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1.
Front Plant Sci ; 15: 1390461, 2024.
Article En | MEDLINE | ID: mdl-38863548

Introduction: The WD40 gene family, prevalent in eukaryotes, assumes diverse roles in cellular processes. Spartina alterniflora, a halophyte with exceptional salt tolerance, flood tolerance, reproduction, and diffusion ability, offers great potential for industrial applications and crop breeding analysis. The exploration of growth and development-related genes in this species offers immense potential for enhancing crop yield and environmental adaptability, particularly in industrialized plantations. However, the understanding of their role in regulating plant growth and development remains limited. Methods: In this study, we conducted a comprehensive analysis of WD40 genes in S. alterniflora at the whole-genome level, delving into their characteristics such as physicochemical properties, phylogenetic relationships, gene architecture, and expression patterns. Additionally, we cloned the TTG1 gene, a gene in plant growth and development across diverse species. Results: We identified a total of 582 WD40 proteins in the S. alterniflora genome, exhibiting an uneven distribution across chromosomes. Through phylogenetic analysis, we categorized the 582 SaWD40 proteins into 12 distinct clades. Examining the duplication patterns of SaWD40 genes, we observed a predominant role of segmental duplication in their expansion. A substantial proportion of SaWD40 gene duplication pairs underwent purifying selection through evolution. To explore the functional aspects, we selected SaTTG1, a homolog of Arabidopsis TTG1, for overexpression in Arabidopsis. Subcellular localization analysis revealed that the SaTTG1 protein localized in the nucleus and plasma membrane, exhibiting transcriptional activation in yeast cells. The overexpression of SaTTG1 in Arabidopsis resulted in early flowering and increased seed size. Discussion: These outcomes significantly contribute to our understanding of WD40 gene functions in halophyte species. The findings not only serve as a valuable foundation for further investigations into WD40 genes in halophyte but also offer insights into the molecular mechanisms governing plant development, offering potential avenues in molecular breeding.

2.
Neuroreport ; 35(3): 200-207, 2024 Feb 07.
Article En | MEDLINE | ID: mdl-38305107

Brain injury in preterm infants is a major cause of disability and mortality in children. GSK-3ß is a common pathogenic factor for cognitive dysfunction and involves in neuronal proliferation and differentiation. However, GSK-3ß affected neuronal differentiation and its molecular pathogenesis after hypoxic-ischemic brain damage in neonatal rats remains unclear. This study investigated the effects of GSK-3ß inhibitor (TWS119) on cell cycle regulatory proteins, a neuronal differentiation factor (CEND1), maturation neurons, T-box brain transcription factor 1 (TBR1)-positive neurons to clarify the mechanisms of hypoxic-ischemic brain damage in neonatal rats. We used hypoxic-ischemic Sprague-Dawley neonatal rats with brain damage as models. These rats were used for investigating the effect of GSK-3ß on cell cycle regulatory proteins, neuronal differentiation factor (CEND1), maturation neurons, TBR1-positive neurons by western blot and immunofluorescence. Cyclin D1 (a positive cell cycle regulator) expression decreased, and p21 (a negative cell cycle regulator) expression increased in the TWS119 group compared to the hypoxia-ischemia (HI) group 7 days after HI. Additionally, compared to the HI group, TWS119 treatment up-regulated CEND1 expression and promoted neuronal differentiation and cortex development based on NeuN and TBR1 expression. Our study suggests that the GSK-3ß inhibitor TWS119 promotes neuronal differentiation after hypoxic-ischemic brain damage in neonatal rats by inhibiting cell cycle pathway.


Hypoxia-Ischemia, Brain , Neurogenesis , Pyrimidines , Pyrroles , Animals , Rats , Animals, Newborn , Cell Cycle Proteins/metabolism , Glycogen Synthase Kinase 3 beta/metabolism , Hypoxia-Ischemia, Brain/drug therapy , Pyrimidines/pharmacology , Pyrimidines/therapeutic use , Pyrroles/pharmacology , Pyrroles/therapeutic use , Rats, Sprague-Dawley , Neurogenesis/drug effects , Neurons/cytology , Neurons/drug effects
3.
Article En | MEDLINE | ID: mdl-38228382

OBJECTIVE: To compare the efficacy and safety of non-invasive high-frequency oscillatory ventilation (NHFOV) and nasal continuous positive airway pressure (NCPAP) in preterm infants. DESIGN: The study conducted a comprehensive analysis across three databases, namely EMBASE, MEDLINE and Cochrane Central, to identify randomised controlled trials comparing NHFOV and NCPAP. Statistical analysis was performed using Review Manager V.5.3 software. MAIN OUTCOMES MEASURES: The primary outcomes of the study were the intubation or reintubation rate in the NHFOV and NCPAP groups. Additionally, secondary outcomes included the partial pressure of carbon dioxide levels and major complications associated with non-invasive respiratory support ventilation. RESULTS: Ten randomised controlled studies, involving 2031 preterm infants, were included in this meta-analysis. When compared with NCPAP, NHFOV demonstrated a significant reduction in the intubation or reintubation rate (p<0.01, relative risk=0.45, 95% CI 0.37 to 0.55), and there was no statistical difference in related complications. CONCLUSION: In preterm infants, NHFOV appears to be an effective intervention for decreasing the intubation or reintubation rate compared with NCPAP, with no increase in associated complications. TRIAL REGISTRATION NUMBER: CRD42023403968.

4.
BMJ Paediatr Open ; 7(1)2023 06.
Article En | MEDLINE | ID: mdl-37369561

BACKGROUND: Haemodynamic instability and hypoxaemia are common and serious threats to the survival of neonates. A growing body of literature indicates that critical care ultrasound has become the optimal evaluation tool for sick neonates. However, few studies have described sonographic characteristics of haemodynamics systematically in the neonates with critical illness. This protocol describes a prospective observational cohort study aimed at (1) characterising the sonographic characteristics of the neonates with critical diseases; and (2) assessing the mortality, significant morbidity, utility of vasoactive medications, fluid resuscitation, duration of ventilation, etc. METHODS AND ANALYSIS: This is a single-centre, prospective and observational study conducted in Chengdu Women's and Children's Central Hospital from 1 December 2022 to 31 December 2027. Neonates admitted to the neonatal intensive care unit will be recruited. After inclusion, the neonates will undergo the neonatal critical care ultrasound. The data collected via case report forms include clinical variables and sonographic measures. The primary outcome is to identify the sonographic characteristics of sick neonates with different diseases, and the secondary outcome is to describe the mortality, significant morbidity, utility of vasoactive medications, fluid resuscitation and duration of ventilation. DISCUSSION: Our study provided an organised neonatal critical care ultrasound workflow, which can be applied in practice. Accordingly, this study will first set up large data on the sonographic description of the neonates with critical illness, which can help to understand the pathophysiology of the critical illness, potentially titrating the treatment. TRIAL REGISTRATION NUMBER: Chinese Clinical Trial Registry (ChiCTR2200065581; https://www.chictr.org.cn/com/25/showproj.aspx?proj=184095).


Critical Illness , Intensive Care Units, Neonatal , Infant, Newborn , Child , Humans , Female , Prospective Studies , Critical Illness/therapy , Cohort Studies , Critical Care , Observational Studies as Topic
5.
Pediatr Pulmonol ; 58(3): 704-711, 2023 03.
Article En | MEDLINE | ID: mdl-36372443

OBJECTIVE: We aimed to explore whether noninvasive high-frequency oscillatory ventilation (NHFOV) could reduce the incidence of reintubation compared with nasal intermittent positive pressure ventilation (NIPPV) in the postextubation phase of preterm infants. METHODS: Randomized controlled trials of NHFOV versus NIPPV were searched in PubMed, EMBASE, Cochrane Central, and MEDLINE. Meta-analysis was performed using Review Manager 5.3. RESULTS: Four randomized controlled trials including 1138 preterm infants were included in this study. Compared with NIPPV, NHFOV reduced the incidence of reintubation in the post-extubation phase of preterm infants (p = 0.01, RR = 0.72, 95% confidence interval (CI): 0.56∼0.94), and no heterogeneity was found in the four studies (p = 0.55, I2 = 0%). In the sensitivity analysis, the result showed that there was no significant difference in the incidence of reintubation between NHFOV and NIPPV after excluding one study (p = 0. 05, RR = 0.76 95% CI: 0.58∼1.00), and no heterogeneity was found in the other three studies (p = 0.95, I2 = 0%). There was no statistical difference between NHFOV and NIPPV in BPD, air leak, IVH (≥Grade III) and mortality. CONCLUSION: Among mechanically ventilated preterm infants, compared with NIPPV, NHFOV was potentially beneficial to reduce the incidence of reintubation after extubation and did not increase the risk of complications.


High-Frequency Ventilation , Noninvasive Ventilation , Respiratory Distress Syndrome, Newborn , Infant , Infant, Newborn , Humans , Intermittent Positive-Pressure Ventilation , Infant, Premature , Airway Extubation , Intubation, Intratracheal , Continuous Positive Airway Pressure , Respiratory Distress Syndrome, Newborn/therapy , Randomized Controlled Trials as Topic
6.
Stem Cell Res Ther ; 13(1): 458, 2022 09 05.
Article En | MEDLINE | ID: mdl-36064459

Perinatal brain injury is a leading cause of death and disability in children. Hypoxic-ischemic encephalopathy in full term infants, and white matter injury in premature infants are most known brain injury in perinatal period. Human umbilical cord blood mononuclear cells contain hematopoietic stem cells, mesenchymal stem cells, endothelial progenitor cells, lymphocytes, monocytes, and so on. Human umbilical cord blood mononuclear cells have many biological functions, such as nerve and vascular regeneration, anti-apoptosis, anti-inflammation, and immune regulation. Human umbilical cord blood mononuclear cells transplantation has achieved significant efficacy and safety in animal and clinical trials for the treatment of perinatal brain injury. We will review human umbilical cord blood mononuclear cells transplantation for perinatal brain injury in this review.


Brain Injuries , Cord Blood Stem Cell Transplantation , Hypoxia-Ischemia, Brain , Animals , Brain Injuries/therapy , Child , Fetal Blood , Humans , Infant , Umbilical Cord
7.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 30(3): 890-896, 2022 Jun.
Article Zh | MEDLINE | ID: mdl-35680823

OBJECTIVE: To investigate the anti-oxidative effect of ethyl pyruvate (EP) and taurine (TAU) on the quality of red blood cells stored at 4±2 ℃, hemolysis, energy metabolism and lipid peroxidation of the red blood cells in the preservation solution were studied at different intervals. METHODS: At 4±2 ℃, the deleukocyte red blood cells were stored in the citrate-phosphate-dextrosesaline-adenine-1 (CPDA-1) preservation (control group), preservation solution with EP (EP-AS), and TAU (TAU-AS) for long-term preservation. The enzyme-linked immunoassay and automatic blood cell analyzer were used to detect hemolysis and erythrocyte parameters. Adenine nucleoside triphosphate (ATP), glycerol 2,3-diphosphate (2,3-DPG) and malondialdehyde (MDA) kits were used to test the ATP, 2,3-DPG and MDA concentration. RESULTS: During the preservation, the rate of red blood cell hemolysis in EP-AS and TAU-AS groups were significantly lower than that in CPDA-1 group (P<0.01). The MCV of EP-AS group was increased with the preservation time (r=0.71), while the MCV of the TAU-AS group was significantly lower than that in the other two groups (P<0.05). The concentration of ATP and MDA in EP-AS and TAU-AS groups were significantly higher than that in CPDA-1 group at the 14th day (P<0.01). The concentrations of 2,3-DPG in the EP-AS and TAU-AS groups were significantly higher than that in the CPDA-1 group from the 7th day (P<0.01). CONCLUSION: EP and TAU can significantly reduce the red blood cell hemolysis rate, inhibit the lipid peroxidation level of red blood cells, and improve the energy metabolism of red blood cells during storage. The mechanism of EP and TAU may be related to their antioxidation and membrane protection effect, so as to improve the red blood cell quality and extend the preservation time.


Blood Preservation , Hemolysis , 2,3-Diphosphoglycerate/metabolism , Adenine , Adenosine Triphosphate/metabolism , Citrates/metabolism , Citrates/pharmacology , Erythrocytes/metabolism , Glucose/metabolism , Glucose/pharmacology , Humans , Pyruvates , Taurine/metabolism , Taurine/pharmacology
8.
Contemp Clin Trials ; 103: 106337, 2021 04.
Article En | MEDLINE | ID: mdl-33662589

Preterm infants constitute an important proportion of neonatal deaths and various complications, and very preterm infants (VPI) are more likely to develop severe complications, such as intraventricular hemorrhage (IVH), anemia, and sepsis. It has been confirmed that placental transfusion can supplement blood volume in infants and reduce preterm-associated complications, which is further conducive to the development of the nervous system and a better long-term prognosis. Based on these advantages, placental transfusion has been widely used in VPI. There are three main types of placental transfusion: delayed cord clamping (DCC), intact umbilical cord milking (I-UCM), and cut umbilical cord milking (C-UCM). However, the optimal method for PT-VPI remains controversial, and it is urgent to identify the best method of placental transfusion. We plan to fully evaluate the safety and effectiveness of these three placental transfusion methods in VPI in a 3-arm multicenter randomized controlled trial: Placental Transfusion in Very Preterm Infants (PT-VPI). Trial registration: chictr.org.cn, number ChiCTR2000030953.


Infant, Premature , Placenta , Blood Transfusion , Constriction , Female , Humans , Infant, Newborn , Pregnancy , Umbilical Cord
9.
Front Cell Neurosci ; 15: 638351, 2021.
Article En | MEDLINE | ID: mdl-33679329

Brain microvascular endothelial cells (BMECs) are a major component of the blood-brain barrier that maintains brain homeostasis. Preserving and restoring the normal biological functions of BMECs can reverse or reduce brain injury. Endothelial progenitor cells (EPCs) may promote brain vascular remodeling and restore normal endothelial function. As a novel vehicle for cell-cell communication, microvesicles (MVs) have varied biological functions. The present study investigated the biological effects of EPC-derived MVs (EPC-MVs) on BMECs in vitro. We isolated MVs from the supernatant of EPCs in a serum-depleted medium. BMECs were cultured alone or in the presence of EPC-MVs. BMEC viability and proliferation were evaluated with the Cell Counting Kit-8 and by flow cytometry, and the proangiogenic effect of EPC-MVs on BMECs was assessed with the transwell migration, wound healing, and tube formation assays. Our results showed that EPC-derived MVs labeled with DiI were internalized by cultured BMECs; this enhanced BMEC viability and promoted their proliferation. EPC-MVs also stimulated migration and tube formation in BMECs. These results demonstrate that EPC-derived MVs exert a proangiogenic effect on BMECs, which has potential applications in cell-free therapy for brain injury.

10.
Transl Pediatr ; 10(11): 3023-3033, 2021 Nov.
Article En | MEDLINE | ID: mdl-34976768

BACKGROUND: A meta-analysis was performed to study the effect of steroid intervention on the neurodevelopment of extremely low birth weight preterm infants complicated with bronchopulmonary dysplasia, and to provide a theoretical basis for clinical treatment. METHODS: The Wanfang database, Chinese Biomedical Literature database, VIP database, Baidu Academic, CNKI database, The Cochrane Library, Medline, Embase, and PubMed database were searched by computer from establishment to 2021. Randomized controlled trials on the effect of steroids on neurodevelopment in very low birth weight preterm infants with bronchial dysplasia published from January 10, 2007 were retrieved. The included literature was evaluated for bias risk, then analyzed using RevMan 5.3 software. RESULTS: A total of 9 studies were included, with a total of 2,453 patients. The funnel plot showed that the circles and the midline of some studies were basically symmetrical, and there was no bias in the publications. The conclusions obtained were relatively reliable. Cerebral palsy, neurodevelopmental indicators, and MRI findings of preterm infants were analyzed. The cognitive impairment of very low birth weight preterm infants complicated with bronchial dysplasia (RR =0.83, 95% CI: 0.72-0.96, P=0.01) in the treatment group was significantly different from that in the control group, while cerebral palsy (RR =0.99, 95% CI: 0.75-1.29, P=0.93), speech impairment (RR =0.75, 95% CI: 0.46-1.21, P=0.24), hearing loss requiring amplification (RR =0.60, 95% CI: 0.35-1.03, P=0.06), bilateral blindness RR =0.81, 95% CI: 0.52-1.24, P=0.32), severe intraventricular hemorrhage (IVH) (RR =0.71, 95% CI: 0.33-1.50, P=0.37), and cystic periventricular leukomalacia (RR =0.82, 95% CI: 0.43-1.57, P=0.56) had no significant differences compared with the control group. DISCUSSION: In this meta-analysis, we found that the use of steroids in very low birth weight preterm infants complicated with bronchial dysplasia had significant effects on cognition, but no significant effects on hearing, vision, or language function.

11.
Trials ; 21(1): 762, 2020 Sep 03.
Article En | MEDLINE | ID: mdl-32883333

BACKGROUND: Bronchopulmonary dysplasia (BPD) is still a common complication in very premature infants. At present, there is no effective treatment for BPD. Glucocorticoids are drugs commonly used to prevent or treat BPD before and after birth. In very premature infants with high risk factors for BPD, early use of dexamethasone can reduce the rate of death and/or BPD but may cause long-term adverse neurodevelopmental outcomes. Hydrocortisone (HC), as an alternative drug to dexamethasone, has been increasingly used to prevent BPD. However, no study has reported the efficacy and safety of HC to treat early BPD diagnosed at postnatal day (PND) 28. METHODS: This study protocol is for a multicenter double-blind randomized controlled trial of low-dose HC in the treatment of early BPD. Early BPD infants will be randomly assigned to the HC treatment group or control group. Infants in the HC group will receive 0.5 mg/kg HC twice a day for 7 days and then 0.5 mg/kg HC once a day for 3 days. The control group will be given the same volume of placebo and no intervention on the basis of routine treatment. The primary outcome is survival without moderate or severe BPD at 36 weeks postmenstrual age. Secondary outcomes are the short- and long-term effects on growth, metabolism, neurodevelopment, and other possible complications. DISCUSSION: This trial will determine the efficacy and safety of low-dose HC administration compared to placebo for the reduction of moderate or severe BPD at 36 weeks postmenstrual age in very preterm infants with early BPD. TRIAL REGISTRATION: China Clinical Trial Registration Center ChiCTR1900021854 . Registered on 13 March 2019.


Bronchopulmonary Dysplasia , Hydrocortisone , Bronchopulmonary Dysplasia/diagnosis , Bronchopulmonary Dysplasia/drug therapy , Bronchopulmonary Dysplasia/prevention & control , China , Humans , Hydrocortisone/adverse effects , Infant , Infant, Newborn , Infant, Premature , Infant, Very Low Birth Weight , Multicenter Studies as Topic , Randomized Controlled Trials as Topic
12.
Transl Pediatr ; 9(2): 93-100, 2020 Apr.
Article En | MEDLINE | ID: mdl-32477908

BACKGROUND: The purpose of this study was to investigate the association between ultrasound findings and preterm infants with bronchopulmonary dysplasia (BPD). METHODS: Preterm infants with a gestation age of less than 28 weeks or birthweight less than 1,500 g admitted to the neonatal intensive care unit (NICU) in the Chengdu Women's & Children's Central Hospital from June 2018 to June 2019 were enrolled in the study and divided into 2 groups: the BPD group and the non-BPD group. All clinical data and lung ultrasound were retrospectively analyzed. RESULTS: A total of 81 neonates (gestational age =29.71±2.27 weeks; birth weight =1,189.5±184.5 g) were enrolled in our center. The regression analysis showed that gestational age [odds ratio (OR) =0.57; 95% confidence interval (CI): 0.42-0.77, P=0.0002], birthweight (OR =0.99; 95% CI: 0.99-1.00, P<0.0001), mild asphyxia (OR =3.3; 95% CI: 1.24-8.74, P=0.0165), anemia (OR =4.43; 95% CI: 1.34-14.64, P=0.0146), blood transfusion (OR =3.68; 95% CI: 1.38-9.79, P=0.0090), respiratory failure (OR =6.58; 95% CI: 1.27-34.08, P=0.0486), heart failure (OR =6.58; 95% CI: 1.27-34.08, P=0.0248), and "debris" lung ultrasound findings (OR =21.82; 95% CI: 2.63-181.11, P=0.0043) were correlated with BPD. CONCLUSIONS: BPD-related lung ultrasound findings can be a kind of imaging marker to diagnose BPD.

13.
Zhongguo Dang Dai Er Ke Za Zhi ; 20(6): 444-448, 2018 Jun.
Article Zh | MEDLINE | ID: mdl-29972116

OBJECTIVE: To study the value of bedside lung ultrasound in the diagnosis of neonatal pneumonia. METHODS: A total of 49 neonates who were admitted to the Neonatal Intensive Care Unit of Chengdu Women and Children's Central Hospital in March 2017 with respiratory symptoms as the chief complaint were enrolled. Bedside lung ultrasound was performed within 24 hours after admission. A retrospective analysis was performed for their clinical data and lung ultrasound findings. The value of bedside lung ultrasound in the diagnosis of neonatal pneumonia was evaluated. RESULTS: According to the gold standard for the diagnosis of neonatal pneumonia, of all 49 neonates, 44 were diagnosed with pneumonia. According to the criteria for the diagnosis of neonatal pneumonia based on lung ultrasound findings, 38 neonates were diagnosed with pneumonia. In the neonates with respiratory symptoms, lung ultrasound had a sensitivity of 86%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 45% in the diagnosis of neonatal pneumonia. Among the 44 cases of neonatal pneumonia diagnosed by the gold standard, the lung ultrasonic images showed B-lines in all 44 neonates (100%), 75% had pleural line abnormalities, 36% had patchy or local hypoechoic area in the lung, 27% had alveolar-interstitial syndrome, and 20% had air bronchogram. CONCLUSIONS: As a new diagnostic technique in clinical practice, bedside lung ultrasound has a high sensitivity and specificity for the diagnosis of neonatal pneumonia and can thus be used as a tool for the diagnosis of this disease.


Infant, Newborn, Diseases/diagnostic imaging , Pneumonia/diagnostic imaging , Ultrasonography/methods , Female , Humans , Infant , Infant, Newborn , Infant, Newborn, Diseases/diagnosis , Lung/diagnostic imaging , Male , Pneumonia/diagnosis , Retrospective Studies
14.
J Magn Reson ; 197(2): 208-12, 2009 Apr.
Article En | MEDLINE | ID: mdl-19201233

Low field (2 MHz) Nuclear Magnetic Resonance (NMR) proton spin-spin relaxation time (T(2)) distribution measurements were employed to investigate tetrahydrofuran (THF)-deuterium oxide (D(2)O) clathrate hydrate formation and dissociation processes. In particular, T(2) distributions were obtained at the point of hydrate phase transition as a function of the co-existing solid/liquid ratios. Because T(2) of the target molecules reflect the structural arrangements of the molecules surrounding them, T(2) changes of THF in D(2)O during hydrate formation and dissociation should yield insights into the hydrate mechanisms on a molecular level. This work demonstrated that such T(2) measurements could easily distinguish THF in the solid hydrate phase from THF in the coexisting liquid phase. To our knowledge, this is the first time that T(2) of guest molecules in hydrate cages has been measured using this low frequency NMR T(2) distribution technique. At this low frequency, results also proved that the technique can accurately capture the percentages of THF molecules residing in the solid and liquid phases and quantify the hydrate conversion progress. Therefore, an extension of this technique can be applied to measure hydrate kinetics. It was found that T(2) of THF in the liquid phase changed as hydrate formation/dissociation progressed, implying that the presence of solid hydrate influenced the coexisting fluid structure. The rotational activation measured from the proton response of THF in the hydrate phase was 31 KJ/mole, which agreed with values reported in the literature.


Magnetic Resonance Spectroscopy/methods , Deuterium Oxide/chemistry , Furans , Kinetics , Oxygen/chemistry , Temperature
15.
J Phys Chem B ; 110(13): 6549-52, 2006 Apr 06.
Article En | MEDLINE | ID: mdl-16570953

Because of the associated experimental difficulties, natural gas hydrate behavior in black oil is poorly understood despite its grave importance in deep-water flow assurance. Since the hydrate cannot be visually observed in black oil, traditional methods often rely on gas pressure changes to monitor hydrate formation and dissociation. Because gases have to diffuse through the liquid phase for hydrate behavior to create pressure responses, the complication of gas mass transfer is involved and hydrate behavior is only indirectly observed. This pressure monitoring technique encounters difficulties when the oil phase is too viscous, the amount of water is too small, or the gas phase is absent. In this work we employ proton nuclear magnetic resonance (NMR) spectroscopy to observe directly the liquid-to-solid conversion of the water component in black oil emulsions. The technique relies on two facts. The first, well-known, is that water becomes essentially invisible to liquid state NMR as it becomes immobile, as in hydrate or ice formation. The second, our recent finding, is that in high magnetic fields of sufficient homogeneity, it is possible to distinguish water from black oil spectrally by their chemical shifts. By following changes in the area of the water peak, the process of hydrate conversion can be measured, and, at lower temperatures, the formation of ice. Taking only seconds to accomplish, this measurement is nearly direct in contrast to conventional techniques that measure the pressure changes of the whole system and assume these changes represent formation or dissociation of hydrates - rather than simply changes in solubility. This new technique clearly can provide accurate hydrate thermodynamic data in black oils. Because the technique measures the total mobile water with rapidity, extensions should prove valuable in studying the dynamics of phase transitions in emulsions.

16.
J Phys Chem B ; 109(41): 19090-3, 2005 Oct 20.
Article En | MEDLINE | ID: mdl-16853461

Clathrate hydrates are of great importance in many aspects. However, hydrate formation and dissociation mechanisms, essential to all hydrate applications, are still not well understood due to the limitations of experimental techniques capable of providing dynamic and structural information on a molecular level. NMR has been shown to be a powerful tool to noninvasively measure molecular level dynamic information. In this work, we measured nuclear magnetic resonance (NMR) spin lattice relaxation times (T1's) of tetrahydrofuran (THF) in liquid deuterium oxide (D2O) during THF hydrate formation and dissociation. At the same time, we also used magnetic resonance imaging (MRI) to monitor hydrate formation and dissociation patterns. The results showed that solid hydrate significantly influences coexisting fluid structure. Molecular evidence of residual structure was identified. Hydrate formation and dissociation mechanisms were proposed based on the NMR/MRI observations.

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