Atmospheric Temperature Research Articles

Variations in deep-sea methane seepage linked to millennial-scale changes in bottom water temperatures ~ 50–6 ka, NW Svalbard margin

During the last glaciation, the northern hemisphere experienced profound millennial-scale changes (termed Dansgaard-Oeschger (DO) events) in atmospheric and oceanic temperatures. In the North Atlantic, the fluctuations resulted in extremely unstable bottom water conditions with bottom water temperatures (BWT) varying up to > 5 °C. We have studied these changes in a core from 1,300 m water depth at Vestnesa Ridge, northwestern Svalbard margin to investigate a possible connection between BWT and seepage of methane from the seafloor covering the period ~ 50–6 ka. Beneath Vestnesa Ridge, gas hydrates containing vast amounts of methane are kept stable due to the high pressure and low temperatures. Release of gas is shown by numerous pockmarks on the seafloor. The pockmarks at 1,300 m water depth are presently inactive, but they bear witness of earlier activity. Our study shows that from ~ 50–6 ka, the core site experienced repeated increases in BWT and in the emissions of gas, both following the pattern of the DO events. This correspondence in time scale indicates that BWT was the primary forcing factor for the variability in methane release. However, the releases were delayed by up to > 1,000 years compared to the initial increase in BWT.

Correlation between Peak Height of Polar Mesospheric Clouds and Mesopause Temperature

Polar mesospheric clouds (PMCs) are ice crystal clouds formed in the mesosphere of high-latitude regions in both the northern (NH) and southern hemispheres (SH). Peak height is an important physical characteristic of PMCs. Satellite observation data from solar occultation for ice experiments (SOFIE) during seven PMC seasons from 2007 to 2014 show that the difference between the height of the mesopause and the peak height of the PMCs (Zmes-Zmax) were inversely correlated with the atmospheric mesopause temperature. The Zmes-Zmax averages for all seasons for the NH and SH were 3.54 km and 2.66 km, respectively. They were smaller at the starting and ending stages of each PMC season and larger in the middle stages. Analysis of the individual cases and statistical results simulated by the PMCs 0-D model also revealed the inverse correlations between the Zmes-Zmax and mesopause temperature, with correlation coefficients of −0.71 and −0.62 for the NH and SH, respectively. The corresponding rates of change of Zmes-Zmax with respect to mesopause temperature were found to be −0.21 km/K and −0.14 km/K, respectively. The formation mechanism of PMCs suggests that a lower temperature around the mesopause can lead to a greater distance and longer time for ice crystals to condense and grow in clouds. Thus, ice crystals sediment to a lower height, making the peak height of the PMCs further away from the mesopause. In addition, disturbances in small-scale dynamic processes tend to weaken the impact of temperature on the peak height of PMCs.

Breeding of L-tryptophan high-yield strain by ARTP mutagenesis and high-throughput screening

L-tryptophan is an indispensable essential amino acid with a wide range of applications, which leads to a high demand. Accordingly, the production of L-tryptophan becomes a much-anticipated direction in research and industrial development. While irrational mutagenesis is an effective means to breed industrial strains, how to screen the strains with desirable phenotypes is still a major challenge. In order to improve the efficiency and accuracy of screening L-tryptophan high-yield strains, we used atmospheric and room temperature plasma mutagenesis to construct a random mutant library and then combined it with high-throughput screening in deep-well plates. Using a pseudo-fluorescent protein sensor capable of responding specifically to L-tryptophan, we successfully screened out a strain producing L-tryptophan at a high yield from a random mutagenesis library. The fermentation with the strain in shake flasks produced L-tryptophan at a yield of 1.99 g/L, which was 41.77% higher than that of the starting strain. Finally, the mechanism of high yield of the strain was deciphered by comparative genomics and transcriptomics. The above strategies provide a solid research foundation for further selection and development of high quality L-tryptophan producing strains.

Enhanced production, artificial intelligence optimized three-phase partitioning extraction, and in silico characterization of extracellular neutral Bacillus cereus proteinase

The present study applied atmospheric and room temperature plasma (ARTP) mutagenesis to improve Bacillus cereus strain for neutral proteinase production. The selected improved stable strain, Phe−Tyr-ARTP-60-E demonstrated a 2.88-fold enhanced proteinase yield and 2.81-fold enhanced proteinase activity with shortened fermentation time. An artificial neural network-embedded genetic algorithm (ANN-GA) was employed to optimize the enzyme's three-phase partitioning (TPP) recovery using Python software. The optimized solution of the hybrid model recommended 38.05% wv−1 (NH4)2SO4, 1.0:2.0 crude extract/tert-butanol ratio, pH 5.84 at 23.4 °C, for the exclusive partitioning of proteinase in the intermediate phase, with 202% recovery, 13-fold purity with specific activity of 922 Umg−1. Sensitivity analysis of the model revealed that enzyme recovery was most sensitive to crude extract/tert-butanol ratio with total sensitivity (ST) of 0.253 while purification factor was most sensitive to pH with an ST of 0.444. In silico analysis using Expasy ProtParam tool revealed that mutant proteinase had 3 amino acid substitutions; Val-to-Cys; Val-to-His and Ile-to-Lys, at positions 152, 288, and 292, respectively, and 39.2 kDa molecular weight, 6.42 isoelectric point, and 33.35 instability index. The 3-Dimensional structure of the enzyme predicted by ModWeb v r273 Server revealed 39% sequence identity with Pseudoalteromonas lipolytica thermolysin. The macromolecule increased transmittance in lysozyme-coated contact lenses by 99.6% in 45 min. We conclude that ARTP mutagenesis and ANN-GA optimized TPP are effective and efficient recalcitrant strain improvement and product recovery methods, respectively. Further genetic tools and analysis of the neutral proteinase-producing gene may be required for increased improvement toward sustainable application.

Mutagenesis selection and large-scale cultivation of non-green Chlamydomonas reinhardtii for food applications.

The green alga Chlamydomonas reinhardtii is an accepted food ingredient in the United States of America (United States), the European Union, Singapore, and China. It can be consumed in unlimited quantities. As this alga is rich in nutrients, proteins, and rough polysaccharides and contains a balanced proportion of various amino acids, it is an excellent raw material for food production. Although various edible brown and green algae are available on the market, their color and strong grassy flavor have constrained their popularity among consumers, thereby limiting their application in food additives and animal feed. Chlorophyll-deficient C. reinhardtii mutants were developed using atmospheric and room temperature plasma (ARTP) technology. A yellow-colored C. reinhardtii variant (A7S80) cultivated in dark conditions was isolated. This light-sensitive variant has a mutation in the chlM gene, and it can grow heterotrophically using acetate as a carbon source. Compared to wild-type C. reinhardtii, A7S80 has significantly lower chlorophyll levels, reduced grassy flavor, and more diverse pigments, with considerable potential for commercial application in human and animal food production, as well as in pharmaceutical and cosmetic industries.

Simulated warming reduced greenhouse gas emissions by lowering soil moisture in a Pinus tabulaeformis forest of the temperate zone

The forest soil carbon represents the largest carbon pool in the terrestrial ecosystem. To clarify the effect of climate warming on the soil carbon pool of a Pinus tabulaeformis plantation in the northern temperate zone, an Open-Top Chamber was used to study the effects of warming on soil temperature and moisture, soil enzyme activity, soil active organic carbon, and greenhouse gas emissions in different soil layers. The results showed that (1) warming increased the temperature and decreased the moisture content of the atmosphere and soil. Atmospheric temperature increased by 0.9°C on average, and atmospheric moisture decreased by 0.05%. (2) Warming had no significant effect on soil active organic carbon or enzyme activity, but had a significant effect on the active organic carbon content and enzyme activity in individual soil layers in individual months. (3) Warming reduced soil CO2 emissions from the control treatment, from 996.35 to 781.57 g·m−2. The soil of the P. tabulaeformis forest in Daqing Mountain is a sink of atmospheric CH4. Therefore, after the short-term warming treatment, the soil moisture was reduced; greenhouse gas emissions were significantly reduced, and the warming formed a negative feedback with soil greenhouse gas flux.

NUMERICAL MODELLING OF RADIATOR SYSTEM PERFORMANCE UNDER BAUCHI CLIMATIC CONDITIONS

The cooling system of the car plays a crucial role in managing the excess heat generated by the engine during its operation. Among its components, the radiator is pivotal for efficiently dissipating heat. However, the effectiveness of a radiator is influenced by various factors, including external conditions such as atmospheric temperature, humidity, and wind speed. This research aimed to understand the impact of Bauchi climatic conditions on automotive radiators. A comprehensive approach was employed, utilizing reverse engineering techniques to create a detailed model of a car radiator using SolidWorks, a computer-aided design (CAD) software. This model underwent simulations using ANSYS software with water as the coolant fluid. Environmental temperature, humidity, and wind speed data for Bauchi North and Bauchi South were sourced from the Nigerian Meteorological Agency (NiMet). The simulation timeframe spanned from January to December. The study shows the effects of environmental temperature, humidity, and wind speed on radiator performance. The highest outlet temperature recorded was 43.50°C at a flow rate of 2500 kg/h in April, and the lowest outlet temperature was 40.01°C at a flow rate of 500 kg/h in Bauchi North. For Bauchi South, the highest outlet temperature was 40.98°C at a flow rate of 2500 kg/h in April, and the lowest was 37.12°C at a flow rate of 500 kg/h. This study highlights the pivotal role of Bauchi's atmospheric conditions in influencing radiator performance, emphasizing the interplay between environmental factors and engineering design in automotive cooling systems.

Enhancing outdoor comfort in urban hot climates: investigating the cooling impact of two tropical trees through shade provision and transpiration

ABSTRACT One key ecosystem service widely known and attributed to trees in the urban environment is their ability to provide shade through their canopies and undertake evapotranspiration cooling. These in turn contribute to reduced atmospheric temperatures. A lesser-known aspect with little quantitative data is the heterogeneous temperature environment beneath the canopies at pedestrian or street level where the cooling will benefit thermal comfort. This study was conducted throughout 2022. It collected data where air temperature was measured under the canopies of two urban tropical tree species, Samanea saman and Peltophotum pterocarpum, at three different heights, which were 1, 3 and 5 m, respectively, from the ground. This was to investigate whether crown architectures and the associated shade and cooling effects via transpiration can have a significant change in the surrounding temperature. The study observed surface and air temperatures coupled with meteorological data across cool, warm, and hot periods of the year. It was observed that soil temperature increased alongside increases in atmospheric temperatures with a more significant rise observed for P. pterocarpum despite the observation of greater wind speeds for both night and day at the site where this species was situated. The soil moisture potential data indicated the reverse where S. saman showed more negative values with the greatest increase under warm conditions. Interestingly, sap flow rates also indicated that P. pterocarpum had more efficient rates whether conditions were cool, warm, or hot, suggestive of more active transpirational cooling. This was despite a lower leaf area index, smaller crown volume and sap wood area for this species. Relationship analyses between sap flow and air temperatures at different heights under the canopies showed a positive correlation. This demonstrates that apart from shade provided by the canopies, transpiration is also an important parameter for cooling. The mean daytime air temperature indicated that the greatest cooling effect was experienced at the lowest level from the ground (at 1 m), and this was consistent for both species across cool, warm, and hot conditions with a significant cooling effect of between 2.3 and 4°C. Temperature data under the canopy (1 to 5 m from the ground) compared to the air temperature of the grass that was shaded indicated temperature differences of between 2.3 and 7.9°C at 5 m and between 1.9 and 5.6°C at 1 m (for both species) with a bigger reduction attributed to S. saman.

Experimental study of heat pipe start-up characteristics and development of an enhanced model considering gas diffusion effects

Heat pipe-based cooling reactors, offering passive heat transfer and modularity, are becoming the preferred type for micro-reactors. Alkali metals such as sodium, potassium and lithium are usually used as the working medium of the heat pipe, which is in a frozen state at normal atmospheric temperature. After heating the heat pipe, the working medium will melt and enter the gas chamber, and its flow state will undergo a transition from discontinuous flow to continuous flow. The start-up of the heat pipe affects the heat export and neutron physical characteristics of the heat pipe cooling reactor. Building a model of heat pipe can predict the start-up of heat pipe effectively, which can be helpful to study the start-up and safety analysis of heat pipe cooling reactor. In this paper, a heat pipe flat-front model considering the gas diffusion effect is established, and the gas temperature distribution characteristics in the non-continuous flow region are obtained through the start-up experiment of heat pipe. The calculated results of the flat-front model considering gas diffusion effect and the vertical flat-front model are compared with the experiment. The results show that the model in this paper can better describe the start-up of heat pipe. At the same time, the evaporation and condensation coefficient model based on temperature change is used to deal with the evaporation and condensation mass flow at the phase change interface of the heat pipe, which can better describe the temperature difference at the interface of the heat pipe.

Hysteresis in Water Content of Ultrafine Glassy Organic Aerosol Particles

AbstractWater content of aerosol particles is atmospherically important. Water content of organic aerosol (OA) particles has been estimated by assuming thermodynamic equilibrium. Here, we discovered that the hysteresis phenomenon occurred to water content of glassy ultrafine OA particles, demonstrating that thermodynamically non‐equilibrium states need to be considered. Hygroscopic growth for monodisperse ultrafine particles (sucrose and glucose) was investigated for the temperature range from 252 to 296 K. Hysteresis was not observable at 296 K, consistent with literature data. However, hysteresis in water content was observed at sub‐273 K. The lowest relative humidity (RH), at which hygroscopic growth of particles did not depend on exposure history to water vapor, was defined as threshold RH. Threshold RH for 100 nm particles was approximately the same as the glass transition points when hysteresis clearly happened, demonstrating that water diffusion in a highly viscous matrix of organic aerosols was the key to the phenomenon. Employment of a kinetic multi‐layer model quantitatively predicted threshold RH as a function of temperature, exposure time, and the particle size. Considering the temperature and RH range of Earth's atmosphere, we hypothesize that hysteresis in water content for organic aerosols ubiquitously occurs in the upper troposphere, impacting chemical aging and cloud formation processes.

Synthesis, antimicrobial activity, molecular docking and MD simulation studies, in silico ADME investigations and thermo-acoustic studies of heterocyclic dihydropyrimidine substituted 1,3,4-thiadiazole scaffolds

The connections between the chemical structures and antibacterial properties of different functional groups including organic molecules were examined in this study. we have synthesized a novel series of 1,3,4-thiadiazole hybrids (5a-o) based on 3,4-dihydropyrimidines. After an effective synthesis, the compounds' structure was confirmed by using spectrum techniques like IR, 1H NMR, 13C NMR, and mass spectrometry. Elemental analyses were performed on a Perkin-Elmer 2400 CHN analyzer and the resulting data were within the accepted range (± 0.40) of the calculated values. The in vitro antimicrobial activity of the compounds against a range of bacterial and fungal species. Compound 5i showed potent inhibitory effects against P. aeruginosa with MIC values of 12.5 μg/ml S. aureus and A.niger were positively affected by compound 5k with MIC values of 12.5 μg/ml and 50 μg/ml, respectively. Based on the results, compounds 5a and 5o have moderate activity against C.albicans and E. coli with MIC values of 50 μg/ml and 62.5 μg/ml respectively. Furthermore, molecular docking and molecular dynamics simulations were used to identify the most stable conformation of newly discovered inhibitors. Thermo-acoustical properties of derivatives 5k and 5l in DMSO and DMF solvent have been determined at three different atmospheric pressure temperatures (298.15, 308.15, and 318.15)K. The components of the liquid mixture's molecular interactions have been taken into account to explain these results. The acquired results are interpreted in terms of interactions between solutes and solvents, providing insight into the compounds' potential to form or disrupt structures in DMSO and DMF solutions.

Assessing the Tropospheric Impacts on Positioning Accuracy Using IGS02 Real-Time Service Data Versus Long-Convergence Static PPP in Gwagwalada, Abuja, Nigeria

Abstract: The International Association of Geodesy (IAG) has established the International GNSS Service-Real Time Service (IGS-RTS) as a service provider, offering real-time access to precise products like orbits, clock corrections, and code biases regarding satellite navigation and positioning system. These products serve as an alternative to ultra-rapid products in real-time applications. The performance of these products is assessed through daily statistics from Analysis Centres, which compare them to IGS rapid products. However, the accuracy of GPS real-time corrections for satellites during eclipsing periods was slightly reduced, attributed to the impact of environmental factors on the services. The speed of GNSS signals can be impacted by various atmospheric factors, including troposphere, temperature, pressure, and humidity, resulting in positioning inaccuracies and even giving rooms for signal jamming and hijacking. However, the unique weather conditions prevalent in the African continent are often overlooked during the development of error mitigation parameters and algorithms, which can lead to reduced accuracy in GNSS positioning in a region like Nigeria. The purpose of this study is to estimate the tropospheric impact on positioning with IGS02 Real Time Service data compared to long convergence Static-PPP in Gwagwalada Area Council, Abuja, Nigeria. The study adopts the determination of the GNSS Static observations (minimum of two hours per session) on the chosen stations as standard, determination of the IGS-RTS data observations using RTKLIB software; observations were done with IGS-RTS data stream of IGS02 and statistical tests were performed. The GNSS Static coordinates and IGS-RTS coordinates were validated from error due to troposphere, temperature, pressure, etc., with the computation of their mean horizontal and vertical uncertainties which have a similar level of accuracy but slightly differ at centimeter levels. The result shows the Root Mean Square (RMS) Error discrepancy of IGS02 at the Wet and Dry season, as compared with the Static-PPP was within 0.065(m) and 0.046(m) respectively.

OH radical initiated oxidative degradation of imidacloprid in the environment: An assessment of breakdown kinetics and environmental hazards

Imidacloprid (IMI) is a common neonicotinoid pesticide that acts via a similar mechanism of action to nicotine, a naturally occurring insecticide. It is therefore important to understand its chemical fate in the environment. Hydroxyl radicals (HO) are significant oxidizing species in natural aquifers due to their strong reactivity towards organic substrates. Therefore, principal photo-oxidation products are expected to form with the involvement of HO in the self-cleaning process of water in nature. Here quantum chemical calculations are used to examine the reaction of IMI with HO in the atmosphere and aqueous environments. It was found that the principal mechanism of the HO + IMI reaction is the hydrogen transfer that, in a two-step process, produces stable cations in the gas phase. Within the atmospheric temperature range of 253–323 K, the overall rate constants for the HO + IMI reaction decreased from 4.35 × 1010 to 2.13 × 1010 M−1 s−1. Consequently, IMI can undergo rapid gaseous degradation within a comparatively brief period of 2.81 × 10−4 – 5.75 × 10−4 years. However, differences in environmental temperature and pH in aqueous environments influence the processes, rate constants, and products of IMI breakdown by the HO radical. The data indicate that IMI breakdown by OH radicals is strongly temperature and pH-dependent, resulting in the generation of different reaction products. The results imply that at all pH levels, the interaction between IMI and the ambient HO radical in water produces toxic chemical species. According to the computed data, it appears that IMI and the vast majority of degradation products present potentially carcinogenic and/or mutagenic hazards, and they also lack downstream biodegradability.

Solid amine adsorbent with surfactant modification for Direct Air Capture (DAC) under different temperature and humidity conditions

Direct air capture (DAC) technologies have been vigorously pursued to achieve the goal of net-zero CO2 emissions due to the dramatic increase in atmosphere CO2 concentrations and global temperatures. In practical DAC conditions, variations in temperature and humidity can lead to different CO2 adsorption outcomes. Current studies lack comprehensive information on the optimal temperature and humidity conditions for DAC. In this study, a comparison between PMSU-F (impregnating polyethyleneimine (PEI600) on MSU-F support) and PPMSU-F (co-impregnating polyethylene glycol (PEG200) with PEI600 on MSU-F support) under different temperature and relative humidity conditions were conducted. Under dry conditions, the addition of PEG200 effectively enhanced the adsorption capacity, adsorption rate, and amine efficiency and decreased the energy consumption for desorption depending on the comparison of the two absorbents. Under the popular atmospheric temperature ranges (−5 °C–45 °C), an increase in temperature favors CO2 adsorption. Under humid conditions, the presence of PEG200 had a negative effect due to its strong hydrophilicity. By comparing dry and humid conditions, the introduction of moisture generally enhanced overall CO2 adsorption performance, and the adsorption capacity interestingly further increased under low-temperature conditions. The highest CO2 adsorbing capacity of PMSU-F (3.82 mmol/g) and PPMSU-F (3.76 mmol/g) appeared at −5 °C and 75% relative humidity, indicating that low temperature and relatively high relative humidity were more favorable for DAC, which is possibly attributed to the thermodynamic control under low temperatures with moisture. The results indicate that the adsorbents chosen in this study are promising for DAC under low temperatures and relatively high humidity conditions. The performances of modified DAC adsorbents, e.g., adsorption capacity, stability, antioxidant property for industrial-grade DAC system should be evaluated in the next work.

Influence of autumn soil moisture over Kalimantan Island on following winter precipitation over southern China

AbstractThe atmospheric activity on Kalimantan Island (KI) is important for regulating regional weather and climate. This study investigates the effect of autumn soil moisture over KI on following winter precipitation over southern China (SC) during 1968–2014. The results show that the autumn soil moisture over the KI has a significant negative correlation with subsequent winter precipitation over SC. The correlation remains statistically significant when using partial correlation to filter out the concurrent influences of El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) signals. The soil moisture anomalies over KI, which initiate in the autumn and persist into the winter, lead to changes in local thermal conditions and atmospheric temperature. Negative soil moisture anomalies over KI will result in positive heating anomalies of the atmosphere above the land surface. This atmospheric heating causes ascending motion, which creates a semi‐closed vertical circulation from KI to the tropical northwest Pacific. This vertical circulation would strengthen the northwest Pacific anticyclone and weaken the East Asian winter monsoon (EAWM). Consequently, southwesterly water vapour flux prevails in the SC as well as the South China Sea (SCS), facilitating the transportation of more water vapour into the SC. Simultaneously, water vapour convergence in the SC. Collectively, these contribute to an addition of precipitation over SC.

CO2 capture using red mud & mechanically-activated red mud and its kinetics under ambient conditions

Greenhouse gas emissions and the growing stockpiles of red mud, an alkaline industrial waste with potential for CO2 sequestration, present significant environmental challenges. This article aims to enhance the CO2 sequestration capacity of red mud by mechanically activating its surface using a high-energy planetary ball mill for extended grinding periods. The novelty of the study lies in investigating the CO2 sequestration capacity and evaluating its kinetics includingadsorption and desorption on feed and mechanically-activated red mud under atmospheric temperature and pressure for the first time via a direct gas–solid carbonation route using a fixed bed column. The effect of ball size (10,8 and 6 mm) used in high-energy planetary ball mills while mechanical activation, CO2 flow rate (20–80 ml/min), and reaction time (1–5 h) on the CO2 capture has been studied. Apart from this, experimental data on CO2 sequestered (1–5 h) and the extent of CO2 desorption (7–35 days) are fitted to various kinetic models, including pseudo-first-order, pseudo-second-order, and Avrami’s fractional order models. Results showed that the CO2 sequestration capacity of feed red mud is 3.75 mg/g, while the capacity of mechanically-activated red mud increased to 18.28 mg/g, with an adsorption time of 5 h at ambient temperature and pressure. The most suitable fit is attained with Avrami’s fractional order model, suggesting that both physisorption and chemisorption contribute to enhancing the CO2 sequestration capacity of red mud. The mechanism for this process has also been proposed along with the suitable characterizations.

Atmosphere and sea surface temperature coupled data assimilation with enhanced use of SST-sensitive microwave radiances

Atmosphere and sea surface temperature coupled data assimilation with enhanced use of SST-sensitive microwave radiances

On atmospheric pressure and temperature correlation across various terrain types

Temperature (T), pressure (p), and density (ρ) are fundamental variables describing the atmospheric behavior. This study investigates the interdependence of these variables near Earth's surface in real-world conditions, by evaluating data from different European weather stations. It has been found that the correlation between pressure and temperature is strongly related to the dynamics of the PBL that facilitates a two-group classification. The first group includes all the stations in the plain or in the valley-floor and exhibits a weak correlation, R(p,T). 2D density plots representing hourly pressure against temperature have a distinctive triangular shape at these stations. Regardless of location, the upper boundary of this triangle consistently fits a linear equation with a constant slope and an intercept that scales with the average pressure of the station. This finding holds promising implications for enhancing the quality check of pressure and temperature data, enabling the identification of implausible measurements using a unified equation. In contrast, the second group includes stations with a strongly positive correlation R(p,T) and a more linear density plot; it includes all stations near a mountain-top. Their correlations exhibit identical features when compared to radiosounding data extracted at corresponding heights. The study concludes that: i) the first group of stations is significantly influenced by non-hydrostatic processes such as turbulence, friction and surface radiative heating/cooling in the PBL, resulting in weakly negative R(p,T) for shorter timescales that become null over longer durations; ii) the second group of stations has R(p,T) characteristics similar to the free atmosphere, predominantly regulated by hydrostatic balance and the advection of sensible heat.

Local neighborhood affects stem rehydration under drought: evidence from mixtures of European beech with two different conifers.

Mixed-species forests are, for multiple reasons, promising options for forest management in Central Europe. However, the extent to which interspecific competition affects tree hydrological processes is not clear. High-resolution dendrometers capture sub-daily variations in stem diameter; they can simultaneously monitor stem growth (irreversible changes in diameter) and water status (reversible changes) of individual trees. Using the information on water status, we aimed to assess potential effects of tree species mixture, expressed as local neighborhood identity, on night-time rehydration and water stress. We deployed 112 sensors in pure and mixed forest stands of European beech, Norway spruce, and Douglas fir on four sites in north-western Germany, measuring stem diameter in 10-minute intervals for a period of four years (2019-2022). In a mixture distribution model, we used environmental variables, namely soil matric potential, atmospheric vapor pressure deficit, temperature, precipitation, and neighborhood identity to explain night-time rehydration, measured as the daily minimum tree water deficit (TWDmin). TWDmin was used as a daily indicator of water stress and the daily occurrence of sufficient water supply, allowing for stem growth (potential growth). We found that species and neighborhood identity affected night-time rehydration, but the impacts varied depending on soil water availability. While there was no effect at high water availability, increasing drought revealed species-specific patterns. Beech improved night-time rehydration in mixture with Douglas fir, but not in mixture with spruce. Douglas fir however, only improved rehydration at a smaller share of beech in the neighborhood, while beech dominance tended to reverse this effect. Spruce was adversely affected when mixed with beech. At species level and under dry conditions, we found that night-time rehydration was reduced in all species, but beech had a greater capacity to rehydrate under high to moderate soil water availability than the conifers, even under high atmospheric water demand. Our study gives new insights into neighborhood effects on tree water status and highlights the importance of species-specific characteristics for tree-water relations in mixed-species forests. It shows that drought stress of European beech can be reduced by admixing Douglas fir, which may point towards a strategy to adapt beech stands to climate change.

Comparative transcriptomic insights into key genes for biomass production and lipid synthesis in Chlorella sorokiniana mutated by argon and air atmospheric and room temperature plasma at different culture stages: Common mechanisms and unique differences

Metabolic mechanisms driving rapid lipid production in atmospheric and room temperature plasma-mutagenized Chlorella sorokiniana remain unclear, hindering improvement in lipid productivity through genetic modification. This study investigated two dominant strains, ArX13 and AirX12, mutated by argon and air ARTP, for growth, lipid production, and transcriptomic changes across various culture stages. Results showed that biomass and lipid contents peaked in the late stage, with ArX13 and AirX12 achieving final biomass of 0.71 g/L and 0.70 g/L, and lipid content of 58.57 % glipid gbiomass−1 and 46.90 % glipid gbiomass−1, 2.20 and 1.77 times higher than the control, respectively. The maximum biomass and lipid productivity occurred at the mid-stage, with ArX13 and AirX12 showing biomass productivity of 0.025 gbiomass L−1 day−1 and 0.024 gbiomass L−1 day−1, and lipid productivity of 17.79 mglipid L−1 day−1 and 11.40 mglipid L−1 day−1, respectively. Transcriptomic analysis revealed minimal changes of gene expression during early and late stages, but significant biomass and lipid synthesis during the middle stage. Key genes like PDHB, ATP6A, LSC1 and OGDH were identified in the PPI network throughout the culture cycle, with PDHB remarkably promoting lipid precursor production, up-regulated 8.37 and 4.99-fold in M_ArX13-M_X0 and M_AirX12-M_X0, respectively. In addition, high expression of photosynthesis-related genes (psaL, psaO, psaD, psaK, psbP) contributed the superior lipid production for the argon-based ARTP case, highlighting common and intrinsic mechanisms regulating microalgal lipid accumulation under different ARTP mutations. This study shows that the selection of appropriate ARTP gases can maximize the lipid production of microalgal, and the discovery of some key genes can provide a theoretical basis for the selection of target genes for microalgal research, which is of great significance for promoting the research and development of microalgal lipid engineering.