Barriers to e-Learning During Crisis: A Capital Theory Perspective on Academic Adversity

The unprecedented coronavirus pandemic (COVID-19) presented new, daunting academic adversities to college students, especially those from underserved communities. This study provides a nuanced understanding of underserved students’ adversities in online distance education, based on an in-depth analysis of narratives of 220 students from a minority-serving institution in the United States. Informed by the capital theory, the study revealed six major barriers to e-learning: technical, cultural, environmental, balance, social, and financial barriers, and identified new underlying dimensions. Moreover, the study found that technical barriers are often coupled with other types of barriers and underserved students are more likely to experience multiple learning barriers. A variance model of influencing factors was proposed for e-learning outcomes. The paper highlights new digital divide in e-learning and provides practical implications for educational institutions to support underserved students in overcoming academic adversities and building educational resilience

Elucidation of the 1-phenethylisoquinoline pathway from an endemic conifer Cephalotaxus hainanensis

Cephalotaxines harbor great medical potential, but their natural source, the endemic conifer Cephalotaxus is highly endangered, creating a conflict between biotechnological valorization and preservation of biodiversity. Here, we construct the whole biosynthetic pathway to the 1-phenethylisoquinoline scaffold, as first committed compound for phenylethylisoquinoline alkaloids (PIAs), combining metabolic modeling, and transcriptome mining of Cephalotaxus hainanensis to infer the biosynthesis for PIA precursor. We identify a novel protein, ChPSS, driving the Pictet–Spengler condensation and show that this enzyme represents the branching point where PIA biosynthesis diverges from the concurrent benzylisoquinoline-alkaloids pathway. We also pinpoint ChDBR as crucial step to form 4-hydroxydihydrocinnamaldehyde diverging from lignin biosynthesis. The elucidation of the early PIA pathway represents an important step toward microbe-based production of these pharmaceutically important alkaloids resolving the conflict between biotechnology and preservation of biodiversity

Mg2+-dependent facilitation and inactivation of L-type Ca2+ channels in guinea pig ventricular myocytes

AbstractThis study aimed to investigate the intracellular Mg2+ regulation of the L-type Ca2+ channels in guinea pig ventricular myocytes. By adopting the inside-out configuration of the patch clamp technique, single channel currents of the L-type Ca2+ channels were recorded at different intracellular Mg2+ concentrations ([Mg2+]i). At free [Mg2+]i of 0, 10−9, 10−7, 10−5, 10−3, and 10−1 M, 1.4 μM CaM + 3 mM ATP induced channel activities of 44%, 117%, 202%, 181%, 147%, and 20% of the control activity in cell-attached mode, respectively, showing a bell-shaped concentration-response relationship. Moreover, the intracellular Mg2+ modulated the Ca2+ channel gating properties, accounting for alterations in channel activities. These results imply that Mg2+ has a dual effect on the L-type Ca2+ channels: facilitation and inhibition. Lower [Mg2+]i maintains and enhances the basal activity of Ca2+ channels, whereas higher [Mg2+]i inhibits channel activity. Taken together, our data from the application of an [Mg2+]i series suggest that the dual effect of Mg2+ upon the L-type Ca2+ channels exhibits long open-time dependence

Zinc-blende and wurtzite GaAs quantum dots in nanowires studied using hydrostatic pressure

We report both zinc-blende (ZB) and wurtzite (WZ) crystal phase self-assembled GaAs quantum dots (QDs) embedding in a single GaAs/AlGaAs core-shell nanowires (NWs). Optical transitions and single-photon characteristics of both kinds of QDs have been investigated by measuring photoluminescence (PL) and time-resolved PL spectra upon application of hydrostatic pressure. We find that the ZB QDs are of direct band gap transition with short recombination lifetime (~1 ns) and higher pressure coefficient (75-100 meV/GPa). On the contrary, the WZ QDs undergo a direct-to-pseudodirect bandgap transition as a result of quantum confinement effect, with remarkably longer exciton lifetime (4.5-74.5 ns) and smaller pressure coefficient (28-53 meV/GPa). These fundamentally physical properties are further examined by performing state-of-the-art atomistic pseudopotential calculations

Relationship between driver gene mutations and clinical pathological characteristics in older lung adenocarcinoma

ObjectivesLung adenocarcinoma (LUAD) is the most common newly diagnosed malignant tumor in older people. As older patients age, organ function decreases, leading to increased adverse reactions to treatment. The epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase tyrosine (ALK) tyrosine kinase inhibitors (TKIs) therapy are more effective and well-tolerated than chemotherapy, while the rate of genetic testing and subsequent targeted treatment among older patients remains relatively low, the clinical benefit limitation for those patients. This study aims to investigate the mutation characteristics of LUAD diver gene and its relationship with clinicopathological features in older LUAD.Materials and methodsA total of 275 patients were diagnosed as LUAD and were over sixty years old. We utilized next-generation sequencing technology to detect and analyze gene mutations in postoperative tissue specimens, including EGFR, KRAS, ALK, ROS1, RET, MET, BRAF, HER2, PIK3CA and NRAS.ResultsA total of 90.18% (248/275) of older LUAD patients experienced genetic mutations. The EGFR (192, 69.82%) had the highest mutation rate among ten genes, followed by KRAS (21, 7.64%), MET (21, 7.64%), ERBB2 (15, 5.45%), RET (9, 3.27%), ALK (8, 2.91%), ROS1 (8, 2.91%), PIK3CA (6, 2.18%), BRAF (5, 1.82%) and NRAS (1, 0.36%). We also found thirty patients (15.63%) with EGFR mutations also having other gene mutations. The L858R mutation and exon19 deletion were the predominant EGFR mutations, accounting for 84.90% of EGFR-mutated patients. In addition, fifty-one kinds of EGFR mutations were detected, distributed in the protein tyrosine kinase catalytic domain (43, 84.31%), cysteine enriched domain (4, 7.84%), receptor binding domain (3, 5.88%), and EGFR transmembrane domain (1,1.96%). Ten cases of gene fusion mutation were detected. Two rare partner genes, PKHD1 (P60:R34) and STK39 (R33:S11), were detected by ROS1 gene fusion. RET gene fusion revealed a rare companion gene KCND2 (R11:K2). The EGFR mutations were more prevalent in female, non-smoking patients (p < 0.05), and the KRAS mutations were more common in male and smoking patients (p < 0.01). In addition, the BRAF mutations were more likely to occur in the right lung (p < 0.05).ConclusionOlder LUAD populations exhibit diverse genetic mutations, which may also exist simultaneously. Simultaneous detection of multiple genes by NGS can accelerate and enhance targeted treatment benefits for older LUAD patients, ultimately improving their quality of life