In this study,the fibers of invasive species Agave americana L.and Ricinus communis L.were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers.Cell...In this study,the fibers of invasive species Agave americana L.and Ricinus communis L.were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers.Cellulose nanofibers were obtained by two methods,based on either alkaline or acid hydrolysis.The morphology,chemical composition,and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM)together with energy-dispersive X-ray spectroscopy(EDX),dynamic light scattering(DLS),X-ray diffraction(XRD),and Fourier transform infrared(FTIR)spectroscopy.The crystallinity indexes(CIs)of the cellulose nanofibers extracted from A.americana and R.communis were very high(94.1%and 92.7%,respectively).Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T)cells were also performed.The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e.,0-500μg/mL).Our results showed that the nanocellulose extracted from A.americana and R.communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.展开更多
In this study, the principal objective is to compare the performances of an air<span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">cooled one cylinder, f...In this study, the principal objective is to compare the performances of an air<span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">cooled one cylinder, four</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">stroke direct injection diesel engine using the blends (5% by volume B5, 10% by volume B10) of diesel and biodiesels derived respectively from palm oil, castor oil and raphia sese De Wild oil with pure diesel. All the biodiesels used in this work come from the plant species of the democratic republic of Congo as listed above. The engine performances (power, torque and brake specific consumption)</span><span> </span><span style="font-family:Verdana;">at different engine speeds were determined at both full and partial loads. According to experimental results, the increments in the power output and torque when the mixtures of diesel and biodiesels were used</span><span style="font-family:Verdana;"> and</span><span> </span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> observed. </span><span style="font-family:Verdana;">On</span><span style="font-family:Verdana;"> the other side, the specific fuel consumption of the mixtures is higher than that of pure diesel</span><span> </span><span style="font-family:Verdana;">although the calculated lower heating values </span><span style="font-family:Verdana;">are almost within the same range</span><span style="font-family:Verdana;"> for the all studied fuels. Finally, in partial load 1/1, pure diesel blended with biodiesels B5 derived from castor oil presented high specific brake consumption values compared to the other fuels while B10 from the same oil presents low brake specific consumption values for power greater than 3</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">2 kW.</span>展开更多
Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The resu...Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The results showed that the insulation carried out by the L.C main office was a good quality (on thermal aspect), because the resistance of the insulation is so high (i.e. 3940 Mega Ohms under normal conditions). The results showed a lifespan of 50 years at a temperature of 40°C (close to ambient temperature), plus minus 33 years at a temperature of 70°C;plus minus 22 years at a temperature of 100°C and 12 years at a temperature of 160°C. Furthermore, information on chemical attack, the results showed that PVC cables have poor resistance to sulfuric acid attack (having a pH of 1.5 and a density of 1.84 g/cm<sup>3</sup>). LC/Gecamines is able to produce locally a good quality of electrical cables.展开更多
Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>...Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>3</sub>) to obtain manganese dioxide (MnO<sub>2</sub>). For precipitation tests, a pH ranging from 8 to 10, a time of one to two hours, and a temperature of 25°C and 50°C are the parameters that are considered. The calcination of MnCO<sub>3</sub> is carried out under the following conditions: time (1, 2, 3, and 4 hours) and temperature (370°C, 420°C, and 470°C). It should be noted that the temperature range selected for the calcination tests is based on thermodynamic data obtained using the HSC CHEMISTRY software. The results obtained show an effective recovery of manganese at 25°C, in one hour, with a pH of 8.5 with a precipitation yield and manganese content in the precipitate around 98.43% and 24.21%, respectively. During calcination tests, results show an increase in mass loss, for a constant calcination time, as temperature increases. On the other hand, increasing the calcination time at a given temperature causes an increase in mass loss. However, a significant decrease in mass loss is noted at 3 hours of calcination. The highest mass loss is obtained at a temperature of 470°C after 4 hours of calcination.展开更多
基金the Programa de Cooperación Territorial INTERREG V-A MAC 2014-2020 and Inv2Mac Project(MAC/4.6d/229)the partial support of FCT-Funda??o para a Ciência e a Tecnologia(Base Fund UIDB/00674/2020)+1 种基金ARDITI-Agência Regional para o Desenvolvimento da Investiga??o Tecnologia e Inova??o supported the study through the project M1420-01-0145FEDER-000005-CQM+(Madeira 14-20 Program)the Postdoc Grant(M1420-09-5369-FSE-000001,002458/2015/132)for Carla S.ALVES is also acknowledged。
文摘In this study,the fibers of invasive species Agave americana L.and Ricinus communis L.were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers.Cellulose nanofibers were obtained by two methods,based on either alkaline or acid hydrolysis.The morphology,chemical composition,and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM)together with energy-dispersive X-ray spectroscopy(EDX),dynamic light scattering(DLS),X-ray diffraction(XRD),and Fourier transform infrared(FTIR)spectroscopy.The crystallinity indexes(CIs)of the cellulose nanofibers extracted from A.americana and R.communis were very high(94.1%and 92.7%,respectively).Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T)cells were also performed.The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e.,0-500μg/mL).Our results showed that the nanocellulose extracted from A.americana and R.communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.
文摘In this study, the principal objective is to compare the performances of an air<span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">cooled one cylinder, four</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">stroke direct injection diesel engine using the blends (5% by volume B5, 10% by volume B10) of diesel and biodiesels derived respectively from palm oil, castor oil and raphia sese De Wild oil with pure diesel. All the biodiesels used in this work come from the plant species of the democratic republic of Congo as listed above. The engine performances (power, torque and brake specific consumption)</span><span> </span><span style="font-family:Verdana;">at different engine speeds were determined at both full and partial loads. According to experimental results, the increments in the power output and torque when the mixtures of diesel and biodiesels were used</span><span style="font-family:Verdana;"> and</span><span> </span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> observed. </span><span style="font-family:Verdana;">On</span><span style="font-family:Verdana;"> the other side, the specific fuel consumption of the mixtures is higher than that of pure diesel</span><span> </span><span style="font-family:Verdana;">although the calculated lower heating values </span><span style="font-family:Verdana;">are almost within the same range</span><span style="font-family:Verdana;"> for the all studied fuels. Finally, in partial load 1/1, pure diesel blended with biodiesels B5 derived from castor oil presented high specific brake consumption values compared to the other fuels while B10 from the same oil presents low brake specific consumption values for power greater than 3</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">2 kW.</span>
文摘Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The results showed that the insulation carried out by the L.C main office was a good quality (on thermal aspect), because the resistance of the insulation is so high (i.e. 3940 Mega Ohms under normal conditions). The results showed a lifespan of 50 years at a temperature of 40°C (close to ambient temperature), plus minus 33 years at a temperature of 70°C;plus minus 22 years at a temperature of 100°C and 12 years at a temperature of 160°C. Furthermore, information on chemical attack, the results showed that PVC cables have poor resistance to sulfuric acid attack (having a pH of 1.5 and a density of 1.84 g/cm<sup>3</sup>). LC/Gecamines is able to produce locally a good quality of electrical cables.
文摘Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>3</sub>) to obtain manganese dioxide (MnO<sub>2</sub>). For precipitation tests, a pH ranging from 8 to 10, a time of one to two hours, and a temperature of 25°C and 50°C are the parameters that are considered. The calcination of MnCO<sub>3</sub> is carried out under the following conditions: time (1, 2, 3, and 4 hours) and temperature (370°C, 420°C, and 470°C). It should be noted that the temperature range selected for the calcination tests is based on thermodynamic data obtained using the HSC CHEMISTRY software. The results obtained show an effective recovery of manganese at 25°C, in one hour, with a pH of 8.5 with a precipitation yield and manganese content in the precipitate around 98.43% and 24.21%, respectively. During calcination tests, results show an increase in mass loss, for a constant calcination time, as temperature increases. On the other hand, increasing the calcination time at a given temperature causes an increase in mass loss. However, a significant decrease in mass loss is noted at 3 hours of calcination. The highest mass loss is obtained at a temperature of 470°C after 4 hours of calcination.
