We investigate the impact of different numbers of positive and negative examples on machine learning for sapphire crystals defects prediction. We obtain the models of crystal growth parameters influence on the sapphir...We investigate the impact of different numbers of positive and negative examples on machine learning for sapphire crystals defects prediction. We obtain the models of crystal growth parameters influence on the sapphire crystal growth. For example, these models allow predicting the defects that occur due to local overcooling of crucible walls in the thermal node leading to the accelerated crystal growth. We also develop the prediction models for obtaining the crystal weight, blocks, cracks, bubbles formation, and total defect characteristics. The models were trained on all data sets and later tested for generalization on testing sets, which did not overlap the training set.During training and testing, we find the recall and precision of prediction, and analyze the correlation among the features. The results have shown that the precision of the neural network method for predicting defects formed by local overcooling of the crucible reached 0.94.展开更多
Dengue fever is a disease that is caused by five dengue virus(DENV) serotypes. It is endemic in more than 128 countries. Millions of people are affected by this disease. But still, there is no specific treatment avail...Dengue fever is a disease that is caused by five dengue virus(DENV) serotypes. It is endemic in more than 128 countries. Millions of people are affected by this disease. But still, there is no specific treatment available till now to combat it. Some of the preventive measures using plant extracts showed certain promising ovicidal activity against Aedes aegypti. There are some vaccines as preventive measure and antiviral agents to cure the dengue fever, which are under clinical trials but their results have not been reported or approved yet. Dengvaxia is the only licensed vaccine to prevent dengue fever in some South American countries, but it is not approved by other regulatory authorities worldwide. Scientific research has been going on to find a permanent cure for dengue fever, but till now, no successful invention has been done. There are some general treatments for dengue patient by employing analgesics and fluid replacement; however, specific treatment is needed to overcome the lethal effect of dengue fever. Since this disease has affected millions of people and not much invention has been made in this field; therefore, advancement in dengue therapy is required for the safety and well-being of dengue patients. Herein we collectively describe the different chemotherapeutics agents, alternative methods like vaccines and antiviral agents to prevent and cure this lethal disease. Furthermore, the future perspective for the treatment of dengue is discussed in this review.展开更多
The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagne...The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field (Hs), coercive field (Hc), Weiss temperature (0), and effective magnetic moment (Pelf) are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state (Nf) at Fermi level, Mott's characteristic temperature (To), and activation energy (Ea) in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length (causing an overlap between the oxygen p orbital and iron d orbital) and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.展开更多
This work focused on the fabrication of silicon oxycarbide ceramic(SiOC)foams as well as dense compacts using poly(hydridomethylsiloxane)(PHMS)as a polymer precursor.The room-temperature cross-linking of PHMS was achi...This work focused on the fabrication of silicon oxycarbide ceramic(SiOC)foams as well as dense compacts using poly(hydridomethylsiloxane)(PHMS)as a polymer precursor.The room-temperature cross-linking of PHMS was achieved by the addition of 1,4-diazabicyclo[2.2.2]octane(DABCO)with the release of hydrogen gas as a by-product.This resulted in self-blowing of the polymer precursor at room temperature and thereby offered the possibility of producing SiOC foams without the need of any external blowing agents.We also reported the fabrication of crack-free silicon oxycarbide compacts by cold compaction and pyrolysis route using polyvinyl alcohol(PVA)as a processing additive.Cylindrical-shaped pellets were pyrolysed at 1300℃in argon atmosphere with a ceramic yield of approximately 85%.Increased resistance to phase separation and crystallization up to 1400℃was attributed to the presence of large volume fraction of free carbon in the material which was confirmed by Raman spectroscopy.展开更多
During last two decades,transition-metal catalyzed asymmetric reactions under continuous flow system have attracted a widespread attention.With its prominent advantages including higher safety and efficiency,precise c...During last two decades,transition-metal catalyzed asymmetric reactions under continuous flow system have attracted a widespread attention.With its prominent advantages including higher safety and efficiency,precise control,better heat/mass transfer,easier scale-up and better sustainability,it has impressed both the academia and related industries.However,comparing with the prosperous development of transition-metal catalyzed asymmetric reactions in batch,utilization of this type of chemistry under continuous flow is still at an early stage.To inspire more potential industrial application and further studies of this chemistry in flow,this review sum-marized the recent advances of transition-metal catalyzed asymmetric reactions under continuous flow.Moreover,we further discussed the encountered challenges including reactor engineering,catalyst design,catalyst deacti-vation,pressure drop,clogging,side reactions etc.,as well as their corresponding solutions and achievements in this mini-review.展开更多
基金supported by the Russian Foundation for Basic Research Projects under Grant No.16-52-48016ИНД_оми(R.Kumar and A.V.Filimonov)。
文摘We investigate the impact of different numbers of positive and negative examples on machine learning for sapphire crystals defects prediction. We obtain the models of crystal growth parameters influence on the sapphire crystal growth. For example, these models allow predicting the defects that occur due to local overcooling of crucible walls in the thermal node leading to the accelerated crystal growth. We also develop the prediction models for obtaining the crystal weight, blocks, cracks, bubbles formation, and total defect characteristics. The models were trained on all data sets and later tested for generalization on testing sets, which did not overlap the training set.During training and testing, we find the recall and precision of prediction, and analyze the correlation among the features. The results have shown that the precision of the neural network method for predicting defects formed by local overcooling of the crucible reached 0.94.
文摘Dengue fever is a disease that is caused by five dengue virus(DENV) serotypes. It is endemic in more than 128 countries. Millions of people are affected by this disease. But still, there is no specific treatment available till now to combat it. Some of the preventive measures using plant extracts showed certain promising ovicidal activity against Aedes aegypti. There are some vaccines as preventive measure and antiviral agents to cure the dengue fever, which are under clinical trials but their results have not been reported or approved yet. Dengvaxia is the only licensed vaccine to prevent dengue fever in some South American countries, but it is not approved by other regulatory authorities worldwide. Scientific research has been going on to find a permanent cure for dengue fever, but till now, no successful invention has been done. There are some general treatments for dengue patient by employing analgesics and fluid replacement; however, specific treatment is needed to overcome the lethal effect of dengue fever. Since this disease has affected millions of people and not much invention has been made in this field; therefore, advancement in dengue therapy is required for the safety and well-being of dengue patients. Herein we collectively describe the different chemotherapeutics agents, alternative methods like vaccines and antiviral agents to prevent and cure this lethal disease. Furthermore, the future perspective for the treatment of dengue is discussed in this review.
文摘The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field (Hs), coercive field (Hc), Weiss temperature (0), and effective magnetic moment (Pelf) are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state (Nf) at Fermi level, Mott's characteristic temperature (To), and activation energy (Ea) in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length (causing an overlap between the oxygen p orbital and iron d orbital) and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.
基金This work was supported financially by Indian Space Research Organisation and their support is gratefully acknowledged.
文摘This work focused on the fabrication of silicon oxycarbide ceramic(SiOC)foams as well as dense compacts using poly(hydridomethylsiloxane)(PHMS)as a polymer precursor.The room-temperature cross-linking of PHMS was achieved by the addition of 1,4-diazabicyclo[2.2.2]octane(DABCO)with the release of hydrogen gas as a by-product.This resulted in self-blowing of the polymer precursor at room temperature and thereby offered the possibility of producing SiOC foams without the need of any external blowing agents.We also reported the fabrication of crack-free silicon oxycarbide compacts by cold compaction and pyrolysis route using polyvinyl alcohol(PVA)as a processing additive.Cylindrical-shaped pellets were pyrolysed at 1300℃in argon atmosphere with a ceramic yield of approximately 85%.Increased resistance to phase separation and crystallization up to 1400℃was attributed to the presence of large volume fraction of free carbon in the material which was confirmed by Raman spectroscopy.
基金This work is supported by Shenzhen Fundamental Research Projects(No.JCYJ20190806142203709)We are also grateful to the startup of Harbin Institute of Technology(Shenzhen)through the Talent Development Starting Fund from Shenzhen Government(No.HA11409030).
文摘During last two decades,transition-metal catalyzed asymmetric reactions under continuous flow system have attracted a widespread attention.With its prominent advantages including higher safety and efficiency,precise control,better heat/mass transfer,easier scale-up and better sustainability,it has impressed both the academia and related industries.However,comparing with the prosperous development of transition-metal catalyzed asymmetric reactions in batch,utilization of this type of chemistry under continuous flow is still at an early stage.To inspire more potential industrial application and further studies of this chemistry in flow,this review sum-marized the recent advances of transition-metal catalyzed asymmetric reactions under continuous flow.Moreover,we further discussed the encountered challenges including reactor engineering,catalyst design,catalyst deacti-vation,pressure drop,clogging,side reactions etc.,as well as their corresponding solutions and achievements in this mini-review.