This article considers the flow shop problem of minimising the total weighted completion time in which the processing times of jobs are variable according to general position weighted learning ...effects. Two simple heuristics are proposed, and their worst-case error bounds are analysed. In addition, some complex heuristics (including simulated annealing algorithms) and a branch-and-bound algorithm are proposed as solutions to this problem. Finally, computational experiments are performed to examine the effectiveness and efficiency of the proposed algorithms.
One of the most common reactions of diazo compounds with alkenes is cyclopropanation, which occurs through metal carbene or free carbene intermediates. Alternative functionalization of alkenes with ...diazo compounds is limited, and a methodology for the addition of the elements of Z-CHR2 (with Z = H or heteroatom, and CHR2 originates from N2CR2) across a carbon–carbon double bond has not been reported. Here we report a novel reaction of diazo compounds utilizing a radical-mediated addition strategy to achieve difunctionalization of diverse alkenes. Diazo compounds are transformed to carbon radicals with a photocatalyst or an iron catalyst through PCET processes. The carbon radical selectively adds to diverse alkenes, delivering new carbon radical species, and then forms products through hydroalkylation by thiol-assisted hydrogen atom transfer (HAT), or forms azidoalkylation products through an iron catalytic cycle. These two processes are highly complementary, proceed under mild reaction conditions, and show high functional group tolerance. Furthermore, both transformations are successfully performed on a gram-scale, and diverse γ-amino esters, γ-amino alcohols, and complex spirolactams are easily prepared with commercially available reagents. Mechanistic studies reveal the plausible pathways that link the two processes and explain the unique advantages of each.
Entangled proteins have attracted significant research interest. Herein, we report the first rationally designed lasso proteins, or protein 1rotaxanes, by using a p53dim‐entwined dimer for ...intramolecular entanglement and a SpyTag‐SpyCatcher reaction for side‐chain ring closure. The lasso structures were confirmed by proteolytic digestion, mutation, NMR spectrometry, and controlled ligation. Their dynamic properties were probed by experiments such as end‐capping, proteolytic digestion, and heating/cooling. As a versatile topological intermediate, a lasso protein could be converted to a rotaxane, a heterocatenane, and a “slide‐ring” network. Being entirely genetically encoded, this robust and modular lasso‐protein motif is a valuable addition to the topological protein repertoire and a promising candidate for protein‐based biomaterials.
Artificially designed lasso proteins were modularly synthesized in cellulo based on assembly–reaction synergy. This enables the synthesis of protein (pseudo)rotaxanes, protein heterocatenanes, and protein‐based “slide‐ring” hydrogels via topological transformation.
The lysosomes of cancer cells have lower pH and higher viscosity than those of normal cells. These features can be used as sensitive and selective markers for cancer diagnosis. In this work, a pH and ...viscosity dual responsive lysosome targeting fluorescent probe 1 was designed based on the transformation of amino- and imino- forms of pyronine and the twisted intramolecular charge shuttle (TICS) sensing mechanism. Live cancer cells and tumors were effectively distinguished from normal cells and organs through fluorescence imaging of probe 1, which indicated that probe 1 could serve as an effective tool for visualization of tumors at organ level with high selectivity.
In this paper, we consider due-window assignment scheduling in the proportionate flow shop setting with position-dependent weights where the weights depend on the position in which a job is ...scheduled. Under the common due-window (CONW) and slack due-window (SLKW) assignment methods, the location of the window and its properties are established. The objective is to determine the sequence of all jobs to minimize the total weighted cost function where the total weighted cost function must also consider the window start time and size. Based on these considerations, the corresponding algorithm and algorithm complexity are proposed.
Aging is a biological process characterized by a progressive functional decline in tissues and organs, which eventually leads to mortality. Telomeres, the repetitive DNA repeat sequences at the end ...of linear eukaryotic chromosomes protecting chromosome ends from degradation and illegitimate recombination, play a crucial role in cell fate and aging. Due to the mechanism of replication, telomeres shorten as cells proliferate, which consequently contributes to cellular senescence and mitochondrial dysfunction. Cells are the basic unit of organismal structure and function, and mitochondria are the powerhouse and metabolic center of cells. Therefore, cellular senescence and mitochondrial dysfunction would result in tissue or organ degeneration and dysfunction followed by somatic aging through multiple pathways. In this review, we summarized the main mechanisms of cellular senescence, mitochondrial malfunction and aging triggered by telomere attrition. Understanding the molecular mechanisms involved in the aging process may elicit new strategies for improving health and extending lifespan.
Carbon dots (CDs) have a wide range of applications in chemical, physical and biomedical research fields. We are particularly interested in the use of CDs as fluorescence nanomaterials for targeted ...tumor cell imaging. One of the important aspects of success is to enhance the fluorescence quantum yields (QY) of CDs as well as increase their targetability to tumor cells. However, most of the reported CDs are limited by relative low QY. In the current study, for the first time, one-step synthesis of highly luminescent CDs by using folic acid (FA) as single precursor was obtained in natural water through hydrothermal method. The as-prepared CDs exhibited QY as high as 94.5% in water, which is even higher than most of organic fluorescent dyes. The obtained CDs showed excellent photoluminescent activity, high photostability and favorable biocompatibility. The FA residuals in CDs led to extraordinary targetability to cancer cells and promoted folate receptor-mediated cellular uptake successfully, which holds a great potential in biological and bioimaging studies.
Concentration scaling on linear viscoelastic properties of cellular suspensions has been studied by rheometric characterisation of
suspensions and human blood in a wide range of volume fraction under ...small amplitude oscillatory shear experiments. The rheometric characterisation results are analysed by the time-concentration superposition (TCS) principle and show a power law scaling of characteristic relaxation time, plateau modulus and the zero-shear viscosity over the concentration ranges studied. The results show that the concentration effect of
suspensions on their elasticity is much stronger than that of human blood due to its strong cellular interactions and a high aspect ratio. For human blood, no obvious phase transition could be observed over the range of hematocrits studied here and with respect to a high-frequency dynamic regime, only one concentration scaling exponent could be identified. For
suspensions with respect to a low-frequency dynamic regime, three concentration scaling exponents in the volume fraction Region I (0.36≤ϕ/ϕref≤0.46), Region II (0.59≤ϕ/ϕref≤2.89) and Region III (3.11≤ϕ/ϕref≤3.44) are identified. The image observation shows that the network formation of
suspensions occurs as the volume fraction is increased from Region I to Region II; the sol-gel transition takes place from Region II to Region III. In combination with analysis of other nanoscale suspensions and liquid crystalline polymer solutions reported in the literature, it is revealed that such a power law concentration scaling exponent depends on colloidal or molecular interactions mediated with solvent and is sensitive to the equilibrium phase behaviour of complex fluids. The TCS principle is an unambiguous tool to give a quantitative estimation.
Granular materials, composed of densely packed particles, are known to possess unique mechanical properties that are highly dependent on the surface structure of the particles. A microscopic ...understanding of the structure‐property relationship in these systems remains unclear. Here, supra‐nanoparticle clusters (SNPCs) with precise structures are developed as model systems to elucidate the unexpected elastic behaviors. SNPCs are prepared by coordination‐driven assembly of polyhedral oligomeric silsesquioxane (POSS) with metal‐organic polyhedron (MOP). Due to the disparity in sizes, the POSS‐MOP assemblies, like their classic nanoparticles counterparts, ordering is suppressed, and the POSS‐MOP mixtures will vitrify or jam as a function of decreasing temperature. An unexpected elasticity is observed for the SNPC assemblies with a high modulus that is maintained at temperatures far beyond the glass transition temperature. From studies on the dynamics of the hierarchical structures of SNPCs and molecular dynamic simulation, the elasticity has its origins in the interpenetration of POSS‐ended arms. The physical molecular interpenetration and inter‐locking phenomenon favors the convenient solution or pressing processing of the novel cluster‐based elastomers.
Supra‐nanoparticle clusters (SNPCs) were synthesized by convergence of metal–organic polyhedron scaffolds with precise giant building blocks. The mechanical properties and structural dynamics can be regulated by fine‐tuning the surface functionalization of the terminal POSS moieties. Unexpected elasticity with high Young's modulus of the OPOSS‐ended SNPCs was found to be highly correlated with the interpenetration of the neighboring GLs.
Nowadays there is a continuously increasing worldwide concern for the development of wastewater treatment technologies. The utilization of iron oxide nanomaterials has received much attention due to ...their unique properties, such as extremely small size, high surface-area-to-volume ratio, surface modifiability, excellent magnetic properties and great biocompatibility. A range of environmental clean-up technologies have been proposed in wastewater treatment which applied iron oxide nanomaterials as nanosorbents and photocatalysts. Moreover, iron oxide based immobilization technology for enhanced removal efficiency tends to be an innovative research point. This review outlined the latest applications of iron oxide nanomaterials in wastewater treatment, and gaps which limited their large-scale field applications. The outlook for potential applications and further challenges, as well as the likely fate of nanomaterials discharged to the environment were discussed.
► The review outlined latest applications of iron oxide nonmaterials in wastewater treatment. ► The outlook for potential applications and further challenges was also provided. ► The likely fate of the nanomaterials discharged to the environment was addressed.
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