The secretion of melatonin(MT)is obviously different in the younger and the senior sectors of the population,and the maximum plasma concentration of seniors is only half of that in the younger population group.If exog...The secretion of melatonin(MT)is obviously different in the younger and the senior sectors of the population,and the maximum plasma concentration of seniors is only half of that in the younger population group.If exogenous MT can be supplied to senior citizens based on the secretion rate and amount of endogenous MT in the younger population by a bio-mimetic drug delivery system(DDS),an improved therapeutic effect and reduced side effects can be expected.Based upon this hypothesis,the pharmacokinetic parameters of MT,namely,the absorption rate constant(ka),the elimination rate constant(ke),and the ratio of absorption rate(F)to the apparent volume of distribution(V)were obtained by a residual method depending on the plasma concentration curve of immediate release preparations in the healthy younger population.The dose-division method was applied to calculate the cumulative release profiles of MT achieved by oral administration of a controlled release drug delivery system(DDS)to generate plasma MT profiles similar to the physiological level-time profiles.The in vivo release of MT deduced from the healthy younger population physiological MT profiles as the pharmacokinetic output of the bio-mimetic DDS showed a two-phase profile with two different zero order release rates,namely,4.919μg/h during 0-4 h(r=0.9992),and 11.097μg/h during 4-12 h(r=0.9886),respectively.Since the osmotic pump type of DDS generally exhibits a good correlation between in vivo and in vitro release behaviors,an osmotic pump controlled delivery system was designed in combination with dry coating technology targeting on the cumulative release characteristics to mimic the physiological MT profiles in the healthy younger population.The high similarity between the experimental drug release profiles and the theoretical profiles(similarity factor f_(2)>50)and the high correlation between the predicted plasma concentration profiles and the theoretical plasma concentration profiles(r=0.9366,0.9163,0.9264)indicated that a prototype bio-mimetic drug delivery system of MT was established.The similarity factors between the experimental drug release profiles and the theoretical release profile were all larger than 50 both in periods of 0-4 h and 4-12 h,namely,68.8 and 57.3 for the first batch(Batch No.20131031),76.7 and 50.2 for the second batch(Batch No.20131101),and 73.7 and 51.1 for the third batch(Batch No.20131126),respectively.The correlation coefficients between the predicted plasma concentration profiles based on the release profiles of the bio-mimetic DDS and physiological profiles were 0.9366(Batch No.20131031),0.9163(Batch No.20131101),0.9264(Batch No.20131126),respectively.Since the pharmacokinetic profile of MT in any kind of animal differs markedly from that of human beings,it is impossible to test the bio-mimetic DDS in animals directly.Therefore,the predicted pharmacokinetic profile based upon the in vitro release kinetics is an acceptable surrogate for the conventional animal test.In this research,a bio-mimetic DDS for replacement of MT was designed with in silico evaluation.展开更多
Over the past several years,we have been studying the problem of optimally rotating a rigid sphere about its center,where the rotation is actuated by a triplet of external torques acting on the body.The control object...Over the past several years,we have been studying the problem of optimally rotating a rigid sphere about its center,where the rotation is actuated by a triplet of external torques acting on the body.The control objective is to repeatedly direct a suitable radial vector,called the gaze vector,towards a stationary point target in R^(3).The orientation of the sphere is constrained to lie in a suitable submanifold of SO(3).Historically,the constrained rotational movements were studied by physiologists in the nineteenth century,interested in eye and head movements.In this paper we revisit the gaze control problem,where two visual sensors,are tasked to simultaneously stare at a point target in the visual space.The target position changes discretely and the problem we consider is how to reorient the gaze directions of the sensors,along the optimal pathway of the human eyes,to the new location of the target.This is done by first solving an optimal control problem on the human binocular system.Next,we use these optimal control and show that a pan-tilt system can be controlled to follow the gaze trajectory of the human eye requiring a nonlinear static feedback of the pan and tilt angles and their derivatives.Our problem formulation uses a new Riemannian geometric description of the orientation space.The paper also introduces a new,pyramid based interpolation method,to implement the optimal controller.展开更多
This research article introduces an electroactive actuator based on sulfonated chitosan(SCS),ionic liquid and graphene oxide(GO).To maintain the biocompatibility of the chitosan and to increase the actuation performan...This research article introduces an electroactive actuator based on sulfonated chitosan(SCS),ionic liquid and graphene oxide(GO).To maintain the biocompatibility of the chitosan and to increase the actuation performance,a biocompatible ionic liquid such as ethyl,methylimidazolium-trifluoro methane sulfonated(EMI-TFMS)as mobile solvent was used for dry-type actuation.And GO-reinforced SCS films obtained through a simple solvent casting method were extensively investigated because of better electro-chemo-mechanical properties and higher actuation performances.Field-emission scanning electron microscope(FE-SEM),X-ray diffraction(XRD),Fourier transformer infrared spectroscopy(FT-IR),and Raman spectra were used to investigate the interaction mechanism between GO and SCS.The harmonic and step responses of GO and SCS composite actuator show large bending deformations under low electric voltage.展开更多
Semi-invasive blood sampling devices mimic the way female mosquitoes extract blood from a host. They generally consist of a microneedle, a microactuator for needle insertion, a blood extraction mechanism and a blood g...Semi-invasive blood sampling devices mimic the way female mosquitoes extract blood from a host. They generally consist of a microneedle, a microactuator for needle insertion, a blood extraction mechanism and a blood glucose sensor. These devices have great potential to overcome the major disadvantages of several current blood glucose monitoring methods. Over last two decades, extensive research has been made in all of these related fields. More recently, several wearable devices for semi-invasive blood sampling have been developed. This review aims at summarizing the current state-of-the-art development and utilization of such wearable devices for continuous monitoring of blood glucose levels, with a special attention on design considerations, fabrication technologies and testing methods.展开更多
Superhydrophobic(SH)coatings are intended to resist a surface from corrosion and thereby increases the product life duration.It is also a promising solution to save cleaning costs and time by providing self-clea...Superhydrophobic(SH)coatings are intended to resist a surface from corrosion and thereby increases the product life duration.It is also a promising solution to save cleaning costs and time by providing self-clean nature to the surface.This review article provides the most recent updates in designing SH surfaces and their characterizations adopted both in experimental and computational techniques.To gain a comprehensive perspective,the SH surfaces present in nature those are inspiring human beings to mimic such surfaces are introduced at the beginning of this article.Subsequently,different fabrication techniques undertaken recently to design artificial SH surfaces are briefly discussed.Recent progress in computations employed in the development of SH surfaces is then discussed.Next,the limitations in SH surfaces are addressed.Finally,perceptiveness of different strategies and their limitations are presented in the concluding remarks and outlook.Overall,this mini review article brings together and highlights the significant advancements in fabrication of superhydrophobic surfaces which may surely help the early-stage researchers/scientists to plan their work accordingly.展开更多
基金This work was supported from the National Science and Technol-ogy Major Project of the Ministry of Science and Technology of China(2010ZX09401-402)the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists(Prof.Peter York,2013).
文摘The secretion of melatonin(MT)is obviously different in the younger and the senior sectors of the population,and the maximum plasma concentration of seniors is only half of that in the younger population group.If exogenous MT can be supplied to senior citizens based on the secretion rate and amount of endogenous MT in the younger population by a bio-mimetic drug delivery system(DDS),an improved therapeutic effect and reduced side effects can be expected.Based upon this hypothesis,the pharmacokinetic parameters of MT,namely,the absorption rate constant(ka),the elimination rate constant(ke),and the ratio of absorption rate(F)to the apparent volume of distribution(V)were obtained by a residual method depending on the plasma concentration curve of immediate release preparations in the healthy younger population.The dose-division method was applied to calculate the cumulative release profiles of MT achieved by oral administration of a controlled release drug delivery system(DDS)to generate plasma MT profiles similar to the physiological level-time profiles.The in vivo release of MT deduced from the healthy younger population physiological MT profiles as the pharmacokinetic output of the bio-mimetic DDS showed a two-phase profile with two different zero order release rates,namely,4.919μg/h during 0-4 h(r=0.9992),and 11.097μg/h during 4-12 h(r=0.9886),respectively.Since the osmotic pump type of DDS generally exhibits a good correlation between in vivo and in vitro release behaviors,an osmotic pump controlled delivery system was designed in combination with dry coating technology targeting on the cumulative release characteristics to mimic the physiological MT profiles in the healthy younger population.The high similarity between the experimental drug release profiles and the theoretical profiles(similarity factor f_(2)>50)and the high correlation between the predicted plasma concentration profiles and the theoretical plasma concentration profiles(r=0.9366,0.9163,0.9264)indicated that a prototype bio-mimetic drug delivery system of MT was established.The similarity factors between the experimental drug release profiles and the theoretical release profile were all larger than 50 both in periods of 0-4 h and 4-12 h,namely,68.8 and 57.3 for the first batch(Batch No.20131031),76.7 and 50.2 for the second batch(Batch No.20131101),and 73.7 and 51.1 for the third batch(Batch No.20131126),respectively.The correlation coefficients between the predicted plasma concentration profiles based on the release profiles of the bio-mimetic DDS and physiological profiles were 0.9366(Batch No.20131031),0.9163(Batch No.20131101),0.9264(Batch No.20131126),respectively.Since the pharmacokinetic profile of MT in any kind of animal differs markedly from that of human beings,it is impossible to test the bio-mimetic DDS in animals directly.Therefore,the predicted pharmacokinetic profile based upon the in vitro release kinetics is an acceptable surrogate for the conventional animal test.In this research,a bio-mimetic DDS for replacement of MT was designed with in silico evaluation.
文摘Over the past several years,we have been studying the problem of optimally rotating a rigid sphere about its center,where the rotation is actuated by a triplet of external torques acting on the body.The control objective is to repeatedly direct a suitable radial vector,called the gaze vector,towards a stationary point target in R^(3).The orientation of the sphere is constrained to lie in a suitable submanifold of SO(3).Historically,the constrained rotational movements were studied by physiologists in the nineteenth century,interested in eye and head movements.In this paper we revisit the gaze control problem,where two visual sensors,are tasked to simultaneously stare at a point target in the visual space.The target position changes discretely and the problem we consider is how to reorient the gaze directions of the sensors,along the optimal pathway of the human eyes,to the new location of the target.This is done by first solving an optimal control problem on the human binocular system.Next,we use these optimal control and show that a pan-tilt system can be controlled to follow the gaze trajectory of the human eye requiring a nonlinear static feedback of the pan and tilt angles and their derivatives.Our problem formulation uses a new Riemannian geometric description of the orientation space.The paper also introduces a new,pyramid based interpolation method,to implement the optimal controller.
文摘This research article introduces an electroactive actuator based on sulfonated chitosan(SCS),ionic liquid and graphene oxide(GO).To maintain the biocompatibility of the chitosan and to increase the actuation performance,a biocompatible ionic liquid such as ethyl,methylimidazolium-trifluoro methane sulfonated(EMI-TFMS)as mobile solvent was used for dry-type actuation.And GO-reinforced SCS films obtained through a simple solvent casting method were extensively investigated because of better electro-chemo-mechanical properties and higher actuation performances.Field-emission scanning electron microscope(FE-SEM),X-ray diffraction(XRD),Fourier transformer infrared spectroscopy(FT-IR),and Raman spectra were used to investigate the interaction mechanism between GO and SCS.The harmonic and step responses of GO and SCS composite actuator show large bending deformations under low electric voltage.
文摘Semi-invasive blood sampling devices mimic the way female mosquitoes extract blood from a host. They generally consist of a microneedle, a microactuator for needle insertion, a blood extraction mechanism and a blood glucose sensor. These devices have great potential to overcome the major disadvantages of several current blood glucose monitoring methods. Over last two decades, extensive research has been made in all of these related fields. More recently, several wearable devices for semi-invasive blood sampling have been developed. This review aims at summarizing the current state-of-the-art development and utilization of such wearable devices for continuous monitoring of blood glucose levels, with a special attention on design considerations, fabrication technologies and testing methods.
文摘Superhydrophobic(SH)coatings are intended to resist a surface from corrosion and thereby increases the product life duration.It is also a promising solution to save cleaning costs and time by providing self-clean nature to the surface.This review article provides the most recent updates in designing SH surfaces and their characterizations adopted both in experimental and computational techniques.To gain a comprehensive perspective,the SH surfaces present in nature those are inspiring human beings to mimic such surfaces are introduced at the beginning of this article.Subsequently,different fabrication techniques undertaken recently to design artificial SH surfaces are briefly discussed.Recent progress in computations employed in the development of SH surfaces is then discussed.Next,the limitations in SH surfaces are addressed.Finally,perceptiveness of different strategies and their limitations are presented in the concluding remarks and outlook.Overall,this mini review article brings together and highlights the significant advancements in fabrication of superhydrophobic surfaces which may surely help the early-stage researchers/scientists to plan their work accordingly.
