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Purpose: With the rapid development of the digital economy, an increasing number of digitalized two-sided platforms have deployed the tying strategy to leverage their market power from the core two-sided product to other two-sided products in the competitive market, which transforms the competition among single platforms into that among platform ecological networks. To clarify the mechanism of the formation of the digital platform ecological networks, this paper aims to analyze the expansion and stability of platform ecology by exploring the impacts of network externalities and sellers’ heterogeneity on the tying strategy of two-sided platforms. Design/methodology/approach: This paper develops a game model of two-sided platforms based on Choi and Jeon (2021), which highlights the decisive influence of non-negative price constraints (NPC) on platforms’ tying motivation. Taking the operating systems market as an example, we expand from the perspective of platform service differences to relax the NPC and explore the internal logic of platform ecosystem expansion. Findings: Platforms have an incentive to charge lower prices or even subsidize buyers when the network externalities on the sellers’ side are relatively strong. When the product is highly differentiated and heterogenous, platforms are motivated to tie to capture more buyers with a lower price and grab excess profits from sellers. Eventually, tying is able to consolidate the two-sided platform ecological networks by excluding competitors, capturing user value and deterring entry. Originality/value: In order to describe the characteristics of platform ecological network more generally, this paper extends the research based on the analyses of Choi and Jeon (2021) by (1) allowing horizontal differences between tied products and (2) relaxing the NPC. Unlike Choi and Jeon (2021), this paper allows platforms to charge users of two-sided platforms at negative prices (or to subsidize them). (3) Setting simultaneous pricing in two-sided platforms. Classical two-sided market theory stresses that the presence of cross-network externalities can give rise to a “chicken and egg” problem.

The number of semiconducting MXenes with direct band gaps is extremely low; thus, it is highly desirable to broaden the MXene family beyond carbides and nitrides to expand the palette of desired chemical and physical properties. Here, we theoretically report the existence of the single-layer (SL) dititanium oxide 2H-Ti2O MOene (MXene-like 2D transition oxides), showing an Ising superconducting feature. Moreover, SL halogenated 2H- and 1T-Ti2O monolayers display tunable semiconducting features and strong light-harvesting ability. In addition, the external strains can induce Weyl fermions via quantum phase transition in 2H-Ti2OF2and Ti2OCl2monolayers. Specifically, 2H- and 1T-Ti2OF2are direct semiconductors with band gaps of 0.82 and 1.18 eV, respectively. Furthermore, the carrier lifetimes of SL 2H- and 1T-Ti2OF2are evaluated to be 0.39 and 2.8 ns, respectively. This study extends emerging phenomena in a rich family of 2D MXene-like MOene materials, which provides a novel platform for next-generation optoelectronic and photovoltaic fields.

Based on the density functional theory calculations, we report the stability, electron structure, and potential applications in single-layer (SL) NiX2(X = S, Se, and Te) that show high thermal, dynamical, and mechanical stability and possess ultralow isotropic Young’s modulus. Moreover, these NiS2, NiSe2, and NiTe2monolayers have high energy storage capacities of 874, 496, and 342 mA h g–1and low diffusion energy barriers of 0.23/0.24/0.27 and 0.12/0.13/0.12 eV when used as anodes in lithium-ion batteries and sodium-ion batteries, respectively. SL NiS2and NiSe2show semiconducting traits in their freestanding crystals. Specifically, the 2D NiTe2monolayer is determined to be an intrinsic superconductor with a transition temperature (Tc) of ∼2.24 K. The Tccan be improved to 5.48 K when subjected to an in-plane compressive strain of 6%. These results enrich the family of transition metal-based 2D materials with multifunctionality and facilitate further experimental efforts toward next-generation nanodevices.

For seeking new types of two-dimensional (2D) materials based on honeycomb borophene, honeycomb borophene fragments stabilized by Li atoms in sandwich molecules are found theoretically. This is based on our understanding on the hexagonal B6ring with two-electron deficiency and Li atoms as suitable electron donors. In these sandwich molecules, each hexagonal B6ring unit of honeycomb borophene fragments is sandwiched between two Li atoms, forming stable sandwich lithium salts due to electron transfer from Li atoms to the borophene fragment. In the sandwich lithium salts, the middle planar layer of honeycomb borophene fragment polyanions is sandwiched between two Li+layers. Owing to the large size effect, the lithium salt (7Li)7+B2414–(7Li)7+including the planar polyanion sheet B2414–with a high valence of −14 can serve as an electron reservoir unusually exhibiting two different behaviors of the electron donor and electron acceptor. Furthermore, material property calculations show that this 2D sandwich lithium salt (Li2B2sheet) is demonstrated to be thermally and mechanically stable. Remarkably, the Li2B2sheet is not only a metal 2D material with a Dirac cone but also an intrinsic superconductor with the superconducting transition temperature Tc≈ 6.2 K. This work provides a new potential two-dimensional material for practical application.

In the face of environmental pollution and an energy shortage, how to reduce the cost of a noble metal catalyst in clean energy such as the fuel cell system and improve its electrocatalytic performance is one of the hot issues in this field. Here, a facile stepwise co-reduction route for synthesizing a series of PdFe/Cu catalysts with surface reconstruction is investigated and the ethanol oxidation reaction (EOR) performance is explored. The greater exposure of Pd active sites makes it excellent in EOR in alkaline media compared to the homemade and commercial Pd black catalyst. The mass activity of PdFe/Cu (794.97 mA mg−1Pd) is 2.52 times that of the Pd black catalyst (315.64 mA mg−1Pd). This kind of PdFe/Cu catalyst shows enhanced mass current density (255.66 mA mg−1Pd) after the 1800 s chronoamperometry test and only exhibits a decay of 1.4% after accelerated 500-cycle measurement. The enhanced EOR performance may be due to the change in the electronic structure of Pd caused by synergistic and strain effects among Pd, Fe, and Cu. This work provides an effective and kindly strategy to synthesize electrocatalysts with superior activity and durability in relation to EOR.

This retrospective study aimed to use preoperative and contrast-enhanced ultrasound (CEUS) factors to assess and reveal risk factors of early recurrence (ER) in patients with hepatocellular carcinoma (HCC). We enrolled 141 patients with primary HCC who had undergone surgical resection. The assessment of the CEUS scan includes (a) the maximum diameter of the lesion, (b) the tumor echogenicity of gray-scale ultrasound (US), (c) the morphology of the tumor, (d) the margin of the tumor, (e) the peripheral hypoechoic halo, (f) tumor necrosis, (g) nutritional arteries shown by tumors, (h) ultrasonography for diagnosis of cirrhosis, and (i) the timer on the US screen displayed the time elapsed from the saline flush and was used to determine time to washout. According to the degree of the phase, the washout rate is divided into four grades, namely, levels 1 to 4. ER is defined as the time between resection and recurrence within 12 months after surgery. Risk factors for ER HCC were analyzed. Predictors of ER on a univariate logistic regression analysis in CEUS are size, washout rate, morphology, center necrosis, and feeding artery appearing in the tumor. Multivariate analysis results indicated that feeding artery, microvascular invasion (MVI), and washout rate were independent risk factors for ER. The relative high risk of ER for washout rate 1, 2, 3, and 4 were 29.3%, 43.2%, 53.1%, and 71.4%, respectively. The appropriateness of hepatectomy in the treatment of single lesion HCC should be carefully considered when the washout rate was 4.

Tin hybrid perovskite solar cells (TPSCs) have emerged as the most promising candidate to the lead counterparts for the low toxicity and high theoretical efficiency. However, the easy Sn2+oxidation and related defects hinder further efficiency and stability improvement. Therefore, a facile Lewis base molecule of 4-amino-3-hydroxybenzoic acid (4A3HA) is employed in the perovskite precursor to coordinate with the under-coordinated Sn2+ions and passivate the Sn defects. The effective suppression of the formation of Sn vacancy also has been verified from the density functional theory calculations. The 4A3HA modification significantly suppresses the trap-mediated recombination of Sn perovskite film. Accordingly, these benefits deliver a high power conversion efficiency (PCE) of 13.43% for TPSCs with notably improved on-shelf and thermal stability.

The purpose of reverse engineering is to convert a large points cloud into a CAD model. Parameters extraction for rotational surface from measure data is an important problem in reverse engineering. Rotational axis is a crucial parameter of rotational surface. In this paper, random sampling consensus algorithm combined with Least-Squares method is used to extract the rotational axis of rotational surface. Experimental results show effectiveness, robustness and accuracy of this proposed approach.

The purpose of reverse engineering is to convert a large points cloud into a CAD model. Parameters extraction for extruded surface from measure data is an important problerm in reverse engineering. Extruded direction is a crucial parameter of extruded surface. In this paper, random sampling consensus algorithm combined with Least-Squares method is used to extract the extruded direction of extruded surface. Experimental results show effectiveness, robustness and accuracy of this proposed approach.

An important problem in customer recognition process is to select the most valid customer features. The authors present a new optimisation algorithm that combines a global optimisation algorithm called the nested partitions algorithm and the simulated annealing method. The resulting hybrid algorithm NP/SA retains the global perspective of the nested partitions algorithm and the local search capabilities of the simulated annealing method. A detailed application of the new algorithm to a customer recognition problem is also presented. The numerical results suggest that the new framework has great computation efficiency and convergence speed and is very efficient for a difficult customer feature selection problem.

1-Propyl- and 1,3-dimethyl-8-p-sulfophenylxanthine (PSB-1115 and SPT) were used as starting compounds for the development of adenosine A3c receptor antagonists with a sulfonamide structure. Since standard reactions for sulfonamide formation failed or resulted in very low yields, we developed a new method for the preparation of sulfonamides. p-Nitrophenoxide was used as a suitable leaving group with well balanced stability−reactivity properties. A large variety of amines, including aniline, benzylamine, phenethylamine, propylamine, butylamine, 2-hydroxyethylamine, aminoacetic acid, and N-benzylpiperazine reacted with p-nitrophenoxysulfonylphenylxanthine derivatives yielding the desired sulfonamides in satisfying to very good yields. The obtained sulfonamides were much more potent at A3c receptors than the parent sulfonates. The most active compound of the present series was 8-[4-(4-benzylpiperazide-1-sulfonyl)phenyl]-1-propylxanthine (11, PSB-601) exhibiting a Ki value of 3.6 nM for the human A3c receptor combined with high selectivity versus the other human adenosine receptor subtypes (575-fold versus A1, 134-fold versus A2A, and >278-fold versus A3).

Objective: To construct a PC 12 cell strain with neuronal differentiation, and observe the apoptosis and proliferation activity effects induced these cells by Amyloid beta-Protein (Aβ-43). Methods: 1) PC12 cells in logarithmic growth phase were subcultured for 24 h. After the culture fluid was changed, the cells were treated with Rat-β-NGF and cultured for 9 days. 2) Neuronal differentiation of PC 12 cells in logarithmic growth phase were divided into four groups: control group (0), experimental group (1), experimental group (2) and experimental group (3). The concentrations of Aβ in the four groups were 0 μmol/L, 1.25 μmol/Land 5 μmol/L, respectively. The cells were harvested at 24, 48 and 72 h later and stained with Annexin V-FITC/PI after centrifugation and washing. Then flow cytometry was conducted to examine the apoptosis percentage. 3) NGF-induced PC12 cells were selected and Aβ with different concentrations was added. The final concentrations of Aβ were 0 μmol/L, 1.25 μmol/L, 2.5 μmol/L and 5 μmol/L, respectively. After the cells were incubated in an atmosphere of 5% CO2at 37 °C in an incubator for 72 h, the OD values were examined. Results: 1) Neuronal differentiated PC12 cell lines were successfully established. 2) Flow cytometric examination indicated that Aβ (1.25, 2.5, and 5.0 μmol/L) could effectively induce apoptosis of neuronal-differented cells at the 24 h, 48 h and 72 h time points. 3) Aβ (0–5.00 μmol/L) had no obvious effect on proliferation or restraining of the neuronal differentiation of the PC 12 cells after a 72 h interacting process. Conclusion: This investigation revealed successful neuronal differentiation of the PC 12 cell strain. The induction of apoptosis of the neurocytes by various concentrations of Aβ was observed and the influence of Aβ on induced proliferation of PC 12 cells by Rat-β-NGF was revealed. This study may provide basis for future research on the molecular cure of AD and interdiction of AD evolution.

Objective: to explore the frequency and significance of ApoE gene polymorphisms in Chinese patients with atherosclerotic cerebral infarction (ACI). Methods: Polymerase chain reaction and gene sequencing, single nucleotide polymorphisms of ApoE gene were used to analyze 33 cases of patients with ACI and 35 controls. Results: The frequencies of ApoE gene single nucleotide polymorphisms 465C/G, 462C/G and 451 delC in the ACI group were significantly higher than those in the control group (P<0.05). The prevalence of polymorphism 486G/T in the control group was significantly higher than that in the ACI group (P=0.011). Conclusions: 465C/G, 462C/G and 451 delC polymorphisms might be associated with ACI. 486GT allale might have protective effect on the pathogenesis of ACI.

Adenosine is a physiological nucleoside which acts as an autocoid and activates G protein-coupled membrane receptors, designated A1, A2A, A2B and A3. Adenosine plays an important role in many (patho)physiological conditions in the CNS as well as in peripheral organs and tissues. Adenosine receptors are present on virtually every cell. However, receptor subtype distribution and densities vary greatly. Adenosine itself is used as a therapeutic agent for the treatment of supraventricular paroxysmal tachycardia and arrhythmias and as a vasodilatatory agent in cardiac imaging. During the past 20 years, a number of selective agonists for A1, A2A and A3 adenosine receptors have been developed, all of them structurally derived from adenosine. Several such compounds are currently undergoing clinical trials for the treatment of cardiovascular diseases (A1 and A2A), pain (A1), wound healing (A2A), diabetic foot ulcers (A2A), colorectal cancer (A3) and rheumatoid arthritis (A3). Clinical evaluation of some A1 and A2A adenosine receptor agonists has been discontinued. Major problems include side effects due to the wide distribution of adenosine receptors; low brain penetration, which is important for the targeting of CNS diseases; short half-lifes of compounds; or a lack of effects, in some cases perhaps due to receptor desensitisation or to low receptor density in the targeted tissue. Partial agonists, inhibitors of adenosine metabolism (adenosine kinase and deaminase inhibitors) or allosteric activators of adenosine receptors may be advantageous for certain indications, as they may exhibit fewer side effects.

Two hundred and five histologically confirmed cases of nasopharyngeal carcinoma (NPC) in southern China, and an equal number of matched controls, were investigated for their dietary habits, occupational exposure, use of tobacco and alcohol, history of relatives with NPC, and IgA against Epstein-Barr virus (EBV) capsid antigen (IgA/VCA). Positive IgA/VCA and intake of salted fish were associated with a strong excess risk of NPC. The association persisted after adjustment for other factors. The combination of salted fish and EBV was strongly associated with NPC, and more so than EBV or salted fish per se. Multivariate analyses showed that IgA/VCA was the most important predictor of NPC, and salted fish the second most important. These results suggest that EBV has a strong effect on the development of NPC. The exclusion of EBV and genetic factors in earlier epidemiological studies may have resulted in an overestimation of salted fish as important etiological factor causing NPC.

In the city of Guangzhou (Canton) and its surroundings nasopharyngeal cancer (NPC) constitutes about 32% of all cancer and is therefore the most common kind of cancer. Three types of etiological factors seem to be involved: 1) a hereditary factor, 2) Epstein-Barr virus, and 3) external factors in food and water. An epidemiological study has been started in the Guangzhou area with interviews of NPC cases, matching controls and mothers of the cases and controls concerning especially food and environmental factors and infections in childhood. The questions put to the controls and cases covered the last seven years and the age of ten, while those to the mothers covered the first three years of life and the age of ten for the controls and cases. Results are now available for 140 cases, 140 controls and the corresponding living mothers. They indicate that salted fish, particularly of Cantonese style, was consumed more by NPC cases than by controls and also had more frequently been given to weaning children in whom NPC later developed. Furthermore, salted vegetables and salted pork were consumed to a greater extent by NPC cases than by controls. Drinking of polluted water in childhood was more common among the NPC cases. Consumption of fresh fruit was more rare among the cases. Most of the NPC cases had a positive VCA-IgA titre.

We propose a scheme to control the coupling between the charge qubit and the nitrogen-vacancy center ensemble (NVCE). The coupling is mediated by a large Josephson junction (JJ) and a flux qubit. The large JJ can be treated classically and behaves like an effective inductance to switch the coupling between the charge and flux qubits. The flux qubit serves as a bridge to couple the NVCE and the charge qubit, and quantum state transfer can be implemented, with the NVCE acting as a memory unit. The hybrid circuit can reinforce various advantages: controllability of the charge qubit and robust spin coherence of the NVCE. [ABSTRACT FROM AUTHOR]