Removal Of Roots Research Articles

Differences in eco-physiological responses to the removal of adventitious roots between Syzygium nervosum A. Cunn. ex DC. and Syzygium cumini (L.) Skeels saplings under waterlogging

Differences in eco-physiological responses to the removal of adventitious roots between Syzygium nervosum A. Cunn. ex DC. and Syzygium cumini (L.) Skeels saplings under waterlogging

Long-Term Changes in Organic Matter Content and Soil Moisture Determine the Degree of Root and Soil Respiration.

Carbon in soil is one of the most important indicators of soil fertility. Part of the carbon stored in them is returned to the atmosphere during soil respiration. Climate change and inappropriate land use can accelerate these processes. Our work aimed to determine how soil CO2 emissions change over ten years as a result of litter manipulation treatments. Plots at the Síkfőkút DIRT (Detritus Input and Removal Treatments) experimental site include doubling either leaf litter or wood, and removing all aboveground litter, all root inputs, or removing all litter inputs. With the help of this, we were able to examine not only the effects of the different organic matter intake but also the effects of the different microclimates that occur as a result of the treatments. Total soil respiration (root and microbial respiration) is a result of a persistent lack or excess of soil organic matter relative to soil moisture. Based on our studies, the increase in the intensity of root respiration on wetter soils was only half of the increase in respiration associated with decomposition activity. The sustained growth of leaf litter significantly increases soil respiration, which can be partly explained by the more favorable supply of nutrients to the decomposing organisms, and partly by the more favorable microclimatic conditions, however, these effects were only valid in the case of wetter soils. In the dry summer environment, we experienced higher CO2 emissions during litter removal treatments. In the first period between 2002 and 2004, even wetter root removal treatments showed a significantly higher CO2 emission, while in the period 2010-2012, surface litter removal treatments. The permanent removal of surface litter in the drier summer period resulted in the formation of a dense crack network, which increased the CO2 emission of these soils, which increases the soil organic carbon loss of the soil. Our study proves the advantages of mulching in terms of a more favorable microclimate of the soil surface and a balanced carbon balance of the soil-plant system.

Hair root staining with Hematoxylin: Increasing the rate of obtaining DNA profiles in forensic casework

Hair evidence collected during a forensic investigation has the potential to provide valuable sourcing information through DNA analysis of its root. Over time, hair examiners at the North Carolina State Crime Laboratory observed hair roots being sent for DNA analysis were not yielding profiles as expected. Recent advancements in the Forensic Biology Section’s detection limits prompted research into whether changes to the current root removal protocol could increase the likelihood of developing a DNA profile from a hair root. An internal validation was completed for the method of Hematoxylin staining to screen telogen roots for DNA analysis. Over 900 head hairs from approximately 15 living donors were examined for telogen roots. Those roots were stained using Hematoxylin and examined for nuclei. The roots were separated into groups based on nuclei present: Group I (1–10 nuclei), Group II (11–20 nuclei), Group III (21–30 nuclei), Group IV (31–40 nuclei), and Group V (41 or greater nuclei). A set of 64 roots, including a Negative Control (0 nuclei) and a Positive Control (anagen or catagen roots), were sent for quantitative DNA analysis. The data showed a clear separation between Groups I and II, where 36% of Group I verses 80% of Group II passed the quantification cutoff. All samples in the Negative Control, Group I, and the Positive Control were then amplified along with a representative sample in Groups II through V. After amplification, the delineation between Groups I and II maintained with 27% of Group I verses 89% of Group II obtaining DNA profiles. As a result, the nuclei required to obtain a potential DNA profile at our laboratory is eleven or more. Prior to Hematoxylin, anagen, catagen, or telogen roots with follicular tissue were sent for DNA analysis, resulting in 32% of roots yielding DNA results. Following implementation of Hematoxylin into casework in March 2019, the success rate has more than doubled to 69%, illustrating the utility of Hematoxylin root staining in improving casework efficiency. Through this methodology, only roots with the best potential to develop a DNA profile are sent for testing, thereby decreasing DNA caseload, cost, and time of analysis. In fact, Hematoxylin staining has resulted in a 14% reduction in the number of hair roots forwarded for DNA analysis, meaning hairs not meeting nuclear threshold are preserved for future examinations.

Different eco-physiological responses to the removal of adventitious roots between Cleistocalyx operculatus and Syzygium cumini saplings under waterlogging condition

Different eco-physiological responses to the removal of adventitious roots between Cleistocalyx operculatus and Syzygium cumini saplings under waterlogging condition

Different effects of litter and root inputs on soil enzyme activities in terrestrial ecosystems

Soil extracellular enzymes are involved in the decomposition of plant litter and soil organic matter, and their activities are of critical significance to soil carbon and nutrient turnover in terrestrial ecosystems. However, the coupling of litter and root inputs and soil enzyme activities across terrestrial ecosystems still remains not fully understood. In this study, we compiled 788 paired observations to evaluate changes in soil β-1,4-glucosidase (BG), β-d-cellobiosidase (CBH), phenol oxidase (PHO), β-1,4-N-acetyl-glucosaminidase (NAG), and acidic phosphatase (AP) activities after the removal of litter, living roots, and both litter and living roots in different ecosystems (forests, grasslands, croplands and tundra). Soil BG, NAG, and AP activities were decreased by 22.5 %, 16.6 % and 28.7 %, respectively, after removing both litter and living roots, but these effects varied in different ecosystems. Removing both litter and living roots decreased soil BG and CBH activities in forests and BG activity in croplands but increased soil CBH activity in croplands. Soil NAG activity was decreased by 15.1 % in forests but increased by 6.1 % in croplands after both litter and living roots were removed, while soil AP activity was decreased significantly across all of the studied ecosystems after both litter and living root removal. However, litter addition greatly increased soil BG, CBH, NAG and AP activities, suggesting that soil enzyme activities involved in carbon, nitrogen and phosphorus cycling were strongly controlled by plant carbon input, with an additive effect of litter and root inputs observed for C-degrading enzymes. Our synthesis also found that these enzymatic responses to plant carbon input were strongly controlled by edaphic and not climatic factors across terrestrial ecosystems. These results suggested that soil enzyme activities increased after litter addition to accelerate the decomposition of litter input but decreased after litter removal. Removing both litter and root inputs had a similar but additive effect on soil enzyme activities across sites. Although these responses varied greatly among ecosystems and litter types, edaphic factors predominantly controlled enzymatic responses over terrestrial ecosystems. Our results highlighted the importance of plant inputs in enzymatically involved carbon and nutrient cycles in terrestrial ecosystems.

CURRENT TRENDS IN PERIODONTITIS TREATMENT AND PREVENTION: A LITERATURE OVERVIEW

The aim of this article is to review modern researches devoted to the study of methods of prevention and treatment of periodontitis. Results. It should be noted that the analysed scientific works only briefly touch on the issue of periodontitis prevention, noting that it depends on both oral hygiene and a person's lifestyle. To maintain healthy teeth and periodontal disease, dentists recommend: giving up smoking, eating a variety of foods, including vegetables and fruit in the diet, limiting the consumption of too cold and hot food, using dental floss and mouth rinses, choosing toothpaste and the hardness of the toothbrush taking into account the recommendations of the specialist Unfortunately, not all plaque can be removed at home. Hygiene becomes more difficult if the teeth are crowded, if there are prostheses or braces. Therefore, it is important to undergo preventive examinations every six months, not forgetting professional teeth cleaning at the dentist. Conservative treatment involves therapeutic (mechanical treatment of canals; medicinal (antiseptic) treatment of canals; if necessary, an incision to remove inflammatory products; sealing) and physiotherapeutic (UHF therapy; electrophoresis; laser therapy; therapeutic baths and pastes) procedures. Conservative treatment of periodontitis is accompanied by taking antibiotics. The surgical method of treatment involves resection of the tip of the tooth root with subsequent filling of the apical section of the canal; complete tooth root removal; tooth extraction. Due to the peculiarities of the anatomical structure of the root canals of the teeth, endodontic treatment becomes ineffective. Conclusion. At the current stage of development, the complex treatment of periodontitis has several treatment methods that combine the use of the most modern pharmaceuticals in combination with therapeutic and surgical methods, which in the future allows to obtain a fairly good and stable result.

Enzymatic activity of grains of different varieties of spring barley

The paper presents studies of the enzymatic activity of barley grains of different varieties. In experiments with different varieties of malting barley, the activity of isoforms of amylolytic enzymes was determined at pH = 5.5, 7.0, 8.0 using a phosphate buffer system (1/15 M phosphate buffer). The activity of enzymes in the germinated grain was determined after the removal of sprouts and roots. In experiments to determine the activity of amylases in the study of the action of enzymes in acidic (pH = 5.5), neutral (pH = 7) and alkaline (pH = 8) environments, it was found that in germinated barley grain, acid isoenzymes α- and β-amylases, as well as neutral and alkaline isoenzymes. It is shown that in the process of malting on the 7th day, the activity of amylotic enzymes increases significantly, which is of great importance in the brewing industry. During the germination of barley seeds under standard conditions, an active complex of enzymes amylases, proteases, cytases, oxidoreductases is formed, which dissolve endosperm cells and convert reserve substances into soluble compounds.

Cervical Abrasion and Gingival Recession in Dental Polyclinic Patients

Background: The most common dental health problem in Indonesia is dental caries. The prevalence of caries by 92.2% and ages 35-44 years experienced dental health problems, with the DMF-T index of 6.9 meaning the average number of tooth decay was 6 to 7 teeth per person. One effort that can be carried out to prevent caries is to pay attention to the cleanliness of the oral cavity area especially teeth, plaque cleaning every day is by brushing teeth. Inappropriate brushing techniques can lead to the removal of tooth roots by transferring gingival margin bonds to the apical position of the cementoenamel junction which can result in tooth abrasion and gingival recession. The purpose of this study was to determine the cervical abrasion and gingival recession in dental polyclinic patients at the Pertamedika Clinic Office Center. Method: This study used a descriptive method. The sample of this study was using purposive sampling as many as 54 respondents. The data used are secondary data taken from the patient’s medical record. Results: The results of cervical abrasion studies showed that 25 people (46.3%) did not have cervical abrasion and 29 people (53.7%) had cervical abrasion. Respondents did not have gingival recession of 26 people (48.1%) and those who had gingival recession were 28 people (51.9%). Conclusions: Most of the Pertamedika Center Office clinic patients have cases of cervical abrasion and gingival recession.

Primary dental care treatment in primary Sjögren's syndrome: a possible role in improving salivary flow rate.

Primary Sjögren's syndrome (pSS) is an inflammatory chronic disorder that mainly affects exocrine glands. Additionally, oral infections can aggravate the glandular dysfunction. However, data on primary dental care (PDC) treatment in pSS are scarce. This study aimed to appraise the impact of PDC on the Xerostomia Inventory (XI), unstimulated/stimulated salivary flow rates and salivary cytokine profile in pSS. Fifty-two pSS patients and 52 sex- and age-matched control participants without systemic autoimmune diseases were included in a prospective study. At inclusion, all participants were assessed through a standardised protocol, measurement of salivary pro-inflammatory cytokines, and underwent PDC. Dental procedures included: oral hygiene guidance, restorative treatment of caries, surgical removal of residual roots and impacted or partially erupted teeth, cysts, supra and subgingival periodontal scaling and treatment of soft tissue disorders (removal of lesions and treatment of opportunistic infections). After 3 months, the clinical/laboratorial assessments were repeated. At inclusion, the Decayed, Missing and Filled Teeth (DMFT) index was higher in the pSS patients than in the control group (13.3±8.2 vs. 8.6±6.2, p=0.002), whereas periodontal parameters were comparable in both groups (p>0.05). After PDC, 26.9% of pSS patients showed a reduction of at least 6 points (clinical improvement) in XI, but mean XI remained unchanged (p=0.285). PDC resulted in an increase in mean unstimulated (p<0.001) and stimulated (p=0.001) salivary flow rates in pSS, with no change in salivary cytokine profile (p≥0.05). PDC promoted improvement in unstimulated and stimulated salivary flow rates in pSS. This novel finding reinforces the recommendation of this strategy for pSS patients. gov (Identifier: NCT03711214).

‘TifEagle’ Bermudagrass’ Response to Commercial Biostimulants

Biostimulant use in the US is currently not regulated; therefore, much speculation exists as to product benefit claims. Three greenhouse trials were conducted with greens grade ‘TifEagle’ bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) Clemson, SC during 2019 and 2020. Trial one simulated recovery from “divot” injury while trial two simulated recovery following sod harvest and measured growin rate using either pure sand or a native soil. Trial three was a rooting experiment performed in lysimeters to ascertain root growth following biostimulant use. Three commercial biostimulants (EarthMAX, Worm Power, and Hydra-Enrich 20) were used for all three studies, each applied individually or, applied with an 18-3-4 fertilizer (named: “Fert”) at 0.2 lb N/1,000 ft2 (9.76 kg N/ha). Trial one measured normalized difference vegetation index (NDVI) ratings where EarthMAX (EM) (mean=0.576) had ~6.4%, ~3.3%, and 5.4% less recovery compared to untreated control, Hydra-Enrich 20 (HH) and Worm Power (WP), respectively. Similar results were provided from digitized photographs where EM+F (mean=0.586) treated turf recovery was ~7% less than fertilizer, and ~11% less than HH+F. Without additional fertilizer, EM (Mean=0.415) was significantly lower in coverage versus all other treatments, including untreated (~21%). From image analysis for trial two, the native soil plus fertilizer resulted in HH+F (Mean=0.375) being significantly less than EM+F (~17%), WP (~12%) and fertilizer (~13%). From NDVI ratings in trial three, EM (mean = 0.542) had significantly greater vegetative index than HH (~16%) and WP (~13%). Although, significant differences were technically recorded for the digital measurements, treatment differences were difficult to detect with the naked eye. Overall, positive results from ratings were only seen in turf subjected to extreme stress from the continual removal of roots every four weeks.

Effects of Litter and Root Manipulations on Soil Bacterial and Fungal Community Structure and Function in a Schrenk's Spruce (Picea schrenkiana) Forest.

Soil microorganisms are the key driver of the geochemical cycle in forest ecosystem. Changes in litter and roots can affect soil microbial activities and nutrient cycling; however, the impact of this change on soil microbial community composition and function remain unclear. Here, we explored the effects of litter and root manipulations [control (CK), doubled litter input (DL), litter removal (NL), root exclusion (NR), and a combination of litter removal and root exclusion (NI)] on soil bacterial and fungal communities and functional groups during a 2-year field experiment, using illumina HiSeq sequencing coupled with the function prediction platform of PICRUSt and FUNGuild. Our results showed that litter and root removal decreased the diversity of soil bacteria and fungi (AEC, Shannon, and Chao1). The bacterial communities under different treatments were dominated by the phyla Proteobacteria, Acidobacteria, and Actinomycetes, and NL and NR reduced the relative abundance of the first two phyla. For the fungal communities, Basidiomycetes, Ascomycota, and Mortierellomycota were the dominant phyla. DL increased the relative abundance of Basidiomycetes, while NL and NR decreased the relative abundance of Ascomycota. We also found that litter and root manipulations altered the functional groups related to the metabolism of cofactors and vitamins, lipid metabolism, biosynthesis of other secondary metabolites, environmental adaptation, cell growth, and death. The functional groups including ectomycorrhizal, ectomycorrhizal-orchid mycorrhizal root-associated biotrophs and soil saprotrophs in the fungal community were also different among the different treatments. Soil organic carbon (SOC), pH, and soil water content are important factors driving changes in bacterial and fungal communities, respectively. Our results demonstrate that the changes in plant detritus altered the soil microbial community structure and function by affecting soil physicochemical factors, which provides important data for understanding the material cycle of forest ecosystems under global change.

Changes in plant inputs alter soil carbon and microbial communities in forest ecosystems.

Global changes can alter plant inputs from both above- and belowground, which, thus, may differently affect soil carbon and microbial communities. However, the general patterns of how plant input changes affect them in forests remain unclear. By conducting a meta-analysis of 3193 observations from 166 experiments worldwide, we found that alterations in aboveground litter and/or root inputs had profound effects on soil carbon and microbial communities in forest ecosystems. Litter addition stimulated soil organic carbon (SOC) pools and microbial biomass, whereas removal of litter, roots or both (no inputs) decreased them. The increased SOC under litter addition suggested that aboveground litter inputs benefit SOC sequestration despite accelerated decomposition. Unlike root removal, litter alterations and no inputs altered particulate organic carbon, whereas all detrital treatments did not significantly change mineral-associated organic carbon. In addition, detrital treatments contrastingly altered soil microbial community, with litter addition or removal shifting it toward fungi, whereas root removal shifting it toward bacteria. Furthermore, the responses of soil carbon and microbial biomass to litter alterations positively correlated with litter input rate and total litter input, suggesting that litter input quantity is a critical controller of belowground processes. Taken together, these findings provide critical insights into understanding how altered plant productivity and allocation affects soil carbon cycling, microbial communities and functioning of forest ecosystems under global changes. Future studies can take full advantage of the existing plant detritus experiments and should focus on the relative roles of litter and roots in forming SOC and its fractions.

川中丘陵区冬水田种植模式转旱作土壤呼吸组分特征及碳平衡

PDF HTML阅读 XML下载 导出引用 引用提醒 川中丘陵区冬水田种植模式转旱作土壤呼吸组分特征及碳平衡 DOI: 10.5846/stxb202105281410 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: “十三五”国家重点研发计划"粮食丰产科技创新"专项项目(2017YFD0301702) Carbon balance and characteristics of soil respiration components during the transition from paddy field to upland in the hilly region of central Sichuan Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:冬水田-水稻是川中丘陵区传统的稻田种植模式,冬水田种植模式转变是实现多熟种植及机械化的重要途径。为探究冬水田-水稻种植模式转旱作过程中作物季及休闲期土壤呼吸速率及其组分构成,试验设置冬水田-水稻转旱作(FTD)、冬水田-水稻(FR)和冬闲田-玉米(FM)3种不同种植模式,采用根排除法和静态明箱-气相色谱法原位取样测定作物季及季后休闲期土壤呼吸及其组分,并通过测算净生态系统生产力(NEP)进而判断冬水田-水稻转旱作过程的农田系统碳汇强度。结果表明:(1)FTD显著提高了土壤总呼吸速率及其自养和异养呼吸速率,从而提高了其累积排放量(P<0.05)。与FR相比,FTD的土壤总呼吸及其自养和异养呼吸的累积排放量分别提高了13.14倍、11.32倍和15.56倍(P<0.05);与FM相比,FTD的土壤总呼吸及其自养和异养呼吸的累积排放量分别提高了70.56%、40.83%和115.47%(P<0.05)。(2)与FR和FM相比,FTD均降低了土壤呼吸及其组分的温度敏感性(Q10),且土壤总呼吸的温度敏感性介于异养呼吸和自养呼吸之间。(3)FR,FM和FTD的净生态系统生产力(NEP)均为正值,其数值分别为7911.66 kg/hm2,5667.89 kg/hm2和1583.46 kg/hm2,均表现为大气CO2的碳汇,但与FR与FM相比,FTD显著降低了其净生态系统生产力,呈现出较弱的碳汇。 Abstract:Winter paddy field-rice is a traditional rice planting pattern in the hilly areas of central Sichuan Province. The transformation of winter paddy field-rice planting pattern is an important measure to promote multi-cropping and mechanized cropping production. To investigate the soil respiration rate and its composition during crop season and fallow period during the transition from winter paddy field-rice to upland cropping (FTD), three different cropping patterns were set up in this experiment, including paddy field-rice to upland cropping (FTD), paddy field-rice (FR), and fallow field-corn (FM). Root removal method and static chamber gas chromatography were used to determine soil respiration and its components in crop season and fallow period after crop was harvested. The intensity of farmland carbon sink of FTD was evaluated by calculating net ecosystem productivity (NEP). The results showed that: (1) the total soil respiration rate, autotrophic respiration rate and heterotrophic respiration rate significantly increased in FTD than FR and FM (P<0.05). Compared with FR, the cumulative emissions amount of total soil respiration, autotrophic and heterotrophic respiration increased by 13.14 times, 11.32 times, and 15.56 times, respectively (P<0.05); Compared with FM, the cumulative emissions amount of the total soil respiration, autotrophic and heterotrophic respiration increased by 70.56%, 40.83% and 115.47%, respectively (P<0.05). (2) The respiration temperature sensitivity (Q10) value of total soil respiration, autotrophic respiration and heterotrophic respiration decreased in FTD than FR and FM. Meanwhile Q10 value of total soil respiration was between heterotrophic respiration Q10 value and autotrophic respiration Q10 value. (3) The NEP of FR, FM and FTD were positive, and their values were 7911.66 kg/hm2, 5667.89 kg/hm2 and 1583.46 kg/hm2, respectively. The three plant patterns were all the carbon sink of atmospheric CO2. Whereas, because the NEP in FTD was significantly lower than FR and FM, it only showed a weak carbon sink in FTD than that in FR and FM. 参考文献 相似文献 引证文献

Digital guides to facilitate retained root removal and simultaneous implant placement

The aim of this study was to report the use of digital guides to locate impacted residual roots (IRR) (location guide) and to simultaneously insert dental implants (surgical guide). This case series included five patients. The IRR was first removed through a lateral window approach using the digital location guide, then the implant was placed simultaneously with the implant surgical guide. Definitive restorations were completed after a 6-month healing period. An average of 13.0 ± 3.1 minutes was required to locate the IRR. The implant stability quotient (ISQ) was obtained during surgery and before digital coping using a non-invasive resonance frequency measurement. The average ISQ during surgery for the five dental implants was 60.2 ± 6.3, and the value increased to 66.6 ± 4.8 before final restoration. The average deviations at the implant neck and root apex were 0.48 ± 0.25 mm and 0.74 ± 0.46 mm, respectively. The average angular deviation was 3.5 ± 1.4°. Bone resorption at the implant neck was a mean 0.072 ± 0.041 mm before final restoration. All implants functioned well at 1 year after final restoration. The application of surgical guides in the extraction of IRR enabled crestal bone preservation and simultaneous implant placement.

Characteristics and Management Plan for the Distribution of Nelumbo nucifera community in Junam Wetland

Background and objective If the &lt;italic&gt;Nelumbo nucifera&lt;/italic&gt; spreads in a wetland at a high density, it can have considerable positive and negative ecological effects on habitats. For this reason, it is necessary to precisely investigate the impacts of its rapid proliferation. This study was conducted to propose the distribution and management of &lt;italic&gt;N. nucifera&lt;/italic&gt;, which can cause the degradation of wildlife habitats due to the rapid spread of internal and external environmental factors that may affect the Junam wetland ecosystem. Methods For the investigation and analysis of physical and ecological characteristics, factors of the abiotic environment such as general weather conditions, topography and water depth structure, and soil and water quality analysis, and bioenvironment characteristics such as changes in the &lt;italic&gt;N. nucifera&lt;/italic&gt; community distribution were evaluated. To assess whether the differences in the soil depth and physicochemical characteristics between the &lt;italic&gt;N. nucifera&lt;/italic&gt; community and the aquatic plant community are statistically significant, a One-way ANOVA was executed. Results &lt;italic&gt;N. nucifera&lt;/italic&gt; was presumably introduced in approximately 2007 and observed at a prevalence of only 0.8% in 2009, but had expanded to 11.1% in 2014. After that, the area was increased to 19.3% in 2015 and 40.0% in 2017, about twice that of the previous survey year. The rapid diffusion of an &lt;italic&gt;N. nucifera&lt;/italic&gt; colony can have adverse effects on wildlife habitats and biodiversity at Junam Wetland. To solve these problems, four management methods can be proposed; water level management, mowing management, installation of posts and removal of lotus roots. Control of the &lt;italic&gt;N. nucifera&lt;/italic&gt; community using these methods was judged to be suitable for cutting and water level management when considering expansion rate, water level variation, and wildlife habitat impacts. Conclusion As the biotic and abiotic environmental factors are different for each wetland, it is necessary to determine the timing and method of management through a detailed investigation.

The ‘pargasosphere’ hypothesis: Looking at global plate tectonics from a new perspective

Apart from the lithosphere-asthenosphere boundary (LAB), mid-lithospheric discontinuities (MLDs) in thick and old continental lithospheres appear to play an important role in global plate tectonics. Initiation of intra-continental subduction, delamination of the lower continental lithospheric mantle and removal of cratonic roots are likely to occur along MLDs. Here we introduce the ‘pargasosphere’ hypothesis which could account for the origin of both boundaries. The observation that pargasitic amphibole is stable even at very low bulk ‘water’ concentration (~a few hundreds ppm wt.) implies that the solidus of the shallow upper mantle (<3 GPa) is usually the pargasite dehydration solidus at ~1100 °C. In young continental and oceanic lithosphere (<70 Ma) this solidus defines the LAB. The LAB separates the deeper, partial melt bearing asthenosphere from the shallower melt barren lithosphere, explaining their contrasting rheology. In old continents pargasite breaks down at the sub-solidus pargasite dehydration boundary at ~3 GPa and liberates ‘water’-rich fluids. This latter process may be responsible for the formation of MLDs. The occurrence of partial melts or fluids beyond the pargasite stability field can explain commonly observed geophysical anomalies associated with the LAB and MLDs. We present forward modelled variations of shear wave velocity and resistivity at the LAB and MLDs for idealised lithospheric columns. These columns are constructed based on the ‘pargasosphere’ hypothesis and geotherms corresponding to continental lithospheres with various tectono-thermal ages. The ‘pargasosphere’ hypothesis offers a number of other empirically testable implications. For instance, cooling asthenosphere beneath young extensional continental and oceanic lithosphere settings can be the source of surface CO 2 emanations even at locations distant from areas with active volcanoes. The Vrancea zone (Eastern Europe) appears to be a suitable site for testing the ‘pargasosphere’ hypothesis for elucidating the origin of intermediate-depth earthquakes (70–300 km) and to explain the delamination of the lower continental lithospheric mantle. • ‘Pargasosphere’ refers to part of the upper mantle where pargasite is stable. • The rheology of the shallow upper mantle (<100 km) is controlled by pargasite. • The upper limit of pargasite stability defines mid-lithosphere discontinuities. • Along this horizon, the lower part of the continental lithosphere can delaminate. • In the cooling asthenosphere, formation of pargasite can lead to CO 2 emission.

Depletion of bioavailable As/Cd with rice plant from paddy soils of high contamination risk

Co-uptake and high accumulation of As and Cd by rice is an outstanding issue threatening public health. From the viewpoint of soil cleanup, however, efficient As/Cd extraction by this paddy-adapted plant, followed by biomass removal, could provide a major pathway depleting As/Cd accumulation in paddy soils and thus inhibiting their transfer in food chain. Here a field trial was performed to identify the significance of As/Cd cleanup from paddy soil by rice. 88 % and 51 % of total extracted As and Cd were retained in root. To eliminate specifically rice-available As/Cd pool and obstruct their cycling back to soil, one crop of rice root was removed, leading to the depletion of 46 % and 69 % of plant available As (soluble & exchangeable) and Cd (exchangeable & carbonate-bound), respectively. In the following cultivation on the post-cleanup field, polished rice As fell from 0.23 mg kg−1 to 0.12 mg kg−1, markedly lower than the Chinese (WHO) limit (0.2 mg kg−1). Meanwhile, white rice Cd decreased by 24 %. This field work identified that As/Cd co-extraction by paddy-adapted rice plant, followed by root removal, as a primary step toward rice safety in areas with high contamination risk but little reserved paddy resources.

Shoot-Root Interplay Mediates Defoliation-Induced Plant Legacy Effect.

Shoot defoliation by grazers or mowing can affect root traits of grassland species, which may subsequently affect its aboveground traits and ecosystem functioning (e.g., aboveground primary production). However, experimental evidence for such reciprocal feedback between shoots and roots is limited. We grew the perennial grass Leymus chinensis–common across the eastern Eurasian steppe–as model species in a controlled-hydroponics experiment, and then removed half of its shoots, half of its roots, or a combination of both. We measured a range of plant aboveground and belowground traits (e.g., phenotypic characteristics, photosynthetic traits, root architecture) in response to the shoot and/or root removal treatments. We found the regenerated biomass was less than the lost biomass under both shoot defoliation and root severance, generating a under-compensatory growth. Root biomass was reduced by 60.11% in the defoliation treatment, while root severance indirectly reduced shoot biomass by 40.49%, indicating a feedback loop between shoot and root growth. This defoliation-induced shoot–root feedback was mediated by the disproportionate response and allometry of plant traits. Further, the effect of shoot defoliation and root severance on trait plasticity of L. chinensis was sub-additive. That is, the combined effects of the two treatments were less than the sum of their independent effects, resulting in a buffering effect on the existing negative influences on plant persistence by increased photosynthesis. Our results highlight the key role of trait plasticity in driving shoot–root reciprocal feedbacks and growth persistence in grassland plants, especially perennial species. This knowledge adds to earlier findings of legacy effects and can be used to determine the resilience of grasslands.

Response of soil bacterial communities to organic carbon input under soil freeze-thaw in forest ecosystems

The soil microbial community controls the biogeochemical cycle of elements critical to plant growth. Different carbon input modes have different effects on soil carbon storage and the microbial community, but the effects of carbon input control on soil microbial diversity and community structure in temperate forests remain unclear. We used high-throughput 16SrRNA gene sequencing and ecological network analysis methods to analyze the soil bacterial community, symbiotic network, and key species of three different carbon input treatments (litter removal, root removal, litter and root removal) in temperate natural secondary forests during the freeze-thaw season and growing season. The results showed that the change in the carbon source input led to a change in the way in which soil bacteria used carbon, which was mainly manifested as follows: (1) The relative abundance of Acidobacteria, which was oligotrophic bacteria, significantly decreased in the sample plots where the root system was removed. (2) In the litter removal treatment, the abundance of bacteria with functions related to the absorption of CH4 decreased. (3) The correlation between the module characteristic genes in the bacterial network analysis and the physical and chemical properties of soil, CK modules were grouped separately, and the change in the correlation may also indicate the change in the way soil bacteria use carbon. Second, the influence of belowground roots on the soil bacterial community structure was more significant than that of aboveground litter. The root system had a greater influence on the soil bacterial community. Third, the decrease of organic carbon input reduced the stability of the soil bacterial network, and the proportion of positive connections in the bacterial network for litter removal and root treatment increased significantly, indicating that these bacterial communities had the same change trend as the fluctuation of the environment. Finally, the freeze-thaw season had a greater impact than the growing season on bacterial diversity, community structure, and function. The freeze-thaw process allowed the bacterial community to respond to root removal more significantly, and the structural changes were mainly due to changes in temperature, water content, dissolved organic carbon, and nitrate nitrogen.

Self-confidence in oral and maxillofacial surgery: a cross-sectional study of undergraduate dental students at Kuwait University

BackgroundTo evaluate the self-confidence of undergraduate dental students in relation to oral and maxillofacial surgery (OMFS) to assess the teaching curriculum at Kuwait University using a validated questionnaire originally developed by the Association of British Academic Oral Maxillofacial Surgeons (ABAOMS).MethodsA cross-sectional survey of sixth year (n = 20) and seventh year (n = 19) dentistry students was conducted by Kuwait University Faculty of Dentistry between the 1st and 15th of May 2020. The ABAOMS questionnaire is composed of 17 questions assessing various areas of the undergraduate OMFS curriculum. The response options to the questionnaire utilised a Likert scale. Independent sample t-tests were performed to assess the difference in responses between the 2 year groups. Spearman’s rho correlations were calculated to measure the strength of association between confidence in all aspects of surgical and forceps exodontia.ResultsA total of 39 questionnaires were completed by the students. The majority of students expressed feelings of confidence that they have enough knowledge to undertake independent practice (61%). General aspects of the questionnaire were answered favourably except for surgical extraction of teeth, in which both classes reported a lower level of self-confidence.ConclusionsThe ABAOMS survey revealed the students’ self-confidence in undertaking independent practice and preforming basic oral surgery procedures. Students felt comfortable with exodontia using forceps and elevators, root removal, managing acute pericoronitis, managing haemorrhage from a socket, assessing impacted teeth, and recognising the clinical features of potentially malignant and malignant lesions of the oral cavity. They reported a lower level of confidence in performing surgical procedures.