Understanding of matrix embedding: a theoretical spectroscopic study of CO interacting with Ar clusters, surfaces and matrices

Through benchmark studies, we explore the performance of PBE density functional theory, with and without Grimme's dispersion correction (DFT-D3), in predicting spectroscopic properties for molecules interacting with rare gas matrices. Here, a periodic-dispersion corrected model of matrix embedding is used for the first time. We use PBE-D3 to determine the equilibrium structures and harmonic vibrational frequencies of carbon monoxide in interaction with small Ar clusters (CO–Arn, n = 1, 2, 3), with an Ar surface and embedded in an Ar matrix. Our results show a converging trend for both the vibrational frequencies and binding energies when going from the gas-phase to a fully periodic approach describing CO embedding in Ar. This trend is explained in terms of solvation effects, as CO is expected to alter the structure of the Ar matrix. Due to a competition between CO–Ar interactions and Ar–Ar interactions, perturbations caused by the presence of CO are found to extend over several Å in the matrix. Accordingly, it is mandatory to fully relax rare gas matrices when studying their interaction with embedded molecules. Moreover, we show that the binding energy per Ar is almost constant (∼−130 cm−1 atom−1) regardless of the environment of the CO molecule. Finally, we show that the concentration of the solute into the cold matrix influences the spectroscopic parameters of molecules embedded into cold matrices. We suggest hence that several cautions should be taken before comparing these parameters to gas phase measurements and to theoretical data of isolated species

Periodic dispersion-corrected approach for isolation spectroscopy of N2 in an argon environment: Clusters, surfaces, and matrices

© 2017 American Chemical Society. Ab initio and Perdew, Burke, and Ernzerhof (PBE) density functional theory with dispersion correction (PBE-D3) calculations are performed to study N 2 -Ar n (n ≤ 3) complexes and N 2 trapped in Ar matrix (i.e., N 2 @Ar). For cluster computations, we used both Møller-Plesset (MP2) and PBE-D3 methods. For N 2 @Ar, we used a periodic-dispersion corrected model for Ar matrix, which consists on a slab of four layers of Ar atoms. We determined the equilibrium structures and binding energies of N 2 interacting with these entities. We also deduced the N 2 vibrational frequency shifts caused by clustering or embedding compared to an isolated N 2 molecule. Upon complexation or embedding, the vibrational frequency of N 2 is slightly shifted, while its equilibrium distance remains unchanged. This is due to the weak interactions between N 2 and Ar within these compounds. Our calculations show the importance of inclusion of dispersion effects for the accurate description of geometrical and spectroscopic parameters of N 2 isolated, in interaction with Ar surfaces, or trapped in Ar matrices

A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari lambs

Citation: Mahjoubi, E., Amanlou, H., Yazdi, M. H., Aghaziarati, N., Noori, G. R., Vahl, C. I., . . . Baumgard, L. H. (2016). A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari lambs. Journal of Animal Science, 94(6), 2497-2505. doi:10.2527/jas2015-9697Thirty-two Afshari lambs were used in a completely randomized design with a 2 x 2 factorial arrangement of treatments to evaluate a nutritional supplement designed to provide multiple gluconeogenic precursors during heat stress (HS). Lambs were housed in thermal neutral (TN) conditions and fed ad libitum for 8 d to obtain covariate data (period 1 [P1]) for the subsequent experimental period (period 2 [P2]). During P2, which lasted 9 d, half of the lambs were subjected to HS and the other 16 lambs were maintained in TN conditions but pair fed (PFTN) to the HS lambs. Half of the lambs in each thermal regime were fed (top-dressed) 100 g/d of a feed supplement designed to provide gluconeogenic precursors (8 lambs in HS [heat stress with Glukosa {HSG}] and 8 lambs in PFTN [pair-fed thermal neutral with Glukosa]) and the other lambs in both thermal regimes were fed only the basal control diet (HS without Glukosa [HSC] and pair-fed thermal neutral without Glukosa). Heat stress decreased DMI (14%) and by design there were no differences between the thermal treatments, but HSG lambs had increased DMI (7.5%; P < 0.05) compared with the HSC lambs. Compared with PFTN lambs, rectal temperature and skin temperature at the rump, shoulder, and legs of HS lambs were increased (P < 0.05) at 0700 and 1400 h. Rectal temperature at 1400 h decreased for HSG lambs (0.15 +/- 0.03 degrees C; P < 0.05) compared with HSC lambs. Despite similar DMI between thermal treatments, ADG for HS and PFTN lambs in P2 was decreased 55 and 85%, respectively, compared with lambs in P1 (P < 0.01). Although the prefeeding glucose concentration was not affected by thermal treatment or diet, HSG lambs had increased postfeeding glucose concentration compared with HSC lambs (P < 0.05). In contrast to the glucose responses, circulating insulin was influenced only by thermal treatment; HS lambs had increased insulin concentration (P < 0.01) before feeding and decreased concentration (P < 0.05) after feeding compared with PFTN lambs. Heat-stressed lambs had decreased NEFA concentration before feeding (P < 0.01) but not after feeding relative to PFTN lambs. Although this nutritional strategy did not affect ADG, the lower rectal temperature in HSG lambs indicates that dietary inclusion of a mixture of glucogenic precursors can potentially benefit animal health during HS

Phytoplankton composition and abundance assessment in the Nador lagoon (Mediterranean coast of Morocco)

We evaluated phytoplankton abundance, composition and trophic state of the Nador lagoon (Morocco) on the basis of data taken in the period November 2007 to August 2008. Sampling was performed at 11 stations (bottle samples at 0.5 m depth and horizontal plankton net tows with mesh size of 20 mm). Among seven identified phytoplankton classes, diatoms and dinoflagellates dominated with 133 and 169 species, respectively. Frequent phytoplankton blooms were contributed by one to three species in the lagoon. Abundance and seasonality of phytoplankton characterized the Nador lagoon as a highly eutrophicated environment

Effects of Increasing Prepartum Dietary Protein Level Using Poultry by-Product Meal on Productive Performance and Health of Multiparous

The aim of this study was to compare the effects of two levels of crude protein using poultry by-product meals (PBPM) fed during late gestation on the performance, blood metabolites, and colostrum composition of Holstein dairy cows. Sixteen multiparous cows 26±6 d before expected calving were assigned randomly to two treatments containing 1) 14% and 2) 16% crude protein. The cow’s BCS was 3.56 ± 0.5 on average, at the beginning of the trial. Yields of milk, protein, lactose, fat, and SNF were not affected by prepartum dietary CP level. Colostrum composition (fat, CP and Total solids), blood metabolites (Ca, Glucose, Total protein, Albumin, Globulin and Urea N), and metabolic diseases incidence were not influenced by prepartum dietary CP level. There was no significant difference between treatments in body weight and BCS changes. As expected, blood urea N before calving was higher in the cows fed 16% CP diets. Serum cholesterol during prepartum and postpartum periods was significantly decreased as the CP increased in the diet. In general, although postpartum glucose level increased in cows which received 16% CP in the diet, it seems that no other obvious advantages over feeding the 14% CP diet are apparent. So feeding this last diet is recommended to close up cows

The Effect of Using Rumen Protected Methionine (Mepron) on Production and Reproduction Performance of Holstein Lactating Cows during Early Lactation under Field Condition

In order to examine the effect of using rumen protected methionine (Mepron, Evonik Industries, Hanau, Germany) on productive and reproductive performance under field condition, 195 Holstein cows were used in a unbalanced completely randomized design and 2 groups. Experimental treatments consisted of: 1) control group with 110 Holstein dairy cows (71±51 DIM and 47.5±12 milk yield) and without Mepron and 2) experimental group with 85 Holstein dairy cows (85±59 DIM and 47.0±12 milk yield) and 13 g Mepron per cow/d. Cows were group fed with TMR and 4 times a day. The diets were balanced with AminoCow® software. Using Mepron decreased CP content from 17.05% in control group to 16.47% in experimental group, while other nutrients were similar between two diets. Adding Mepron to diet resulted in a significant increase in dry matter intake (

A randomized field trial assessing the timing of postpartum calcium bolus administration on milk yield of multiparous Holstein cows

ABSTRACT: Recent studies have shown that cows with subclinical hypocalcemia (SCH) at 4 d in milk (DIM), regardless of their blood Ca concentration before that time point, suffer from an increased early-lactation disease risk and reduced milk yield, whereas cows experiencing a transient reduction in blood Ca that regain normocalcemia by 4 DIM are at a reduced risk of disease and have greater milk yields. With a goal of improving outcomes for dyscalcemic cows with SCH at 4 DIM, our primary objective was to assess the effect of a herd-level oral Ca bolus strategy that delayed supplementation to 24 and 48 h postpartum on productive performance of multiparous Holstein cows. Our secondary objectives were to assess the effects of delayed Ca bolus supplementation on blood Ca concentration, disease incidence within 30 DIM, and pregnancy risk to first service. At calving, multiparous cows on a single commercial dairy farm in Iran were randomly assigned to 1 of 3 treatment groups: (1) control, no Ca bolus administration (CON; n = 95); (2) traditional bolus, one Ca bolus administered immediately following calving and a second Ca bolus administered 24 h after calving (TRD, n = 102); or (3) experimental bolus, one Ca bolus administered 24 h after calving with a second Ca bolus administered 48 h after calving (EXP, n = 99). Blood samples were collected at 0, 24, 48, 72, and 96 h, and 7 d after parturition, with sampling occurring before bolus administration for the TRD (0 and 24 h) and EXP (24 and 48 h) groups. A general linear mixed model was created to analyze the change milk yield over the first 4 monthly tests and serum Ca concentrations over 7 DIM. Given the lack of disease events diagnosed within 30 DIM, no statistical analysis was conducted for this outcome. The effect of treatment group on risk of pregnancy to first service was assessed using Poisson regression. The incidence of dyscalcemia within CON cows was 72%. We found no difference in mean monthly milk yield among treatment groups across the first 4 tests, with an average monthly production of 51.8 ± 8.8 kg/d for CON cows, 52.5 ± 8.7 kg/d for TRD cows, and 51.8 ± 8.7 kg/d for EXP cows. Mean blood Ca concentration also did not differ across 7 DIM among treatment groups and was 2.04 mmol/L [95% confidence interval (CI) = 2.00 to 2.07 mmol/L] for CON cows, 2.06 mmol/L (95% CI = 2.03 to 2.09 mmol/L) for TRD cows, and 2.09 mmol/L (95% CI = 2.05 to 2.12 mmol/L) for EXP cows. The risk of pregnancy to first service was numerically greater for CON than TRD and EXP cows but not statistically different; however, our study was underpowered for this outcome. Under the conditions of our study, our findings suggest that delaying oral Ca bolus supplementation to 24 and 48 h postpartum has no effect on milk production across the first 4 monthly tests

Insights into the use of phenylalanine ammonia-lyase as a marker for the selection of olive cultivars with improved virgin olive oil functionality

Virgin olive oil (VOO) represents the main source of lipids in the Mediterranean diet, its phenolic fraction being one of the main contributors to the health-promoting properties of this diet. Phenolic composition of VOO is directly related to the content of phenolic glycosides present in the olive fruit, which undergo a series of modifications during the oil extraction process. The vast majority of these phenolic glycosides comprise phenylethanoid derivatives of tyrosol and hydroxytyrosol whose metabolic origin are the hydroxylated aromatic amino acids 4-hydroxyphenylalanine (tyrosine) and 3,4-dihydroxyphenylalanine (L-DOPA). However, the synthesis of phenolic compounds in plants has traditionally been linked to the action of the phenylalanine ammonia-lyase (PAL) enzymes on the non-hydroxylated aromatic amino acid phenylalanine, thus constituting the first step in the biosynthetic pathway of different families of phenolic compounds known as phenylpropanoids. In this research, the implication of PAL in the conformation of the phenolic profile of olive fruit and VOO has been studied through the combined analysis of phenolic composition, PAL activity and gene expression in the mesocarp of the fruit from olive cultivars whose oils have very contrasting phenolic contents. According to the data, the role of PAL would be restricted to the most advanced stages of the fruit ripening process, controlling the channeling of phenylalanine towards the synthesis of phenylpropanoids, mainly anthocyanins, and thus reducing the metabolisation of tyrosine and L-DOPA towards the synthesis of phenylethanoids. Consequently, it is advisable not to use the selection of olive cultivars based on molecular markers related to PAL genes in olive breeding programs aimed at obtaining cultivars that give rise to oils with improved functional properties.Peer reviewe