Tabu search for generalized minimum spanning tree problem

The Generalized Minimum Spanning Tree (GMST) problem requires spanning exactly one node from every cluster in an undirected graph. GMST problems are encountered in telecommunications network planning. A Tabu Search (TS) for the GMST problem is presented in this article. In our computational tests on 194 TSPLIB instances, TS found 152 optimal solutions. For those 42 unsolved instances, our algorithm has improved some previously best known solutions. Lower bounds of some unknown problems are improved by our heuristic relaxation algorithm

Microbial Defluorination of Unsaturated Per- and Polyfluorinated Carboxylic Acids under Anaerobic and Aerobic Conditions: A Structure Specificity Study.

The recently discovered microbial reductive defluorination of two C6 branched and unsaturated fluorinated carboxylic acids (FCAs) provided valuable insights into the environmental fate of per- and polyfluoroalkyl substances (PFASs) and potential bioremediation strategies. However, a systematic investigation is needed to further demonstrate the role of C═C double bonds in the biodegradability of unsaturated PFASs. Here, we examined the structure-biodegradability relationships of 13 FCAs, including nine commercially available unsaturated FCAs and four structurally similar saturated ones, in an anaerobic defluorinating enrichment and an activated sludge community. The anaerobic and aerobic transformation/defluorination pathways were elucidated. The results showed that under anaerobic conditions, the α,β-unsaturation is crucial for FCA biotransformation via reductive defluorination and/or hydrogenation pathways. With sp2 C-F bonds being substituted by C-H bonds, the reductive defluorination became less favorable than hydrogenation. Moreover, for the first time, we reported enhanced degradability and defluorination capability of specific unsaturated FCA structures with trifluoromethyl (-CF3) branches at the α/β-carbon. Such FCA structures can undergo anaerobic abiotic defluorination in the presence of reducing agents and significant aerobic microbial defluorination. Given the diverse applications and emerging concerns of fluorochemicals, this work not only advances the fundamental understanding of the fate of unsaturated PFASs in natural and engineered environments but also may provide insights into the design of readily degradable fluorinated alternatives to existing PFAS compounds

Protective Functions of Liver X Receptor α in Established Vulnerable Plaques: Involvement of Regulating Endoplasmic Reticulum–Mediated Macrophage Apoptosis and Efferocytosis

Background Liver X receptor (LXR) belongs to the metabolic nuclear receptor superfamily, which plays a critical regulatory role in vascular physiology/pathology. However, effects of systemic LXR activation on established vulnerable plaques and the potential isotype‐specific role involved remain unclear. Methods and Results The 8‐week‐old male apolipoprotein E−/− mice went through carotid branch ligation and renal artery constriction, combined with a high‐fat diet. Plaques in the left carotid artery acquired vulnerable features 4 weeks later, confirmed by magnetic resonance imaging scans and histological analysis. From that time on, mice were injected intraperitoneally daily with PBS or GW3965 (10 mg/kg per day) for an additional 4 weeks. Treatment with LXR agonists reduced the lesion volume by 52.61%, compared with the vehicle group. More important, a profile of less intraplaque hemorrhage detection and necrotic core formation was found. These actions collectively attenuated the incidence of plaque rupture. Mechanistically, reduced lesional apoptosis, enhanced efferocytosis, and alleviated endoplasmic reticulum stress are involved in the process. Furthermore, genetic ablation of LXRα, but not LXRβ, blunted the protective effects of LXR on the endoplasmic reticulum stress–elicited C/EBP‐homologous protein pathway in peritoneal macrophages. In concert with the LXRα‐predominant role in vitro, activated LXR failed to stabilize vulnerable plaques and correct the acquired cellular anomalies in LXRα−/− apolipoprotein E−/− mice. Conclusions Our results revealed that LXRα mediates the capacity of LXR activation to stabilize vulnerable plaques and prevent plaque rupture via amelioration of macrophage endoplasmic reticulum stress, lesional apoptosis, and defective efferocytosis. These findings might expand the application scenarios of LXR therapeutics for atherosclerosis

Total Synthesis of (+)–Haperforin G

(+)-Haperforin G was synthesized in 20 steps from commercially available starting materials. A Co-catalyzed intramolecular Pauson–Khand reaction was used for stereoselective construction of cyclopentanone bearing an all-carbon quaternary stereogenic center at the bridge-head position. Light-initiated photocatalysis was used for convergent and asymmetric cross-coupling of the unstabilized C(sp3) radical with an enone. The developed chemistry paves the way to the synthesis of structurally diverse analogs of haperforin G (6)

InDels Identification and Association Analysis with Spike and Awn Length in Chinese Wheat Mini-Core Collection

Diversity surveys of germplasm are important for gaining insight into the genomic basis for crop improvement; especially InDels, which are poorly understood in hexaploid common wheat. Here, we describe a map of 89,923 InDels from exome sequencing of 262 accessions of a Chinese wheat mini-core collection. Population structure analysis, principal component analysis and selective sweep analysis between landraces and cultivars were performed. Further genome-wide association study (GWAS) identified five QTL (Quantitative Trait Loci) that were associated with spike length, two of them, on chromosomes 2B and 6A, were detected in 10 phenotypic data sets. Assisted with RNA-seq data, we identified 14 and 21 genes, respectively that expressed in spike and rachis within the two QTL regions that can be further investigated for candidate genes discovery. Moreover, InDels were found to be associated with awn length on chromosomes 5A, 6B and 4A, which overlapped with previously reported genetic loci B1 (Tipped 1), B2 (Tipped 2) and Hd (Hooded). One of the genes TaAGL6 that was previously shown to affect floral organ development was found at the B2 locus to affect awn length development. Our study shows that trait-associated InDels may contribute to wheat improvement and may be valuable molecular markers for future wheat breedin

Dipolar cations confer defect tolerance in wide-bandgap metal halide perovskites

Efficient wide-bandgap perovskite solar cells (PSCs) enable high-efficiency tandem photovoltaics when combined with crystalline silicon and other low-bandgap absorbers. However, wide-bandgap PSCs today exhibit performance far inferior to that of sub-1.6-eV bandgap PSCs due to their tendency to form a high density of deep traps. Here, we show that healing the deep traps in wide-bandgap perovskites-in effect, increasing the defect tolerance via cation engineering-enables further performance improvements in PSCs. We achieve a stabilized power conversion efficiency of 20.7% for 1.65-eV bandgap PSCs by incorporating dipolar cations, with a high open-circuit voltage of 1.22 V and a fill factor exceeding 80%. We also obtain a stabilized efficiency of 19.1% for 1.74-eV bandgap PSCs with a high open-circuit voltage of 1.25 V. From density functional theory calculations, we find that the presence and reorientation of the dipolar cation in mixed cation-halide perovskites heals the defects that introduce deep trap states.status: publishe