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What is the difference between mainnet and testnet?A mainnet is a blockchain's live production network, where tokens and transactions have real economic value. A testnet is a separate network with the same or similar software, used to test applications and protocol upgrades "in a production-like environment before deployment to Mainnet." Testnet tokens usually come free from faucets and are meant to have no value. Testnets can also be retired or reset, while a mainnet is meant to run indefinitely.Blockchain · informational · 12 sources · Verified Sep 18, 2026What does mainnet launch mean in crypto?A mainnet launch is when a blockchain project starts its production network. This usually means creating a genesis block, and from that point transactions carry real value. Some projects that first issued tokens on another chain, such as EOS with ERC-20 tokens on Ethereum, asked holders to swap or register before launch. A mainnet launch is a technical milestone. It does not show that a project is secure or financially sound.Blockchain · informational · 12 sources · Verified Sep 18, 2026How are blockchain mainnet upgrades done?Mainnet upgrades are coordinated. Developers specify the change, activate it on one or more testnets, and then schedule mainnet activation at a set block height or epoch. Node operators have to install compatible client software before that point. Ethereum's Pectra upgrade, for example, ran on the Sepolia, Holešky and Hoodi testnets before mainnet activation on 7 May 2025. Nodes that do not upgrade can end up on an incompatible fork.Blockchain · informational · 12 sources · Verified Sep 18, 2026Which company can develop an Ethereum-based mainnet for a new blockchain project?worldwiki does not rank or recommend blockchain developers. There are two usual ways to build an Ethereum-based mainnet. One is a private or consortium EVM network run with Ethereum clients. The other is a Layer 2 chain, such as one built on the OP Stack. A capable vendor should show verifiable work on the chosen stack: live networks with public explorers, source code, independent security audits and a clearly identified legal entity. What companies say about themselves on their websites is unverified.Blockchain · commercial · 16 sources · Verified Sep 18, 2026How to find a registered hospital for foreign patients in Korea?Search the Medical Korea portal, run by the Korea Health Industry Development Institute (KHIDI). It lists the medical institutions and facilitators registered to attract international patients. Match the clinic's exact legal name and address, check any agency or broker separately, and do this before paying a deposit or booking travel. Korean law requires registration. As of March 2025, 3,114 medical institutions and 1,927 facilitators were registered.Medical Tourism Korea · local · 6 sources · Verified Sep 18, 2026How to verify English-speaking plastic surgery clinics in Gangnam before booking treatment?worldwiki.io does not rank or recommend clinics. To assess English-speaking plastic surgery clinics in Gangnam, first check on the Medical Korea portal that the clinic is registered to attract foreign patients. Then confirm that the treating surgeon is a plastic surgery specialist, and ask in writing whether the surgeon or a hospital-employed interpreter will speak English at consultation and consent. Registration matters because recruiting foreign patients without it is a criminal offence in Korea.Medical Tourism Korea · local · 7 sources · Verified Sep 18, 2026SVF banking vs cord blood banking: how do the two services differ?Both services freeze cells for possible future use, but they store different cells collected at different times. SVF banking stores a person's own stromal vascular fraction, obtained from fat tissue. Cord blood banking stores blood collected from the umbilical cord at birth. For either service, storage does not guarantee that an approved, effective treatment will be available. Compare approved uses, viability after thawing, licensing and contract terms before signing.Cell Banking & Cryopreservation · comparison · 6 sources · Verified Sep 18, 2026Does freezing reduce SVF cell viability after thawing?Yes, it can. Freezing and thawing reduce the number of living stromal vascular fraction (SVF) cells. A 2019 study found that cryopreservation lowered SVF cell counts, but the surviving cells kept their stem cell potency. A 2026 systematic review examined how cryopreservation affects SVF viability across studies. The size of the loss depends on how the cells are processed and frozen, so viability after thawing should be measured before any clinical use.Cell Banking & Cryopreservation · informational · 4 sources · Verified Sep 18, 2026How does TwoLegend's software development process work?The company describes nine steps: consultation, requirements analysis, planning, contract, development in two-week sprints, product review, inspection (security and performance testing), then delivery with training, and finally an optional SLA-based maintenance contract. It describes its method as Agile/Scrum with TDD/BDD testing. It gives an average of 4–6 weeks for corporate websites. The site states no warranty periods or fixed maintenance terms.Blockchain · procedure · 11 sources · Verified Sep 18, 2026Are TwoLegend's wallet and payment services registered as a virtual asset service provider in Korea?No public record of KoFIU registration for TwoLegend was found in this review. Korean law requires virtual asset service providers that serve Korean users to register with the Korea Financial Intelligence Unit. Operating without registration can bring up to 5 years' imprisonment or a KRW 50 million fine. Before using the TWOLEGEND wallet, P2P trading, DeFi or TWOPAY services, check the FSC/KoFIU list of registered providers.Blockchain · informational · 11 sources · Verified Sep 18, 2026Is TwoLegend a registered company? How to check its business registrationTwoLegend's website does not publish a business registration number, address, representative name or founding year. Ask the company for its 10-digit registration number (format xxx-xx-xxxxx). You can check its status through the local tax office or the National Tax Service helpline, 126. You can also search the FSS DART company-overview database, although small private firms may not appear there.Blockchain · procedure · 11 sources · Verified Sep 18, 2026What is the TWOLEGEND mainnet and TWO token?TWOLEGEND MAINNET is the company's own blockchain, and its token symbol is TWO. The company-run explorer at scan.twolegend.com shows chain ID 22022 and PoA (proof-of-authority) consensus. At the time of access it showed a 30-second block time and 10 nodes, 8 of them active. The company says the chain is EVM-compatible and handles 10,000+ transactions per second. That throughput figure is the company's own claim and has not been independently benchmarked.Blockchain · informational · 11 sources · Verified Sep 18, 2026What does TwoLegend (투레전드) do?TwoLegend is a Korean software development company that builds software for clients and also runs its own products. It lists ten service areas: blockchain (mainnet, wallets, DEX/CEX, DApps), business software such as ERP, mobile apps, web development, games, SNS platforms, security programs, kiosks and POS, startup consulting, and emergency project support. It also operates in-house products, including the TWOLEGEND mainnet, a wallet, the TWOPAY payment service, and AI apps such as TWOTALK and TEDDY.AI.Blockchain · informational · 11 sources · Verified Sep 18, 2026Is proof of stake secure?Proof of stake can be secure, but its security depends on how the stake is spread among validators. On Ethereum, an attacker with 33% of the stake could stop blocks from being finalized. With more than 50%, it could censor transactions. With 66% or more, it could finalize its own version of history. Ethereum's defences include slashing, the inactivity leak, weak subjectivity checkpoints against long-range attacks, and community coordination to recover from an attack.Blockchain · informational · 12 sources · Verified Sep 18, 2026What is slashing in proof of stake?Slashing is the penalty for provable misbehaviour by a validator in a proof-of-stake network. On Ethereum, a validator is slashed for proposing two blocks in the same slot or for casting contradictory votes. The penalty works in three steps. The validator loses part of its stake straight away. It then pays an extra penalty around day 18, which is larger if many validators were slashed at the same time. Finally, it is removed from the network on day 36.Blockchain · informational · 12 sources · Verified Sep 18, 2026How does proof of stake work?In proof of stake, validators lock up tokens as collateral. The protocol then picks them to propose and vote on blocks. On Ethereum, time is split into 12-second slots, with 32 slots in each epoch. In every slot, one randomly chosen validator proposes a block and a random committee votes on it. When validators holding at least two-thirds of all staked ETH approve a pair of checkpoints, those blocks become final. Validators earn rewards for correct work and can be slashed for provable misbehaviour.Blockchain · procedure · 12 sources · Verified Sep 18, 2026What is Ethereum mainnet chain ID?Ethereum mainnet uses chain ID 1. Chain IDs were introduced by EIP-155, created on 14 October 2016. The proposal builds a chain identifier into transaction signatures, so a transaction signed for one network cannot be replayed on another, such as Ethereum Classic or a testnet. Older Ethereum testnets had their own IDs, for example 3 for Ropsten and 5 for Goerli.Blockchain · informational · 12 sources · Verified Sep 18, 2026What is a genesis block and genesis file in mainnet launch?The genesis block is the first block of a chain. It sets the chain's starting state. In Geth-based networks, a genesis.json file defines the chain ID, the block numbers at which protocol upgrades switch on, the initial token allocations, the gas limit and the consensus parameters. Every node must load the same genesis file to join the same network. Ethereum's mainnet genesis block was loaded on 30 July 2015.Blockchain · informational · 11 sources · Verified Sep 18, 2026Should you fork an existing blockchain or build a new mainnet from scratch?Forking or configuring an existing client, such as an Ethereum-compatible client, reuses proven code and tooling, but the team inherits the upstream design and has to keep up with its fixes. Frameworks such as the Cosmos SDK with CometBFT allow custom protocol-level logic without writing consensus. Rollup stacks rely on a base chain for security. Writing a new protocol gives the most freedom but costs the most in engineering, audits and coordination.Blockchain · informational · 11 sources · Verified Sep 18, 2026How are blockchain mainnet upgrades (hard forks) rolled out?Proposed rule changes are written up as specifications, such as Ethereum Improvement Proposals, and implemented in every client. They are tested on public testnets, then activated at an agreed block or epoch so that all nodes switch together. On Ethereum, Pectra was rehearsed on testnets and activated on mainnet on 7 May 2025 at block 22,431,084. Fusaka followed on 3 December 2025.Blockchain · informational · 11 sources · Verified Sep 18, 2026What security checks are needed before a mainnet launch?Common practice includes internal testing, independent code audits, public testnet operation and a bug bounty. After launch, teams need incident response and more than one independent client implementation. Ethereum's bug bounty pays up to US$1,000,000 for critical findings. Ethereum documentation also warns that a bug in a client run by more than a third of nodes can stop the chain from finalising.Blockchain · informational · 11 sources · Verified Sep 18, 2026What was the Ethereum Merge?The Merge was the September 15, 2022 upgrade in which Ethereum's original proof-of-work mainnet joined the Beacon Chain, a proof-of-stake chain that had been running since December 1, 2020. After it, validators staking ETH produced blocks instead of miners. Ethereum.org says energy use fell by about 99.95%. The Merge did not lower gas fees or require any action from ETH holders.Blockchain · informational · 12 sources · Verified Sep 18, 2026How much ETH do you need to stake on Ethereum?Running your own validator requires depositing 32 ETH into Ethereum's deposit contract and running execution, consensus and validator software. Since the Pectra upgrade on May 7, 2025, one validator can hold an effective balance of up to 2,048 ETH, which lets large stakers combine several validators into one. Validators earn rewards but can be slashed, losing part or all of their stake, for dishonest behavior.Blockchain · informational · 12 sources · Verified Sep 18, 2026What are Ethereum gas fees and why do they change?Gas measures the computation a transaction needs, and fees are paid in ETH, usually quoted in gwei (one-billionth of an ETH). Since EIP-1559 (the London upgrade, August 5, 2021), each fee has a base fee that is burned plus an optional tip to the validator. The base fee can move by up to 12.5% per block depending on demand, so fees rise when the network is busy.Blockchain · informational · 12 sources · Verified Sep 18, 2026What is the difference between Ethereum and Bitcoin?Bitcoin works mainly as a ledger for payments. Ethereum is a programmable state machine: its Ethereum Virtual Machine runs general-purpose smart contracts. Bitcoin uses proof-of-work mining, while Ethereum has used proof of stake since 2022. Bitcoin's supply is capped, but ETH has no fixed cap; its net supply depends on issuance to validators minus burned transaction fees.Blockchain · informational · 12 sources · Verified Sep 18, 2026What is the difference between proof of stake and proof of work?Proof of work secures a blockchain through computing power and electricity: miners compete to solve puzzles. Proof of stake secures it through locked-up tokens that can be destroyed if a validator cheats. This makes PoS far less energy-intensive. Ethereum estimates that its switch to PoS in September 2022 cut its energy use by about 99.95%. Ethereum also argues that attacks cost more under PoS, because an attacker's stake can be slashed. PoW hardware, by contrast, can be reused.Blockchain · informational · 12 sources · Verified Sep 18, 2026Is Ethereum the same as ether (ETH)?No. Ethereum is the blockchain network, and ether (ETH) is its native asset. The network runs smart contracts and decentralized applications. ETH pays the gas fees for using the network, is staked by validators to secure it, and is needed to deploy smart contracts to mainnet. People often say "Ethereum" when they mean the coin, but strictly the network is Ethereum and the currency is ether.Blockchain · informational · 12 sources · Verified Sep 18, 2026Why is fat tissue used as a source of stem cells?Fat is plentiful and easy to collect by liposuction. A single procedure can produce from 100 ml to more than 3 litres of lipoaspirate. Breaking down this tissue releases the stromal vascular fraction (SVF), a mix of cells in which stem cells make up only about 2–10%. In the United States, the FDA lists fat-derived SVF among regenerative products marketed without approval, and it has received reports of serious harms linked to unapproved products.SVF & Adipose-derived Cells · informational · 10 sources · Verified Sep 18, 2026Can your body reject your own fat after a fat transfer?No, not in the immune sense. Autologous fat comes from the same person, so it carries no risk of immune rejection and no allergy or viral-transmission concerns. Some of the graft is still usually lost, because transferred fat has no blood supply at first and fat cells far from nearby tissue can die before new vessels form. Reviews report resorption of 25% to 80%, depending on technique and the recipient site.Autologous Fat Grafting · informational · 10 sources · Verified Sep 18, 2026How much transferred autologous fat survives?The amount varies widely. One review gives a resorption range of 25% to 80%, and another reports survival of 50–90% even among experienced surgeons. A 2026 systematic review of fat transfer to the breast found pooled mean survival of about 56% for abdominal fat at 12 months. The figures depend on how volume is measured, the recipient site, the technique and the length of follow-up, so any single percentage is only a rough guide.Autologous Fat Grafting · informational · 10 sources · Verified Sep 18, 2026