Skip to main content

Polymers For 3d Printing

Download Polymers For 3d Printing Full eBooks in PDF, EPUB, and kindle. Polymers For 3d Printing is one my favorite book and give us some inspiration, very enjoy to read. you could read this book anywhere anytime directly from your device.

Polymers for 3D Printing

Polymers for 3D Printing Book
Author : Joanna Izdebska-Podsiadły
Publisher : William Andrew
Release : 2022-06-05
ISBN : 0128183128
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Polymers for 3D Printing: Methods, Properties, and Characteristics provides a detailed guide to polymers for 3D printing, bridging the gap between research and practice, and enabling engineers, technicians and designers to utilise and implement this technology for their products or applications. Presents the properties, attributes, and potential applications of the polymeric materials used in 3D printing Analyses and compares the available methods for 3D printing, with an emphasis on the latest cutting-edge technologies Enables the reader to select and implement the correct 3D printing technology, according to polymer properties or product requirements

3D Industrial Printing with Polymers

3D Industrial Printing with Polymers Book
Author : Johannes Karl Fink
Publisher : John Wiley & Sons
Release : 2018-11-30
ISBN : 1119555310
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

3D industrial printing has become mainstream in manufacturing. This unique book is the first to focus on polymers as the printing material. The scientific literature with respect to 3D printing is collated in this monograph. The book opens with a chapter on foundational issues such and presents a broad overview of 3D printing procedures and the materials used therein. In particular, the methods of 3d printing are discussed and the polymers and composites used for 3d printing are detailed. The book details the main fields of applications areas which include electric and magnetic uses, medical applications, and pharmaceutical applications. Electric and magnetic uses include electronic materials, actuators, piezoelectric materials, antennas, batteries and fuel cells. Medical applications are organ manufacturing, bone repair materials, drug-eluting coronary stents, and dental applications. The pharmaceutical applications are composite tablets, transdermal drug delivery, and patient-specific liquid capsules. A special chapter deals with the growing aircraft and automotive uses for 3D printing, such as with manufacturing of aircraft parts and aircraft cabins. In the field of cars, 3D printing is gaining importance for automotive parts (brake components, drives), for the fabrication of automotive repair systems, and even 3D printed vehicles.

3D and 4D Printing of Polymer Nanocomposite Materials

3D and 4D Printing of Polymer Nanocomposite Materials Book
Author : Kishor Kumar Sadasivuni,Kalim Deshmukh,Mariam Ali S A Al-Maadeed
Publisher : Elsevier
Release : 2019-10-11
ISBN : 0128173025
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

3D and 4D Printing of Polymer Nanocomposite Materials: Processing, Applications, and Challenges covers advanced 3D and 4D printing processes and the latest developments in novel polymer-based printing materials, thus enabling the reader to understand and benefit from the advantages of this groundbreaking technology. The book presents processes, materials selection, and printability issues, along with sections on the preparation of polymer composite materials for 3D and 4D printing. Across the book, advanced printing techniques are covered and discussed thoroughly, including fused deposition modeling (FDM), selective laser sintering (SLS), selective laser melting (SLM), electron beam melting (EBM), inkjet 3D printing (3DP), stereolithography (SLA), and 3D plotting. Finally, major applications areas are discussed, including electronic, aerospace, construction and biomedical applications, with detailed information on the design, fabrication and processing methods required in each case. Provides a thorough, clear understanding of polymer preparation techniques and 3D and 4D printing processes, with a view to specific applications Examines synthesis, formation methodology, the dispersion of fillers, characterization, properties, and performance of polymer nanocomposites Explores the possibilities of 4D printing, covering the usage of stimuli responsive hydrogels and shape memory polymers

Functional Materials

Functional Materials Book
Author : Dipti Ranjan Sahu
Publisher : BoD – Books on Demand
Release : 2019-10-09
ISBN : 1789840570
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Functional materials are important materials for any technological needs and the forefront of materials research. Development of functional materials and their effective applications in the frontier fields of cross-multidisciplinary research programs is unique. This book presents an overview of different types of functional materials, including synthesis, characterization and application, and up-to-date treatment of functional materials, which are needed for structural, magnetic, polymeric, electromagnetic, etc. applications. New topics based on polymeric materials and spintronic materials are given for possible applications. The chapters of the book provide a key understanding of functional materials. It is suitable for undergraduates, graduates, and professionals, including engineers, scientists, researchers, technicians, and technology managers.

Self Assembly Lab

Self Assembly Lab Book
Author : Skylar Tibbits
Publisher : Taylor & Francis
Release : 2016-11-10
ISBN : 1317437020
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

What if structures could build themselves or adapt to fluctuating environments? Skylar Tibbits, Director of the Self-Assembly Lab in the Department of Architecture at MIT, Cambridge, MA, crosses the boundaries between architecture, biology, materials science and the arts, to envision a world where material components can self-assemble to provide adapting structures and optimized fabrication solutions. The book examines the three main ingredients for self-assembly, includes interviews with practitioners involved in the work and presents research projects related to these topics to provide a complete first look at exciting future technologies in construction and self-transforming material products.

3D Printing with Biomaterials

3D Printing with Biomaterials Book
Author : A.J.M. van Wijk,I. van Wijk
Publisher : IOS Press
Release : 2015-01-15
ISBN : 1614994862
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Additive manufacturing or 3D printing, manufacturing a product layer by layer, offers large design freedom and faster product development cycles, as well as low startup cost of production, on-demand production and local production. In principle, any product could be made by additive manufacturing. Even food and living organic cells can be printed. We can create, design and manufacture what we want at the location we want. 3D printing will create a revolution in manufacturing, a real paradigm change. 3D printing holds the promise to manufacture with less waste and energy. We can print metals, ceramics, sand, synthetic materials such as plastics, food or living cells. However, the production of plastics is nowadays based on fossil fuels. And that’s where we witness a paradigm change too. The production of these synthetic materials can be based also on biomaterials with biomass as feedstock. A wealth of new and innovative products are emerging when we combine these two paradigm changes: 3D printing and biomaterials. Moreover, the combination of 3D printing with biomaterials holds the promise to realize a truly sustainable and circular economy.

Carbon Nanotubes and Graphene

Carbon Nanotubes and Graphene Book
Author : Kazuyoshi Tanaka,S. Iijima
Publisher : Newnes
Release : 2014-07-10
ISBN : 0080982689
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Carbon Nanotubes and Graphene is a timely second edition of the original Science and Technology of Carbon Nanotubes. Updated to include expanded coverage of the preparation, purification, structural characterization, and common application areas of single- and multi-walled CNT structures, this work compares, contrasts, and, where appropriate, unitizes CNT to graphene. This much expanded second edition reference supports knowledge discovery, production of impactful carbon research, encourages transition between research fields, and aids the formation of emergent applications. New chapters encompass recent developments in the theoretical treatments of electronic and vibrational structures, and magnetic, optical, and electrical solid-state properties, providing a vital base to research. Current and potential applications of both materials, including the prospect for large-scale synthesis of graphene, biological structures, and flexible electronics, are also critically discussed. Updated discussion of properties, structure, and morphology of biological and flexible electronic applications aids fundamental knowledge discovery Innovative parallel focus on nanotubes and graphene enables you to learn from the successes and failures of, respectively, mature and emergent partner research disciplines High-quality figures and tables on physical and mathematical applications expertly summarize key information – essential if you need quick, critically relevant data

3D Printing in Medicine

3D Printing in Medicine Book
Author : Deepak M Kalaskar
Publisher : Woodhead Publishing
Release : 2017-04-17
ISBN : 0081007264
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

3D Printing in Medicine examines the emerging market of 3D-printed biomaterials and its clinical applications. With a particular focus on both commercial and premarket tools, the book looks at their applications within medicine and the future outlook for the field. The book begins with a discussion of the fundamentals of 3D printing, including topics such as materials, and hardware. Chapters go on to cover applications within medicine such as computational analysis of 3D printed constructs, personalized 3D printing and 3D cell and organ printing. The concluding chapters in the book review the applications of 3D printing in diagnostics, drug development, 3D-printed disease models and 3D printers for surgical practice. With a strong focus on the translation of 3D printing technology to a clinical setting, this book is a valuable resource for scientists and engineers working in biomaterial, biomedical, and nanotechnology based industries and academia. Provides a comprehensive and authoritative overview of all the medical applications of 3D printing biomaterials and technologies Focuses on the emerging market of 3D printed biomaterials in clinical applications Reviews both commercial and under development materials, tools, their applications, and future evolution

Fused Deposition Modeling Based 3D Printing

Fused Deposition Modeling Based 3D Printing Book
Author : Harshit K. Dave,J. Paulo Davim
Publisher : Springer Nature
Release : 2021-04-21
ISBN : 303068024X
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

This book covers 3D printing activities by fused deposition modeling process. The two introductory chapters discuss the principle, types of machines and raw materials, process parameters, defects, design variations and simulation methods. Six chapters are devoted to experimental work related to process improvement, mechanical testing and characterization of the process, followed by three chapters on post-processing of 3D printed components and two chapters addressing sustainability concerns. Seven chapters discuss various applications including composites, external medical devices, drug delivery system, orthotic inserts, watertight components and 4D printing using FDM process. Finally, six chapters are dedicated to the study on modeling and optimization of FDM process using computational models, evolutionary algorithms, machine learning, metaheuristic approaches and optimization of layout and tool path.

3D Printing for Tissue Engineering and Regenerative Medicine

3D Printing for Tissue Engineering and Regenerative Medicine Book
Author : Murat Guvendiren ,Vahid Serpooshan
Publisher : MDPI
Release : 2020-12-02
ISBN : 3039361120
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Three-dimensional (3D) printing enables the fabrication of tissue-engineered constructs and devices from a patient’s own medical data, leading to the creation of anatomically matched and patient-specific constructs. There is a growing interest in applying 3D printing technologies in the fields of tissue engineering and regenerative medicine. The main printing methods include extrusion-based, vat photopolymerization, droplet-based, and powder-based printing. A variety of materials have been used for printing, from metal alloys and ceramics to polymers and elastomers as well as from hydrogels to extracellular matrix proteins. More recently, bioprinting, a subcategory of 3D printing, has enabled the precise assembly of cell-laden biomaterials (i.e., bioinks) for the construction of complex 3D functional living tissues or artificial organs. In this Special Issue, we aim to capture state-of-the-art research papers and the most current review papers focusing on 3D printing for tissue engineering and regenerative medicine. In particular, we seek novel studies on the development of 3D printing and bioprinting approaches, developing printable materials (inks and bioinks), and utilizing 3D-printed scaffolds for tissue engineering and regenerative medicine applications. These applications are not limited to but include scaffolds for in vivo tissue regeneration and tissue analogues for in vitro disease modeling and/or drug screening.

Functionalized Polymers

Functionalized Polymers Book
Author : Narendra Pal Singh Chauhan
Publisher : CRC Press
Release : 2021-05-14
ISBN : 1000291170
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Functionalized polymers are macromolecules to which chemically bound functional groups are attached which can be used as catalysts, reagents, protective groups, etc. Functionalized polymers have low cost, ease of processing and attractive features for functional organic molecules. Chemical reactions for the introduction of functional groups in polymers and the conversion of functional groups in polymers depend on different properties. Such properties are of great importance for functionalization reactions for possible applications of reactive polymers. This book deals with the synthesis and design of various functional polymers, the modification of preformed polymer backbones and their various applications.

Polymer Based Additive Manufacturing

Polymer Based Additive Manufacturing Book
Author : Declan M. Devine
Publisher : Springer Nature
Release : 2019-09-16
ISBN : 3030245322
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

This book aims to give readers a basic understanding of commonly used additive manufacturing techniques as well as the tools to fully utilise the strengths of additive manufacturing through the modelling and design phase all the way through to post processing. Guidelines for 3D-printed biomedical implants are also provided. Current biomedical applications of 3D printing are discussed, including indirect applications in the rapid manufacture of prototype tooling and direct applications in the orthopaedics, cardiovascular, drug delivery, ear-nose-throat, and tissue engineering fields. Polymer-Based Additive Manufacturing: Biomedical Applications is an ideal resource for students, researchers, and those working in industry seeking to better understand the medical applications of additive manufacturing.

Additive Manufacturing 3D Printing Design

Additive Manufacturing  3D Printing   Design Book
Author : Dr. Sabrie Soloman
Publisher : Dr. Sabrie Soloman
Release : 2023-01-27
ISBN : 0987650XXX
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Additive Manufacturing 3D Printing & Design The 4th Revolution Not ever previously consumer has had a technology where we so easily interpret the concepts into a touchable object with little concern to the machinery or talents available. If “seeing is believing!-” 3D printing technology is the perfect object image to see, touch, and feel! It is the wings to lift the well sought product, after laboring and toiling in several design iterations to bring the novel product to be a successful implementation. Now it is promising to become familiar with the product prototype and physically test it to find the flaws in the design. If a flaw is detected, the designer can easily modify the CAD file and print out a new unit. On Demand Custom Part Additive manufacturing has become a mainstream manufacturing process. It builds up parts by adding materials one layer at a time based on a computerized 3D solid model. It does not require the use of fixtures, cutting tools, coolants, and other auxiliary resources. It allows design optimization and the producing of customized parts on-demand. Its advantages over conventional manufacturing have captivated the imagination of the public, reflected in recent corporate implementations and in many academic publications that call additive manufacturing the “fourth industrial revolution.” Digital Model Layer by Layer 3D additive manufacturing is a process tailored for making three-dimensional objects of varieties of different shapes created from digital models. The objects are produced using an additive process, where successive layers of materials are deposited down in different shapes. The 3D Additive Manufacturing is considered diverse from traditional machining techniques, which depends primarily on the removal of material by cutting or drilling. The removal of material is referred to as a “subtractive process.” In a fast-paced, pressure-filled business atmosphere, it is clear that decreasing delivery by days is exceptionally valuable. Digital Manufacturing 3D printing - additive manufacturing, produces 3D solid items from a digital computer file. The printing occurs in an additive process, where a solid object is generated through the consecutive layering of material. There are an extensive variety of materials to select from countless lists of polymers and metals. The process begins with the generation of a 3D digital file such as CAD file. The 3D digital file is then directed to a 3D printer for printing using a simple print command. Freed of the constraints of traditional factories, additive manufacturing allows designers to produce parts that were previously considered far too complex to make economically. Engineers and Biologists are finding practical applications to use 3D additive manufacturing. It permits novel designs to become matchless rare-products that were not likely with preceding manufacturing methods. It is poised to transform medicine and biology with bio-manufacturing. This technology has the possibility to upsurge the well-being of a nation’s citizens. Additive manufacturing may progress the worldwide resources and energy effectiveness in ground, sea and air. This 3D Printing & Design book will enable you to develop and 3D print your own unique object using myriads of worldwide materials. Galilee Galileo & Isaac Newton Galileo Galilei and Isaac Newton have changed our understanding of not only our own solar system, but also the whole universe through the invention of their telescope. The telescope steered a novel and captivating scientific discipline of “astronomy” —observing and studying the planets, stars, and other objects in the universe. The Nebula, for example, could not be observed prior to the invention of the telescope. No one could have estimated how many planets were in our solar system. Thanks to the technology of the telescope, the knowledge of universe was revealed. Thanks to a simple piece of glass made of silica, and to a simple lens made of glass. Similarly, 3D printing technology is a simple approach to open a flood gate to our Fourth Industrial Revolution. One-off Prototype One-off prototypes can be hideously expensive to produce, but a 3D printer can bring down the cost by a sizable margin. Many consumers goods, mechanical parts, aerospace, automobiles, robots, shoes, fashions, architects' models, dentures, hearing aids, cell biology, now appear in a 3D-printed form for appraisal by engineers, stylists, biologist, and clients before obtaining the final approval. Any changes can be swiftly reprinted in a few hours or overnight, whereas waiting for a new prototype to emerge from a machine shop could take weeks, and sometimes months. Some designers are already printing ready-to-wear shoes, dresses, and prosthetics, from metals, plastic and nylon materials. 3D printing’s utmost advantage is making discrete parts rapidly, autonomous of design complications. That speed delivers rapid reaction on the first prototype, and the capability to modify the design and speedily re-manufacture the part. As an alternative of waiting days or weeks for a CNC-machined prototype, a 3D printer can manufacture the part overnight. Development Cycle The 3D printer provides the additional advantage of removing many overhead manufacturing costs and time-delay by 3D printing parts that withstand a machine shop environment. Several tooling, fixtures, and work-holding jaws may be easily developed and 3D printed without extensive lead time and overhead cost. Its speed and quality shorten the product development cycle, permitting manufacturing aesthetically appealing, and high-performance parts in less than a day. Many instances testify that 3D printers offer substantial flexibility to yield parts with the adequate tensile strength and quality, desired to prosper the technology at a reasonable speed and cost. The rewards of applying 3D printing are substantial, as 3D printing permits product development teams to effortlessly, rapidly, and cost effectively yield models, prototypes, and patterns. Parts can be manufactured in hours or days rather than weeks. Nano-bots 3D additive manufacturing may be the only known method for constructing nanobots, which will overcome the speed disadvantage of 3D additive printing, thereby enabling the technology to be widely deployed in every manufacturing aspect. If millions of nanobots worked together, they might be able to do amazing manufacturing takes. Microscopic Surgery Scientists and researchers constructed teams of nanobots able to perform microscopic surgery inside a patient’s body. Some groups of

3D Printing of Pharmaceuticals and Drug Delivery Devices

3D Printing of Pharmaceuticals and Drug Delivery Devices Book
Author : Dimitrios A. Lamprou
Publisher : MDPI
Release : 2020-07-01
ISBN : 3039364235
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

The 3D printing (3DP) process was patented in 1986; however, only in the last decade has it begun to be used for medical applications, as well as in the fields of prosthetics, bio-fabrication, and pharmaceutical printing. 3DP or additive manufacturing (AM) is a family of technologies that implement layer-by-layer processes in order to fabricate physical models based on a computer aided design (CAD) model. 3D printing permits the fabrication of high degrees of complexity with great reproducibility in a fast and cost-effective fashion. 3DP technology offers a new paradigm for the direct manufacture of individual dosage forms and has the potential to allow for variations in size and geometry as well as control dose and release behavior. Furthermore, the low cost and ease of use of 3DP systems means that the possibility of manufacturing medicines and medical devices at the point of dispensing or at the point of use could become a reality. 3DP thus offers the perfect innovative manufacturing route to address the critical capability gap that hinders the widespread exploitation of personalized medicines for molecules that are currently not easy to deliver. This Special Issue will address new developments in the area of 3D printing and bioprinting for drug delivery applications, covering the recent advantages and future directions of additive manufacturing for pharmaceutical products.

Reactive Oligomers

Reactive Oligomers Book
Author : Frank Wayne Harris
Publisher : Amer Chemical Society
Release : 1985
ISBN : 0987650XXX
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

Serves as the first book to look at the many applications of various types of oligomers. Describes oligomer synthesis and subsequent reactions by cationic, anionic, free radical, and condensation techniques. Reports on different applications with similar research approaches, including composite resins, electronic coatings, high solids paints, and more.

Additive Manufacturing Technologies

Additive Manufacturing Technologies Book
Author : Ian Gibson,David Rosen,Brent Stucker
Publisher : Springer
Release : 2014-11-26
ISBN : 1493921134
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

This book covers in detail the various aspects of joining materials to form parts. A conceptual overview of rapid prototyping and layered manufacturing is given, beginning with the fundamentals so that readers can get up to speed quickly. Unusual and emerging applications such as micro-scale manufacturing, medical applications, aerospace, and rapid manufacturing are also discussed. This book provides a comprehensive overview of rapid prototyping technologies as well as support technologies such as software systems, vacuum casting, investment casting, plating, infiltration and other systems. This book also: Reflects recent developments and trends and adheres to the ASTM, SI, and other standards Includes chapters on automotive technology, aerospace technology and low-cost AM technologies Provides a broad range of technical questions to ensure comprehensive understanding of the concepts covered

Natural Polymers

Natural Polymers Book
Author : Jissy Jacob,Fernando Gomes,Józef T. Haponiuk,Nandakumar Kalarikkal,Sabu Thomas
Publisher : CRC Press
Release : 2022-03-24
ISBN : 1000292150
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

This new volume, Natural Polymers: Perspectives and Applications for a Green Approach, covers the synthesis, characterizations, and properties of natural polymeric systems, including their morphology, structure, and dynamics. It also introduces the most recent innovations and applications of natural polymers and their composites in the food, construction, electronics, biomedical, pharmaceutical, and engineering industries. Natural polymers provide a striking substitute for various applications as compared to synthetic polymers obtained from petrochemicals because they are biocompatible, biodegradable, easily available, and fall within the budget of many industries. The applications of natural polymers in pharmaceutical industries are large in comparison to synthetic polymers and are also wide in scope in the food and cosmetic industries. This new volume provides the information needed to design new applications for natural polymers. This book is a valuable reference for researchers, academicians, chemists, pharmacists, researchers, scientists, industrialists dealing with applications of natural polymers and people working in field of natural polymers.

3D Printing with Light

3D Printing with Light Book
Author : Pu Xiao,Jing Zhang
Publisher : Walter de Gruyter GmbH & Co KG
Release : 2021-04-06
ISBN : 3110569841
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

The book introduces fundamentals of 3D printing with light, photoinitiating system for 3D printing as well as resins. Plenty of applications, trends and prospects are also discussed, which make the book an essential reference for both scientists and industrial engineers in the research fields of photochemistry, polymer chemistry, rapid prototyping and photopolymerization.

Functional Dyes

Functional Dyes Book
Author : Sung-Hoon Kim
Publisher : Elsevier
Release : 2006-03-08
ISBN : 0080465625
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

In the last 10 years organic dyes, traditionally used for coloring textiles and other materials, have become increasingly important in the hi-tech industries of electronics and optoelectronics. They can be used in optical data storage, new solar cells and biomedical sensors. Functional Dyes discusses the synthesis of these new, high-value dyes and pigments as well as their applications and performance. The chapters are arranged so that the reader logically advances from the fundamental concepts to more practical aspects of the technology in which they are used. In providing the reader with current information on functional dye chemistry, as well as important developments within the field, Functional Dyes is a valuable information source for dye and material chemists, researchers and graduates, who want a summary of the key advances in the field over the last 10 years and an authoritative view on future developments. * Provides a broad introduction to the science technology of the functional dye application * Reviews recent advances on synthesis and characteristics of the functional dyes and their applications * Is a valuable information source for dye and material chemists and researchers

Handbook of Sustainable Polymers for Additive Manufacturing

Handbook of Sustainable Polymers for Additive Manufacturing Book
Author : Antonio Paesano
Publisher : CRC Press
Release : 2022-05-12
ISBN : 1000470482
Language : En, Es, Fr & De

DOWNLOAD

Book Description :

This book provides the latest technical information on sustainable materials that are feedstocks for additive manufacturing (AM). Topics covered include an up-to-date and extensive overview of raw materials, their chemistry, and functional properties of their commercial versions; a description of the relevant AM processes, products, applications, advantages, and limitations; prices and market data; and a forecast of sustainable materials used in AM, their properties, and applications in the near future. Data included are relative to current commercial products and are presented in easy-to-read tables and charts. Features Highlights up-to-date information and data of actual commercial materials Offers a broad survey of state-of the-art information Forecasts future materials, applications, and areas of R&D Contains simple language, explains technical terms, and minimizes technical lingo Includes over 200 tables, nearly 200 figures, and more than 1,700 references to technical publications, mostly very recent Handbook of Sustainable Polymers for Additive Manufacturing appeals to a diverse audience of students and academic, technical, and business professionals in the fields of materials science and mechanical, chemical, and manufacturing engineering.