Critical Capacity Research Articles

Neural correlates of transitive inference: An SDM meta-analysis on 32 fMRI studies

Transitive inference (TI) is a critical capacity involving the integration of relevant information into prior knowledge structure for drawing novel inferences on unobserved relationships. To date, the neural correlates of TI remain unclear due to the small sample size and heterogeneity of various experimental tasks from individual studies. Here, the meta-analysis on 32 fMRI studies was performed to detect brain activation patterns of TI and its three paradigms (spatial inference, hierarchical inference, and associative inference). We found the hippocampus, prefrontal cortex (PFC), putamen, posterior parietal cortex (PPC), retrosplenial cortex (RSC), supplementary motor area (SMA), precentral gyrus (PreCG), and median cingulate cortex (MCC) were engaged in TI. Specifically, the RSC was implicated in the associative inference, whereas PPC, SMA, PreCG, and MCC were implicated in the hierarchical inference. In addition, the hierarchical inference and associative inference both evoked activation in the hippocampus, medial PFC, and PCC. Although the meta-analysis on spatial inference did not generate a reliable result due to insufficient amount of investigations, the present work still offers a new insight for better understanding the neural basis underlying TI.

The reorganisation of emergency general surgery services during the COVID-19 pandemic in the UK: outcomes of delayed presentation, socio-economic deprivation and Black, Asian and Minority Ethnic patients.

The COVID-19 pandemic is a global public health emergency. Lockdown restrictions and the reconfiguration of healthcare systems to accommodate an increase in critical care capacity have had an impact on 'non-COVID' specialties. This study characterises the utilisation of emergency general surgery (EGS) services during the UK lockdown period at a university teaching hospital with a catchment population that represents one of the most deprived and ethnically diverse areas in the UK. EGS admissions during the UK lockdown period (March to May 2020) were compared with the same period in 2019. Patient demographics were recorded together with clinical presentation, hospital stay and treatment outcomes, and readmission data. The study included 645 patients, comprising 223 in the COVID-19 period and 422 in the non-COVID-19 period. There was no difference in age, sex, comorbidity or socio-economic status. A lower proportion of patients of Black, Asian and Minority Ethnicity (BAME) were admitted during the pandemic (20.6% vs 35.4%, p<0.05). The duration of symptoms prior to presentation was longer, and admission clinical parameters and serum inflammatory markers. More patients presented with an acute kidney injury (9.9% vs 4.7%, p=0.012). There was no difference in perioperative outcomes or 30-day mortality, but more patients were readmitted following conservative management (10.6% vs 4.7%, p=0.023). The reorganisation of EGS to a senior-led model has been successful in terms of outcomes and access to treatment despite a more unwell population. There was a significantly lower proportion of BAME admissions suggesting additional barriers to healthcare access under pandemic lockdown conditions.

Central-line associated bloodstream infection (CLABSI) in patients hospitalized with COVID-19

Background: Significant increases in healthcare-associated infections (HAIs) including central-line associated blood stream infections (CLABSIs) have been reported during the COVID-19 pandemic. Acute-care hospitals have faced staffing and personal protective equipment shortages, increased critical care capacity, and diversion of resources from traditional HAI surveillance and prevention efforts. In this study, we characterized CLABSIs among patients with COVID-19 and compared demographics, comorbidities, and outcomes between patients diagnosed with CLABSI with and without COVID-19. Methods: This is an observational retrospective cohort study of all patients diagnosed with CLABSI as defined by NHSN at William P. Clements Jr. University Hospital from April 1, 2020, through September 30, 2021. A retrospective chart review was conducted to identify demographics, comorbidities, and outcomes of hospitalized patients diagnosed with CLABSI. Patients hospitalized with and without COVID-19 were compared using the independent-sample t test for means and the χ2 test for proportions. Results: Overall, 82 patients diagnosed with CLABSI between April 1, 2020, to September 30, 2021, among whom 31 (38%) were hospitalized with COVID-19 and 51 (62%) were not hospitalized with COVID-19. Patients hospitalized with COVID-19 were significantly more likely to be obese (58% for COVID-19 positive vs 26% for COVID-19 negative; P = .01) and to require extracorporeal membrane oxygenation (19% vs 4%; P = .04). However, COVID-19 patients were significantly less likely to have hematologic malignancy (7% vs 28%; P = .03), undergone bone marrow transplantation (0% vs 18%; P = .01), or have neutropenia (3% vs 22%; P = .03). There were no significant differences in line type or organism identified. Gram-positive pathogens were identified in 16 patients (52%) hospitalized with COVID-19. Gram-negative pathogens were identified in 3 patients (10%); fungal organisms were identified in 10 patients (32%), and 2 cases (7%) were polymicrobial. Patients with COVID-19 were significantly more likely to require an ICU stay (84% vs 43%). p Conclusions: High device utilization as well as prolonged hospitalization and line days among patients with COVID-19 along are contributing risk factors for CLABSI among patients hospitalized with COVID-19. This finding highlights the need for ongoing HAI surveillance and prevention efforts in patients hospitalized with COVID-19 given their characteristics and increased risk for CLABSI. Reinforcing infection prevention efforts by accentuating the importance of optimal line care and regular feedback are crucial, especially among patients hospitalized with COVID-19.Funding: NoneDisclosures: None

A tree search heuristic for the resource constrained project scheduling problem with transfer times

In this work, we study the resource constrained project scheduling problem with transfer times, where the transfer of resources between activities takes a certain amount of time. For the problem, we propose an improved serial schedule generation scheme, a new lower bound, and a tree search heuristic. To generate a schedule, the improved serial schedule generation scheme iteratively schedules an activity by breaking some existing resource flows and decides the earliest start time in an efficient way. The new lower bound is adapted from the critical capacity lower bound by additionally considering resource transfer times. The tree search heuristic utilizes the improved serial schedule generation scheme to schedule an activity at its earliest start time and the new lower bound to prune unpromising nodes in the search tree. Several priority rules are introduced in the heuristic for the selection of the next activity during branching and also used in a greedy algorithm to compute an upper bound for node evaluation. Computational experiments on benchmark instances show that the improved serial schedule generation scheme reduces the computational time by 91.30% on average compared to an existing serial schedule generation scheme from literature, the new lower bound dominates the known adapted critical path lower bound and achieves an average improvement of 7.95%, and the tree search heuristic performs better than three existing algorithms for the problem.

Modeling transmission of SARS-CoV-2 Omicron in China

Having adopted a dynamic zero-COVID strategy to respond to SARS-CoV-2 variants with higher transmissibility since August 2021, China is now considering whether, and for how long, this policy can remain in place. The debate has thus shifted towards the identification of mitigation strategies for minimizing disruption to the healthcare system in the case of a nationwide epidemic. To this aim, we developed an age-structured stochastic compartmental susceptible-latent-infectious-removed-susceptible model of SARS-CoV-2 transmission calibrated on the initial growth phase for the 2022 Omicron outbreak in Shanghai, to project COVID-19 burden (that is, number of cases, patients requiring hospitalization and intensive care, and deaths) under hypothetical mitigation scenarios. The model also considers age-specific vaccine coverage data, vaccine efficacy against different clinical endpoints, waning of immunity, different antiviral therapies and nonpharmaceutical interventions. We find that the level of immunity induced by the March 2022 vaccination campaign would be insufficient to prevent an Omicron wave that would result in exceeding critical care capacity with a projected intensive care unit peak demand of 15.6 times the existing capacity and causing approximately 1.55 million deaths. However, we also estimate that protecting vulnerable individuals by ensuring accessibility to vaccines and antiviral therapies, and maintaining implementation of nonpharmaceutical interventions could be sufficient to prevent overwhelming the healthcare system, suggesting that these factors should be points of emphasis in future mitigation policies.

Interaction between kink solitary wave and rogue wave, new periodic cross-kink wave solutions and other exact solutions to the (4 + 1)-dimensional BLMP model

In this study, some new solutions to the (4+1)-dimensional Boiti–Leon–Manna–Pempinelli (BLMP) model representing the wave propagation through incompressible fluids. In shallow water, the linearization of the wave structure needs more critical wave capacity conditions than in deep water, and the strong nonlinear features are visible. The obtained solutions may be applied in the demonstration of this model in some better way. These solutions are in the form of interaction between kink solitary wave and rogue wave, new periodic cross-kink wave solutions and other exact solutions with certain conditions. The achieved solutions are also verified by using the latest computational software such as MATHEMATICA. The modified integration techniques, the Hirota bilinear method and the extended (G′/G)-expansion method are utilized to secure the solutions. The obtained solutions are also explained by 3D, 2D and contour graphs. These results may helpful for the further study of the model in future.

Developing Resilience to Disinformation: A Game-Based Method for Future Communicators

This paper analyzes the outcomes of a game-based educational process aiming to strengthen resilience to fake news. An innovative approach that considers linguistic choices as bases for manipulating information is used in an online classroom environment, students in communication being invited to understand, explain and reflect upon framing and information credibility, using as a topic of inquiry the refugee crisis of 2021 in Romania. Cognitive learning outcomes as well as learning dynamics were assessed using pre- and end-of game surveys. The results of the game are discussed in relation with the instructional goal to facilitate the understanding of communicative social actions, learning about disinformation that is deliberately misleading, as well as finding ways to break the disinformation code. The debriefing discussions after each stage of the game encouraged students to reflect upon their newly gained insights and increase their critical thinking capacity, in the effort to ensure a sustainable education in communication studies. The paper has the potential to enrich the educational strategies with innovative methods helping future professionals navigate the complex world of media messages.

Mechanical behavior and mechanism investigation on the optimized and novel bio-inspired nonpneumatic composite tires

Abstract Two novel nonpneumatic tires named Tweel-2, designed based on the commercial Tweel model, and Saddle with hyperbolic paraboloid spokes are proposed in this study. Four nonpneumatic tire samples were successfully prepared with the 3D printing technology to measure and analyze and compare their properties. The results of quasi-static compression experiments showed that with the same relative density, the vertical bearing capacity of Tweel-2 tire was 1.4 times that of Tweel tire, while the vertical bearing capacity of the saddle tire was 4 times and 2.4 times that of Tweel and honeycomb tires, respectively. The finite element simulation method was used to explore the mechanism of improvement in vertical bearing capacity and energy absorption of the Tweel-2 and saddle design. The so-called circumferential unit in Tweel-2 and honeycomb tires enhances the deformation coordination between the spokes of Tweel-2 and increases the critical bearing capacity of the spokes by shortening the length of the deformation zone, so that more external work can be consumed under the same vertical deformation. The spatial configuration of the hyperbolic paraboloid can optimize the spatial stress distribution of the saddle tire and makes sure that a bigger amount of material deforms and participates in energy absorption, thus improving the overall strain energy level of the spokes.

A machine learning and clustering-based approach for county-level COVID-19 analysis.

COVID-19 is a global pandemic threatening the lives and livelihood of millions of people across the world. Due to its novelty and quick spread, scientists have had difficulty in creating accurate forecasts for this disease. In part, this is due to variation in human behavior and environmental factors that impact disease propagation. This is especially true for regionally specific predictive models due to either limited case histories or other unique factors characterizing the region. This paper employs both supervised and unsupervised methods to identify the critical county-level demographic, mobility, weather, medical capacity, and health related county-level factors for studying COVID-19 propagation prior to the widespread availability of a vaccine. We use this feature subspace to aggregate counties into meaningful clusters to support more refined disease analysis efforts.

Case Study of Multi-Course Project-Based Learning and Online Assessment in Electrical Engineering Courses during COVID-19 Pandemic

Due to the COVID-19 pandemic, there was an urgent need to move to online teaching and develop innovative teaching techniques to ensure that student learning outcomes (SOs) were fulfilled. This paper tries to answer the important question of whether an established teaching strategy through a multi-course project-based learning (MPL) approach, along with online assessment techniques, helps in the effective achievement of SOs in a senior-level electrical engineering (EE) course. The authors have developed a course project for attaining the objectives of a senior and a capstone course, where students are registered at the same time. In addition, the course conducts assessments online. The paper reports the effect of the two approaches on the attainment of the SOs of the two courses, along with testing the programming and problem-solving abilities of the students. It is known that the MPL approach enhances the critical thinking capacity of students, which is also a major outcome of Sustainable Development Education (ESD). It was ensured that the project that was used to test the fulfillment of a series of SOs were concentrated on soft engineering and project management skills. The difficulty of adopting the MPL method for the senior-level courses is in the scheduling of the course materials to help the student advance to the final project while also aligning the project towards fulfilling the learning outcomes of the individual course. The study also provides the students with feedback on online assessment techniques incorporated within the MPL. Besides this, the effect of the innovative teaching approaches was compared with the same senior course taught using conventional methods in an earlier semester. Based on the feedback from teachers and students from a previously conducted case study, it was concluded that the MPL approach had supported the student learning. The results of the statistical analysis (Chi-square, two-tailed T statistics and hypothesis testing using a z-test) show that an MPL approach and online assessment improved the attainment of the SOs despite the constraints posed by the pandemic.

Using Outcome Mapping to Mobilize Critical Stakeholders for a Gender Responsive Rift Valley Fever and Newcastle Disease Vaccine Value Chain in Rwanda.

Approximately 752 million of the world's poor keep livestock to produce food, generate income, and build assets. Women represent two-thirds (~400 million people) of low-income livestock keepers. Infectious diseases are a major issue in preventing livestock keepers from optimizing production earnings and improving food security. In Rwanda, highly contagious yet preventable diseases that affect animals that women manage, such as Rift Valley fever in goats and Newcastle disease in chickens have a high-mortality rate and can devastate their herds. Women are disproportionately affected because they bear primary responsibility for goats and chickens. These diseases are preventable through vaccination, but smallholder women farmers rarely benefit from livestock vaccines. Social norms and entrenched cultural stereotypes limit women's confidence and decision-making and restrict their access to resources and information. Women smallholder farmers find that there is little support for the small livestock they manage, because of the official preference given to cattle. They are also challenged by limited availability of livestock vaccines due to lack of a cold chain, inadequate extension, and veterinary services, especially for goats and chickens, and unreliable structures for vaccine delivery. To identify opportunities for women's engagement in the livestock vaccine value chain (LVVC) and reduce their barriers to accessing and using livestock vaccines, we used Outcome Mapping, a stakeholder engagement tool, and the Gender Equality Continuum Tool to classify and engage critical partners in the LVVC. We analyzed each critical partner's capacities, incentives, and drivers for engagement with women, challenges and barriers that hinder their support for women farmers, opportunities at systemic and programmatic levels for women's participation and benefit in the LVVC, and the gender capacities and perceptions of different stakeholders. Enhanced positioning and visibility of women in the LVVC can occur through a systemic engagement of all stakeholders, and recognition of the roles that women play. Women smallholder farmer involvement when determining and shaping the potential entry-points is critical to ensure support for their existing responsibilities in family food security, and future opportunities for generating income. Strengthening gender capacities of LVVC stakeholders, addressing identified barriers, and building on existing opportunities can increase women's participation in the LVVC.

How children revise their beliefs in light of reasons.

We investigate how the ability to respond appropriately to reasons provided in discourse develops in young children. In Study 1 (N=58, Germany, 26girls), 4- and 5-, but not 3-year-old children, differentiated good from bad reasons. In Study 2 (N=131, Germany, 64girls), 4- and 5-year-old children considered both the strength of evidence for their initial belief and the quality of socially provided reasons for an alternative view when deciding whether to change their minds. Study 3 (N=80, the United States, 42girls, preregistered) shows that 4- and 5-year-old children also consider meta-reasons (reasons about reasons) in their belief revision. These results suggest that by age 4, children possess key critical thinking capacities for participating in public discourse.

Performance Characteristics of a Novel 3D-Printed Bubble Intermittent Mandatory Ventilator (B-IMV) for Adult Pulmonary Support.

The COVID-19 pandemic has brought attention to the need for developing effective respiratory support that can be rapidly implemented during critical surge capacity scenarios in healthcare settings. Lung support with bubble continuous positive airway pressure (B-CPAP) is a well-established therapeutic approach for supporting neonatal patients. However, the effectiveness of B-CPAP in larger pediatric and adult patients has not been addressed. Using similar principles of B-CPAP pressure generation, application of intermittent positive pressure inflations above CPAP could support gas exchange and high work of breathing levels in larger patients experiencing more severe forms of respiratory failure. This report describes the design and performance characteristics of the BubbleVent, a novel 3D-printed valve system that combined with commonly found tubes, hoses, and connectors can provide intermittent mandatory ventilation (IMV) suitable for adult mechanical ventilation without direct electrification. Testing of the BubbleVent was performed on a passive adult test lung model and compared with a critical care ventilator commonly used in tertiary care centers. The BubbleVent was shown to deliver stable PIP and PEEP levels, as well as timing control of breath delivery that was comparable with a critical care ventilator.

Het laatste woord in Uphoffs ‘Rotte Boek’

Imagology studies the representation of national identities in (literary) texts, but is usually limited to a cultural-historical and intertextual focus. Hence the textual, ‘aesthetic function’ of literature is often neglected. In this article we argue that the textual analysis of literary techniques, specifically metafiction, can be a useful theoretical impulse for the premises of imagology. This proposed focus also does more justice to (metafictional) literature’s critical capacities regarding the representation of national identities and ‘the other’. This ‘textual’ form of imagology, focused on metafiction, will be applied to the literary representation of a specific European region, the Balkans, in De spelers [The players] (2009) by Manon Uphoff. This novel deals with a love affair between a Dutch woman and a man who fled his native country in response to the violent conflicts that resulted from the disintegration of Yugoslavia in the 1990’s. The representation of Bosnia and Herzegovina in De spelers could be typified as stereotypical or balkanist discourse – a view that was articulated by reviewer Elsbeth Etty in the national paper NRC Handelsblad. We will argue, however, that the self-referential elements of Uphoffs novel have (self-)critical potential with regard to its balkanist representation of Bosnia and Herzegovina.

Experimental Bulging and Buckling of Bi-segmented Cylinders

This paper studies the experimental free bulging and buckling of bi-segmented cylinders. Two cylindrical shells are manufactured using argon-arc welding and analyzed for manufacturing errors. Next, free bulging tests and hydrostatic pressure tests are conducted to verify the feasibility of the free bulging technique and to confirm the destruction form of the bulged bi-segmented barrel. At the same time, the reasonableness of the circular thick plate is examined, which is determined according to the deformation consistency. The results show that the bi-segmented cylindrical preforms exhibit good welding quality by TIG welding technology. It has the same critical pressure load as a single cylindrical preform. Nevertheless, the bi-segmented cylindrical preforms have larger internal volume and better buoyancy capability than the single cylindrical preform. The free bulging bi-segmented shell has good symmetry along the axial direction. It has larger internal volume and higher critical buckle capacities than the non-bulging one.

Portrait of the Emergency Department at Orotta National Referral and Teaching Hospital in Asmara, Eritrea: A Prospective Observational Study.

BackgroundProvision of high-quality emergency care for acute, life-threatening illnesses can significantly reduce DALY and mortality in sub-Saharan Africa. Here, we present data on the profile of an Emergency Department (ED) in the largest referral hospital in Eritrea and potential gaps for intervention.Patients and MethodsThis was a prospective single-center observational study of 1093 patients who presented to the ED between September and October of 2020. Data were collected using a questionnaire from the patients’ interview, observation and medical record review. The data were summarized using descriptive statistics and where applicable logistic regressions were performed.ResultsThe median age was 45.0 years among the patients. In terms of acuity, 741 (68.5%), 283 (26.2%), 48 (4.4%), 10 (0.9%) patients were triaged as green, yellow, red, and black, respectively. In addition, the number of self-referred patients was 857 (79.1%) and among all the visitors, 376 (34.9%) used Ambulance service. The median ± IQR for ED length of stay (LOS) was 2.7 (1.4–10.0) Hours. Further, 154 (14.4%) patients stayed in the ED for >24 hours. The hospitalization rate was 146 (14.7%). In the multivariate analysis, higher likelihood of prolonged ED LOS was observed in: medical department patients (aOR = 3.53, 95% CI = 2.03–6.14); patients referred from primary health-care centers (aOR = 2.63, 95% CI = 1.10–6.30) and hospital (aOR = 3.70, 95% CI = 2.15–6.37). Prolonged ED LOS was also associated with prior emergency visit (aOR = 1.96, 95% CI = 1.13–3.40); consultation (aOR = 12.27, 95% CI = 6.98–21.56); the need for inpatient admission (aOR = 2.34, 95% CI = 1.38–3.96); and the need for investigation and treatment (aOR = 2.03, 95% CI = 1.07–3.85).ConclusionImprovements regarding ED specialist personnel, inpatient ward capacity, availability of investigations throughout the day and night shifts, amendments in referral system, strengthening ED and critical care capacity in zonal referral hospitals, and access to quality care among the non-communicable disease patients may ameliorate most of the bottlenecks observed in this set-up.

Teacher Education Course Design for Improving Pre-service Teachers’ Critical Thinking Ability

&lt;p&gt;社會愈趨複雜，批判思考是人們需要具備的能力之一，師資生是未來的教師，師資培育課程需要提供充分的訓練機會，以引領下一代學生有足夠能力理解社會。本研究以批判思考歷程為基礎，以具有意識形態的議題為教材內容，以結合課中知識理解與課後非同步討論的混成學習策略為教學活動，再以批判思考能力測驗為評量設計，整合設計一門提升批判思考能力之師培課程，再進行一個學期的教學，研究目的在於探討上述課程設計對於師資生的批判思考能力提升之情形，進而確認此課程設計的可行性。本研究根據既有的師培課程內容轉化與發展八個討論議題，並以準實驗研究法之不等組前後測設計進行探究，全程參與者包含實驗組31人和對照組35人，本研究針對實驗組八次的批判思考歷程內容進行等級分析，兩組再進行批判思考能力測驗之前後測對照比較。研究發現實驗組參與者在課中與課後內容的整合以及教育議題討論的參與下，其批判思考能力顯著提升。此課程設計具有合宜性，而建議師培教授在設計批判思考能力的課程時，議題內容選擇、混成學習策略以及符合認知思考歷程的教學活動流程是需要考慮的關鍵要素。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Due to complicated social lives, critical thinking is a critical capacity for people. The training of critical thinking is vital for teacher education students because they themselves will be teachers who can lead students to understand the complicated society. This study constructed a course design regarding critical thinking training based on critical thinking elements, consisting of ideological issues as instructional materials, blended learning with asynchronous dialogue as learning activities, and critical thinking quizzes as learning assessments. The above course was conducted for a semester, and the purpose of this study was to investigate teacher education students&amp;rsquo; ability of critical thinking and to further identify the feasibility of the course design. A quasi-experimental design with a non-equivalent pre-test-post-test&amp;nbsp;design was used to collect data about the rankings of the eight performances on critical thinking issues transformed from the content knowledge of the teacher education course for the experimental group and pre-test and post-test in critical thinking quizzes for the two groups. The experimental group contained 31 students, while the control group contained the other 35 students. This study concluded that the participants promoted their critical thinking ability through the integration of classroom delivery and asynchronous online communication. The course design of this study is feasible and recommended for teacher educators when considering the contents of ideological issues, the activities of blended learning, and the processes of teaching activities based on the transformation of critical thinking cognitive processes when designing a course regarding critical thinking.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

On some new travelling wave structures to the (3+1)-dimensional Boiti-Leon-Manna-Pempinelli model

In this article, the (1G′)-expansion method, the Bernoulli sub-ordinary differential equation method and the modified Kudryashov method are implemented to construct a variety of novel analytical solutions to the (3+1)-dimensional Boiti-Leon-Manna-Pempinelli model representing the wave propagation through incompressible fluids. The linearization of the wave structure in shallow water necessitates more critical wave capacity conditions than it does in deep water, and the strong nonlinear properties are perceptible. Some novel travelling wave solutions have been observed including solitons, kink, periodic and rational solutions with the aid of the latest computing tools such as Mathematica or Maple. The physical and analytical properties of several families of closed-form solutions or exact solutions and rational form function solutions to the (3+1)-dimensional Boiti-Leon-Manna-Pempinelli model problem are examined using Mathematica.

Dimensional crossover of Bose–Einstein condensation of atomic gases in anisotropic harmonic traps

We investigate the dimensional crossover of Bose–Einstein condensation of atomic gases trapped in anisotropic harmonic potentials. The crossover from three dimension to lower dimensions is studied by calculating some thermodynamic quantities, such as critical temperature, heat capacity, entropy and atom number fluctuations in Bose–Einstein condensate. The smooth transition behavior indicates that a decimal dimension may be employed to describe the corresponding intervenient states. We compare the theoretical curves with recent experimental results on the fluctuations of the condensate atom numbers, revealing how the geometry and size of the condensates affect the thermodynamic characteristics.

A novel bioscrubber for the treatment of high loads of ammonia from polluted gas.

This work presents a novel bioscrubber configuration for the treatment of high ammonia loads at short contact times. The biological reactor was designed to work as a moving-bed biofilm rector (MBBR) increasing biomass retention time. This configuration is still unexplored for the treatment of waste gases. Long-term operation of a lab-scale bioscrubber under different inlet concentrations of ammonia (60-570 ppmv) and a gas contact time of 4s was performed to study the system operational limits during 250days. The effect of the dissolved oxygen concentration on the nitrification rate was also evaluated. Under these conditions, a critical elimination capacity (EC) of 250 NH3·m-3·h-1 and a maximum EC of 300g NH3·m-3·h-1 were obtained. The maximum nitrification rate obtained was 0.5kgN·m-3·day-1. However, this nitrification rate only was possible to be achieved under partial nitrification. For complete nitrification, the critical nitrification rate was 0.3kgN·m-3·day-1. These results confirm that bioscrubber coupled to a MBBR is a good alternative to treat high ammonia loads with remarkable advantages, such as the retention of properly biomass concentration without auxiliary equipment.