SGS: Mutant Reduction for Higher-order Mutation-based Fault Localization

MBFL (Mutation-Based Fault Localization) is one of the most commonly studied fault localization techniques due to its promising fault localization effectiveness. However, MBFL incurs a high execution cost as it needs to execute the test suite on a large number of mutants. While previous studies have proposed mutant reduction methods for FOMs (First-Order Mutants) to help alleviate the cost of MBFL, the reduction of HOMs (Higher-Order Mutants) has not been thoroughly investigated. In this study, we propose SGS (Statement Granularity Sampling), a method which conducts HOMs reduction for HMBFL (Higher-Order Mutation-Based Fault Localization). Considering the relationship between HOMs and statements, we sample HOMs at the statement level to ensure each statement has corresponding HOMs. We empirically evaluate the fault localization effectiveness of HMBFL using SGS on 237 multiple-fault programs taken from the SIR and Codeflaws benchmarks. The experimental results show that (1) The best sampling ratio for HMBFL with SGS is 20%, which preserves the performance and reduces execution costs by 80% ; (2) The fault localization accuracy of HMBFL with SGS outperforms the state-of-the-art SBFL (Spectrum-Based Fault Localization) and MBFL techniques by 20%

Synthesis, biological evaluation and mechanism studies of C-23 modified 23-hydroxybetulinic acid derivatives as anticancer agents

A series of C-23 modified 23-hydroxybetulinic acid (HBA) derivatives were synthesized and evaluated for their antiproliferative activity against a panel of cancer cell lines (A2780, A375, B16, MCF-7 and HepG2). The biological screening results showed that most of the derivatives exhibited more potent antiproliferative activity than HBA, and compound 6e exhibited the most potent activity with IC50 values of 2.14 μM, 2.89 μM, and 3.97 μM against A2780, B16, and MCF-7 cells, respectively. Further anticancer mechanism studies revealed that compound 6e induced the generation of intracellular reactive oxygen species (ROS) and reduction of mitochondrial membrane potential (MMP) of B16 cells in a dose-dependent manner. Moreover, western blot analysis indicated that compound 6e downregulated the expression of anti-apoptotic protein Bcl-2 and upregulated the expression of proapoptotic protein Bax, activation of caspase 3 to induce cell apoptosis. Meanwhile, compound 6e significantly inhibited the phosphorylation of MEK, ERK, and Akt without affecting the expression of MEK, ERK, and Akt. Furthermore, the in vivo anti-tumor activity of 6e was validated (tumor inhibitory ratio of 68.4% at the dose of 30 mg/kg) in mice with B16 melanoma

Constructing Heterostructure through Bidentate Coordination toward Operationally Stable Inverted Perovskite Solar Cells

It has been reported that one of the influencing factors leading to stability issues in iodine-containing perovskite solar cells is the iodine loss from the perovskite layer. Herein, bidentate coordination is used with undercoordinated I− of the perovskite surface to construct the stable perovskite-based heterostructure. This strong halogen bonding effectively inhibits interfacial migration of I− into functional layers such as C60 and Ag. Moreover, passivation of the undercoordinated I− suppresses the release of I2 and further delays the formation of voids at the perovskite surface. The resulting inverted perovskite solar cell exhibits a power conversion efficiency of 22.59% and the unencapsulated device maintains 96.15% of its initial value after continuous operation for 500 h under illumination.journal articl

EXPLORING CHROMATIN REMODELING THROUGH CHEMICALLY ENGINEERED DESIGNER CHROMATIN

Brg/Brm Associated Factor (BAF) complexes are ATP-dependent chromatin remodelers that play an important role in governing genomic architecture and gene expression. These megadalton-sized molecular machines are found mutated in over 20% of human cancers. Therefore, understanding the mechanism of BAF-mediated remodeling holds promise for biomedical applications. In this thesis, we use chemically defined designer chromatins to decipher the mechanisms of BAF-mediated chromatin remodeling. First, using a DNA-barcoded nucleosome library containing various histone post-translational modifications (PTMs), mutations, and variants, we identified the chromatin features that affect the binding and remodeling activities of three BAF complexes. Importantly, we found that three BAF subfamilies, cBAF, PBAF, and ncBAF, have different preferences for different chromatin marks. Secondly, we investigated the role of nucleosome symmetry in chromatin remodeling activities. We developed an approach to synthesize asymmetric nucleosomes, which allows the orientation of a nucleosome to be tightly controlled relative to the underlying DNA sequence. Using this technology, we examined the functional consequence of asymmetry on BAF-mediated remodeling. Our results indicate that the asymmetric incorporation of cancer-associated histone mutations can reprogram the inherent activity of BAF chromatin remodeling to induce aberrant chromatin structure. Lastly, we introduced a FRET-based designer trinucleosome system to investigate a BAF-specific remodeling outcome, nucleosome eviction. Our current data suggest that BAF complex evicts histones from the nucleosome to which it is bound. We also found histone mutations at the nucleosome dimer-tetramer interface can specifically facilitate nucleosome eviction

Effect of current on biofilm-electrode reactor coupled with sulfur autotrophic denitrification process (BER-SAD) for nitrate removal from wastewater

The biofilm-electrode reactor coupled with sulfur autotrophic denitrification process (BER-SAD) was used to remove nitrate in groundwater, and the effect of current intensity on the denitrification characteristics of the coupled process was explored. Current intensity had a great influence on the denitrification effect of the coupled process, the maximum nitrate removal efficiency of 99.9% and lowest nitrite production were gained under the optimum current density of 100 mA. Moreover, the accumulation concentration of SO42- increased gradually with the increase of current intensity. With the increase of current intensity, the proportion of hydrogen autotrophic denitrification decreased, while the proportion of sulfur autotrophic denitrification increased

Tuning the Mechanical Properties of a DNA Hydrogel in Three Phases Based on ATP Aptamer

By integrating ATP aptamer into the linker DNA, a novel DNA hydrogel was designed, with mechanical properties that could be tuned into three phases. Based on the unique interaction between ATP and its aptamer, the mechanical strength of the hydrogel increased from 204 Pa to 380 Pa after adding ATP. Furthermore, with the addition of the complementary sequence to the ATP aptamer, the mechanical strength could be increased to 570 Pa