Parental Involvement, Academic Self-Efficacy, and Depression on Academic Performance Among Chinese Students During COVID-19 Pandemic.

Objective: This study was conducted to identify the factors (especially parental involvement, academic self-efficacy, and depression) associated with academic performance among Chinese K-12 students during the COVID-19 pandemic. Methods: This cross-sectional study used data from the 2020 China Family Panel Studies (CFPS). The CFPS was conducted from July to December 2020 during the COVID-19 pandemic. A multistage probability sample proportional to size was used for the survey. The final sample consisted of 1747 K-12 students. This study used the 14-item Chinese Parental Involvement and Support Scale, the Responsibility Scale, and the 8-item Center for Epidemiologic Studies Depression Scale to measure parental involvement, academic self-efficacy, and depression, respectively. An ordered probit regression and structural equation models were employed to analyze the factors associated with academic performance. A multiple imputation technique was applied to compute missing values in selected variables. Results: We found that parental involvement and academic self-efficacy were positively associated with good academic performance. In contrast, depression was negatively associated with good academic performance. Moreover, academic stress, male, rural residency, middle school, family size, high income, online gaming daily, reading, and intelligence quotient were statistically significant predictors on academic performance. Conclusion: The empirical findings suggested that parental involvement and academic self-efficacy were positively and significantly associated with good academic performance. However, depression was negatively and significantly associated with good academic performance. These results showed that policymakers and practitioners can help improve academic success and address educational inequalities among K-12 students by implementing a series of reforms.

Public satisfaction with health system after healthcare reform in China.

BACKGROUND: The Chinese central government launched the third phase of health system reforms in 2009. After a decade since the initiation of the reform, the health system has witnessed noteworthy gains. However, there is no concurrent improvement in public satisfaction with the health system. This study analysed various factors that influence public satisfaction with the system and examined whether perceived quality of care affects public satisfaction. METHODS: A longitudinal nationally representative survey was used for this study. We used five waves of China Family Panel Studies (CFPS) survey data. The final sample consisted of 145 843 observations. A two-way fixed-effects ordered logistic model was used for the analysis. RESULTS: The results indicate that perceived good quality of care was positively associated with public satisfaction in health system regardless of rural-urban residence. Older adults and individuals with more than 3 years of college education were less likely to be satisfied with the system in rural areas. Personal income and the density of medical professionals in the geographic area tend to improve public satisfaction in rural areas. Having medical insurance coverage and fair or good self-rated health improved the probability of reporting public satisfaction in urban areas. Married people and individuals who lived in the West region were less likely to be satisfied with the health system in urban areas. CONCLUSIONS: Knowledge and skills of healthcare providers or physical quality of facilities are not sufficient in improving public satisfaction in the health system. Policymakers need to identify options to influence the important factors that affect public perception of the system. This analysis identified several policy-amenable factors to improve public perception of the health system in rural and urban China.

Review disagreements, cultural capital, and cultural discount on imported hollywood movies in China.

Within the context of mounting competition faced by Hollywood movies in the global cinema market, particularly in emerging markets, this paper examines the influence of review disagreements and cultural capital on the cultural discount of imported Hollywood blockbusters in China's movie market. Using a dataset of 652 movies from the U.S. spanning 1994-2019, we find that review disagreements between U.S. and Chinese consumers exacerbate the cultural discount on imported Hollywood movies in China. However, cultural capital, measured by the accumulated revenue of specific imported movie genres in China, effectively mitigates this discount. We also observe a reduction in the discount for movie genres with fewer language barriers. Accounting for endogeneity due to reverse causality and selection bias, we identify a significant structural break in 2012. In the post-2012 era, collaboration involving China's censorship, quota rules, and film-production laws has improved the market mechanism and cultural capital accumulation, enhancing the performance of imported Hollywood movies in China. Minority movies, characterized by being less mainstream and commercial, are more sensitive to review disagreements, while cultural capital plays a greater role in mitigating the discount for mainstream Hollywood movies. These findings have significant implications for professionals involved in the distribution and screening of Hollywood movies in China.

Predictors of Medical Care Delay or Avoidance Among Chinese Adults During the COVID-19 Pandemic.

Purpose: Medical care delay or avoidance increases morbidity and mortality risk and is costly for the national healthcare system. The objective of this study was to identify factors associated with medical care delay or avoidance among Chinese adults during the COVID-19 pandemic. Materials and Methods: A cross-sectional analysis was conducted using data from the 2020 China Family Panel Study (CFPS). The CFPS was conducted from July to December 2020 during the COVID-19 pandemic. The final sample included 4369 adults. A logistic regression model was employed to identify the factors associated with medical care delay or avoidance. Results: The empirical results indicate that regardless of rural-urban residence, older adults and adults with chronic conditions were less likely to delay or avoid medical care during the pandemic. However, individuals who had completed more than three years of college showed a higher likelihood of delaying or avoiding medical care. In urban areas, larger family sizes, greater general trust in physicians, and higher provider structural quality were associated with a decreased probability of delaying or avoiding medical care during the pandemic. In contrast, employed adults were more likely to delay or avoid medical care. In rural areas, current smokers were more likely to delay or avoid medical care during the pandemic. Conclusion: This study has identified several factors affecting medical care delay or avoidance, some of which are amenable to policy changes. Policymakers can help improve the utilization of health facilities and patient health outcomes by implementing a series of reforms.

Factors affecting academic performance of college students in China during COVID-19 pandemic: a cross-sectional analysis.

Introduction: Understanding the factors that affected academic performance of students during the COVID-19 pandemic will help design effective interventions for improving students' academic performance during emergency situations as well as during regular academic environment. This cross-sectional study aimed to identify the factors that explain academic performance of students in China during the pandemic. Methods: Data on college students from the 2020 China Family Panel Studies were used, and the final sample consisted of 728 students. Ordered probit regression models were estimated to explain students' relative performance in the semester when the in-person classes were suspended by using various student and household-related variables and characteristics. To compute missing values in selected variables, a multiple imputation technique was applied. Results: The odds of poor academic performance declined with higher Internet use for academic purposes, but Internet use for entertainment increased the probability of being in the poor academic performance. College students who spent more time studying on college work were less likely to have poor academic performance. Discussion: This study identified the factors (Internet use and study time) associated with academic performance among Chinese college students during the COVID-19 pandemic. These results can be used to design policies to improve educational outcomes and to address educational inequalities.

Two-dimensional InTeClO3: an ultrawide-bandgap material with potential application in a deep ultraviolet photodetector.

Ultrawide-bandgap semiconductors, possessing bandgaps distinctly larger than the 3.4 eV of GaN, have emerged as a promising class capable of achieving deep ultraviolet (UV) light detection. Based on first-principles calculations, we propose an unexplored two-dimensional (2D) InTeClO3 layered system with ultrawide bandgaps ranging from 4.34 eV of bulk to 4.54 eV of monolayer. Our calculations demonstrate that 2D InTeClO3 monolayer can be exfoliated from its bulk counterpart and maintain good thermal and dynamic stability at room temperature. The ultrawide bandgaps may be modulated by the small in-plane strains and layer thickness in a certain range. Furthermore, the 2D InTeClO3 monolayer shows promising electron transport behavior and strong optical absorption capacity in the deep UV range. A two-probe InTeClO3-based photodetection device has been constructed for evaluating the photocurrent. Remarkably, the effective photocurrent (5.7 A m-2 at photon energy of 4.2 eV) generation under polarized light has been observed in such a photodetector. Our results indicate that 2D InTeClO3 systems have strong photoresponse capacity in the deep UV region, accompanying the remarkable polarization sensitivity and high extinction ratio. These distinctive characteristics highlight the promising application prospects of InTeClO3 materials in the field of deep UV optoelectronics.

Realizing tunneling electroresistance effect in the Au/h-BN/In2Se3/Au vertical ferroelectric tunnel junction.

Two-dimensional (2D) ferroelectric tunnel junctions (FTJs) have great potential in the design of non-volatile memory devices due to the tunneling electroresistance (TER) effect and the fact that it is not constrained by critical thickness. Incorporation of 2D ferroelectric materials in realistic FTJs inevitably involves the contacts to the traditional three-dimensional (3D) metals. However, how to design the FTJs by combining the 2D ferroelectric materials with the 3D metals still needs to be studied. In this work, we design a vertical 3D FTJ by adopting the 3D metal Au as the left and right electrodes and the 2D ferroelectric material In2Se3 together with h-BN as the central scattering region. By density functional theory combined with the non-equilibrium Green's function (NEGF) method, we demonstrate that the h-BN intercalation with a large bandgap plays the role of good "insulator," which breaks the symmetry of the left and right electrodes. As a result, we obtain the TER ratio of about 170%, and it can be further improved to about 1200% if two layers of In2Se3 (2L-In2Se3) are adopted as the tunneling barrier layer. Our results provide another way for the design and application of ferroelectric memory devices based on 2D ferroelectric materials.

Clinical feature and genetic mutation of KBG syndrome diagnosed in neonatal period: A case report.

RATIONALE: KBG syndrome (KBGS, OMIM: 148050), a rare genetic disorder, is clinically characterized by megalodontia, short stature, skeletal abnormalities, and nervous system manifestations. In the study, we explore the clinical and genetic characteristics of one neonate suffering KBGS caused by ANKRD11 gene mutation. PATIENT CONCERNS: The proband, a female, was born prematurely at 31 + 2 weeks. There were repeated infections and abdominal distension in the first month after birth, and the platelets could not rise to normal. Head ultrasound showed intracranial brain injury and intracranial hemorrhage. DIAGNOSES: Sequencing revealed that there was a heterozygous mutation in exon 9 of the ANKRD11 gene (NM_013275.5) for the child, c.1896_1897delTA (p.H632Qfs*30), which was a de novo mutation and has not been reported. Combining clinical features and genetic results, the proband was diagnosed as KBGS. INTERVENTIONS AND OUTCOMES: The brain sonography on day 4 after birth showed brain injury and intracranial hemorrhage. Therefore, 140 mg of bovine lung surfactant was administered through endotracheal intubation in addition to ventilator-assisted ventilation. Antibiotic treatment was also given till the inflammatory indicators of the infant returned to normal levels. The following-up of 1-year-6-month showed that the language, motion and height of development is slight falling behind the children of the same age. LESSONS: This is the first case of KBGS was diagnosed in the neonatal period, which provides a reference for the child to receive timely and correct treatment.

[Clinical and genetic analysis of a very early-onset inflammatory bowel disease type 28 child with atypical clinical manifestation].

OBJECTIVE: To explore the clinical and genetic characteristics of a very early-onset inflammatory bowel disease (VEO-IBD) type 28 child with atypical clinical manifestations. METHODS: A VEO-IBD type 28 child with atypical clinical manifestations admitted to the Department of Neonatology, Children's Hospital Affiliated to Shandong University on November 5, 2021 was selected as the study subject. Clinical data of the child was collected. Peripheral venous blood samples of the child and his parents were collected for high-throughput sequencing. Candidate variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: The child, a 50-day-old male, had manifested bronchitis, ulcerative stomatitis, eczema and slightly loose stool. High-throughput sequencing revealed that he has harbored compound heterozygous variants of the IL-10RA gene, namely c.299T>G (p.V100G) and c.301C>T (p.R101W), which were inherited from his father and mother, respectively. Bioinformatic analysis showed that both variants have been recorded in the HGMD database, though the c.299T>G variant has not been included in the gnomAD, 1000 Genomes, ExAC and ESP6500 databases, while the c.301C>T variant has a low population frequency. Both variants were predicted to be deleterious by the online software including SIFT, PolyPhen-2 and Mutation Taster. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were predicted to be pathogenic (PS3+PM2_Supporting+PP3). CONCLUSION: The c.299T>G and c.301C>T variants of the IL-10RA gene probably underlay the VEO-IBD type 28 in this child. Above finding has expanded the phenotypic spectrum of VEO-IBD type 28 due to variants of the IL-10RA gene and provided a reference for the clinical diagnosis of this disease.

Tunnel electroresistance effect in a two-dimensional organic ferroelectric tunnel junction.

Two-dimensional (2D) ferroelectric materials have important application potential in device miniaturization due to their characteristics of only being a few atomic layers thick and non-volatility. How to design high-performance ferroelectric memory devices based on 2D ferroelectric materials has attracted extensive attention. In this work, based on the 2D organic ferroelectric material semi-hydroxylized graphane (SHLGA), which has in-plane ferroelectric polarization along three different directions, we construct a 2D organic ferroelectric tunnel junction (FTJ). By means of density functional theory (DFT) and the non-equilibrium Green's function (NEGF) method, we calculate the transport properties of the FTJ under different polarizations and obtain a giant tunnel electroresistance (TER) ratio of 7.55 × 104%. We find that the mechanism behind the TER effect in the organic SHLGA is based on the unique built-in electric field. That is, among the three ferroelectric polarization directions, any two directions have an angle of 120°. As a result, the built-in electric fields along the transport direction of the FTJ under different ferroelectric polarization directions are different. Moreover, our study shows that the giant TER effect can also be achieved by utilizing the asymmetry of the polarization along the transport direction of the ferroelectric material itself, which provides another route for the design of 2D FTJs.

The long-term mediation role of cytokines on the causal pathway from maternal gestational age to offspring eye diseases: Lifecourse-Network Mendelian randomization.

BACKGROUND: Gestational duration has a significant impact on eye diseases. A large number of evidences suggest that cytokines are associated with gestational duration and eye diseases. However, the causal relationships among cytokines, maternal gestational impairment and offspring eye diseases remain unclear. METHODS: We performed lifecourse-network Mendelian randomization (MR) to explore the causal relationships between maternal gestational duration (from the Early Growth Genetics (EGG) Consortium and the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) study, N = 84,689), neonatal/adult cytokines (from the NHGRI-EBI Catalog, N = 764/4,618), and adult eye diseases (from FinnGen consotium, N = 309,154) using summary-level data from large genome-wide association studies. Multiplicative random effects inverse variance weighted (IVW) and multivariable-IVW methods were the main analysis methods, and the other 15 pleiotropy-robust methods, weak IV-robust methods, and outliers-robust methods were used as auxiliary methods. RESULTS: Maternal gestational age (early preterm birth, preterm birth, gestational duration, and post-term birth) had a causal relationship with 42 eye diseases. Four neonatal cytokines, Tumor Necrosis Factor-α(TNF-α), IL10, GROA, and CTACK, as well as four adult cytokines, CTACK, IL10, IL12p70 and IL6 are mediators in the causal relationships between early preterm birth and preterm birth in eight eye diseases. However, after adjusting for these mediators, a null direct causal effect of early preterm birth and preterm birth on eight eye diseases was found. In addition, there was no mediator in the causal relationship between gestational duration and post-term birth to eye diseases. CONCLUSION: The effects of maternal gestational duration on offspring eye diseases through cytokines are long-term and life-course effects.

Cultural Distance, Classroom Silence and Culturally Responsive and Inclusive Education: Evidences from Migrant College Students in Shanghai.

This paper investigated the relationship between cultural distance, classroom silence, and the performance of culturally responsive and inclusive education (CRIE) using a survey of 1051 college students in Shanghai in 2022. We found a significantly positive association between migrant students' cultural distance and their perceived learning gains in class. Students' cultural distance increased their classroom silence as a form of protection but had no significant effect on their classroom silence as a sign of power. The classroom silence as protection decreased students' perceived learning gains. However, classroom silence as power could be used by both local and migrant students as a hold-up strategy to strengthen their influence in class discussions, which could improve their perceived learning gains. Teachers' CRIE played the most important role in migrant students' perceived learning gains, while the effectiveness of CRIE was also actually dependent on the different channels and mechanisms of cultural distance and classroom silence. A cautious identification of classroom silence will improve the effectiveness of CRIE. Suggestions are offered to lighten the practice of educators, administrators, and instructors who face classroom silence from subnational migrant students.

How the volatile organic compounds emitted by corpse plant change through flowering.

The corpse plant (Amorphophallus titanum) is so named because it produces a pungent, foul odor when flowering. Little is known about how the emitted volatiles change throughout the two-day flowering period. In this study, the comprehensive monitoring of the presence and change in volatile molecules during the female and the male flowering phases of A. titanum was conducted, and the plant temperature was monitored. A total of 422 volatile features were detected over the entire sampling period, of which 118 features were statistically significantly different between the pre-flowering and both flowering phases, and an additional 304 features were found present throughout the flowering period. A total of 45 molecules could be assigned putative names. The volatile profile of A. titanum changes over the two-day flowering period, with the S-containing molecules and aldehydes dominant in the female flowering phase, and the alcohols and hydrocarbons dominant in the male flowering phase. The two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) enabled us to identify 32 new molecules produced by A. titanum. Each of these molecules alone, and in combination, likely contribute to the different odors emitted during the flowering phase of A. titanum.

Sildenafil Improves Pulmonary Vascular Remodeling in a Rat Model of Persistent Pulmonary Hypertension of the Newborn.

ABSTRACT: Persistent pulmonary hypertension of the newborn (PPHN) is characterized by pulmonary arterial remodeling mainly because of apoptosis resistance and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs). Sildenafil is a phosphodiesterase-5 inhibitor. Some reports have shown that sildenafil exerts protective effects against PPHN. However, the function of sildenafil in PPHN and the underlying molecular mechanisms is not clear. Here, we revealed that sildenafil effectively suppressed hypoxia-induced PASMC proliferation and apoptosis inhibition ( P < 0.05). Also, sildenafil obviously reduced ventricular hypertrophy, and inhibited pulmonary vascular remodeling in the PPHN model ( P < 0.05). Moreover, sildenafil treatment significantly attenuated the induction of Notch3 and Hes1 induced by hypoxia treatment ( P < 0.05). Furthermore, overexpression of Notch3 abolished the reduction of PASMC proliferation and promotion of PASMC apoptosis induced by sildenafil under hypoxia ( P < 0.05), whereas knockdown of Notch3 had an opposite effect ( P < 0.05). Together, our study demonstrates that sildenafil shows a potential benefit against the development of PPHN by inhibiting Notch3 signaling, providing a strategy for treating PPHN in the future.

A synonymous mutation in PI4KA impacts the transcription and translation process of gene expression.

Phosphatidylinositol-4-kinase alpha (PI4KIIIα), encoded by the PI4KA gene, can synthesize phosphatidylinositol-4-phosphate (PI-4-P), which serves as a specific membrane marker and is instrumental in signal transduction. PI4KA mutations can cause autosomal recessive diseases involving neurological, intestinal, and immunological conditions (OMIM:619621, 616531, 619708). We detected sepsis, severe diarrhea, and decreased immunoglobulin levels in one neonate. Two novel compound heterozygous mutations, c.5846T>C (p.Leu1949Pro) and c.3453C>T (p.Gly1151=), were identified in the neonate from the father and the mother, respectively. Sanger sequencing and reverse transcription polymerase chain reaction (RT-PCR) for peripheral blood and minigene splicing assays showed a deletion of five bases (GTGAG) with the c.3453C>T variant at the mRNA level, which could result in a truncated protein (p.Gly1151GlyfsTer17). The missense mutation c.5846T>C (p.Leu1949Pro) kinase activity was measured, and little or no catalytic activity was detected. According to the clinical characteristics and gene mutations with functional verification, our pediatricians diagnosed the child with a combined immunodeficiency and intestinal disorder close to gastrointestinal defects and immunodeficiency syndrome 2 (GIDID2; OMIM: 619708). Medicines such as immunomodulators are prescribed to balance immune dysregulation. This study is the first report of a synonymous mutation in the PI4KA gene that influences alternative splicing. Our findings expand the mutation spectrum leading to PI4KIIIa deficiency-related diseases and provide exact information for genetic counseling.

A potential pathogenic hypoxia-related gene HK2 in necrotizing enterocolitis (NEC) of newborns.

BACKGROUND: Necrotizing enterocolitis (NEC) is a disastrous gastrointestinal disease of newborns, and the mortality rate of infants with NEC is approximately 20%-30%. The exploration of pathogenic targets of NEC will be conducive to timely diagnosis of NEC. METHODS: The whole transcriptome RNA sequencing was performed on NEC samples to reveal the expression of lncRNAs, circRNAs, miRNAs and mRNAs. Using differential expression analysis, cross analysis, target prediction, enrichment analysis, the pathogenic ceRNA network and target was found. RESULTS: Preliminarily, 281 DEmRNAs, 21 DEmiRNAs, 253 DElncRNAs and 207 DEcircRNAs were identified in NEC samples compared with controls. After target prediction and cross analyses, a key ceRNA regulatory network was built including 2 lncRNAs, 4 circRNAs, 2 miRNAs and 20 mRNAs. These 20 mRNAs were significantly enriched in many carbohydrate metabolism related pathways. After cross analysis of hypoxia-, carbohydrate metabolism-related genes, and 20 core genes, one gene HK2 was finally obtained. Dendritic cells activated were significantly differentially infiltrated and negatively correlated with HK2 expression in NEC samples. CONCLUSIONS: The promising pathogenic hypoxia-related gene HK2 has been firstly identified in NEC, which might also involve in the carbohydrate metabolism in NEC.

Tobacco smoking and depressive symptoms in Chinese middle-aged and older adults: Handling missing values in panel data with multiple imputation.

Introduction: The high co-occurrence of tobacco smoking and depression is a major public health concern during the novel coronavirus disease-2019 pandemic. However, no studies have dealt with missing values when assessing depression. Therefore, the present study aimed to examine the effect of tobacco smoking on depressive symptoms using a multiple imputation technique. Methods: This research was a longitudinal study using data from four waves of the China Health and Retirement Longitudinal Study conducted between 2011 and 2018, and the final sample consisted of 74,381 observations across all four waves of data collection. The present study employed a multiple imputation technique to deal with missing values, and a fixed effects logistic regression model was used for the analysis. Results: The results of fixed effects logistic regression showed that heavy smokers had 20% higher odds of suffering from depressive symptoms than those who never smoked. Compared to those who never smoked, for short-term and moderate-term quitters, the odds of suffering from depressive symptoms increased by 30% and 22%, respectively. The magnitudes of the odds ratios for of the variables short-term quitters, moderate-term quitters, and long-term quitters decreased in absolute terms with increasing time-gaps since quitting. The sub-group analysis for men and women found that heavy male smokers, short-term and moderate-term male quitters had higher odds of suffering from depressive symptoms than those who never smoked. However, associations between smoking status and depressive symptoms were not significant for women. Conclusions: The empirical findings suggested that among Chinese middle-aged and older adults, heavy smokers and short-term and moderate-term quitters have increased odds of suffering from depressive symptoms than those who never smoked. Moreover, former smokers reported that the probability of having depressive symptoms decreased with a longer duration since quitting. Nevertheless, the association between depressive symptoms and smoking among Chinese middle-aged and older adults is not straightforward and may vary according to gender. These results may have important implications that support the government in allocating more resources to smoking cessation programs to help middle-aged and older smokers, particularly in men.

Enhancing Resin Cement Adhesion to Zirconia by Oxygen Plasma-Aided Silicatization.

The combinations of alumina particle air abrasion (AA) and a 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) primer and a tribochemical silica coating (TSC) and a silane-base primer are contemporary pre-cementation treatments for zirconia restorations for bonding with resin cements. However, the stability of zirconia resists the mechanical or chemical preparations. The purpose of this study was to develop an atmospheric-pressure oxygen plasma (OP)-aided silicatization method to enhance the adhesion of resin cements to zirconia. Zirconia discs were prepared to receive surface treatments of different combinations: (1) AA or TSC (2) with or without OP treatment, and (3) a chemical primer (no primer, silane, or a silane-MDP mixture). The surface morphology, hydrophilicity, and chemical compositions were characterized, and the resin-zirconia bond strengths were examined either after 24 h or a thermocycling test. The results indicated that the OP treatment after the TSC facilitated the homogeneous distribution of silane and crosslinking of silica particles, and effectively improved the hydrophilicity. The OP increased the O and Si and reduced the C elemental contents, while the combination of TSC, OP, and silane induced SiOx generation. Among the groups, only the TSC-OP-silane treatment effectively enhanced the bond strength and maintained the adhesion after thermocycling. With these results, the OP aided the silicatization protocol effectively, generated silane crosslinking, and resulted in superior resin-zirconia bond strength and durability compared to the current treatments.

Interaction of silane with 10-MDP on affecting surface chemistry and resin bonding of zirconia.

OBJECTIVE: To investigate the effect of silane contents on their chemical interaction with 10-methacryloyloxydecyl-dihydrogen phosphate (MDP), and affecting the bonding of MDP to zirconia by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. METHODS: Zirconia (Cercon ht, Dentsply) slabs were prepared and fully sintered. Experimental primers SE-5 and SE-10 were formulated by adding 5 wt% and 10 wt% γ-methacryloxypropyltrimethoxysilane to an MDP-based primer SE BOND (SE), respectively. SE, SE-5, and SE-10 were applied on the assigned zirconia slabs. The chemical compositions on the surface and adhesive interfaces were examined by TOF-SIMS in a depth-profiling mode. Hydrophilicity and resin affinity of treated zirconia were analyzed. The bond strengths to resin cylinder were examined either after 24-h storage or thermocycles. In addition, zirconia powders treated with three primers were assessed by SSNMR spectrometry for the adsorption of MDP. RESULTS: TOF-SIMS analysis showed that SE treatment generated the greatest amount of P-O-Zr related ions, which reduced in SE-5 and SE-10 groups. The 3D ion-images illustrated the generation of ZrO2(OH)- ions with silane contents. The SSNMR analysis revealed that the chemical bonding was mainly P-O-Zr ionic bonds in SE but shifted to P-OH-Zr hydrogen bonds in SE-5 and SE-10. SE-5 and SE-10 treated zirconia presented higher hydrophilicity and affinity to resin compared to Zr did. SE showed the highest initial bond strength which significantly decreased after thermocycling. SIGNIFICANCE: MDP adsorption onto zirconia via P-O-Zr ionic bond promotes bonding with resin. The silane enhances the hydroxylation of zirconia and impairs the adsorption of MDP, but does not adversely affect the bond durability.

Investigations of silane-MDP interaction in universal adhesives: A ToF-SIMS analysis.

OBJECTIVES: The purposes of this study were to investigate whether the presence of silane in universal adhesives affects the functions of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and adhesion to zirconia. METHODS: Two silane-containing universal adhesives (Scotchbond Universal (SBU) and Clearfil Universal-Bond (CUB)) and two silane-free adhesives (All-Bond Universal (ABU) and SE-Bond primer (SE)) were individually applied on zirconia disks. Time-of-flight secondary-ion-mass-spectrometry (ToF-SIMS) examined the distributions of MDP- and silane-related ions, as well as evidence of zirconium phosphate (ZrP) compounds, on the surface and interfacial regions using a depth profiling mode. The hydrophilicity and resin wettability of the treated zirconia were examined using a contact angle test. For the shear bond strength (SBS) test, the zirconia disks were air-blasted, treated with the assigned adhesives, and bonded with pre-cured composite cylinders using a resin cement. These resin-zirconia assemblies received a bond test after 24-h storage. RESULTS: Both SBU and CUB exhibited silane-related ions and ZrO2(OH)-, but fewer PO- ions in the interfacial regions. CUB had more siloxane-related ions. SE-treated zirconia had abundant PO- ions and particularly high PO3-- and ZrP- related ions in the interfacial regions. The silane-free adhesives exhibited a higher affinity to both water and adhesive liquids. SE showed significantly higher SBSs compared to ABU, while SBU and CUB were not statistically different. SIGNIFICANCE: The silane content may cause hydroxylation of zirconia and affect MDP adsorption. An acidic pH accelerated the condensation of silanol. The bond performance of the MDP-based adhesive could be influenced by the silane content and other components.