Application of Carbon Nanoparticles in Transoral Endoscopic Thyroidectomy Vestibular Approach for Unilateral Papillary Thyroid Cancer.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach (TOETVA) is newly applied technology. Carbon nanoparticles (CNs) are novel lymph node tracers that have been widely used in China to help remove central lymph nodes (CLNs) and protect the parathyroid glands (PGs) in open thyroid cancer surgery. This study is to evaluate the effectiveness and safety of CNs in TOETVA. MATERIALS AND METHODS: A total of 158 patients who underwent TOETVA with unilateral papillary thyroid carcinoma were enrolled in this study from March 2019 to February 2022. The participants were divided into a CNs group (n=88) and a control group (n=70), based on whether they received a intraoperative injection of CNs or not. Meanwhile, the CNs group were additionally divided into 2 subgroups, leakage subgroup (n=26) and standard subgroup (n=62). The 2 groups and subgroups were compared in terms of patient characteristics, perioperative clinical results, and postoperative outcomes. RESULTS: All common metrics had no significant differences were found between the CNs group and the control group (P>0.05). The standard subgroup of CNs group had advantage over the control group on PGs identification (59/62 vs. 59/70 for superior PG, 56/62 vs. 52/70 for inferior PG, P<0.05). Moreover, the standard subgroup harvested more CLNs than the control group (8.97±2.96 vs. 7.47±2.93, P<0.05). More operation time was spent on the leakage subgroup of CNs group than the control group (160.00±17.61 vs. 140.00±13.32, P<0.05). Meanwhile, the leakage subgroup had disadvantage on intraoperative hemorrhage (26.15±10.80 vs. 21.21±7.09, P<0.05) and hospital durations (4.96±0.72 vs. 4.57±0.69, P<0.05). Furthermore, the leakage group identified fewer inferior PG than the control group (7/26 vs. 52/70, P<0.05). Contrary to the standard subgroup, the CLNs of the leakage subgroup was also unsatisfactory compared with the control group (4.96±1.84 vs. 7.47±2.93, P<0.05). CONCLUSIONS: The application of CNs suspension tracing technology has a definite effect in TOETVA. It can improve the thoroughness of lymph node dissection in the central region and enhance recognition of the PG. However, refined extracapsular anatomy is indispensable to prevent CN leakage. Leaked CNs will also be counterproductive to the operation.

Observation of Ferroelectric Lithography on Biodegradable PLA Films.

Ferroelectric lithography, which can purposefully control and pattern ferroelectric domains in the micro-/nanometer scale, has extensive applications in data memories, field-effect transistors, race-track memory, tunneling barriers, and integrated biochemical sensors. In pursuit of mechanical flexibility and light weight, organic ferroelectric polymers such as poly(vinylidene fluoride) are developed; however, they still suffer from complicated stretching processes of film fabrication and poor degradability. These poor features severely hinder their applications. Here, the ferroelectric lithography on the biocompatible and biodegradable poly(lactic acid) (PLA) thin films at room temperature is demonstrated. The semicrystalline PLA thin film can be easily fabricated through the melt-casting method, and the desired domain structures can be precisely written according to the predefined patterns. Most importantly, the coercive voltage (Vc ) of PLA thin film is relatively low (lower than 30 V) and can be further reduced with the decrease of the film thickness. These intriguing behaviors combined with satisfying biodegradability make PLA thin film a desirable candidate for ferroelectric lithography and enable its future application in the field of bioelectronics and biomedicine. This work sheds light on further exploration of ferroelectric lithography on other polymer ferroelectrics as well as their application as nanostructured devices.

A Homochiral Fulgide Organic Ferroelectric Crystal with Photoinduced Molecular Orbital Breaking.

Thermally triggered spatial symmetry breaking in traditional ferroelectrics has been extensively studied for manipulation of the ferroelectricity. However, photoinduced molecular orbital breaking, which is promising for optical control of ferroelectric polarization, has been rarely explored. Herein, for the first time, we synthesized a homochiral fulgide organic ferroelectric crystal (E)-(R)-3-methyl-3-cyclohexylidene-4-(diphenylmethylene)dihydro-2,5-furandione (1), which exhibits both ferroelectricity and photoisomerization. Significantly, 1 shows a photoinduced reversible change in its molecular orbitals from the 3 π molecular orbitals in the open-ring isomer to 2 π and 1 σ molecular orbitals in the closed-ring isomer, which enables reversible ferroelectric domain switching by optical manipulation. To our knowledge, this is the first report revealing the manipulation of ferroelectric polarization in homochiral ferroelectric crystal by photoinduced breaking of molecular orbitals. This finding sheds light on the exploration of molecular orbital breaking in ferroelectrics for optical manipulation of ferroelectricity.

Discovery of Ferroelectricity in the Fullerene Adduct C60S8.

Fullerenes offer versatile functionalities and are promising materials for a widespread range of applications from biomedicine and energy to electronics. Great efforts have been made to manipulate the symmetries of fullerene and its derivatives for studying material properties and novel effects, such as ferroelectricity with polar symmetry; however, no documentary report has been obtained to realize their ferroelectricity. Here, for the first time, we demonstrated clear ferroelectricity in a fullerene adduct formed by C60 and S8. More is different: the combination of the most symmetric molecule C60 with the highest Ih symmetry and molecule S8 with high D4d symmetry resulted in the polar C60S8 adduct with a low crystallographic symmetry of the C2v (mm2) point group at room temperature. The presented C60S8 undergoes polar-to-polar ferroelectric phase transition with the mm2Fm notation, whose ferroelectricity was confirmed by a ferroelectric hysteresis loop and ferroelectric domain switching. This finding opens up a new functionality for fullerenes and sheds light on the exploration of more ferroelectric fullerenes.

Transoral Endoscopic Thyroidectomy Vestibular Approach Versus Gasless Transaxillary Endoscopic Thyroidectomy for Patients With Unilateral Papillary Thyroid Carcinoma: A Retrospective Study.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach (TOETVA) and gasless transaxillary endoscopic thyroidectomy (GTET) are 2 newly applied technologies. This study is to compare the 2 approaches from the aspects of effectiveness and safety. MATERIALS AND METHODS: A total of 339 patients who underwent TOETVA or GTET with unilateral papillary thyroid carcinoma were enrolled in this study from March 2019 to February 2022. The 2 groups were compared in terms of patient characteristics, perioperative clinical results, and postoperative outcomes. RESULTS: The operative time of the TOETVA group was significantly longer than the GTET group (141.39±16.11 vs. 98.45±12.24, P <0.05). The TOETVA group had advantages over GTET group when the reduction of parathyroid hormone was compared (19.18±17.43 vs. 23.07±15.72, P <0.05). Meanwhile, more parathyroids were detected in central neck specimens in GTET group (40/181 vs. 21/158, P <0.05). TOETVA had an advantage on total number of central lymph nodes over GTET (7.65±3.11 vs. 4.99±2.45, P <0.05), whereas the number of positive central lymph nodes was similar ( P >0.05). No differences were found between the 2 groups on other data. CONCLUSIONS: TOETVA and GTET are both safe and effective for unilateral papillary thyroid carcinomas. TOETVA has advantage on protection of inferior parathyroid glands and harvest of central lymph node dissection. Meanwhile, GTET can save more time compared with TOETVA. Surgeons and patients should freely choose the approaches based on their demands.

Fluorination Enables Dual Ferroelectricity in Both Solid- and Liquid-Crystal Phases.

Ferroelectric materials are a special type of polar substances, including solids or liquid crystals. However, obtaining a material to be ferroelectric in both its solid crystal (SC) and liquid crystal (LC) phases is a great challenge. Moreover, although cholesteric LCs inherently possess the advantage of high fluidity, their ferroelectricity remains unknown. Here, through the reasonable H/F substitution on the fourth position of the phenyl group of the parent nonferroelectric dihydrocholesteryl benzoate, we designed ferroelectric dihydrocholesteryl 4-fluorobenzoate (4-F-BDC), which shows ferroelectricity in both SC and cholesteric LC phases. The fluorination induces a lower symmetric polar P1 space group and a new solid-to-solid phase transition in 4-F-BDC. Beneficial from fluorination, the SC and cholesteric LC phases of 4-F-BDC show clear ferroelectricity, as confirmed by well-shaped polarization-voltage hysteresis loops. The dual ferroelectricity in both SC and cholesteric LC phases of a single material was rarely found. This work offers a viable case for the exploration of the interplay between ferroelectric SC and LC phases and provides an efficient approach for designing ferroelectrics with dual ferroelectricity and cholesteric ferroelectric liquid crystals.

The First Demonstration of Strain-Controlled Periodic Ferroelectric Domains with Superior Piezoelectric Response in Molecular Materials.

Achieving a periodic domain structure in ferroelectric materials to tailor the macroscopic properties or realize new functions has always been a hot topic. However, methods to construct periodic domain structures, such as epitaxial growth, direct writing by scanning tips, and the patterned electrode method, are difficult or inefficient to implement in emerging molecular ferroelectrics, which have the advantages of lightweight, flexibility, biocompatibility, etc. An efficient method for constructing and controlling periodic domain structures is urgently needed to facilitate the development of molecular ferroelectrics in nanoelectronic devices. In this work, it is demonstrated that large-area, periodic and controllable needle-like domain structures can be achieved in thin films of the molecular ferroelectric trimethylchloromethyl ammonium trichlorocadmium (TMCM-CdCl3 ) upon the application of tensile strain. The domain evolution under various tensile strains can be clearly observed, and such processes are accordingly identified. Furthermore, the domain wall exhibits a superior piezoelectric response, with up to fivefold enhancement compared to that of the pristine samples. Such large-area tunable periodic domain structure and abnormally strong piezoresponse are not only of great interests in fundamental studies, but also highly important in the future applications in functional molecular materials.

Remarkable Enhancement of Piezoelectric Performance by Heavy Halogen Substitution in Hybrid Perovskite Ferroelectrics.

Piezoelectric materials that enable electromechanical conversion have great application value in actuators, transducers, sensors, and energy harvesters. Large piezoelectric (d33) and piezoelectric voltage (g33) coefficients are highly desired and critical to their practical applications. However, obtaining a material with simultaneously large d33 and g33 has long been a huge challenge. Here, we reported a hybrid perovskite ferroelectric [Me3NCH2Cl]CdBrCl2 to mitigate and roughly address this issue by heavy halogen substitution. The introduction of a large-size halide element softens the metal-halide bonds and reduces the polarization switching barrier, resulting in excellent piezoelectric response with a large d33 (∼440 pC/N), which realizes a significant optimization compared with that of previously reported [Me3NCH2Cl]CdCl3 (You et al. Science2017, 357, 306-309). More strikingly, [Me3NCH2Cl]CdBrCl2 simultaneously shows a giant g33 of 6215 × 10-3 V m/N, far exceeding those of polymers and conventional piezoelectric ceramics. Combined with simple solution preparation, easy processing of thin films, and a high Curie temperature of 373 K, these attributes make [Me3NCH2Cl]CdBrCl2 promising for high-performance piezoelectric sensors in flexible, wearable, and biomechanical devices.

A Poling-Free Supramolecular Crown Ether Compound with Large Piezoelectricity.

Supramolecular host-guest ferroelectrics based on solution processing are highly desirable because they are generally created with intrinsic piezoelectricity/ferroelectricity and do not need further poling. Poly(vinylidene fluoride) (PVDF) in the electric-active beta phase after stretching/annealing still shows no piezoelectric response unless poled. Although many supramolecular host-guest ferroelectrics have been discovered, their piezoelectricity is relatively small. Based on H/F substitution, we reported a supramolecular host-guest compound [(CF3-C6H4-NH3)(18-crown-6)][TFSA] (CF3-C6H4-NH3 = 4-trifluoromethylanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium) with a remarkable piezoelectric response of 42 pC/N under no poling condition. The introduction of F atoms increases phase transition temperature, polar axes, second harmonic generation (SHG) intensity, and piezoelectric coefficient d33. To our knowledge, such a large piezoelectric performance of [(CF3-C6H4-NH3)(18-crown-6)][TFSA] makes its d33, piezoelectric voltage coefficient g33, and mechanical quality factor Qm the highest among the reported supramolecular host-guest ferroelectric compounds and even larger than the values of PVDF. This work provides inspiration for optimizing piezoelectricity on molecular materials.

Axial-Chiral BINOL Multiferroic Crystals with Coexistence of Ferroelectricity and Ferroelasticity.

Chirality exists everywhere from natural amino acids to particle physics. The introduction of point chirality has recently been shown to be an efficient strategy for the construction of molecular ferroelectrics. In contrast to point chirality, however, axial chirality is rarely used to design ferroelectrics so far. Here, based on optically active 1,1'-bi-2-naphthol (BINOL), which has been applied extensively as a versatile chiral reagent in asymmetric catalysis, chiral recognition, and optics, we successfully design a pair of axial-chiral BINOL multiferroics, (R)-BINOL-DIPASi and (S)-BINOL-DIPASi. They experience a 2F1-type full ferroelectric/ferroelastic phase transition at a high temperature of 362 and 363 K, respectively. Piezoelectric force microscopy and polarization-voltage hysteresis loops demonstrate their ferroelectric domains and domain switching, and polarized light microscopy visualizes the evolution of stripe-shaped ferroelastic domains. The axial-chiral BINOL building block promotes the generation of the polar structure and ferroelectricity, and the organosilicon component increases the rotational energy barrier and thus the phase transition temperature. This work presents the first axial-chiral high-temperature multiferroic crystals, offering an efficient path for designing molecular multiferroics through the introduction of axial chirality.

Biferroelectricity of a homochiral organic molecule in both solid crystal and liquid crystal phases.

Ferroelectricity, existing in either solid crystals or liquid crystals, gained widespread attention from science and industry for over a century. However, ferroelectricity has never been observed in both solid and liquid crystal phases of a material simultaneously. Inorganic ferroelectrics that dominate the market do not have liquid crystal phases because of their completely rigid structure caused by intrinsic chemical bonds. We report a ferroelectric homochiral cholesterol derivative, ß-sitosteryl 4-iodocinnamate, where both solid and liquid crystal phases can exhibit the behavior of polarization switching as determined by polarization-voltage hysteresis loops and piezoresponse force microscopy measurements. The unique long molecular chain, sterol structure, and homochirality of ß-sitosteryl 4-iodocinnamate molecules enable the formation of polar crystal structures with point group 2 in solid crystal phases, and promote the layered and helical structure in the liquid crystal phase with vertical polarization. Our findings demonstrate a compound that can show the biferroelectricity in both solid and liquid crystal phases, which would inspire further exploration of the interplay between solid and liquid crystal ferroelectric phases.

The First Chiro-Inositol Organosilicon Ferroelectric Crystal.

Organosilicons have been used extensively in aerospace, electronics, food, medicine and other fields, due to their low viscosity, hydrophobicity, corrosion resistance, non-toxic, and physiologically inert features. Despite extensive interest, however, organosilicon ferroelectric crystals have never been found. Here, by using the chemical design strategy, we successfully obtained a molecular ferroelectric D-chiro-inositol-SiMe3 with polar P43 symmetry, whose spontaneous polarization can be electrically switchable on thin film. The introduction of organosilicon groups endows the thin films with excellent softness, ductility and flexibility (extremely low hardness of 72.8 MPa and small elastic modulus of 5.04 GPa) that are desirable for biomedical and human-compatible applications. As the first case of organosilicon ferroelectric crystal to date, this work offers a new structural paradigm for molecular ferroelectrics, and highlights their potential for flexible bio-electronic applications.

Chemical design of homochiral heterocyclic organic ferroelectric crystals.

Single component organic ferroelectrics of spirooxazacamphorsultam derivatives, 1-SSR and 1-RRS, exhibit well-defined ferroelectricity (Ps = 2.2 µC cm-2) and piezoelectricity (d33 = 10 pC N-1) below their melting point. More importantly, they possess a low acoustic impedance value of 2.7 × 106 kg s-1 m-2, which is well-matched with body tissues.

Rational Design of Molecular Ferroelectrics with Negatively Charged Domain Walls.

Ferroelectric domains and domain walls are unique characteristics of ferroelectric materials. Among them, charged domain walls (CDWs) are a special kind of peculiar microstructure that highly improve conductivity, piezoelectricity, and photovoltaic efficiency. Thus, CDWs are believed to be the key to ferroelectrics' future application in fields of energy, sensing, information storage, and so forth. Studies on CDWs are one of the most attractive directions in conventional inorganic ferroelectric ceramics. However, in newly emerged molecular ferroelectrics, which have advantages such as lightweight, easy preparation, simple film fabrication, mechanical flexibility, and biocompatibility, CDWs are rarely observed due to the lack of free charges. In inorganic ferroelectrics, doping is a traditional method to induce free charges, but for molecular ferroelectrics fabricated by solution processes, doping usually causes phase separation or phase transition, which destabilizes or removes ferroelectricity. To realize stable CDWs in molecular systems, we designed and synthesized an n-type molecular ferroelectric, 1-adamantanammonium hydroiodate. In this compound, negative charges are induced by defects in the I- vacancy, and CDWs can be achieved. Nanometer-scale CDWs that are stable at temperatures as high as 373 K can be "written" precisely by an electrically biased metal tip. More importantly, this is the first time that the charge diffusion of CDWs at variable temperatures has been investigated in molecular ferroelectrics. This work provides a new design strategy for n-type molecular ferroelectrics and may shed light on their future applications in flexible electronics, microsensors, and so forth.

An unprecedented azobenzene-based organic single-component ferroelectric.

Organic single-component ferroelectrics, as an important class of metal-free ferroelectrics, are highly desirable because of their easy processing, mechanical flexibility, and biocompatibility. However, although nearly 50 years have passed since the discovery of photochromism in azobenzene-doped cholesteric liquid crystals, ferroelectricity has never been found in azobenzene-based crystals. Here, we use an amino group to substitute a fluorine atom of 2,2',4,4',6,6'-hexafluoroazobenzene, which successfully introduces ferroelectricity into 2-amino-2',4,4',6,6'-pentafluoroazobenzene (APFA). APFA shows an extremely high Curie temperature (T c) of 443 K, which is outstanding among single-component ferroelectrics. It also exhibits an indirect optical band gap of 2.27 eV as well as photoisomerization behavior between the trans-form and the cis-form triggered by pedal motion. To our knowledge, APFA is the first azobenzene-based ferroelectric crystal. This work opens an avenue to design excellent single-component ferroelectrics and will inspire the exploration of azobenzene-based ferroelectrics for promising applications in biofriendly ferroelectric devices.

Homochiral Multiferroic Cyanido-Bridged Dimetallic Complexes Assembled by C-F⋠⋠⋠K Interactions.

Cyanido-bridged dimetallic complexes are attracting attention due to their varied structures and properties. However, homochiral cyanido-bridged dimetallic complexes are rare, and making them ferroelectric is a great challenge. Introducing C-F⋅⋅⋅K interactions between the guest chiral cations and the host [KFe(CN)6 ]2- framework, gives three-dimensional cyanido-bridged dimetallic multiferroics, [R- and S-3-fluoropyrrolidinium]2 [KFe(CN)6 ] (R- and S-3-FPC). The mirror-symmetric vibrational circular dichroism (VCD) signal shows their enantiomeric nature. R- and S-3-FPC crystallize in the same chiral-polar space group P21 at 298 K. Piezoresponse force microscopy (PFM), polarizing optical microscopy, and temperature-dependent second-harmonic generation (SHG) measurements show their multiferroic properties (the coexistence of ferroelectricity and ferroelasticity), in line with the Aizu notation of 222F2. R-3-FPC shows excellent ferroelectricity with saturated polarization up to 9.4 µC cm-2 .

Unprecedented Ferroelectricity and Ferromagnetism in a Cr2+ -Based Two-Dimensional Hybrid Perovskite.

Organic-inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two-dimensional Cr2+ -based OIHP, [3,3-difluorocyclobutylammonium]2 CrCl4 ([DFCBA]2 CrCl4 ), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 µC cm-2 . It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices.

Domain memory effect in the organic ferroics.

Shape memory alloys have been used extensively in actuators, couplings, medical guide wires, and smart devices, because of their unique shape memory effect and superelasticity triggered by the reversible martensitic phase transformations. For ferroic materials, however, almost no memory effects have been found for their ferroic domains after reversible phase transformations. Here, we present a pair of single-component organic enantiomorphic ferroelectric/ferroelastic crystals, (R)- and (S)-N-3,5-di-tert-butylsalicylidene-1-(1-naphthyl)ethylamine SA-NPh-(R) and SA-NPh-(S). It is notable that not only can their ferroic domain patterns disappear and reappear during reversible thermodynamic phase transformations, but they can also disappear and reappear during reversible light-driven phase transformations induced by enol-keto photoisomerization, both of which are from P1 to P21 polar space groups. Most importantly, the domain patterns are exactly the same in the initial and final states, demonstrating the existence of a memory effect for the ferroic domains in SA-NPh-(R) and SA-NPh-(S). As far as we are aware, the domain memory effect triggered by both thermodynamic and light-driven ferroelectric/ferroelastic phase transformations remains unexplored in ferroic materials. Thermal and optical control of domain memory effect would open up a fresh research field for smart ferroic materials.

A Tibetan adolescent girl suffered frostbite on the journey of pilgrimage: A case report / 中华创伤杂志(英文版)

Frostbite in Southwestern China has been overlooked due to its low incidence, relatively mild temperature and lack of literature published before. However, it needs to be further studied for religious diversity and distinct geomorphology. In this article, we reported an 18-year-old Tibetan girl who suffered from blizzard attack during pilgrimage. Her feet and several fingers showed mummified gangrene upon physical examination with poor movement. She was diagnosed with 3rd to 4th degree of frostbite. The girl was given oral ibuprofen, debridement and other regular treatment daily, but she was eventually amputated due to insufficient thrombolytic management in primary hospital, delayed informing consent in the referral hospital and ethnic conflict between religion and guidelines. This case enriched the experience of managing complex frostbite in Tibetan population and alarms that efforts should be integrated to protect pilgrims and mountaineers in the Tibetan region.

Application of case-based learning combined with role-playing mode in clinical practice teaching for international students in department of dermatology / 中华医学教育探索杂志

Objective:To explore the application value of case-based learning (CBL) combined with role-playing mode in clinical practice teaching for international students in department of dermatology.Methods:International students from Batch 2013 and Batch 2014 of MBBS (Bachelor of Medicine and Bachelor of Surgery, MBBS) Program of Sichuan University were recruited and divided into study and control group respectively. CBL combined with role-playing mode and traditional lecture-based learning (LBL) was adopted in the study group. The control group adopted the traditional LBL only. The points of knowledge gain, degree of interest inspiration, analytical ability and communication skill were assessed within the study group by questionnaire, meanwhile the final-test scores were compared between the study and control groups. SPSS 17.0 was used for t test, and signed rank-sum test of paired design was used for comparison. Results:Within the study group, the points of knowledge gain, degree of interest inspiration, analytical ability and communication skill for CBL combined with role-playing mode[95 (91,100)] were significantly higher than those of LBL [84 (78, 100)], and the final-test scores were significantly higher in study group [(90.23±4.78) points] than those in control group [(82.51±7.57) points] ( P<0.05). Conclusion:Clinical practice teaching for international medical students can be improved with the CBL combined with role-playing mode based on traditional LBL, which is worthy of widely application in future clinical education.