Microwave assisted synthesis and antimicrobial activity of Fe3O4-doped ZrO2 nanoparticles

Composites play important role in dental filling by controlling shrinkage along with correction in teeth's shape and position. Rehabilitation of severely worn dentition can be achieved using mechanically strong composites. This study aims to synthesize zirconia-based composites to be used as dental fillers. Effect of microwave powers (100–900?W) along with Fe₃O₄ doping are studied on the structural, mechanical and magnetic properties of stabilized zirconia. SEM and TEM reveal formation of spherical nanoparticles with diameter of ～30?nm. XRD results shows phase pure tetragonal zirconia (t-ZrO₂) at microwave power of 500?W without any post heat treatment. Crystallite size calculated from XRD data (～23?nm) matches well with the previously reported value for stabilization of t-ZrO₂. Microwave energy dissipation results in stresses causing volume shrinkage leading to monoclinic to tetragonal phase transformation with higher X-ray density and hardness of ～1347HV. VSM results show ferromagnetic response with low coercivity (600Oe) value and saturation magnetization (～2emu/g). It is worth mentioning here that this is one of its kind study reporting synthesis of room temperature stabilized Fe₃O₄ doped zirconia composites at microwave power of 500?W. Antibacterial studies reveal inhibition zone of ～32?mm against bacillus bacteria suggesting their potential use as dental filler.     

Common due date assignment scheduling for a no-wait flowshop with convex resource allocation and learning effect

This article addresses the no-wait flowshop scheduling problem with simultaneous consideration of common due date assignment, convex resource allocation and learning effect in a two machine setting. The processing time of each job can be controlled by its position in a sequence and also by allocating extra resource, which is a convex function of the amount of a common continuously divisible resource allocated to the job. The objective is to determine the optimal common due date, the resource allocation and the schedule of jobs such that the total earliness, tardiness and common due date cost (the total resource consumption cost) are minimized under the constraint condition that the total resource consumption cost (the total earliness, tardiness and common due date cost) is limited. Polynomial time algorithms are developed for two versions of the problem.     

Dhh1 is a member of the SESA network

The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (S my2, E ap1, S cp160, A sc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA.     

Pseudouridine synthase 7 impacts Candida albicans rRNA processing and morphological plasticity

RNA can be modified in over 100 distinct ways, and these modifications are critical for function. Pseudouridine synthases catalyse pseudouridylation, one of the most prevalent RNA modifications. Pseudouridine synthase 7 modifies a variety of substrates in Saccharomyces cerevisiae including tRNA, rRNA, snRNA, and mRNA, but the substrates for other budding yeast Pus7 homologues are not known. We used CRISPR-mediated genome editing to disrupt Candida albicans PUS7 and find absence leads to defects in rRNA processing and a decrease in cell surface hydrophobicity. Furthermore, C. albicans Pus7 absence causes temperature sensitivity, defects in filamentation, altered sensitivity to antifungal drugs, and decreased virulence in a wax moth model. In addition, we find C. albicans Pus7 modifies tRNA residues, but does not modify a number of other S. cerevisiae Pus7 substrates. Our data suggests C. albicans Pus7 is important for fungal vigour and may play distinct biological roles than those ascribed to S. cerevisiae Pus7.     

New environmental-friendly yellow pigments Y_(4-x)A_xMoO_(9+δ)(A =Ta,Tb)

A series of inorganic yellow pigments with general formula Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb), where x = 0,0.05,0.1,0.2, 0.4 for Ta and χ = 0, 0.005, 0.01.0.03, 0.05 for Tb,were synthesized by a conventional ceramic method at 1400 ℃ for 6 h in air. The samples were characterized by XRD,EDS,XPS,SEM,TG-DSC,UV-vis-NIR reflectance spectroscopy and CIE L*a*b* color scales. It is found that the substitution of A(A = Ta, Tb) for Y~(3+) in Y_4 MoO_9 decreases the NIR reflectance of the pigment samples, but the developed pigments Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb) still exhibit impressive NIR solar reflectance. The brighter yellow color of inorganic pigments Y_(4-x)A_xMoO_(9+δ)(A = Ta, Tb) is available when x is about 0.1 for Ta and 0.01 for Tb. The results make them a series of potential candidates as ecological yellow pigments because of their high reflectance, lightness, intense coloration and excellent thermal and chemical stability.     

不同种源地香叶树籽的油脂含量及脂肪酸组成分析

为探明不同种源地香叶树作为油料树种的开发价值，采集了全国6省20县市的香叶树果实，对香叶树全果、果肉及籽的油脂含量及脂肪酸组成进行了分析，并采用ward法对不同种源地香叶树籽油脂肪酸进行了聚类分析。结果表明：香叶树全果、果肉以及籽的平均油脂含量分别为43.31%、42.38%及46.12%；全果油脂肪酸组成以月桂酸、油酸和癸酸为主；果肉油以油酸和棕榈酸为主；而籽油则以月桂酸和癸酸为主，月桂酸含量为53.20%~70.30%，月桂酸和癸酸总含量达76.40%~90.10%；聚类分析将不同种源地香叶树分为3大类，云南省、贵州省及广西省的香叶树属低月桂酸类型，福建省、江西省及湖南省的香叶树属中高月桂酸型。香叶树可作为生产中碳链脂肪酸的新晋树种，福建省的香叶树籽油脂含量高，且籽油中月桂酸含量高，作为中碳链脂肪酸的原料地具有明显的开发优势。     

Preliminary Structural Data Revealed That the SARS-CoV-2 B.1.617 Variant's RBD Binds to ACE2 Receptor Stronger Than the Wild Type to Enhance the Infectivity

The evolution of new SARS-CoV-2 variants around the globe has made the COVID-19 pandemic more worrisome, further pressuring the health care system and immunity. Novel variations that are unique to the receptor-binding motif (RBM) of the receptor-binding domain (RBD) spike glycoprotein, i. e. L452R-E484Q, may play a different role in the B.1.617 (also known as G/452R.V3) variant's pathogenicity and better survival compared to the wild type. Therefore, a thorough analysis is needed to understand the impact of these mutations on binding with host receptor (RBD) and to guide new therapeutics development. In this study, we used structural and biomolecular simulation techniques to explore the impact of specific mutations (L452R-E484Q) in the B.1.617 variant on the binding of RBD to the host receptor ACE2. Our analysis revealed that the B.1.617 variant possesses different dynamic behaviours by altering dynamic-stability, residual flexibility and structural compactness. Moreover, the new variant had altered the bonding network and structural-dynamics properties significantly. MM/GBSA technique was used, which further established the binding differences between the wild type and B.1.617 variant. In conclusion, this study provides a strong impetus to develop novel drugs against the new SARS-CoV-2 variants.     

Synthesis,Anticancer Activity,Structure-Activity Relationship and Mechanistic Investigations of Falcarindiol Analogues

Forty samples of optically active falcarindiol analogues are synthesized by using the easily available C2 symmetric (R)- and (S)-1,1’-binaphth-2-ol (BINOL) in combination with Ti(OⁱPr)₄, Zn powder and EtI. Their anticancer activities on Hccc-9810, HepG2, MDA-MB-231, Hela, MG-63 and H460 cells are assayed to elucidate their structure-activity relationships. These results showed that the falcarindiol analogue (3R,8S)- 2 i with the terminal double bond has the most potent anti-proliferation effect on Hccc-9810 cells with IC₅₀ value of 0.46 μM. The falcarindiol analogue (3R,8S)- 2 i can induce obvious Hccc-9810 cell apoptosis in a concentration-dependent manner by Hoechst staining and flow cytometry analysis. The proposed mechanism suggests that the falcarindiol analogue (3R,8S)- 2 i increases LDH release and MDA content, and reduces the levels of SOD activity, which lead to the accumulation of oxidative stress and induce apoptosis in Hccc-9810 cells.     

The periodic system and the idea of a chemical element: From Mendeleev to superheavy elements

Like other scientific concepts, the idea of a chemical element has changed considerably over time, since it was first established in the Enlightenment era. In Dmitri Mendeleev's construction of the periodic system, he distinguished between simple substances and elements as defined by their atomic weights. The foundation of the periodic system on the latter concept led to several challenges. For example, the system seemed unable to accommodate the radioactive substances eventually recognised as isotopes. Around 1920, elements were consequently redefined in terms of their atomic numbers, a nuclear property that could be determined by X‐ray spectroscopy. Although this understanding of an element has stood the test of time, new questions turned up relating to the concept of an element following the syntheses of transuranic elements since the early 1940s. These syntheses of very heavy elements have additionally led chemists and physicists to reconsider the criteria for the discovery of a new element. Recently, elements have been officially recognised on the sole ground that a small number of very heavy atomic nuclei were identified. The paper discusses how the notion of an element was modified during different periods of time, the reasons for the modifications, and the values ascribed to them in the communities of chemists and physicists.