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1.
J Anim Sci ; 1022024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38558022

RESUMO

Variation in feed intake results in nearly 20% of sows consuming less than the recommended lysine (Lys) intake for lactating sows. The Lys requirement for lactating sows is based on litter size and piglet average daily gain which influences milk production. Litter size continues to increase every year causing the need for routine reevaluation of nutrient requirements. If dietary inclusion levels are not continuously adjusted this can lead to inadequate daily Lys and energy intake and may negatively impact sow body condition and litter performance. The objective was to characterize the average daily feed intake (ADFI) of sows and define feed intake patterns and their effects on sow body weight, farrowing performance, litter performance, and subsequent farrowing performance. ADFI during lactation was recorded for 4,248 sows from 7 independent research studies. Data collection occurred from November 2021 through November 2023 at a commercial breed-to-wean facility in western Illinois. Each sow was categorized as: consistently low intake (< 5.5 kg/d) throughout the lactation (LLL); low intakes (< 5 kg/d) in the first week, then gradually increased throughout the rest of the lactation period (LHH); gradual increase in intake throughout lactation with no drop and a peak intake after day 10 of lactation (gradual); rapid increase in intake with no drop and the peak intake met before day 10 (rapid); a major drop in feed intake (> 1.6 kg decrease for ≥ 2 d) any time during lactation (MAJOR); minor drop (≤ 1.6 kg for ≥ 2 d; MINOR). Sows were also separated into low (quartile 1; ≤ 25%), average (quartile 2 through 3), or high feed intake (quartile 4; ≥ 75%) by parity (P1, P2, P3+). Sows in the LLL category were younger in parity, had the greatest preweaned mortality, weaned the lightest average pigs, and experienced the greatest loss in body weight percentage compared with sows in all other feed intake categories. Furthermore, sows in the LLL and LHH categories had one fewer subsequent pig born compared with sows in the other four categories. These data support historical findings that feed intake patterns directly contribute to current litter farrowing performance. Lactation intake patterns also influence subsequent farrowing performance. Identifying under-consuming sows that are likely Lys and energy deficient allows producers opportunities to promote consistent, adequate daily intakes to these groups and mitigate negative impacts on sow and litter performance.


This study investigated different sow feed intake patterns during lactation and average daily feed intakes within parity on current and subsequent farrowing and litter performance. Findings revealed sows that have consistently low intake throughout the lactation period have a significant reduction in average pig wean weight, a greater percentage of pre-wean mortality, and take an additional day or longer to return to estrus compared with sows that have average or above feed intake throughout the lactation period. Specifically, older parity sows were heavier, had greater feed intake, nursed heavier litters, and had litters with less preweaned mortality compared with younger parity sows. The average pig weaned weight and subsequent total pigs born improved as intake increased within parity. Prewean mortality decreased as feed intake increased within parity. These findings highlight the importance of ensuring sows are not only eating enough, but that they are consuming more than average when possible, to continually improve current and subsequent farrowing and litter performance. This study provides important information that will allow producers to target specific under-consuming sows and then promote consistent and high daily lactation intakes. Targeting these potentially nutrient-restricted sows may help reduce negative impacts on sow and litter performance.


Assuntos
Ração Animal , Ingestão de Alimentos , Lactação , Animais , Feminino , Lactação/fisiologia , Suínos/fisiologia , Gravidez , Ração Animal/análise , Dieta/veterinária , Tamanho da Ninhada de Vivíparos , Fenômenos Fisiológicos da Nutrição Animal
2.
Anticancer Res ; 44(5): 1955-1962, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38677771

RESUMO

BACKGROUND/AIM: The epidermal growth factor receptor (EGFR) is over-expressed in several types of cancer, and monoclonal antibody therapy has been the strategy that has shown the best results. This study focused on the construction of a humanized single chain antibody (huscFv) directed against EGFR (HER1). MATERIALS AND METHODS: The CDR grafting method was used to incorporate murine complementarity determining regions (CDRs) of cetuximab into human sequences. A dot blot assay was used to examine the affinity of the huscFv secreted by HEK293T for EGFR. The inhibitory effect on the viability of A549 cells was evaluated using the WST-1 assay. RESULTS: The incorporation of murine CDRs of cetuximab into human sequences increased the degree of humanness by 16.4%. The increase in the humanization of scFv did not affect the affinity for EGFR. Metformin had a dose-dependent effect, with an IC50 of 46 mM, and in combination with huscFv, the cell viability decreased by 45% compared to the 15% demonstrated by huscFv alone. CONCLUSION: The CDR grafting technique is efficient for the humanization of scFv, maintaining its affinity for EGFR and demonstrating its inhibitory effect when combined with metformin in A549 cells.


Assuntos
Receptores ErbB , Metformina , Anticorpos de Cadeia Única , Humanos , Metformina/farmacologia , Receptores ErbB/imunologia , Receptores ErbB/antagonistas & inibidores , Células A549 , Anticorpos de Cadeia Única/farmacologia , Anticorpos de Cadeia Única/imunologia , Células HEK293 , Cetuximab/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Anticorpos Monoclonais Humanizados/farmacologia , Animais , Camundongos , Regiões Determinantes de Complementaridade/imunologia , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/imunologia
3.
Toxins (Basel) ; 16(3)2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38535808

RESUMO

Central America is home to one of the most abundant herpetofauna in the Americas, occupying only 7% of the continent's total area. Vipers and lizards are among the most relevant venomous animals in medical practice due to the consequences of envenomation from the bite of these animals. A great diversity of biomolecules with immense therapeutic and biotechnological value is contained in their venom. This paper describes the prominent leading representatives of the family Viperidae, emphasizing their morphology, distribution, habitat, feeding, and venom composition, as well as the biotechnological application of some isolated components from the venom of the animals from these families, focusing on molecules with potential anti-thrombotic action. We present the leading protein families that interfere with blood clotting, platelet activity, or the endothelium pro-thrombotic profile. In conclusion, Central America is an endemic region of venomous animals that can provide many molecules for biotechnological applications.


Assuntos
Trombose , Animais , América Central , Coagulação Sanguínea , Biotecnologia , Plaquetas
4.
JACC Case Rep ; 29(4): 102210, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38379656

RESUMO

We present a case of a full-term newborn with complex congenital heart defects, including single-ventricle physiology and discontinuous pulmonary arteries. Prompt surgical intervention was performed, which involved pulmonary neoconfluence with autologous pericardium graft and systemic-to-pulmonary shunt placement. However, postoperative complications required stenting to address pulmonary artery stenosis.

6.
Int J Biol Macromol ; 255: 128078, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37972836

RESUMO

Disintegrins are a family of cysteine-rich small proteins that were first identified in snake venom. The high divergence of disintegrins gave rise to a plethora of functions, all related to the interaction with integrins. Disintegrins evolved to interact selectively with different integrins, eliciting many physiological outcomes and being promising candidates for the therapy of many pathologies. We used NMR to determine the structure and dynamics of the recombinant disintegrin jarastatin (rJast) and its interaction with the cancer-related integrin αVß3. rJast displayed the canonical fold of a medium-sized disintegrin and showed complex dynamic in multiple timescales. We used NMR experiments to map the interaction of rJast with αVß3, and molecular docking followed by molecular dynamics (MD) simulation to describe the first structural model of a disintegrin/integrin complex. We showed that not only the RGD loop participates in the interaction, but also the N-terminal domain. rJast plasticity was essential for the interaction with αVß3 and correlated with the main modes of motion depicted in the MD trajectories. In summary, our study provides novel structural insights that enhance our comprehension of the mechanisms underlying disintegrin functionality.


Assuntos
Desintegrinas , Integrina alfaVbeta3 , Desintegrinas/química , Integrina alfaVbeta3/metabolismo , Simulação de Acoplamento Molecular , Sequência de Aminoácidos , Integrinas/metabolismo
7.
Cardiol Young ; 34(2): 314-318, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37403735

RESUMO

The use of prostaglandin E1 is well documented in ductus arteriosus-dependent CHD or in neonatal pulmonary pathologies that cause severe pulmonary hypertension. The intravenous infusion is well established in loading infusion and maintenance with an onset of action of 30 minutes until 2 hours or even more. Our aim is to report three patients with pulmonary atresia that presented hypercyanotic spell due to a ductal spasm during cardiac catheterisation in whom the administration of a bolus of alprostadil reversed the spasm and increased pulmonary flow, immediately stabilising the condition of the patients allowing subsequent successful stent placement with no serious complications or sequelae after the administration of the bolus. More studies are needed to make a recommendation regarding the use of alprostadil in bolus in cases where the ductal spasm might jeopardise the life of the patient.


Assuntos
Permeabilidade do Canal Arterial , Canal Arterial , Cardiopatias Congênitas , Recém-Nascido , Humanos , Alprostadil/uso terapêutico , Permeabilidade do Canal Arterial/tratamento farmacológico , Espasmo
8.
Cardiol Young ; 33(12): 2649-2650, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37905344

RESUMO

Ten-day-old neonate who underwent correction of interrupted aortic arch developed a giant early post-surgical aneurysm. To our knowledge, this unusual complication has been only reported as a late complication.


Assuntos
Aneurisma , Coartação Aórtica , Lactente , Recém-Nascido , Humanos , Aorta Torácica/diagnóstico por imagem , Aorta Torácica/cirurgia , Coartação Aórtica/cirurgia
9.
Heliyon ; 9(9): e19642, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37810128

RESUMO

In recent years, the avocado has been one of the most dynamic fruits in the world market. In particular, cv. Hass stands out due to its productivity, nutritional quality, and acceptance. Under tropical conditions, weather elements, especially air temperature, and precipitation, affect the productivity and quality of cv. Hass. However, in tropical environments, many relationships between weather and phenological aspects of this cultivar are still unknown. Given this situation, our aim was to identify the variation and degree of association between the phenology of avocado cv. Hass and thermal time (TT) under low-latitude conditions. Eight commercial fields planted with cv. Hass grafted onto Antillean genotypes, located in an altitudinal transect between 1,700 and 2,500 m, were evaluated. The evaluation was carried out for three years and was focused on determining the differences in avocado phenological patterns associated with different environmental variables monitored by weather stations at each location. Air temperature data were used to calculate the base temperature (BT) using different methods for all phenological stages. Later the TT was determined for each stage and all locations. The results show that the duration of each phenological stage varies as a function of elevation (air temperature) and that the phenological stages overlap at the regional, crop field, and plant levels at different periods of the year, generating a high phenological variability but with specific patterns associated with temperature and precipitation. The BT for each phenological stage varied between 0.3 and 7.5 °C, and TT was found to vary depending on the method of calculation. Our work suggests that the generalization of a BT of 10 °C is not applicable for avocado cv. Hass crops under tropical conditions, specifically in the case of Colombia. Detailed studies of phenological relationships with respect to climatic variables will allow a better approximation of the productive behavior of avocado cv. Hass.

10.
Int J Mol Sci ; 24(18)2023 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-37762277

RESUMO

Aberrant expression of the tight junction protein claudin 6 (CLDN6) is a hallmark of gastric cancer progression. Its expression is regulated by the cAMP response element-binding protein (CREB). In gastric cancer induced by Helicobacter pylori (H. pylori) there is no information regarding what transcription factors induce/upregulate the expression of CLDN6. We aimed to identify whether CREB and Yin Yang1 (YY1) regulate the expression of CLDN6 and the site where they bind to the promoter sequence. Bioinformatics analysis, H. pylori lipopolysaccharide (LPS), YY1 and CREB silencing, Western blot, luciferase assays, and chromatin immunoprecipitation experiments were performed using the stomach gastric adenocarcinoma cell line AGS. A gen reporter assay suggested that the initial 2000 bp contains the regulatory sequence associated with CLDN6 transcription; the luciferase assay demonstrated three different regions with transcriptional activity, but the -901 to -1421 bp region displayed the maximal transcriptional activity in response to LPS. Fragment 1279-1421 showed CREB and, surprisingly, YY1 occupancy. Sequential Chromatin Immunoprecipitation (ChIP) experiments confirmed that YY1 and CREB interact in the 1279-1421 region. Our results suggest that CLDN6 expression is regulated by the binding of YY1 and CREB in the 901-1421 enhancer, in which a non-described interaction of YY1 with CREB was established in the 1279-1421 region.


Assuntos
Adenocarcinoma , Helicobacter pylori , Neoplasias Gástricas , Humanos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Lipopolissacarídeos/farmacologia , Fator de Transcrição YY1/genética
11.
Transl Anim Sci ; 7(1): txad070, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37465568

RESUMO

The objective of this experiment was to evaluate the impact of lowering floor space allowance in finishing hogs from 65 to 120 kg when fed high- vs. low-energy diets on growth performance. Eighty-eight mixed-sex pens with 24 ±â€…1 pigs per pen were randomly assigned by weight in a complete block design to one of eight treatments in a 2 × 4 factorial arrangement with two energy levels: low (LE, 3267 ±â€…15 kcal/kg) vs. high (HE, 3389 ±â€…15 kcal/kg) accomplished through fat inclusion; and four floor space allowances: 0.6, 0.63, 0.65, and 0.67 m2/pig. Assigned floor space was accomplished by moveable gates in the rear of the pen which were adjusted at each pig removal until the marketing phase. Pen weight was measured at days 0, 29, and 48, with feed disappearance measured at days 29 and 48 to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (GF). Data were analyzed by pen (SAS 9.4, Cary, NC), as repeated measures, with the fixed effects of floor space allowance, dietary energy level, and the interaction between floor space allowance and energy level. For the overall experiment, decreased floor space had no effect (P > 0.1) on ADG, ADFI, or GF. Energy had a significant effect (P < 0.01) on ADFI (3.17 vs. 3.12 kg for LE and HE, respectively) and GF (0.35 and 0.36 for LE and HE, respectively), and tended to impact (P = 0.08) ADG (1.12 vs. 1.13 kg, for LE and HE, respectively). In conclusion, reducing space allowance from 0.67 m2 down to 0.6 m2 did not affect the growth performance of pigs from 65 to 120 kg. Pigs fed LE consumed more than the HE diets but had generally similar growth and no difference in body weight.

12.
Rev Med Inst Mex Seguro Soc ; 61(2): 251-255, 2023 Mar 01.
Artigo em Espanhol | MEDLINE | ID: mdl-37200622

RESUMO

Background: The indiscriminate application of substances for aesthetic purposes, such as silicone in breast implants, leads to the production of common local signs such as inflammation, skin irregularities, edema, erythema, vascular neoformations, and ulcers, which can evolve into general symptoms such as fever, asthenia, weakness, arthralgia or activate the immune system abnormally, causing the appearance of autoimmune diseases. This set of signs and symptoms is called adjuvant-induced autoimmune/inflammatory syndrome. Clinical case: We present the case of a 50-year-old woman with a history of silicone-based breast implants who spontaneously developed a hemorrhagic coagulopathy, type A acquired hemophilia was documented, that is, autoantibodies against coagulation factor VIII. Thanks to the work of a multidisciplinary team, it is possible to successfully diagnose and treat the patient with bridging agents, implant removal and management of associated symptoms. Conclusion: the importance of knowing the pathology is recognized, which, although it is rare, when it occurs has a high mortality rate if it is not diagnosed and treated on time.


Introducción: la aplicación de sustancias con fines estéticos de forma indiscriminada, como es el caso de la silicona en los implantes mamarios, llevan a la producción de signos locales comunes como: inflamación, irregularidad en la piel, edema, eritema, neoformaciones vasculares y úlceras, que pueden evolucionar a síntomas generales como la fiebre, astenia, adinamia, artralgias o a activar, de manera anómala, el sistema inmunitario, causando la aparición de enfermedades autoinmunitarias. A este conjunto de signos y síntomas se le denomina síndrome autoinmunitario/inflamatorio inducido por adyuvantes. Caso clínico: presentamos el caso de una mujer de 50 años con antecedente de implantes mamarios a base de silicona que desarrolla, de manera espontánea, una coagulopatía hemorrágica, se documenta hemofilia tipo A adquirida, es decir, autoanticuerpos contra el factor VIII de la coagulación. Gracias al trabajo de un equipo multidisciplinario se consigue diagnosticar y tratar de manera exitosa a la paciente con agentes de puente, remoción de los implantes y manejo de los síntomas asociados. Conclusión: se reconoce la importancia de conocer la patología que, si bien es rara, cuando se presenta tiene alta tasa de mortalidad si no se diagnostica y trata a tiempo.


Assuntos
Doenças Autoimunes , Implantes de Mama , Feminino , Humanos , Pessoa de Meia-Idade , Implantes de Mama/efeitos adversos , Síndrome , Doenças Autoimunes/diagnóstico , Doenças Autoimunes/etiologia , Inflamação/complicações , Adjuvantes Imunológicos/efeitos adversos , Silicones/efeitos adversos
13.
Eur Heart J Case Rep ; 7(4): ytad155, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37078071

RESUMO

Background: Congenital aortic diseases (CAoD) encompass a wide variety of disorders that range from asymptomatic findings to life-threatening conditions. Multiple imaging techniques are available for the assessment of CAoD. Case summary: We present seven case reports of congenital aortic diseases, including obstructions in the aortic arch (coarctation, hypoplasia, and interruption) and vascular rings, in which the clinical manifestations throughout the cases are discussed, highlighting the heterogeneity of the symptoms. Discussion: Multi-imaging techniques are indispensable for the assessment of CAoD, where cardiac computed tomography angiography is the main modality for rapid acquisition of three-dimensional volume-rendered images for optimal surgical planning.

14.
Lipids Health Dis ; 22(1): 43, 2023 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-36978188

RESUMO

BACKGROUND AND AIM: Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive metabolic disorder caused by mutations in genes involved in chylomicron metabolism. On the other hand, multifactorial chylomicronemia syndrome (MCS) is a polygenic disorder and the most frequent cause of chylomicronemia, which results from the presence of multiple genetic variants related to chylomicron metabolism, in addition to secondary factors. Indeed, the genetic determinants that predispose to MCS are the presence of a heterozygous rare variant or an accumulation of several SNPs (oligo/polygenic). However, their clinical, paraclinical, and molecular features are not well established in our country. The objective of this study was to describe the development and results of a screening program for severe hypertriglyceridemia in Colombia. METHODS: A cross-sectional study was performed. All patients aged >18 years with triglyceride levels ≥500 mg/dL from 2010 to 2020 were included. The program was developed in three stages: 1. Review of electronic records and identification of suspected cases based on laboratory findings (triglyceride levels ≥500 mg/dL); 2. Identification of suspected cases based on laboratory findings that also allowed us to exclude secondary factors; 3. Patients with FCS scores <8 were excluded. The remaining patients underwent molecular analysis. RESULTS: In total, we categorized 2415 patients as suspected clinical cases with a mean age of 53 years, of which 68% corresponded to male patients. The mean triglyceride levels were 705.37 mg/dL (standard deviation [SD] 335.9 mg/dL). After applying the FCS score, 2.4% (n = 18) of patients met the probable case definition and underwent a molecular test. Additionally, 7 patients had unique variants in the APOA5 gene (c.694 T > C; p. Ser232Pro) or in the GPIHBP1 gene (c.523G > C; p. Gly175Arg), for an apparent prevalence of familial chylomicronemia in the consulting population of 0.41 per 1.000 patients with severe HTG measurement. No previously reported pathogenic variants were detected. CONCLUSION: This study describes a screening program for the detection of severe hypertriglyceridemia. Although we identified seven patients as carriers of a variant in the APOA5 gene, we diagnosed only one patient with FCS. We believe that more programs of these characteristics should be developed in our region, given the importance of early detection of this metabolic disorder.


Assuntos
Hiperlipoproteinemia Tipo IV , Hiperlipoproteinemia Tipo I , Hipertrigliceridemia , Humanos , Masculino , Pessoa de Meia-Idade , Hiperlipoproteinemia Tipo I/diagnóstico , Hiperlipoproteinemia Tipo I/genética , Estudos Transversais , Lipase Lipoproteica/genética , Colômbia/epidemiologia , Hipertrigliceridemia/epidemiologia , Hipertrigliceridemia/genética , Hipertrigliceridemia/complicações , Triglicerídeos , Quilomícrons
15.
Oral Maxillofac Surg ; 27(1): 151-161, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35064843

RESUMO

PURPOSE: The selection of candidates for buccal fat pad (BFP) removal depends on the patient's requirements, the subjective surgeons' evaluation, and objective clinical factors. This cross-sectional observational study aimed to identify objective clinical and ultrasonographic parameters as indicators of cheek contouring with BFP excision. METHODS: Sixty-six patients with cheek fullness complaints were examined by two experienced surgeons to determine if they were good candidates for the procedure. Thereafter, participants underwent clinical and ultrasonographic assessments in a separate session to aid in the surgical decision-making. The association between the clinical judgment for BFP excision and the study variables was analyzed individually and adjusted for confounders using binary logistic regression and grouping analyses. RESULTS: Forty-nine participants were regarded as suitable and 17 as non-suitable for the procedure. After regression analysis, cheek skin-fold thickness > 6.00 mm, midfacial contour > 2.20 mm, ovoid/triangular facial form, and ultrasonographic BFP volume > 2.05 mL remained as robust individual indicators for the suitability for the procedure. However, the grouping analysis showed that patients having three-to-four significant criteria synchronously had significantly higher odds for eligibility with excellent discrimination capability. CONCLUSION: Although high values of cheek skin-fold thickness, midfacial contour, and ultrasonographic BFP volume, as well as an ovoid/triangular facial form, might be robust indicators for the suitability for BFP excision, the surgical decision-making should not be based on isolated parameters. Instead, those patients possessing a combination of at least three of these specific eligibility criteria above the threshold value might be considered the best candidates for the procedure.


Assuntos
Tecido Adiposo , Estética Dentária , Humanos , Tecido Adiposo/cirurgia , Estudos Transversais , Face , Bochecha/diagnóstico por imagem , Bochecha/cirurgia
16.
In. Rigol Ricardo, Orlando; Santisteban Alba, Stalina Rafaela. Obstetricia y ginecología. 4ta ed. La Habana, Editorial Ciencias Médicas, 4 ed; 2023. , ilus.
Monografia em Espanhol | CUMED | ID: cum-78843
17.
In. Rigol Ricardo, Orlando; Santisteban Alba, Stalina Rafaela. Obstetricia y ginecología. 4ta ed. La Habana, Editorial Ciencias Médicas, 4 ed; 2023. , ilus.
Monografia em Espanhol | CUMED | ID: cum-78829
18.
JACC Case Rep ; 4(22): 1504-1508, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36444188

RESUMO

Gaucher type 3C disease with porcelain aorta can cause severe hemodynamic impairment. We report the first case, to our knowledge, of a 13-year-old Mexican girl with a GBA1 homozygous c.1342G>C [p.Asp448His] (commonly known as p.D409H) pathogenic variant who underwent extensive aortic replacement. She has been on enzyme replacement therapy and is alive 5 years after surgery. (Level of Difficulty: Intermediate.).

19.
Langmuir ; 38(48): 14540-14549, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36399119

RESUMO

We implement molecular dynamics (MD) simulations to explore the relaxation mechanisms involved in the description of translational diffusion and rotational dynamics in water/hydrocarbon interfaces. The analysis of density profiles, self-diffusion coefficients, and nuclear magnetic resonance (NMR) relaxation properties as a function of the confinement layer width and type of hydrocarbons improves the understanding of confined water properties at water/oil interfaces. Density profile fluctuations reveal the presence of water-oil interactions close to the interface. MD results show that self-diffusion coefficients and NMR relaxation times of planar and cylindrical water/oil interfaces are strongly influenced by layer thickness and geometry. Shorter (between 20 and 60%) self-diffusion coefficients and 1H NMR relaxation times were obtained for water/n-pentane, water/n-decane, and water/n-hexadecane systems than bulk diffusion coefficients. An increase in Larmor frequency from 2.3 MHz to 400 MHz shows that longitudinal relaxation time (T1) of confined oil has slightly larger differences at higher frequencies than the transverse relaxation time (T2). At 400 MHz, n-alkanes (n-pentane, n-decane, and n-hexadecane) exhibit longer relaxation times than at smaller frequency values (2.3 and 22 MHz). Analysis of spin-spin and spin-lattice times provides relevant information about inter- and intramolecular relaxation mechanisms of water and oil as a function of geometry and width of the interface layer. These MD results suggest that the strength of confinement and geometry play a vital role in the diffusion and NMR relaxation properties of water/oil interfaces.

20.
Chem Sci ; 13(37): 11038-11047, 2022 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-36320468

RESUMO

The stabilization of uranyl(v) (UO2 1 + ) by Fe(ii) in natural systems remains an open question in uranium chemistry. Stabilization of UVO2 1+ by Fe(ii) against disproportionation was also demonstrated in molecular complexes. However, the relation between the Fe(ii) induced stability and the change of the bonding properties have not been elucidated up to date. We demonstrate that U(v) - oaxial bond covalency decreases upon binding to Fe(ii) inducing redirection of electron density from the U(v) - oaxial bond towards the U(v) - equatorial bonds thereby increasing bond covalency. Our results indicate that such increased covalent interaction of U(v) with the equatorial ligands resulting from iron binding lead to higher stability of uranyl(v). For the first time a combination of U M4,5 high energy resolution X-ray absorption near edge structure (HR-XANES) and valence band resonant inelastic X-ray scattering (VB-RIXS) and ab initio multireference CASSCF and DFT based computations were applied to establish the electronic structure of iron-bound uranyl(v).

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