Abstract
Recently, theoretical studies show that layered HfTe
5
is at the boundary of weak & strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice ...parameters. The topological properties of 3D stacked HfTe
5
are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic & crystal structures for HfTe
5
with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe
5
crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe
5
transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe
5
is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.
SCN1A is the most relevant epilepsy gene. Mutations of SCN1A generate phenotypes ranging from the extremely severe form of Dravet syndrome (DS) to a mild form of generalized epilepsy with febrile ...seizures plus (GEFS+). Mosaic SCN1A mutations have been identified in rare familial DS. It is suspected that mosaic mutations of SCN1A may cause other types of familial epilepsies with febrile seizures (FS), which are more common clinically. Thus, we screened SCN1A mutations in 13 families with partial epilepsy with antecedent febrile seizures (PEFS+) using denaturing high‐performance liquid chromatography and sequencing. The level of mosaicism was further quantified by pyrosequencing. Two missense SCN1A mutations with mosaic origin were identified in two unrelated families, accounting for 15.4% (2/13) of the PEFS+ families tested. One of the mosaic carriers with ∼25.0% mutation of c.5768A>G/p.Q1923R had experienced simple FS; another with ∼12.5% mutation of c.4847T>C/p.I1616T was asymptomatic. Their heterozygous children had PEFS+. Recurrent transmission occurred in both families, as noted in most of the families with germline mosaicism reported previously. The two mosaic mutations identified in this study are less destructive missense, compared with the more destructive truncating and splice‐site mutations identified in the majority of previous studies. This is the first report of mosaic SCN1A mutations in families with probands that do not exhibit DS, but manifest only a milder phenotype. Therefore, such families with mild cases should be approached with caution in genetic counseling and the possibility of mosaicism origin associated with high recurrence risk should be excluded.
Cells use compartmentalization of enzymes as a strategy to regulate metabolic pathways and increase their efficiency
. The α- and β-carboxysomes of cyanobacteria contain ribulose-1,5-bisphosphate ...carboxylase/oxygenase (Rubisco)-a complex of eight large (RbcL) and eight small (RbcS) subunits-and carbonic anhydrase
. As HCO
can diffuse through the proteinaceous carboxysome shell but CO
cannot
, carbonic anhydrase generates high concentrations of CO
for carbon fixation by Rubisco
. The shell also prevents access to reducing agents, generating an oxidizing environment
. The formation of β-carboxysomes involves the aggregation of Rubisco by the protein CcmM
, which exists in two forms: full-length CcmM (M58 in Synechococcus elongatus PCC7942), which contains a carbonic anhydrase-like domain
followed by three Rubisco small subunit-like (SSUL) modules connected by flexible linkers; and M35, which lacks the carbonic anhydrase-like domain
. It has long been speculated that the SSUL modules interact with Rubisco by replacing RbcS
. Here we have reconstituted the Rubisco-CcmM complex and solved its structure. Contrary to expectation, the SSUL modules do not replace RbcS, but bind close to the equatorial region of Rubisco between RbcL dimers, linking Rubisco molecules and inducing phase separation into a liquid-like matrix. Disulfide bond formation in SSUL increases the network flexibility and is required for carboxysome function in vivo. Notably, the formation of the liquid-like condensate of Rubisco is mediated by dynamic interactions with the SSUL domains, rather than by low-complexity sequences, which typically mediate liquid-liquid phase separation in eukaryotes
. Indeed, within the pyrenoids of eukaryotic algae, the functional homologues of carboxysomes, Rubisco adopts a liquid-like state by interacting with the intrinsically disordered protein EPYC1
. Understanding carboxysome biogenesis will be important for efforts to engineer CO
-concentrating mechanisms in plants
.
•Formulate the no-toll equilibrium (NTE) and the congestion and environmental toll (CET) equilibrium problems with heterogeneous users as unconstrained optimization problems.•Modify the BFGS method ...to solve these problems.•Formulate the optimal congestion toll and CET design problems as bi-level programs.•Develop the double BFGS method to solve the two bi-level programs.
We design a congestion and environmental toll (CET) scheme for the morning commute with heterogeneous users in a single OD network with parallel routes. The designed toll scheme relies upon the concept of marginal-cost pricing and is anonymous. The Henderson approach is used to model road congestion and the tolling problem to examine commuter's arrival time and route choice at the CET equilibrium (CETE). Linear interpolation is applied to approximate the emission cost function and the resulting CETE problem is formulated as an unconstrained optimization problem, which is solved by the modified Broyden-Fletcher-Goldfarb-Shanno (BFGS) method. Unlike the existing approach, this novel approach does not require that the arrival of each group of commuters at the destination at the equilibrium follows a predetermined order, and can handle non-monotone (emission) cost function. As two special cases, no-toll equilibrium (NTE) and the congestion toll equilibrium (CTE) are also examined, and the two resultant equilibrium problems are formulated and solved by the same approach. This approach is shown to be more efficient than the existing approach. Bi-level programming models are proposed to formulate the optimal congestion toll and CET design problems, in which the CTE and CETE problems are the corresponding lower level problem. These models are solved by the double BFGS method, which uses a classical BFGS method to solve the upper level model and the proposed BFGS method to solve the lower level model. Finally, numerical examples are provided to illustrate the properties of the models and the efficiency of the proposed solution algorithms.
Understanding the photoexcited carrier-relaxation actions in ultrasmall black phosphorus quantum dots (BPQDs) will play a crucial role in the fields of electronics and optoelectronics. Herein, we ...report the ultraviolet (UV) saturable absorption and ultrafast photoexcited carrier-relaxation dynamics of BPQDs. The ultrasmall BPQDs are synthesized using a facile liquid-exfoliation method and possess a diameter of 3.8 ± 0.6 nm and a thickness of 1.5 ± 0.4 nm. Femtosecond open-aperture (OA) Z-scan measurements showed typical saturable absorption properties in the UV band. A negative nonlinear optical (NLO) absorption coefficient of -(1.4 ± 0.3) × 10
cm GW
and a saturable intensity of 6.6 ± 1.3 GW cm
were determined. Using a degenerate pump-probe technique, an ultrafast photoexcited carrier-recombination time was observed in the range of 216-305 fs, which was 3 orders of magnitude faster than that of BP nanosheets. Such an ultrafast relaxation component may be attributable to the edge- and step-mediated recombination and was confirmed by our density functional theory (DFT) calculations. This work provides fundamental insight into the underlying mechanism of the photoexcited carrier relaxation dynamic action in BPQDs which can enable UV photonic devices.
Propose the concept of park-and-ride-sharing (P&RS) and develop a bottleneck model with P&RS.•Discover three possible equilibrium ride-sharing matching patterns and three possible equilibrium traffic ...flow patterns to the proposed bottleneck model.•Design three parking charge schemes to minimize total system cost.•Analytically determine the optimal parking charge schemes and the corresponding optimal allocation scheme of bottleneck capacity to HOV lanes.•Illustrate the effect of P&RS on travelers’ travel choice and the performance of the proposed parking charge schemes.
In this paper, park-and-ride-sharing (P&RS) is proposed to manage morning peak hour congestion in a monocentric linear city, where there is a multilane highway with a single bottleneck connecting the residential area and the central business district (CBD). To realize ride-sharing matching, a ride-sharing parking lot (RSPL) and a ride-sharing meeting point (RSMP) are set up somewhere between the origin and the bottleneck. To encourage ride-sharing participation, the lanes of the highway are physically divided into high occupancy vehicle (HOV) and general purpose (GP) lanes for only ride-sharing vehicles and non-ride-sharing vehicles, respectively. The user equilibrium principle in terms of generalized travel cost is adopted to formulate commuters’ mode choice and arrival time choice at the RSMP. It is demonstrated that there exist three possible equilibrium ride-sharing matching patterns and three possible equilibrium traffic flow patterns. All possible equilibrium ride-sharing matching and traffic flow patterns are analytically derived. In addition, to minimize total system cost (TSC), three break-even parking charge schemes are designed under the case that all parking lots are managed by the government. The optimal allocation scheme of bottleneck capacity to HOV lanes under each parking charge scheme is analytically derived. Finally, numerical examples are provided to illustrate the properties of the proposed bottleneck model with P&RS and the effectiveness of the designed parking charge schemes.
•This paper introduces a bi-objective turning restriction design problem.•Vehicle emissions and total travel time are considered in the upper level problem.•Modified artificial bee colony (ABC) is ...developed to obtain Pareto optimal solutions.•Incorporating crossover operators into ABC can improve its performance.•Traffic information provision does have an impact on the number of optimal designs.
This paper introduces a bi-objective turning restriction design problem (BOTRDP), which aims to simultaneously improve network traffic efficiency and reduce environmental pollution by implementing turning restrictions at selected intersections. A bi-level programming model is proposed to formulate the BOTRDP. The upper level problem aims to minimize both the total system travel time (TSTT) and the cost of total vehicle emissions (CTVE) from the viewpoint of traffic managers, and the lower level problem depicts travelers’ route choice behavior based on stochastic user equilibrium (SUE) theory. The modified artificial bee colony (ABC) heuristic is developed to find Pareto optimal turning restriction strategies. Different from the traditional ABC heuristic, crossover operators are captured to enhance the performance of the heuristic. The computational experiments show that incorporating crossover operators into the ABC heuristic can indeed improve its performance and that the proposed heuristic significantly outperforms the non-dominated sorting genetic algorithm (NSGA) even if different operators are randomly chosen and used in the NSGA as in our proposed heuristic. The results also illustrate that a Pareto optimal turning restriction strategy can obviously reduce the TSTT and the CTVE when compared with those without implementing the strategy, and that the number of Pareto optimal turning restriction designs is smaller when the network is more congested but greater network efficiency and air quality improvement can be achieved. The results also demonstrate that traffic information provision does have an impact on the number of Pareto optimal turning restriction designs. These results should have important implications on traffic management.
•This paper introduces an operating problem in a bimodal transport system.•In-vehicle congestion cost functions are assumed to be unknown.•The distribution of perceived travel cost errors is also ...assumed to be unknown.•The paper proposes two convergent trial-and-error operation schemes for the problem.•The first scheme determines bus fares to minimize total system cost.•The second one determines both the bus fares and frequencies to maximize the operating profit.
We concern the modal choice of commuters in a transport system comprising a highway, which is only used by autos, in parallel to a transit line, which is only used by buses. In the transport system, the in-vehicle congestion of passengers in bus carriages is treated as a negative externality cost of affecting the modal choice of commuters and commuters choose their travel modes according to the perceived travel costs of transport modes. We propose two trial-and-error operation schemes for the transport system without resorting to both the function of in-vehicle congestion costs and the distribution of perceived travel cost errors. In the first operation scheme, the manager (or the government) determines the transit fare charged from (or financial subsidy to) bus users from period to period so as to minimize the system time cost of the transport system. The second operation scheme is established from the viewpoint of a private firm that operates the public transit line. The operator determines the transit fare and bus run frequency from period to period in order to maximize its operating profit. Moreover, we demonstrate the effectiveness of the two operation schemes for optimizing the system time cost and the operating profit by both theoretical analyses and numerical examples.
Epidemiological observations have demonstrated that ambient fine particulate matter with d
< 2.5 μm (PM
) as the major factor responsible for the increasing incidence of lung cancer in ...never-smokers. However, there are very limited experimental data to support the association of PM
with lung carcinogenesis and to compare PM
with smoking carcinogens.
To study whether PM
can contribute to lung tumorigenesis in a way similar to smoking carcinogen 4-methylnitrosamino-l-3-pyridyl-butanone (NNK) via 15-lipoxygenases (15-LOXs) reduction, normal lung epithelial cells and cancer cells were treated with NNK or PM
and then epigenetically and post-translationally examined the cellular and molecular profiles of the cells. The data were verified in lung cancer samples and a mouse lung tumor model.
We found that similar to smoking carcinogen NNK, PM2.5 significantly enhanced cell proliferation, migration and invasion, but reduced the levels of 15-lipoxygenases-1 (15-LOX1) and 15-lipoxygenases-2 (15-LOX2), both of which were also obviously decreased in lung cancer tissues. 15-LOX1/15-LOX2 overexpression inhibited the oncogenic cell functions induced by PM2.5/NNK. The tumor formation and growth were significantly higher/faster in mice implanted with PM2.5- or NNK-treated NCI-H23 cells, accompanied with a reduction of 15-LOX1/15-LOX2. Moreover, 15-LOX1 expression was epigenetically regulated at methylation level by PM2.5/NNK, while both 15-LOX1 and 15-LOX2 could be significantly inhibited by a set of PM2.5/NNK-mediated microRNAs.
Collectively, PM2.5 can function as the smoking carcinogen NNK to induce lung tumorigenesis by inhibiting 15-LOX1/15-LOX2.
Monolithic perovskite/silicon tandem solar cells show great promise for further efficiency enhancement for current silicon photovoltaic technology. In general, an interface (tunnelling or ...recombination) layer is usually required for electrical contact between the top and the bottom cells, which incurs higher fabrication costs and parasitic absorption. Most of the monolithic perovskite/Si tandem cells demonstrated use a hetero-junction silicon (Si) solar cell as the bottom cell, on small areas only. This work is the first to successfully integrate a low temperature processed (≤150 °C) planar CH 3 NH 3 PbI 3 perovskite solar cell on a homo-junction silicon solar cell to achieve a monolithic tandem without the use of an additional interface layer on large areas (4 and 16 cm 2 ). Solution processed SnO 2 has been effective in providing dual functions in the monolithic tandem, serving as an ETL for the perovskite cell and as a recombination contact with the n-type silicon homo-junction solar cell that has a boron doped p-type (p++) front emitter. The SnO 2 /p++ Si interface is characterised in this work and the dominant transport mechanism is simulated using Sentaurus technology computer-aided design (TCAD) modelling. The champion device on 4 cm 2 achieves a power conversion efficiency (PCE) of 21.0% under reverse-scanning with a V OC of 1.68 V, a J SC of 16.1 mA cm −2 and a high FF of 78% yielding a steady-state efficiency of 20.5%. As our monolithic tandem device does not rely on the SnO 2 for lateral conduction, which is managed by the p++ emitter, up scaling to large areas becomes relatively straightforward. On a large area of 16 cm 2 , a reverse scan PCE of 17.6% and a steady-state PCE of 17.1% are achieved. To our knowledge, these are the most efficient perovskite/homo-junction-silicon tandem solar cells that are larger than 1 cm 2 . Most importantly, our results demonstrate for the first time that monolithic perovskite/silicon tandem solar cells can be achieved with excellent performance without the need for an additional interface layer. This work is relevant to the commercialisation of efficient large-area perovskite/homo-junction silicon tandem solar cells.
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