Constructivism in online learning : a literature review

The purpose of this paper is to look at the interaction of constructivist-based approaches, adult learning characteristics and six online learning issues. Constructivist learning environments allow learners to build their own meaning and understanding from learning resources and circumstances. Constructivists claim that learners accumulate new knowledge by themselves and use this to pile up previous knowledge and experiences. The learner is the learning focus, and the instructors act as facilitators or guides, which provide appropriate and enriching supplies. This theory supports well the adult style of learning. Based on constructivism, the online instructor is a facilitator to monitor and provide a safe, positive, and motivating online learning environment, and a tutor to provide the supporting skills and knowledge to each individual. Compared to traditional education, online learning has some outstanding features, such as the setting overcomes geographic problems and the learners could go to the virtual classroom anytime and anywhere if they have the accesses to the Internet. This paper focuses on the adult learning group, along with the online learning benefits and some issues that occur among the technologies and human subjects

PD_NGSAtlas: a reference database combining next-generation sequencing epigenomic and transcriptomic data for psychiatric disorders

Background: Psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BP) are projected to lead the global disease burden within the next decade. Several lines of evidence suggest that epigenetic- or genetic-mediated dysfunction is frequently present in these disorders. To date, the inheritance patterns have been complicated by the problem of integrating epigenomic and transcriptomic factors that have yet to be elucidated. Therefore, there is a need to build a comprehensive database for storing epigenomic and transcriptomic data relating to psychiatric disorders. Description: We have developed the PD_NGSAtlas, which focuses on the efficient storage of epigenomic and transcriptomic data based on next-generation sequencing and on the quantitative analyses of epigenetic and transcriptional alterations involved in psychiatric disorders. The current release of the PD_NGSAtlas contains 43 DNA methylation profiles and 37 transcription profiles detected by MeDIP-Seq and RNA-Seq, respectively, in two distinct brain regions and peripheral blood of SZ, BP and non-psychiatric controls. In addition to these data that were generated in-house, we have included, and will continue to include, published DNA methylation and gene expression data from other research groups, with a focus on psychiatric disorders. A flexible query engine has been developed for the acquisition of methylation profiles and transcription profiles for special genes or genomic regions of interest of the selected samples. Furthermore, the PD_NGSAtlas offers online tools for identifying aberrantly methylated and expressed events involved in psychiatric disorders. A genome browser has been developed to provide integrative and detailed views of multidimensional data in a given genomic context, which can help researchers understand molecular mechanisms from epigenetic and transcriptional perspectives. Moreover, users can download the methylation and transcription data for further analyses. Conclusions: The PD_NGSAtlas aims to provide storage of epigenomic and transcriptomic data as well as quantitative analyses of epigenetic and transcriptional alterations involved in psychiatric disorders. The PD_NGSAtlas will be a valuable data resource and will enable researchers to investigate the pathophysiology and aetiology of disease in detail. The database is available at http://bioinfo.hrbmu.edu.cn/pd_ngsatlas/

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Investigation on failure behavior of collapse column in China's coal mine based on discontinuous deformation numerical method.

Karst collapse column is a serious geological disaster in China's coal mines. There are various karst collapse columns in coal mine areas, such as Huainan, Huaibei, Xingtai, Lu'an. And they have seriously affected mining safety and geological environment. The present research is focused on analyzing subsidence mechanism and dynamic collapse process. Based on mechanical analysis of thin plate theory, a detailed model of collapse column slipping and bending fracture is constructed to gather the critical conditions of the collapse column roof. The sensitivity parameters analysis shows that both the radius and roof thickness of cave have a great influence on the sliding instability and bending fracture. Meanwhile, the buried depth also affects bending failure. The discontinuous deformation analysis (DDA) method is used to simulate and analyze the collapse process. The numerical results indicate that the stability of inverted funnel collapse column is dominated by the bending stress of roof strata. The movement of columnar collapse column is mainly caused by sliding instability. However, the funnel collapse column is relatively stable, and does not change in the same condition. The displacement field analysis shows that the collapse range of inverted funnel collapse column is obviously larger than that of columnar collapse column, in which its maximum displacement is approximately 1.5 times that of the columnar collapse column. There is no large area collapse on the upper part of the funnel collapse column, and the block system is relatively stable. The principal stress field analysis proves the above results

Hypoglycemic effect of Moringa oleifera leaf extract and its mechanism prediction based on network pharmacology

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia, which poses a serious threat to human health. Moringa oleifera Lam is a medicinal and edible plant with various physiological functions. However, its main hypoglycemic components and mechanisms are still unclear. In this study, network pharmacology and bioinformatics were used to analyze the potential bioactive substances of M. oleifera leaf extract (MOLE) and its hypoglycemic mechanism. Studies have shown that MOLE has the effect of increasing glucose consumption in insulin resistant-HepG2 cells. MOLE was found to contain 975 compounds by ultrahigh performance liquid chromatography-mass spectrometry (UHPLC-MS). Network pharmacology analysis indicated that the main active component was robinetin and the identified core genes were AKT1 and GAPDH. KEGG pathway enrichment analysis showed that the hypoglycemic effect of MOLE may be closely related to the PI3K-Akt signaling pathway. This study revealed the possible active components and mechanisms of action of M. oleifera for hypoglycemia, laying the theoretical foundation for subsequent studies

Tuning the Pd-catalyzed electroreduction of CO2 to CO with reduced overpotential

Developing selective and efficient catalysts is highly desirable for electrochemical CO2 reduction (ECR) to fuels and chemicals. Pd can strongly bind *COOH but weakly bind *CO, thus resulting in CO as a product. However, proton reduction also occurs severely on the surface of Pd, leading to low CO selectivity. Here we found that the ECR to CO can be greatly enhanced by controlling the Pd–ceria interface and doping with tellurium atoms. Notably, a very high mass activity of 92 mA mgPd−1 (at 1.0 V vs. reversible hydrogen electrode) for CO formation was achieved, significantly surpassing previously reported Pd catalysts (35 mA mgPd−1 at −1.0 V). The Pd catalysts comprising CeOx displayed more positive onset potentials than the Pd catalysts in the absence of CeOx, enabling ECR to CO at −0.6 V (vs. RHE). The modified Pd catalyst also afforded an unprecedented CO faradaic efficiency of over 84% at a low Pd loading (<3 wt%). Density functional theory calculations revealed that the Pd atoms located between the Te dopant and CeO2 promoted CO formation, thus improving CO2 conversion efficiency

Nitrogen fixation by Ru single-atom electrocatalytic reduction

Nitrogen fixation under ambient conditions remains a significant challenge. Here, we report nitrogen fixation by Ru single-atom electrocatalytic reduction at room temperature and pressure. In contrast to Ru nanoparticles, single Ru sites supported on N-doped porous carbon greatly promoted electroreduction of aqueous N2 selectively to NH3, affording an NH3 formation rate of 3.665 mgNH3h−1mg−1Ru at −0.21 V versus the reversible hydrogen electrode. Importantly, the addition of ZrO2 was found to significantly suppress the competitive hydrogen evolution reaction. An NH3 faradic efficiency of about 21% was achieved at a low overpotential (0.17 V), surpassing many other reported catalysts. Experiments combined with density functional theory calculations showed that the Ru sites with oxygen vacancies were major active centers that permitted stabilization of *NNH, destabilization of *H, and enhanced N2 adsorption. We envision that optimization of ZrO2 loading could further facilitate electroreduction of N2 at both high NH3 synthesis rate and faradic efficiency

Proton Exchange Membrane Electrode Assembly for Ammonia Electrosynthesis from Nitrate

Green ammonia synthesis and elimination of nitrate pollution from water are two global challenges that need to be dealt with. Electrocatalytic nitrate reduction to ammonia (e-NRA) using renewable electricity has been considered a potential solution to these challenges simultaneously. Although great research progress has been achieved in developing high-activity catalysts, insufficient attention has been paid to the electrolyzer design, which also has a vital impact on the e-NRA performance. Herein, we first abandoned anion exchange membranes due to the inevitable high nitrate permeability and then studied a proton exchange membrane electrode assembly (PEMEA) coupled with high-performance oxide-derived Cu nanoneedle cathodes toward practical application of e-NRA. Our results illustrated that the architecture of cathodes should be rationally designed to overcome the competing hydrogen evolution reaction aggravated by the utilization of proton exchange membranes. As a result, an optimized PEMEA achieved a high ammonia faradic efficiency of 90% at a high current density of 400 mA cm–2 in an electrolyte with 0.1 M nitrate concentration, and the corresponding ammonia yield was 1.6 mmol h–1 cm–2. In addition, nearly 100% conversion of nitrate to ammonia was demonstrated in the wastewater treatment of actual enterprises. We believe this work will facilitate the industrialization process of e-NRA