Search

Cell division is a necessity of life which can be either mitotic or amitotic. While both are fundamental, amitosis is sometimes considered a relic of little importance in biology. Nevertheless, eukaryotes often have polyploid cells, including cancer cells, which may divide amitotically. To understand how amitosis ensures the completion of cell division, we turn to the macronuclei of ciliates. The grand scheme governing the proliferation of the macronuclei of ciliate cells, which involves chromosomal replication and amitosis, is currently unknown, which is crucial for developing population genetics model of ciliate populations. Using a novel model that encompasses a wide range of mechanisms together with experimental data of the composition of mating types at different stages derived from a single karyonide of Tetrahymena thermophila, we show that the chromosomal replication of the macronucleus has a strong head-start effect, with only about five copies of chromosomes replicated at a time and persistent reuse of the chromosomes involved in the early replication. Furthermore the fission of a fully grown macronucleus is non-random with regard to chromosome composition, with a strong tendency to push chromosomes and their replications to the same daughter cell.

The Es4 source rock is the primary source of hydrocarbon in deep reservoirs in the Baxian Sag, Jizhong Depression of Bohai Bay Basin, China, and its quantitative description is useful for understanding hydrocarbon generation and accumulation in the deep basin. The Es4 source rock contains organofacies C, D/E and F, with organofacies C having a thin thickness of less than 40 m and organofacies D/E having a thickness of 50 m and 250 m. The drilled Es4 source rock has a maximum RO of 1.27%, indicating that it is in the late oil window. The kinetic parameters for three organofacies source rock have been obtained from the simulation of gold tube pyrolysis. The result showed that organofacies C, D/E and F source rock entered into the mature level in sequence, but that at 150 °C, the organofacies C will be transformed to around 90% of their original state. For organofacies D/E and F, the hydrocarbon generation potential is still high, with condensate and wet gas dominating.

Most of inchworm piezoelectric actuators suffer from complicated structures and control systems due to the utilization of three or more piezoelectric stacks. Various approaches have been further developed to reduce the piezoelectric stacks. However, output characteristics loss remains an inevitable problem. Here, we present an inchworm actuator driven by two piezoelectric stacks with large carrying capacity and no backward motion which inherits advantages of the traditional inchworm piezoelectric actuators. Correspondingly, each clamping foot can be converted into a clamping unit or an extension unit utilizing a distinctive double-diamond flexure hinge. An approach utilizing the parasitic motion to realize the walker-pusher mode was proposed. Experimental results indicate that no-backward linear motion can be realized by walker-pusher mode, which utilizes the parasitic motion. The actuator achieved a maximum speed of 471.01 μm/s, a carrying load of 6.1 kg and an output force of 11.76 N when the frequency and voltage were 19 Hz and 150 V. This work confirms that it is feasible to design inchworm actuator driven by two stacks working in walker-pusher mode with no backward motion.

Cotton (Gossypium hirustum L.) as well as other crops are asking for an effective production with cost reduction and environment stewardship globally, especially in the developing countries. A new cotton planting strategy should be possible by shortening the growth season (less than six months rather than seven to eight months by late sowing and early harvesting) with low nitrogen (N) and high density. Therefore, a two-year (2018–2019) field experiment was conducted with a split plot design, two planting densities (D1, 6 plants m−2; D2, 8 plants m−2) as the main plot and three N rates (150, 180 and 210 kg ha-1 referred as N1, N2, and N3, respectively) as the subplot, to determine the effects of planting density and N rate on cotton yield and biomass accumulation. Results showed that, averaged across years, cotton yield was greater for treatment D2 as compared with that in D1, and N3 did not differ from that in N2 but was greater than that in N1. The highest lint yield (1271.2 kg ha-1) was achieved in D2N2 which no differ from that in D2N3 and D1N3. The maximal biomass (K) was achieved in treatment D2N2 (1032.4 g m−2) with the average speed (VT) of 21.2 g m−2 d-1 during the fast accumulation period, and the maximal growth rate (Rm, 20.5 g m−2 d-1) of sink during the cotton growth and development. Seedcotton yield was positively correlated (r = 0.72) to the plant biomass during flowering and boll-setting period, and the yield was contributed directly by sink with a coefficient as high as 0.70, while it was contributed indirectly by flow and source with coefficients of 0.63 and 0.59, respectively. The results suggest that N reduction is feasible due to a quicker bulk sink biomass accumulation under a higher planting density, which benefits efficient cotton production in the Yangtze River Valley, China, and areas with similar ecology.

In this paper, the detection performances of carbon black (CB) for bisphenol A (BPA) can be greatly improved by using a surfactant of cetyltrimethylammonium bromide (CTAB). The cyclic voltammetry (CV) behavior of CTAB/CB for BPA can be improved 6 times, compared with CB. The hydrophobicity of the CTAB long-chain alkyl end can enhance the enrichment ability of BPA. Meanwhile, CB can act as an electron transmission bridge to accelerate the electrons transfer to external circuit, thereby improving the sensing signal of CTAB/CB sensor for BPA. The sensor displays a linear range of 0.04 to 0.99 μM, a low detection limit of 0.013 μM and has good reproducibility and selectivity. Finally, the sensor can also be successfully used for detecting BPA in actual samples including tap water and human urine.

Petroleum bulk properties such as API gravity are important parameters in petroleum system analysis. Three sags (the Bayindulan, Saihantala and Wuliyasitai Sags) in the Erlian rift basin of northern China provide interesting insights into the correlations between organofacies, maturity and oil fluid properties. The API gravity of oils in the three sags shows obvious differences, ranging from 17.0 to 30.9° for Bayindulan oils, 25.7–40.5° for Saihantala oils, and 32.8–41.9° for Wuliyasitai oils. Oil geochemical parameters indicate that the differences in oil fluid properties among the three sags can be attributed to the variations in organofacies and thermal maturity, consistent with the analysis of geochemistry and maceral composition of the source rocks in the three sags. Bayindulan oils were expelled from organofacies C with an extremely high initial hydrogen index (HIo) of 600–900 mg/g TOC in the early mature stage (

Graphical abstract, Highlights • Expressions of ACE2 and TMPRSS2 were observed in the extrapulmonary organs. • Direct infections of SARS-CoV-2 in extrapulmonary organs were observed in patients with COVID-19. • Clinical manifestation and management for extrapulmonary organ injuries in COVID-19 should be noticed. • There might be a relationship between the infection of extrapulmonary organs and positive SARS-CoV-2 test in recovered patients., At the end of 2019, the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in China. Currently, it is breaking out globally and posing a serious threat to public health. The typically clinical characteristics of COVID-19 patients were fever and respiratory symptoms, and a proportion of patients were accompanied by extrapulmonary symptoms including cardiac injury, kidney injury, liver injury, digestive tract injury, and neurological symptoms. Angiotensin converting enzyme 2 (ACE2) has been proven to be a major receptor for SARS-CoV-2 and could mediate virus entry into cells. And transmembrane protease serine 2 (TMPRSS2) could cleave the spike (S) protein of SARS-CoV-2, which facilitates the fusion of SARS-CoV-2 and cellular membranes. The mRNA expressions of both ACE2 and TMPRSS2 were observed in the heart, digestive tract, liver, kidney, brain and other organs. SARS-CoV-2 may have a capacity to infect extrapulmonary organs due to the expressions of ACE2 and TMPRSS2 in the cells and tissues of these organs. It seems that there is a potential involvement of ACE2 and TMPRSS2 expressions in the virus infection of extrapulmonary organs and the manifestation of symptoms related to these organs in patients with COVID-19. Here, we revealed the expressions of ACE2 and TMPRSS2 in extrapulmonary organs, and we also summarized the clinical manifestation and the management of extrapulmonary complications in patients with COVID-19.

PEGylated uricase is a promising anti-gout drug, but the only commercially marketed 10kDa mPEG modified porcine-like uricase (Pegloticase) can only be used for intravenous infusion. In this study, tetrameric canine uricase variant was modified by covalent conjugation of all accessible ɛ amino sites of lysine residues with a smaller 5kDa mPEG (mPEG-UHC). The average modification degree and PEGylation homogeneity were evaluated. Approximately 9.4 5 kDa mPEG chains were coupled to each monomeric uricase and the main conjugates contained 7-11 mPEG chains per subunit. mPEG-UHC showed significantly therapeutic or preventive effect on uric acid nephropathy and acute urate arthritis based on three different animal models. The clearance rate from an intravenous injection of mPEG-UHC varied significantly between species, at 2.61 mL/h/kg for rats and 0.21 mL/h/kg for monkeys. The long elimination half-life of mPEG-UHC in non-human primate (191.48 h, intravenous injection) indicated the long-term effects in humans. Moreover, the acceptable bioavailability of mPEG-UHC after subcutaneous administration in monkeys (94.21%) suggested that subcutaneous injection may be regarded as a candidate administration route in clinical trails. Non-specific tissue distribution was observed after administration of (125)I-labeled mPEG-UHC in rats, and elimination by the kidneys into the urine is the primary excretion route.

Let N be a non-trivial nest on X , Alg N be the associated nest algebra, and L : Alg N → B ( X ) be a linear mapping. In this paper, it is proved that L is a Lie triple derivation if and only if there exist a derivation d : Alg N → B ( X ) and a linear mapping h : Alg N → C I with h ( [ [ X , Y ] , Z ] ) = 0 for any X , Y , Z ∈ Alg N such that L = d + h on Alg N .

In this paper, the concept of generalized hermitian operators defined on a complex Hilbert space is introduced. It is shown that the spectrums and the Fredholm fields of generalized hermitian operators are both symmetric with respect to the real axis. Some other results on generalized hermitian operators are obtained.

It is proved that a Jordan algebra of compact operators which is closed is either an Engel Jordan algebra, or contains a nonzero finite rank operator; Moreover, it is showed that any solvable Jordan algebra of compact operators on an infinite dimensional Banach space is triangularizable.

Mixed solvent of 1-octanol and cyclohexane with 60% (by mass) 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction capacity and much lower toxicity. Although the extraction capacity of the new extractant is smaller than that of pure 1-octanol, 1-octanol solubility of the new extractant in aqueous phase is much smaller. Because of its physical properties of lower density, lower viscosity, and higher interfacial tension, the new extractant performed much better phase separation ability than pure 1-octanol. The new extractant showed certain selectivity when dealing with lactam oil. The mixed solvent of 1-octanol and cyclohexane with 60% (by mass) 1-octanol content is a promising extractant for caprolactam extraction.