Improvements to enhance robustness of third-order scale-independent WENO-Z schemes

Although there are many improvements to WENO3-Z that target the achievement of optimal order in the occurrence of the first-order critical point (CP1), they mainly address resolution performance, while the robustness of schemes is of less concern and lacks understanding accordingly. In light of our analysis considering the occurrence of critical points within grid intervals, we theoretically prove that it is impossible for a scale-independent scheme that has the stencil of WENO3-Z to fulfill the above order achievement, and current scale-dependent improvements barely fulfill the job when CP1 occurs at the middle of the grid cell. In order to achieve scale-independent improvements, we devise new smoothness indicators that increase the error order from 2 to 4 when CP1 occurs and perform more stably. Meanwhile, we construct a new global smoothness indicator that increases the error order from 4 to 5 similarly, through which new nonlinear weights with regard to WENO3-Z are derived and new scale-independents improvements, namely WENO-ZES2 and -ZES3, are acquired. Through 1D scalar and Euler tests, as well as 2D computations, in comparison with typical scale-dependent improvement, the following performances of the proposed schemes are demonstrated: The schemes can achieve third-order accuracy at CP1 no matter its location in the stencil, indicate high resolution in resolving flow subtleties, and manifest strong robustness in hypersonic simulations (e.g., the accomplishment of computations on hypersonic half-cylinder flow with Mach numbers reaching 16 and 19, respectively, as well as essentially non-oscillatory solutions of inviscid sharp double cone flow at M=9.59), which contrasts the comparative WENO3-Z improvement

Synthetic Chemotaxis: Path Tracking Vesicles with DNA Walkers

Here we demonstrate dynamic synthetic vesicles (SVs) capable of chasing one another on two dimensional (2D) surfaces by programming DNA components.1 As a programmable material, DNA has been engineered for generating synthetic molecular systems such as nanostructures, affinity reagents, motors, and logic gates. We show that directed motility in DNA functionalized SVs can be achieved by combining toehold switchable oligonucleotides with signaling strands and that the ‘follow’ vesicle recognizes the path that the ‘lead’ vesicle has travelled and tracks the trajectory with enhanced speed. To demonstrate such synthetic chemotaxis, we first self-assembled vesicles using phospholipid-oligonucleotide conjugates whose sequence contains our motility designs. The vesicle has an average diameter of ~200 nm and decorated with multiple DNA walkers such that it can migrate on an RNA fuel decorated glass coverslip. Paper presented virtually for 17th Annual Conference on Foundations of Nanoscience: Self-Assembled Architectures and Devices (FNANO20)

Mechanistic Understanding of Surface Migration Dynamics with DNA Walkers

Dynamic DNA walkers can move cargoes on a surface through various mechanisms including enzymatic reactions and strand displacement. While they have demonstrated high processivity and speed, their motion dynamics are not well understood. Here, we utilize an enzyme-powered DNA walker as a model system and adopt a random walk model to provide new insight on migration dynamics. Four distinct migration modes (ballistic, Lévy, self-avoiding, and diffusive motions) are identified. Each mode shows unique step time and velocity distributions which are related to mean squared displacement (MSD) scaling. Experimental results are in excellent agreement with the theoretical predictions. With a better understanding of the dynamics, we performed a mechanistic study, elucidating the effects of cargo types and sizes, walker sequence designs, and environmental conditions. Finally, this study provides a set of design principles for tuning the behaviors of DNA walkers. The DNA walkers from this work could serve as a versatile platform for mathematical studies and open new opportunities for bioengineering.</p

Gold(I)-Catalyzed Intra- and Intermolecular Alkenylations of beta-Yne-pyrroles: Facile Formation of Fused Cycloheptapyrroles and Functionalized Pyrroles

An efficient gold(I)-catalyzed alkenylation of beta-alkyne-substituted pyrroles is reported. The intramolecular reaction gives straightforward access to different types of seven-membered-ring-fused pyrroles with endo-selectivity, and the intermolecular reaction with alkynes provides functionalized pyrrole derivatives

The Culprit behind the Mass Death of Mangroves: Egrets or <i>Rats</i> (<i>Rattus losea</i>)?

Mangroves play a crucial role in maintaining coastal ecological balance. This study focused on the impact of branch-breaking behavior on the mortality of Rhizophora stylosa in the Guangxi Shankou Mangrove Reserve. However, we found mangrove mortality in areas devoid of egret habitation, prompting a reevaluation of our research hypothesis. Further investigation suggested that nesting behavior was the primary cause of mangrove mortality. A comparison of the data from areas with egrets (Egretta garzetta, Ardea intermedia) and lesser rice-field rats (Rattus losea) activity indicated significant mechanical damage caused by rats to mangroves as the main cause of mortality. Additionally, we found that the biological characteristics of R. stylosa, particularly its stunted growth and recovery abilities after branch breaking, were key factors affecting its survival. These findings imply that rat-induced mortality may not occur in other less susceptible mangrove species. The results contradict assumptions regarding the impact of egret behavior and highlight the importance of the biological characteristics of R. stylosa. This offers fresh insights into mangrove conservation and management, emphasizing the need for ongoing observation and hypotheses verification. Future studies should explore the influence of lesser rice-field rats’ activity and the intrinsic characteristics of R. stylosa on the ecosystem’s long-term stability

Tunable Dual-Wavelength with Twin-Pulse Dissipative Solitons in All-Normal Dispersion Yb-Doped Fiber Laser

A tunable dual-wavelength with two separated twin-pulse dissipative solitons (DSs) of Yb-doped mode-locked fiber laser in the all-normal-dispersion (ANDi) regime is firstly reported and demonstrated in this paper. A Sagnac loop is used as an all-fiber format spectral filter in the laser cavity, and stable twin-pulse DSs with different wavelength mode-locked lasers are achieved by the nonlinear polarization evolution (NPE) effect. By adjusting the polarization state of the Sagnac loop, the spectral ranges of the dual-wavelength can be tuned from 1031.3 nm to 1041.5 nm and from 1067.1 nm to 1080.9 nm, respectively. However, the pulse space between the two separated twin-pulse DSs is maintained, i.e., 41.63 ns. Furthermore, the twin-pulse can regress to the single-pulse when the pump power keeps dropping. It has been observed that the highest energy of the two twin-pulse DSs output is 23.36 nJ at a repetition rate of 2.282 MHz with a maximum pump power of 560 mW

Gold(I)-Catalyzed Intra- and Intermolecular Alkenylations of β‑Yne-pyrroles: Facile Formation of Fused Cycloheptapyrroles and Functionalized Pyrroles

An efficient gold­(I)-catalyzed alkenylation of β-alkyne-substituted pyrroles is reported. The intramolecular reaction gives straightforward access to different types of seven-membered-ring-fused pyrroles with <i>endo</i>-selectivity, and the intermolecular reaction with alkynes provides functionalized pyrrole derivatives