bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptive sample size determination for the development of clinical prediction models
Authors: Christodoulou Evangelia , Smeden Maarten van , Edlinger Michael , Timmerman Dirk , Wanitschek Maria , Steyerberg Ewout W , Calster Ben Van
Published: October 2020

Background: We suggest an adaptive sample size calculation method for developing clinical prediction models, in which model performance is monitored sequentially as new data comes in. Methods: We illustrate the approach using data for the diagnosis of ovarian cancer (n=5914, 33% event fraction) and obstructive coronary artery disease (CAD; n=4888, 44% event fraction). We used logistic regression to develop a prediction model consisting only of a-priori selected predictors and assumed linear relations for continuous predictors. We mimicked prospective patient recruitment by developing the model on 100 randomly selected patients, and we used bootstrapping to internally validate the model. We sequentially added 50 random new patients until we reached a sample size of 3000, and re-estimated model performance at each step. We examined the required sample size for satisfying the following stopping rule: obtaining a calibration slope ≥0.9 and optimism in the c-statistic (ΔAUC) <=0.02 at two consecutive sample sizes. This procedure was repeated 500 times. We also investigated the impact of alternative modeling strategies: modeling nonlinear relations for continuous predictors, and applying Firth’s bias correction.Results: Better discrimination was achieved in the ovarian cancer data (c-statistic 0.9 with 7 predictors) than in the CAD data (c-statistic 0.7 with 11 predictors). Adequate calibration and limited optimism in discrimination was achieved after a median of 450 patients (interquartile range 450-500) for the ovarian cancer data (22 events per parameter (EPP), 20-24), and 750 patients (700-800) for the CAD data (30 EPP, 28-33). A stricter criterion, requiring ΔAUC <=0.01, was met with a median of 500 (23 EPP) and 1350 (54 EPP) patients, respectively. These sample sizes were much higher than the well-known 10 EPP rule of thumb and slightly higher than a recently published fixed sample size calculation method by Riley et al. Higher sample sizes were required when nonlinear relationships were modeled, and lower sample sizes when Firth’s correction was used. Conclusions: Adaptive sample size determination can be a useful supplement to a priori sample size calculations, because it allows to further tailor the sample size to the specific prediction modeling context in a dynamic fashion.
Influence of Convalescent Plasma Therapy on the Mortality in COVID-19 Patients: A Meta-Analysis
Authors: Liu Xingxiang , Wu Jing , Zhang Yuanyuan , Dong Chen
Published: October 2020

As of August15, 2020, more than 21,155,600 people were infected and about 761,264 were expired due to SARS-CoV-2 infection worldwide. The extreme spread of the emerging virus makes the disease a serious problem for public health. However, a curative treatment or effective specific vaccine againstSARS-CoV-2 infection is unavailable. Recently, several studies have been performed to evaluate the effects of COVID-19 convalescent plasma transfusion on the clinical outcomes in patients with severe/critical COVID-19 [1-5]. However, the results from these studies aredatable, and thus its useremains investigational.
A New Optical Coherence Tomography Method for Subfoveal Choroidal Thickness Measurement: A Single-center Observational Study
Authors: Kang Kyung Tae , Jang Ji Hye , Kim Yu Cheol
Published: October 2020

Background: Several macular pathologies are associated with choroidal vascular supply, and thus require choroidal thickness evaluation. However, there is no standard subfoveal choroidal thickness (SFCT) measuring method. This study investigated a new method to measure the SFCT, using optical coherence tomography.Methods: This is a single-center observational study. Eighty-two senior medical students participated as observers and independently measured the SFCT on five standard optical coherence tomography images of healthy adults in a tertiary care setting. They used three different methods: (1) the observer’s own method, (2) the conventional method, perpendicular to the retinal pigment epithelium, and (3) the new method, along a virtual line connecting the umbo with the most elevated point of the ellipsoid. Additionally, the SFCT angle—the angle between the measurement line and the vertical line of the image—was measured and compared between methods. The intraclass correlation coefficient was used to determine interpersonal variability. Results: The intraclass correlation coefficients for SFCT measured by methods 1, 2, and 3 were 0.853, 0.880, and 0.896, respectively (P < 0.001 for all). It was the highest with method 3; the intraclass correlation coefficients SFCT angles were 0.647, 0.842, and 0.307, respectively (P < 0.001 for all).Conclusions: The new method showed the lowest interpersonal variability, and could therefore be a reliable standard for SFCT measurement, even in foveae with a steep slope on optical coherence tomography.Trial registration: Not applicable
Treatment of Hepatocellular Carcinoma-associated Portal Vein Tumor Thrombus Using Combination of Portal Vein Stent Insertion and Endovascular Lodine-125 Seed-strip Implantation Followed by Transcatheter Arterial Chemoembolization- Sorafenib
Authors: Li Shuangxi , Li Baohua , Li Lei , Xu Fangyu , Yang Xujun , Wang Wenhui
Published: October 2020

BackgroundTo evaluate the efficacy of portal vein stent (PVS) insertion and endovascular iodine-125 (125I) seed-strip implantation followed by transcatheter arterial chemoembolization (TACE)-sorafenib (PVS-125I-TACE-S) in patients with hepatocellular carcinoma (HCC)-associated portal vein tumor thrombus (PVTT).MethodsThis retrospective analysis was performed on 53 consecutive HCC patients with PVTT between May 2014 and July 2018. Twenty-eight patients were treated via PVS-125I-TACE-S, and 25 patients were treated by TACE-S. Hepatic function, disease control, and overall survival (OS) in both groups were analyzed. The Albumin-Bilirubin (ALBI) score approach was used as a means of evaluating liver function, and a Cox regression analysis was utilized to determine which factors were linked to treatment outcomes.ResultsNo preoperative differences in ALBI scores between groups (P=0.724), nor did these scores at 1-month postoperative (P=0.666). However, these scores were significantly different at 3 (P=0.007) and 6 (P=0.044) months postoperatively. PVS-125I-TACE-S exhibiting higher rates of disease control (71.4% vs. 44.0%, P=0.043) after 6 months of treatment and extended OS duration (342.0 vs 231.0 days, P=0.007). A stratified analysis revealed OS in patients with type II PVTT did not differ significantly (313.0 vs. 321.0 days, P=0.689), but OS with type III did (344.0 vs. 226.0 days, P=0.002). A multivariate analysis revealed that tumor size > 10 cm was independently predictive of poor prognosis (P=0.002), whereas PVS-125I-TACE-S was a predictor of a favorable patient prognosis (P=0.040).ConclusionPVS-125I-TACE-S represents a potentially viable strategy for improving hepatic functionality, disease control, and OS in HCC with type III PVTT.
Toe flexor strength and foot morphology in older people requiring long-term care due to changes in their means of mobilizing in daily life: a cross-sectional study
Authors: Yokozuka Mieko , Sato Sei
Published: October 2020

Background: Hallux valgus and lesser toe deformity reduce the strength of the toe flexors and are a cause of falls in older people. This study aimed to examine the differences in toe flexor strength and foot morphology in older people requiring long-term care due to changes in the way they mobilize in everyday life.Methods: Eighty-four people aged ≥70 without motor paralysis who are undergoing or had undergone ambulatory rehabilitation. They were divided into those who could mobilize without a wheelchair (walking group, n=54) and those who used a wheelchair to mobilize (wheelchair group, n=30). Presence of diseases, hand grip strength, toe flexor strength, and foot morphology were compared between the two groups.Results: No significant between-group difference in foot morphology was found. Factors related to differences in the means used to mobilize in daily life were a history of fracture, heart disease, and toe flexor strength. In muscle strength of the wheelchair group compared with the mean values of the walking group, the toe flexor strength was significantly more decreased in relation to hand grip strength.Conclusions: Older people who use a wheelchair to mobilize have significantly less toe flexor strength than those who do not despite having no significant difference in foot morphology. Use of a wheelchair is associated with a reduction in toe flexor strength.
Safety measures for COVID-19 do not compromise the outcomes of patients undergoing primary percutaneous coronary intervention: A single center study
Authors: Guan Xiaonan , Zhang Jianjun , Li Yanbing , Ma Ning
Published: October 2020

Coronavirus disease 2019 (COVID-19) is a global pandemic impacting nearly 170 countries/regions and millions of patients worldwide. Patients with acute myocardial infarction (AMI) still need to be treated at percutaneous coronary intervention (PCI) centers with relevant safety measures. This study was conducted to assess the therapeutic outcomes of PCI performed under the safety measures and normal conditions. AMI patients undergoing PCI between January 24 to April 30, 2020 were performed under safety measures for COVID-19. Patients received pulmonary computed tomography (CT) and underwent PCI in negative pressure ICU. Cardiac catheterization laboratory (CCL) staff and physicians worked with level Ⅲ personal protection. Demographic and clinical data, such as door-to-balloon (DTB) time, operation time, complications for patients in this period (NCP group) and the same period in 2019 (2019 group) were retrieved and analyzed. NCP and 2019 groups had 37 and 96 patients, respectively. There was no significant difference in age, gender, BMI and comorbidity between the two groups. DTB time and operation time were similar between the two groups (60.0 ± 12.39 vs 58.83 ± 12.85 min, p = 0.636; 61.46 ± 9.91 vs 62.55 ± 10.72 min, p = 0.592). Hospital stay time in NCP group was significantly shorter (6.78 ± 2.14 vs 8.85 ± 2.64 days, p < 0.001). The incidences of malignant arrhythmia and Takotsubo Syndrome in NCP group were higher than 2019 group significantly (16.22% vs 5.21%, p = 0.039; 10.81% vs 1.04% p = 0.008). During hospitalization and 3-month follow-up, the incidence of major adverse cardiovascular events and mortality in the two groups were statistically similar (35.13% vs 14.58%, p = 0.094; 16.22% vs 8.33%, p =0.184). Our analysis showed that safety measures undertaken in this hospital, including screening of COVID-19 infection and use of personal protection equipment for conducting PCI did not compromise the surgical outcome as compared with PCI under normal condition, although there were slight increases in incidence of malignant arrhythmia and Takotsubo Syndrome.
African Americans and European Americans exhibit distinct gene expression patterns across tissues and tumors that are associated with immunologic and infectious functions and environmental exposures
Authors: Singh Urminder , Hernandez Kyle , Aronow Bruce , Wurtele Eve
Published: October 2020

The COVID-19 pandemic has affected African American populations disproportionately with respect to prevalence, morbidity, and mortality. Because gene expression profiles represent combined genetic, socioenvironmental, and physiological effects, and could provide therapeutic biomarkers and environmental mitigation strategies, we undertook a large-scale assessment of differential gene expression between African Americans and European Americans. To do this, we mined RNA-Seq datasets from normal and diseased (tumor) conditions whose metadata could be used to evaluate differential patterns. We observed widespread differential expression of genes implicated in COVID-19 and integral to epithelial boundary function, inflammation, infection, and reactive oxygen stress. Notably, expression of the little-studied F8A2 gene is up to 40-fold greater in African
Americans. F8A2, like F8A1, encodes HAP40 protein, which mediates early endosome movement. African American gene expression signatures reveal increased number or activity of esophageal glandular cells and lung ACE2-positive basal keratinocytes. These findings have potential to establish prognostic signatures, refine approaches to minimizing risk of severe infection, and improve precision treatment of COVID-19.
Towards Health System Resiliency: An Agile Systems Modelling Framework for Bed Resource Planning During COVID-19
Authors: Lam Shao Wei Sean , Abdullah Hairil Rizal Bin , Pourghaderi Ahmad Reza , Nguyen Ngoc Hoang Long , Wu Jun Tian , Mohan Somesh Dev S/O , Low Seng Kee , Lee Jiunn Kee , Tan Bo Ren , Han Songhan , Chong Zhi Ying Brendan , Siddiqui Fahad Javaid , Ansah John Pastor , Low G Jenny , Matchar David Bruce , Ong Eng Hock Marcus
Published: October 2020

Background: We describe the development of a dynamic simulation modelling framework to support agile resource planning during the COVID-19 pandemic. The framework takes into consideration the dynamic evolution of the pandemic and the rapidly evolving policies and processes to deal with the ever-changing outbreak scenarios.Methods: A specific use case based on short-term bed resource planning is described within the proposed framework. The simulation model was calibrated against historical data for the Singapore COVID-19 situation. The time period for model calibration was from 1st April till 30th April 2020. The model was used to project for bed resource needs over the period from 1st May 2020 till 31st May 2020. Multivariate sensitivity analysis was also conducted for ICU and general isolation bed demand, length-of-stay (LOS), and age-adjusted conversion rates across different care needs. The unmet needs under various scenarios were also evaluated for planning purposes.Results: Several variants of the agile resource planning model were developed to adapt to the fast-changing COVID-19 situation in Singapore. The use case demonstrated an agile adaptation of the model to account for previously unexpected scenarios. The rapid evolution of the pandemic locally revealed streams of new infections that arose from two distinct sources. The model projections were calibrated with the latest data for short-term projections. The agility in flexing plans and collaborative management structures to rapidly deploy human and capital resources to surge the level of care during the COVID-19 pandemic have proven utility in guiding the allocation of scarce healthcare resources and helped system resiliency.Conclusions: The rapidly evolving COVID-19 pandemic in Singapore has necessitated the development of an agile and adaptable modelling framework that can be quickly calibrated to changes both from demand and supply. The modelling framework is able to deploy systems modelling concepts in a holistic manner. This facilitates the evaluation of complex cause-and-effect relationships. A robust collaborative framework, coupled with the availability of in-depth domain knowledge and accurate and updated data availability ensures a model is realistic, timely and useful.
SARS-CoV-2 historical global testing and genomic variability
Authors: Tannous Halim , Akiki Shadi , Boulos Rasha E. , Eid Charlene El Khoury , Hasbani Ghadi El , Khoueiry Lea Maria , Khoury Lynn El , Tohme Rawan , Moussa Rim , Khazen Georges
Published: October 2020

The world has been dealing with the COVID-19 pandemic since December 2019 and a lot of effort has focused on tracking the spread of the virus by gathering information regarding testing statistics and generating viral genomic sequences. Unfortunately, there is neither a single comprehensive resource with global historical testing data nor a centralized database with summary statistics of the identified genomic variants.We merged different pre-aggregated historical testing data and complemented them with our manually extracted ones, which consist of 6852 historical test statistics from 76 countries/states unreported in any other dataset, at the date of submission, making our dataset the most comprehensive to date. We also analyzed all publicly deposited SARS-CoV-2 genomic sequences in GISAID and annotated their variants. Both datasets can be accessed through our interactive dashboard which also provides important insights on different outbreak trends across countries and states.The dashboard is available at https://bioinfo.lau.edu.lb/gkhazen/covid19. A daily updated version of the datasets can be downloaded from github.com/KhazenLab/covid19-data.
Screening Newly Developed Bermudagrasses for Host Plant Resistance against Fall Armyworm (Lepidoptera: Noctuidae)
Authors: Singh Gurjit , Joseph Shimat V. , Schwartz Brian
Published: October 2020

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important pest of warm-season turfgrass species, including bermudagrass (Cynodon spp.). Bermudagrass is a popular turfgrass that is widely planted on golf courses, athletic grounds, and ornamental landscapes across the country and throughout the world. Spodoptera frugiperda infestation is often sporadic; however, when it does occur, damage can be severe. Host plant resistance against S. frugiperda can be a valuable tool for reducing or preventing the use of insecticides. Therefore, the objective of this study was to determine resistance against S. frugiperda in a few promising bermudagrasses. Fourteen experimental bermudagrass genotypes plus two control cultivars, ‘Zeon’ zoysiagrass (resistant control) and ‘TifTuf’ bermudagrass (susceptible control), were evaluated against S. frugiperda to determine host plant resistance in the laboratory. The results showed that the resistant control, ‘Zeon’ zoysiagrass, was more resistant than the other genotypes to S. frugiperda larvae. To determine the response of the experimental lines to S. frugiperda as compared with that of the controls, three indices were developed based on survival, development, and overall susceptibility. According to the susceptibility index, ‘13-T-1032’, ‘T-822’, ‘11-T-510’, ‘12-T-192’, ‘11-T-56’, ‘09-T-31’, ‘11-T-483’, and ‘13-T-1067’ were the top-ranked bermudagrasses. Among these, the responses of ‘13-T-1032’, ‘T-822’, ‘11-T-510’, ‘11-T-56’, ‘09-T-31’, and ‘11-T-483’ were comparable to that of ‘TifTuf’, and antibiosis was the underlying mechanism of resistance. Additionally, larval length, head capsule width, and weight were negatively associated with the days of pupation and adult emergence and positively associated with pupal length, thorax width, and weight. These results will help refine future breeding and with investigations of resistance against the fall armyworm.
The correlation analysis between ant mounds and plant resource in Olkhon region
Authors: Wang Xu , Hu Qingxi , Kong Weizheng , Zhang Chenyang , Jia Shan , Chang Yuan , Deng Wei , Lishtva A. V. , Shilenkov V. G. , Li Zhongqiu , Tian Xingjun
Published: October 2020

Olkhon region in East Siberia has abundant and unique vegetation and animal resource for its peculiar geographic location, including ants. Ant, recognized as ecosystem engineers, has an important role in ecosystem. In order to investigate the ecological role of mound-building ants in this region, we focused our attention on the correlation between the distribution of ant mounds and plant species. Five quadrats (5 m × 5 m) were set up in this region, each of which was then divided into twenty-five quadrats (1 m × 1 m). We collected the location of every Black Bog Ant (Formica candida) mound, the number and biomass of various plants in every small quadrat. Using matrices, we tested the distribution pattern of ant mound randomly. The correlation between plants and ant mound pattern was tested by correlation analysis and regression analysis. The result showed that the spatial distribution of ant mound was random. We also found that Artemisia frigida, Carexduriuscula and Oxytropis sylvesfris had a significant linear relationship with the spatial distribution of ant mound (P < 0.05), suggesting that the spatial distribution of ant mound was dependent on the spatial distribution of some plants. The underlying mechanism was further studied. We attributed this correlation to the feeding habits and foraging strategies of Black Bog Ant and tissue structure of these three plants. Our study figured out the interaction between Black Bog Ant and plant resource in Olkhon region, laying down the foundation for future study on the co-evolution of plant and animal resource in this unique ecosystem.
Ultra-reduced phases in ophiolites cannot come from Earth’s mantle
Authors: Ballhaus Chris , Helmy Hassan M. , Fonseca Rául O.C. , Wirth Richard , Schreiber Anja , Jöns Niels
Published: October 2020

Several recent papers have purported to find ultra-reduced minerals—as natural examples—within ophiolitic mantle sections, including SiC moissanite, Fe-Si alloys, various metal carbides, nitrides, and borides. All those phases were interpreted to be mantle derived. The phases are recovered from mineral concentrates and are assigned to the deep mantle because microdiamonds and other ultrahigh-pressure (UHP) minerals are also found. Based on these findings, it is claimed that the mantle rocks of ophiolite complexes are rooted in the transition zone (TZ) or even in the lower mantle, at redox states so reduced that phases like SiC moissanite are stable.

We challenge this view. We report high-temperature experiments carried out to define the conditions under which SiC can be stable in Earth’s mantle. Mineral separates from a fertile lherzolite xenolith of the Eifel and chromite from the LG-1 seam of the Bushveld complex were reacted with SiC at 1600 K and 0.7 GPa. At high temperature, a redox gradient is quickly established between the silicate/oxide assemblage and SiC, of ~12 log-bar units in fO2.

Reactions taking place in this redox gradient allow us to derive a model composition of an ultra-reduced mantle by extrapolating phase compositions to 8 log units below the iron-wüstite equilibrium (IW-8) where SiC should be stable. At IW-8 silicate and oxide phases would be pure MgO end-members. Mantle lithologies at IW-8 would be Fe° metal saturated, would be significantly enriched in SiO2, and all transition elements with the slightest siderophile affinities would be dissolved in a metal phase. Except for the redox-insensitive MgAl2O4 end-member, spinel would be unstable. Relative to an oxidized mantle at the fayalite-magnetite-quartz (FMQ) buffer, an ultra-reduced mantle would be enriched in enstatite by factor 1.5 since the reduction of the fayalite and ferrosilite components releases SiO2. That mantle composition is unlike any natural mantle lithology ever reported in the literature. Phases as reduced as SiC or Fe-Si alloys are unstable in an FeO-bearing, hot, convecting mantle. Based on our results, we advise against questioning existing models of ophiolite genesis because of accessory diamonds and ultra-reduced phases of doubtful origin.
Geometry of variational methods: dynamics of closed quantum systems
Authors: Hackl Lucas , Guaita Tommaso , Shi Tao , Haegeman Jutho , Demler Eugene , Cirac Ignacio
Published: October 2020

We present a systematic geometric framework to study closed quantum systems based on suitably chosen variational families. For the purpose of (A) real time evolution, (B) excitation spectra, (C) spectral functions and (D) imaginary time evolution, we show how the geometric approach highlights the necessity to distinguish between two classes of manifolds: Kähler and non-Kähler. Traditional variational methods typically require the variational family to be a Kähler manifold, where multiplication by the imaginary unit preserves the tangent spaces. This covers the vast majority of cases studied in the literature. However, recently proposed classes of generalized Gaussian states make it necessary to also include the non-Kähler case, which has already been encountered occasionally. We illustrate our approach in detail with a range of concrete examples where the geometric structures of the considered manifolds are particularly relevant. These go from Gaussian states and group theoretic coherent states to generalized Gaussian states.
Density resolved wave packet spreading in disordered Gross-Pitaevskii lattices
Authors: Kati Yagmur , Yu Xiaoquan , Flach Sergej
Published: October 2020

We perform novel energy and norm density resolved wave packet spreading studies in the disordered Gross-Pitaevskii (GP) lattice to confine energy density fluctuations.
We map the locations of GP regimes of weak and strong chaos subdiffusive spreading in the 2D density control parameter space and observe strong chaos spreading over several decades.
We obtain a renormalization of the ground state due to disorder, which allows for a new disorder-induced phase
of disconnected insulating puddles of matter due to Lifshits tails. Inside this Lifshits phase, the wave packet spreading is substantially slowed down.
Management innovation practices to public sector organizations
Authors: Zidonis Zilvinas , Bilinskyi Dmytro , Nazyrov Karim
Published: October 2020

The journey of modern management ideas to the public sector in post-socialist countries is expected to be hampered by several barriers. This paper aims to justify the need to implement management innovation practices for public sector organizations. The study was conducted using the method of typological analysis to determine the organization of managerial innovations; modeling method to determine the conceptual model and the position of the travel of management ideas to the country. As a result, a conceptual model was proposed, including elements of the internal and external control environment. Conclusions are given on the barriers that affect the choice and acceptance of management ideas. The article extends current research understanding of man-agreement innovation in the public sector in the region by specifically addressing the success, or failure, of the travel of modern management ideas to it and outlines key barriers to modern management adoption ideas in the public sector. AcknowledgmentThe research was funded by the Lithuanian Council of Research grant S-MOD-17-15.
Konsistensi Nahdlatul Ulama’ dalam Mempertahankan Pancasila dan Kedaulatan Negara Kesatuan Republik Indonesia di tengah Wacana Negara Islam
Authors: Farih Amin
Published: October 2020

Since its establishment, NU has always prioritized the interests of the nation and state based on Islamic shari'a and Islamic values, Indonesianism and has a high spirit of nationalism. By using qualitative research and historical methods, this article comprehensively describes how NU, as one of the largest CSOs in Indonesia has its own way of placing roles and realizing its contribution in upholding the concept of Pancasila and maintaining the sovereignty of Indonesia in the frame of the Unitary State. Republic of Indonesia (NKRI). The results of this study explain that NU refused to firmly reject the idea of khilafah and the concept of an Islamic State in Indonesia, this attitude has been shown by NU by rejecting the presence of the Indonesian Islamic State (NII) founded by Kartosuwiryo. This attitude of rejection of the concept of khilafah was also indicated by the attitude of NU's (Nahdlatul Ulama’) recognition that decided the position of the Head of State of the Republic of Indonesia (Ir. Sukarno) as wāliy al-amri al-ḍarūri bi al-shawkah or de facto with full power in the NU Ulema Alim National Conference in Cipanas in 1954 and the 20th NU Congress Decision in Surabaya, 8-13 September 1954. The consistency of the attitude pointed out by NU continued in the New Order and until the reform era, now to keep rejecting the khilafah system.
Impacts of bias nonstationarity of climate model outputs on hydrological simulations
Authors: Hui Yu , Xu Yuni , Chen Jie , Xu Chong-Yu , Chen Hua
Published: October 2020

Bias correction methods are based on the assumption of bias stationarity of climate model outputs. However, this assumption may not be valid, because of the natural climate variability. This study investigates the impacts of bias nonstationarity of climate models simulated precipitation and temperature on hydrological climate change impact studies. The bias nonstationarity is determined as the range of difference in bias over multiple historical periods with no anthropogenic climate change for four different time windows. The role of bias nonstationarity in future climate change is assessed using the signal-to-noise ratio as a criterion. The results show that biases of climate models simulated monthly and annual precipitation and temperature vary with time, especially for short time windows. The bias nonstationarity of precipitation plays a great role in future precipitation change, while the role of temperature bias is not important. The bias nonstationarity of climate model outputs is amplified when driving a hydrological model for hydrological simulations. The increase in the length of time window can mitigate the impacts of bias nonstationarity for streamflow projections. Thus, a long time period is suggested to be used to calibrate a bias correction method for hydrological climate change impact studies to reduce the influence of natural climate variability.
Microbiological evaluation of constructed wetlands and solar disinfection in wastewater treatment and reuse
Authors: Santos Vinícius B. , Machado Beatriz S. , Atalla Alexandre , Cavalheri Priscila S. , Magalhães Filho Fernando J. C.
Published: October 2020

The objective of this study was to evaluate the removal of fecal indicator bacteria and select bacterial pathogens (total coliforms, Escherichia coli, Shigella spp., Salmonella spp. and Pseudomonas aeruginosa) in vertical flow constructed wetlands (VF-CWs) with earthworms and solar disinfection (SODIS) as post-treatment of effluent from a septic tank. There was no significant difference between them in removing bacteria using a VF-CW with earthworms (VF-CW W/E) and without earthworms (VF-CW N/E). Both VF-CWs did not completely remove pathogens; however, with the SODIS technology receiving the effluent from VF-CW W/E, for E. coli, Shigella spp., Salmonella spp. and P. aeruginosa, the values were reduced below the limit of detection and 4.3 log unit average reduction for total coliforms, with 6 h in SODIS.
Optimum contributions of hydropower reservoirs to the minimum flow of Vu Gia – Thu Bon river basin
Authors: Thang To Viet , Thu Nga Nguyen T. , Le Long Ngo
Published: October 2020

Upstream hydropower development has a great impact on downstream flows. According to the Regulation of Multi-reservoir Operation in Vu Gia – Thu Bon River Basin (Regulation 15371), four large-scale upstream reservoirs must discharge certain flow during the dry season to increase water levels at downstream hydrological stations named Ai Nghia and Giao Thuy. These stations are used as the control points for the downstream water supply. An optimizing-simulation based model was developed that both maximizes total electricity production and ensures minimum flow downstream as required. A thousand combinations of the reservoir inflows were generated by Monte Carlo simulation, considering the correlation between tributaries. Then, the Scatter search algorithm available in the Optquest module of Crystal Ball was used to find the optimal release from the reservoirs. The results show that the current Regulation 1537 can be improved for more efficient water resources management.
Medium- and long-term runoff forecasting based on a random forest regression model
Authors: Shijun Chen , Qin Wei , Yanmei Zhu , Guangwen Ma , Xiaoyan Han , Liang Wang
Published: October 2020

Medium- and long-term runoff forecasting is closely related to the generation capacity forecasting of cascade hydropower stations, which is of great significance to power plants when arranging production plans and assisting market decisions. In order to improve the accuracy of runoff forecasting, an attempt was made to use random forest regression (RFR) to model the medium- and long-term runoff forecasting and to further make a verification based on the actual monthly runoff data of Mupo and Chuntangba stations. By comparison with the forecast results attained through a support vector machine (SVM) and an integrated autoregressive moving average model (IARMA), the results showed that the RFR model had the lowest mean square error (MSE) among the three methods. In addition, the coefficients of determination R2 of the RFR for the two stations increased by 0.0261 and 0.0295 compared with the SVM model, and the R2 rose by 0.1134 and 0.1332 compared with the IARMA model. The comparison of the three methods showed that the RFR had higher forecasting accuracy as well as stronger reliability and practicability than the IARMA model and the SVM model, so the RFR provided a new idea and method for the study of runoff forecasting.
Feasibility of water desalination for irrigation: the case of the coastal irrigated area of Dyiar-Al-Hujjej, Tunisia
Authors: Daghari Issam , El Zarroug Mohamed Ramadhane , Muanda Charles , Kompany Jean Robert , Kanzari Sabri , Mimoun Anouar Ben
Published: October 2020

Irrigation in Tunisia is threatened all over the country. The irrigated coastal area of Dyiar-Al-Hujjej has observed a drop in agricultural activity following a seawater intrusion. Thus, yields have become disrupted in direct relation to the quantities of fresh water supplied and transferred over a distance of 100 km. For the sustainability of this area, the feasibility of using desalinated water to stabilize the irrigation water supply was analyzed. When all crop water requirements are to be met with desalinated water, the net income is negative for crops currently grown, except strawberry. All the open-field crops remain unprofitable even in the case of agro-industrial development, except tomatoes. A blending between desalinated seawater and aquifer saltwater also leads to a negative income for the main crops. The introduction of greenhouses to replace the same open-season crops is beneficial when desalinated water is used. The use of desalinated water in irrigation faces the high cost of desalination (0.5 US $/m3) while the average price of irrigation water in Tunisia is 0.05 US $/m3. Desalination can be recommended only in the case of crops with low need for water and high added value.
Optimization of preparation of montmorillonite nanometer zero-valent iron and the degradation of amoxicillin by response surface methodology
Authors: Sun Guangyin , Zhang Jiankun , Meng Wei , Wang Liping
Published: October 2020

Three-factor and three-level tests were carried out by Box–Behnken response surface methodology, with amoxicillin as the target pollutant, nanometer zero-valent iron (nZVI) materials loaded with montmorillonite prepared by liquid phase reduction method and the concentration of FeSO4 and NaBH4 and montmorillonite dosage as influencing factors. It revealed that the interaction between FeSO4 concentration and NaBH4 concentration had a significant effect on the preparation of montmorillonite-loaded nanometer zero-valent iron material, playing a key role in the removal of amoxicillin, and the effect of FeSO4 concentration was even more significant. In addition, the shape, structure and characteristic groups of the prepared materials were analyzed by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), etc. The nanometer zero-valent iron loaded with montmorillonite can effectively slow down the nZVI agglomeration effect and improve the effect of material degradation of pollutants. For the same concentration of amoxicillin wastewater, the removal rate of amoxicillin wastewater, after 1 h reaction, is as follows: Mont/nZVI > nZVI > Mont. The optimal conditions for the reaction are: pH is 3, the initial concentration is 60 mg/L, and the dosage is 2 g/L. The higher the temperature, the more amoxicillin is degraded by Mont/nZVI.
Determination on inhibition effects of coagulants used in wastewater treatment plants on anaerobic digester
Authors: Demirkol Güler Türkoğlu , Balcıoğlu Gökhan , Öz Nurtaç , Elnekave Moiz , Armağan Bülent , Tüfekci Neşe
Published: October 2020

Domestic wastewaters causing pollution contain inorganic and/or organic materials. When the domestic wastewater outflows to the receiving waters, it causes physical, chemical, and biological pollution in them, and deteriorates the ecological balance of those waters. In the treatment of wastewater, various treatment methods are available depending on the pollution strength of the wastewater. Besides mechanical and biological methods, wastewater treatment with physicochemical methods is still one of the most effective and economical options. Particularly in wastewater with a high concentration of suspended solids, this method is very successful, and obtaining high suspended solids removal efficiencies is very possible. In this study, the effects of the use of coagulant and coagulant aid to be used in a treatment plant where domestic wastewater treatment is carried out are determined to increase the treatment efficiency of a biological treatment that comes later in the stages of the treatment. The effluent of the pre-settling tank may contain a lot of suspended solids. This presence of excess suspended solids decreases the efficiency at other levels of treatment and causes energy loss. In the experiments, the standard jar and inhibition tests are done as a method. As a result of the conducted studies, it is determined that the FeCl3, Synthetic coagulant LP 526, FeClSO4, and the combination of anionic polyelectrolyte yield the best results in the removal of the parameters of chemical oxygen demand (COD), total suspended solids (TSS), and volatile suspended solids (VSS). While FeCl3, APE 65, APE 85, Synthetic coagulant LP 526, and FeClSO4 did not show any inhibition effect in the sludge, APE 67, CPE 84, and (Al2(SO4)3 are found to cause inhibition in the sludge.
Bibliometric approach to the perspectives and challenges of membrane separation processes to remove emerging contaminants from water
Authors: Stefanello Cadore Jéssica , Fabro Lucas Fernando , Garcia Maraschin Thuany , de Souza Basso Nara Regina , Rodrigues Pires Marçal José , Barbosa Brião Vandré
Published: October 2020

The presence of contaminants in water is concerning due to the potential impacts on human health and the environment, and ingested contaminants cause harm in various ways. The conventional water treatment systems are not efficient to remove these contaminants. Therefore, novel techniques and materials for the removal of contaminants are increasingly being developed. The separation process using modified membranes can remove these micropollutants; therefore, they have attracted significant research attention. Among the materials used for manufacturing of these membranes, composites based on graphene oxide and reduced graphene oxide are preferred owing to their promising properties, such as mechanical resistance, thermal and chemical stability, antifouling capacity, water permeability, high thermal and electrical conductivity, high optical transmittance and high surface area. Membrane separation processes (MSP) can be used as secondary or tertiary treatment during the supply of wastewater. However, the efficient and accessible applications of these technologies are challenging. This study aims to demonstrate the main concepts of membrane separation processes and their application in the removal of emerging contaminants. This study reports bibliometric mapping, relevant data on studies using membranes as water treatment processes, and their viability in industrial applications. The main challenges and perspectives of these technologies are discussed in detail as well.
Adsorption behavior of Fe (III) in aqueous solution on melamine
Authors: Peng Hao , Guo Jing , Wang Bingqing
Published: October 2020

This paper focused on the adsorption behavior of Fe (III) in aqueous solution on melamine. The effects of experimental conditions including dosage of melamine, reaction time and reaction temperature were investigated. The results showed that nearly 99% Fe (III) was adsorbed under the optimal conditions: melamine dosage (mole ratio) at n(C3H6N6)/n(Fe) = 3.5:1, reaction time of 60 min and reaction temperature of 90 °C. The optimal processing factors were obtained from response surface methodology and the effects of processing parameters on the removal efficiency of Fe (III) followed the order: mole ratio (n(C3N6H6):n(Fe)) > reaction temperature > reaction time. The adsorption kinetics behavior was fitted well with the pseudo-second-order model. The thermodynamic study showed that the adsorption process was unspontaneous and endothermic. The value of free energy change and standard enthalpy change disclosed that the mechanism of adsorption onto melamine was physisorption. The results will be useful for further applications of system design in the treatment of practical waste effluents.
Correlation between the uncoupling metabolism induced by 2,4,6-trichlorophenol and sludge toxicity in sequence batch reactors
Authors: Chen Xiurong , Lu Quanling , Wang Shanshan , Sun Xiaoli , Li Qiuyue , Wei Xiao , Yang Yingying , Wang Yuan
Published: October 2020

The correlation between sludge reduction induced by 2,4,6-trichlorophenol (2,4,6-TCP) as an uncoupler and sludge toxicity was investigated in sequence batch reactors over a 100-d operation period. The influent concentrations of 2,4,6-TCP tested were 10 mg/L, 30 mg/L, and 50 mg/L. Sludge reduction, chemical oxygen demand (COD) removal rate, and sludge toxicity were measured. The results showed that from 30 to 80 d, when the COD removal rate was at an acceptable level, the sludge reduction levels for the 10 mg/L, 30 mg/L, and 50 mg/L groups were 9.7%, 31.6%, and 41.5%, respectively, and the average sludge toxicity values were 24.2%, 38.0%, and 53.0%, respectively. Sludge reduction was positively correlated with sludge toxicity. The two-dimensional polyacrylamide gel electrophoresis/results showed that extracellular and intracellular proteins secreted by the activated sludge during uncoupling metabolism were positively correlated with sludge toxicity. Taking the COD removal rate, sludge reduction, and sludge toxicity into consideration, the optimal influent concentration of the uncoupler 2,4,6-TCP was 30 mg/L when the initial mixed liquid suspended solids of sludge was 2,500 mg/L.
Dissolved organic matter and bacterial population changes during the treatment of solid potato waste in a microbial fuel cell
Authors: Du Haixia , Wu Yanxia , Wu Huifang
Published: October 2020

This study investigated the effect of mixed feeding of anaerobically cultured waste activated sludge (WAS) on the performance of microbial fuel cells (MFCs) in the treatment of solid potato waste. The maximum current densities of the four MFCs was estimated as 36, 5, 10 and 150 mA/m2, with the columbic efficiencies of 6.1, 0.3, 0.9 and 31.1%, respectively. Composition changes of dissolved organic matter (DOM) coupled with its interrelation with electricity generation and total and viable bacterial population at the end of the operation were investigated. The experimental results demonstrated that mixing WAS into solid potato enhanced the presence of the tyrosine-like aromatic amino acids and aromatic protein-like substances from the beginning of the operation and promoted hydrolysis and humification of the solid potato. In the final solution of the anodic chamber, more viable bacteria were detected for the reactors treating solid potato alone and the mixed feedstock with the smaller amount of sludge, where distinct electricity generation was observed.
Применения базальтовой фибры в портландцементных системах
Authors: Levchuck Natalia , Shlyahova Ekatierina
Published: October 2020

При изучении литературных источников авторами статьи был выявлен ряд спорных вопросов, касающихся физико-химических процессов, протекающих в портландцементной системе с добавлением базальтовой фибры.В связи с этим была проведена серия экспериментов по изучению свойств базальтовой фибры, обработанной коллоидным гидроксидом алюминия, а также предложена технология введения ее в бетонную смесь и представлен анализ результатов эксперимента.
Synthesis of Kit-6 Magnetite Silica Nanocomposite Functionalized by Amine Group for Removal of Carmoisine Dye from Aqueous Solutions
Authors: Danesh Seyedeh Mahsa Seyed , Shariati Shahab , Faghihian Hossein
Published: October 2020

Objective:

In this study, amine functionalized magnetite Kit-6 silica nanocomposite (Fe3O4@SiO2@Kit-6-NH2) was synthesized as an adsorbent for removing Carmoisine food dye from aqueous solutions.

Method:

The nanocomposite was chemically synthesized and was characterized by X-ray diffraction analysis (XRD), vi-brating sample magnetometer (VSM), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). Taguchi orthogonal array experimental design method was used to op-timize the experimental conditions including adsorbent amount, pH of solution, amount of salt, the volume of sample and contact time. Pseudo first-order, pseudo second-order, intra-particle diffusion and Elovich kinetic models were investigated to study the kinetic parameters of sorption process.

Results:

The kinetic data corresponded to the pseudo second-order kinetic model with R2 = 0.9999. Also, adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherm models. The results indicated that the data were well fitted to the Freundlich isotherm model (R2 = 0.9984, n=1.0786). The reusability tests showed the proposed nanocomposite can be used more than 8 cycles with removal efficiency higher than 90%.

Conclusion:

The applicability study of proposed nanocomposite proved its ability for efficient removal of Carmoisine dye from real aqueous samples.
Energy Consumption in North America: Visualization and Pyramidal Perspective
Authors: Lagunas Puls Sergio , Oropeza Tagle Miguel Ángel , Boggio Vázquez Juan Bautista
Published: October 2020

El objetivo es visualizar y simular el consumo de energía en América del Norte, mediante pirámides de cuatro caras, en donde el polígono de la base está conformado por cuatro puntos del consumo no renovable, y la cúspide, representada por el ápice o punto superior, corresponde al consumo o alternativas renovables. Se inicia con los antecedentes del consumo de energía en el mundo, siguiendo con la revisión de la literatura acerca de propuestas relacionadas a la demanda de petróleo y derivados. Posteriormente se presenta la metodología y simulación encontrando en los resultados que, reduciendo consumo de productos de refinamiento medio y combustibles, se provocaría mayor altura en la cúspide de las pirámides, interpretada como el aumento de las energías renovables.