A 3-D open-framework material with intrinsic chiral topology used as a stationary phase in gas chromatography.

Compared with liquid chromatography and capillary electrophoresis, the diversity of gas chromatography chiral stationary phases is rather limited. Here, we report the fabrication of Co(D-Cam)1/2(bdc)1/2(tmdpy) (D-Cam = D-camphoric acid; bdc = 1,4-benzenedicarboxylate; tmdpy = 4,4'-trimethylenedipyridine)-coated open tubular columns for high-resolution gas chromatographic separation of compounds. The Co(D-Cam)1/2(bdc)1/2(tmdpy) compound possesses a 3-D framework containing enantiopure building blocks embedded in intrinsically chiral topological nets. In this study, two fused-silica open tubular columns with different inner diameters and lengths, including column A (30 m × 530 µm i.d.) and column B (2 m × 75 µm i.d.), were prepared by a dynamic coating method using Co-(D-Cam)1/2(bdc)1/2(tmdpy) as the stationary phase. The chromatographic properties of the two columns were investigated using n-dodecane as the test compound at 120 °C. The number of theoretical plates (plates/m) of the two metal-organic framework columns was 1,450 and 3,100, respectively. The separation properties were evaluated using racemates, isomers, alkanes, alcohols, and Grob's test mixture. The limit of detection and limit of quantification were found to be 0.125 and 0.417 ng for citronellal enantiomers, respectively. Repeatability (n = 6) showed lower than 0.25 % relative standard deviation (RSD) for retention times and lower than 2.2 % RSD for corrected peak areas. The experimental results showed that the stationary phase has excellent selectivity and also possesses good recognition ability toward these organic compounds, especially chiral compounds.

Stable seasonal migration patterns in giant pandas.

A critical function of animal movement is to maximize access to essential resources in temporally fluctuating and spatially heterogeneous environments. Seasonally mediated resource fluctuations may influence animal movements, enabling them to track changing resource distributions, resulting in annual migration patterns. The conservation-dependent giant panda ( Ailuropoda melanoleuca) displays seasonal movement patterns; however, the key factor driving these seasonal migration patterns remains poorly understood. Here, we used GPS tracking collars to monitor the movements of six giant pandas over a 12-year period across different elevations, and performed statistical analysis of seasonal migration directions, routes, habitat revisitation, home range overlap, first arrival events, and stability. Our results revealed a compelling pattern of seasonal migrations that facilitated the ability of the pandas to forage at the appropriate time and place to maximize nutritional intake. Our results indicated that pandas utilize spatial memory to locate reliable food resources, as evidenced by their annual return to the same or similar winter and summer home ranges and the consistently maintained percentage of home range overlap. These novel insights into giant panda foraging and movement ecology not only enhance our understanding of its ability to adapt to nutritionally poor dietary resources but also provide important information for the development of resource utilization-based protection and management strategies.

Recommendation of SLM Process Parameters Based on Analytic Hierarchy Process and Weighted Particle Swarm Optimization for High-Temperature Alloys.

Selective laser melting (SLM) of high-temperature alloys involves intricate interdependencies among key process parameters, such as laser power and scanning speed, affecting properties such as density and tensile strength. However, relying solely on experiential knowledge for process parameter design often hampers the precise attainment of target requirements. To address this challenge, we propose an innovative approach that integrates the analytic hierarchy process (AHP) and weighted particle swarm optimization (WPSO) to recommend SLM process parameters for high-temperature alloy fabrication. Our proposed AHP-WPSO model consists of three main steps. First, a comprehensive historical database is established, capturing the process parameters and performance metrics of high-temperature alloy SLM parts. Utilizing an AHP framework, we compute the performance similarity between target and historical cases, applying rational thresholds to identify analogous cases. When suitable analogs are elusive, the model seamlessly transitions to the second step. Here, the WPSO model optimizes and recommends process parameters according to target specifications. Lastly, our experimental validation of the GH4169 high-temperature alloy through SLM experiments corroborates the effectiveness of our AHP-WPSO model in making process parameter recommendations. The outcomes underscore the model's high accuracy, attaining a recommendation precision of 99.81% and 96.32% when historical analogs are present and absent, respectively. This innovative approach offers a robust and reliable solution to the challenges posed in SLM process parameter optimization for high-temperature alloy applications.

Chiral metal-organic frameworks for high-resolution gas chromatographic separations.

Chiral metal-organic framework coated open tubular columns are used in the high-resolution gas chromatographic separation of chiral compounds. The columns have excellent selectivity and also possess good recognition ability toward a wide range of organic compounds such as alkanes, alcohols, and isomers.

List-Based Simulated Annealing Algorithm for Traveling Salesman Problem.

Simulated annealing (SA) algorithm is a popular intelligent optimization algorithm which has been successfully applied in many fields. Parameters' setting is a key factor for its performance, but it is also a tedious work. To simplify parameters setting, we present a list-based simulated annealing (LBSA) algorithm to solve traveling salesman problem (TSP). LBSA algorithm uses a novel list-based cooling schedule to control the decrease of temperature. Specifically, a list of temperatures is created first, and then the maximum temperature in list is used by Metropolis acceptance criterion to decide whether to accept a candidate solution. The temperature list is adapted iteratively according to the topology of the solution space of the problem. The effectiveness and the parameter sensitivity of the list-based cooling schedule are illustrated through benchmark TSP problems. The LBSA algorithm, whose performance is robust on a wide range of parameter values, shows competitive performance compared with some other state-of-the-art algorithms.

Inlay of Bi2O2CO3 nanoparticles onto Bi2WO6 nanosheets to build heterostructured photocatalysts.

Surface-dispersive-type Bi2O2CO3/Bi2WO6 heterostructured nanosheets were successfully prepared via anion exchange in a hydrothermal process with the graphitic carbon nitride (g-C3N4) as a precursor of CO3(2-). The Bi2O2CO3 nanoparticles (with diameters about 5 nm) were highly homogeneously dispersed and inlaid in the single-crystalline Bi2WO6 nanosheets. The composites with intimate interfacial contacts between Bi2O2CO3 and Bi2WO6 exhibited superior visible light photocatalytic activity towards the degradation of rhodamine B (RhB). The composite nanosheets containing 7.86 wt% Bi2O2CO3 showed the best performance and the degradation rate of RhB was 6 times faster than that with the bare Bi2WO6. The dramatic enhancement of the photocatalytic activity of the Bi2O2CO3/Bi2WO6 photocatalysts can be attributed to the hetero-interfaces between Bi2O2CO3 and Bi2WO6, their intrinsically layered structure, two-dimensional morphology and the effective separation of the photoinduced carriers at the interfaces and in the semiconductors. This method can be used to design and prepare other Aurivillius heterostructured semiconductors for efficient light harvesting and energy conversion applications.

Isolation and characterization of 14 microsatellite loci for the Chevrier's field mouse (Apodemus chevrieri).

We describe the isolation and characterization of 14 microsatellite loci in the Chevrier's field mouse from genomic DNA-enriched libraries. The 14 loci were highly polymorphic with numbers of alleles per locus in 24 individuals ranging from three to 13, observed heterozygosity from 0.381 to 0.867 and expected heterozygosity from 0.448 to 0.931. All loci followed Hardy-Weinberg expectations except for CFM3, CFM10 and CFM12 loci. No significant linkage association was found among all these loci. The 14 polymorphic microsatellite loci will be useful in studying phylogeography and population genetics of the Chevrier's field mouse.