Achieving the activation of drugs within cellular systems may provide targeted therapies. Here we construct a tumour-selective cascade activatable self-detained system (TCASS) and incorporate imaging ...probes and therapeutics. We show in different mouse models that the TCASS system accumulates in solid tumours. The molecules show enhanced accumulation in tumour regions via the effect of recognition induced self-assembly. Analysis of the molecular penetration in tumour tissue shows that in vivo self-assembly increases the penetration capability compared to typical soft or hard nanomaterials. Importantly, the in vivo self-assembled molecules exhibit a comparable clearance pathway to that of small molecules, which are excreted from organs of the reticuloendothelial system (liver and kidney), while are relatively slowly eliminated from tumour tissues. Finally, this system, combined with the NIR probe, shows high specificity and sensitivity for detecting bladder cancer in isolated intact patient bladders.
Tumor complexity makes the development of highly sensitive tumor imaging probes an arduous task. Here, we construct a peptide‐based near‐infrared probe that is responsive to fibroblast activation ...protein‐α (FAP‐α), and specifically forms nanofibers on the surface of cancer‐associated fibroblasts (CAFs) in situ. The assembly/aggregation‐induced retention (AIR) effect results in enhanced accumulation and retention of the probe around the tumor, resulting in a 5.5‐fold signal enhancement in the tumor 48 h after administration compared to that of a control molecule that does not aggregate. The probe provides a prolonged detectable window of 48 h for tumor diagnosis. The selective assembly of the probe results in a signal intensity over four‐ and fivefold higher in tumor than in the liver and kidney, respectively. With enhanced tumor imaging capability, this probe can visualize small tumors around 2 mm in diameter.
Image of health: A peptide probe labeled with a near‐infrared dye has been developed that can be specifically tailored with a fibroblast activation protein‐α and then self‐assembled in situ into nanofibers on the surface of cancer‐associated fibroblasts. The selective assembly of the probe has resulted in tumor imaging with high sensitivity and specificity, with tumors as small as 2 mm in diameter visualized.
In this paper, we establish the theory of basic reproduction ratio
R
0
for a large class of time-delayed compartmental population models in a periodic environment. It is proved that
R
0
serves as a ...threshold value for the stability of the zero solution of the associated periodic linear systems. As an illustrative example, we also apply the developed theory to a periodic SEIR model with an incubation period and obtain a threshold result on its global dynamics in terms of
R
0
.
Real-time imaging of the tumour boundary is important during surgery to ensure that sufficient tumour tissue has been removed. However, the current fluorescence probes for bioimaging suffer from poor ...tumour specificity and narrow application of the imaging window used. Here, we report a bioactivated in vivo assembly (BIVA) nanotechnology, demonstrating a general optical probe with enhanced tumour accumulation and prolonged imaging window. The BIVA probe exhibits active targeting and assembly induced retention effect, which improves selectivity to tumours. The surface specific nanofiber assembly on the tumour surface increases the accumulation of probe at the boundary of the tumor. The blood circulation time of the BIVA probe is prolonged by 110 min compared to idocyanine green. The assembly induced metabolic stability broaden the difference between the tumor and background, obtaining a delayed imaging window between 8-96 h with better signal-to-background contrast (>9 folds). The fabricated BIVA probe permits precise imaging of small sized (<2 mm) orthotopic pancreatic tumors in vivo. The high specificity and sensitivity of the BIVA probe may further benefit the intraoperative imaging in a clinical setting.
In the upcoming decades, connected vehicles will join regular vehicles to appear on roads, and the characteristics of traffic flow will be changed accordingly. To model the heterogeneous traffic ...mixing regular and connected vehicles, a generic car-following framework is first proposed in this paper. A linear stability condition is theoretically derived, which indicates that the stability of the heterogeneous traffic is closely related to the penetration rate and the spatial distribution of connected vehicles. The generic car-following framework is applied by taking the Intelligent Driver Model as an example, and it is shown that connected vehicles can obviously enhance the stability of traffic flow and improve traffic efficiency in particular when traffic is in congestion. Moreover, a driver assistance strategy based on distributed feedback control is developed for connected vehicles, and the simulation results show that the proposed driver assistance strategy performs satisfactorily in stabilizing traffic as well as improving traffic efficiency.
In this paper, we develop the theory of basic reproduction ratios
R
0
for abstract functional differential systems in a time-periodic environment. It is proved that
R
0
-
1
has the same sign as the ...exponential growth bound of an associated linear system. Then we apply it to a time-periodic Lyme disease model with time-delay and obtain a threshold type result on its global dynamics in terms of
R
0
.
A new high performance stiff epoxy vitrimer based on siloxane equilibration has been fabricated in a simple way in which a polysiloxane oligomer containing aminopropyl side groups and catalytic ...potassium silanolate end groups was synthesized and used as a curing agent. The viscoelastic properties of the cured epoxy can be controlled by varying the concentration of potassium silanolate groups and the vitrimer possessing a complete stress relaxation behavior can be prepared, with relaxation times ranging from 376.8 s at 90 °C to 40.2 s at 170 °C. Due to the dynamic siloxane equilibration of polysiloxane catalyzed by potassium silanolate groups, this epoxy vitrimer exhibits excellent self-healing and recycling abilities. It can self-repair with a high healing efficiency, and be recycled at 130 °C within 40 min, retaining its original mechanical and thermal properties after at least four recycling cycles. Furthermore, such a material exhibits simultaneously a high service temperature (a glass transition temperature of 83 °C and an initial degradation temperature of 358 °C) and a strong (a stress at break of 46.6 MPa) and stiff (Young's modulus of 2.2 GPa) nature.
We study a Lotka–Volterra type reaction–diffusion–advection system, which describes the competition for the same resources between two aquatic species undergoing different dispersal strategies, as ...reflected by their diffusion and/or advection rates. For the non-advective case, this problem was solved by Dockery et al. 9, and recently He and Ni 14 provided a further classification on the global dynamics for a more general model. However, the key ideas developed in 9,14 do not appear to work when advection terms are involved. By assuming the resource function is decreasing in the spatial variable, we establish the non-existence of co-existence steady state and perform sufficient analysis on the local stability of two semi-trivial steady states, where new techniques were introduced to overcome the difficulty caused by the non-analyticity of stationary solutions as well as the diffusion–advection type operators. Combining these two aspects with the theory of monotone dynamical systems, we finally obtain the global dynamics, which suggests that the competitive exclusion principle holds in most situations.
Nous étudions un systéme de réaction-diffusion-advection de type Lotka-Volterra, qui décrit la compétition pour les mêmes ressources entre deux espéces aquatiques ayant différentes stratégies de dispersion, reflétées par leurs taux de diffusion et/ou d'advection. Le cas sans advection a été traité par Dockery et al. 9, et récemment He et Ni 14 ont également donné une classification de la dynamique globale pour un modéle plus général. Cependant, les idées clés développées dans 9,14 ne semblent pas fonctionner en présence de termes d'advection. En supposant que les ressources sont décroissantes par rapport á la variable d'espace, nous montrons la non-existence d'état stationnaire avec co-existence des espéces et analysons la stabilité locale de deux états stationnaires semi-triviaux. De nouvelles techniques sont introduites pour contourner la difficulté créée par la non-analyticité des solutions stationnaires et par des opérateurs de type diffusion-advection. En combinant ces deux aspects avec la théorie des systémes dynamiques monotones, nous obtenons finalement la dynamique globale, qui suggére que le principe d'exclusion par compétition se produit dans la plupart des situations.
1,2‐Bisphosphines have been identified as one class of important and powerful chiral ligands in asymmetric catalysis with transition metals. Herein, a copper(I)‐catalyzed asymmetric ...hydrophosphination of α,β‐unsaturated phosphine sulfides was developed with the assistance of “soft–soft” interaction between copper(I)‐catalyst and the phosphine sulfide moiety, which afforded 1,2‐bisphosphine derivatives with diversified electronic nature and steric hindrance in high to excellent yields with high to excellent enantioselectivity. Moreover, the challenging catalytic asymmetric hydrophosphination/protonation reaction was achieved with excellent enantioselectivity. Strikingly, the dynamic kinetic resolution of racemic diarylphosphines was also successfully carried out with high to excellent diastereo‐ and enantioselectivities. Interestingly, the nucleophilic copper(I)‐diphenylphosphide species was characterized by 31P NMR spectrum and mass spectrum. At last, three products were transformed to chiral 1,2‐bisphosphines, which were employed as ligands in Rh‐catalyzed asymmetric hydrogenation of α‐amino‐α,β‐unsaturated ester. The α‐amino acid derivative was produced in high enantioselectivity, which demonstrated the utility of the present methodology.
A catalytic asymmetric conjugate hydrophosphination of α,β‐unsaturated phosphine sulfides with diarylphosphines allows rapid construction of chiral 1,2‐bisphosphine derivatives with diversified electronic nature and steric hindrance. This reaction is facilitated by the “soft–soft” interaction between copper(I) catalysts and phosphine sulfides.
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