In this work, monodisperse β-NaLuF4:Yb,Er microcrystals with intense upconversion emission were synthesized via a modified hydrothermal method. With the increase of reactant concentration, their ...production yield is increased obviously, and the upconversion emission intensity in β-NaLuF4:Yb,Er microcrystals is also enhanced significantly. The luminescence enhancement should be attributed to minimal internal OH− defects, validated by a combination of analytical X-ray diffraction (XRD), energy dispersive spectrum (EDS), and Eu3+ structural probe measurements. We also reveal that high Na+:RE3+ ratio in the β-NaLuF4:Yb,Er microcrystals prepared under Na+-rich reaction will arouse the increased repulsive energy of β-NaLuF4 microcrystals between F− and OH− anions and then facilitate the substitution of large OH− ions by small F− ions under F−-rich reaction conditions. Minimal OH− concentrations can limit nonradiative relaxation and promote excitation energy harvesting for high upconversion efficiency. The presented results not only offer a facile method for the simultaneous production yield and luminescence intensity increase of β-NaREF4 microcrystals, but also uncover a better insight into the upconversion emission alterations, which is favorable to broaden their practical applications.
Internal OH− defects can be greatly reduced with the increase of the reactant concentration, which facilitate the excitation energy harvesting for remarkably enhanced upconversion luminescence. Display omitted
•β-NaLuF4:Yb,Er microcrystals were successfully synthesized under different reactant concentration via a hydrothermal method.•The production yield is increased obviously, and the upconversion emission intensity is also enhanced significantly.•The enhanced upconversion emission should be mainly ascribed to minimal internal OH− defects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
China is the largest producer and exporter of royal jelly (RJ) in the world, supplying >90% of the global market. The high production of RJ in China is principally owing to the high RJ-producing ...lineage of honeybees (Apis mellifera ligustica Spinola, 1806) established by beekeepers in the 1980s. We describe the development of high royal jelly-producing honeybees and the management of this lineage today. Previous research and recent advances in the genetic characterization of this lineage, and the molecular markers and mechanisms associated with high RJ production are summarized. The gaps in our knowledge and prospects for future research are also highlighted.
In January 2023, Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oil flow of over 100 cubic meters from the Jurassic channel sandstone for the first time, realizing a ...major breakthrough. In order to provide more support for further oil and gas exploration in this area, this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong region of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF. Then, oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed. Finally, the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition, lateral migration, thin reservoir and strong heterogeneity are researched and developed, and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out. And the following research results are obtained. First, in the second member of Lianggaoshan Formation (“Liang 2 Member” for short) in Bazhong region, multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%. The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores, the pore throat structure is good, and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel. Second, the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir, whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members. Third, channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 and Liang 3 Members, and the source-reservoir configuration is good, with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment. Fourth, for the channel sandstones with multi-stage vertical superimposition, lateral migration, thin reservoir and strong heterogeneity, the reservoir prediction technology of “high-frequency sequence stratigraphy slice, seismic frequency decomposition and facies-constrained seismic waveform indication inversion” is developed to precisely characterize the “sweet spot” target of narrow channel sandstone, and the key fracturing technology of “dense cutting + composite temporary plugging + high-intensity proppant injection + imbibition and oil-increasing” is formed to realize the large-scale reconstruction of channel sandstone reservoir. In conclusion, the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong region reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin, and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
High-yielding industrial
Streptomyces
producer is usually obtained by multiple rounds of random mutagenesis and screening. These strains have great potential to be developed as the versatile chassis ...for the discovery and titer improvement of desired heterologous products. Here, the industrial strain
Streptomyces rimosus
461, which is a high producer of oxytetracycline, has been engineered as a robust host for heterologous expression of chlortetracycline (CTC) biosynthetic gene cluster. First, the industrial chassis strain SR0 was constructed by deleting the whole oxytetracycline gene cluster of
S. rimosus
461. Then, the biosynthetic gene cluster
ctc
of
Streptomyces aureofaciens
ATCC 10762 was integrated into the chromosome of SR0. With an additional constitutively expressed cluster-situated activator gene
ctcB
, the CTC titer of the engineering strain SRC1 immediately reached 1.51 g/L in shaking flask. Then, the CTC titers were upgraded to 2.15 and 3.27 g/L, respectively, in the engineering strains SRC2 and SRC3 with the enhanced
ctcB
expression. Further, two cluster-situated resistance genes were co-overexpressed with
ctcB
. The resultant strain produced CTC up to 3.80 g/L in shaking flask fermentation, which represents 38 times increase in comparison with that of the original producer. Overall, SR0 presented in this study have great potential to be used for heterologous production of tetracyclines and other type II polyketides.
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CEKLJ, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Chlorothricin (CHL), produced by
Streptomyces antibioticus
DSM 40725 (wild-type strain, WT), belongs to a growing family of spirotetronate antibiotics that have biological activities inhibiting ...pyruvate carboxylase and malate dehydrogenase. ChlF2, a cluster-situated SARP regulator, can activate the transcription of
chlJ
,
chlC3
,
chlC6
,
chlE1
,
chlM
, and
chlL
to control CHL biosynthesis. Co-expression of
chlF2
and
chlK
encoding type II thioesterase in WT strain under the control of P
kan
led to high production of chlorothricin by 840% in comparison with that of WT. Since the inhibitory activity of CHL against several Gram-positive bacteria is higher than des-CHL, combinatorial strategies were applied to promote the conversion of des-CHL to CHL. Over-expression of
chlB4
, encoding a halogenase, combining with the supplementation of sodium chloride led to further 41% increase of CHL production compared to that of F2OE, a
chlF2
over-expression strain. These findings provide new insights into the fine-tuned regulation of spirotetronate family of antibiotics and the construction of high-yield engineered strains.
Sucrose is the predominant form of sugar transported from photosynthetic (source) to non-photosynthetic (sink) organs in higher plants relying on the transporting function of sucrose transporters ...(SUTs or SUCs). Many SUTs have been identified and characterized in both monocots and dicots. However, the function of sucrose transporters (SUTs or SUCs) from
is not clear. As the world's most planted grape species,
owns three sucrose transport activity verified SUTs. In this study, we constructed three kinds of
-overexpressing transgenic Arabidopsis.
-overexpressing transgenic Arabidopsis was cultured on sucrose-supplemented medium.
- and
-overexpressing lines had similar thrived growth phenotypes, whereas the size and number of leaves and roots from
-overexpressing lines were reduced compared with that of WT. When plants were cultured in soil, all SUT transgenic seedlings produced more number of leaves and siliques, resulting in higher yield (38.6% for
-transformants) than that of WT. Besides,
-transformants and
-transformants enhanced drought resistance in Arabidopsis, providing a promising target for crop improvement.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of ...water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background: Launched by the U.S. Environmental Protection Agency (EPA) in 1998, the High Production Volume (HPV) Challenge Program was developed to address the perceived gap in basic hazard ...information for the 2,800 chemicals produced or imported into the United States in quantities of ≥ 1 million pounds per year. Health and environmental effects data obtained from either existing information or through new vertebrate animal testing were voluntarily submitted by chemical companies (sponsors) to the U.S. EPA. Despite the potential for extensive animal testing, animal welfare guidelines were not provided until after the start of the program. Objectives: We evaluated compliance with the animal welfare principles that arose from an agreement reached between the U.S. EPA and animal protection organizations and tracked the HPV program's use of animals for testing. Discussion: Under a worst-case scenario, the HPV program had the potential to consume 3.5 million animals in new testing. After application of animal-saving measures, approximately 127,000 were actually used. Categorization of chemicals based on similar structure—activity and application of read-across, along with use of existing test data, were the most effective means of reducing animal testing. However, animal-saving measures were inconsistently used by both sponsors and the U.S. EPA. Conclusions: Lessons learned from the HPV program can be applied to future programs to minimize animal testing and promote more human-relevant chemical risk assessment.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
The European chemical control regulation (REACH) requires that data on physical/chemical, toxicological and environmental hazards be compiled. Additionally, REACH requires formal assessments to ...ensure that substances can be safely used for their intended purposes. For health hazard assessments, reference values (Derived No Effect levels, DNELs) are calculated from toxicology data and compared to estimated exposure levels. If the ratio of the predicted exposure level to the DNEL, i.e. the Risk Characterization Ratio (RCR), is less than 1, the risk is considered controlled; otherwise, additional Risk Management Measures (RMM) must be applied. These requirements pose particular challenges for complex substances. Herein, “white spirit”, a complex hydrocarbon solvent, is used as an example to illustrate how these procedures were applied. Hydrocarbon solvents were divided into categories of similar substances. Representative substances were identified for DNEL determinations. Adjustment factors were applied to the no effect levels to calculate the DNELs. Exposure assessments utilized a standardized set of generic exposure scenarios (GES) which incorporated exposure predictions for solvent handling activities. Computer-based tools were developed to automate RCR calculations and identify appropriate RMMs, allowing consistent communications to users via safety data sheets.
•Preparation of generic but comprehensive hazard assessment profiles for use in REACH DNEL calculations.•Estimation of potential exposures for solvent use.•Definition of criteria by which to group similar applications.•Exposure reduction measures for potential risks identified.•Utilization of effective methods to compile information to facilitate risk communication.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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