In the present work, computational fluid dynamics study of stirred tanks of three sizes (20L, 400L and 5000L) provided with helical coils has been carried out. Various design parameters (impeller diameter, type and clearance) and operational parameters (Reynolds Number and Power per unit volume) have been varied and their effect on process side heat transfer coefficient has been studied. CFD model is validated with experimental work of Cummings and West and in house experimentation. Design settings of D/T=0.5, C/T=0.33 for PBTD450 resulted in maximum heat transfer (5440 W/m2K for P/V=1000 W/m3). For constant RPM and constant D/T (Constant Reynolds Number), Increasing the power number of impeller increased process side HTC at the cost of increased power requirement (decreasing efficiency). In such cases, proper selection of impeller system needs to be made based on the requirements of heat removal and optimizing parameters such as product yield, product quality etc.
The strategy of constructing catalytic membrane has a significant influence on its structure and performance. In this work, Co3O4-Cx@SiO2 nanofiber membranes (NFMs) were fabricated by an in-situ growth–pyrolysis–oxidation strategy. The Co3O4-Cx catalyst derived from ZIF-67 was wrapped around nanofibers, which helps to maintain a stable membrane structure, then suppressing the reduction of gas permeability. Among the Co3O4-Cx catalyst, the carbon skeleton can prevent the agglomeration of Co3O4 nanoparticles, obtaining an ultra-fine Co3O4 nanoparticles with high dispersibility, redox property and surface area. The obtained Co3O4-C300@SiO2 NFM exhibits excellent filtration efficiency and low pressure drop for PM2.5 (99.99% and 55 Pa) and outstanding catalytic performance with T90 of 245 °C for NH3-SCR, which is 40.3% higher than that of Co3O4@SiO2 NFM. This work might provide a universal strategy for the preparation of catalytic membrane with high-performance.
A thermodynamically consistent model for the carbon dioxide (CO2) absorption in aqueous alkanolamine system is of great importance in the research and development of a CO2 capture process. To facilitate the development of thermodynamic models, linear Gibbs free energy, enthalpy, and heat capacity relationships using well-known amines as reference are used to correlate the standard reference state properties of ionic species with those of molecular species in the electrolyte system, which has been approved to provide a reliable and consistent way to estimate required parameters when there is minimal or no appropriate experimental data available. The proposed relationships have been applied to the development of an electrolyte Non-Random Two Liquid (NRTL) activity coefficient model for CO2 absorption in aqueous 1-amino-2-propanol (A2P) solution, as an example to demonstration the methodology. With limited vapor-liquid equilibrium data and other thermodynamic properties, the parameters in the electrolyte NRTL model are identified with good accuracy.
This work aims to study the gas phase hydrodynamics in a stirred tank with a surface-aerated long-short blades agitator by the Eulerian‒Eulerian approach coupled with population balance model. Predicted local gas holdup and bubble size distribution agree well with those measured by a conductivity probe technique. The predictions demonstrate that the pressure depression in the center is the main driving force for gas suction and the downward flow carries the bubbles down to redistribute in the whole tank. The gas phase has higher gas holdup with large bubble size in the upper part and lower gas holdup but with small bubble size in the lower part of the tank. The predicted gas-liquid mass transfer coefficients agree well with our previous experimental results and just depends on the power consumption per unit volume when the aspect ratio of the liquid height to the tank diameter varies from 1.1 to 2.0.
Plants use seasonal cues to initiate flowering at an appropriate time of year to ensure optimal reproductive success. The circadian clock integrates these daily and seasonal cues with internal cues to initiate flowering. The molecular pathways that control the sensitivity of flowering to photoperiod (daylength) are well described in the model plant Arabidopsis. However, much less is known in crop species, such as the legume family species. Here we performed a flowering time screen of a TILLING population of Medicago truncatula and found a line with late-flowering and altered light-sensing phenotypes. Using RNA-sequencing, we identified a nonsense mutation in the Phytochromobilin Synthase (MtPΦBS) gene, which encodes an enzyme that carries out the final step in the biosynthesis of the chromophore required for phytochrome (PHY) activity. The analysis of the circadian clock in the MtpΦbs mutant revealed a shorter circadian period, which was shared with the phyA mutant. The MtpΦbs and MtphyA mutants showed downregulation of FT floral regulators MtFTa1, MtFTb1/b2 and a shift in phase for morning and night core clock genes. Our findings show that PHYA is necessary to synchronize the circadian clock and integration of light signaling to promote expression of the MtFT genes to precisely time flowering.
Elucidating mechanisms underlying community assembly and biodiversity patterns is central to ecology and evolution. Genome size (GS, i.e. nuclear DNA content) determines species’ capacity to tolerate environmental stress and therefore potentially drives community assembly. However, its role in driving β-diversity (i.e., spatial variability in species composition) remains unclear. We measured GS for 161 plant species and investigated their occurrences within plant communities across 52 sites spanning a 3200-km transect in the temperate grasslands of China. Using species distribution modelling, we found that environmental factors showed larger effects on β-diversity of large-GS than that of small-GS species and that communities with abundant resources had a greater representation of large-GS species. The latter finding was confirmed following analysis of data from a 10-yr resource (water, nitrogen, and phosphorus) manipulation experiment in which resource addition resulted in increased community weighted GS based on plant biomass estimates, suggesting that large-GS species are more sensitive to environmental resource limitation and explaining the greater environmental selection on β-diversity of large-GS species. These findings highlight the roles of GS in driving community assembly and predicting species responses to global change.
With open-access publishing authors pay an article processing charge and subsequently their article is freely available online. These charges are beyond the reach of most African academics. Thus, the trend towards open access publishing will shift the business model from a pay-wall model, where access to literature is limited, to a pay-to-publish one, where African scholars cannot afford to publish. We explore the costs of publishing and the ability of African scholars to afford to publish as open access. Three-quarters of the 40 top ecology journals required payment for open-access publishing (average cost $3,150). Paying such fees is a hardship for African scholars as grant funding is not available and it is not feasible to pay the fees themselves as salaries are low. We encourage funders and publishers to facilitate an equitable publishing model that allows African scholars to make their research available through open-access publishing.
While environmental science, and ecology in particular, is working to provide better understanding to base sustainable decisions on, the way scientific understanding is developed can at times be detrimental to this cause. Locked-in debates are often unnecessarily polarized and can compromise any common goals of the opposing camps. The present paper is inspired by a resolved debate from an unrelated field of psychology where Nobel laureate David Kahneman and Garry Klein turned what seemed to be a locked-in debate into a constructive process for their fields. The present paper is also motivated by previous discourses regarding the role of thresholds in natural systems for management and governance, but its scope of analysis targets the scientific process within complex social-ecological systems in general. We identified five features of environmental science that appear to predispose for locked-in debates: 1) The strongly context dependent behaviour of ecological systems. 2) The dominant role of single hypothesis testing. 3) The high prominence given to theory demonstration compared investigation. 4) The effect of urgent demands to inform and steer policy. This fertile ground is further cultivated by human psychological aspects as well as the structure of funding and publication systems.
Aim. Cancer patients with reduced dihydropyrimidine dehydrogenase (DPD) activity are at increased risk of severe fluoropyrimidine (FP)-related adverse events (AE). Guidelines recommend FP dosing adjusted to genotype-predicted DPD activity based on four DPYD variants (rs3918290, rs55886062, rs67376798, rs56038477). We evaluated relationship between three further DPYD polymorphisms [c.496A>G (rs2297595), *6 c.2194G>A (rs1801160) and *9A c.85T>C (rs1801265)] and the risk of severe AEs. Methods. Consecutive FP-treated adult patients were genotyped for “standard” and tested DPYD variants, and for UGT1A1*28 if irinotecan was included, and were monitored for the occurrence of grade ≥3 (National Cancer Institute Common Terminology Criteria) vs. grade 0-2 AEs. For each of the tested polymorphisms, variant allele carriers were matched to respective wild type controls (optimal full matching combined with exact matching, in respect to: age, sex, type of cancer, type of FP, DPYD activity score, use of irinotecan/UGT1A1, adjuvant therapy, radiotherapy, biological therapy and genotype on the remaining three tested polymorphisms). Results. Of the 503 included patients (82.3% colorectal cancer), 283 (56.3%) developed grade ≥3 AEs, mostly diarrhea and neutropenia. Odds of grade ≥3 AEs were higher in c.496A>G variant carriers (n=127) than in controls (n=376) [OR=5.20 (95%CI 1.88-14.3), Bayesian OR=5.24 (95% CrI 3.06-9.12)]. Odds tended to be higher in *6 c.2194G>A variant carries (n=58) than in controls (n=432) [OR=1.88 (0.95-3.73), Bayesian OR=1.90 (1.03-3.56)]. *9A c.85T>G did not appear associated with grade ≥3 AEs (206 variant carriers vs. 284 controls). Conclusion. DPYD c.496A>G variant might need to be considered for inclusion in the DPYD genotyping panel.
Background and Purpose: Changes to spinal glycinergic signalling are a feature of pain chronification. Normalising those changes by inhibiting glycine transporter-2 (GlyT2) is a promising treatment strategy. However, existing GlyT2 inhibitors e.g. ORG25543 are limited by narrow therapeutic windows and severe dose-limiting side effects such as convulsions, and are therefore poor candidates for clinical development. Experimental Approach: Analgesic and side-effect properties of intraperitoneally administered oleoyl-D-lysine, a lipid-based GlyT2 inhibitor, were characterised in mice. Analgesia was assessed in models of chronic neuropathic and inflammatory pain via the von Frey test, and acute nociception via hotplate. Side effects were scored via numerical rating scale, convulsions score, the Rotarod test and whole-body plethysmography for respiratory depression. Key Results: Oleoyl-D-lysine produced significant analgesia/anti-allodynia in the model for chronic neuropathic pain but not for chronic inflammatory or acute pain. No side effects were seen at the peak analgesic dose, 30 mg kg-1. Mild side effects were observed at the highest dose, 100 mg kg-1, in the numerical rating score, but no convulsions. These results contrasted markedly with ORG25543, which produced significant analgesia only at the lethal or near-lethal dose of 50 mg kg-1. At this dose, ORG25543 caused severe side effects on the numerical rating score, severe convulsions, and Rotarod impairment. Oleoyl-D-lysine (30 mg kg-1) did not cause any respiratory depression, a problematic side effect of opiates. Conclusions and Implications: Oleoyl-D-lysine safely and effectively reverses neuropathic pain in mice. GlyT2 inhibitors may be better suited to treating pain of neuropathic origin over other pain aetiologies.
Associations between host genotype and the microbiome of holobionts have been shown in a variety of animal clades, but studies on teleosts mostly show weak associations. Our study aimed to explore these relationships in four sympatric Serrasalmidae (i.e. piranha) teleosts from an Amazonian lake, using datasets from the hosts genomes (SNPs from GBS), skin and gut microbiomes (16S rRNA metataxonomics), and diets (COI metabarcoding) from the same fish individuals. Firstly, we investigated whether there were significant covariations of microbiome and fish genotypes at the inter and intraspecific scales. We also assessed the extent of co-variation between Serrasalmidae diet and microbiome, to isolate genotypic differences from dietary effects on community structure. We observed a significant covariation of skin microbiomes and host genotypes at interspecific (R2=24.4%) and intraspecific (R2=6.2%) scales, whereas gut microbiomes correlated poorly with host genotypes. Serrasalmidae diet composition was significantly correlated to fish genotype only at the interspecific scale (R2=5.4%), but did not covary with gut microbiome composition (Mantel R=-0.04; only 6 microbiome taxa involved). Secondly, we tested whether microbial taxa represent reliable host traits to complement host genotypic variations in these species. By using an NMDS ordination-based approach, we observed that subsets of the skin and gut microbiomes selected by a machine-learning Random Forest algorithm can complement host genotypic variations by increasing significantly the average interspecific differentiation. The complementarity of genome and microbiome variations suggests that combining both markers could potentially benefit our understanding of the evolution of Serrasalmidae in future studies.
Hybridization plays an important and underappreciated role in shaping the evolutionary trajectories of species. Following the introduction of a non-native organism to a novel habitat, hybridization with a native congener may affect the probability of establishment of the introduced species. In most documented cases of hybridization between a native and a non-native species, a mosaic hybrid zone is formed, with hybridization occurring heterogeneously across the landscape. In contrast, most naturally occurring hybrid zones are clinal in structure. Here we report on a long-term microsatellite dataset that monitored hybridization between the invasive winter moth, Operophtera brumata (Lepidoptera: Geometridae), and the native Bruce spanworm, O. bruceata, over a 12-year period. Our results document one of the first examples of the real-time formation and geographic settling of a clinal hybrid zone. In addition, by comparing one transect in Massachusetts where extreme winter cold temperatures have been hypothesized to restrict the distribution of winter moth, and one in coastal Connecticut, where winter temperatures are moderated by Long Island Sound, we find that the location of the hybrid zone appears to be independent of environmental variables and maintained under a tension model wherein the stability of the hybrid zone is constrained by population density, reduced hybrid fitness, and low dispersal rates. Documenting the formation of a contemporary clinal hybrid zone may provide important insights into the factors that shaped other well-established hybrid zones.
Coevolution is predicted to depend on how the genetic diversity of interacting species is geographically structured. Plant-microbe symbioses such as the legume-rhizobium mutualism are ecologically and economically important, but distinct life history and dispersal mechanisms for these host and microbial partners, plus dynamic genome composition in bacteria, present challenges for understanding spatial genetic processes in these systems. Here we study the model rhizobium Ensifer meliloti using a hierarchically-structured sample of 191 strains from 21 sites in the native range and compare its population structure to that of its host plant Medicago truncatula. We find high local genomic variation and minimal isolation by distance across the rhizobium genome, particularly at the two symbiosis elements pSymA and pSymB, which have evolutionary histories and population structures that are similar to each other but distinct from both the chromosome and the host. While the chromosome displays weak isolation by distance, it is uncorrelated with hosts. Patterns of discordant population structure among elements with the bacterial genome has implications for bacterial adaptation to life in the soil versus symbiosis, while discordant population genetic structure of hosts and microbes might restrict local adaptation of species to each other and give rise to phenotypic mismatches in coevolutionary traits.
Plant pathogens often adapt to plant genetic resistance so characterization of the architecture under-lying such an adaptation is required to understand the adaptive potential of pathogen populations. Erosion of banana quantitative resistance to a major leaf disease caused by polygenic adaptation of the causal agent, the fungus Pseudocercospora fijiensis, was recently identified in the northern Caribbean region. Genome scan and quantitative genetics approaches were combined to investigate the adaptive architecture underlying this adaptation. Thirty-two genomic regions showing host se-lection footprints were identified by pool sequencing of isolates collected from seven plantation pairs of two cultivars with different levels of quantitative resistance. Individual sequencing and phenotyping of isolates from one pair revealed significant and variable levels of correlation be-tween haplotypes in 17 of these regions with a quantitative trait of pathogenicity (the diseased leaf area). The multilocus pattern of haplotypes detected in the 17 regions was found to be highly varia-ble across all the population pairs studied. These results suggest complex adaptive architecture un-derlying plant pathogen adaptation to quantitative resistance with a polygenic basis, redundancy, and a low level of parallel evolution between pathogen populations. Candidate genes involved in quantitative pathogenicity and host adaptation of P. fijiensis were highlighted in genomic regions combining annotation analysis with available biological data.
Many complex healthcare interventions aim to change the behaviour of patients or health professionals, e.g. stopping smoking or prescribing fewer antibiotics. This prompts the question of which behaviour change interventions are most effective. Synthesising evidence on the effectiveness of a particular type of behaviour change intervention can be challenging because of the high levels of heterogeneity in trial design. Here we use data from a published systematic review as a case study and compare alternative methods to address this heterogeneity. One important sources of heterogeneity is that compliance to a desired behaviour can be measured and reported in a variety of different ways. In addition, interventions designed to target behaviour can be implemented at either an individual or group level leading to trials with varying layers of clustering. To handle heterogeneous outcomes we can either convert all effect estimates to a common scale (e.g. using standardised mean differences) or have separate meta-analyses for different types of outcome measure (binary and continuous measures).To address the clustering structure, adjusted standard errors can be used with the inverse variance method, or weights can be assigned based on a consistent level of clustering, such as the number of healthcare professionals. A graphical method, the albatross plot utilises reported p-values only, and can synthesise data with both heterogeneous outcomes and clustering with minimal assumption and data manipulation. Based on these methods, we reanalysed our data in four different ways and have discussed the strengths and weaknesses of each approach.
Objective: To assess the quality of life (QoL) of Cystic fibrosis (CF) patients in West Bank, Palestine using the Cystic Fibrosis Questionnaire-Revised (CFQ-R) form. Method: A cross-sectional study involving application of CFQ-R questionnaire in CF patients attending pediatric pulmonology clinic at Caritas Baby Hospital (CBH). Their health status was assessed by measuring different parameters including pulmonary function test (FEV1) and body mass index (BMI). Results: The sample consisted of 77 patients from 58 families: 46.75% were males. Mean age was 10.7 years. Patients were divided into three groups by age in years: group I (< 6), II (6-13), and III (≥ 14). The highest and lowest CFQ scores were for the eat domain in group III (55.56 ± 22.49) and the body domain in group II (14.48 ± 17.67), respectively. Illness severity as measured by FEV1 mean value 69.6. BMI mean value of 15.998. The overall mean age at time of diagnosis in our sample was 4.16 years (± 6.239). The study showed that 1.7% of families had four affected siblings and 21% had death cases related to CF. Finally, all parameters for CF patients in West Bank, Palestine appear to be noticeably lower than those reported in other countries. Conclusions: quality of life for patients with CF is poor relative to international standards, the medications used including hypertonic saline and Gentamycin IV form used as nebulizer solution are not first line therapies around the world. This study illustrates the need of new therapies for CF patients in Palestine.
Objective: To identify the pathogens and compare the clinical characteristics between different type pathogen infection among children with community-acquired pneumonia (CAP) requiring bronchoalveolar lavage. Study design: Children <14 years old hospitalized with CAP requiring bronchoalveolar lavage were enrolled between February 2019 to January 2020. Multiplex reverse transcription polymerase chain reaction (mRT-PCR) and loop-mediated isothermal amplification (LAMP) were used for pathogen detection. The demographic and clinical characteristics were compared between different type pathogen infection groups. Results: Among 1166 children studied, ≥1 pathogen was detected in 1084 (93.0%) children and co-infection was detected in 215 (18.4%) children. Mycoplasma pneumoniae, Streptococcus pneumoniae and adenovirus were the most frequently detected pathogens. Children infected with atypical bacteria alone were older and more likely to display a fever, cough, decreased breath sounds, consolidation, single lobar infiltration, mucosal erosion and/or necrosis and plastic bronchitis. Children with virus-atypical bacteria co-infection were more prone to manifest fatigue, chest pain, tachypnea, chest indrawing, and mucosal erosion and/or necrosis. Those infected with virus alone or co-infected with ≥3 pathogens were liable to display changes in bronchial morphology. Conclusions: Pathogens were detected in 93.0% of enrolled children. M. pneumoniae infection might be the greatest pediatric disease burden due to CAP in North China. Keywords: Children; community-acquired pneumonia; bronchoalveolar lavage fluid; etiology; co-infection.
Objectives. This study was carried out to delineate the patients’ characteristics and the imaging findings and their relation to some biochemical markers of 31 critically ill patients with MIS-C. Design. A retrospective cross-sectional study including all critically ill MIS-C children admitted to the PICU from June 23rd to July 22nd, 2020. Results. Eighteen males and thirteen females, with a median age of 9 years (interquartile range 6-11) presented mainly with fever (100%) and hypotension (100%). Abnormalities in the chest computed tomography were detected in 22 cases (71%). Consolidation and architecture distortion were detected in 58.1% of patients; bilateral lesions and lower lobe infiltrates, each, were evident in 64.5% , while the peripheral distribution of lesions was seen in 71% of the cases. Pleural thickening and effusion were found in 51.6% of the patients. In this small case series, the presence of high ferritin was significantly associated with the bilaterality of the lesions. Elevated C-reactive protein was associated with the peripheral distribution of the lesions, in addition, thrombocytopenia and hypoalbuminemia were significantly correlated with the CT disease stage and CT severity score respectively. Conclusions. Short and long-term follow up of MIS-C cases is not only needed for the follow up of clinical and laboratory abnormalities but also for the elucidation of the outcome of CT pulmonary findings.