osteoconductive characteristics. In an in vivo model, sHAps increased OCN and PCNA expression to improve bone repair.