Impact of veterinary assistance on the health of working horses in Nicaragua

Working horses in developing countries are mostly used for transportation. They are often owned by people with limited economical resources and lack of knowledge about how to take care of the horses and due to this the horses often suffer from problems such as dehydration, poor body condition, lesions and parasitic infections. The aim of this master thesis was to investigate if free veterinary care improved the health and hydration status of working horses in Nicaragua and it was performed as a part of a project called “Free veterinary assistance for working horses and training of their owners as veterinary promoters in the Pacific coast of Nicaragua”. Five parameters were used to investigate whether free care improved the health of working horses in six towns along the Pacific Coast of Nicaragua. The parameters used were body condition, dehydration, hematocrit, plasma protein and parasite eggs per gram of faeces (EPG). The towns were visited three times at monthly intervals. For the purpose of the visits, a mobile clinic was set up and working horses were examined. A total of 441 horses were examined; of these 47 were attended all three times, 130 were attended twice and 311 only once. Body condition and dehydration of the horses were scored subjectively using scales of 1-5 and 0-10 respectively. For dehydration a skin tent test was used. Blood and faecal samples were collected and thereafter analyzed at the University of Commercial Sciences (UCC) in Managua. Of all examined horses 44% were classified as thin or very thin and 41% were dehydrated. At the first examination of the horses the mean hematocrit value was 23 ± 2%, the plasma protein 72 ± 2 g/l and the EPG 782 ± 393. Of the five parameters only the plasma protein showed a significant decrease over the study period which could indicate for an improved hydration status

The way to panchromatic copper(I)-based dye-sensitized solar cells: co-sensitization with the organic dye SQ2

We report the first example of n-type dye-sensitized solar cells (DSCs) co-sensitized with a copper(I)-based sensitizer and an organic dye. The heteroleptic copper(I) dye [Cu( 3 )( 1 )] + ( 3 = anchoring ligand ((6,6'-dimethyl-[2,2'-bipyridine]-4,4'-diyl)bis(4,1-phenylene))bis(phosphonic acid), 1 = ancillary ligand 2-(6-methylpyridin-2-yl)thiazole) was combined with the commercially available squaraine derivative SQ2 . By prudent matching of the external quantum efficiency (EQE) maxima arising from the two dyes in complementary parts of the visible spectrum, we have achieved the highest photoconversion efficiency reported for a copper-based DSC (65.6% relative to N719 set at 100%). This confirms the potential for the use of Earth-sustainable copper as the basis of sensitizers in DSCs. A combination of J–V measurements ( J = current density, V = voltage), EQE spectra and electrochemical impedance spectroscopy has been used to optimize and understand the effective use of the co-sensitized DSCs. We have shown that the sequences in which the photoanodes of the n-type DSCs are exposed to [Cu( 3 )( 1 )] + and SQ2 , and the times that the electrodes are immersed in the respective dye baths, critically influence the overall performance of the DSCs. A degree of aggregation of the SQ2 molecules on the electrode surface is important in terms of achieving panchromatic light-harvesting of the co-sensitized DSCs, but excessive aggregation is detrimenta

Optimization of performance and long-term stability of p-type dye-sensitized solar cells with a cycloruthenated dye through electrolyte solvent tuning

p-Type dye sensitized solar cells (DSCs) have been assembled using the structurally unrefined, zwitterionic cyclometallated ruthenium dye [Ru(bpy) 2 (H 1 )] (H 3 1 = (4-(2-phenylpyridin-4-yl)phenyl)phosphonic acid) in combination with FTO/NiO photocathodes and an I 3 – /I – /acetonitrile (AN) electrolyte. Values of the short-circuit current density ( J SC ) = 4.06 mA cm –2 , open-circuit voltage ( V OC ) = 95 mV and photoconversion efficiency ( η ) = 0.139% are the highest achieved for state-of-the-art cyclometallated ruthenium dyes in p-type DSCs; data are confirmed using duplicate devices. J SC values are higher than those observed for the standard dye P1, and electrochemical impedance spectroscopy (EIS) shows that DSCs with [Ru(bpy) 2 (H 1 )] exhibit a both a lower transport resistance ( R t ) and recombination resistance ( R rec ) than DSCs with P1. Changing the electrolyte solvent from AN to propionitrile (PN), valeronitrile (VN), 3-methoxypropionitrile (MPN) or N -methylpyrrolidone (NMP) confirms a dependence of J SC on solvent in the order AN > PN > MPN > VN > NMP, whilst V OC follows the trend VN > PN > MPN > AN > NMP. The opposing trends in J SC and V OC lead to only a small drop in the overall η values for PN versus AN. EIS measurements revealed that although PN has a higher resistance to recombination reactions than AN, it also exhibits an increased amount of trapped charge carriers, leading to worsened DSC performance. DSCs based on AN do not remain stable over a 1-2 month period; both J SC and V OC decrease significantly. However, DSCs with the less volatile and more viscous PN show enhanced performance upon ageing with a gain in J SC over the first 33 days. Electrolytes with mixed solvents were investigated; addition of PN, VN or MPN to AN leads to lower J SC and this is most pronounced for VN and least marked for PN. The optimal solvent is an AN:PN mixture with volume ratios of 3:1 or 1:1; this mixed solvent results in enhanced long-term stability with respect to DSCs with pure AN and this is at the expense of a only small decrease in photoconversion efficienc

Cyanoacrylic- and (1-cyanovinyl)phosphonic acid anchoring ligands for application in copper-based dye-sensitized solar cells

The syntheses and characterization of four new anchoring ligands (2–5) for copper(I) bis(diimine) dyes in dye-sensitized solar cells (DSCs) are reported. Ligands 2 and 3 contain a 6,6′-dimethyl-2,2′-bipyridine copper-binding unit, while 4 and 5 contain a 2,9-dimethyl-1,10-phenanthroline unit; 2 and 4 contain cyanoacrylic acid anchoring units, and 3 and 5 possess (1-cyanovinyl)phosphonic acid anchors. The performance of DSCs sensitized by [Cu(Lanchor)(Lancillary)]+ in which Lanchor is 2–5 and Lancillary is either 6,6′-dimethyl-2,2′-bipyridine (6) or 6-trifluoromethyl-2,2′-bipyridine (7) are compared with those of DSCs containing the dyes [Cu(1)(6)]+ or [Cu(1)(7)]+ where anchoring ligand 1 is the previously reported and well-performing ((6,6′-dimethyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid). Among dyes incorporating 2–5, the best performing dye contained anchor 3 (6,6′-Me2bpy/(1-cyanovinyl)phosphonic acid combination). The better performances of dyes containing the bpy-based 2 and 3 compared to the phen-based 4 and 5 are rationalized largely in terms of the greater flexibility of the bpy vs. phen unit, allowing dyes containing 2 and 3 to adopt a conformation that leads to better surface coverage on mesoporous TiO2. Replacing 1 by 3 leads to a small gain in the short-circuit current density (JSC), but dyes with anchor 1 (in place of 3) have enhanced open-circuit voltage (VOC). The results of electrochemical impedance spectroscopy (EIS) support the trends found from the J–V measurements. The EIS data for DSCs with dyes containing anchors 3 or 1 are compared; the latter has a higher recombination resistance and chemical capacitance although the former exhibits a lower transport resistance

Copper-based Dye-sensitized Solar Cells with Quasi-Solid Nano Cellulose Composite Electrolytes

The study presented describes the preparation of solvent-free nano composite gel electrolytes in combination with  copper(I)-based dye-sensitized solar cells (DSSCs). The electrolytes comprise poly(ethylene oxide) (PEO) and cellulose nano crystals (CNCs) and an I 3 – /I – redox shuttle. The quasi-solid-state DSSCs show increased photoconversion performance with increased amount of CNC in the electrolyte. DSSC performances measured on the day that the devices are fabricated show that when the electrolyte is composed of 80% CNC, a cell efficiency of 1.09% is reached compared to 1.16% using a standard liquid I 3 – /I – electrolyte. DSSCs containing the nano composites and the copper(I)-based dye show robust stability over time, and after 60 days, DSSCs with the PEO/CNC/I 3 – /I – electrolyte outperform those containing the liquid electrolyt

Exploring simple ancillary ligands in copper-based dye-sensitized solar cells: effects of a heteroatom switch and of co-sensitization

The copper( I ) complexes [Cu(1) 2 ][PF 6 ], [Cu(2) 2 ][PF 6 ], [Cu(3) 2 ][PF 6 ] and [Cu(4) 2 ][PF 6 ] (1 . 2-(1H-imidazol-2-yl)- 6-methylpyridine, 2 . 2-(6-methylpyridin-2-yl)oxazole, 3 . 2-(6-methylpyridin-2-yl)thiazole and 4 . 2- methyl-6-(1-methyl-1H-imidazol-2-yl)pyridine) are reported. The crystal structures of [Cu(2) 2 ][PF 6 ]$ 0.5CH 2 Cl 2 and [Cu(3) 2 ][PF 6 ] confirm N,N 0 -chelation modes for 2 and 3, and tetrahedral copper( I ). In the solution absorption spectra, the MLCT band shifts to lower energy with a change in heteroatom (O, 424 nm; NH, 435 nm; NMe, 446 nm; S, 465 nm). [Cu(1) 2 ][PF 6 ] and [Cu(4) 2 ][PF 6 ] undergo copper-centred oxidative processes at lower potential than the complexes with O or S heteroatoms. Heteroleptic complexes [Cu(5)(L)] + (5 . ((6,6 0 -dimethyl-[2,2 0 -bipyridine]-4,4 0 -diyl)bis(4,1-phenylene)bis(phosphonic acid)), L . 1–4) were assembled on FTO/TiO 2 electrodes. The shift in the MLCT band (O NH < NMe < S) in the solid-state absorption spectra of the dye-functionalized electrodes parallels that of solution. The photoconversion efficiencies (h) of masked, dye-sensitized solar cells (DSCs) containing [Cu(5)(L)] + (L . 1– 4) dyes and an I/I 3 redox shuttle follow the order [Cu(5)(1)] + (3.03%) > [Cu(5)(3)] + (2.88%) > [Cu(5)(4)] + (2.71%) > [Cu(5)(2)] + (2.62%) relative to 7.55% for N719. Ancillary ligand 1 (with NH) leads to the highest open-circuit voltage (V OC . 608 mV) whilst 3 (S-heteroatom) gives the highest short-circuit current density (J SC . 7.76 mA cm 2 ). The performances of [Cu(5)(1)] + and [Cu(5)(3)] + are understood with the aid of electrochemical impedance spectroscopy (EIS). The DSC with [Cu(5)(1)] + exhibits a high chemical capacitance (C m ) and a low recombination resistance (R rec ); since the latter is offset by a low transport resistance (R tr ), a high J SC and V OC are observed for [Cu(5)(1)] + . DSCs with [Cu(5)(3)] + have the lowest R tr of all four devices. The performance of DSCs sensitized by a combination of [Cu(5)(1)] + and [Cu(5)(3)] + were assessed in order to capitalize upon the high V OC of [Cu(5)(1)] + and the high J SC of [Cu(5)(3)] + . After FTO/ TiO 2 functionalization with anchor 5, the electrodes were treated with a 1 : 1 mix of [Cu(5)(1)] + and [Cu(5)(3)] + or sequentially with [Cu(5)(3)] + then [Cu(5)(1)] + , or [Cu(5)(1)] + then [Cu(5)(3)] + . The DSC performances and the EIS parameters are consistent with competition between 1 and 3 for surface binding-sites; 1 dominates over 3, both in binding and in contribution to the overall photoresponse

Understanding why replacing I3–/I– by cobalt(II)/(III) electrolytes in bis(diimine)copper(I)-based dye-sensitized solar cells improves performance

The performances of dye-sensitized solar cells (DSCs) comprising heteroleptic bis(diimine)copper( I ) based dyes combined with either [Co(bpy) 3 ] 2+/3+ , [Co(phen) 3 ] 2+/3+ or I 3 /I redox mediators (bpy 1/4 2,2 0 - bipyridine, phen 1/4 1,10-phenanthroline) have been evaluated. The copper( I ) dyes contain the anchoring ligand ((6,6 0 -dimethyl-[2,2 0 -bipyridine]-4,4 0 -diyl)bis(4,1-phenylene))bis(phosphonic acid), 1, and an ancillary ligand (2, 3 or 4) with a 2,9-dimethyl-1,10-phenanthroline metal-binding domain. Ligands 2 and 3 include imidazole 2 0 -functionalities with 4-(diphenylamino)phenyl (2) or 4-(bis(4-n-butoxy) phenylamino)phenyl (3) domains; in 4, the phen unit is substituted in the 4,7-positions with holetransporting 4-(diphenylamino)phenyl groups. The photoconversion efficiency, h, of each of [Cu(1)(2)] + , [Cu(1)(3)] + and [Cu(1)(4)] + considerably improves by replacing the I 3 /I electrolyte by [Co(bpy) 3 ] 2+/3+ or [Co(phen) 3 ] 2+/3+ , and after a change of electrolyte solvent (MeCN to 3-methoxypropionitrile). Due to the faster charge transfer kinetics and more positive redox potential, the cobalt-based electrolytes are superior to the I 3 /I electrolyte in terms of open-circuit voltage (V OC ), short-circuit current (J SC ) and h; values of V OC 1/4 594 mV, J SC 1/4 9.58 mA cm 2 and h 1/4 3.69% (relative to h 1/4 7.12% for N719) are achieved for the best performing DSC which contains [Cu(1)(4)] + and [Co(bpy) 3 ] 2+/3+ . Corresponding values for [Cu(1)(4)] + and I 3 /I DSCs are 570–580 mV, 5.98–6.37 mA cm 2 and 2.43–2.62%. Electrochemical impedance spectroscopy (EIS) has been used to study DSCs with [Cu(1)(4)] + and the three electrolytes. EIS shows that the DSC with I 3 /I has the highest recombination resistance, whereas the [Co(phen) 3 ] 2+/3+ electrolyte gives the highest chemical capacitance and V OC and, between [Co(bpy) 3 ] 2+/3+ and [Co(phen) 3 ] 2+/3+ , the higher recombination resistance. The [Co(phen) 3 ] 2+/3+ electrolyte exhibits the highest mass transport restrictions which result in a lower J SC and DSC efficiency compared to the [Co(bpy) 3 ] 2+/3+ electrolyte

Modular synthesis of simple cycloruthenated complexes with state-of-the-art performance in p-type DSCs

A modular approach based on Suzuki-Miyaura cross coupling and Miyaura borylation has been used to prepare two cyclometallated [Ru(N^N) 2 (C^N)] + complexes which possess either a carboxylic or phosphonic acid group attached via a phenylene spacer to the 4-position of the pyridine ring in the C^N ligand. The key intermediate in the synthetic pathway is [Ru(bpy) 2 ( 1 )] + where bpy = 2,2'-bipyridine and H 1 is 4-chloro-2-phenylpyridine. The crystal structure of [Ru(bpy) 2 ( 1 )][PF 6 ] is presented. Reaction of [Ru(bpy) 2 ( 1 )][PF 6 ] with 4-carboxyphenylboronic acid leads to [Ru(bpy) 2 (H 6 )][PF 6 ], while the phosphonic acid analogue is isolated as the zwitterion [Ru(bpy) 2 (H 5 )]. The cyclometallated complexes have been characterized by mass spectrometry, multinuclear NMR spectroscopy, absorption spectroscopy and electrochemistry. [Ru(bpy) 2 ( 5 )] adsorbs onto NiO FTO/NiO electrodes (confirmed by solid-state absorption spectroscopy) and its performance in p-type dye-sensitized solar cells (DSCs) has been compared to that of the standard dye P1; two-screen printed layers of NiO give better DSC performances than one layer. Duplicate DSCs containing [Ru(bpy) 2 (H 5 )] achieve short-circuit current densities ( J SC ) of 3.38 and 3.34 mA cm –2 and photoconversion efficiencies ( η ) of 0.116 and 0.109%, respectively, compared to values of J SC = 1.84 and 1.96 mA cm –2 and η = 0.057 and 0.051% for P1. Despite its simple dye structure, the performance of [Ru(bpy) 2 (H 5 )] parallels the best-performing cyclometallated ruthenium(II) dye in p-type DSCs reported previously (He et al , J. Phys. Chem. C , 2014, 118 , 16518) and confirms the effectiveness of a phosphonic acid anchor in the dye and the attachment of the anchoring unit to the pyridine (rather than phenyl) ring of the cyclometallating ligan

Multiple spillovers from humans and onward transmission of SARS-CoV-2 in white-tailed deer.

Many animal species are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and could act as reservoirs; however, transmission in free-living animals has not been documented. White-tailed deer, the predominant cervid in North America, are susceptible to SARS-CoV-2 infection, and experimentally infected fawns can transmit the virus. To test the hypothesis that SARS-CoV-2 is circulating in deer, 283 retropharyngeal lymph node (RPLN) samples collected from 151 free-living and 132 captive deer in Iowa from April 2020 through January of 2021 were assayed for the presence of SARS-CoV-2 RNA. Ninety-four of the 283 (33.2%) deer samples were positive for SARS-CoV-2 RNA as assessed by RT-PCR. Notably, following the November 2020 peak of human cases in Iowa, and coinciding with the onset of winter and the peak deer hunting season, SARS-CoV-2 RNA was detected in 80 of 97 (82.5%) RPLN samples collected over a 7-wk period. Whole genome sequencing of all 94 positive RPLN samples identified 12 SARS-CoV-2 lineages, with B.1.2 (n = 51; 54.5%) and B.1.311 (n = 19; 20%) accounting for ∼75% of all samples. The geographic distribution and nesting of clusters of deer and human lineages strongly suggest multiple human-to-deer transmission events followed by subsequent deer-to-deer spread. These discoveries have important implications for the long-term persistence of the SARS-CoV-2 pandemic. Our findings highlight an urgent need for a robust and proactive "One Health" approach to obtain enhanced understanding of the ecology, molecular evolution, and dissemination of SARS-CoV-2