106,154 research outputs found

    Li–ion diffusion on the surface of Ti3C2-T (T=O, S, F, Cl, Br) MXene

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    K. A. Papadopoulou, D. Parfitt, A. Chroneos and S.-R. G. Christopoulos, “Li–ion diffusion on the surface of Ti3C2-T (T=O, S, F, Cl, Br) MXene”, European Materials Research Society Spring 2022 meeting, 30 May-3 June 2022, onlin

    Thermal Ageing Effects on the Residual Fatigue Strength of AA2618-T6511 Aluminium Alloy

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    This work presents the results of an experimental investigation on the effects of thermal ageing over the residual fatigue strength of AA2618-T6511 aluminium alloy. Among others, this kind of light alloy finds practical applications in highly stressed engine components, such as pistons, that are typically subjected to both thermal and fatigue loads. Thermal cycles are responsible for ageing phenomena, that involve the precipitation of silicates, with a corresponding progressive damage of the microstructure and weakening of the mechanical characteristics of the material. Artificial ageing has been reproduced in laboratory by means of thermal cycles controlled in time and temperature. These variables have been correlated to the hardness values measured on the surface of specimens. Bending fatigue tests have been performed on a rotating machine in a temperature controlled environment. The experimental S-N diagram is finally presented, as a function of the tested temperature, in order to provide a design tool for the fatigue life estimation of AA2618 components

    F-doped orthorhombic Nb2O5 exposed with 97% (100) facet for fast reversible Li+-Intercalation

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    Orthorhombic Nb2O5 (T-Nb2O5) is attractive for fast-charging Li-ion batteries, but it is still hard to realize rapid charge transfer kinetics for Li-ion storage. Herein, F-doped T-Nb2O5 microflowers (F-Nb2O5) are rationally synthesized through topotactic conversion. Specifically, F-Nb2O5 are assembled by single-crystal nanoflakes with nearly 97% exposed (100) facet, which maximizes the exposure of the feasible Li+ transport pathways along loosely packed 4g atomic layers to the electrolytes, thus effectively enhancing the Li+-intercalation performance. Besides, the band gap of F-Nb2O5 is reduced to 2.87 eV due to the doping of F atoms, leading to enhanced electrical conductivity. The synergetic effects between tailored exposed crystal facets, F-doping, and ultrathin building blocks, speed up the Li+/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb2O5. Therefore, F-Nb2O5 exhibit superior rate capability (210.8 and 164.9 mAh g−1 at 1 and 10 C, respectively) and good long-term 10 C cycling performance (132.7 mAh g−1 after 1500 cycles)

    A Study of the Thermodynamics and Kinetics of LiₓFePO₄ as a Cathode Material for Li Batteries

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    Olivine-type LiFePO4 has been recognized as one of the most promising cathode materials for rechargeable Li batteries. Its advantages include high capacity, high stability, nontoxicity, and low cost. Our methods for synthesizing nanocrystalline LixFePO4 with the olivine structure are described. Solid-state reactions and precipitation reactions were both successful, and ball milling was especially effective at reducing crystallite sizes. Diffractometry and microscopy were used to characterize these materials, and results of impurity phases, excess Fe3+, and internal stresses are reported for the different types of synthesis. Applications of lithium-ion batteries, including automotive applications, require fast kinetics and high conductivity of ions and electrons. Unfortunately, LixFePO4 has the electronic structure of an insulator, an entirely unsatisfactory situation if it is to be used as a battery electrode. Electrical conductivity in LixFePO4 occurs by the motion of small polarons, which are valence electrons at Fe atoms plus their distorted local environments. Electrical conductivity of LixFePO4 is interpreted in terms of small polaron hopping. There are other factors of importance in these measurements, such as impurities or defects that block the one-dimensional conduction channels of the olivine structure of LixFePO4. We studied the polaron hopping directly, which allows us to understand the intrinsic electrical conductivity, and how it depends on microstructure and composition of LixFePO4. The experimental technique was Mossbauer spectrometry, which has been used for many years as a means for determining the fractions of Fe2+ and Fe3+ in a material. Usually the spectral signatures of Fe2+ and Fe3+ are distinct. When valence electrons hop between Fe2+ and Fe3+ at a frequency of 108 Hz or higher, however, the valence changes during the timescale of the Mossbauer measurement and the spectrum is blurred. By measuring Mossbauer spectra at elevated temperatures, we can determine the fractions of Fe atoms participating in polaron hopping, and determine the activation energy of the process. From this we estimate intrinsic electrical conductivities of 10-7S/cm at room temperature for nanocrystalline Li0.5FePO4, for example. We find a comparable conductivity for LixFePO4 prepared as a solid solution, but the conductivity of conventional LixFePO4 is much lower. There has been much discussion about how surface area might thermodynamically stabilize the solid solution phase of nanocrystalline LixFePO4. In a series of X-ray diffraction measurements, some at elevated temperatures, we found the solid solution phase of LixFePO4 to be especially robust at room temperature when the material was prepared in nanocrystalline form. Moreover, the consistent phase transition temperature around 200°C was observed, as evidence for the unchanged equilibrium phase diagram by crystallite size. This is consistent with our evaluation on the boundaries of the two-phase mixture of triphylite and heterosite during Li insertion and extraction. Profiles of entropy and enthalpy changes were evaluated by open-circuit voltage measurements. The boundaries were found at x=0.05 and 0.95 in the LixFePO4 with crystal size of 70 nm, similar to the reported values on bulk-LixFePO4. These are important in practice, because electrochemical lithiation and delithiation at room temperature should remain as a two-phase transformation, even if a solid solution of lithium is present in the initial electrode material.</p

    Reciprocity and impact in academic careers

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    The growing importance of citation-based bibliometric indicators in shaping the prospects of academic careers incentivizes scientists to boost the numbers of citations they receive. Whereas the exploitation of self-citations has been extensively documented, the impact of reciprocated citations has not yet been studied. We study reciprocity in a citation network of authors, and compare it with the average reciprocity computed in an ensemble of null network models. We show that obtaining citations through reciprocity correlates negatively with an impactful career in the long term. Nevertheless, at the aggregate level we show evidence of a steady increase in reciprocity over the years, largely fuelled by the citations reciprocated between coauthors. Our results characterize the structure of author networks in a time of increasing emphasis on citation-based indicators, and we discuss their implications towards a fairer assessment of academic impact

    S T ABIL I T AS H ASIL P AD A G E NER ASI S E G REG ASI F 5 , F B E B E RA P A G E NOT I P E K E DEL AI

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    The e f for ts to incr e a se th e pr oduc ti on a nd p roduc t ivi t y o f so y be a n that c a n be a c hiev e d throu g h the use of im pr ov ing se e d qua li t y a nd incr e a s in g plant populations. B r e e din g a c ti vit ies c losel y a ssocia ted with plant se l e c ti on. On e of the purpo se of the se lec ti on wa s he ld to obtain stea dy p roduc ti vit y va ri e ti e s. S tabili t y test re sult s i s one metho d to test stra ins o f plant s, e spec i a ll y so y b e a n str a in that will be r e lea s e d int o a r e c omm e nde d va ri e t y . The e x pe rimen t wa s c onduc ted a t the e x pe rimen tal fie ld of the F a c ult y o f Agr iculture , The Univ e rsit y of Au g ust 17, 1945 B a n y uwa n g i , Ke ba len an , B a n y uw a n g i dist ric t , with a ± 43 mete rs a lt it ude a bove the se a l e ve l . Thi s stud y wa s con duc te d fr om F e br ua r y to J une 2012 . The m a ter ials that used i n th is stud y we r e : 9 kinds of ge not y p e s that Une j 1 , Une j 2, P oli je 1 , P oli je 2, P oli je 3, P oli je 4, Ma laba r , W il is a nd Ge pa k Kuning , P honska c ompound fe rtili z e r , pe sti c ides De c is 25 EC , Mar shall 200 C , lea f fe rtili z e r He rba fa rm , C o locr on a nd F ur a da n 3G . W hil e the tool s used on thi s re se a rc h a re me a surin g c ups, sc a les a na l y ti c , bu re tt e , dr ip , sc iss or s , spr ay tanks , buc ke ts, a nd sc iss or s c utt ing s . The e x pe rimen ts w e re c onduc ted to d e ter mi ne the stabil it y o f so y be a n y i e lds in th e g e n e ra ti on F 5 , F 6 a nd F of th e nine ge not y pe s w e r e teste d , na mel y Une j 1 , Une j 2 , poli je 1, P oli je 2 , P oli je 3, a nd P oli je 4 a s ge not y p e pr o mi sing li ne s a nd thre e str a ins c o mpar ison, na mel y Mala b a r , W il is a nd Ge pa k Kun ing . 7 This stud y used a ra n domi z e d c ompl e te bloc k de sig n (RCB D ) e a c h g e n e ra ti on , followe d b y a n a n a l y sis o f homo g e n e it y t e sti ng a nd stabil it y testin g a c c or din g to Ebe rh a rt a n d R ussell , invol ving nine so y be a n ge not y pe s wit h thre e re pli c a ti ons in the g e ne r a ti on F 5 , F 6 a nd F I f ther e is a sig nific a ntl y d iff e re n t re sult made S c ott Knott t e st at 5% leve l W e used t he homog e nit y a na l y sis : 1. C hi squar e test for homog e nit y r a n g e of e rr or , with B a rtlett ' s test , 2. Va lue of c hi squar e d test , 3. F test , s ig nific a nt diff e re n c e t e st a nd the int e ra c ti on e ff e c t of g ( g x s), 4. C ombine d analysis , a nd 5. S tabili t y Te st . T he r e sult s showe d th a t the stabil it y o f the re sult s of e a c h g e not y pe wa s influe nc e d b y g e n e ti c a n d e nviron menta l fa c tors a nd plant he ig ht. Th e number of pods se e d number , we i g ht pe r 100 se e ds, a nd se e d we i g ht. I t c a n be used a s se lec ti on c rite ria for so y b e a n y ield im pr ov e me nt pr ogra m. G e not y pe s teste d, turne d out to Une j 1, P oli je ge not y pe s 1, 2 a nd P oli je 3, showin g stabil it y in two pa ra mete rs on the obser va ti ons, whe r e a s the other g e not y pe s onl y on th e pa ra mete rs of obse rva ti o n onl y . I t c a n be c onc lud e d that Une j 1, P oli je g e not y pe s 1, P oli je 2 a nd P oli je 3 we re the sup e rior g e not y pe s. I t c a n be re c omm e n de d to be de ve loped a nd pr odu c e d in lar g e qua nti ti e s i n the c omm unit y . The other g e not y p e s, onl y h a d a f e w stable pa ra mete rs, s o it ne e d ed fu rthe r testin g to be stable a t som e loca ti ons a nd a t di ff e r e nt t im e s

    Lateral strength Of urm piers: comparison between codified criteria and in-plane test results

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    The lateral resistance represents one of the most significant wall parameters to be used in the seismic analyses for the design/assessment of masonry buildings. In this article, an investigation on in-plane lateral strength of URM piers has been proposed thorough a comparison between the results from codified criteria and the outcomes of several experimental in-plane cyclic tests on masonry walls. In this context, a new database collecting the results of in-plane cyclic tests on unreinforced masonry piers, carried out within different research projects, has been devel-oped. The database consists of walls with bricks and blocks with different masonry materials (clay, lightweight aerated concrete, AAC, calcium silicate), bed-and head-joint typologies, di-mensions, boundary conditions, vertical applied loads and horizontal loading history. This source of information of consistent and reliable test results represents a necessary step into the process of definition of shared rules in the European context.Accepted Author ManuscriptApplied Mechanic

    Li–Yorke and distributionally chaotic operators

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    We study Li-Yorke chaos and distributional chaos for operators on Banach spaces. More precisely, we characterize Li-Yorke chaos in terms of the existence of irregular vectors. Sufficient "computable" criteria for distributional and Li-Yorke chaos are given, together with the existence of dense scrambled sets under some additional conditions. We also obtain certain spectral properties. Finally, we show that every infinite dimensional separable Banach space admits a distributionally chaotic operator which is also hypercyclic. © 2010 Elsevier Inc.The second author is supported in part by MEC and FEDER, Project MTM2008-05891. The third and fourth authors are supported in part by MEC and FEDER, Projects MTM2007-64222, MTM2010-14909 and by Generalitat Velenciana. Project PROMETEO/2008/101. We want to thank the referee for the suggestions.Bermúdez, T.; Bonilla, A.; Martínez Jiménez, F.; Peris Manguillot, A. (2011). Li–Yorke and distributionally chaotic operators. Journal of Mathematical Analysis and Applications. 373:83-93. https://doi.org/10.1016/j.jmaa.2010.06.011S839337

    Uj i S if at P r e b iotik S e r at P an gan T id ak L a r u t Air (ST L A) T e r e k str ak d ar i T e p u n g E m p u lu r P is an g Agun g d an P isan g M as

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    P isang mer upa ka n bua h subt ropis y a n g te rd a pa t ba n y a k di I ndon e sia. P roduk ti fitas pisang ter us mening ka t se c a r a fluktua ti f da ri tahun 2005 sa mpai 2010. P roduk si pisang y a n g ti ngg i men y e b a bka n pr oduk si e mpul ur pisang y a n g ti ngg i pula. Empul ur pisang mer upa ka n ba g i a n da ri pohon pisang y a n g ka ndun g a n utama n y a se ra t pa n ga n ti da k lar ut a ir (ST L A) . S e r a t pa n g a n ti da k lar ut a ir (ST L A) mer upa ka n komponen ka rbohidr a t y a ng ti da k da pa t di c e rn a oleh e nz im pe nc e rn a a n d a n subst ra t pe nti ng b a g i mi kr of lora kolon se hingg a be rpot e n si se ba g a i pr e biot ik. Untuk menja di pr e biot ik ba ha n pa n g a n h a rus taha n ter h a da p hidro li sis a sa m lambung a rtifi sial, da pa t mening ka tk a n surviv al b a kter i pr obiot ik da n se b a li kn y a d a pa t menur unk a n surviv al ba kter i pa to ge n. F e rm e ntasi spont a n e mpul ur pisan g mampu me n ing ka tkan pe ne rimaa n mut u se nsori s tepung e mpul ur pisan g y a n g dihaslk a n. I de nti fik a si ba kter i se lul oli ti k meng identifi ka si ba n y a k Bac il lus li c he nif ormis se ba ga i ba kter i y a n g be rpe r a n da l a m fe rme nt a si spont a n e mpul ur pis a ng . P e ne li ti a n ini be rtu juan untuk m e ng e kstra k S T L A da ri tep ung e mpul ur pisan g da n meng uji sifa t sif a t pre b iot ikn y a . P e ne li ti a n ter ba g i a tas be be ra p a taha p y a it u taha p pe rsia pa n pe n e li ti a n, pe mbuata n tepun g , e kstr a ksi S T L A da n uji sifa t sifa t pr e biot ik S T L A b e rda sa rka n ke taha na nn y a t e rha d a p hidroli sis a sa m la mbung a rtifisi a l, ke m a mpuann y a mening ka tk a n ke mamp ua n hidup ( surviv al ) ba kter i pr obiot ik L ac tobacill us ac idophi lus da n mene ka n ke mampua n hi dup ( surviv al ) ba kter i pa tog e n e nter opa to g e nik Es c he ric ia c oli ( EPEC ). Ekstra ksi S T L A men gg una k a n me tode pa da jurna l Eng l y st e t al. (1992 ) y a n g dim odifika si de ng a n men gg un a ka n g r a vim e tri (A OA C , 2000) . S e ra t p a nga n ti da k la rut a ir diuj i ke taha na nn y a ter h a d a p c a i ra n lambung m a nusi a de n ga n men gg una k a n meto de y a n g dig un a ka n da lam jurna l W iche inchot e t al . (2010 ). Uji surviv al pr obiot ik da n pa togen dil a kuka n de n g a n mengg un a ka n metode y a ng di g una ka n d a lam jurn a l Hue bne r e t al . (2007 ) da n jurna l B ur it i e t al . (2010 ). P rob iot ik y a n g di g una k a n a da lah L . ac idophi lus . B a kte ri pa to ge n y a n g di g un a ka n a d a lah b a kter i ente ropa to g e nik Es c he ricia c oli (E P EC). Ha sil pe ne li ti a n menunj ukka n ba hw a ka d a r S T L A e mpul ur pisan g a gung (f e rme nt a si 69,4% , kontr ol 67,7 % ) lebih ti ngg i di ba nding k a n S T L A e mpu lur pisang mas (f e rme ntasi 66,5 % , kontrol 62,6 % ). S e ra t p a ng a n ti da k lar ut a ir (ST LA) e mpul ur pisang taha n te rha da p h idroli sis a ntar a 98 99%, da pa t mensti mul a si pe rtumbuha n ba kter i pr obiot ik L . ac idophi lus da n da pa t men e ka n pe rtumbuha n b a kte ri pa togen. P e rla kua n fe rme nt a si t e r ke nda li pa d a e mpul ur pisa ng a g un g menin g ka tkan surviv al L. ac idophi ll us se be sa r 1,64% da n pa da e mpul ur pisang a g un g 0,36% . S e da ng k a n surviv al pa to g e n EPEC , S T L A e mpul ur pisa ng fe rme nt a si ter ke nd a li oleh B. li c he nif ormis menur unka n pe rtumbuha n EPEC p a da e mpul ur pisan g a g u ng se be s a r 7,63 % da n pa d a e mpul ur pisang m a s sebe s a r 6,4 % . P a da uji sifa t sifa t pr e bio ti k se mua S T L A sa mpel y a kni e mpul ur pisan g a gung kontrol (E AK ), e mpul ur pisang a g un g fe rme nt a si ter ke nda li (E AFT), e m pulur pisan g mas kontrol (E MK) , da n e mpul ur pisang ma s fe rme ntasi ter ke n da li (E MF T ) meme nuhi kr it e ria se ba ga i ka ndidat pr e biot ik. P e rla kua n f e rme ntasi ter k e nda li pa da e mpul ur pisan g menin g k a tkan sifa t sif a t pr e biot ik S T L A tepun g e mpul ur p isang y a n g dihasil ka n

    B E N T U K PE N GA W A S A N B E B A S V I S A K U N J U N G A N S I N G K A T ( B V K S ) O L E H K A N T O R K E I M I G R A S I A N K E P A D A W A R G A N E G A R A A S I N G Y A N G T I N G G A L D I I N D O N E S I A

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    e ne li ti a n y a n g be rjudul “ B E NTU K P EN GA W ASAN B E B AS V I S A KU NJ UN GA N S I NG K AT ( B VK S ) O L EH KA NTO R KE I M I G R AS I AN KEPAD A W ARGA N EGA R A AS I NG YA N G T I N GG A L D I I ND ON ES I A ” y a n g be rtujua n a nt a ra lain : P e r t a m a , m e n g a n a l i s a l e b i h l a n j u t t e n t a n g b e n t u k b e n t u k p e n g a w a s a n B e b a s Visa Kun ju ng a n S i ng k a t (B VK S ) , khu su sny a tenta ng ke lu a r m a su kny a or a ng a s i n g d i I n d o ne s i a. K e dua , untuk menge tahui lebih lanjut tenta ng a kibat hukum d a ri pe n y a l a h g una a n ij in B e b a s V i s a K u n j u n g a n S i n g k a t ( B V K S ) s e h i n g g a d a p a t d i k e t a h u i s a n k s i y a ng a k a n d i t e r a p k a n o l e h K a n t o r K e i m i g r a s i a n p e m e r i n ta h y a n g se s ua i d e ng a n p e r a t u r a n p e r u n da ng u nd a ng a n y a ng b e r l a k u . Untuk menc a pa i tuj ua n ter se but pe ne li ti men gg u na ka n metode pe n e li ti a n hukum pidana se c a ra y u ridis no rma ti f de n ga n taha pa n y a kni y a n g pe rta ma mela kuka n pe nde ka t a n masa lah se c a ra y ur idi s norma ti f ter ha da p da ta y a n g diper oleh, y a n g ke dua men gg un a ka n teknik pe ng umpul a n da t a , y a n g ke ti g a a na li sa ba ha n hukum d e n g a n m e tode kua li tatif . Ke sim pulan pe rta ma, B a hwa be ntuk pe nga wa s a n B e ba s Visa Kunj ung a n S i ng ka t (B VK S ) d i lak uka n mela lui dua h a l y a it u P e nga wa sa n L a p a n g a n da n pe nga wa s a n A d m i n i s t r a s i y a n g d i l a k u k a n d i t e m p a t t e m p a t p e m b e r i a n p e l a ya n a n k e i m i g r a s i a n , T e m p a t t e m p a t y a n g d im a k s u d , y a i t u : P e rw a ki lan R I ; Dire ktora t J e ndra l I mi gr a si; Ka ntor W il a y a h d e p a rte men k e ha kim a n d a n H a m ; Ka ntor ke im ig r a sian; T e m p a t p e m e r i k s a a n Im i g r a s i ( T P I) . Da n bi lama n a masa wa ktu y a n g dit e ntukan tela h ha bis oleh k a n t o r k e i m i g r a s i a n k e p a d a w a r g a a s i n g y a n g t i n g g a l d i w i l a y a h I n do n e si a , mak a ti nda ka n y a n g dib e rik a n ke pa d a wa r ga a sin g t e r s e bu t a d a l a h d e n g a n c a r a p e m u l a n g a n k e m b a l i k e n e ga r a a s a l o r a n g a s i n g ter se b ut . B a hwa pe n y a l a h g una a n ij in B e b a s Visa Kunjunga n S ing ka t (B VK S ) b a g i w a r ga ne ga ra a sing y a n g ti ng g a l d i I n d o n e s i a y a i tu m e m a n f a a t k a n s a r a n a k e r j a s e b a ga i k e d o k w i s a t a a t a u m e l e bih i b a t a s w a k t u y a n g dit e ntukan oleh ka ntor ke im igra si a n. Akiba t hukum d a n pe n y a lahg una a n B e b a s V i sa
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