Waste Disposal & Sustainable Energy最新文献

{"title":"Improved slagging characteristics of low-value solid waste fuel asphalt rock by mineral additives of CaCO3, MgO, and Kaolin under fluidized bed condition","authors":"Jiatao Xiang,&nbsp;Xiong Zhang,&nbsp;Fan Yi,&nbsp;Shihong Zhang,&nbsp;Haiping Yang,&nbsp;Jing’ai Shao,&nbsp;Xianhua Wang,&nbsp;Hanping Chen","doi":"10.1007/s42768-023-00182-y","DOIUrl":"10.1007/s42768-023-00182-y","url":null,"abstract":"<div><p>As a low-value solid waste fuel, asphalt rock is prone to slagging even under fluidized bed condition. The purpose of this study is to improve the slagging characteristics of asphalt rock by adding the mineral additives CaCO₃, MgO, and Kaolin. The results showed that the K, Al, Ca salts in asphalt rock ash will evolve at different temperatures and exist mainly as K₂SO₄, KAlSiO₄, Al₂O₃·SiO₂, Al₂O₃, CaSO₄, and CaSiO₃. The CaSO₄ formed from sulfur oxides and calcium-containing compounds is the main factor in asphalt rock slagging and can be facilitated by CaSiO₃ with a small amount of CaCO₃. The MgO can form MgCa(SiO₃)₂ with a high melting point and helps raise the ash fusion temperatures. In addition, the Kaolin will promote the formation of low-temperature eutectics, resulting in a slight decrease in ash fusion temperatures. Through optimization, it was found that with the addition of 9.0% MgO+9.0% Kaolin+2.0% CaCO₃ (in weight), the slagging ratio and pressure difference of asphalt rock under fluidized bed conditions decreased from 6.5% to 4.2% and from 6.0 Pa to 4.0 Pa, respectively. By combining simulation and experimental methods, it has been shown that appropriate mineral additives of CaCO₃, MgO, and Kaolin can effectively improve the slagging characteristics of asphalt rock.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"385 - 400"},"PeriodicalIF":0.0,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140970517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facile and environmentally sustainable synthesis of bone waste derived biochar-based bimetallic-LDH nanocomposite for selected dyes removal from aqueous medium","authors":"Shanthi Prabha Viswanathan,&nbsp;Giya Merline Kuriakose,&nbsp;Gopika Vijayakumar Njazhakunnathu,&nbsp;Sreekanth Prakasan Neelamury,&nbsp;Thomas Paili Ambatt","doi":"10.1007/s42768-024-00195-1","DOIUrl":"10.1007/s42768-024-00195-1","url":null,"abstract":"<div><p>The disposal of bone waste can be effectively addressed utilizing a novel approach involving the synthesis of a bovine bone-derived biochar-based Mg/Al-layered double hydroxide (LDH) nanocomposite (B-Mg/Al-NC). This nanocomposite exhibits exceptional capabilities for removing specific dyes, such as Methylene Blue (MB) and Congo Red (CR), from aqueous media. Extensive characterization using techniques confirmed the successful formation of the B-Mg/Al-NC, which possesses a high surface area, high porosity, and abundant functional groups. The Langmuir monolayer biosorption capacity was 395.56 mg g⁻¹ and 328.25 mg g⁻¹ at 50 °C for MB and CR, respectively, with rapid dye removal achieved within 25 min under alkaline pH conditions. The experimental data fit well with the pseudo-second-order kinetics model for both dyes. The remarkable dye adsorption capacity of the B-Mg/Al-NC can be attributed to the combined basic properties of the bone biochar and Mg/Al-LDH. Proposed mechanisms for enhanced dye removal include hydrogen bonding interactions, anion exchange, surface complexation, electrostatic interactions, and pore filling. Furthermore, the nanocomposite exhibited excellent reusability. In addition to its dye removal capabilities, the B-Mg/Al-NC was found to have a positive effect on seed germination and growth and salient soil health parameters, as demonstrated by a rapid seed germination test using the spent composite. Overall, the facile synthesis of the B-Mg/Al-NC via co-precipitation and ultrasonication is a highly recommended and sustainable approach for producing an eco-friendly bio-sorbent with exceptional dye removal efficiency from wastewater while also addressing the issue of bone waste disposal.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"355 - 369"},"PeriodicalIF":0.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical study on the Cs/Cs-O adsorbed graphene/semiconductor heterojunction anode for thermionic converters","authors":"Weiting Sun,&nbsp;Haoran Xu,&nbsp;Hao Qiu,&nbsp;Gang Xiao","doi":"10.1007/s42768-024-00191-5","DOIUrl":"10.1007/s42768-024-00191-5","url":null,"abstract":"<div><p>Graphene/semiconductor heterojunction anodes can significantly enhance the output voltage by the photovoltaic effect. However, a significant challenge arises from the high intrinsic work function of heterojunction surfaces, which limits efficient electron emission. In this study, we explored the potential of low work function materials modified by Cs/Cs-O adsorption as anodes for thermionic (TI) converters through first principles calculations. The results demonstrate that the work functions of the graphene/MoS₂ and the graphene/n-type Si surfaces with only Cs coating can decrease to 1.48 eV and 2.46 eV, respectively. The multiple Cs-O atoms co-adsorption enhances the dipole moment, resulting in a further reduction of the work function of the graphene/MoS₂ surface to 1.25 eV. In addition, the impact of work function on the performance of TI converters is revealed by using concentrated solar energy as heat source. The highest conversion efficiency achieves 15.25% for the Cs-4O: Gr/MoS₂ anode. This study establishes a robust foundation for further advancement of the TI converters with graphene/semiconductor heterojunction anodes.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"439 - 450"},"PeriodicalIF":0.0,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140837411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research trends and prospects for hydrogen production from sludge fermentation: based on bibliometric analysis","authors":"Yunchuan Pan,&nbsp;Jiao Tao,&nbsp;Shijie Yang,&nbsp;Jianguo Cui,&nbsp;Jian Xiong,&nbsp;Xuebin Lu","doi":"10.1007/s42768-024-00190-6","DOIUrl":"10.1007/s42768-024-00190-6","url":null,"abstract":"<div><p>There are many applications for the technology of producing hydrogen from organic waste. Due to its large volume, high organic content, and stable source, sewage sludge has gained significant attention among various organic wastes. The purpose of this paper is to present a bibliometric and technological study of hydrogen production from anaerobic fermentation of sewage sludge during the last decade using data from the Web of Science. The analysis of authors, countries/regions, and keywords is the primary focus of the bibliometric study. In terms of technological advances, this paper reviews the mechanisms and influencing factors of hydrogen production from sewage sludge, and provides an overview of the research on pretreatment and co-fermentation that has been carried out in recent years to improve the hydrogen production rate. This paper discusses the challenges faced in anaerobic hydrogen production from sludge and concludes that more research is needed for its commercialization and large-scale application. This review provides references and ideas for sludge synergies in the utilization of organic solid waste resources.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"451 - 471"},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regression based prediction of higher heating value for refuse-derived fuel using convolutional neural networks predicted elemental data and spectrographic measurements","authors":"Baki Osman Bekgöz,&nbsp;Zerrin Günkaya,&nbsp;Kemal Özkan,&nbsp;Metin Özkan,&nbsp;Aysun Özkan,&nbsp;Müfide Banar","doi":"10.1007/s42768-023-00187-7","DOIUrl":"10.1007/s42768-023-00187-7","url":null,"abstract":"<div><p>Higher heating value (HHV) is the key parameter for replacing Refuse-Derived Fuel (RDF) with fossil fuels in the cement industry. HHV can be measured with a bomb calorimeter or predicted from direct elemental data by using regression models. Both methods require the continuous use of special laboratory equipment and are time consuming. To overcome these limitations, this study aims to predict the HHV value of RDF from predicted elemental data by using regression models. Therefore, once the predicted elemental data are generated, there will be no need to have continuous elemental data to predict HHV. Predicted elemental data were generated from direct elemental data and Near Infrared (NIR) camera-based spectrometric data by using a deep learning model. A convolutional neural networks (CNN) model was used for deep learning and was trained with 10,500 NIR image samples, each of which was 28×28×1. Different regression models (Linear, Tree, Support-Vector Machine, Ensemble and Gaussian process) were applied for HHV prediction. According to these results, higher <i>R</i>² values (&gt;0.85) were obtained with Gaussian process models (except for the Rational Quadratic model) for the predicted elemental data. Among the Gaussian models, the highest <i>R</i>² (0.95) but the lowest Root Mean Square Error (RMSE) (0.0563), Mean Squared Error (MSE) (0.0317) and Mean Absolute Error (MAE) (0.0431) were obtained with the Mattern 5/2 model. The results of predictions from predicted elemental data were compared to predictions from direct elemental data. The results show that the regression from predicted elemental data has an adequate prediction (<i>R</i>²=0.95) compared to the prediction from the direct elemental data (<i>R</i>²=0.99).</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"429 - 437"},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s42768-023-00187-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140675510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparation of crab-shell-based N, O co-doped graded porous carbon for supercapacitors using the confined nanospace deposition method","authors":"Yiming Li,&nbsp;Zhihao Yu,&nbsp;Mengyan Guo,&nbsp;Ming Zhang,&nbsp;Jian Xiong,&nbsp;Yina Qiao,&nbsp;Rui Zhang,&nbsp;Xuebin Lu","doi":"10.1007/s42768-024-00199-x","DOIUrl":"10.1007/s42768-024-00199-x","url":null,"abstract":"<div><p>Biomass-based carbon materials with hierarchical porous structures have attracted attention for their ability to provide more channels and shorten ion transport paths. Here, we developed a simple method based on confined nanospace deposition. During high-temperature treatment, the mesoporous silica layer wrapped around the outside of the crab shells acted as a closed nanospace and effectively suppressed the severe deformation of the crab shell structure by shrinking inward. The prepared carbon material has a layered porous structure with abundant and stable N and O co-doping (N 7.32%, O 3.69%). The specific capacitance of the three-electrode system was 134.3 F/g at a current density of 0.5 A/g in a 6 mol/L KOH electrolyte, and the assembled aqueous symmetric supercapacitors exhibited an excellent cycling stability of 98.81% even after 5000 cycles.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 2","pages":"173 - 183"},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global household infectious waste management strategies: a systematic review","authors":"Leila Mohammadinia,&nbsp;Khadijeh Raei,&nbsp;Fathollah Gholami-Borujeni","doi":"10.1007/s42768-024-00192-4","DOIUrl":"10.1007/s42768-024-00192-4","url":null,"abstract":"<div><p>Infectious waste management is a major environmental and public health challenge worldwide. Household infectious wastes are often mixed with other waste, collected, and disposed of without taking measures to reduce risks. With the emergence of the COVID-19 virus in early December 2019, there have been concerns about the dangers of infectious waste generated in healthcare facilities and homes. Therefore, this review was conducted with the aim of investigating the methods of household infectious waste management in different countries/regions and evaluating the factors affecting the management of household infectious waste. In this study, we conducted a systematic literature search in four electronic databases (PubMed, Web of Science, Scopus, and ProQuest) to answer the research questions. This process was based on the new version of PRISMA guidelines. In total, 52 documents out of 6742 were selected and evaluated. The review of studies based on content analysis led to the emergence of 12 main themes, 36 sub-themes, and 112 codes. The main topics included education and culture, management measures, legal social support, economic support, technology, control and evaluation, waste generation, classification and collection, temporary storage, transportation, processing and recycling, and safe disposal. The factors affecting household infectious waste management identified in this research can serve as a basis for future studies. It is also suitable for providing a comprehensive guide to the management of household infectious waste.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"371 - 384"},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent trends on energy-efficient solar dryers for food and agricultural products drying: a review","authors":"Kavati Venkateswarlu,&nbsp;S. V. Kota Reddy","doi":"10.1007/s42768-024-00193-3","DOIUrl":"10.1007/s42768-024-00193-3","url":null,"abstract":"<div><p>The energy efficiency enhancement of solar dryers has attracted the attention of researchers worldwide because of the need for energy storage in solar drying applications, which arises primarily from the irregular nature of solar energy that leads to improper drying which will reduce the quality of the products being dried. This work comprehensively reviews the state-of-the-art research carried out on solar dryers for energy efficiency enhancement using various alternative strategies, including hybrid solar dryers that use auxiliary heating sources, such as electric heaters or biomass heaters, solar-assisted heat pump dryer, use of desiccant materials, and heat storage systems that use both sensible and latent heat storage. The advent of phase change materials (PCM), such as thermally and chemically stable PCMs, for long-term storage, bio-degradable and bio-compatible PCM materials to alleviate the negative environmental impact of conventional PCMs is also presented. The performance parameters considered for evaluating dryers include the maximum temperature attained inside the drying chamber, drying time and efficiency, specific moisture extraction rate (SMER), energy and exergy efficiency and CO₂ mitigation effect. The factors considered to analyze the PCMs application in solar dryers include cost and sustainability of PCMs, and both energy and exergy analyses of dryers using PCMs. The gaps in current knowledge and future scope for further improvement of solar dryers are also elucidated.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"335 - 353"},"PeriodicalIF":0.0,"publicationDate":"2024-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s42768-024-00193-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sustainable bio-energy generation via the conversion of spent wash using dual chamber microbial fuel cell","authors":"Abdul Sattar Jatoi,&nbsp;Jawad Ahmed,&nbsp;Afaque Ahmed Bhutto,&nbsp;Muhammad Shuaib Shaikh","doi":"10.1007/s42768-024-00189-z","DOIUrl":"10.1007/s42768-024-00189-z","url":null,"abstract":"<div><p>Microbial fuel cells (MFCs) are innovative devices that combine microbial processes with electrochemical reactions to convert organic matter in wastewater into electricity while simultaneously treating the wastewater. One such application is the treatment of spent wash, a highly polluting effluent generated from the distillery industry after crude mesh is separated into ethanol and spent wash. Spent wash, also known as distillery effluent or stillage, is a highly challenging wastewater treatment method due to its high chemical oxygen demand (COD), biological oxygen demand (BOD), and total dissolved solids (TDS). These characteristics make it a complex and polluting industrial effluent that requires specialized treatment processes to reduce its environmental impact effectively. However, MFCs have shown promise in treating spent wash, as they can utilize the organic matter in wastewater as a fuel source for microbial growth as well as for electricity generation. For the treatment of spent wash, <i>Saccharomyces cerevisiae</i> sp. was used as a biocatalyst along with 340 mol/L potassium ferricyanide in the cathode chamber and 170 mol/L methylene blue in the anode as a mediator. All tests were conducted by balancing a one-liter volume for power production from spent wash in MFC with the optimal conditions of 10% agarose, pH 8.5, 300 mL/min of aeration in the cathode chamber, and 40% (in weight) substrate concentration. At an ideal concentration, the maximum current and power density are roughly 53.41 mA/m² and 72.22 mW/m², respectively. For each litre of processed spent wash, a maximum voltage of 850 mV (4.5 mA) was obtained. Amazingly, 91% of COD and BOD were removed from the effluent MFC. These findings show that MFCs are capable of producing electricity and efficiently removing COD from wasted wash at the same time.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 2","pages":"219 - 231"},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Co-production of biochar and carbon nanotube from sewage sludge in a two-stage process coupling pyrolysis and catalytic chemical vapor deposition","authors":"Mohd Syazwan Mohd Ghazali,&nbsp;Mohd Saufi Md Zaini,&nbsp;Muhammad Arshad,&nbsp;Syed Shatir A. Syed-Hassan","doi":"10.1007/s42768-024-00194-2","DOIUrl":"10.1007/s42768-024-00194-2","url":null,"abstract":"<div><p>This study explores the potential of valorizing sewage sludge as a carbon source for the co-production of biochar and carbon nanomaterial via a two-stage thermal-catalytic process. In the first stage, sewage sludge underwent slow pyrolysis, resulting in a biochar yield of 66% (in weight) at 550 °C. The resulting pyrolysis vapor was then introduced into a second reactor, where catalytic chemical vapor deposition (CCVD) took place in the presence of a cobalt catalyst, leading to the production of carbon nanotubes (CNTs). It was found that CNTs with an inner diameter of ~ 3.2 nm and an outer diameter of 20–40 nm can be formed in the second stage reactor at temperatures between 650 °C and 950 °C with a maximum yield of 30% (in weight) under the employed experimental conditions. The obtained CNTs displayed a multiwall structure, exhibited a lack of crystallinity, and demonstrated a high level of disorder. The research findings also indicate that temperature exerts a significant influence on both the yield and properties of the CNTs synthesized.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"6 3","pages":"323 - 334"},"PeriodicalIF":0.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140298299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}