CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgZmlsbD0ibm9uZSI+PHBhdGggZmlsbD0iI0IyMEYwMyIgZD0iTTE2IDNhMTMgMTMgMCAxIDAgMTMgMTNBMTMuMDE1IDEzLjAxNSAwIDAgMCAxNiAzbTAgMjRhMTEgMTEgMCAxIDEgMTEtMTEgMTEuMDEgMTEuMDEgMCAwIDEtMTEgMTEiLz48cGF0aCBmaWxsPSIjQjIwRjAzIiBkPSJNMTcuMDM4IDE4LjYxNUgxNC44N0wxNC41NjMgOS41aDIuNzgzem0tMS4wODQgMS40MjdxLjY2IDAgMS4wNTcuMzg4LjQwNy4zODkuNDA3Ljk5NCAwIC41OTYtLjQwNy45ODQtLjM5Ny4zOS0xLjA1Ny4zODktLjY1IDAtMS4wNTYtLjM4OS0uMzk4LS4zODktLjM5OC0uOTg0IDAtLjU5Ny4zOTgtLjk4NS40MDYtLjM5NyAxLjA1Ni0uMzk3Ii8+PC9zdmc+);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="120"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "publications.waset.org",cType: 'non-interactive',cRay: '9135c0d22da4cdfa',cH: 'jkLT13TFvFf7gD1fKUWq3kvYUMsTSsgH4UV68pgnN.U-1739795054-1.2.1.1-8RO4ApxxRk_rBEQWkOsothNzNNzvI7Fa.T0gIn1fTfDW1FtHNeRUS4nET8SrlkoO',cUPMDTk: "\/search?q=PET&__cf_chl_tk=oqkFiVHBHYlaiO4esHlH15iE.rphcgt2IlL_YrJPtkk-1739795054-1.0.1.1-5JqMjpfUM56kSDU3BmS8AaB4RRJYSWhCLEg1U7LqYyk",cFPWv: 'b',cITimeS: '1739795054',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/search?q=PET&__cf_chl_f_tk=oqkFiVHBHYlaiO4esHlH15iE.rphcgt2IlL_YrJPtkk-1739795054-1.0.1.1-5JqMjpfUM56kSDU3BmS8AaB4RRJYSWhCLEg1U7LqYyk",md: "XBVhYi1r2ktxm9gq6FMzGrRAs7OlL_MRAhJml25KVPM-1739795054-1.2.1.1-eXuOADS3qqvpYalEuEm2F7NaoTMeNn06b.lXX3BtJ7e5mXn8CmurC1eAnw.GI3wgDLJOgmnIiOPr.sU.PuLkKYZCDp.Zkdx0AvGOR6caBQrLvBvMF6NfWkZXjfE4a0_xjDTiaWziSCHNZ0seT3VBJfuRDCWyGNKCNIdQMEqvsF_f8fqWgonubtUI_a.2C6iVLX.iREZHbjZSlEche7P6TYBqDyKLzwIAxPVC7lM3WmVvYWgzI15GrwA4UyGKUz.3GxamdeUV.7UxBRvJYwCD6W1DLe1ff__S6e792Y9Xxa7r_5ir.z.IeNHVKtrvRa1fFPg4rAllGDbyTjXI6qm2Elu8Rp8LtJC.AzB7qrO7K4HW8qXXAw_33FG0dx.pVL99LQ9LUKqInUM46pdK91mTD3Kal..XGXnsseIrNmQCI3GqNX13Zz5ZgFa58xDT2HWO23HZxltSsjdz.UvB2sLzj5_NXajoNjZsKwZbUZ8pxdeftG1qmEQTxhHu0p8JY.iObdTBGnNtcTg5cWu8zCMc5fQymjHPvJrBWNRs.PgWAf321KwQxhguI6bLeoA9wNR.FtDZvdS2d891duwB78JuLU7mw_deEByuLzULWm41RCfz0.Tkf59YvotNBKv1CRyvcds3Zr1ZohFaxsPeTrOjoVn7qBFUyjuEAs2ChUB2kWyC0FCF4BE4Kkf3xsuZ6vYca7CiV5FTf_wsL3lnd5V.eDvpV33Ch3PWDxDeuHuB99TMDLg2eZilDYf3el3WvjXZI15pU9GnqQNOktD3GZ22LhhSNM8zf05DwEXl.SkCc1PaY5Ys35IQMQ6RXBaTUSR7_hKQblmZY0mnRyCwaPRRYHZDwz375.iXla3UMtfz1W8QjoRpjn3747HcGsqYFf0UbH8TnL0XvFh2ztDTMT8qbtHOSNpALeQwL873bF_epwyIZmD5Kx8V4d_HUf5NPoJMQe.JxnNHrw6VYSmL8.1gNgHrnfhRj5xbodzi0P4WMnfrP8k0p.I4JCNn4Yy4ZTs6dTttL.M_5Q8M9dXGt1.pGot7plMA9rhPCr79WrZrJLiXwvfml4zG_0IWYiCZc6sWYtMG0tYalYTvEPS3ZBpj26uXwdR0JLCzGT13hKC1Rr5Y5rvWuEqa_hAHGm94X7k3l5jspvAREoSOACCQrW22Loq8PypVrJXrvpugUIApbafd0igBLkFRgqS9Q.DCodNdOmt2k6fUVAkXzBEpSF2FPT1Ef6PK.pDvsGiI74JLKgt3r6e3wYj5jJETUu8nQx_vwFShYYqUT7VMiyF8oECN5YkOcmimnGJM88zskdbghGrhX.BeYBHHEUBdrf4Uvd4gzqcSlbchfReLmsQ.rAXhp.ItPOMHk9h3u.Jvxn9QYsPFF7K8UX0MXbyzQtbW9h9sK4cRyA8UI.n7jLvm96r.AXLCg9h3A25eEBKqKEF4eyMuUdKHCIGte98p9mUnkPtFkuLfUR_I1WKminqn0NdlFa.7zgd5yJa5TeLTwPH53hCK9nel2EmoN3_H_9WYPRjOIGmnCUDNUI_FoMPN7255wUKizCjoLDXU0tm14bycXkxbV2.a3H2Y9t9ukuTVse6w7CVdIAOPMgaEMuQDJ3B5BhTMEQ1uVmdYdEda0_MJ3FIbnnOr03mqPqib5nQKGgxC9pQnVGIJYcWpaBHNh83wS8vbh8wv9O_pTzynZoMpHCGYK26TLF5LMw4LcwO3GctgO4dtxknGV.0VXti1UUtMlkrkWdQMLzCOO9Zggqt3K7W_h2E3sflLKfSif8unDkDFM7Kz7mHXG2mwSm3pfBacsxG__cvyNH21yI9AIF0iBDZQj19Y26WOB4K05T2k8IBCD9RzC3ghareJtemoRazdaDI9Y1XCg4Cl0AeP5pGXy8U",mdrd: "cEoRDwgvFF5O9T9J234MkvI_uUdKLbVN_Jg1FE4YUOU-1739795054-1.2.1.1-ew41X9i8XKz6__bA4ZmHUi.i.D23GXD6faKNA7q9cI_.kqfFXhAfqEtiBQPC0Cbu_BdCfMS21mitAPYWbHAk57qzxD51jDBjKwNF7VSt1LrLT0na3QWP5DbT6ZTZ3TbVHhGUnNmMlpbijFiSj9uGgLw7QyUD5bNQrdECMevCC_TZZALrKVDlL6qUfWduDSoKbMPjhsBas0i.mH2BF5qkFNmL0ieYxdC_qRCFwwLS1blhVyfCmbzYyGfpGG5lz1eUbKzw80xN6M3nhj3w2rGSGKuz.QwePWxBSlXG4h5BMZ2HAbvbioSo4f4iLe.6Fi63Yw6sw7Gi9L_olm.l7ivGZjN3seBjmbpjZ6tC6mPYy5iaIksOurxzjq9Ogs5BXVEryqM0rkvke9UREiEUucJx8goLwE1jmUGJi0Qj8WB3vTG8jhMvSyyym01t5w07J2W4LZidQa7Bb0DXPHPMMkjhPtDsxDoR2UYDrPG.8Ifl2wyp.PLZ.DsZUegFYqHO8vc9fK44o_3OoqS858WNALn0U50C385tNrwnF2q8ggFqOHM3Gvj2zTMe02ewJsRbg83E1i9r3XIcxn5GTqjpzOwi_Y34gws2fbHlG.ZnkTeoVtQ7ICVVD9lWnYFsuHezhvW1lMr6C1hv4QjMkQHzA26lN14kjomyHMKohuOWfsPhXiO.ge1RjuO1Rv3kUYHASOyUrGqp.O_JIohQFsjO7NJhyqZ5bInm.kVsRUsBPPVUFXWsEN.4XnuY3EU5RR0BW2mWeX1dVS0uG5NKOjXRYpvYGXp4IT4eX77jrFLTZXdMiRAKoC2efwzjD_43MpP0IXX5G7X1AN2CUy8lR.rH3GB4D60hOa7rj_EgLOlRYi5b.rEvcVKO34jvmcvmznjhGzIOhedjcVH10g_Cq6ESQ2OBu3kMKkowNRXO6vTm5H1MGh_FMNkyUfcDZmYe65X.OngDW.6eeJnuXJqQnRHG2RAETqWgKWiYkkqgk6KEqYfAobERPy0jTzz2DKKpU6cajEacZbh6U1xoQcP9k3tmicBSjL5WIrcTrkkjMxmdPkvTxKWRNHm0jz4kFiSEVSKEmnnqDBQfmbIEbIjxH1N5t_Ex.tIEXbhuAZxf02s1BaRSKnAln1mE7VyFpsjymdZ7If2NEw5nZoqHJ3hnZLzbgunFD_82IMopldlOK9bRYz6LRJsFUavHLeVGuPiiALR6s60TJrLRqL7IFYZbO2PfMBXnV7N25.vH38YR1Rzx7BQgA_tEWeHu6sAubFMEiFOWCOCB7UA6u31Vlx6NR8iTraTPSwmBkVys8FBBTGUrkqv2FQk.h57Q6YdEJv1X_gX3HXOnps6PXMZspL8bk1i3KWgfA6dw_49cEjvUiaMSLmbOTy3ffy_FgkeUvRxnxfDuzUKSGDMqUI3C1WedfLHRaTXxDFzXHePxmKdo9ndzKviOWKzca.qHPwa6l0Y9kQJhmYJH_X7cpwOrYPA8rda_Pthvz2dryBdvOZz63LdHBLRvHIF6Oe2CXJ6K.aNJFp0pV.LZlOXDjAJkCEEoJy1T_tG8mtljMFUUO9huOVnlknc0jmdLqsi0ENbHE..NwvHspyWddfd.gZqtrQV4rljwruICaY3JcIAkTwxEFHEbRUayqCjE48PMS5Zxy0sPJt2lh5Rryf_kvquyRbtmoD2RbESrNoc0a4ciVpwYVuIDKVbetaJYxlrd4.zBjdpxu8zLmbDNJCM_T.yD9MsdeYaatNEFtYpcvYmArlKTDO_7NvXC7pQwETecM6eI9XCNtnx7AloO.Eu4By9HYf7eRS8gFRfVvfRpYVbl8gNv1cgyCmClEOx3rSVzJgXeF_qVVz3.1.B_mLnbNAlVACR2Of4QjSdDK.nO8emDg6VajGbU7OQ7L9RKlI4lI4S420kEaG3VUMRLJIUUyAvqEvWj5hoZ27mIGKVl0jiLWw5atlmbZ64NwlK57qBnd_tKYhXa6FfHNbacnv061WQLf7DaGMK4eUp9tg"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9135c0d22da4cdfa';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/search?q=PET&__cf_chl_rt_tk=oqkFiVHBHYlaiO4esHlH15iE.rphcgt2IlL_YrJPtkk-1739795054-1.0.1.1-5JqMjpfUM56kSDU3BmS8AaB4RRJYSWhCLEg1U7LqYyk" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>