A case of recurrent proximal femoral fracture after open reduction and internal fixation with bilateral locking plates for a Rorabeck type II periprosthetic fracture.

INTRODUCTION AND IMPORTANCE: Periprosthetic distal femur fractures (PDFFs) are rare complications that may occur during or after total knee arthroplasty (TKA). The incidence of PDFFs is increasing. Plate internal fixation has demonstrated positive results. However, there is limited research available on the recurrence of periimplant fractures following open reduction and internal fixation with bilateral locking plates. CASE PRESENTATION: A 70-year-old female patient was diagnosed with a Rorabeck type II fracture. Based on the patient's physical condition and available surgical options, minimally invasive open reduction, bilateral plate fixation, and allograft artificial bone grafting were chosen. The postoperative recovery was successful. However, the patient experienced a fall 2 months after the surgery, resulting in a proximal femoral fracture. After considering the patient's condition and family preferences, conservative treatment was ultimately decided upon. CLINICAL DISCUSSION: Minimally invasive bilateral Locking Compression Plate (LCP) as a surgical approach can effectively reduce surgical risks prior to the procedure. Careful selection of screws and the use of C-arm fluoroscopy during plate contouring and fixation are essential to prevent screw penetration through the contralateral cortex. Treatment outcomes were not impacted in patients with normal bone mass; however, in this particular case, the patient had severe osteoporosis, significantly increasing the risk of refracture. It is crucial to improve postoperative monitoring and raise awareness about safety among patients and their families. CONCLUSION: The management of periprosthetic distal femur fractures (PDFFs) is influenced by the type of fracture and bone quality. Mechanical stability and stress dispersion of internal fixation are key factors to consider. In the perioperative setting, involving experienced clinicians is essential to reduce the risk of secondary injuries that may impact treatment outcomes, especially when choosing screws for fixation in patients with low bone density.

Plasma Ionomic Profile and Interaction Patterns in Coronary Artery Disease Patients.

Humans are exposed to various chemical elements that have been associated with the development and progression of diseases such as coronary artery disease (CAD). Unlike previous research, we employed a multi-element approach to investigate CAD patients and those with comorbid conditions such as diabetes (CAD-DM2), high blood pressure (CAD-HBP), or high blood lipids (CAD-HBL). Plasma concentrations of 21 elements, including lithium (Li), boron (B), aluminum (Al), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), strontium (Sr), cadmium (Cd), tin (Sn), stibium (Sb), barium (Ba), and lead (Pb), were measured in CAD patients (n = 201) and healthy subjects (n = 110) using inductively coupled plasma-mass spectrometry (ICP-MS). Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) models were utilized to analyze the ionomic profiles. Spearman correlation analysis was employed to identify the interaction patterns among individual elements. We found that levels of Ba, Li, Ni, Zn and Pb were elevated in the CAD group compared to the healthy group, while Sb, Ca, Cu, Ti, Fe, and Se were lower. Furthermore, the CAD-DM2 group exhibited higher levels of Ni and Cd, while the CAD-HBP group showed lower levels of Co and Mn. In the CAD-HBL group, Ti was increased, whereas Ba, Cr, Cu, Co, Mn, and Ni were reduced. In conclusion, ionomic profiles can be utilized to differentiate CAD patients from healthy individuals, potentially providing insights for future treatment or dietary interventions.

Exerkine ß-aminoisobutyric acid protects against atrial structural remodeling and atrial fibrillation in obesity via activating AMPK signaling and improving insulin sensitivity.

Moderate exercise decreases the risk for atrial fibrillation (AF), an effect which is probably mediated via exercise-stimulated release of exerkines. ß-Aminoisobutyric acid (BAIBA), a novel exerkine, has been reported to provide protective benefits against many cardiovascular diseases, yet its role in AF remains elusive. Herein, using a mouse model of obesity-related AF through high-fat diet (HFD) feeding, we found that 12-week drinking administration of BAIBA (170 mg/kg/day) decreased AF susceptibility in obese mice. Atrial remodeling assessment showed that BAIBA attenuated obesity-induced atrial hypertrophy and interstitial fibrosis, thereby ablating the substrate for AF. Of note, to our knowledge, this is the first report of the direct association of BAIBA and hypertrophy. BAIBA has been reported to be a key regulator of glucose and lipid metabolism, and we found that BAIBA alleviated insulin resistance in obese mice. Transcriptional analysis of metabolism-related genes showed that BAIBA increased the transcription of fatty acids metabolism-related genes in the atria of lean mice but not in that of obese mice. Mechanistic investigation showed that BAIBA stimulated AMP-activated protein kinase (AMPK) signaling in the atria of obese mice and palmitic acid (PA)-treated neonatal rat cardiomyocytes (NRCM), whereas inhibition of AMPK via Compound C attenuated BAIBA-conferred cardioprotection against hypertrophy and insulin resistance in PA-treated NRCM. Collectively, BAIBA attenuates AF susceptibility in obese mice via activated AMPK signaling and resultant improvement of insulin sensitivity, thereby providing perspectives on the potential therapeutic role of BAIBA in AF treatment.

[Metabolic mechanism and intervention strategy of atrial fibrillation in the elderly].

Atrial fibrillation (AF) is a cardiovascular epidemic that occurs primarily in the elderly with primary cardiovascular diseases, leading to severe consequences such as stroke and heart failure. The heart is an energy-consuming organ, which requires a high degree of metabolic flexibility to ensure a quick switch of metabolic substrates to meet its energy needs in response to physiological and pathological stimulation. Metabolism is closely related to the occurrence of AF, and AF patients manifest metabolic inflexibility, such as insulin resistance and the metabolic shift from aerobic metabolism to anaerobic glycolysis. Moreover, our research group and the others have shown that metabolic inflexibility is a crucial pathologic mechanism for AF. Energy metabolism is closely linked to the aging process and aging-related diseases, and impaired metabolic flexibility is considered as an essential driver of aging. Therefore, this review focuses on the alteration of metabolic flexibility in the elderly and reveals that impaired metabolic flexibility may be an important driver for the high prevalence of AF in the elderly, hoping to provide intervention strategies for the prevention and treatment of AF in the elderly.

Preparing Data for Artificial Intelligence in Pathology with Clinical-Grade Performance.

The pathology is decisive for disease diagnosis but relies heavily on experienced pathologists. In recent years, there has been growing interest in the use of artificial intelligence in pathology (AIP) to enhance diagnostic accuracy and efficiency. However, the impressive performance of deep learning-based AIP in laboratory settings often proves challenging to replicate in clinical practice. As the data preparation is important for AIP, the paper has reviewed AIP-related studies in the PubMed database published from January 2017 to February 2022, and 118 studies were included. An in-depth analysis of data preparation methods is conducted, encompassing the acquisition of pathological tissue slides, data cleaning, screening, and subsequent digitization. Expert review, image annotation, dataset division for model training and validation are also discussed. Furthermore, we delve into the reasons behind the challenges in reproducing the high performance of AIP in clinical settings and present effective strategies to enhance AIP's clinical performance. The robustness of AIP depends on a randomized collection of representative disease slides, incorporating rigorous quality control and screening, correction of digital discrepancies, reasonable annotation, and sufficient data volume. Digital pathology is fundamental in clinical-grade AIP, and the techniques of data standardization and weakly supervised learning methods based on whole slide image (WSI) are effective ways to overcome obstacles of performance reproduction. The key to performance reproducibility lies in having representative data, an adequate amount of labeling, and ensuring consistency across multiple centers. Digital pathology for clinical diagnosis, data standardization and the technique of WSI-based weakly supervised learning will hopefully build clinical-grade AIP.

The role of the miR-4306/PAK6 axis in degenerative nucleus pulposus cells in human intervertebral disc degeneration.

Intervertebral disc degeneration (IDD), characterized by degenerative changes that occur in intervertebral discs due to aging or structural injury, is thought to be the most common cause of lower back pain. Recent studies have shown that microRNAs (miRNAs) have a critical role in the etiopathogenesis of IDD. In the current study, we aimed to determine the role of miRNAs in mediating the underlying mechanisms associated with IDD. First, differentially expressed miRNAs (DEmiRNAs) were identified using the GEO database, and subsequently confirmed by RT-qPCR and in situ hybridization. We found that miR-4306 expression was significantly decreased in human nucleus pulposus (NP) tissues compared with healthy controls, and was negatively correlated with the patients' Pfirrmann grade. To determine the mechanism by which miR-4306 was involved in IDD pathogenesis, we examined the effects of overexpressing or silencing miR-4306 on extracellular matrix (ECM) synthesis/degradation, proliferation, autophagy and apoptosis of human degenerated NP cells isolated from IDD patients. Next, we used dual-luciferase reporter assays to demonstrate that miR-4306 interacted with the 3'-untranslated regions of p21-activated kinase 6 (PAK6) mRNA, resulting in significant suppression of PAK6 expression. This effect was abolished by miR-4306 binding site mutations. Using miR-4306/PAK6 gain-of-function and loss-of-function studies in human degenerated NP cells, we demonstrated that miR-4306 promoted NP cell proliferation, ECM synthesis and autophagy, while inhibiting apoptosis and ECM degradation via PAK6. Thus, our findings indicate that miR-4306, acting via PAK6, has an important role in IDD and can be used as a promising therapeutic target for the treatment of patients with IDD.

Synthesis of rare-earth metal complexes with a morpholine-functionalized ß-diketiminato ligand and their catalytic activities towards C-O and C-N bond formation.

Unusual tridentate ß-diketiminato rare-earth metal chlorides LRECl(µ-Cl)2Li(THF)2 (RE = Y (1a), Yb (1b), and Lu (1c); L = MeC(NDipp)CHC(Me)N(CH2)2NC4H8O; Dipp = 2,6-iPr2C6H3) and the corresponding dialkyl complexes LRE(CH2SiMe3)2 (RE = Y (2a), Yb (2b), and Lu (2c)) were prepared by reaction of a morpholine-functionalized ß-diketiminato proligand HL with anhydrous RECl3 and rare-earth metal trialkyl complexes RE(CH2SiMe3)3(THF)2, respectively. In 1 and 2, the morpholine moiety displayed a stable chair conformation and the resulting ligand coordinated to the rare-earth metal ion in a [NNN]-tridentate chelating fashion. Further studies demonstrated that these dialkyl complexes showed high activity towards the catalytic formation of C-O and C-N bonds in the alcoholysis of isothiocyanates and aminolysis of epoxides. A series of O-thiocarbamate derivatives were achieved in good to excellent yields by reaction of various alcohols with aromatic and aliphatic-substituted isothiocyanates at room temperature. In addition, under solvent-free conditions, the ring-opening reaction of terminal and internal epoxides with arylamines yielded the corresponding ß-amino alcohols with excellent regioselectivity. More importantly, a novel ß-diketiminato/anilido yttrium alkyl complex LY(NHDipp)(CH2SiMe3) (5a) was isolated and characterized by the stoichiometric reaction of 2a with diisopropylaniline.

Rare-Earth-Metal-Complex-Catalyzed Hydroalkoxylation and Tandem Hydroalkoxylation/Cyclohydroamination of Isocyanates: Synthesis of Carbamates and Oxazolidinones.

Novel N,N,N-tridentate ß-diketiminato rare-earth-metal dialkyl complexes LRE(CH2SiMe3)2 [RE = Y (1a), Gd (1b), Yb (1c), Lu (1d); L = MeC(NDipp)CHC(Me)N(CH2)2NC4H8, where Dipp = 2,6-iPr2C6H3] have been conveniently synthesized by one step from reactions of the rare-earth-metal trialkyl complexes RE(CH2SiMe3)3(THF)2 (THF = tetrahydrofuran) with a pyrrolidine-functionalized ß-diketiminate HL, and their catalytic behaviors toward hydroalkoxylation and tandem hydroalkoxylation/cyclohydroamination of isocyanates have been described. These rare-earth-metal catalysts exhibited high efficiency in the hydroalkoxylation of isocyanates, providing a variety of N-alkyl and N-aryl carbamate derivatives under mild reaction conditions with a rather low catalyst loading (0.04 mol %). More significantly, they can promote a tandem hydroalkoxylation/cyclohydroamination reaction between terminal and internal propargylic alcohols with substituted arylisocyanates, leading to the efficient synthesis of methylene and (Z)-selective arylidene oxazolidinones in good-to-high yields via consecutive C-O and C-N bond formation. The stoichiometric reaction of 1a with p-tolylisocyanate generated an unusual dinuclear yttrium complex, {[η2-(4-MePhNCO)(CH2SiMe3)]Y[µ-η2:η1:η1-(4-MePhNCO)CC(Me)(NDipp)C(Me)N(CH2)2NC4H8]}2 (7a), with two different amidate units, which underwent an sp2 C-H bond activation of the ß-diketiminato backbone, followed by the insertion of isocyanate.

[Effect of acupuncture for regulating spleen and stomach on aspirin resistance in patients with type 2 diabetes mellitus: a randomized controlled trial].

OBJECTIVE: To observe the effect of acupuncture for regulating spleen and stomach on aspirin resistance in patients with type 2 diabetes mellitus (T2DM) and explore the effect mechanism. METHODS: A total of 68 T2DM patients complicated with aspirin resistance were randomized into an observation group and a control group, 34 cases in each one. On the base of the conventional treatment for diabetes, aspirin enteric-coated tablets were prescribed for oral administration, 100 mg each time, once daily in the control group. In the observation group, on the basis of the treatment as the control group, acupuncture was used for regulating spleen and stomach at Zhongwan (CV 12), Zusanli (ST 36), Yinlingquan (SP 9), Hegu (LI 4), etc., once daily. The treatment for 1 week was as one course and 4 courses of treatment were required totally in two groups. Before and After treatment, the indexes of platelet function (platelet aggregation rate [PAG] and salicylic acid concentration), the indexes of vascular endothelial function (6-keone prostaglandin F1α[6-keto-PGF1α], thromin B2 [TXB2] and cyclooxysynthase-2 [COX-2]), blood glucose (fasting plasma glucose [FPG], 2 h plasma glucose [2h PG] and glycosylated hemoglobin [HbA1c]), insulin resistance index (HOMA-IR), blood lipid indexes (total cholesterol [TC], triacylglycerol [TG], high-density lipoprotein cholesterol [HDL-C] and low-density lipoprotein cholesterol [LDL-C]) and the total score of TCM symptoms were observed in the patients of two groups. Clinical therapeutic effect and safety was compared in the patients between the two groups after treatment and the recurrence rate of cardiocerebrovascular events was followed up 6 months after treatment. RESULTS: After treatment, PAG, salicylic acid concentration, TXB2, COX-2, FPG, 2h PG, HbA1c, HOMA-IR, LDL-C, TC, TG and the total scores of TCM symptoms were all reduced as compared with those before treatment in the two groups (P<0.01, P<0.05), and 6-keto-PGF1αand HDL-C were increased as compared with those before treatment in the two groups (P<0.01, P<0.05). In comparison with the control group, the aforementioned indexes in the observation group were all improved significantly (P<0.01). The total effective rate was 91.2% (31/34) in the observation group, higher than 70.6% (24/34) in the control group (P<0.05). In follow up visit, the recurrence rate of cardiocerebrovascular events was 14.7% (5/34) in the observation group, lower than 29.4% (10/34) in the control group (P<0.05). The therapies were safe and had no obvious adverse reactions in both two groups. CONCLUSION: Acupuncture for regulating spleen and stomach combined with aspirin enteric-coated tablets relieve insulin resistance and reduces blood glucose and lipid as well as the recurrence rate of cardiocerebrovascular events in the patients with T2DM, which is probably related to the regulation of insulin resistance and the improvement of vascular endothelial function. This combined therapy achieves the better effect on aspirin resistance as compared with simple aspirin enteric-coated tablets.

Serum TBA and GCA Levels Across Pregnancy and the Gestational Age-Specific Reference Intervals for Pregnant Chinese.

BACKGROUND: Reference intervals of clinical laboratory indexes are the basis of interpretation of test results. While intrahepatic cholestasis of pregnancy (ICP) could severely threaten maternal and fetal health, reference intervals of the biomarkers serum total bile acids (TBA) and glycocholic acid (GCA) are unsatisfactory. The purpose of this study was to derive gestational age-specific reference intervals for serum TBA and GCA in a Chinese population to promote early diagnosis of ICP. METHODS: A total of 416 healthy pregnant Chinese were recruited and divided into three groups by gestational age: 140 in the first trimester (1 - 13 weeks) group, 136 in the second trimester (14 - 27 weeks) group, and 140 in the third trimester (≥ 28 weeks) group. Serum TBA and GCA levels were measured respectively by cyclic enzymatic method and latex enhanced immune turbidimetry. Reference intervals were calculated with non-parametric method. RESULTS: The reference intervals of serum TBA are 0.90 - 6.60 µmol/L, 1.20 - 9.10 µmol/L, and 1.50 - 8.90 µmol/L respectively in the first, second, and third trimester. The reference intervals of serum GCA are 0.24 - 1.14 µg/mL in the first and second trimesters (combined) and 0.00 - 2.04 µg/mL in the third trimester. CONCLUSIONS: Gestational age-specific reference intervals of serum TBA and GCA for pregnant Chinese were derived in strict accordance with CLSI C28-A3 guidelines, which will be valuable for early diagnosis of ICP.

Sub-wavelength grating assisted mode order converter on the SOI substrate.

We have designed three mode order converters using the sub-wavelength grating on the silicon-on-insulator substrate. The proposed mode order converters can separately realize the mode order conversion from the fundamental transverse electric mode to the first-order transverse electric mode (TE0-to-TE1), the second-order transverse electric mode (TE0-to-TE2) and the third-order transverse electric mode (TE0-to-TE3) with compact device sizes and good performances. The simulation results show that the mode order conversion efficiencies of TE0-to-TE1, TE0-to-TE2 and TE0-to-TE3 are larger than 94.4%, 95.7% and 83.7% in the wavelength ranging from 1.5 µm to 1.6 µm, the corresponding device length are 8.72 µm, 4.98 µm and 14.54 µm. In addition, the mode order converter can be fabricated with only once etching which will be advantage to the device fabrication.

Reference Intervals for Serum Creatinine with Jaffe's Method in Healthy Chinese Geriatric Population.

BACKGROUND: Reliable reference intervals (RIs) for the serum creatinine (SCr), assayed by Jaffe's method and categorized in small intervals, are still lacking in elderly population. The study aims to establish RIs for SCr with Jaffe's method in healthy geriatric population of China. METHODS: Eight hundred twenty cases from six representative geographical regions in China (including 369 male cases and 374 female cases) of apparently healthy Chinese elderly aged 60 - 90 years were recruited. SCr were analyzed by an ARCHITECT c8000 biochemical analyzer with Jaffe's method, and RIs for Scr with Jaffe's method were determined following CLSI C28-A3 guidelines using a nonparametric method. RESULTS: In apparently healthy Chinese geriatric population of China, the RIs for Scr with Jaffe's method were 69.4 ~ 113.1, 74.1 ~ 122.1, 75.2 ~ 126.9 µmol/L, respectively, for males aged 61 - 70, 71 - 80, 81 - 90 years and 60.7 ~ 91.6, 62.2 ~ 102.5, 86.5 ~ 107.2 µmol/L, respectively, for females aged 61 - 70, 71 - 80, 81 - 90 years. CONCLUSIONS: The RIs for Scr using Jaffe's method were established within apparently healthy geriatric Chinese population according to CLSI C28-A3 document, providing a reference for clinical practice.

[Clinical trials of acupuncture treatment of post-stroke shoulder pain].

OBJECTIVE: To observe the clinical therapeutic effect of "Tiaoshen Zhitong" (mental regulating and pain relieving) needling and its influence on serological indicators in the treatment of post-stroke shoulder pain, so as to provide new therapeutic thoughts and approach for post-stroke shoulder pain. METHODS: A total of 80 inpatients with post-stroke shoulder pain were randomly divided into a control group (routine needling, 39 cases) and an observation group ("Tiaoshen Zhitong" needling, 41 cases) according to the random number table. Patients of the two groups accepted basic medication treatment including anticoagulants, hypotensive drugs, hypoglycermic drugs, lipid-lowering drugs, etc. In addition, patients of the control group were also treated by routine acupuncture stimulation (uniform reinforcing-reducing stimulation) of Jianyu (LI15), Jianqian (EX-UE12), Jianhou (Extra), Jianliao (TE14), Waiguan (TE5) and Hegu (LI4) on the affected side, and those of the observation group also treated by "Tiaoshen Zhitong" needling of Ear-Shenmen (MA-TF1), bilateral Neiguan (PC6, lifting-thrusting-reducing method), Shuigou (GV26, lifting-thrusting-reducing method), and Jianyu (LI15), Jianliao(TE14), Jianzhen (SI9) and Yanglingquan (GB34, the latter 4 points were stimulated with uniform reinforcing-reducing method) on the affected side. The treatment was given once every day, 6 days a week for 4 weeks. The pain severity was assessed by using visual analogue scale (VAS), the upper limb function evaluated by using Fugl-Meyer assessment (FMA) scale, the shoulder-joint function evaluated by using Constant-Murley score (CMS) questionnaire, and the daily living ability assessed by using Barthel index (BI) scale. The enzyme linked immunosorbent assay (ELISA) was used to determine the contents of serum beta-endorphin (ß-EP), enkephalin (ENK) and dynorphin (Dyn). The clinical therapeutic effect was evaluated by using Nimodipine scale method. RESULTS: Of the 39 and 41 cases in the control and observation groups, 7(17.95%) and 12(29.27%) were basically cured, 12(30.77%) and 13(31.71%) experienced marked improvement, 8(20.51%) and 11(26.83%) were effective, 12(30.77%) and 5 (12.19%) failed, with the total effective rate being 69.23% and 87.80%, respectively. The effective rate of the observation group was significantly higher than that of the control group (P<0.05). After the treatment, the VAS score was obviously reduced (P<0.01), and the scores of FMA scale, CMS questionnaire and BI scale, and contents of serum ß-EP, ENK and Dyn were all increased obviously in the two groups compared with their own pre-treatment (P<0.01). The therapeutic effect of "Tiaoshen Zhitong" needling was significantly superior to that of the routine needling in lowering VAS, and in raising scores of FMA scale, CMS questionnaire and BI scale and in up-regulating serum ß-EP, ENK and Dyn levels (P<0.01). CONCLUSION: "Tiaoshen Zhitong" needling is effective in reducing post-stroke shoulder pain and improving the motor function of the upper limb and shoulder-joint as well as the quality of daily life in stroke patients with shoulder pain. Its analgesic effect is probably related to the increase of the levels of serum ß-EP, ENK and Dyn.

Association of hepatitis B infection with high-risk complications in total joint arthroplasty.

BACKGROUND: An increasing number of patients with hepatitis B virus (HBV) infection are undergoing total joint arthroplasty (TJA) surgery in China. Less attention is provided to the special populations and the purpose of this study is to assess the effect of HBV infection on the prognosis TJAs. METHODS: We retrospectively reviewed patients who underwent elective primary hip and knee arthroplasties in Shanghai Huashan Hospital from 2013 to 2016. Non-hepatitis B cohort was built to match the case cohort to identify whether HBV infection was a risk factor associated with postoperative complications. A total number of 196 patients who underwent primary TJAs were involved in the study, including 49 patients with hepatitis B and 147 non-hepatitis B subjects. RESULTS: Among all the patients with TJAs, 5.5% of patients were infected with HBV for the first time. The incidence rate of complications in patients after arthroplasty with hepatitis B infection was significantly higher than that in patients without hepatitis B (10.2% compared to 4.7%, P < 0.01). Surgical related complications (6.1% compared to 3.4%) and general medical complications (4.1% compared to 1.3%) were higher than those in non-B hepatitis group. Compared with non-B hepatitis group, the overall risk of hepatitis B infection increased by 25% (95% CI, 1.04-1.46; p < 0.01). Similar results were obtained for medical and surgical complications. HBV infection presented a 31% increased risk (95% CI, 1.02-1.62; p < 0.01) for medical complication and an 18% increased risk (95% CI, 1.10-1.26; p < 0.01) for surgical complication. No statistical difference was found between the surgical methods and sex. However, a significant difference of C-reactive protein (CRP) level was found between HBV infection group and the matched non-infected group (P < 0.01). CONCLUSION: This is the first study to investigate the risk of perioperative complications of hepatitis B in Chinese TJAs patients. In consideration of the large population of HBV infection in China, more attention and medical care should be provided to patients with HBV infection who need to undergo TJA operation.

Switchable multifunctional terahertz metasurfaces employing vanadium dioxide.

In this paper, we design a type of switchable metasurfaces by employing vanadium dioxide (VO2), which possess tunable and diversified functionalities in the terahertz (THz) frequencies. The properly designed homogeneous metasurface can be dynamically tuned from a broadband absorber to a reflecting surface due to the insulator-to-metal transition of VO2. When VO2 is in its insulating state, the metasurface can efficiently absorb the normally incident THz wave in the frequency range of 0.535-1.3 THz with the average absorption of ~97.2%. Once the VO2 is heated up and switched to its fully metallic state, the designed metasurface exhibits broadband and efficient reflection (>80%) in the frequency range from 0.5 to 1.3 THz. Capitalizing on such meta-atom design, we further extend the functionalities by introducing phase-gradients when VO2 is in its fully metallic state and consequently achieve polarization-insensitive beam-steering and polarization-splitting, while maintaining broadband absorption when VO2 is in insulating state.

Nonradiating anapole states in nanophotonics: from fundamentals to applications.

Nonradiating sources are nontrivial charge-current distributions that do not generate fields outside the source domain. The pursuit of their possible existence has fascinated several generations of physicists and triggered developments in various branches of science ranging from medical imaging to dark matter. Recently, one of the most fundamental types of nonradiating sources, named anapole states, has been realized in nanophotonics regime and soon spurred considerable research efforts and widespread interest. A series of astounding advances have been achieved within a very short period of time, uncovering the great potential of anapole states in many aspects such as lasing, sensing, metamaterials, and nonlinear optics. In this review, we provide a detailed account of anapole states in nanophotonics research, encompassing their basic concepts, historical origins, and new physical effects. We discuss the recent research frontiers in understanding and employing optical anapoles and provide an outlook for this vibrant field of research.

Active control of anapole states by structuring the phase-change alloy Ge2Sb2Te5.

High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities. The great wealth of multipolar responses has not only brought in new physical insight but also spurred practical applications. However, how to make such a colorful resonance palette actively tunable is still elusive. Here, we demonstrate that the structured phase-change alloy Ge2Sb2Te5 (GST) can support a diverse set of multipolar Mie resonances with active tunability. By harnessing the dramatic optical contrast of GST, we realize broadband (Δλ/λ ~ 15%) mode shifting between an electric dipole resonance and an anapole state. Active control of higher-order anapoles and multimodal tuning are also investigated, which make the structured GST serve as a multispectral optical switch with high extinction contrasts (>6 dB). With all these findings, our study provides a new direction for realizing active nanophotonic devices.

On-Chip Detection of Optical Spin-Orbit Interactions in Plasmonic Nanocircuits.

On-chip manipulating and controlling the temporal and spatial evolution of light are of crucial importance for information processing in future planar integrated nanophotonics. The spin and orbital angular momentum of light, which can be treated independently in classical macroscopic geometrical optics, appear to be coupled on subwavelength scales. We use spin-orbit interactions in a plasmonic achiral nanocoupler to unidirectionally excite surface plasmon polariton modes propagating in seamlessly integrated plasmonic slot waveguides. The spin-dependent flow of light in the proposed nanophotonic circuit allows on-chip electrical detection of the spin state of incident photons by integrating two germanium-based plasmonic-waveguide photodetectors. Consequently, our device serves as a compact (∼6 × 18 µm2) electrical sensor for photonic spin Hall dynamics. The demonstrated configuration opens new avenues for developing highly integrated polarization-controlled optical devices that would exploit the spin-degree of freedom for manipulating and controlling subwavelength optical modes in nanophotonic systems.

Laser Writing of Bright Colors on Near-Percolation Plasmonic Reflector Arrays.

Coloration by surface nanostructuring has attracted a great deal of attention by the virtue of making use of environment-friendly recyclable materials and generating nonbleaching colors. Recently, it was found possible to delegate the task of color printing to laser postprocessing that modifies carefully designed and fabricated nanostructures. Here we take the next crucial step in the development of structural color printing by dispensing with preformed nanostructures and using instead near-percolation metal films atop dielectric-metal sandwiches, that is, near-percolation plasmonic reflector arrays. Scanning rapidly (∼20 µm/s) across 4 nm-thin island-like gold films supported by 30 nm-thin silica layers atop 100 nm-thick gold layers with a strongly focused Ti-sapphire laser beam, while adjusting the average laser power from 1 to 10 mW, we produce bright colors varying from green to red by laser-heating-induced merging and reshaping of gold islands. Selection of strongly heated islands and their reshaping, both originating from excitation of plasmonic resonances, are strongly influenced by the polarization direction of laser illumination, so that the colors produced are well pronounced only when viewed with the same polarization. Conversely, the laser color writing with circular polarizations results in bright polarization-independent color images. The fabrication procedure for near-percolation reflector arrays is exceedingly simple and scalable to mass production, while the laser-induced modification occurs inherently with the subwavelength resolution. This combination of features makes the approach developed for laser color writing readily amenable for practical implementation and use in diverse applications ranging from nanoscale patterning for security marking to large-scale color printing for decoration.