Urea Inclusion Research Articles

Insulated Polyacetylene Chains in an Inclusion Complex by Photopolymerization

ABSTRACTThe properties of a material often depend on the degree of order of their atomic, molecular, or crystalline domain components. This is expected to be especially true for the case of polyacetylene, whose properties are highly anisotropic. For many applications, it may be necessary to have macroscopic order but not necessarily crystalline order. Having polyacetyelene chains fully extended and aligned parallel to each other may be sufficient for these applications even without order of the chains around their long axis. We report here progress in the use of an inclusion crystal containing a photo-reactive precursor to prepare high molecular weight polyacetylene. Raman spectroscopy was performed to probe the resulting conjugated polyene chains. Ultraviolet irradiation of a 1,4-diiodo-1,3-butadiene/urea inclusion complex results in the appearance of new resonance-enhanced Raman modes at 1125 and 1509 cm-1. The Raman spectra of the resulting confined polyene chains are very similar to freestanding isolated trans-polyacetylene prepared by solution methods.

Effect of urea inclusion in diets containing corn dried distillers grains on feedlot cattle performance, carcass characteristics, ruminal fermentation, total tract digestibility, and purine derivatives-to-creatinine index.

Increased availability of rapidly fermentable carbohydrates and a great proportion of corn-derived CP in the diet may result in a degradable intake protein (DIP) deficit. Therefore, ruminal DIP deficit may result from high dietary inclusion of processed corn grain and small to moderate inclusion of corn distillers grains (DG). Two experiments were conducted to evaluate the effect of increasing dietary DIP concentration through the inclusion of urea on feedlot cattle performance, carcass characteristics, ruminal fermentation, total tract digestibility, and purine derivatives-to-creatinine (PDC) index. In Exp. 1, 42 steers (428 ± 5 kg initial BW) were assigned randomly to 1 of 3 diets containing (DM basis) 0 (control [CON]), 0.4 (low urea [LU]), or 0.6% urea (high urea [HU]) to provide 6.4, 7.5, or 8.0% dietary DIP, respectively, and 12% high-moisture corn (HMC), 20% corn dried DG with solubles (DDGS), 10% ryegrass haylage, 2.9% dry supplement, and dry-rolled corn (DRC). Steers were fed ad libitum once daily using a Calan gate system. Carcass-adjusted final BW and DMI were similar among treatments (P ≥ 0.58). Carcass-adjusted ADG was greater (P ≤ 0.04) for the HU diet compared with the LU and CON diets and was similar (P = 0.73) between the LU and CON diets. Carcass-adjusted G:F was greater (P = 0.03) for the HU diet compared with the LU diet, tended (P = 0.09) to be greater compared with the CON diet, and was similar (P = 0.61) between the LU and CON diets. Carcass characteristics were similar (P ≥ 0.34) among treatments. In Exp. 2, 4 ruminally cannulated steers (347 ± 18 kg initial BW) were randomly assigned to a replicated 2 × 2 Latin square design. Steers were fed the same CON or HU diet used in Exp. 1 ad libitum once daily. Differences in the PDC index were used as indicators of differences in microbial CP synthesis. Ruminal pH, OM intake, and starch and CP digestibility were not affected by treatment (P ≥ 0.13). Digestibility of OM and NDF and ruminal concentration of ammonia-N and total VFA were greater (P ≤ 0.04) for the HU diet compared with the CON diet. The PDC index was similar (P = 0.81) between treatments at 2 h before feed delivery: 4% lower and 14% greater for the HU diet compared with the CON diet at 4 and 10 h after feed delivery, respectively (P < 0.01). These results suggest that, due to limited DIP supplied by a DRC- and HMC-based feedlot diet containing 20% DDGS, urea supplementation resulted in improved ruminal fermentation and feed digestibility, which may explain the concurrently improved cattle performance.

4-Me-6E,8E-hexadecadienoic acid isolated from a marine-derived strain of Clonostachys rosea reduces viability of MCF-7 breast cancer cells and gene expression of lipogenic enzymes

Conjugated fatty acids (CFA) have attracted particular attention because of their remarkable biological activities such as anti-carcinogenic, anti-obesity, antithrombotic and anti-atherogenic [1]. The main natural sources of CFA correspond to ruminant milk, algae and seed oils of several plants [2], but fungi have been widely recognized for their production of essential FA such as arachidonic or docosahexaenoic acids which have a major interest in human health and nutrition. Our attention was focused on a marine-derived strain of Clonostachys rosea isolated from marine sediments of the Loire estuary (France), which produced high amounts of triglycerides and an original branched CFA, first identified as 4-Me-6,8-hexadecadienoic acid (4-Me-6,8 – 16:2). In order to optimize the production of this CFA to undergo pharmacological studies, an OSMAC approach has been performed on 7 culture media. Cultures on DCA medium showed the highest production with 19% of total FA. After fungal biomass extraction and saponification of the lipid crude extract, 4-Me-6,8 – 16:2 was purified using urea inclusion and liquid chromatography on AgNO3-impregnated silica gel. The CFA structure was deduced from 1H-NMR and IR analyses confirming the trans configuration of double bonds. When tested against MCF-7 breast cancer cell line, 4-Me-6E,8E-16:2 reduced the viability in a dose dependent manner (up to 75% inhibition after 48h at 100µM). Numerous studies have demonstrated that cell proliferation is associated with hyperactivity of lipogenesis [3, 4]. We have then assessed the effect of 4-Me-6E,8E-16:2 on gene expression of two lipogenic enzymes, the ACC (Acetyl coA Carboxylase) and the FAS (Fatty Acid Synthase). At 50µM and after 24h, expression of ACC and FAS were reduced of 50% and 35%, respectively. These results are promising and need to be completed in order to determine the mechanisms by which 4-Me-6E,8E-16:2 reduce cancer cell proliferation and inhibits the expression of lipogenic enzymes.

Lipozyme RM IM-catalyzed acidolysis of Cinnamomum camphora seed oil with oleic acid to produce human milk fat substitutes enriched in medium-chain fatty acids.

In the present study, a human milk fat substitute (HMFS) enriched in medium-chain fatty acids (MCFAs) was synthesized through acidolysis reaction from Cinnamomum camphora seed oil (CCSO) with oleic acid in a solvent-free system. A commercial immobilized lipase, Lipozyme RM IM, from Rhizomucor miehei, was facilitated as a biocatalyst. Effects of different reaction conditions, including substrate molar ratio, enzyme concentration, reaction temperature, and reaction time were investigated using response surface methodology (RSM) to obtain the optimal oleic acid incorporation. After optimization, results showed that the maximal incorporation of oleic acid into HMFS was 59.68%. Compared with CCSO, medium-chain fatty acids at the sn-2 position of HMFS accounted for >70%, whereas oleic acid was occupied predominantly at the sn-1,3 position (78.69%). Meanwhile, triacylglycerol (TAG) components of OCO (23.93%), CCO (14.94%), LaCO (13.58%), OLaO (12.66%), and OOO (11.13%) were determined as the major TAG species in HMFS. The final optimal reaction conditions were carried out as follows: substrate molar ratio (oleic acid/CCSO), 5:1; enzyme concentration, 12.5% (w/w total reactants); reaction temperature, 60 °C; and reaction time, 28 h. The reusability of Lipozyme RM IM in the acidolysis reaction was also evaluated, and it was found that it could be reused up to 9 times without significant loss of activities. Urea inclusion method was used to separate and purify the synthetic product. As the ratio of HMFS/urea increased to 1:2, the acid value lowered to the minimum. In a scale-up experiment, the contents of TAG and total tocopherols in HMFS (modified CCSO) were 77.28% and 12.27 mg/100 g, respectively. All of the physicochemical indices of purified product were within food standards. Therefore, such a MCFA-enriched HMFS produced by using the acidolysis method might have potential application in the infant formula industry.

Anti-thrombotic effects of α-linolenic acid isolated from Zanthoxylum bungeanum Maxim seeds.

BackgroundThe current study was to evaluate the anti-thrombotic effect of alpha-linolenic acid (ALA) which was isolated and purified from Jiaomu in vivo.MethodsThe seeds were crushed and subsequently subjected to saponification, acid hydrolysis, gradient freezing, urea inclusion and complexation of silver nitrate to obtain the unsaturated fatty acids. The chemical characteristics of isolated ALA were validated by 1HNMR, 13CNMR and mass spectrometry, and then the anti-thrombotic effect of ALA and its mixture with linoleic acid (1:1) were evaluated in the following experiments.ResultsThe alpha-linolenic acid was isolated and purified from Jiaomu through our newly established methods. ALA and its mixture with linoleic acid can prolong the hemorrhage and coagulation time as well as enhanced the survival rate of mice subjected to collagen-adrenaline induced thrombosis. In addition, the thrombosis on A-V bypass and platelet aggregation of rats will be reduced after treated with ALA or its mixture, and the expression level of Akt and PI3K protein decreased 26% and 31%, respectively.ConclusionsWe designed and optimized a very simple and high-yield procedure to isolate ALA and linoleic acid mixture from seeds of Zanthoxylum bungeanum Maxim and demonstrated that such mixture can obtain a good anti-thrombotic effect through the modulation of PI3K/Akt signaling.

The changeable nature of urea inclusion compounds.

Urea inclusion compounds (UICs), the β-phase of urea, have been known only since 1949 and have revealed various structural and behavioural characteristics of interest, largely influenced by the type of guest molecule present in the crystal. These structures have a hexagonally symmetrical honeycomb structure of a hydrogen-bonded urea network encapsulating the guest molecules, a defining motif of these clathrates. The simplest of this class contains an alkane guest (C7-C20), creating an incommensurate relationship between host and guest and a significantly disordered crystal structure with respect to the guest. As a result, diffuse scattering is typical in the diffraction patterns of UICs. As the guest molecules are altered, so too is the behaviour of the host network. With certain dihaloalkanes for example, the guest may coil into an atypical conformation in order to present a commensurate relationship with the host. This increase in guest order creates a distortion of the host network away from hexagonal symmetry, creating an internal stress which causes domain switching within the system. A number of different effects such as this can be seen on changing the guest molecule, ferroelasticity being an example for certain diketone guests. In this work we are exploring examples of UICs which, due to unusual interaction between the host and guest, display atypical structural features, symmetry or behaviour. These crystal structures are under investigation at a range of temperatures and pressures, by both X-ray and neutron diffraction techniques in order to fully understand the nature and bonding of UICs.

Morphology and crystalline structure of inclusion compounds formed between poly(ethylene glycol) and urea

The poly(ethylene glycol) (PEG, with M w 2000)-urea inclusion compound (IC) crystallized at high temperature region showed two typical orientations, flat-on and edge-on crystals. 2D-XRD and polarized FTIR spectroscopy revealed that the PEG chains within urea channels were perpendicular to the substrate in flat-on oriented crystals, while PEG chain axes were parallel to the substrate and lay along the growth direction in the edge-on crystals. FTIR absorption bands of PEG in the ICs are sensitive to orientation of the crystals. A scheme of PEG chain packing in the urea IC channel was proposed, which could explain the orientation of the crystal nucleus causing the two types of morphologies. Furthermore, functioning of PEG2000 chain end with analine had significantly influence on the morphology and orientation of the inclusion compound crystals, due to the defects caused by large terminal groups included in the urea channel.

Inclusion of urea in a 59FeEDTA solution stimulated leaf penetration and translocation of 59Fe within wheat plants

The role of urea in the translocation of (59) Fe from (59) FeEDTA-treated leaves was studied in durum wheat (Triticum durum) grown for 2 weeks in nutrient solution and until grain maturation in soil culture. Five-cm long tips of the first leaf of young wheat seedlings or flag leaves at the early milk stage were immersed twice daily for 10 s in (59) FeEDTA solutions containing increasing amounts of urea (0, 0.2, 0.4 and 0.8% w/v) over 5 days. In the experiment with young wheat seedlings, urea inclusion in the (59) FeEDTA solution increased significantly translocation of (59) Fe from the treated leaf into roots and the untreated part of shoots. When (59) Fe-treated leaves were induced into senescence by keeping them in the dark, there was a strong (59) Fe translocation from these leaves. Adding urea to the (59) Fe solution did not result in an additional increase in Fe translocation from the dark-induced senescent leaves. In the experiment conducted in the greenhouse in soil culture until grain maturation, translocation of (59) Fe from the flag leaves into grains was also strongly promoted by urea, whereas (59) Fe translocation from flag leaves into the untreated shoot was low and not affected by urea. In conclusion, urea contributes to transportation of the leaf-absorbed Fe into sink organs. Probably, nitrogen compounds formed after assimilation of foliar-applied urea (such as amino acids) contributed to Fe chelation and translocation to grains in wheat.

Thermal Properties and Transition Behavior of Host-Guest Compounds Under High Pressure

The thermal properties and transition behavior of the host-guest inclusion compounds: urea, thiourea, Dianin’s compound, clathrate hydrates and hydroquinone have been reviewed. In particular, we summarize their thermal conductivities, heat capacities and transitions at high pressures. Two of the systems: urea inclusion compounds and clathrate hydrates, show unusual glass-like thermal conductivity κ, i.e. their κ is low and only weakly dependent on temperature despite their crystalline structure. Moreover, results for κ of Dianin’s compound with guests such as ethanol and CCl4 indicate a change from glass-like κ at atmospheric pressure to crystalline-like κ at elevated pressure, whereas κ of hydroquinone and thiourea inclusion compounds appears not to have been studied. Despite the technological and fundamental importance of the unusual glass-like κ, e.g. the use of inclusion compounds as structural model systems for finding improved thermoelectrical materials, the origin of the glass-like κ is not established. More specifically, the commonly employed rattling model, in which rattling guest motions cause resonance scattering of the acoustic host phonons, has recently been challenged, and we discuss alternative models. Heat capacity studies of these compounds reveal numerous transitions, which are associated with guest and host disorder-order transitions upon cooling and pressurization. A transition in hydroquinone may be of second order, or have only a small first-order component, which can explain discrepancies in the observed transition behavior. On pressurization at low temperatures, clathrate hydrates collapse to an amorphous state, which appears to be a glassy state of a water solution with perfectly spaced solute molecules. Keywords: Glass-like behavior, glassy water solution, heat capacity, high pressure, inclusion compound, phase transition, phase diagram, pressure induced amorphization, structure, thermal conductivity.

Growth characteristic, guest distribution, guest ordering and the stability of urea inclusion compounds with 1-decene, n-decane and mixture of 1-decene and n-decane

Growth characteristics of urea inclusion compounds with 1-decene, n-decane and mixture of 1-decene and n-decane (relative mass ratio=1:1) were studied by CCD high-speed Camera. The present studies show that the speed of UICs growth in tunnel direction is faster than in vertical direction and the length of UICs with 1-decene is shorter than UICs with n-decane, and the length of UICs with mixture is between them due to the influence of the vinyl in 1-decene. The value of R=I(CH2)/I(CH3) and M=I(CHCH2)/I(CH3) in FTIR spectrum of UICs increasing with growth time demonstrates that urea prefers to include n-decane than 1-decene. 13C CP/MAS NMR studies of UICs indicate that the arrangement of 1-decene in UICs is CH3⋯CH3 and CHCH2⋯CH2CH. The arrangement of 1-decene in UICs leads to short chain of UICs with 1-decene in tunnel direction. The 13C CP/MAS NMR spectra of UICs with MIX reveal that there are three different types of arrangement: CH3⋯CH3, CHCH2⋯CH3 and CHCH2⋯CH2CH. The methods of FTIR and DSC were used to test the stability of UICs with different guests. The result shows that UICs with n-decane are stable than UICs with 1-decene. And the stability of UICs with mixture is in the middle.

Study of moisture sorption behavior of urea inclusion compounds with aliphatic guests and with linear polymers

Urea is known to form stable inclusion compounds (IC) with a wide variety of guests, which include aliphatic organic substances as well as linear polymers. Urea in its native form is also known to undergo deliquescence when exposed to an atmosphere of higher water activity. The purpose of the present study was to determine and compare the moisture sorption profiles of the uncomplexed urea as well as ICs of urea with different guests. Urea ICs with two types of guest moieties were prepared, that is, either monosubstituted unbranched alkane derivatives possessing an anchor length of 16 carbons or linear polymer poly (ethylene glycol) of different molecular weights. The formation of ICs was confirmed through thermal analysis and powder X-ray diffraction/single crystal diffraction. The ICs were exposed to environment of varying water activity in dynamic water sorption analyzer, and the rate and extent of moisture uptake were determined. Critical relative humidity of urea and representative ICs was determined by two techniques. Urea ICs were found to demonstrate greater resistant to deliquescence as exhibited by increase in critical relative humidity in comparison with uncomplexed urea. Thermodynamic considerations involved in the process of deliquescence are discussed. Copyright © 2013 John Wiley & Sons, Ltd.

Commensurate Urea Inclusion Crystals with the Guest (E,E)-1,4-Diiodo-1,3-Butadiene

The urea inclusion compound (UIC) with (E,E)-1,4-diiodo-1,3-butadiene (DIBD) as a guest (DIBD:UIC) has been prepared and crystallographically characterized at 90 and 298 K as a rare example of a commensurate, fully ordered UIC. The crystal shows nearly hexagonal channels in the monoclinic space group P21/n. The DIBD guest molecules are arranged end-to-end with the nonbonding iodine atoms in van der Waals contact. The guest structure is compared with that for DIBD at 90 K and with computations for the periodic UIC and isolated DIBD molecule.

Consumo e digestibilidade de nutrientes em bovinos submetidos a diferentes níveis de uréia

The dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), crude protein (CP), non fiber carbohydrate (NFC), eter extract (EE) intake and apparent digestibility and total digestible nutrients (TDN) in cattle fed with Brachiaria brizantha La Liberdad, low quality hay, with increasing urea levels, were evaluated. Were used five Nellore steers, male, castrated, canuled, distributed in latin square among the treatments 1: control, only hay and increasing urea levels added directly in the rumen aiming to increase in 2: 2 %, 3: 4 %, 4: 6 % and 5: 8 % the CP in the diet. The DM, OM and NDF intakes linearly increased when raised from 3.4 to 9.9 % CP in the diet and decreased in 11.6 % CP. The NFC and EE intakes didnt differ. The urea inclusion didnt influenced the DM, OM, NDF and NFC digestibilities. The CP digestibility showed quadratic effect. To increase DM intake by cattle fed diets based on exclusive hay of Brachiaria brizantha La Liberdad with low protein content (2.9 % CP) and high content of neutral detergent fiber (NDF 77 %), it is suggested the CP suplementation with urea up to the level of 10 % CP.

ISOLASI ASAM-9Z,12Z,15Z-OKTADEKATRIENOAT DARI BIJI SELASIH (Ocimum basilicum)

&lt;p&gt;The α-linolenic acid (9,12,15-octadecatrieonic acid) is omega-3 fatty acid that more active than other fatty acids to inhibit cell membrane damages, formation and growth of brain functions, antiinflamatory and prevent several cronic deseases like lung desease and arthrytis. Some research explain that geometri of omega-3 fatty acids had effect on its bioactivity. This research purpose was to isolate α-linolenic acid with geometry &lt;em&gt;Z,Z,Z &lt;/em&gt;(&lt;em&gt;9Z,12Z,15Z&lt;/em&gt;-oktadekatrienoat).&lt;/p&gt;&lt;p&gt;&lt;em&gt;O. basilicum &lt;/em&gt;seeds oil was isolated from &lt;em&gt;O. basilicum &lt;/em&gt;seeds using Soxhlet extraction with n-hexane, then hidrolized by 12 % solution of KOH in aquadest. The α-linolenic acid was separated from other fatty acids by urea inclusion methods. The optimum condition of urea inclusion was determined in various temperature (+ 5, + 3, + 1, + (-1), + (-3), + (-5))&lt;sup&gt;0&lt;/sup&gt;C and ratio of fatty acid : urea 1:1; 1:1,5; 1:2; 1:2,5; 1:3; 1:3,5; 1:4.&lt;/p&gt;&lt;p&gt;From this research, extraction of &lt;em&gt;O. basilicum &lt;/em&gt;seeds oil with n-hexane as solvent resulted clear yellow-brown oil with refractive indeks 1,466 and density 0,855 g/mL. Gas Chromatography (GC) analysis of fatty acids hidrolyzed from &lt;em&gt;O. basilicum &lt;/em&gt;oil showed peak at t&lt;sub&gt;R&lt;/sub&gt;= 19,949 minutes with relative percentage 70,72 %. Base on Mass Spectrum (MS), the fragmentation of this compound, with t&lt;sub&gt;R&lt;/sub&gt;= 19,949 minutes, was identic with &lt;em&gt;9Z,12Z,15Z&lt;/em&gt;-oktadecatrienoic acid.Isolation of α-linolenic acid from other fatty acids using urea inclusion at temperature 0-2 &lt;sup&gt;0&lt;/sup&gt;C dan rasio fatty acid: urea 1:1,5 showed nonadduct fraction contains compound with t&lt;sub&gt;R&lt;/sub&gt;= 19,980 minutes and relative percentage 88,51 %. Base on Mass Spectrum (MS), the fragmentation of this compound, with t&lt;sub&gt;R&lt;/sub&gt;= 19,980 minutes, was identic with &lt;em&gt;9Z,12Z,15Z&lt;/em&gt;-oktadecatrienoic acid.&lt;/p&gt;

Optimizing Conditions for the Purification of Omega-3 Fatty Acids from the By-product of Tuna Canning Processing

This research studied the optimization conditions for separation and purification of omega-3 (ω-3) fatty acids from the by-product of tuna canning processing by urea crystallization. Crystallization reaction conditions of urea inclusion (urea to fatty acid ratio (X 1) and crystallization time (X 2)) were optimized using the Response Surface Methodology (RSM) and a model was developed. Optimization results showed a quadratic polynomial regression equation of Y = 24.44X 1 + 5.65X2 - 8.71X1 2 - 0.19X2 2 + 1.171X1X2 - 12.95. The maximum response was obtained at an urea to fatty acid ratio of 2.99:1 and a crystallization time of 23.64 h and predicted response of 90.44%. Analysis of variance showed that the urea to fatty acid ratio and crystallization time affected the response. Verification under optimal conditions showed that the purity of ω-3 fatty acids was 89.64% and the enrichment was 2.85 fold. Verification result revealed that the predicted value from this model was reasonably close to the experimentally observed value. The urea crystallization process changed oil quality parameters including oxidation level (peroxide, anisidin, and totox values), Fe, Cu and P concentrations and moisture content and this were mostly due to the saponification process before urea crystallization.

Enrichment of Arachidonic Acid for the Enzymatic Synthesis of Arachidonoyl Ethanolamide

AbstractArachidonoyl ethanolamide is an endogenous cannabinoid neurotransmitter that potentially has therapeutic properties. In this study, we report an enzymatic method to synthesize this bioactive ethanolamide. First, free fatty acids were obtained from arachidonic acid‐rich oil and then arachidonic acid was enriched by urea inclusion and AgNO3 solution fractionation. Arachidonic acid content was increased from 40.2 to 78.4 % with 27.6 ± 1.8 % total fatty acid mass yield (w/w, relative to total free fatty acid) after urea inclusion. Purification of arachidonic acid by AgNO3 solution fractionation was optimized, and under the optimal conditions, a product with 90.7 % arachidonic acid was obtained with 80.4 % mass yield (w/w, relative to total free fatty acid). Finally, arachidonoyl ethanolamide was synthesized by reacting the purified arachidonic acid with ethanolamine in hexane using Novozym 435 lipase of Novozymes America (Blair, NE), which resulted in the formation of 88.4 ± 0.6 % arachidonoyl ethanolamide with 72.7 ± 2.2 % mass yield. The main novelties of this study are the enrichment of polyunsaturated fatty acids by AgNO3 solution fractionation which has received little attention in recent years, and this is the first time the synthesis of arachidonoyl ethanolamide is reported.

Comportamento ingestivo de vacas primíparas das raças Guzerá e Sindi recebendo dietas com diferentes níveis de ureia

Objetivou-se com este trabalho avaliar parâmetros de comportamento ingestivo de vacas primíparas das raças Guzerá e Sindi recebendo dietas com diferentes níveis de inclusão de ureia, em substituição ao farelo de soja, e da cana-de-açúcar, em substituição ao capim elefante. Foram utilizadas oito vacas primíparas, sendo quatro da raça Guzerá e quatro da raça Sindi em lactação, distribuídas em dois quadrados latinos 4x4. Os tratamentos experimentais consistiram em: T1 (0,0 cana-de-açúcar + 0,0% ureia), T2 (13,0% cana-de-açúcar + 0,6% ureia), T3 (26,2% cana-de-açúcar + 1,2% ureia) e T4 (39,4% cana-de-açúcar + 1,8% ureia), na matéria seca. Os animais foram observados a cada cinco minutos, durante 24 horas, para determinação do tempo despendido em alimentação, ruminação e ócio. Não foi observada diferença significativa (P&gt;0,05) para os tempos médios despendidos com as variáveis comportamentais alimentação, ruminação e ócio, à medida que foram aumentados os níveis de inclusão da ureia e cana-de-açúcar nas dietas. O tempo de mastigação total foi maior para os animais da raça Sindi, quando comparado ao dos animais da raça Guzerá. Animais da raça Guzerá apresentaram maior eficiência de alimentação em (g MS/h) e ruminação, quando expressa em (g MS h-1) e (g FDN h-1), quando comparada com a raça Sindi. À medida que se aumentam os níveis de inclusão da ureia e cana de açúcar na dieta, há um decréscimo da eficiência de ruminação expresso em (g FDN h-1).

Adhesion of gold and silver nanoparticles onto urea–alkylamine inclusion compounds

We report the synthesis and characterization of a new series of urea inclusion compounds containing primary alkylamine (octyl, decyl and dodecyl) as guests, as well as the deposition of gold and silver nanoparticles onto the crystalline surface of these complexes. X-ray diffraction confirms the inclusion process of the amine in the urea cavities. The structures determined for the three complexes correspond to a hexagonal channel structure with space group P6122. Alkylamine–urea stoichiometric ratios in all cases satisfy the relationship 1:3n (n = 2 for octylamine and 3 for decylamine and dodecylamine), determined by elemental analysis. The deposition of gold and silver nanoparticles by the magnetron sputtering technique onto microcrystals of the complexes was analyzed by Diffuse Reflectance Spectroscopy, showing characteristic surface plasmon resonance for metal nanoparticles. Transmission electron microscopy demonstrates the presence of metal nanoparticles (MNPs) in a size range between 5 and 60 nm for gold and between 5 and 20 nm for silver, and furthermore, in some cases it shows vestiges of a hexagonal arrangement of the MNPs. X-ray diffraction and IR measurements demonstrate that the basic structure of the matrix remains unchanged after the MNPs adhesion. IR also shows increased broadening and intensity of the characteristic NH2 bending frequencies (1,597 cm−1) when the MNPs interact with the inclusion compounds. We conclude that the interactions between the inclusion compounds and metal nanoparticles occurs mainly through the amino groups of the guest molecules that can emerge from the entrance of the inclusion compound cavities attracted by the metallic nanoparticles, in opposition to the restoring van der Waals interactions present inside channels, which increase with increasing chain length of the guest molecules. Schematic representation of urea inclusion compounds containing primary alkylamine (octyl, decyl and dodecyl) as guests and the deposition of gold and silver nanoparticles onto the crystalline surface of these complexes .

Behavior of Poly(ε-caprolactone)s (PCLs) Coalesced from Their Stoichiometric Urea Inclusion Compounds and Their Use as Nucleants for Crystallizing PCL Melts: Dependence on PCL Molecular Weights

We have formed noncovalent inclusion compounds (ICs) between guest poly(ε-caprolactone) (PCL) chains, with molecular weights ranging from ∼2000 to 80 000 g/mol, and host urea (U). Upon careful removal of the U host, each of the guest PCL chains were coalesced from their U-IC crystals to produce coalesced samples (c-PCLs). As previously observed for PCL and other polymer guests when coalesced from their ICs formed with host cyclodextrins (CDs), upon cooling from their melts, PCLs coalesced from their U-ICs also show enhanced abilities to crystallize, regardless of their molecular weight. Also consistent with polymer guests, including PCL, that were coalesced from their CD-ICs, c-PCLs obtained from their U-ICs retain their enhanced abilities to crystallize even after spending long times (weeks or more) in the melt. Because, unlike CD hosts, U does not thread over guest polymer chains in their ICs, we conclude that the enhanced ability of c-PCLs to crystallize from their melts upon removal of either host from their ICs is solely a consequence of their coalesced conformations/structures/morphologies, which are stable to prolonged melt-annealing. Furthermore, because c-PCLs with chain lengths well below and well above those corresponding to the entanglement molecular weight of PCL behave similarly, we conclude that their enhanced ability to crystallize from the melt is likely an exclusive consequence of the extended and unentangled arrangement of their coalesced chains. In addition, c-PCLs obtained from their U-ICs are observed to effectively act as self-nucleants, when added in small amounts to as-received PCLs, to produce nuc-PCLs, which like neat c-PCLs exhibit an enhanced ability to melt-crystallize.

An initial investigation on rumen fermentation pattern and methane emission of sheep offered diets containing urea or nitrate as the nitrogen source

The effects of dietary nitrate and of urea on rumen fermentation pattern and enteric methane production were investigated using 4-month-old ewe lambs. Ten lambs were allocated into two groups (n = 5) and each group was offered one of two isonitrogenous and isoenergetic diets containing either 1.5% urea (T1) or 3% calcium nitrate (T2). Methane production was estimated using open-circuit respiration chambers after 6 weeks of feeding. No difference in nitrogen (N) balance, apparent digestibility of N or microbial N outflow existed between treatments (P &gt; 0.05). Animals offered the T2 diet lost less energy through methane than did those fed the T1 diet (P &lt; 0.05). Total volatile fatty acid concentration, molar proportion of propionate, and the molar ratio of acetate to propionate in rumen fluid were not affected by dietary N source. Compared with urea inclusion, nitrate inclusion caused a significantly higher acetate and lower butyrate percentage in rumen volatile fatty acid. Nitrate supplementation tended to lower methane production by ~7.7 L/day relative to urea supplementation (P = 0.06). Methane yield (L/kg DM intake) was reduced (P &lt; 0.05) by 35.4% when 1.5% urea was replaced by 3% calcium nitrate in the diet. Emission intensity (L methane/kg liveweight gain) was ~17.3% lower in the nitrate-supplemented sheep when compared with urea-fed sheep; however, the reduction was not statistically significant (P &gt; 0.05). This study confirms that the presence of nitrate in the diet inhibits enteric methane production. As no clinical symptoms of nitrite toxicity were observed and sheep receiving nitrate-supplemented diet had similar growth to those consuming urea-supplemented diet, it is concluded that 3% calcium nitrate can replace 1.5% urea as a means of meeting ruminal N requirements and of reducing enteric methane emissions from sheep, provided animals are acclimated to nitrate gradually.