NaGdF4:Dy3+ nanocrystals: new insights into optical properties and energy transfer processes.

NaGdF4:Dy3+ nanocrystals (NCs) have been synthesized using a precipitation technique. The structural characteristics and morphology of the materials were analyzed using X-ray diffraction patterns and scanning electron microscopy images, respectively. The photoluminescence excitation spectra, emission spectra and decay curves of all samples were recorded at room temperature. The color feature of Dy3+ luminescence was estimated using CIE chromaticity coordinates and the correlated color temperature. The radiative properties of the Dy3+:4F9/2 level in the material were analyzed within the framework of JO theory. In NaGdF4:Dy3+ NCs, the energy transfer from Gd3+ to Dy3+ causes an enhancement in the luminescence of the Dy3+ ions. The rate of the processes taking part in the depopulation of Gd3+ ions was estimated. The energy transfer between Dy3+ ions leads to the luminescence quenching of NaGdF4:Dy3+. In this process, the dipole-dipole interaction, which is found by using the Inokuti-Hirayama model, is the dominant mechanism. The characteristic parameters of the energy transfer processes between Dy3+ ions have also been calculated in detail.

A new iridoid glucoside from the roots of Morinda officinalis.

A new iridoid glucoside, moridoside (1), and nine known compounds, asperulosidic acid (2), 6-O-epi-acetylscandoside (3), geniposidic acid (4), 2-hydroxymethylanthraquinone (5), 2-hydroxymethyl-3-hydroxyanthraquinone (6), damnacanthol (7), lucidine-ω-methyl ether (8), 2-hydroxy-1-methoxyanthraquinone (9), and 3,8-dihydroxy-1,2-dimethoxyanthraquinone (10) were isolated from the methanol extract of Morinda officinalis How. roots. Their structural identification was carried out based on the spectroscopic evidence. All compounds were evaluated for their nitric oxide (NO) production inhibitory activities in LPS-stimulated RAW264.7 macrophages. Compounds 5-7 significantly inhibited the production of NO with IC50 values of 28.4, 33.6, and 30.5 µM, respectively.

Circulation of human respiratory syncytial virus and new ON1 genotype in northern Viet Nam, 2017–2020

@#Objective: Human respiratory syncytial virus (RSV) is a primary cause of paediatric severe acute respiratory infection (SARI) worldwide, especially in developing countries. We investigated the genetic characteristics of RSV in northern Viet Nam to determine the prevalence and distribution of subtypes as well as the diversity and transmission patterns of genotypes. Methods: In two facilities, from January 2017 to December 2020, 1563 clinical specimens were collected from paediatric patients hospitalized with SARI and tested for RSV. Selected positive samples underwent sequencing analysis targeting the second hypervariable region of the G gene using next-generation sequencing. Results: The RSV positivity rate was 28.02% (438/1563 samples), and prevalence was highest in children aged <1 year (43.84%; 192/438). Subtype RSV-A accounted for 53.42% (234/438) of cases, RSV-B for 45.89% (201/438), and there was coinfection in 0.68% (3/438). Both subtypes cocirculated and peaked during August–September in each year of the study. Phylogenetic analysis showed that RSV-A samples belonged to the ON1 genotype, which has three subgenotypes: ON1.1, ON1.2 and ON1.3. However, we did not find the 72-nucleotide duplication in the second hypervariable region of the G gene, a characteristic of genotype ON1, in any RSV-A samples. RSV-B samples belonged to genotype BA9. Discussion: Our results provide additional molecular characterization of RSV infections in Viet Nam. Specially, our study is the first to report the absence of the 72-nucleotide duplication in the G gene of RSV-A genotype ON1 in Viet Nam, which may help in understanding the genetic evolution of RSV and be useful for vaccine development in the future.

Measurement of isomeric yield ratios of 99m,g;101m,g;102m,gRh in the natPd(γ,pxn) reactions with the bremsstrahlung end-point energies of 50-70MeV.

The isomeric yield ratios of 99m,gRh, 101m,ggRh, and 102m,gRh isomeric pairs produced from the natPd(γ,pxn) reactions were measured with the bremsstrahlung end-point energies of 50-, 55-, 60-, 65-, and 70-MeV at the 100MeV electron linac of the Pohang Accelerator Laboratory, Korea. The measurements were carried out with the activation method in combination with off-line γ-ray spectrometry. In order to improve the accuracy of the activity measurements, the separation of the overlapping γ-rays and the necessary corrections for the counting losses were made. The new experimental results are compared with the theoretical values of the TALYS-1.6 code.

Antimicrobial resistance and serotype distribution of streptococcus pneumonia isolates among children under 5 years of age, Hai Phong city, Viet Nam, during the period of 2006- 2007

Background: Streptococcus pneumonia (S.pneumoniae) is the main cause of acquired pneumonia in the community along with otitis media, sinusitis, septicemia and meningitis. Objectives: The study determined antimicrobial resistance and serotype distribution of Streptococcus pneumonia isolates from hospitalized children at Hai Phong Children's Hospital, Vietnam. Subjects and method: From June 2006 to September 2007, 80 pneumococccal isolates were tested for susceptibility to the 13 antibiotics and 84 pneumococcal isolates were serotyped. Results:Seventy-five percent of strains showed multi-drug resistance. Ninety percent of strains showed resistance to penicillin (48% intermediate and 42% fully resistant). In addition, 100% of isolates were resistant to cotrimoxazole, 74% of isolates were resistant to cephalexin; 71 % of isolates were resistant to erythroomycin and 58% were resistant to cefuroxxime. Almost all the isolates were susceptible to amoxicillin, cefotaxime, ceftriaxone, ceefepime, ofloxacin and 100% of isolates were susceptible to vancomycin. Among the 84 serotypes, 82% were included in the 23 valent pneumococcal polysaccharide vaccine including: 19F (30%), 23F (21 %), 14 (13%) and 6B (13%). Six other serotypes (13, 15C, 18, 11A, 15B and 6A) accounted for 12% of strains and 9 (11%) strains were untypeable. Conclusion: Pneumococcal antibiotics is spreading most rapidly among children in Vietnam, especially strains typs 19F and 23 F. Concerted efforts are necessary to prevent it spreading.\r\n", u'\r\n', u'

Human influenza like illness caused by adenovirus at Da Lac province in 2004

Background: Bacteria are among the common pathogens in Vietnam and other developing countries. Antibiotics are effective in the treatment, but the antibiotics gradually become ineffective due to drug resistance of bacteria, especially in children. The study on influenza virus in 2001-2003 has resulted in preventative activities against the acute respiratory tract infections in children.\r\n', u'Objectives: Determine the root cause bacterial infections and often determine the extent of antibiotic resistance of common pathogenic bacteria isolated in Hai Phong pediatric Hospital.\r\n', u'Subjects and method: At Microorganism Department of Hai Phong pediatric Hospital from January 2003 to December 2004, 558 trains of common pathogenic microorganisms were isolated from 0 -15 year old children clinical samples such as: blood, pus, cerebrospinal fluid, urine, stool...These samples of isolated microorganisms were also tested on their sensitiveness to several antibiotics.\r\n', u'Results:Findings showed that the 3 most frequently recognized bacterier out of 11 antibiotic sensitive tested species were: streptococcus pneumoniae (20.61%), neisseria (18.1%), E.coli (15.95%); and the most resisted antibiotics included: Co-trimoxazole, Chloramphenicol and Ampiciline. The staph was resistant to general Chlora, phenicol, Co-trimoxazol, and also sensitive to cefotacim, Amikacin. In the bacillus bacteria tested were resistant blue latex all, only works with Amikacin.\r\n', u'Conclusion: Its also found that every kind of tested bacterium had got various levels of sensitivity to different of antibiotics.\r\n', u'

Isolating enterovirus and poliovirus isolated in patients with acute flaccid paralytic syndrome in 2005

Background: Paralysis has been eliminated in Vietnam in 2000. To maintain the achievement, Vietnam needs to have more than 90% of children under 1 age drinking 3 doses of OPV, controlling cases of acute flaccid paralysis and diagnosing for virology in laboratory to determine causes of the disease. Results of laboratory identifying Polio virus and enterovirus in patients with acute flaccid paralysis is evidence of successful in paralytic elimination annually in Vietnam.\r\n', u'Objectives: To of isolate polio virus and enterovirus in patients with acute flaccid paralysis suspected paralysis in 2005.\r\n', u'Subjects and methods: The study included 267 cases with acute flaccid paralysis from 29 provinces, cities in the North and six provinces in the Central of Vietnam during 2005.\r\n', u'Results:Results of surveillance for acute flaccid paralysis and indicators of samples tested in 2005 have reached the criteria regulated by the World Health Organization. 8 poliovirus strains and 56 other non-polio enterovirus strains were isolated from 538 stool specimens of above patients. All isolated poliovirus strains were confirmed as Sabin-like strains. 56 non-polio enterovirus strains included coxsaxkie A (3), conxsackieB (5), echoviruses (34), enterovirus 71 (1) and untyped enteroviruses (13). Wild polio virus was not isolated in 2005.\r\n', u'Conclusion: The result confirmed successfulness in maintaining of poliomyelitis free status in the North and 6 provinces of the Central of Vietnam in 2005.\r\n', u'\r\n', u'\r\n', u'

Enteroviruses isolated in patients with acute respiratory infections

Background: at present, some enterovirus also was considered causes of acute respiratory infections in children. In Vietnam, no studies were published on the enteroviruses causing acute respiratory infections in humans. The research results would contribute to control and prevention of respiratory tract infections. Objectives: to identify enteroviruses causing acute respiratory infection syndrome in children. Subjectives and Method: a descriptive, prospective study, virus isolation. 185 samples of patients with acute respiratory tract infections, collected from both private clinics and from Dak Lak provincial general hospital, in 2004. Cells: RD, Hep2, L20B, and Vero provided by the World Health Organization (WHO). Antisera for diagnosing enteroviruses, antisera for diagnosing adenoviruses: A1-A7. Results: the results showed that 10.8% were positive with enteroviruses. These isolated enteroviruses consist of 13 Coxsackievirus B, 1 Echovirus, 1 Poliosabin type 1, and 5 untyped Enteroviruses. The result also showed that 8.1% of isolated viruses were Adenoviruses. Enteroviruses isolated mainly in September, followed by in February and in July accounted for 60% of isolated viruses. Conclusions: enteroviruses may be one of causes of respiratory infections in children. Some viruses had been isolated in the study such as: Coxsackievirus B, Echovirus, Poliosabin type 1, and untyped Enteroviruses.