The following article is devoted to the exploration of the relationship between teachers and students of China, whereas the typical traits of communication between Chinese teachers and students are ...not sufficiently explored to date. The aim of the research consists in consideration of the “teacher – student” relationships originality in comprehensive schools of the PRC. The tasks of the study are to analyze the influence of the Chinese philosophy in formation of the educational relations in China, to consider the place of a teacher and a student in the Chinese educational process, and to describe the level of communication between teachers and students of the PRC. The meta-analysis of the historical, philosophical, and psychological-pedagogical scientific works was served as the main method of the research. Results of the study. The analysis of the fundamental Chinese philosophical traditions and the official documents of PRC about the roles of the teacher and the students showed the social importance of the teacher`s role as a mentor, a leader, and an elder brother of the student, due to which we can observe the high level of respect among the students, what can also be followed by some degree of the fearfulness to teacher. The consideration of psychological-pedagogical scientific works of the foreign specialists had approved the following statements because the physical distance between a teacher and his students, and the structure of a classroom can create the certain differences between the subjects of education activity. Meanwhile modern Chinese educators endeavour to reduce the level of students` tension, building the academic and educational activities, which are based on the individual characteristics of students, and showing them the high level of attention and empathy.
Display omitted
•Catalyst preparation protocols strongly affect catalyst performance of Ru on titania (anatase) for the hydrogenation of levulinic acid.•Highest activity was obtained for a RuNO(NO3)3 ...precursor without an intermediate calcination step and 10% hydrogen in the reduction gas.•The information can be used to prepare improved Ru based catalysts for the catalytic hydrogenation of levulinic acid .
γ-Valerolactone (GVL) is a value-added renewable chemical with great potential and can be obtained from biomass by the hydrogenation of levulinic acid (LA) using metal-based catalysts, such as Ru/TiO2. We here report an in depth study of the effect of catalyst synthesis parameters on the performance of Ru/TiO2 (anatase), varying the nature of the Ru-precursor and the conditions of the calcination and/or reduction step. Catalyst performance was evaluated under batch conditions at a hydrogen pressure of 45bar and using either water (90°C) or dioxane (150°C) as solvent. The experiments showed that catalyst activity depends greatly on the Ru precursor used (RuCl3, RuNO(NO3)3, Ru(NH3)6Cl3). Best results when considering the turn-over frequencies (TOF) of the catalysts were obtained using the RuNO(NO3)3 precursor, whereas RuCl3 performed better when considering the initial rate based on Ru intake. An intermediate calcination step and the use of a hydrogen-rich sweep gas during the final reduction step were shown to have a negative impact on catalyst activity. Characterization of the fresh catalysts by BET and TEM provided valuable insight in the relation between the catalyst structure and its activity.
A highly efficient one-step approach to the macromonomer synthesis using modified aluminum complexes as catalysts of ring-opening polymerization (ROP) of ε-caprolactone and
,
-lactide was developed. ...The syntheses, structures, and catalytic activities of a wide range of aluminum salen complexes,
, functionalized with unsaturated alcohol (HO(CH
)
OCH=CH
) are reported. X-Ray diffraction studies revealed a tetragonal pyramidal structure for
. Among the complexes
-
, the highest activity in bulk ROP of ε-caprolactone and
,
-lactide was displayed by
, affording polyesters with controlled molecular weights at low monomer to initiator ratios (
up to 15,000 g mol
), relatively high polydispersities (Ð~1.8) and high number-average functionalities (
up to 85%).
Display omitted
•The hydrogenation of levulinic acid to γ-valerolactone was studied.•Reactions were performed using Ru/C in water in a batch set-up.•Mass transfer limitations play an important ...role.•4-hydroxypropionic acid is a clear intermediate.•Hydrogenation reaction was modelled using a LHHW mechanism.
γ-Valerolactone (GVL) is considered a very interesting green, bio-based platform chemical with high application potential for the production of both biofuels and biobased chemicals. In this contribution, we report a kinetic study on the hydrogenation of levulinic acid (LA) to 4-hydroxypentanoic acid (4-HPA) and the subsequent intramolecular esterification to GVL in water using Ru/C (3wt.% Ru) as the catalyst in a batch set-up. A large number of experiments was performed in a temperature range of 343–403K, a hydrogen pressure range from 30 to 60bar and initial LA concentrations between 300 and 2500molm−3. Experimental data, supported by calculation, indicate that intra-particle diffusion of LA and hydrogen affect the overall reaction rate and as such a heterogeneous model with both reaction and diffusion was used to model the data. The hydrogenation reaction of LA to 4-HPA was modelled using a Langmuir-Hinshelwood type expression whereas the reaction of 4-HPA to GVL was modelled as an equilibrium reaction occurring in the bulk of the liquid, catalyzed by a Brönsted acid, in this case LA and 4-HPA. A good fit between experiments and model was observed. The results were compared to a kinetic model without considering mass transfer and diffusion limitations.
Ti–44Al–5Nb–3Cr–1.5Zr (at%) β-stabilized intermetallic was synthesized by the electron beam casting and afterwards re-solidified by the high-gradient (300°Ccm−1) induction float zone (FZ) technique. ...FZ-processing led to the ordered microstructure creation consisting of volumetrically prevailing (γ+α2) lamellar colonies separated by minor seam-like γ-granular interlayers, and the least intergranular quota of β(Ti)/B2 phase. The optimum phase balance, submicron interlamellar spacing and strict alignment of lamellae along the thermal gradient were controlled by FZ-conditions. Unique microstructural adjustment enhances drastically the yield and ultimate strengths, Young's modulus and creep resistance. Thus the high-temperature limit of γ-TiAl(Nb,Cr,Zr) structural applicability could be expanded from 750–800°C towards 900–950°C.
Display omitted
•High-gradient induction float zone re-solidification of cast γ-TiAl(Nb,Cr,Zr) alloy.•Unique ordered phase microstructure engineering.•Drastic enhancement of both ambient and high-temperature mechanical properties
The bulk ring-opening polymerization (ROP) of ε-caprolactone using phosphazene-containing porous polymeric material (HPCP) has been studied at high reaction temperatures (130-150 °C). HPCP in ...conjunction with benzyl alcohol as an initiator induced the living ROP of ε-caprolactone, affording polyesters with a controlled molecular weight up to 6000 g mol
and moderate polydispersity (Ð~1.5) under optimized conditions (BnOH/CL = 50; HPCP: 0.63 mM; 150 °C). Poly(ε-caprolactone)s with higher molecular weight (up to M
= 14,000 g mol
, Ð~1.9) were obtained at a lower temperature, at 130 °C. Due to its high thermal and chemical stability, HPCP can be reused for at least three consecutive cycles without a significant decrease in the catalyst efficiency. The tentative mechanism of the HPCP-catalyzed ROP of ε-caprolactone, the key stage of which consists of the activation of the initiator through the basic sites of the catalyst, was proposed.
To enhance the fatigue, corrosion and wear behaviors of low-carbon casting steel 20GL (G21Mn5 in EN classification) it was subjected to the effects of severe plastic deformation induced by ultrasonic ...impact treatment (UIT) and the electric discharge surface alloying (EDSA) with molybdenum. The structural formations in the sub-surface layers were characterized by means of light microscopy, X-ray diffraction analysis and transmission electron microscopy (TEM). Several intermetallic phases were observed in the EDSA-induced layer. TEM studies of transition area between the EDSA layer and steel substrate (at a depth of 15–30μm) demonstrate that the combined EDSA+UIT process induces the formation of a dislocation-cell structure in the alloyed ferrite grains. Both the cell boundaries and separate dislocations are often blocked by fine intermetallic and/or carbide particles. SEM analysis of fatigue fracture surfaces reveals the subsurface crack nucleation in the UIT-processed specimens instead of superficial crack initiation observed in the pristine and EDSA-processed ones. This provides enhanced fatigue strength and prolonged lifetime of the steel specimens after UIT and EDSA+UIT processes. High molybdenum content supports the improved corrosion resistance and fine intermetallic precipitates in the Fe-Mo protective layer provide the increased hardness and wear resistance of the EDSA+UIT-treated specimens. Thus, the specimens underwent combined EDSA+UIT treatment were shown to exhibit simultaneously increased fatigue strength (by ~5%) in low cycle fatigue regime, anti-corrosion properties (by ~85%) and wear resistance (by ~43%) in comparison with those of the pristine steel G21Mn5.
•Combined electric discharge surface alloying (EDSA) and ultrasonic impact treatment (UIT)•Combined EDSA+UIT process is effective for the surface quality improvement of low carbon steel.•Enhanced corrosion behavior of the steel surface is provided by EDSA alloying with molybdenum.•Improved wear resistance is supported by fine precipitates dispersed in α-FeMo solid solution.•Subsurface fatigue crack nucleation is caused by UIT-induced compressive residual stresses.
Triple-negative breast cancer (TNBC) is aggressive and lacks targeted therapies. Phosphatidylinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways are frequently activated in TNBC ...patient tumors at the genome, gene expression and protein levels, and mTOR inhibitors have been shown to inhibit growth in TNBC cell lines. We describe a panel of patient-derived xenografts representing multiple TNBC subtypes and use them to test preclinical drug efficacy of two mTOR inhibitors, sirolimus (rapamycin) and temsirolimus (CCI-779).
We generated a panel of seven patient-derived orthotopic xenografts from six primary TNBC tumors and one metastasis. Patient tumors and corresponding xenografts were compared by histology, immunohistochemistry, array comparative genomic hybridization (aCGH) and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) sequencing; TNBC subtypes were determined. Using a previously published logistic regression approach, we generated a rapamycin response signature from Connectivity Map gene expression data and used it to predict rapamycin sensitivity in 1,401 human breast cancers of different intrinsic subtypes, prompting in vivo testing of mTOR inhibitors and doxorubicin in our TNBC xenografts.
Patient-derived xenografts recapitulated histology, biomarker expression and global genomic features of patient tumors. Two primary tumors had PIK3CA coding mutations, and five of six primary tumors showed flanking intron single nucleotide polymorphisms (SNPs) with conservation of sequence variations between primary tumors and xenografts, even on subsequent xenograft passages. Gene expression profiling showed that our models represent at least four of six TNBC subtypes. The rapamycin response signature predicted sensitivity for 94% of basal-like breast cancers in a large dataset. Drug testing of mTOR inhibitors in our xenografts showed 77 to 99% growth inhibition, significantly more than doxorubicin; protein phosphorylation studies indicated constitutive activation of the mTOR pathway that decreased with treatment. However, no tumor was completely eradicated.
A panel of patient-derived xenograft models covering a spectrum of TNBC subtypes was generated that histologically and genomically matched original patient tumors. Consistent with in silico predictions, mTOR inhibitor testing in our TNBC xenografts showed significant tumor growth inhibition in all, suggesting that mTOR inhibitors can be effective in TNBC, but will require use with additional therapies, warranting investigation of optimal drug combinations.
PDF
