Performance assessment of a three-dimensional printed porous media produced by selective laser melting technology for the optimization of loop heat pipe wicks

The primary wick in a loop heat pipe device is a key component that is central to the operation of the device. Both high permeability and capillary pumping capacity, two properties highly dependent on wick structure, are strongly desirable for a satisfactory thermal performance. In this paper, selective laser melting (SLM), a three-dimensional (3D) printing technology, is used to create a primary wick for an 80 W heat transfer application. The permeability and capillarity values of this wick, experimentally measured, are compared with those built with the most widely used technologies nowadays, such as powder sintering and meshes. In this study, the SLM scaffold is shown to satisfy the minimum values required by the application in terms of capillarity and permeability: 0.031 mm/s and 4 × 10−12 m2, respectively. Our comparative study revealed that the wick produced with the SLM technology presented higher values of permeability, by two orders of magnitude, and slightly higher capillary figures than those corresponding to powder sintering for such application. However, it had capillary values well below those of a stainless-steel mesh. The hydraulic behavior of the SLM wick was better than that of the sintered copper powder, because it not only met the above-mentioned specifications, but it also improved its performance

The Effects of Tau Proteins on Microtubule Mechanics and Molecular Motor Transport

Microtubules are an essential component of the cytoskeleton that provide structural integrity and facilitate important functions in cells. In this work, I will explore several aspects of microtubule mechanics and function using a wide range of biophysical techniques. I am particularly interested in the effects of stabilizing agents, including small molecule inhibitors of microtubule dynamics (such as taxol or epothilone), and microtubule-binding proteins, such as tau. First, using advanced spectral analytical techniques, we studied the effects of tau proteins on the mechanical properties of single microtubule (MT) filaments under controlled in vitro conditions. We found that the short forms of 3-repeat (3R) and 4-repeat (4R) wild-type (WT) tau proteins reduce the stiffness of taxol-assembled MTs compared to a no tau control, despite the fact that the microtubule diameter is known to increase when these tau proteins bind. In contrast, single point tau mutants P301L, R406W and ΔN296, which are all linked to devastating neurological diseases, do not have significant effects on microtubule stiffness compared to a no tau control, raising interesting questions about possible mechanical origins of tauopathy diseases.Next, we examined the effects of tau proteins on in vitro transport properties of kinesin-bound cargoes on microtubules. In comparison to the no tau control, kinesin-bound quantum dot cargoes had lower velocity and shorter run lengths in the presence of tau when moving on taxol-assembled microtubules. Most of the single point tau mutants that we tested showed similar slowing of cargo translocation, with speed reductions similar to those observed with WT tau. One exception was the 4R short R406W mutant tau, in which the velocities of kinesin-bound cargoes were significantly lower than in WT case. The disease mechanism for mutant has been particularly puzzling, so our results may suggest a more prominent role in disruption of axonal transport than was previously appreciated.Next, we investigated the effects of microtubule-stabilizing chemicals epothilone-A and -B on 1) microtubule mechanics, 2) the transport properties of kinesins and 3) the ability of WT tau proteins modify the stiffness of microtubules assembled with epothilone. We found that microtubules assembled in the presence of epothilone-A or -B were less stiff compared to taxol-assembled MTs, and the addition of WT tau further reduced the stiffness. However, the differences in stiffness/persistence length between epothilone-assembled microtubules and taxol-assembled microtubules diminished after the addition of WT tau. Kinesin translocation speed was sensitive to the type of stabilizing chemical, and the changes in velocity in the presence of tau were also depended on the assembly condition. Epothiolone and taxol compunds are both frequently used in cancer chemotherapies, and our results shed light on the possible molecular mechanisms of neurological side effects (such as debilitating nerve pain) when these agents are used.Lastly, we looked at the effects of tau on intracellular trafficking in COS-7 cells. We found that the microtubule network in the cells were dramatically modified after the introduction of tau via transient transfection, with substantial bundling, aggregation and membrane-association in the presence of tau. However, there were no obvious differences in the microtubule network structures between cells that were transfected with mutant tau and wild-type tau. Interestingly, despite the major modification of the cytoskeletal structures in the presence of tau, the measured velocities of lysosomes in directed transport in cells that were transfected with tau were not significantly different compared to the lysosome velocities in cells with no tau.Taken together, studies provide important new insights into how tau proteins and other small molecule stabilizers modulate the mechanical and functional properties of cytoskeletal microtubules and how misregulations in tau may be related to the development of neurodegeneration and dementia diseases

Factors affecting sustainability of smart city services in China:From the perspective of citizens’ sense of gain

The citizen-centric smart city has become an essential paradigm for dealing with the problems caused by rapid urbanization. The Chinese government proposed enhancing citizens' sense of gain to achieve the citizen-centric development goal. To develop a more realistic improving path for the sustainability of smart city services (SCS), it is necessary to clarify the factors that affect citizens' sense of gain of smart city services (CSGSCS). To achieve this objective, 9 hypotheses were developed based on the modified expectation confirmation theory. Hypothesis testing, mediating effect testing, and heterogeneity analysis was conducted based on data collected from Nanjing citizens. The results indicate that: 1) Expectation-Perception Performance, including Content of SCS, Channel of SCS, and Support of SCS, all have positive direct effects on CSGSCS; 2) Expectation Confirmation directly affects CSGSCS and mediates the positive effect of the Expectation-Perception Performance on CSGSCS; 3) Heterogeneity of age and usage frequency have significant effects on CSGSCS. Finally, three policy implications were proposed, including encouraging citizens to participate in SCS supply, bridging the digital divide created by SCS, and improving the policy and legal system on SCS. This research enriches the academic framework and provides guidance for sustainable supply of SCS in similar cities around the world.</p

Reinforcement Causal Structure Learning on Order Graph

Learning directed acyclic graph (DAG) that describes the causality of observed data is a very challenging but important task. Due to the limited quantity and quality of observed data, and non-identifiability of causal graph, it is almost impossible to infer a single precise DAG. Some methods approximate the posterior distribution of DAGs to explore the DAG space via Markov chain Monte Carlo (MCMC), but the DAG space is over the nature of super-exponential growth, accurately characterizing the whole distribution over DAGs is very intractable. In this paper, we propose {Reinforcement Causal Structure Learning on Order Graph} (RCL-OG) that uses order graph instead of MCMC to model different DAG topological orderings and to reduce the problem size. RCL-OG first defines reinforcement learning with a new reward mechanism to approximate the posterior distribution of orderings in an efficacy way, and uses deep Q-learning to update and transfer rewards between nodes. Next, it obtains the probability transition model of nodes on order graph, and computes the posterior probability of different orderings. In this way, we can sample on this model to obtain the ordering with high probability. Experiments on synthetic and benchmark datasets show that RCL-OG provides accurate posterior probability approximation and achieves better results than competitive causal discovery algorithms.Comment: Accepted by the Thirty-Seventh AAAI Conference on Artificial Intelligence(AAAI2023

Factors affecting sustainability of smart city services in China:From the perspective of citizens’ sense of gain

The citizen-centric smart city has become an essential paradigm for dealing with the problems caused by rapid urbanization. The Chinese government proposed enhancing citizens' sense of gain to achieve the citizen-centric development goal. To develop a more realistic improving path for the sustainability of smart city services (SCS), it is necessary to clarify the factors that affect citizens' sense of gain of smart city services (CSGSCS). To achieve this objective, 9 hypotheses were developed based on the modified expectation confirmation theory. Hypothesis testing, mediating effect testing, and heterogeneity analysis was conducted based on data collected from Nanjing citizens. The results indicate that: 1) Expectation-Perception Performance, including Content of SCS, Channel of SCS, and Support of SCS, all have positive direct effects on CSGSCS; 2) Expectation Confirmation directly affects CSGSCS and mediates the positive effect of the Expectation-Perception Performance on CSGSCS; 3) Heterogeneity of age and usage frequency have significant effects on CSGSCS. Finally, three policy implications were proposed, including encouraging citizens to participate in SCS supply, bridging the digital divide created by SCS, and improving the policy and legal system on SCS. This research enriches the academic framework and provides guidance for sustainable supply of SCS in similar cities around the world.</p

B2RL: An open-source Dataset for Building Batch Reinforcement Learning

Batch reinforcement learning (BRL) is an emerging research area in the RL community. It learns exclusively from static datasets (i.e. replay buffers) without interaction with the environment. In the offline settings, existing replay experiences are used as prior knowledge for BRL models to find the optimal policy. Thus, generating replay buffers is crucial for BRL model benchmark. In our B2RL (Building Batch RL) dataset, we collected real-world data from our building management systems, as well as buffers generated by several behavioral policies in simulation environments. We believe it could help building experts on BRL research. To the best of our knowledge, we are the first to open-source building datasets for the purpose of BRL learning

Thermoelectric property studies on thallium-doped lead telluride prepared by ball milling and hot pressing

Thallium doping into lead telluride has been demonstrated to increase the dimensionless thermoelectric figure-of-merit (ZT) by enhancing Seebeck coefficient due to the creation of resonant states close to Fermi level without affecting the thermal conductivity. However, the process is tedious, energy consuming, and small in quantities since it involves melting, slow cooling for crystal growth, long time annealing, post-crushing and hot pressing. Here we show that a similar ZT value about 1.3 at 400 °C is achieved on bulk samples with grain sizes of 3–7 μm by ball milling a mixture of elemental thallium, lead, and tellurium and then hot pressing the ball milled nanopowders

A Multi-objective Optimization Algorithm for Multiple Home Users Intelligent Power Management and Control Based on Pareto and Nash Equilibrium Game

A multi-objective optimization model for multiple home users intelligent power management and control is proposed. A photovoltaic power model, an electric vehicle battery model and a load model are developed first, and then a strategy of home intelligent power management is presented based on battery operation and PV spontaneous self-use. Secondly, a multi-objective optimization model of multiple home users intelligent power management, including the user comfort, economy and optimization of load curve, is provided under the constraints. Then using a multi-objective optimization algorithm and Nash equilibrium game theory to solve the multi-objective problem. Finally, the 100-home power management and control simulation case show that the presented algorithm can improve the comfort and the economy of users effectively, but also help the power grid to peak load shifting

Cumulative Evidence for Relationships Between 8q24 Variants and Prostate Cancer

Multiple independent cancer susceptibility loci at chromosome 8q24 have been identified by GWAS (Genome-wide association studies). Forty six articles including 60,293 cases and 62,971 controls were collected to conduct a meta-analysis to evaluate the associations between 21 variants in 8q24 and prostate cancer risk. Of the 21 variants located in 8q2\5 were significantly associated with the risk of prostate cancer. In particular, both homozygous AA and heterozygous CA genotypes of rs16901979, as well as the AA and CA genotypes of rs1447295, were associated with the risk of prostate cancer. Our study showed that variants in the 8q24 region are associated with prostate cancer risk in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the role of the 8q24 variants involved in the etiology of prostate cancer

Multi-normal-mode splitting of a cavity in the presence of atoms -- towards the superstrong coupling regime

Multi-normal-mode splitting peaks are experimentally observed in a system with Doppler-broadened two-level atoms inside a relatively long optical cavity. In this system, the atoms-cavity interaction can reach the ``superstrong coupling" condition with atoms-cavity coupling strength $g\sqrt{N}$ to be near or larger than the cavity free-spectral range $\Delta_{FSR}$. In such case, normal-mode splitting can occur in many cavity longitudinal modes to generate the multi-normal-mode splitting peaks, which can be well explained by the linear dispersion enhancement due to the largely increased atomic density in the cavity. Many new interesting phenomena might come out of this superstrong atoms-cavity coupling regime.Comment: 4 pages, 5 figures. appear in Phys. Rev.