Simultaneous electrochemical determination of uric acid and hypoxanthine at a TiO2/graphene quantum dot-modified electrode.

A TiO2/graphene quantum dots composite (TiO2/GQDs) obtained by in situ synthesis of GQDs, derived from coffee grounds, and peroxo titanium complexes was used as electrode modifier in the simultaneous electrochemical determination of uric acid and hypoxanthine. The TiO2/GQDs material was characterized by photoluminescence, X-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray mapping. The TiO2/GQDs-GCE exhibits better electrochemical activity for uric acid and hypoxanthine than GQDs/GCE or TiO2/GCE in differential pulse voltammetry (DPV) measurements. Under optimized conditions, the calibration plots were linear in the range from 1.00 to 15.26 µM for both uric acid and hypoxanthine. The limits of detection of this method were 0.58 and 0.68 µM for uric acid and hypoxanthine, respectively. The proposed DPV method was employed to determine uric acid and hypoxanthine in urine samples with acceptable recovery rates.

Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots.

A simple approach was developed to synthesize cobalt ferrite nanoparticles/graphene quantum dots (CF/GQDs). The material was prepared from a homogeneous mixture of iron nitrate, cobalt nitrate, and starch at 140, 180 and 200 °C in a 24 h thermal hydrolysis process. The obtained materials were characterised by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence spectroscopy, vibrating-sample magnetometry, and nitrogen adsorption/desorption isotherms. Cobalt ferrite crystals of around 8-10 nm and graphene quantum dots formed directly at 200 °C. Stacking GQDs sheets onto the CF nanoparticles resulted in CF/GQDs nanoparticles. The nanocomposite exhibits satisfactory fluorescent and superparamagnetic properties, which are vital for catalytic applications. The CF/GQDs catalyse significantly the degradation of methylene blue (MB) under visible light. The catalyst can be recycled with an external magnetic field and displays suitable stability. Also, it was reused in three successive experiments with a loss of efficiency of about 5%. The CF/GQDs are considered as an efficient photocatalyst for MB degradation and other dyes.

Synergistic infection of Edwardsiella ictaluri and Flavobacterium oreochromis in cage cultured tilapia (Oreochromis sp.).

Widespread distribution of a highly pathogenic Edwardsiella ictaluri strain in farmed tilapia in northern Vietnam has recently been reported. The subsequent investigation noticed a disease outbreak occurred at five nearby tilapia farms with floating cages, in which the clinical signs of both edwardsiellosis and columnaris diseases were observed on the same infected fish and caused 65% to 85% fish mortality. Naturally diseased fish (n = 109) were sampled from the five infected farms for bacterial identification and conducting challenge tests. The two bacteria Edwardsiella ictaluri and Flavobacterium oreochromis were identified by a combination of biochemical tests, PCR and 16SrRNA sequencing methods. Experimental challenge tests on Nile tilapia resulted in the median lethal dose (LD50 ) of E. ictaluri and F. oreochromis at 70 CFU/fish by intraperitoneal (i.p.) injection and 3.6 × 106 CFU/mL by immersion, respectively. The experimentally co-infected challenged fish exposed to LD50 doses resulted in 83% ± 6% mortality, with the infected fish exhibiting clinical signs of both edwardsiellosis and columnaris diseases, mimicking the naturally diseased fish. This finding suggests that the co-infection of E. ictaluri and F. oreochromis may interact in a synergistic manner, to enhance the overall severity of the infection and elevates the need for efficient methods to control both pathogens.

First record of the genus Testudobracon Quicke, 1986 (Hymenoptera: Braconidae: Braconinae) in Vietnam, with description of four new species.

Five species of the genus Testudobracon Quicke, 1986 in Vietnam were recognized, and four new species, viz. Testudobracon alius Long, sp. nov., Testudobracon descensus Long, sp. nov., Testudobracon imitator Long, sp. nov., and Testudobracon phiaoacus Long & PQMai, sp. nov. are described and fully illustrated. Additionally, the genus Testudobracon and one species, Testudobracon flavus Tang, Chen & He, 1997, are newly recorded for the Vietnam's braconid fauna. A checklist of the already known of Testudobracon species is provided, a key to Vietnamese species of the genus Testudobracon in Vietnam, their in-country distribution, and differentiation of the known similar species are also given.

Four new species of the subfamily Braconinae (Hymenoptera: Braconidae) from Vietnam.

This paper contains descriptions and illustrations of four new species of braconine wasps from two genera Megalommum Szpligeti, 1900 and Nedinoschiza Cameron, 1911 from Vietnam, viz. Megalommum hoabinhense Long, sp. nov., M. simulatum Long, sp. nov., M. sonlaense Long, sp. nov. and Nedinoschiza khuathalinhae Long, sp. nov. Additionally, the genus Megalommum is the first record for Vietnam.

Electrochemical sensor to detect terbutaline in biological samples by a green agent.

In this research, reduced graphene oxide (RGO) which is a form of graphene oxide (GO) was formed through a reduction process using a "green agent" called Ascorbic acid (AA). RGO was then modified on the surface of the glassy carbon electrode (GCE) to generate RGO/GCE (an advanced electrode). The RGO/GCE was then used to detect Terbutaline (TB) in urine samples of volunteer athletes (n = 5) using well-known spectrophotometric analyses including X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible Spectroscopy (UV-Vis), and Raman and electrochemical methods using voltammetric analyses such as differential pulse anodic stripping voltammetry (DP-ASV) and cyclic voltammetry (CV). Comparing various analysis methods using RGO/GCE to detect TB in human urine samples, voltammetric analysis specifically DP-ASV demonstrated higher sensitivity and selectivity in detecting TB than spectrophotometric analyses. Thus, in this study, several factors that would affect the voltammetric signals such as pH and interferents were evaluated and the electroactive surface area was also calculated. Our findings indicated that the RGO/GCE showed excellent repeatability, reproducibility, and long-term stability suggesting that TB could be detected more effectively using RGO/GCE than bare GCE. The detection limit of 0.0052 µM achieved in this study indicated that RGO/GCE can effectively detect TB in human urine while demonstrating reasonable selectivity and sensitivity.

Six new braconid wasps of the genus Colastomion Baker, 1917 (Hymenoptera: Braconidae: Rogadinae) from Vietnam.

The relatively small genus Colastomion Baker, 1917 is newly recorded for Vietnams braconid fauna and six new species are described and fully illustrated, viz. Colastomion asperum Long, sp. n; Colastomion cephonodes Long PVLam, sp. n.; Colastomion citrum Long, sp. n.; Colastomion neuterum Long, sp. n.; Colastomion nigroconfusum Long Pham, sp. n. and Colastomion vietnamenese Long, sp. n. Based on both females and males, a key to the new species from Vietnam is given. Diagnostic characters of the new species are also analyzed and compared with other Colastomion species from the Oriental region. Additionally, the first host record for the new species, C. cephonodes sp. n., is provided as this new species is reared from caterpillars of the coffee hawkmoth, Cephonodes hylas (Linnaeus, 1771).

Two new species of the genus Austerocardiochiles Dangerfield, Austin amp; Whitfield, 1999 (Hymenoptera: Braconidae: Cardiochilinae) from Vietnam.

Two new species of the genus Austerocardiochiles Dangerfield, Austin Whitfield, 1999 from Vietnam, viz. A. mellosus Long, sp. n. and A. simulatus Long, sp. n., are described and illustrated. Additionally, the genus Austerocardiochiles is newly recorded for the braconid fauna of Vietnam. The checklist and distribution of already known species of the genus Austerocardiochiles are given. A comprehensive key to Austerocardiochiles species from Oriental region is also provided.

New record of the genus Zombrus Marshall, 1897 (Hymenoptera: Braconidae: Doryctinae), with description of three new species from Vietnam.

The genus Zombrus Marshall, 1897, is newly recorded for Vietnam with four species. Three new species (Z. bicoloricorpus Long, sp. n., Z. flavicorpus Long van Achterberg, sp. n., and Z. tricoloricorpus Long, sp. n.) are described and illustrated, and one species (Z. pallidiventris Cameron, 1910) is reported for the first time from Vietnam and outside Indonesia. The key to Oriental and Palaearctic species of Zombrus and a checklist with distributions of the nine species from Oriental and Palaearctic regions are provided.

Interview-based sighting histories can inform regional conservation prioritization for highly threatened cryptic species.

The use of robust ecological data to make evidence-based management decisions is frequently prevented by limited data quantity or quality, and local ecological knowledge (LEK) is increasingly seen as an important source of information for conservation. However, there has been little assessment of LEK's usefulness for informing prioritization and management of landscapes for threatened species, or assessing comparative species status across landscapes.A large-scale interview survey in the Annamite Mountains (Vietnam and Lao PDR) compiled the first systematic LEK data set for saola Pseudoryx nghetinhensis, one of the world's rarest mammals, and eight other ungulates. Saola conservation is hindered by uncertainty over continued presence across much of its proposed distribution. We analysed comparative LEK-based last-sighting data across three landscapes to determine whether regional sighting histories support previous suggestions of landscape importance for saola conservation (Hue-Quang Nam: top-priority Vietnamese landscape; Pu Mat: lower priority Vietnamese landscape; Viengthong: high-priority Lao landscape) and whether they constitute an effective spatial prioritization tool for cryptic species management.Wild pig and red muntjac may be the only Annamite ungulates with stable populations; the regional status of all other species appears to be worse. Saola have declined more severely and/or are significantly rarer than most other ungulates and have been seen by relatively few respondents. Saola were also frequently considered locally rarest or declining, and never as species that had not declined.In contrast to other species, there are no regional differences in saola sighting histories, with continued persistence in all landscapes challenging suggestions that regional status differs greatly. Remnant populations persist in Vietnam despite heavy hunting, but even remote landscapes in Lao may be under intense pressure.Synthesis and applications. Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species. Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species.