Diamond for Fiber-Optic Raman Spectroscopy

Raman spectroscopy is a powerful technique for molecular structural studies and concentration measurement. Being a single beam technique, the Raman intensity depends on the optical power of the excitation source, optical alignment of the system, detector response as well as species concentration. To eliminate the unwanted variations in the system and get the concentration information of the species, intensity referencing is necessary. The existing referencing methods either use a constant Raman band of the sample, or add a chemically inert material with known concentration into the sample. Unfortunately, the former method is not always applicable and the latter is not acceptable for in situ process monitoring. A new concept of using diamond as an intensity standard in quantitative Raman analysis is presented in this dissertation. Combined with fiber optics, a self-referenced universal Raman probe is developed. Performances of five probe designs are investigated. Results indicate that diamond-referenced probes are insensitive to the excitation power fluctuation and optical alignment. Chemical vapor deposited (CVD) diamond film is investigated as an alternative to the expensive bulk diamond. The CVD diamond referenced probe shows performance similar to the bulk diamond probe. A remote measurement is also performed with a 500-foot fiber probe, which shows the potential of long distance in situ concentration monitoring in an industrial environment

Cross-fiber Bragg grating transducer

A transducer has been invented that uses specially-oriented gratings in waveguide a manner that allows the simultaneous measurement of physical phenomena (such as shear force, strain and temperature) in a single sensing element. The invention has a highly sensitive, linear response and also has directional sensitivity with regard to strain. The transducer has a waveguide with a longitudinal axis as well as two Bragg gratings. The transducer has a first Bragg grating associated with the waveguide that has an angular orientation .theta..sub.a relative to a perpendicular to the longitudinal axis such that 0.degree.<.theta..sub.a <.theta..sub.max. The second Bragg grating is associated with the waveguide in such a way that the angular orientation .theta..sub.b of the grating relative to a perpendicular to the longitudinal axis is (360.degree.-.theta..sub.max)<.theta..sub.b <360.degree.. The first Bragg grating can have a periodicity .LAMBDA..sub.a and the second Bragg grating can have a periodicity .LAMBDA..sub.b such that the periodicity .LAMBDA..sub.a of the first Bragg grating does not equal the periodicity .LAMBDA..sub.b of the second Bragg grating. The angle of the gratings can be such that .theta..sub.a =360.degree.-.theta..sub.b. The waveguide can assume a variety of configurations, including an optical fiber, a rectangular waveguide and a planar waveguide. The waveguide can be fabricated of a variety of materials, including silica and polymer material

Microwave Plasma Chemical Vapor Deposited Diamond Tips for Scanning Tunneling Microscopy

Diamond microparticles were grown on etched tungsten wires using a microwave plasma-assisted chemical vapor deposition process. The apexes on cubo-octahedral particles bound by {100} and {111} facets were effectively used as tunneling tips for scanning tunneling microscopy. The atomically resolved surface image of highly oriented pyrolytic graphite was acquired. Tunneling characteristics revealed a higher electron emission from the diamond tips than that from the platinum–iridium tips. The same diamond tips were used to produce surface indentation and its image. © 1997 American Institute of Physics

Chemical Vapor Deposited Diamond Films for Self-Referencing Fiber Optic Raman Probes

Diamond thin films grown by the microwave plasma enhances chemical vapor deposition (CVD) process have been investigated as an internal reference in fiber optic remote Raman sensing. The growth parameters have been optimized for diamond thin films on quarts substrates using a gas mixture of methane, carbon dioxide, and hydrogen. The resulting films exhibit essentially no Raman spectral background while exhibiting a strong Raman peak at 1332 cm-¹. The films are used as an internal reference in the quantitative measurement of chemical concentration using remote fiber optic Raman sensing. Internal referencing is accomplished by normalizing all spectral intensities of the chemical species to the integrated area of the CVD diamond reference peak at 1332 cm-¹ and verified using ethanol/water solutions. It is shown that the measurement is independent of laser power fluctuations

Novi VP2/VP3 rekombinantni senekavirus A izoliran u sjevernoj Kini

Senecavirus A (SVA), previously called the Seneca Valley virus, is the only member of the genus Senecavirus within the family Picornaviridae. This virus was discovered as a serendipitous finding in 2002 and named Seneca Valley virus 001 (SVV-001). SVA is an emerging pathogen that can cause vesicular lesions and epidemic transient neonatal a sharp decline in swine. In this study, an SVA strain was isolated from a pig herd in Shandong Province in China and identified as SVA-CH-SDFX-2022. The full-length genome was 7282 nucleotides (nt) in length and contained a single open reading frame (ORF), excluding the poly (A) tails of the SVA isolates. Phylogenetic analysis showed that the isolate shares its genomic organization, resembling and sharing high nucleotide identities of 90.5% to 99.6%, with other previously reported SVA isolates. The strain was proved by in vitro characterization and the results demonstrate that the virus has robust growth ability in vitro. The recombination event of the SVA-CH-SDFX-2022 isolate was found and occurred between nts 1836 and 2710, which included the region of the VP2 (partial), and VP3 (partial) genes. It shows the importance of faster vaccine development and a better understanding of virus infection and spread because of increased infection rates and huge economic losses. This novel incursion has substantial implications for the regional control of vesicular transboundary diseases, and will be available for further study of the epidemiology of porcine SVA. Our findings provide useful data for studying SVA in pigs.Senekavirus A (SVA), prije nazivan virusom doline Seneca Valley, jedini je pripadnik roda senekavirusa u porodici Picornaviridae. Virus je slučajno otkriven 2002. i nazvan virusom doline Seneca 001 (SVV-001). SVA je novi patogen koji može uzrokovati vezikularne lezije i prolaznu epidemiju novorođene prasadi s naglim gubicima u proizvodnji. U ovom je istraživanju soj SVA izoliran u populaciji svinja iz provincije Shandong u Kini i identificiran kao SVA-CHSDFX-2022. Kompletni genom izolata SVA imao je 7282 nukleotida (nt) u dužini i sadržavao je jedan otvoreni okvir za očitavanje (ORF), bez poli-A repova. Filogenetska je analiza pokazala da izolat u velikoj mjeri sadržava genomsku organizaciju i nukleotidne identitete, od 90,5 % do 99,6 %, s drugim poznatim SVA izolatima. Karakterizacija virusa je pokazala da ima veliku sposobnost rasta in vitro. Pronađena je rekombinacija izolata SVA-CH-SDFX-između nukleotida 1836 i 2710 što je uključilo regiju gena VP2 (parcijalno) i gena VP3 (parcijalno). Zbog visoke stope infektivnosti i golemih ekonomskih gubitaka važan je brži razvoj cjepiva i bolje razumijevanje zaraze. Rezultati ovog istraživanja pružaju korisne podatke za proučavanje SVA virusa, posebno s obzirom na njegovu epidemiologiju u svinja i regionalnu prekograničnu kontrolu vezikularnih bolesti

Analiza genskih varijacija rekombinantnog soja dobivenog iz triju linija virusa-2 reproduktivnog i respiratornog sindroma svinja

Since the rise of the porcine reproductive and respiratory syndrome virus (PRRSV) in China, gene mutations have frequently occurred. To understand the current prevalence and evolution of PRRSV in Shandong Province, 1,528 samples suspected of PRRSV were collected from local pig farms of different sizes. The complete genome sequence of the PRRSV strain SDLY-27 was determined by next-generation sequencing (NGS) technology. The genomic sequence of SDLY-27 was 15,363 nucleotides (nt) in length, comparative analysis of the whole genome sequence suggested that the homology between SDLY 27 and 81 PRRSV strains from China and other countries in genbank was 61.9 ~ 96.4%. This study is the first to detect recombinants from multiple recombination events among the Lineage 8 (JXA1-like strains), Lineage 5 (RespPRRSV-MLV and VR2332 strains) and Sublineage 1.5 (NADC34-like strains) in Shandong, China, and provides new data for the epidemiological study of PRRSV in China. This study enriches the epidemiological data on PRRSV in Shandong Province, China. It provides an important reference for the development of new vaccines and for the prevention and control of PRRSV in China.Usporedno sa širenjem virusa reproduktivnog i respiratornog sindroma svinja (PRRSV) u Kini, sve su češće bile i njegove genske mutacije. Kako bi se ustanovila trenutačna prevalencija i evolucija PRRSV-a u pokrajini Shandong, s lokalnih farmi prikupljeno je 1528 uzoraka svinja različitih kategorija za koje je postojala sumnja na zarazu PRRSVom. Kompletan genomski slijed soja SDLY-27 PRRSV-a određen je tehnologijom sekvenciranja sljedeće generacije (NGS). Slijed je imao dužinu od 15 363 nukleotida (nt), a komparativna analiza cijeloga genomskog slijeda uputila je na to da je homolognost između sojeva SDLY 27 i 81 PRRSV-a iz Kine i uzoraka u banci gena iz drugih zemalja 61,9~96,4%. Ovo je prvo istraživanje koje je otkrilo rekombinantne sojeve iz višestrukih rekombinacija među linijama 8 (sojevi nalik na JXA1), 5 (sojevi RespPRRSV-MLV i VR2332) i podlinije 1,5 (sojevi nalik na NADC34) u Shandongu, Kina.Kao takvo, istraživanje pruža nove podatke o epidemiologiji PRRSV-a u Kini, posebno u pokrajini Shandong, a ujedno predstavlja i važnu referenciju za razvoj novih cjepiva te prevenciju i kontrolu bolesti uzrokovane navedenim virusom

Highly Stable and Conductive Microcapsules for Enhancement of Joule Heating Performance

Nanocarbons show great promise for establishing the next generation of Joule heating systems, but suffer from the limited maximum temperature due to precociously convective heat dissipation from electrothermal system to surrounding environment. Here we introduce a strategy to eliminate such convective heat transfer by inserting highly stable and conductive microcapsules into the electrothermal structures. The microcapsule is composed of encapsulated long-chain alkanes and graphene oxide/carbon nanotube hybrids as core and shell material, respectively. Multiform carbon nanotubes in the microspheres stabilize the capsule shell to resist volume-change-induced rupture during repeated heating/cooling process, and meanwhile enhance the thermal conductance of encapsulated alkanes which facilitates an expeditious heat exchange. The resulting microcapsules can be homogeneously incorporated in the nanocarbon-based electrothermal structures. At a dopant of 5%, the working temperature can be enhanced by 30% even at a low voltage and moderate temperature, which indicates a great value in daily household applications. Therefore, the stable and conductive microcapsule may serve as a versatile and valuable dopant for varieties of heat generation systems