A fed-batch fermentation process for poly (3-hydroxybutyrate-co-3-hydroxyvalerate) production by Yangia sp. ND199 using molasses as substrate

A locally isolated halophilic bacterium, Yangia sp. ND199 was able to use molasses as substrate for copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] production. Cell dry weight (CDW) of 6.37 g/l, P(3HB-co-3HV) content of 43.1 wt% and P(3HB-co-3HV) concentration of 2.75 g/l were obtained by Yangia sp. after 60 h of cultivation in flask. In a batch cultivation mode in a fermentor, the CDW was increased to 9.1 g/l but P(3HB-co-3HV) content was decreased to 37 wt%. Fed-batch fermentation with two different nutrient feeding strategies was used. High CDW of 54.8 g/l was obtained after 54 h of cultivation but P(3HB-co-3HV) content was still low (39.8 wt%). Two-step fed-batch fermentation with two different nutrient feeding strategies was then designed. High CDW of 50 g/l and P(3HB-co-3HV) content of 52.9 wt% were obtained after 54 h of cultivation. The two-step fed-batch process designed here for the production of P(3HB-co-3HV) by Yangia sp. ND199 can be developed and used for further studies

RECOVERY OF POLY(3-HYDROXYBUTYRATE) FROM Yangia sp. ND199 BY SIMPLE DIGESTION WITH SODIUM HYPOCHLORITE

Polyhydroxyalkanoate (PHA) is a biodegradable polymer synthesized intracellularly by many microorganisms. After extraction from the cells, they possess the common features of non-toxic, biocompatible, biodegradable and recyclable. These features render them highly competitive with polypropylene or other petroleum-derived plastics, especially in medicine. The isolation and purification of PHA from bacterial cells are the key step of PHA production process. There are several methods have been used for OHA purification, these include solvent extraction, enzymatic hydrolysis, and chemical digestion. In this study we used chemical digestion method for purification of PHB from Yangia sp. ND199. Among various chemical tested (NaOH, HCl, KOH, NaOCl, and SDS), NaOCl was found as an efficient chemical for PHB recovery and PHB purity from Yangia sp. ND199. The optimal purity and recovery conditions were a ratio of 1:1 (v/v, solution containing 100 g/l bacterial cells and solution containing 6% NaOCl), a 30 oC temperature and a 1 h treatment time. Under such conditions, a purity of 99% and a recovery of 94% were obtained. This method is sumple and can be developed and used for industrial scale

Investigating the Effect of Matrices and Densities on the Efficiency of HPGe Gamma Spectroscopy Using MCNP

When determining radioactivities in environmental samples using low-level gamma spectroscopy, in order to raise detection limit, voluminous samples are used. It takes in account for the self-absorption (self-attenuation) of gamma rays in samples. The self-absorption effect is small or large depend on the sample shapes, matrices and densities. In this paper, we investigated the effect of some regular matrices such as water, soil, epoxy resin on the detector efficiency. Some analytical formulas for the correction of matrix and densities for soil sample was established and applied to calculate some activities from standard sample of IAEA-375

In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO) to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells

TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

3D object retrieval is an important yet challenging task, which has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe that this task has the potential to drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from being fully solved. As such, we provide insights into potential areas for future research and improvements. We believe that we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies.Comment: arXiv admin note: text overlap with arXiv:2304.0573

Optimising diagnosis and treatment of tuberculosis infection in community and primary care settings in two urban provinces of Viet Nam: a cohort study

Objectives: To end tuberculosis (TB), the vast reservoir of 1.7–2.3 billion TB infections (TBIs) must be addressed, but achieving global TB preventive therapy (TPT) targets seems unlikely. This study assessed the feasibility of using interferon-γ release assays (IGRAs) at lower healthcare levels and the comparative performance of 3-month and 9-month daily TPT regimens (3HR/9H). Design, setting, participants and intervention: This cohort study was implemented in two provinces of Viet Nam from May 2019 to September 2020. Participants included household contacts (HHCs), vulnerable community members and healthcare workers (HCWs) recruited at community-based TB screening events or HHC investigations at primary care centres, who were followed up throughout TPT. Primary and secondary outcomes: We constructed TBI care cascades describing indeterminate and positivity rates to assess feasibility, and initiation and completion rates to assess performance. We fitted mixed-effects logistic and stratified Cox models to identify factors associated with IGRA positivity and loss to follow-up (LTFU). Results: Among 5837 participants, the indeterminate rate was 0.8%, and 30.7% were IGRA positive. TPT initiation and completion rates were 63.3% (3HR=61.2% vs 9H=63.6%; p=0.147) and 80.6% (3HR=85.7% vs 9H=80.0%; p=0.522), respectively. Being male (adjusted OR=1.51; 95% CI: 1.28 to 1.78; p<0.001), aged 45–59 years (1.30; 1.05 to 1.60; p=0.018) and exhibiting TB-related abnormalities on X-ray (2.23; 1.38 to 3.61; p=0.001) were associated with positive IGRA results. Risk of IGRA positivity was lower in periurban districts (0.55; 0.36 to 0.85; p=0.007), aged <15 years (0.18; 0.13 to 0.26; p<0.001), aged 15–29 years (0.56; 0.42 to 0.75; p<0.001) and HCWs (0.34; 0.24 to 0.48; p<0.001). The 3HR regimen (adjusted HR=3.83; 1.49 to 9.84; p=0.005) and HCWs (1.38; 1.25 to 1.53; p<0.001) showed higher hazards of LTFU. Conclusion: Providing IGRAs at lower healthcare levels is feasible and along with shorter regimens may expand access and uptake towards meeting TPT targets, but scale-up may require complementary advocacy and education for beneficiaries and providers

Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) Production by a Moderate Halophile Yangia sp ND199 Using Glycerol as a Carbon Source

Yangia sp. ND199, a moderate halophile isolated from mangrove soil sample in Vietnam, was found to accumulate poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from unrelated carbon sources in a medium with 4.5 % (w/v) NaCl. Cultivation with glycerol as carbon source and yeast extract as nitrogen source resulted in maximum cell dry weight of 5.7 g/l and PHBV content of 52.8 wt% (containing 2.9 mol% of 3HV) after 40 h. The 3HV content of the PHBV was the highest during initial stages of copolymer production and decreased with increase in the copolymer amount with time, but was not affected by changing the pH of the culture medium. Only homopolymer poly(3-hydroxybutyrate) was synthesized when monosodium glutamate was used as the nitrogen source. Fed-batch cultivation of Yangia sp. ND199 with glycerol and yeast extract gave PHBV content and productivity of 53.2 wt% and 0.44 g/l/h, respectively, which were reduced to 40.6 wt% and 0.25 g/l/h, respectively, with crude glycerol as carbon source. Both the copolymer content and productivity were improved to 56 wt% and 0.61 g/l/h, respectively, by using 1:1 mixture of crude glycerol and high fructose corn syrup. This is the first report of PHBV production by a wild-type halophilic bacterium using glycerol as carbon source