Molecular Kondo effect in flat-band lattices

The Kondo effect of a single magnetic impurity embedded in the Lieb lattice is studied by the numerical renormalization group. When the band flatness is present in the local density of states, it quenches the participation of all dispersive electrons in the Kondo singlet formation, and reduces the many-body Kondo problem to a two-electron molecular Kondo problem. The two-electron analog of the many-body Kondo singlet, a quantum entanglement of two spins, is stable at low temperature, and the impurity contributions to thermodynamical and dynamical quantities are qualitatively different from that obtained in the conventional Kondo effect in systems without flat bands. The existence conditions of the molecular Kondo effect in narrow band systems are also discussed

The Age of Extreme

The COVID-19 pandemic caught the entire world off guard; presenting policy-makers with various thorny issues to address. This article probes the intersection of the COVID-19 pandemic and human rights. We argue that, on the one hand, there is a growing concern about excessive and disproportionate restrictions on human rights under the guise of ‘emergency powers’. On the other, the fact that rights are not taken seriously renders every effort to ward off the infectious disease faltering. Hence, we suggest that the COVID-19 pandemic should serve as a wake-up call for countries to step up their rights commitments. Despite the exceptional nature of the pandemic, human rights must remain at the heart of the States’ legal and policy choices

Geometrically nonlinear buckling analysis of truss with length imperfection subjected to mechanical and thermal load using hybrid FEM

This paper presents a novel hybrid FEM-based approach to establish the mathematical model for solving the nonlinear buckling problem of truss systems with length imperfection under mechanical and thermal load. due to constant temperature change-based hybrid FEM. The proposed approach deals with establishing hybrid types of truss elements, including perfect truss elements without thermal deformation and truss elements with length imperfection and thermal deformation. The equilibrium equation of both truss elements is established based on compatibility relationships considering geometric nonlinearity. The hybrid global equilibrium equations of truss systems are developed by assembling constructed perfect truss elements without thermal deformation and truss elements with length imperfection and thermal deformation. The incremental-iterative algorithm based on the arc-length method is used to establish calculation programs to solve the hybrid global equilibrium equation for investigating the geometrically nonlinear buckling behavior of the truss system. The numerical test is presented to investigate the buckling and post-buckling behavior of truss systems having some elements with length imperfection under thermal and mechanical load

Chemical composition and antibacterial activities of essential oils from fruits of Melicope pteleifolia (Champ. Ex Benth.) T.G. Hartley grown in Lam Dong Province, Vietnam

In the present study, chemical composition and antibacterial properties of essential oil obtained from the aerial parts of the Melicope pteleifolia (Champ. ex Benth.) T.G Hartley in Dalat were evaluated. Essential oil was isolated through hydro-distillation. Twenty-nine constituents comprising 100% of the essential oil were characterized by gas chromatography/mass spectrometry (GC-MS) techniques. The major compounds in the essential oil were (+)-Sabinene (34.73%), Cis-α-bergamotene (13.15%), Z-α-trans-bergamotol (5.28%), β-mycrene (4.98%), and 1,3,6-octatriene, 3,7-dimethyl-(4.71%). Antibacterial activities of Melicope pteleifolia essential oil were investigated against Gram-positive and-negative bacteria. Results showed significant activities against Streptococcus pyogenes and Escherichia coli using an agar well diffusion method. The application of this essential oil in preventing and eliminating bacteria could be useful in fields as medicine and cosmetics.

ĐIỀU TRA TÌNH HÌNH CỎ LỒNG VỰC PHÁT SINH TRỞ LẠI TRÊN RUỘNG LÚA GIEO SẠ SAU KHI SỬ DỤNG THUỐC TRỪ CỎ Ở THỪA THIÊN HUẾ

Studying herbicide resistance in Vietnam is limited, and there are very few reports on the regrowth of weed after applying herbicides. A survey to investigate the cultivating habit and the barnyard grass regrowing in the direct-seeded rice fields after applying herbicides in Thua Thien Hue shows that the main labourers of rice cultivation are male with a low educational level to understand scientific and technical knowledge. The most common grass regrowing in direct-seeded rice fields after applying herbicides includes Barnyard grass (Echinochloa crus-galli), Grass-like fimbry (Fimbristylis miliacea), Bermuda grass (Cynodon dactylon), and Sprangletop (Leptochloa chinensis). The yield decreases from 12.1 to 14.0% because of regrowing of barnyard grass. The herbicides commonly used in Thua Thien Hue are Sofic 300EC (Pretilachlor) and Sunrice 15WDG (Ethoxysulfuron), but their effectiveness has decreased in recent time owing to farmers’ inappropriate spraying skills and the decrease in the effectiveness of herbicides. A more thorough assessment of the factors that cause grass regrowing after spraying herbicides is required for better weed management.Nghiên cứu sự kháng thuốc trừ cỏ ở Việt Nam còn hạn chế và có rất ít báo cáo về sự phát sinh của cỏ dại sau khi sử dụng thuốc trừ cỏ. Kết quả điều tra về tập quán canh tác và tình hình cỏ lồng vực phát sinh trở lại trên ruộng lúa sau khi sử dụng thuốc trừ cỏ ở Thừa Thiên Huế cho thấy lực lượng lao động chính canh tác lúa là nam giới, trình độ dân trí không cao nên khả năng tiếp thu kiến thức khoa học – kỹ thuật hạn chế. Các loại cỏ gây hại phổ biến trên ruộng lúa gieo sạ là cỏ lồng vực (Echinochloa crus-galli), cỏ chác (Fimbristylis miliacea), cỏ chỉ (Cynodon dactylon), cỏ đuôi phụng (Leptochloa chinensis) là các loại cỏ xuất hiện trở lại sau khi đã sử dụng thuốc trừ cỏ. Cỏ lồng vực mọc trở lại có thể gây giảm năng suất cây lúa 12,1–14,0%. Các loại thuốc trừ cỏ được sử dụng phổ biến là Sofic 300EC (Pretilachlor) và Sunrice 15WDG (Ethoxysulfuron). Hiệu quả thuốc trừ cỏ lúa có xu hướng giảm trong thời gian gần đây do kỹ thuật sử dụng và sự giảm hiệu quả của các sản phẩm thuốc trừ cỏ. Chúng tôi kiến nghị cần đánh giá đầy đủ hơn về các yếu tố gây nên tình trạng cỏ dại mọc trở lại sau khi phun thuốc để có định hướng quản lý cỏ dại tốt hơn

Cloning and expression of pigC gene in Escherichia coli

Prodigiosin (Pg), which is particularly of interest because of anticancer and antimicrobial activities, can be produced through the PigC-catalyzed condensation reaction of 4-methoxy-2, 2’-bipyrrole-5-carboxyaldehyde (MBC) and 2-methyl-3-amylpyrrole (MAP). Therefore, the PigC protein plays an important role in prodigiosin biosynthetic pathway. However, studies related to PigC protein have not been carried out in Vietnam yet. In this work, the pigC gene was cloned and expressed in Escherichia coli DH10B and BL21 (DE3), respectively. Using PCR and universal primers, we amplified a fragment of 3 kb covering entire coding region of the pigC gene from Serratia sp. strain M5. The pigC gene was inserted into pJET1.2 vector, and then transformed into E. coli DH10B. The sequence of a recombinant vector pJET1.2/pigC was evaluated by using whole colony PCR amplification. Sequence alignment results revealed that the obtained pigC gene possesses 71.5% and 75.4% of nucleotide identity in comparison with two strains, Serratia 39006 and Serratia sp. AS9 published in GenBank with their respective accession numbers of AJ833001 and CP002773. The recombinant vector pJET1.2/pigC was used to reamplify pigC, and the acquired amplicon was inserted into pET22b vector at the site of HindIII and XhoI. The clone E. coli BL21 (DE3) containing recombinant vector pET22b/pigC was expressed in the auto-induced medium. The presence of PigC protein in the lysate was identified as a 100 kDa band through Western Blot analysis using anti his-tag antibody. Afterward, the PigC protein was purified by Ni-NTA column, and its expression level was quantified through SDS-PAGE analysis. The results of our study provide a potential material for producing prodigiosin from recombinant protein in Vietnam

Differentiation Effect of Two Alkaloid Fractions from Vietnamese Lycopodiaceae on Mouse Neural Stem Cells

Various Lycopodium alkaloids have been studied for their various biological activities including anti-inflammatory, antioxidant, immunomodulatory, and neuroprotective activities. Moreover, these alkaloid compounds have high potential in the treatment of neuron degenerative disease. This study has been carried out to test the effect of Huperzia serrata (Thunb.) Trevis, and Lycopodium clavatum L alkaloid fractions on the mouse neural stem cells (NSCs). Firstly, the alkaloid fractions were used to verify its toxicity on NSCs. The multiple concentrations of alkaloid fractions from H. serrata (0.044; 0.088; 0.175; 0.35; 0.7; 1.4 mg/ml) and L. clavatum (0.031; 0.063; 0.125; 0.25; 0.50; 1.0; 2.0 mg/ml) have been used for the treatment of NSCs at period of 48h incubation. Results of the study suggested that the IC50 value of H. serrata and L. clavatum was 0.56 mg/ml and 0.50 mg/ml, respectively. Then, the NSCs were differentiated in the presence of 5 and 10 µg/ml of alkaloid fraction from H. serrata; 0.625 and 1.25 µg/ml of alkaloid fraction from L. clavatum for 6 days. Here, we observed the primary NSCs treated with alkaloid fraction extract from H. serrata showed the increased gene expression level of early neuron TUBB3 and neuron-specific cytoskeleton MAP2. On the other hand, the L. clavatum alkaloid fraction increased the expression of neural stem cell marker genes (Nestin and PAX6) and decreased neuron marker genes. In conclusion, these results established that alkaloid fraction from H. serrata promoted differentiation of the mouse NSCs to neuron cells, and L. clavatum extract had a capacity for stemness maintenance

Elevated Levels of Cell-Free Circulating DNA in Patients with Acute Dengue Virus Infection

BACKGROUND: Apoptosis is thought to play a role in the pathogenesis of severe dengue and the release of cell-free DNA into the circulatory system in several medical conditions. Therefore, we investigated circulating DNA as a potential biomarker for severe dengue. METHODS AND FINDINGS: A direct fluorometric degradation assay using PicoGreen was performed to quantify cell-free DNA from patient plasma. Circulating DNA levels were significantly higher in patients with dengue virus infection than with other febrile illnesses and healthy controls. Remarkably, the increase of DNA levels correlated with the severity of dengue. Additionally, multivariate logistic regression analysis showed that circulating DNA levels independently correlated with dengue shock syndrome. CONCLUSIONS: Circulating DNA levels were increased in dengue patients and correlated with dengue severity. Additional studies are required to show the benefits of this biomarker in early dengue diagnosis and for the prognosis of shock complication