Subject: Biology, Anatomy & Morphology Keywords: elevated CO2; nitrogen-fixing plants; herbivores; total phenolic compounds; C:N ratio
Online: 8 February 2021 (10:32:07 CET)
Many studies have found that future predicted CO2 levels (< 800 ppm) can increase plant mass but dilute N content in leaves, impacting antiherbivore compounds. Nitrogen-fixing plants may balance leaf C:N ratio under elevated CO2, counteracting this dilution effect. The aim of this study was to look at how nitrogen-fixing plants grow and respond to herbivore damage at different CO2 levels. Alnus incana ssp. rugosa was grown at 400, 800, or 1600 ppm CO2 in soil collected from the field, inoculated with Frankia and exposed to herbivores (Orgyia leucostigma). Elevated CO2 increased nodulated plant biomass and stimulated the nitrogen fixation rate in the early growth stage. However, nitrogen-fixing plants were not able to balance the C:N ratio under elevated CO2 after grown 19 weeks. When plant were grown at 400 and 1600 ppm CO2, herbivores preferred to feed on leaves of nodulated plants. At 800 ppm CO2, nodulated plants accumulated more total phenolic compounds in response to herbivore damage than plants in the non-Frankia and non-herbivore treatments. Our results suggest that plant leaf defence, not leaf nutritional content, is the dominant driver of herbivory and nitrogen fixing plants have limited ability to balance C:N ratios at elevated CO2 in natural soil.
ARTICLE | doi:10.20944/preprints201908.0314.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: brucellosis; elevated liver enzymes; hepatomegaly; children
Online: 29 August 2019 (17:22:42 CEST)
Background and Objective: In the present study, the purpose was to compare the demographic, clinical and laboratory results of pediatric brucella cases who had liver involvement and who had no specific organ involvement. Material and Methods: The data of 248 patients between 2 and 18 years of age diagnosed with Brucellosis between July 2017 and August 2018 were analyzed retrospectively. The patients who had liver involvement and who did not have other specific organ involvement were compared in terms of presentation, physical examination findings, age, gender, hemogram, AST, ALT, GGT, ALP, bilirubines, sedimentation, CRP, clinical and laboratory findings, and culture and relapse rates. Results: No significant differences were detected between the patients who had liver involvement (n=92) and who did not have specific organ involvement (n=156) in terms of diagnosis age and gender. Loss of appetite, nausea and sensitive stomach were higher in the patients who had hepatic involvement, and weariness was determined to be more in the control group patients. In the patients who had hepatic involvement, the hemoglobin and platelet values were lower, and the sedimentation, CRP and blood culture growth were higher. The relapse rates were lower in patients who had liver involvement. Conclusion: In patients who have liver involvement, in addition to elevated hepatomegaly and transaminase levels, the growth rate of the acute-phase reactants and brucella is higher in blood culture; and the relapse rate is lower after treatment. Brucellosis must be considered in the differential diagnosis of hepatomegaly and transaminase elevation where brucellosis is seen endemically. We believe that early diagnosis of brucellosis is important in treatment response.
REVIEW | doi:10.20944/preprints202008.0286.v2
Subject: Biology, Agricultural Sciences & Agronomy Keywords: elevated CO2; drought; photosynthesis; transpiration rate; stomatal conductance; C4 enzymes; malate; water deficit stress; abscisic acid
Online: 4 July 2022 (08:21:01 CEST)
The changing dynamics in climate is the primary and important determinant of agriculture productivity. The effects of this changing climate on overall productivity in agriculture can be understood when we study the effects of individual components contributing to the changing climate on plants and crops. Elevated CO2 (eCO2) and drought due to high variability in rainfall is one of the important manifestations of the changing climate. There is a considerable amount of literature that addresses climate effects on plant systems from molecules to ecosystems. Of particular interest is the effect of increased CO2 on plants in relation to drought and water stress. As it is known that one of the consistent effects of increased CO2 in the atmosphere is increased photosynthesis, especially in C3 plants, it will be interesting to know the effect of drought in relation to elevated CO2. The potential of elevated CO2 ameliorating the effects of water deficit stress is evident from literature suggesting that these two are agents are brothers in arms protecting the plant from stress rather than partnering in crime, specifically water deficit when in isolation. The possible mechanisms by which this occurs will be discussed in this minireview. Interpreting the effects of short-term and long-term exposure of plants to elevated CO2 in the context of ameliorating the negative impacts of drought will show us the possible ways by which there can be effective adaption to crops in the changing climate scenario.
ARTICLE | doi:10.20944/preprints201808.0070.v1
Online: 3 August 2018 (14:31:16 CEST)
Carbon fiber reinforced polymer (CFRP) has been used widely in strengthening of steel structures. Steel/CFRP systems subjected to elevated temperatures is realistic in a summer climate event in many countries where the temperature in steel may approach 50 °C or even higher, which will lead to the degradation of the bond performance between CFRP and steel. Therefore, predicting the bond behavior of the CFRP/steel system under elevated temperature is critical. This paper investigated the mechanical performance of CFRP/steel adhesively-bonded double strap joints at elevated temperatures. Thirty CFRP-steel double strap joints were tested to failure under temperatures between 10 °C and 90 °C. It was found that the joint failure mode changed from adherend failure to debonding failure as the temperature approached Tg. In addition, the ultimate load and joint stiffness decreased significantly at temperatures near to and greater than Tg. Based on the experimental results, a model is proposed to predict the bond stress of the CFRP/steel at different temperatures.
ARTICLE | doi:10.20944/preprints202110.0370.v1
Subject: Life Sciences, Other Keywords: photosynthesis; elevated CO2; Rubisco; electron transport; light; diurnal cycle
Online: 25 October 2021 (15:52:11 CEST)
The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 minutes using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 mol mol-1 and one at 600 mol mol-1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J, The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.
ARTICLE | doi:10.20944/preprints201912.0297.v1
Subject: Materials Science, General Materials Science Keywords: concrete-galvalume composite; elevated temperature; flexure behavior; numerical model; constitutive stress-strain
Online: 22 December 2019 (13:27:28 CET)
A galvalume corrugated sheet was utilized as formwork for a reinforced concrete beam in flexure. A numerical model was validated to the experimentally obtained data, and further adopted to simulate the behavior of this composite structure under elevated temperatures. The properties and constitutive stress-strain data of the basic materials were obtained from experiments, and superimposed into the finite element model. The study concluded that the load carrying capacity of the member decreased as a direct function on temperature increase, and the cracking moment was very sensitive to the temperature fluctuation. The elevated temperatures also altered the failure mode.
ARTICLE | doi:10.20944/preprints201806.0103.v1
Subject: Materials Science, General Materials Science Keywords: Al-Mn-Mg alloy; dispersoids; heat treatment; elevated temperature; strength; creep resistance
Online: 7 June 2018 (05:59:45 CEST)
Present work has systematically investigated the evolution of dispersoid and elevated-temperature properties including the strength and creep resistance during the various multi-step heat treatments in Al-Mn-Mg 3004 alloys. Results show that only α-Al(MnFe)Si dispersoid is observed in the studied temperature range (up to 625°C) and it coarsens with increasing temperature to 500°C but dissolves at 625°C. The evolution of elevated-temperature strength and creep resistance is greatly related to the temperature of each step during the multi-step heat treatments. Generally, lower temperature at the first-step heat treatment leads to higher properties while the properties decrease with increasing temperature of last-step heat treatment. Suitable models have been introduced to explain the evolution of strength and the creep threshold stress at elevated-temperature during the various heat treatments.
ARTICLE | doi:10.20944/preprints201807.0439.v1
Subject: Biology, Forestry Keywords: climate change; temperature stress; drought; elevated CO2; soil water; forest succession; mechanistic landscape model; LANDIS-II; PnET-Succession
Online: 24 July 2018 (05:34:08 CEST)
1) Background: Climate change may subject forests to climate conditions to which they are not adapted. Elevated temperatures reduce net photosynthesis by increasing respiration rates and increasingly long droughts dramatically increase morbidity. CO2 enrichment enhances productivity, but it is not clear to what extent CO2 enrichment can offset the negative effects of elevated temperatures and longer droughts. 2) Methods: We used a mechanistic landscape model to conduct controlled simulation experiments manipulating CO2 concentration, temperature, drought length and soil water capacity. 3) Results: We found that elevated CO2 stimulates productivity such that it dwarfs the negative effect caused by elevated temperature. Energy reserves were not as strongly mitigated by elevated CO2, and mortality of less competitive cohorts increased. Drought length had a surprisingly small effect on productivity measures, but had a marked negative effect on mortality risk. 4) Conclusions: Elevated CO2 compensated for the negative effect of longer droughts in terms of productivity measures, but not survival measures.
ARTICLE | doi:10.20944/preprints201809.0444.v1
Subject: Earth Sciences, Atmospheric Science Keywords: snow-darkening, light-absorbing aerosols, dust and black carbon, elevated-heat- pump effect, snow cover–monsoon relationship, Blanford hypothesis
Online: 22 September 2018 (23:18:38 CEST)
The impact of snow darkening by deposition of light absorbing aerosols (LAAs) on snow cover over the Himalaya-Tibetan-Plateau (HTP) and influence on the Asian monsoon are investigated using the NASA Goddard Earth Observing System Model Version 5 (GEOS-5). We find that during April-May-June, deposition of LAAs on snow leads to a reduction in surface albedo, initiating a sequence of feedback processes, starting with increased surface solar radiation, rapid snowmelt in HTP and warming of the surface and upper troposphere, followed by enhanced low-level southwesterlies and increased dust loading over the Himalayas-Indo-Gangetic Plain. The warming is amplified by increased dust aerosol heating, and subsequently amplified by latent heating from enhanced precipitation over the Himalaya foothills and northern India, via the Elevated Heat Pump (EHP) effect during June-July-August. The reduced snow cover in the HTP anchors the enhanced heating over the Tibetan Plateau and its southern slopes, in conjunction with an enhancement of the Tibetan Anticyclone, and the development of an anomalous Rossby wavetrain over East Asia, leading to weakening of the subtropical westerly jet, and northward displacement and intensification of the Mei-Yu rainbelt. Our results suggest that atmosphere-land heating by LAAs, particularly desert dust play a fundamental role in physical processes underpinning the snow-monsoon relationship proposed by Blandford more than a century ago.
ARTICLE | doi:10.20944/preprints202201.0194.v1
Subject: Life Sciences, Biochemistry Keywords: Helicobacter pylori; urease; neuroinflammation; tau hyperphosphorylation; pro-inflammatory cytokines; object recognition test; elevated plus maze; SH-SY5Y neuroblastoma cells; BV-2 microglia
Online: 13 January 2022 (15:37:01 CET)
Alzheimer’s disease (AD) causes dementia and memory loss in the elderly. Deposits of beta-amyloid peptide and hyperphosphorylated tau protein are present in AD’s brain. A filtrate of Helicobacter pylori’s culture was previously found to induce hyperphosphorylation of tau in vivo, suggesting that bacterial exotoxins could permeate the blood brain barrier and directly induce tau’s phosphorylation. H. pylori, which infects ~60% of the world population and causes gastritis and gastric cancer, produces a pro-inflammatory urease (HPU). Here the neurotoxic potential of HPU was investigated in cultured cells and in rats. SH-SY5Y neuroblastoma cells exposed HPU (50-300 nM) produced reactive oxygen species (ROS) and had an increased [Ca2+]i. HPU-treated BV-2 microglial cells produced ROS, cytokines IL-1β and TNF-α, expressed Iba1 and showed reduced viability, consistent with a neurotoxic effect of HPU. Rats received daily i.p. HPU (5 µg) for 7 days. Hyperphosphorylation of tau at Thr205, Ser199 and Ser396 sites was seen in hippocampal homogenates of treated rats, with no alterations in total tau or GSK-3b levels. HPU was not detected in the brain homogenates. Behavioral tests were performed to assess cognitive impairments. Our findings support previous data suggesting an association between infection by H. pylori and tauopathies such as AD, possibly mediated by its urease.