NewSenior iOS Application Engineer - 26-10216 Compu-Vision - ITSenior iOS Application Engineer - 26-10216Philadelphia, PAThis role requires deep hands-on .NET MAUI/iOS engineering expertise , strong problem-solving skills, and the ability to independently deliver complex application enhancements within an enterprise environment. The consultant will work closely with Product, Engineering, Architecture, Cybersecurity, Infrastructure, and business stakeholders to deliver secure, reliable, and high-performance functionality for field operations.
NewSenior Backend Software Engineer - 26-10222 Compu-Vision - ITSenior Backend Software Engineer - 26-10222Philadelphia, PAThe role requires strong expertise in .NET, C#, cloud-native development, secure APIs, workflow automation, enterprise integration, data engineering, DevOps, and production support . The consultant will work closely with Product, Engineering, iOS, QA, Infrastructure, Cybersecurity, Data, and Enterprise Integration teams to deliver secure, scalable, and production-ready backend solutions.
NewSenior UC Engineer MiratechSenior UC EngineerPhiladelphia, PAThe role focuses on Cisco Webex Calling, Webex Contact Center, Voice Recording, Trading Turret (IPC Connexus), Telecom Service Provider relationships, and SIP Trunking, working closely with business units and stakeholders to ensure platforms remain reliable, secure, and well supported. The role also involves supporting Red Sky (E911) emergency calling services and Microsoft Teams Meetings, monitoring platform health through observability and logging tools such as Splunk, and managing Call Detail Records (CDR) for reporting, troubleshooting, and compliance purposes.
NewSenior Systems Engineer ArctiqSenior Systems EngineerBlue Bell, PAArctiq is a global, intelligence-driven technology services company delivering professional and managed services across Hybrid Cloud Infrastructure, Networking & Connected Experiences, Cybersecurity, Data & AI, Autonomous Operations & Intelligence, and Enterprise Service Management. Collaborate with the team to design, implement, and manage the firm's core systems, including compute, networks, storage, Exchange, physical and virtual servers, Active Directory and Group Policy, Certificate Services, authentication platforms, and remote access/mobility solutions.
Network Engineer - Power Systems (Ot) Schweitzer Engineering LabsNetwork Engineer - Power Systems (Ot)King Of Prussia, PA$84,200–$160,000 / yearHave experience with wired protection and control network communications systems, including TDM and Ethernet technologies, communications test sets and analyzers, time synchronization and distribution, and industry network design and security practices. Maintaining and improving knowledge of power systems communications such as fiber links, radio connections, IP systems, switches, routers, LAN/WAN networks, servers, and TCP/IP.
NewElectronic Hardware Design Engineer Cornelis Networks IncElectronic Hardware Design EngineerWayne, PARemoteKey Responsibilities: Collaborate with software engineering, mechanical engineering, and marketing to develop Platform level architectures and board level design requirements, schedules, and cost targets. In addition to your base pay, you'll have access to a broad range of benefits, including medical, dental, and vision coverage, as well as disability and life insurance, a dependent care flexible spending account, accidental injury insurance, and pet insurance.
Software Engineer II Bentley Systems IncSoftware Engineer IIExton, PAOur team builds the embedded 3D/digital-twin viewer and its surrounding feature modules - used by engineers, owners, and contractors worldwide to review, markup, and collaborate on infrastructure projects (buildings, bridges, roads, rail, and utilities). Youll work in a modern TypeScript/React codebase built on iTwin.js and Cesium rendering large-scale iModels, Reality Data, and Geospatial Data in the browser, and surfacing that data through rich workflows.
Senior Mechanical Engineer - Aviation Burns EngineeringSenior Mechanical Engineer - AviationPhiladelphia, PennsylvaniaSeeks guidance from the Senior Engineers, Principal Engineers and Chief Engineers to develop complex engineering solutions and makes independent decisions to develop solutions of low to moderate complexity. Professionally Licensed Engineer with a Bachelor's (B.S.) Engineering degree with a minimum of 10 years related experience and/or training; or equivalent combination of education and experience.
Senior Mechanical Engineer - Rail & Transit Facilities Burns EngineeringSenior Mechanical Engineer - Rail & Transit FacilitiesPhiladelphia, PennsylvaniaSeeks guidance from the Senior Engineers, Principal Engineers and Chief Engineers to develop complex engineering solutions and makes independent decisions to develop solutions of low to moderate complexity. Professionally Licensed Engineer with a Bachelor's (B.S.) Engineering degree with a minimum of 10 years related experience and/or training; or equivalent combination of education and experience.
Senior Mechanical Engineer - Power & Utilities Burns EngineeringSenior Mechanical Engineer - Power & UtilitiesPhiladelphia, PennsylvaniaSeeks guidance from the Senior Engineers, Principal Engineers and Chief Engineers to develop complex engineering solutions and makes independent decisions to develop solutions of low to moderate complexity. Professionally Licensed Engineer with a Bachelor's (B.S.) Engineering degree with a minimum of 10 years related experience and/or training; or equivalent combination of education and experience.
Principal Software Engineer - Java Platform Engineering - US Oracle CorpPrincipal Software Engineer - Java Platform Engineering - USPhiladelphia, PA$99,600–$223,400 / yearOracle maintains broad salary ranges for its roles in order to account for variations in knowledge, skills, experience, market conditions and locations, as well as reflect Oracle''s differing products, industries and lines of business. Youll work on distributed systems, Kubernetes, applied AI, and highly resilient healthcare infrastructure with the autonomy to influence architecture, engineering direction, and product strategy.
Environmental Engineer III AECOMEnvironmental Engineer IIIConshohocken, PAWe invite you to bring your bold ideas and big dreams and become part of a global team of over 50,000 planners, designers, engineers, scientists, digital innovators, program and construction managers and other professionals delivering projects that create a positive and tangible impact around the world. The successful candidate will be committed to the team''s success and growth; will rigorously apply safety policies and procedures; will manage the technical, cost and schedule elements of project delivery; and will effectively manage the quality of field efforts and project deliverables within the bounds of the AECOM Quality Management System.
Google Cloud (AGBG) Sales Engineer Accenture PlcGoogle Cloud (AGBG) Sales EngineerPhiladelphia, PAOur AGBG professionals deliver a full stack of integrated cloud capabilities across data, edge, integrated infrastructure and applications, deep ecosystem skills, culture of change along with a deep industry expertise to shape, move, build and operate our clients' businesses in the cloud. You will partner with mid-market companies to design and implement transformative solutions on the Google Cloud platform, ensuring that technology decisions are directly tied to measurable value and long-term success.
Data Engineer CONTACT GOVERNMENT SERVICESData EngineerPhiladelphia, PA$112,597.33–$152,810.66 / yearCGS is seeking a passionate and driven Data Engineer to support a rapidly growing Data Analytics and Business Intelligence platform focused on providing solutions that empower our federal customers with the tools and capabilities needed to turn data into actionable insights. Achieve technical excellence by advocating for and adhering to lean-agile engineering principles and practices such as API-first design, simple design, continuous integration, version control, and automated testing.
Data Architect / Quality Assurance Engineer City of Philadelphia PAData Architect / Quality Assurance EngineerPhiladelphia, PASome examples of OIT's commitment to serving the public through the effective and innovative integration of City open data include: https://Atlas.phila.govhttps://property.phila.govhttps://Openmaps.phila.govhttps://streetsmartphl.phila.gov/www.phila.gov/solarmapwww.phila.gov/stressmapEssential Experience savings of 10% to 40% on your educational expenses, extending not only to City employees but in some cases, spouse and dependents too!*The successful candidate must be a city of Philadelphia resident within six months of hireEffective May 22, 2023, vaccinations are no longer required for new employees that work in non-medical, non-emergency or patient facing positions with the City of Philadelphia.
C++ Software Engineer (Senior, Staff, Or Lead) Ghost RoboticsC++ Software Engineer (Senior, Staff, Or Lead)Philadelphia, PA$135,000–$185,000 / yearHands-on command of modern C++ concepts: RAII, smart pointers, move semantics, templates and generic programming, concurrency primitives and thread safety, and clean API and library design. Our work spans perception, control, and systems software, and we value clean design, maintainability, and engineering rigor as much as raw performance.
OPENTEXT / NETIQ INFRASTRUCTURE ENGINEER Compu-Vision Consulting Inc.OPENTEXT / NETIQ INFRASTRUCTURE ENGINEERPhiladelphia, PAThis person must be comfortable working independently, participating in architecture discussions, troubleshooting complex infrastructure issues, documenting environments for compliance and disaster recovery, and supporting after-hours production activities when required. The ideal candidate will have deep enterprise-level experience supporting identity and access management platforms, directory services, authentication technologies, Windows infrastructure, and hybrid cloud environments.
NewElectrical Engineer – Mission Critical (Healthcare & Pharmaceutical Projects) JobotElectrical Engineer – Mission Critical (Healthcare & Pharmaceutical Projects)Philadelphia, PARemote$115,000–$145,000 / yearMust have Strong Conceptual Design Experience in REVIT for Engineering Consulting Firms specializing in Life-Science Projects: Hospitals, Laboratories, Pharmaceutical, FDA Regulated Sterile Environments, cGMP, Clean-Rooms, etc. Information collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal.
NewAV Engineer JobotAV EngineerBroomall, PA$80,000–$130,000 / yearInformation collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal. Strong project management skills, with the ability to manage multiple projects simultaneously and meet tight deadlines.
Project Engineer - Life Science Construction JobotProject Engineer - Life Science ConstructionBlue Bell, PA$65,000–$100,000 / yearInformation collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal. By applying for this job, you agree to receive calls, AI-generated calls, text messages, or emails from Jobot, and/or its agents and contracted partners.
Civil Project Engineer JobotCivil Project EngineerPhoenixville, PA$80,000–$150,000 / yearInformation collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal. Responsibilities will include but are not limited to the design and permitting of construction plans for site layout, grading, drainage, erosion control, stormwater treatment and conveyance, water and sewer, roadway, pump station and force main design.
Sr. Electrical Engineer JobotSr. Electrical EngineerValley Forge, PA$110,000–$200,000 / yearInformation collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal. They focus on keeping electrical equipment safe, reliable, and efficient, offering expertise in power system engineering, field services, and training.
Field Engineer Keller North America, Inc.Field EngineerPhiladelphia, PA$65,000–$85,000 / yearKeller is an excellent fit for a candidate who decided to become a civil engineer to work in Construction that includes a balance of design and construction management with a combination of field and office work. By connecting global resources and local experience, Keller develops innovative, practical, and cost-effective solutions to geotechnical challenges.
Project Engineer Keller North America, Inc.Project EngineerPhiladelphia, PA$83,000–$95,000 / yearFinancial Management • Analyzes targets and goals, job cost summaries, and other reports.• Creates and obtains approval of the initial budget and subsequent updates/changes.• Reviews weekly job cost summaries and advises the Project Manager.• Collaborates with pre-construction and the project team to manage the job transition process, communicate project requirements, and develop the initial procurement plans and budgets.• Alerts the Superintendent and Project Manager of potential project impact relating to resource management, crew make-up/size and other essential items pertaining to the project.
Railway Engineer - Remote Teoresi GroupRailway Engineer - RemotePhiladelphia, PARemoteIntegration of onboard and wayside subsystems, including signaling components, sensors, communication interfaces, and control units, into system-level testing environments (e.g., HIL/SIL). At Teoresi, we specialize in supporting companies in creating projects using cutting-edge technologies such as self-driving cars and nanotechnology for the medical field.
NewSenior Systems Engineer JobotSenior Systems EngineerPhiladelphia, PA$115,000–$145,000 / yearOur client is a global leader in commerce technology, delivering highly secure transactional, identity, and data solutions to many of the world's largest retailers, hospitality brands, healthcare organizations, financial institutions, and entertainment companies. Information collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal.
NewSenior Software Engineer JobotSenior Software EngineerPhiladelphia, PARemote$150,000–$200,000 / yearInformation collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal. This individual will play a key role in delivering high-impact, cloud-based solutions and driving technical best practices across the engineering team.
Snowflake Data Engineer JobotSnowflake Data EngineerPhiladelphia, PA$120,000–$155,000 / yearOur client is a rapidly growing enterprise software company undergoing a major cloud modernization initiative focused on building scalable, high-performance data platforms that support mission-critical business applications. Information collected and processed as part of your Jobot candidate profile, and any job applications, resumes, or other information you choose to submit is subject to Jobot's Privacy Policy, as well as the Jobot California Worker Privacy Notice and Jobot Notice Regarding Automated Employment Decision Tools which are available at jobot.com/legal.
Steel Connection Design Engineer GpacSteel Connection Design EngineerPhiladelphia, PA130000–175000We are partnering with a well-established and growing structural steel organization seeking a motivated engineer to lead connection design efforts on a wide variety of commercial, industrial, and institutional projects. GPAC (Growing People and Companies) is an award-winning search firm specializing in placing quality professionals within multiple industries across the United States since 1990.
Civil Structural Engineer GpacCivil Structural EngineerWillow Grove, PA95000–145000The ideal candidate enjoys solving complex engineering challenges, collaborating with multidisciplinary teams, and producing practical, efficient designs that meet client objectives. GPAC (Growing People and Companies) is an award-winning search firm specializing in placing quality professionals within multiple industries across the United States since 1990.
Electrical Engineer Chemours CoElectrical EngineerNewark, DE$110,544–$172,725 / yearThe 340 scientists, engineers, and technicians at the site work in 130 laboratories, an electrical cable prototyping line, and 15 chemical process enclosures/barricades that provide 320,000 square feet of space for research and development, technical service, and manufacturing support of Chemours businesses. The Chemours Newark Area Technology organization is seeking to engage an Electrical Engineer to support collaborative R&D projects, Pilot Operations, and Facility Management activities at three Chemours sites in the greater Newark, DE, area.
Entry Level Civil Engineer ArtheonEntry Level Civil EngineerCamden, New Jersey$65,000–$75,000 / yearWith expertise spanning civil/site engineering, environmental permitting, transportation infrastructure, construction management, and advanced surveying technologies, we are committed to delivering high-quality, timely solutions to local, state, and federal clients. Based in our Camden, NJ office, you will work alongside experienced engineers on progressively more complex assignments, developing technical expertise through structured mentorship and hands-on project experience.
AI/ML Software Engineer GE Aerospace.AI/ML Software EngineerPARemote$95,000–$140,000 / yearThe work involves using AWS tools to design and build AI-driven systems - not just training or fine-tuning models, but also crafting effective prompts, validating model performance through data analysis, and managing risks like hallucinations or bias. Healthcare benefits include medical, dental, vision, and prescription drug coverage; access to a Health Coach from GE Aerospace; and the Employee Assistance Program, which provides 24/7 confidential assessment, counseling and referral services.
Sr Design Engineer The Timken CoSr Design EngineerKing of Prussia, PAThis position requires the ability to engineer, design, analyze and select gear drive components and related systems using computer software for 3D modeling and internal calculation software to create new components, gears, shafts, housings and related systems to support new drivetrain and marine applications per customer requirements. The Design Engineer will develop detail part drawings and bill of materials, interact with service centers and customers, and provide technical support to other departments in the Timken Gears and Services network under the supervision and guidance of the Engineering Manager.
Special Systems Design Engineer McFarland JohnsonSpecial Systems Design EngineerPhiladelphia, PAMcFarland Johnson (MJ) is a 100% employee-owned (ESOP) engineering and infrastructure firm with decades of experience delivering complex projects across Aviation, Transportation, Environmental, Water/Wastewater, and MEP/Facilities sectors. Key Responsibilities: Develop and produce design drawings, specifications, and technical documents for special systems projects, including fire alarm, security/access control, communications, audio/visual, and low-voltage systems.
Entry Level Civil Engineer Trilon GroupEntry Level Civil EngineerCamden, NJ$65,000–$75,000 / yearWith expertise spanning civil/site engineering, environmental permitting, transportation infrastructure, construction management, and advanced surveying technologies, we are committed to delivering high-quality, timely solutions to local, state, and federal clients. Based in our Camden, NJ office, you will work alongside experienced engineers on progressively more complex assignments, developing technical expertise through structured mentorship and hands-on project experience.
MANUFACTURING ENGINEER TE Connectivity plcMANUFACTURING ENGINEERMiddletown, DE$84,300–$105,300 / yearAs a trusted innovation partner, our broad range of connectivity and sensor solutions enable the distribution of power, signal and data to advance next-generation transportation, energy networks, automated factories, data centers enabling artificial intelligence, and more. All legitimate job openings are posted exclusively on our official careers website at te.com/careers, and all email communications from our recruitment team will come only from actual email addresses ending in @te.com.
Structural Design Engineer (Civil/Truss) Illinois Tool WorksStructural Design Engineer (Civil/Truss)Any City, DE$70,000–$100,000 / yearWhy This Role Matters: This Structural Design Engineer role is essential because it sits at the intersection of engineering precision, construction efficiency, and customer success-directly impacting how safely and effectively buildings are designed and constructed. As a Structural Design Engineer at Alpine, you help translate complex engineering principles into practical, buildable solutions that optimize material use, improve productivity, and ensure structural integrity.
Structural Engineer STV Group IncStructural EngineerPhiladelphia, PA$104,402.58–$119,317.24 / yearThe successful candidate will support the design and delivery of structural systems for a diverse portfolio of public and private-sector building projects, including transportation facilities, municipal buildings, federal buildings, healthcare facilities, and commercial developments - working alongside senior engineers, project managers, and architects throughout all phases of project development. At STV, you'll work alongside experienced engineers and industry leaders, gain exposure to diverse project types across multiple market sectors, and build a clear path toward future project management and engineering leadership opportunities.
Weld Engineer Rhoads IndustriesWeld EngineerPhiladelphia, PennsylvaniaRhoads’ capabilities enable our customers to achieve superior results by deploying our diverse, highly skilled workforce and fabrication capabilities across commercial, government and maritime projects, all backed by state‐of‐the‐art resources and a 100+ year legacy of leadership. In addition to our field service and project skilled labor, Rhoads has expansive shipyard facilities and over 300,000 square feet of heavy manufacturing space located in The Navy Yard in Philadelphia.
DevOps Engineer - Linux (Top Secret with agreement to obtain CI Poly) North Point TechnologyDevOps Engineer - Linux (Top Secret with agreement to obtain CI Poly)King of Prussia, PAThe engineer monitors and modifies the enterprise environment in an agile, highly flexible setting, engages third-party vendors to translate and integrate manual steps into the automated deployment process, and creates or modifies existing DevOps automation to correct errors and improve deployment capabilities. Duties include deploying and maintaining RHEL/SE Linux configurations through Red Hat Satellite and Ansible automation, working one-on-one with site administrators to troubleshoot automation and deployment issues, and installing software libraries that function within the RHEL/SE Linux environment.
Software Engineer - Java (TS/SCI Clearance Required) North Point TechnologySoftware Engineer - Java (TS/SCI Clearance Required)King of Prussia, PAIt enables users to search, discover, and retrieve imagery and other GEOINT data, while centrally managing collection, exploitation, dissemination, and production tasks across a broad network of commercial and national providers. • Identifying and correcting program errors, creating and maintaining development documentation, and analyzing system functionality to clarify program intent, output requirements, data inputs, techniques, and controls.
Structural Engineer GpacStructural EngineerPhiladelphia, PA90000–120000For more than 100 years, my client has been one of the nation's premier heavy steel construction contractors, specializing in structural steel erection, bridge construction, crane engineering, custom steel fabrication, and heavy industrial projects. If you're passionate about structural engineering, enjoy solving complex challenges, and want to work on projects that leave a lasting impact, please apply here or send your resume directly to Zac Lubin at zac.lubin@gmail.com.
Structural Engineer (SE - Civil/Truss) Illinois Tool WorksStructural Engineer (SE - Civil/Truss)Any City, DE$75,000–$120,000 / yearIn a high-volume production environment, this position enables scalable, accurate, and efficient design delivery, helping customers operate more productively while reinforcing Alpine's reputation as a trusted industry leader. Why This Role Matters: This Structural Engineer position is critical to Alpine's mission of delivering high-quality, reliable building component solutions that directly impact the safety, efficiency, and profitability of its customers.
Professional Civil Engineer GpacProfessional Civil EngineerPhiladelphia, PA100000–150000GPAC (Growing People and Companies) is an award-winning search firm specializing in placing quality professionals within multiple industries across the United States since 1990. This individual will play a key role in leading projects, managing internal teams, and serving as a trusted partner to clients.
Senior Structural Bridge Engineer (Technical Lead) ArtheonSenior Structural Bridge Engineer (Technical Lead)Berlin, NJ$125,000–$145,000 / yearAs a Senior Structural Bridge Engineer, you will lead the structural design and delivery of bridges, walls, and related transportation structures; oversee analysis and plan production; drive QA/QC; and coordinate with highway, traffic, geotechnical, and water resources teams as well as subconsultants and clients. Our structural group supports complex bridge programs—from replacements and widenings to retaining structures and staged construction—frequently for New Jersey Department of Transportation (NJDOT) and the New Jersey Turnpike Authority (NJTA).
Civil Engineer/Designer Davron LLCCivil Engineer/DesignerNorristown, PACIVIL ENGINEER/DESIGNER | LAND DEVELOPMENT | STORMWATER MANAGEMENT | STORMWATER | EROSION AND SEDIMENT CONTROL | UTILITIES COORDINATION | AUTOCAD | CIVIL 3D | PERMITTING SUPPORT | QA/QC UPDATES | MISSION-CRITICAL FACILITIES | FULL-TIME . Bring your civil design expertise to a mission-critical environment where 24/7 reliability matters and your work directly supports control centers, data centers, and industrial facilities.
Mechanical Engineer / Designer Davron LLCMechanical Engineer / DesignerNorristown, PAMECHANICAL ENGINEER | MECHANICAL DESIGNER | DRAFTSPERSON | HVAC DESIGN | ASHRAE/ANSI | AUTOCAD | REVIT | PE LICENSE | CONTROL CENTER | DATA CENTER | MISSION-CRITICAL FACILITIES | FULL-TIME . Build your future with a mission-driven engineering team based in Norristown, PA, delivering high-reliability HVAC design for control center, data center, and other critical environments.
Lead Software Engineer - Tax Product Development BDO USA PCLead Software Engineer - Tax Product DevelopmentPhiladelphia, PA$140,000–$210,000 / yearJob Summary: The Lead Software Engineer, Tax Product Development plays a critical role in designing and implementing complex features and solutions that support the tax practice and delivery of services to clients. The annual allocation to the ESOP is fully funded by BDO through investments in company stock and grants employees the chance to grow their wealth over time as their shares vest and grow in value with the firm's success, with no employee contributions.
Lead Software Engineer - Tax Product Development BDO International LtdLead Software Engineer - Tax Product DevelopmentPhiladelphia, PA$140,000–$210,000 / yearJob Summary: The Lead Software Engineer, Tax Product Development plays a critical role in designing and implementing complex features and solutions that support the tax practice and delivery of services to clients. The annual allocation to the ESOP is fully funded by BDO through investments in company stock and grants employees the chance to grow their wealth over time as their shares vest and grow in value with the firm's success, with no employee contributions.