Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of t...Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of the present study was to determine the root canal length of teeth of Bantu patients extracts attending the Teaching Hospital of Kinshasa University. Methods and Material: Prospective cross-sectional study was carried out in the service of Conservative Dentistry. The patients suffering with pulpitis of permanent teeth which were selected for root canal treatment during the period of January 2014 to December 2016 were included. All patients whose main root canals were inaccessible, teeth carrying prosthesis, teeth with large coronal decay, teeth having periapical periodontitis, supernumerary teeth, wisdom and primary teeth were excluded. Results: The upper canines presented some significant longer canals compared to the lower canine (23.4 ± 2.3 mm and 21.6 ± 1.8 mm). Palatal canals of the first and second molar were respectively longer as compared to the superior teeth canals (21.5 ± 1 mm, 21.3 ± 2 mm). The distal canals of the first and second molar were the longest in the mandibular arch respectively measuring 20.7 ± 2.0 mm and 21.5 ± 1.7 mm. Conclusion: Data obtained from Bantu patients show slightly shorter roots compared to some European populations, but longer than some Asian populations.展开更多
Soil cores from a field growing barley and barley mutants without root hairs under conventional and minimum tillage were sampled. They were X-ray scanned to produce a 3D image and then the roots were washed out and we...Soil cores from a field growing barley and barley mutants without root hairs under conventional and minimum tillage were sampled. They were X-ray scanned to produce a 3D image and then the roots were washed out and weight and length were determined by conventional means. Root volume and surface area were then calculated from the 3D images using state of the art software and methodology, and the measured and calculated measures were correlated. The only strong and significant correlation was between measured weight and calculated volume for mutants without root hairs. It is concluded that the software cannot segment out very small roots, but segmentation accuracy also depends on root structure in some unknown way. Any study using X-ray computed tomography to quantify roots as they grow in situ should start with a calibration for the conditions in question.展开更多
When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ri...When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ring gear is in the preliminary stage, and the distribution rule of the prestressing and the influence of each parameter on the interference prestressing have not been derived. In this paper, based on the method of calculating the prestressing of the thick cylinder in interference fit, the ring gear is found to be equivalent to a thick cylinder, and the distribution rule of prestressing of the ring gear in the interference fit is inferred. Then, by modeling and analyzing the gearbox body and ring gear in the interference fit using ABAQUS, the distribution rule of prestressing the ring gear in the interference fit is obtained through a numerical simulation. Finally, the prestressing of the ring gear in the interference fit is measured using X-ray di raction, and the distribution rule of prestressing of the ring gear in the interference fit is obtained through analysis. Compared with the distribution rule of prestressing in theory, numerical simulation, and experiment, the theoretical distribution rule of prestressing is amended through a statistical method, and a more accurate formula of prestressing is obtained. Through the calculation of the stress and bending moment in the dangerous section of the ring gear through prestressing, the formula for checking the tooth root flexural fatigue strength in the interference fit prestressing is inferred. This research proposes a tooth root bending strength conditional formula for the inner ring gear of the interference fit, which serves as a guide for the design and production of the actual interference joint inner ring gear.展开更多
The aim of the study was to assess the effects of various biopreparations on the growth of the strawberry root system, the number of spores of mycorrhizal fungi, the total number of bacteria in the rhizosphere soil, a...The aim of the study was to assess the effects of various biopreparations on the growth of the strawberry root system, the number of spores of mycorrhizal fungi, the total number of bacteria in the rhizosphere soil, and the degree of mycorrhizal association in the roots of two strawberry cultivars. The experiment with strawberry plants was established in the spring of 2010 in the Experimental Orchard of the Institute of Horticulture in Dabrowice. The objects of research were “frigo” strawberry plants of the cultivars Elsanta and Elkat. The following experimental combinations were used: control, control NPK (standard NPK fertilization), manure, mycorrhizal preparation Micosat F, Humus UP, Humus Active + Aktywit PM, BioFeed Amin, BioFeed Quality, Tytanit, Vinassa, Florovit Eko, and Florovit Pro Natura. The use of the biopreparation BioFeed Quality resulted in a six-fold increase in root length and a seven-fold increase in root surface area. Compared with NPK fertilization, application of the preparation BioFeed Amin contributed to an eight-fold increase in root volume, and the use of Vinassa increased 24-fold the number of root tips of Elkat strawberry plants. Micosat F and Humus UP caused a five-fold increase in mycorrhizal frequency in the roots of strawberry plants. Micosat F and manure contributed to a two- and four-fold increase, respectively, in the number of spores in the rhizosphere soil. Application of the preparations Humus UP, BioFeed Amin and Florovit Eko doubled the total number of bacteria and filamentous fungi in the rhizosphere soil of strawberry plants of the cultivars Elsanta and Elkat in comparison with NPK fertilization. Fertilization with the biopreparations intensified the growth of the root system and increased the number of spores of AM fungi, mycorrhizal frequency, and the total number of bacteria and filamentous fungi in the soil.展开更多
文摘Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of the present study was to determine the root canal length of teeth of Bantu patients extracts attending the Teaching Hospital of Kinshasa University. Methods and Material: Prospective cross-sectional study was carried out in the service of Conservative Dentistry. The patients suffering with pulpitis of permanent teeth which were selected for root canal treatment during the period of January 2014 to December 2016 were included. All patients whose main root canals were inaccessible, teeth carrying prosthesis, teeth with large coronal decay, teeth having periapical periodontitis, supernumerary teeth, wisdom and primary teeth were excluded. Results: The upper canines presented some significant longer canals compared to the lower canine (23.4 ± 2.3 mm and 21.6 ± 1.8 mm). Palatal canals of the first and second molar were respectively longer as compared to the superior teeth canals (21.5 ± 1 mm, 21.3 ± 2 mm). The distal canals of the first and second molar were the longest in the mandibular arch respectively measuring 20.7 ± 2.0 mm and 21.5 ± 1.7 mm. Conclusion: Data obtained from Bantu patients show slightly shorter roots compared to some European populations, but longer than some Asian populations.
文摘Soil cores from a field growing barley and barley mutants without root hairs under conventional and minimum tillage were sampled. They were X-ray scanned to produce a 3D image and then the roots were washed out and weight and length were determined by conventional means. Root volume and surface area were then calculated from the 3D images using state of the art software and methodology, and the measured and calculated measures were correlated. The only strong and significant correlation was between measured weight and calculated volume for mutants without root hairs. It is concluded that the software cannot segment out very small roots, but segmentation accuracy also depends on root structure in some unknown way. Any study using X-ray computed tomography to quantify roots as they grow in situ should start with a calibration for the conditions in question.
基金Supported by Hunan Provincial Natural Science Foundation of China(Grant No.2018JJ4006)National Independent Innovation Demonstration Area Foundation of Changsha Zhuzhou Xiangtan(Grant No.2018XK2302)
文摘When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ring gear is in the preliminary stage, and the distribution rule of the prestressing and the influence of each parameter on the interference prestressing have not been derived. In this paper, based on the method of calculating the prestressing of the thick cylinder in interference fit, the ring gear is found to be equivalent to a thick cylinder, and the distribution rule of prestressing of the ring gear in the interference fit is inferred. Then, by modeling and analyzing the gearbox body and ring gear in the interference fit using ABAQUS, the distribution rule of prestressing the ring gear in the interference fit is obtained through a numerical simulation. Finally, the prestressing of the ring gear in the interference fit is measured using X-ray di raction, and the distribution rule of prestressing of the ring gear in the interference fit is obtained through analysis. Compared with the distribution rule of prestressing in theory, numerical simulation, and experiment, the theoretical distribution rule of prestressing is amended through a statistical method, and a more accurate formula of prestressing is obtained. Through the calculation of the stress and bending moment in the dangerous section of the ring gear through prestressing, the formula for checking the tooth root flexural fatigue strength in the interference fit prestressing is inferred. This research proposes a tooth root bending strength conditional formula for the inner ring gear of the interference fit, which serves as a guide for the design and production of the actual interference joint inner ring gear.
文摘The aim of the study was to assess the effects of various biopreparations on the growth of the strawberry root system, the number of spores of mycorrhizal fungi, the total number of bacteria in the rhizosphere soil, and the degree of mycorrhizal association in the roots of two strawberry cultivars. The experiment with strawberry plants was established in the spring of 2010 in the Experimental Orchard of the Institute of Horticulture in Dabrowice. The objects of research were “frigo” strawberry plants of the cultivars Elsanta and Elkat. The following experimental combinations were used: control, control NPK (standard NPK fertilization), manure, mycorrhizal preparation Micosat F, Humus UP, Humus Active + Aktywit PM, BioFeed Amin, BioFeed Quality, Tytanit, Vinassa, Florovit Eko, and Florovit Pro Natura. The use of the biopreparation BioFeed Quality resulted in a six-fold increase in root length and a seven-fold increase in root surface area. Compared with NPK fertilization, application of the preparation BioFeed Amin contributed to an eight-fold increase in root volume, and the use of Vinassa increased 24-fold the number of root tips of Elkat strawberry plants. Micosat F and Humus UP caused a five-fold increase in mycorrhizal frequency in the roots of strawberry plants. Micosat F and manure contributed to a two- and four-fold increase, respectively, in the number of spores in the rhizosphere soil. Application of the preparations Humus UP, BioFeed Amin and Florovit Eko doubled the total number of bacteria and filamentous fungi in the rhizosphere soil of strawberry plants of the cultivars Elsanta and Elkat in comparison with NPK fertilization. Fertilization with the biopreparations intensified the growth of the root system and increased the number of spores of AM fungi, mycorrhizal frequency, and the total number of bacteria and filamentous fungi in the soil.
