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1.
Medicine (Baltimore) ; 103(12): e37467, 2024 Mar 22.
Article in English | MEDLINE | ID: mdl-38518020

ABSTRACT

Previous observational studies have observed a correlation between sedentary behavior and osteoporosis. However, conclusions from these studies have been contradictory. To explore the potential causal relationship between sedentary behavior and osteoporosis, we conducted a Mendelian randomization analysis. A two-sample Mendelian randomization was adopted to explore the causal relationship of leisure sedentary behavior with osteoporosis. We employed 5 methods to estimate the causal associations between leisure sedentary behavior and osteoporosis. Univariable Mendelian randomization results provided evidence for the causal relationship of the time spent on computer-use with the bone mineral density estimated by heel quantitative ultrasound (eBMD) (inverse variance weighted [IVW]: ß (95% confidence interval [CI]) - 0.150 (-0.270 to -0.031), P = .013; weighted median: ß (95%CI) - 0.195 (-0.336 to -0.055), P = .006). Similar associations were observed in the driving forearm bone mineral density (FABMD) (IVW: ß (95%CI) - 0.933 (-1.860 to -0.007), P = .048) and driving lumbar spine bone mineral density (IVW: ß (95%CI) - 0.649 (-1.175 to -0.124), P = .015). However, we did not find a significant causal relationship between the time spent on watching TV and bone mineral density. Research showed that there was a causal relationship between the time spent on computer use and driving time and eBMD, FABMD, and lumbar spine bone mineral density.


Subject(s)
Cogan Syndrome , Osteoporosis , Sedentary Behavior , Humans , Mendelian Randomization Analysis , Osteoporosis/etiology , Osteoporosis/genetics , Bone Density/genetics , Genome-Wide Association Study , Polymorphism, Single Nucleotide
2.
Aging (Albany NY) ; 16(5): 4250-4269, 2024 Feb 23.
Article in English | MEDLINE | ID: mdl-38407978

ABSTRACT

Lei's formula (LSF), a traditional Chinese herbal remedy, is recognized for its remarkable clinical effectiveness in treating osteoarthritis (OA). Despite its therapeutic potential, the exact molecular mechanisms underlying LSF's action in OA have remained enigmatic. Existing research has shed light on the role of the mTOR signaling pathway in promoting chondrocyte senescence, a central factor in OA-related cartilage degeneration. Consequently, targeting mTOR to mitigate chondrocyte senescence presents a promising avenue for OA treatment. The primary objective of this study is to establish LSF's chondroprotective potential and confirm its anti-osteoarthritic efficacy through mTOR inhibition. In vivo assessments using an OA mouse model reveal substantial articular cartilage degeneration. However, LSF serves as an effective guardian of articular cartilage, evidenced by reduced subchondral osteosclerosis, increased cartilage thickness, improved surface smoothness, decreased OARSI scores, elevated expression of cartilage anabolic markers (Col2 and Aggrecan), reduced expression of catabolic markers (Adamts5 and MMP13), increased expression of the chondrocyte hypertrophy marker (Col10), and decreased expression of chondrocyte senescence markers (P16 and P21). In vitro findings demonstrate that LSF shields chondrocytes from H2O2-induced apoptosis, inhibits senescence, enhances chondrocyte differentiation, promotes the synthesis of type II collagen and proteoglycans, and reduces cartilage degradation. Mechanistically, LSF suppresses chondrocyte senescence through the mTOR axis, orchestrating the equilibrium between chondrocyte anabolism and catabolism, ultimately leading to reduced apoptosis and decelerated OA cartilage degradation. LSF holds significant promise as a therapeutic approach for OA treatment, offering new insights into potential treatments for this prevalent age-related condition.


Subject(s)
Cartilage, Articular , Osteoarthritis , Mice , Animals , Chondrocytes/metabolism , Hydrogen Peroxide/pharmacology , Osteoarthritis/drug therapy , Osteoarthritis/metabolism , TOR Serine-Threonine Kinases/metabolism , Cartilage, Articular/metabolism
3.
Front Endocrinol (Lausanne) ; 14: 1200892, 2023.
Article in English | MEDLINE | ID: mdl-38027166

ABSTRACT

Objective: To explore the causal association between breakfast skipping and bone mineral density (BMD) through two-sample Mendelian randomisation (MR) analysis. Methods: A two-sample MR approach was adopted to explore the causal relationship of breakfast skipping with BMDs (across three skeletal sites and five age groups). Publicly available genome-wide association study summary data were used for MR analysis. We used five methods to estimate the causal associations between breakfast skipping and BMDs: inverse-variance weighting (IVW), MR-Egger, weighted median, simple mode, and weighted mode. IVW was used for the main analysis and the remaining four methods were used as supplementary analyses. The heterogeneity of the MR results was determined using IVW and MR-Egger methods. The pleiotropy of the MR results was determined using MR-Egger intercept. Furthermore, a leave-one-out test was performed to determine whether the MR results were affected by a single nucleotide polymorphism. Results: With the IVW method, we did not find any causal relationship between breakfast skipping and forearm, femoral neck, and lumbar spine BMD. Subsequently, when we included BMD data stratified by five different age groups in the analysis, the results showed that there was no apparent causal effect between breakfast skipping and age-stratified BMD. This finding was supported by all four supplementary methods (P > 0.05 for all methods). No heterogeneity or horizontal pleiotropy was detected in any of the analyses (P > 0.05). The leave-one-out tests conducted in the analyses did not identify any single nucleotide polymorphism that could have influenced the MR results, indicating the reliability of our findings. Conclusion: No causal effect was found between breakfast skipping and BMD (across three skeletal sites and five age groups).


Subject(s)
Bone Density , Breakfast , Bone Density/genetics , Causality , Genome-Wide Association Study , Reproducibility of Results , Mendelian Randomization Analysis
4.
World J Clin Cases ; 11(29): 7061-7074, 2023 Oct 16.
Article in English | MEDLINE | ID: mdl-37946765

ABSTRACT

BACKGROUND: Gait is influenced by race, age, and diseases type. Reference values for gait are closely related to numerous health outcomes. To gain a comprehensive understanding of gait patterns, particularly in relation to race-related pathologies and disorders, it is crucial to establish reference values for gait in daily life considering sex and age. Therefore, our objective was to present sex and age-based reference values for gait in daily life, providing a valuable foundation for further research and clinical applications. AIM: To establish reference values for lower extremity joint kinematics and kinetics during gait in asymptomatic adult women and men. METHODS: Spatiotemporal, kinematics and kinetics parameters were measured in 171 healthy adults (70 males and 101 females) using the computer-aided soft tissue foot model. Full curve statistical parametric mapping was performed using independent and paired-samples t-tests. RESULTS: Compared with females, males required more time (cycle time, double-limb support time, stance time, swing time, and stride time), and the differences were statistically significant. In addition, the step and stride lengths of males were longer. Compared to males, female cadence was faster, and statures-per-second and stride-per-minute were higher. There were no statistical differences in speed and stride width between the two groups. After adjusting for height, it was observed that women walked significantly faster than men, and they also had a higher cadence. However, in terms of step length, stride length, and stride width, both genders exhibited similarities. CONCLUSION: We established reference values for gait speed and spatiotemporal gait parameters in Chinese university students. This contributes to a valuable database for gait assessment and evaluation of preventive or rehabilitative programs.

5.
Saudi Pharm J ; 31(12): 101829, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37961070

ABSTRACT

Plumula nelumbinis, a widely used traditional Chinese medicine known for its calming and nerve-soothing properties, contains essential oil as a primary component. However, research on P. nelumbinis essential oil (PNEO) is limited. This study aimed to investigate PNEO components, network target analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, and antioxidant activity of P. nelumbinis from ten different habitats. GC-MS analysis identified 14 compounds in the essential oil, with CP12 (ß-Sitosterol) having the highest concentration. Five compounds were identified for the first time in P. nelumbinis, with three of them reported for the first time in the Nelumbo. Network target analysis revealed 185 potential targets for 11 compounds and GO and KEGG enrichment analyses showed that PNEO was mainly located in the plasma membrane and could regulate a variety of molecular functions. KEGG pathway enrichment analysis revealed that the essential oil was primarily enriched in pathways related to cancer and the nervous system. PNEO demonstrated strong antioxidant activity, with N8 (Fujiannanping) showing the highest ABTS scavenging capacity and N7 (Hunanxiangtan) showing the highest DPPH radical scavenging capacity. Cell experiments showed that CP4, CP5 and CP10 had protective effects against H2O2-induced oxidative damage. The study suggests that P. nelumbinis from different regions may have slightly different pharmacological effects due to the presence of unique compounds, and further research is necessary to explore the potential therapeutic benefits of PNEO.

6.
NeuroRehabilitation ; 51(3): 527-532, 2022.
Article in English | MEDLINE | ID: mdl-36155535

ABSTRACT

BACKGROUND: The lesions besides lateral ventricle and motor recovery following rehabilitation have hardly been studied. OBJECTIVE: To explore the relationship between the size, location of infarction beside the lateral ventricle and motor recovery following rehabilitation. METHODS: A prospective cohort of 55 patients submitted to a Rehabilitation Medical Center between January 2015 and June 2019 who suffered a single cerebral infarction beside the lateral ventricle were included in the study. The size and distance between the posterior margin and the frontal-middle line (FML) of the lesion were measured. Follow-up was conducted until the recovery was no longer progressing. Barthel index and Brunstrom stages were used to evaluate the outcome (full recovery, partial recovery and poor recovery). Variance analysis and nonparametric test were used for the comparison between groups. Multivariate logistic regression analysis was used to screen the factors affecting the outcomes. The Pearson correlation coefficient was used to compare the volume of infarction, behind the FML and the outcomes. RESULTS: Among the 55 patients, the outcome was full recovery (n = 28), partial recovery (n = 13) and poor recovery (n = 14). Multivariate logistic regression analysis showed that volume and location of the infarction were significantly correlated with the outcome (p = 0.039, 0.050). The lesion volume in the full recovery patients was significantly smaller than that in the poor recovery patients (p < 0.01). The posterior edge of the lesion in the full recovery patients behind the FML was statistically significant compared with that in the poor recovery patients (p < 0.01). Spearman correlation analysis showed that the motor recovery was negative correlation to lesion volume (r = -0.508, P < 0.01) and location (r = -0.450, P < 0.01) of the infarction. CONCLUSION: The motor recovery of patients with cerebral infarction beside lateral ventricle is related to the volume and location of the lesion. The larger the volume of the lesion, and the farther the posterior margin of the lesion to the FML, the worse the motor recovery.


Subject(s)
Lateral Ventricles , Magnetic Resonance Imaging , Humans , Prospective Studies , Fluorometholone , Cerebral Infarction , Recovery of Function
7.
Curr Microbiol ; 79(8): 236, 2022 Jun 29.
Article in English | MEDLINE | ID: mdl-35767197

ABSTRACT

Quorum sensing (QS), which controls the survival and virulence of Pseudomonas aeruginosa, including the formation of biofilm, is considered to be a new target to overcome pathogens. The aim of this study was to identify new QS inhibitors against P. aeruginosa and provide potential treatments for clinical infections. In this study, 25 compounds were isolated from Plumula nelumbini. Among these compounds, C25 showed the most significant biofilm inhibition activity, reaching 44.63% at 100 µM without inhibiting bacterial growth. Furthermore, C25 showed significant inhibition activity of rhamnolipid, pyocyanin, and elastase. Further mechanistic studies have confirmed that C25 could downregulate key genes in the QS system, including lasI, lasR, lasA, lasB, and pqsR, and Molecular docking studies have shown that C25 can bind to the active sites of the LasR and PqsR receptors. The present study suggests that C25 is a promising QS inhibitor for treating P. aeruginosa infections.


Subject(s)
Pseudomonas aeruginosa , Quorum Sensing , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Biofilms , Molecular Docking Simulation , Virulence Factors/genetics
8.
J Neurosci Methods ; 360: 109268, 2021 08 01.
Article in English | MEDLINE | ID: mdl-34171313

ABSTRACT

BACKGROUND: Although the interaction between the gut microbiota and central nervous system (CNS) is well-known, the effects of gut microbiota on different brain regions remain obscure. NEW METHOD: In present study, we developed a simple and sensitive high-performance liquid chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization in positive mode (LC-APCI+-MS/MS) for simultaneous detection of 12 analytes in the rodent' brain with different housing conditions RESULTS: The results showed that male mice in XZ group had significantly higher brain levels of dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T), progesterone (P), corticosterone (CORT), aldosterone (ALD) and 11-dehydrocorticosterone (11-DHC) than those in SPF group. CORT level was higher in the left prefrontal cortex, whereas ALD and 11-DHC levels were higher in the left hypothalamus than in the right symmetrical areas in both groups. DHEA and CORT levels were highest in the striatum than in the prefrontal cortex, hippocampus, hypothalamus, regardless of the region and group (XZ and SPF). COMPARISON WITH EXISTING METHODS: These results demonstrated that the method developed in this study provides, for the first time, direct quantitation of neurosteroids in male mice brain. CONCLUSIONS: DHEA levels showed a left-lateralized pattern in the hippocampus and hypothalamus. Mice in the XZ group showed significantly elevated levels of CORT and/or its metabolites, ALD and 11-DHC in brain than mice in the SPF group. Insanitation living conditions increased more diverse gut microbiota.


Subject(s)
Gastrointestinal Microbiome , Neurosteroids , Animals , Brain , Chromatography, High Pressure Liquid , Male , Mice , Tandem Mass Spectrometry
9.
Article in English | MEDLINE | ID: mdl-33815550

ABSTRACT

BACKGROUND: Chronic gastritis (CG) is a common digestive disease with the highest morbidity among multiple digestive diseases, which seriously lowers the life quality of patients. The pathological alternations of gastric mucosa, and its possible mechanisms have been the focus of CG-related researches. Accumulative basic and clinical evidence has confirmed that ultraviolet C (UVC) is effective in relieving superficial acute infective inflammation, skin and mucous membrane injuries, and ulcers, and promoting wound healing. OBJECTIVE: This study was aimed at investigating the protective effects of UVC on gastric mucosal injury in rats stimulated with physicochemical irritants like ethanol and exploring the mechanisms underlying the protection by UVC against gastric mucosal injury and CG. METHODS: Fifty Wistar rats were randomly divided into five groups, including Group A (normal), Group B (model), Group C (omeprazole treatment), Group D (intragastric UVC irradiation for 24 s × 2 yields), and Group E (intragastric UVC irradiation for 48 s × 2 yields). Rats in Groups B-E were made CG model by physicochemical stimulations. All rats were sacrificed one week after the 22-week experiment, and gastric tissues were harvested. Histopathological examinations were performed. The activities of superoxide dismutase and catalase as well as the contents of reduced glutathione and malondialdehyde in gastric mucosal tissues were detected. Serum interleukin-6, interleukin-1beta, tumor necrosis factor-alpha, pepsin, and gastrin were measured. RESULTS: Results showed that physiochemical irritants like ethanol could be used for easily establishing a rat CG model that shared similar pathological features with human CG. Intragastric UVC irradiation could promote the repair of gastric mucosa and improve the atrophy of gastric mucosa by inhibiting the inflammatory factors, increasing the levels of pepsin and gastrin, decreasing the expression of lipid peroxide, and enhancing the activity of superoxide dismutase and catalase and the levels of reduced glutathione. UVC irradiation for 48 s × 2 yields showed the strongest protective effect. CONCLUSION: UVC irradiation could inhibit the inflammatory factors, activate the antioxidative system, and enhance the secretion of pepsin and gastrin, which promoted the repair of injured gastric mucosa and improved gastric mucosa atrophy.

10.
Front Bioeng Biotechnol ; 8: 592068, 2020.
Article in English | MEDLINE | ID: mdl-33330423

ABSTRACT

Tendon tissue injury is very common and always associated with pain, tissue swelling and even malformation if not treated on time. Traditional therapeutic strategies, such as cryotherapy, electrical therapy, ultrasound therapy and anti-inflammatory drug, are still unsatisfying. In this work, a synergistic therapy, based on the combination of celecoxib drug and pulsed electromagnetic field (PEMF) regimens, was developed for the treatment of tendon injury. This celecoxib-loaded magnetism-responsive hydrogel dressing (gelatin/Fe3O4/celecoxib) showed good biocompatibility and coordinated drug release behavior under the PEMF, which could effectively reduce the inflammatory reaction of macrophage cells with the incremental proportion of M2 macrophages at the injury site. CatWalk gait analysis further verified this synergistic effect of combination therapy for achieving the outstanding recovery of the injured tendon tissue. Thus, this magnetism-responsive hydrogel may represent a promising alternative strategy in clinics for promoting tendon healing.

11.
Mitochondrial DNA B Resour ; 5(3): 3174-3175, 2020 Aug 17.
Article in English | MEDLINE | ID: mdl-33458101

ABSTRACT

Ligusticum sinense is a popular herb in Chinese medicine. The circular double-stranded complete chloroplast genome of L. sinense was 146,342 bp in length, exhibiting a typical quadripartite structure. It contained a large single-copy region (LSC) of 91,788 bp, a small single-copy region (SSC) of 17,618 bp and two identical inverted repeat (IR) regions of 18,468 bp each. The overall nucleotide composition of chloroplast genome sequence is: A (30.8%), T (31.6%), C (19.2%), G (19.4%) and the total G + C content of 38.6%. The chloroplast genome contained 127 genes, including 83 protein-coding genes, 36 transfer RNA genes and 8 ribosomal RNA genes were annotated. The total of 15 genes duplicated in one of the IR, including 6 tRNA, 4 rRNA, and 5 protein-coding genes. The ML phylogenetic tree indicated that L. sinense is closely related to L. tenuissimum in the phylogenetic relationship.

12.
Acta Pharmacol Sin ; 41(4): 561-571, 2020 Apr.
Article in English | MEDLINE | ID: mdl-31685975

ABSTRACT

Proximal renal tubular damage is a critical process underlying diabetic kidney disease (DKD). Our previous study shows that prostaglandin E1 (PGE1) reduces the apoptosis of renal tubular cells in DKD rats. But its underlying mechanisms remain unclear. In this study we investigated the protective effects of PGE1 in DKD rats and high glucose (HG, 30 mM)-treated HK-2 proximal tubular cells. Four weeks after uninephrectomized streptozotocin-induced diabetic rats were established, the DKD rats were administered PGE1 (10 µg· kg-1· d-1, iv.) for 10 consecutive days. We showed that PGE1 administration did not change blood glucose levels, but alleviated diabetic kidney injury in the DKD rats, evidenced by markedly reduced proteinuria and renal tubular apoptosis. In the in vitro experiments, PGE1 (0.1-100 µM) significantly enhanced HG-reduced HK-2 cell viability. In HG-treated HK-2 cells, PGE1 (10 µM) significantly suppressed the c-Jun N-terminal kinase (JNK) and the mitochondrial apoptosis-related protein expressions such as Bim, Bax, caspase-3 and cleaved caspase-3; similar changes were also observed in the kidney of PGE1-treated DKD rats. By using two pharmacological tools-JNK activator anisomycin (AM) and JNK inhibitor SP600125, we revealed that PGE1 blocked HG-triggered activation of JNK/Bim pathway in HK-2 cells; JNK was an upstream regulator of Bim. In conclusion, our results demonstrate that the nephroprotective effects of PGE1 against apoptosis of proximal renal tubule in DKD rats via suppressing JNK-related Bim signaling pathway.


Subject(s)
Alprostadil/pharmacology , Apoptosis/drug effects , Diabetic Nephropathies/drug therapy , Glucose/antagonists & inhibitors , Kidney Tubules, Proximal/drug effects , Protective Agents/pharmacology , Alprostadil/administration & dosage , Animals , Bcl-2-Like Protein 11/antagonists & inhibitors , Bcl-2-Like Protein 11/metabolism , Cells, Cultured , Diabetic Nephropathies/chemically induced , Diabetic Nephropathies/pathology , Glucose/pharmacology , Humans , Injections, Intravenous , JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors , JNK Mitogen-Activated Protein Kinases/metabolism , Kidney Tubules, Proximal/metabolism , Kidney Tubules, Proximal/pathology , Male , Protective Agents/administration & dosage , Rats , Rats, Wistar , Streptozocin
13.
Data Brief ; 21: 1591-1597, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30480072

ABSTRACT

Plumula nelumbinis is widely consumed as tea for its pharmacological properties, which is related to its chemical composition, so the identification of the major compounds of P. nelumbinis is valuable. The data described in this article is supported by the research article entitled "Chemical composition of alkaloids of Plumula nelumbinis and their antioxidant activity from different habitats in China" (Tian et al., 2018). Included are the MS-MS Spectrograms of seven alkaloid standards and thirty alkaloids identified in the P. nelumbinis, which is based on ultra-performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry method. Also included are the total alkaloids content and the antioxidant activity of total alkaloid in P. nelumbinis from 13 habitats in China, which was accomplished with three different antioxidant assays.

14.
Medicine (Baltimore) ; 97(21): e10544, 2018 May.
Article in English | MEDLINE | ID: mdl-29794730

ABSTRACT

RATIONALE: In patients with pituitary thyroid hormone resistance, the ability of the pituitary gland to detect (and down-regulate) the increase of triiodothyronine is selectively impaired, while the periphery remains sensitive to triiodothyronine levels, producing symptoms of peripheral thyrotoxicity. Subsequently, there is no feedback of pituitary production of thyroid-stimulating hormone (TSH), which is responsible for this hyperthyroidism. PATIENT CONCERNS: We report a case of a 46-year-old Chinese woman diagnosed with a thyroid nodule, with normal thyroid function. She underwent conventional subtotal thyroidectomy, and replacement therapy (levothyroxine) was used for as convention. However, it was later proven that she had pituitary resistance to thyroid hormone, as supra-physiological doses of levothyroxine were required to normalize TSH levels, which resulted in peripheral thyrotoxicity. DIAGNOSES: Based on the patient's symptoms, laboratory tests results, imaging examinations, and genetic analysis (which noted a gene mutation), a diagnosis of pituitary resistance to thyroid hormones was confirmed. INTERVENTIONS: The dose of levothyroxine was adjusted periodically and ß-adrenergic blocker was used as symptomatic treatment. OUTCOMES: The outcome in the reported case has been satisfactory despite the persistence of non-suppressed TSH. LESSONS: An inappropriate level of TSH should always be evaluated. We found a new mutation (H435A) of the thyroid hormone receptor beta gene, which allowed for the establishment of a definitive diagnosis.


Subject(s)
Pituitary Diseases/genetics , Thyroid Hormone Receptors beta/genetics , Thyroid Hormone Resistance Syndrome/genetics , Thyroxine/administration & dosage , Diagnosis, Differential , Female , Humans , Hyperthyroidism/drug therapy , Hyperthyroidism/genetics , Magnetic Resonance Imaging , Middle Aged , Mutation , Pituitary Diseases/diagnosis , Pituitary Gland/physiopathology , Thyroid Hormone Resistance Syndrome/diagnosis , Thyroid Hormone Resistance Syndrome/drug therapy , Thyroid Hormones/blood , Thyroidectomy , Thyrotropin/blood
15.
J Phys Chem B ; 110(19): 9529-33, 2006 May 18.
Article in English | MEDLINE | ID: mdl-16686499

ABSTRACT

H(2)S adsorption and dissociation on the gallium-rich GaAs(001)-4 x 2 surface is investigated using hybrid density functional theory. Starting from chemisorbed H(2)S on the GaAs(001)-4 x 2 surface, two possible reaction routes have been proposed. We find that H(2)S adsorbs molecularly onto GaAs(001)-4 x 2 via the formation of a dative bond, and this process is exothermic with adsorption energy of 6.6 kcal/mol. For the first reaction route, one of the H atoms from the chemisorbed H(2)S is transferred to a second-layer As atom and the dissociated SH is inserted into the Ga-As bond with an activation barrier of 8.2 kcal/mol, which is found to be 29.3 kcal/mol more stable than the reactants. For the second case, the dissociated species may insert themselves into the Ga-Ga dimer resulting in the Ga-H-Ga and Ga-HS-Ga bridge-bonded states, which are found to be 29.8 and 22.2 kcal/mol more stable than the reactants, respectively. However, the calculations also show that the activation barrier (16.1 kcal/mol) for chemisorbed H(2)S dissociation through the second route is higher than the transfer of one H atom into a second-layer As atom. As a result, we conclude that sulfur insertion into the Ga-As bond is more kinetically favorable.

16.
J Phys Condens Matter ; 18(26): 5937-44, 2006 Jul 05.
Article in English | MEDLINE | ID: mdl-21690809

ABSTRACT

Cluster calculations employing hybrid density functional theory have been carried out to examine the initial surface reactions in atomic layer deposition (ALD) of TiN thin films on the SiO(2) surface using TiCl(4) and NH(3) as precursors. The potential energy surface (PES) of both half-reactions at different temperatures is presented. The first half-reaction between TiCl(4) with the SiO(2) surface is activated with an activation barrier of 0.78 eV and an exothermicity of 0.38 eV, suggesting that it is thermodynamically favourable. Also, the NH(3) half-reaction begins with the formation of amido complexes by the replacement of Cl atoms by NH(2), which is endothermic by 0.58 eV with a physisorbed HCl state (HCl-PS1). Formation of the amido complexes can be followed by an elimination reaction to form imido complexes, which has a relatively high activation barrier of 2.51 eV. In addition, the effect of the reaction temperature on the Cl impurity concentrations and film growth rate in the ALD process is also discussed.

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