Impact of crosslinking agents with steric cyclic groups on the properties of polymer-dispersed liquid crystals.

As a type of intelligent dimming film, polymer-dispersed liquid crystals (PDLCs) have been widely applied in various fields, such as smart windows, light shutters and displays. The properties of PDLCs are greatly influenced by the structure of the raw materials. In this work, the impact of crosslinking agents with different cyclic or chain groups was investigated by comparing the electro-optical performance and the morphology of the polymer matrix in the as-made PDLC films. It was found that the incorporation of large steric groups into the crosslinking agents can alter the morphology of the polymer matrix and thus affect the electro-optical properties. However, the impact is distinct when the spatial structure or rigidity is different. Besides, a combination of crosslinking agents with flexible alkyl-chain structures and steric structures can further reduce the threshold voltage while keeping the high contrast ratio. After detailed comparison, an optimized combination of BDDA/TCDDA in a weight ratio of 1/1 is selected to demonstrate the enhanced properties of the as-constructed film with a thickness of 20 µm. It exhibits low threshold voltage (8.2 V), low saturation voltage (21.2 V) and a high contrast ratio (203) simultaneously. This research offers an optimizing method from the crosslinking agent perspective and is anticipated to promote the further improvement of the PDLC's performance.

Balanced electro-optical properties and off-axis haze performance of a polymer-dispersed liquid crystal film via refractive index matching.

As a type of smart dimming film, polymer-dispersed liquid crystals (PDLCs) show great prospects in the fields of indoor partition, electronic curtains, and automobile windows. However, its high off-axis haze greatly impacts the application scope. This obvious shortcoming is mainly caused by the serious mismatch between the effective refractive index of the liquid crystal (neff) and the refractive index of the polymer matrix (np) at large viewing angles. Thereby, factors affecting the viewing angle of a PDLC film are analyzed in this research, including the birefringence of the liquid crystal (Δn), film thickness, and the refractive index of the polymer matrix (np). Balanced electro-optical properties are guaranteed simultaneously. It is found that high on-state transmittance and low off-axis haze can be achieved at large viewing angles in the suggested optimized case where Δn is within the range of 0.1-0.13; the film thickness is between 20 µm and 15 µm; and np approaches no but the difference does not exceed 0.03.

Molecular mechanism in trigeminal nerve and treatment methods related to orthodontic pain.

BACKGROUND: Orthodontic treatment is the main treatment approach for malocclusion. Orthodontic pain is an inevitable undesirable adverse reaction during orthodontic treatment. It is reported orthodontic pain has become one of the most common reason that patients withdraw from orthodontic treatment. Therefore, understanding the underlying mechanism and finding treatment of orthodontic pain are in urgent need. AIMS: This article aims to sort out the mechanisms and treatments of orthodontic pain, hoping to provide some ideas for future orthodontic pain relief. MATERIALS: Tooth movement will cause local inflammation. Certain inflammatory factors and cytokines stimulating the trigeminal nerve and further generating pain perception, as well as drugs and molecular targeted therapy blocking nerve conduction pathways, will be reviewed in this article. METHOD: We review and summaries current studies related to molecular mechanisms and treatment approaches in orthodontic pain control. RESULTS: Orthodontics pain related influencing factors and molecular mechanisms has been introduced. Commonly used clinical methods in orthodontic pain control has been evaluated. DISCUSSION: With the clarification of more molecular mechanisms, the direction of orthodontic pain treatment will shift to targeted drugs.

Finger-Temperature-Detecting Liquid Crystal Composite Film for Anti-Counterfeiting Labels.

The development of the economy has increased the demand for anti-counterfeiting technologies, and with the traditional ones becoming known to the public, new and more effective ones are needed. In this study, a series of liquid crystal mixtures containing side-chain liquid crystal polymers and small-molecular-weight liquid crystals (LCs) were designed and prepared. The phase transition behavior and self-assembling structures of the LC mixtures were investigated by a combination of differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray diffraction. The optical properties of the mixture film were characterized with a UV/VIS/IR spectrum study. The results reveal that the obtained film exhibited different optical modes between transparent, scattering, and selective reflection under finger-temperature control. Therefore, by the introduction of a coexisting thermal- or optical-polymer-dispersed network, a liquid crystal composite film with an integration of apparent optical switching modes and enhanced strength and toughness was successfully demonstrated. This research provides a versatile strategy for the design and preparation of liquid crystal anti-counterfeiting materials for practical use. In this study, a prototype finger-temperature-detecting anti-counterfeiting label was prepared, and its temperature-response property was demonstrated.

A Study on the Electro-Optical Properties of Thiol-Ene Polymer Dispersed Cholesteric Liquid Crystal (PDChLC) Films.

In this study, a polymer dispersed cholesteric liquid crystal (PDChLC) film obtained via a one-step fabrication technique based on photopolymerization of a thiol-acrylate reaction system was prepared and characterized for the first time. The effects of the chiral dopant, the influence of thiol monomer functionality and content on the morphology and subsequent performance of the PDChLC films were systematically investigated. It was demonstrated that the addition of a small amount of chiral dopant slightly increased the driving voltage, but decreased the off-state transmittance significantly. Furthermore, scanning electron micrographs (SEM) shown that the liquid crystal (LC) droplet size decreased at first and then increased with the increasing amount of thiol monomer functionality, while increasing the thiol content increased the LC droplet size. Correspondingly, the electro-optical switching behavior was directly dependent on LC droplet size. By tuning the raw material composition, PDChLC film with optimized electro-optical performance was prepared.

Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films.

Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

Orthodontic Practitioners' Knowledge and Education Demand on Clear Aligner Therapy.

OBJECTIVES: Clear aligner therapy (CAT) has been gaining popularity amongst the orthodontic community. No systematic course on CAT has been reported to date. The objectives of this study were to determine practitioners' knowledge and to offer insights for future tailored courses on CAT. METHODS: An online questionnaire was distributed. The questionnaire comprised personal background information, predictability of tooth movement through CAT, and CAT knowledge that practitioners demanded to learn. Four senior expert orthodontists' answers to the predictability of tooth movement through CAT were averaged to be a standard reference. Descriptive statistics, 1-way analysis of variance (ANOVA), principal component analysis, Student t test, and multivariate logistics regression analysis were performed with significance set at P < .05. RESULTS: In total, 190 practitioners participated in this study. As compared to the standard reference, participants overestimated the predictability of difficult-to-be-achived tooth movements (eg, molar mesialisation; P < .0001). Strategy of managing troubleshooting cases and extraction cases ranked the highest CAT knowledge that participants requested to learn. Practice type, number of completed CAT cases, number of undergoing CAT cases, years of practice, education background, and time of using CAT were the influencing factors of the questions regarding the predictability of tooth movement through CAT and CAT knowledge that were demanded to be learned. CONCLUSIONS: The predictability of difficult-to-be-achieved tooth movement through CAT is often overestimated by practitioners with limited clinical experience. Tailored education on CAT, especially managing troubleshooting cases and extraction cases, should be designed for all practitioners.

A Smart Window with Passive Radiative Cooling and Switchable Near-Infrared Light Transmittance via Molecular Engineering.

Smart windows with synergetic light modulation have heightened demands for applications in smart cars and novel buildings. However, improving the on-demand energy-saving efficiency is quite challenging due to the difficulty of modulating sunlight with a broad bandwidth in an energy-saving way. Herein, a smart window with switchable near-infrared light transmittance and passive radiative cooling is prepared via a monomer design strategy and photoinduced polymerization. The effects of hydrogen bonds and fluorine groups in acrylate monomers on the electro-optical properties as well as microstructures of polymer-dispersed liquid crystal films have been systematically studied. Some films show a high contrast ratio of 90.4 or a low threshold voltage (Vth) of 2.0 V, which can be roll-to-roll processed in a large area. Besides, the film has a superior indoor temperature regulation ability due to its passive radiative cooling and controllable near-infrared light transmittance properties. Its radiative cooling efficiency is calculated to be 142.69 W/m2 and NIR transmittance could be switched to below 10%. The introduction of a carboxylic monomer and fluorinated monomer into the system endows the film with a highly efficient temperature management capability. The film has great potential for applications in fields such as flexible smart windows, camouflage materials, and so on.

Reverse-Mode Polymer-Stabilized Liquid Crystal Films with Enhanced Peel Strength and Electro-Optical Performance Based on Photoreactive Self-Assembly Alignment Layers and Patterned Polymer Walls.

Polymer-stabilized liquid crystal (PSLC) is a promising material toward the practical application of serving as energy-saving reverse-mode smart windows owing to its superior electro-optical (E-O) properties, simple and efficient processability, and compatibility to most practical circumstances. However, its feeble peel strength originated from low polymer content and poor adhesion between polymer networks and substrates inhibited its large-scale flexible film production. It is still a challenging task to derive good mechanical properties and superior E-O performance for PSLCs at the same time. In this study, a highly durable liquid crystal/polymer composite film showing enhanced peel strength and excellent E-O properties was attained by simultaneously building photoreactive self-assemble alignment layers through an efficient one-step method and the sculpture of a patterned polymer wall structure. This film has comprehensive ascendant E-O properties of lower driving voltages, faster response times, and higher contrast ratio, together with an over 30 times lift of the peel strength. The effectuation mechanisms of the alignment, E-O properties, peel-strength, microstructures, and cyclic durability of the films have been systematically studied. This novel liquid crystal/polymer composite film demonstrates advantages in every aspect of performance compared to traditional PSLC devices, which hoards promising applications in smart windows for cars and buildings.

Study on the Polymer Morphology and Electro-Optical Performance of Acrylate/Epoxy Resin-Based Polymer-Stabilized Liquid Crystals Based on Stepwise Photopolymerization.

Stepwise photopolymerization is a miraculous strategy modulating the polymer skeleton and electro-optical properties of light modulators based on liquid crystal/polymer composites. However, owing to the indistinct polymerization mechanism and curing condition discrepancy, the required polymer structures and electro-optical properties are hard to be controlled precisely. Herein, a novel polymer-stabilized liquid crystal film based on acrylate/epoxy resin is proposed, fabricated and the relationships between preparation process, polymer content, polymer morphology and electro-optical properties are studied. The in-situ photopolymerization of acrylate/epoxy resin liquid crystalline polymer is fulfilled using cation photo-initiator UV 6976. The distinct photopolymerization speed between acrylate and epoxy resin benefits the polymer morphology control, and with accurate containment of the polymerization process and polymer composition, the superior electro-optical properties at a higher polymer content are acquired. The polymer morphology and electro-optical properties are influenced by the polymer content and mass ratio between acrylate and epoxy resin. The best electro-optical properties among samples are attained by controlling the mass ratio between acrylate and epoxy resin to 1:1, integrating higher densities of scattering centers and lower anchoring effect. With higher polymer content, the strategy of increasing the mass ratio of E6M benefits the improvement of E-O properties for alleviating polymer density. This work provides insights to stepwise polymerization of liquid crystalline monomers and offers a fancy strategy for the preparation of novel liquid crystal dimming films.

The EDA/EDAR/NF-κB pathway in non-syndromic tooth agenesis: A genetic perspective.

Non-syndromic tooth agenesis (NSTA) is one of the most common dental developmental malformations affected by genetic factors predominantly. Among all 36 candidate genes reported in NSTA individuals, EDA, EDAR, and EDARADD play essential roles in ectodermal organ development. As members of the EDA/EDAR/NF-κB signaling pathway, mutations in these genes have been implicated in the pathogenesis of NSTA, as well as hypohidrotic ectodermal dysplasia (HED), a rare genetic disorder that affects multiple ectodermal structures, including teeth. This review provides an overview of the current knowledge on the genetic basis of NSTA, with a focus on the pathogenic effects of the EDA/EDAR/NF-κB signaling pathway and the role of EDA, EDAR, and EDARADD mutations in developmental tooth defects. We also discuss the phenotypic overlap and genetic differences between NSTA and HED. Ultimately, this review highlights the importance of genetic analysis in diagnosing and managing NSTA and related ectodermal disorders, and the need for ongoing research to improve our understanding of these conditions.

A new stock market analysis method based on evidential reasoning and hierarchical belief rule base to support investment decision making.

Stock market analysis is helpful for investors to make reasonable decisions and maintain market stability, and it usually involves not only quantitative data but also qualitative information, so the analysis method needs to have the ability to deal with both types of information comprehensively. In addition, due to the inherent risk of stock investment, it is necessary to ensure that the analysis results can be traced and interpreted. To solve the above problems, a stock market analysis method based on evidential reasoning (ER) and hierarchical belief rule base (HBRB) is proposed in this paper. First, an evaluation model is constructed based on expert knowledge and ER to evaluate stock market sentiment. Then, a stock market decision model based on HBRB is constructed to support investment decision making, such as buying and selling stocks and holding positions. Finally, the Shanghai Stock Index from 2010 to 2019 is used as an example to verify the applicability and effectiveness of the proposed stock market analysis method for investment decision support. Experimental research demonstrates that the proposed method can help analyze the stock market comprehensively and support investors to make investment decisions effectively.

Effectiveness of clear aligners in achieving proclination and intrusion of incisors among Class II division 2 patients: a multivariate analysis.

BACKGROUND: The predictability of incisor movement achieved by clear aligners among Class II division 2 patients is poorly understood. The aim of this retrospective study was to determine the effectiveness of clear aligners in proclining and intruding upper incisors and its influencing factors. METHODS: Eligible patients with Class II division 2 malocclusion were included. For clear aligner therapy, three types of incisor movements were designed: proclination, intrusion and labial movement. Pre-treatment and post-treatment dental models were superimposed. The differences between predicted and actual (DPA) tooth movement of incisors were analyzed. Univariate and multivariate linear regression were used to analyze the potential influencing factors. RESULTS: A total of 51 patients and their 173 upper incisors were included. Actual incisor proclination and intrusion were less than predicted ones (both P < 0.001), while actual labial movement was greater than predicted one (P < 0.001). Predictability of incisor proclination and intrusion was 69.8% and 53.3%, respectively. Multivariate linear regression revealed that DPA of proclination was significantly positively associated with predicted proclination (B = 0.174, P < 0.001), ipsilateral premolar extraction (B = 2.773, P < 0.001) and ipsilateral canine proclination (B = 1.811, P < 0.05), while negatively associated with molar distalization (B = - 2.085, P < 0.05). The DPA of intrusion was significantly positively correlated with predicted intrusion (B = 0.556, P < 0.001) while negatively associated with labial mini-implants (B = - 1.466, P < 0.001). The DPA of labial movement was significantly positively associated with predicted labial movement (B = 0.481, P < 0.001), while negatively correlated with molar distalization (B = - 1.004, P < 0.001), labial mini-implants (B = - 0.738, P < 0.001) and age (B = - 0.486, P < 0.05). CONCLUSIONS: For Class II division 2 patients, predicted incisor proclination (69.8%) and intrusion (53.3%) are partially achieved with clear aligner therapy. Excessive labial movement (0.7 mm) of incisors may be achieved. Incisor movement is influenced by predicted movement amount, premolar extraction, canine proclination, molar distalization, mini-implants and age.

Study on the Effect of α-Substituted Acrylate Monomers on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films.

Polymer-dispersed liquid crystals (PDLCs) show great application potential in the areas of displays and smart windows. However, their electro-optical (E-O) properties such as contrast ratio and threshold voltage still need further improvement. In this study, the effects of α-substituted acrylate monomers on the morphology and E-O properties of PDLC composite films were systematically studied. It was found that the large substituent tended to increase the void size of the polymer matrix, while the small fluorine substitution led to a microsphere-type polymer morphology, which deteriorated the E-O performance. Finally, a largely improved E-O performance of low threshold voltage (0.437 V/µm), low saturation voltage (1.012 V/µm), and high contrast ratio (27) was achieved in an 8 µm-thick film by the addition of a chlorine-substituted monomer. This study provides a new approach for optimizing PDLCs from a material perspective.

The predictability of orthodontic tooth movements through clear aligner among first-premolar extraction patients: a multivariate analysis.

BACKGROUND: The purpose was to determine the predictability of tooth movements through clear aligner among premolar extraction patients and to explore the effects of various factors on tooth movements. METHODS: A total of 31 extraction patients (10 males and 20 females; age 14-44) receiving clear aligner treatment (Invisalign) were enrolled in this study. The actual post-treatment models and pre-treatment models were superimposed using the palatal area as a reference and registered with virtual post-treatment models. A paired t test was used to compare the differences between actual and designed tooth movements of maxillary first molars, canines, and central incisors. A multivariate linear mixed model was performed to examine the influence of variables on actual tooth movements. RESULTS: Compared to the designed tooth movements, the following undesirable tooth movements occurred: mesial movement (2.2 mm), mesial tipping (5.4°), and intrusion (0.45 mm) of first molars; distal tipping (11.0°), lingual tipping (4.4°), and distal rotation of canines (4.9°); lingual tipping (10.6°) and extrusion (1.5 mm) of incisors. Age, crowding, mini-implant, overbite, and attachments have differential effects on actual tooth movements. Moreover, vertical rectangular attachments on canines are beneficial in achieving more predictable canine and incisor tooth movements over optimized attachments. Lingual tipping and extrusion of incisors were significantly influenced by the interaction effects between incisor power ridge and different canine attachments (p < 0.05). CONCLUSIONS: Incisors, canines, and first molars are subject to unwanted tooth movements with clear aligners among premolar extraction patients. Age, crowding, mini-implant, overbite, and attachments influence actual tooth movements. Moreover, vertical rectangular attachments on canines are beneficial in achieving more predictable incisor tooth movements over optimized canine attachments.

Development of an Artificial Intelligence System for the Automatic Evaluation of Cervical Vertebral Maturation Status.

BACKGROUND: Cervical vertebral maturation (CVM) is widely used to evaluate growth potential in the field of orthodontics. This study is aimed to develop an artificial intelligence (AI) system to automatically determine the CVM status and evaluate the AI performance. METHODS: A total of 1080 cephalometric radiographs, with the age of patients ranging from 6 to 22 years old, were included in the dataset (980 in training dataset and 100 in testing dataset). Two reference points and thirteen anatomical points were labelled and the cervical vertebral maturation staging (CS) was assessed by human examiners as gold standard. A convolutional neural network (CNN) model was built to train on 980 images and to test on 100 images. Statistical analysis was conducted to detect labelling differences between AI and human examiners, AI performance was also evaluated. RESULTS: The mean labelling error between human examiners was 0.48 ± 0.12 mm. The mean labelling error between AI and human examiners was 0.36 ± 0.09 mm. In general, the agreement between AI results and the gold standard was good, with the intraclass correlation coefficient (ICC) value being up to 98%. Moreover, the accuracy of CVM staging was 71%. In terms of F1 score, CS6 stage (85%) ranked the highest accuracy. CONCLUSIONS: In this study, AI showed a good agreement with human examiners, being a useful and reliable tool in assessing the cervical vertebral maturation.

Therapeutic potentials and modulatory mechanisms of fatty acids in bone.

Bone metabolism is a lifelong process that includes bone formation and resorption. Osteoblasts and osteoclasts are the predominant cell types associated with bone metabolism, which is facilitated by other cells such as bone marrow mesenchymal stem cells (BMMSCs), osteocytes and chondrocytes. As an important component in our daily diet, fatty acids are mainly categorized as long-chain fatty acids including polyunsaturated fatty acids (LCPUFAs), monounsaturated fatty acids (LCMUFAs), saturated fatty acids (LCSFAs), medium-/short-chain fatty acids (MCFAs/SCFAs) as well as their metabolites. Fatty acids are closely associated with bone metabolism and associated bone disorders. In this review, we summarized the important roles and potential therapeutic implications of fatty acids in multiple bone disorders, reviewed the diverse range of critical effects displayed by fatty acids on bone metabolism, and elucidated their modulatory roles and mechanisms on specific bone cell types. The evidence supporting close implications of fatty acids in bone metabolism and disorders suggests fatty acids as potential therapeutic and nutritional agents for the treatment and prevention of metabolic bone diseases.

A novel splice site variant in ANOS1 gene leads to Kallmann syndrome in three siblings.

Idiopathic hypogonadotropic hypogonadism (IHH) is a rare genetic disease caused by low doses of hypothalamic gonadotropin-releasing hormone (GnRH), leading to absence or delayed sexual development. Kallmann syndrome (KS) is characterized by IHH with anosmia or hyposmia. Here, we identified a novel splice site variant (c. 726+2T>G) of ANOS1 gene in three siblings with KS from a Chinese Han family by whole-exome sequencing (WES). In this family, KS is classified as an X-linked recessive inheritance pattern. This mutation was inherited from the mother by Sanger sequencing. An in vitro functional experiment has identified the deleterious effect of this mutation on the transcriptional level of ANOS1 gene. Importantly, the effectiveness of timely hormone replacement therapy was evaluated on the three siblings. Hence, finding genetic causes could be helpful in the early diagnosis and timely treatment of KS.

Polysiloxane-Based Side Chain Liquid Crystal Polymers: From Synthesis to Structure⁻Phase Transition Behavior Relationships.

Organosilicon polymer materials play an important role in certain applications due to characteristics of much lower glass transition temperatures (Tg), viscosities, surface energy, as well as good mechanical, thermal stabilities, and insulation performance stemming from the higher bond energy and the larger bond angles of the adjacent silicon-oxygen bond. This critical review highlights developments in the synthesis, structure, and phase transition behaviors of polysiloxane-based side chain liquid crystal polymers (PSCLCPs) of linear and cyclic polysiloxanes containing homopolymers and copolymers. Detailed synthetic strategies are elaborated, and the relationship between molecular structures and liquid crystalline phase transition behaviors is systematically discussed, providing theoretical guidance on the molecular design of the materials.

Angular Photochromic LC Composite Film for an Anti-Counterfeiting Label.

In the harsh application environment, improving the mechanical properties of liquid crystal materials is a fundamental and important problem in the design of anti-counterfeit materials. In this paper, by a stepwise polymerization of first, photo-polymerization and subsequently thermal-polymerization, a coexistent polymer dispersed network was first constructed in cholesteric liquid crystal materials containing a photo-polymerizable system of urethane acrylate and a thermo-polymerizable system of isocyanate. Results revealed that the coexistent polymer dispersed network exhibited largely enhanced mechanical performance, and the networks obtained by different methods had different contributions to the enhancement of the peel strength and toughness of the composite films. Then an angular photochromic anti-fake label based on a coexistent polymer dispersed network with enhanced mechanical and apparent angular discoloration characteristics, suitable for practical applications, was successfully achieved.