2D Ultrathin Titanium Nitride Nanosheets as Separator Coatings for Li-S Batteries.

Transition metal nitrides (TMNs) are affirmed to be an appealing candidate for boosting the performance of lithium-sulfur (Li-S) batteries due to their excellent conductivity, strong interaction with sulfur species, and the effective catalytic ability for conversion of polysulfides. However, the traditional bulk TMNs are difficult to achieve large active surface area and fast transport channels for electrons/ions simultaneously. Here, a 2D ultrathin geometry of titanium nitride (TiN) is realized by a facile topochemical conversion strategy, which can not only serve as an interconnected conductive platform but also expose abundant catalytic active sites. The ultrathin TiN nanosheets are coated on a commercial separator, serving as a multifunctional interlayer in Li-S batteries for hindering the polysulfide shuttle effect by strong capture and fast conversion of polysulfides, achieving a high initial capacity of 1357 mAh g-1 at 0.1 C and demonstrating a low capacity decay of only 0.046% per cycle over 1000 cycles at 1 C.

Two-Dimensional Atomically Thin Titanium Nitride via Topochemical Conversion.

Titanium nitride as a typical transition metal nitride (TMN) has attracted increasing interest for its fascinating characteristics and widespread applications. However, the synthesis of two-dimensional (2D) atomically thin titanium nitride is still challenging which hinders its further research in electronic and optoelectronic fields. Here, 2D titanium nitride with a large area was prepared via in situ topochemical conversion of the titanate monolayer. The titanium nitride reveals a thickness-dependent metallic-to-semiconducting transition, where the atomically thin titanium nitride with a thickness of ∼1 nm exhibits an n-type semiconducting behavior and a highly sensitive photoresponse and displays photoswitchable resistance by repeated light irradiation. First-principles calculations confirm that the chemisorbed oxygen on the surface of the titanium nitride nanosheet depletes its electrons, while the light irradiation induced desorption of oxygen leads to increased electron doping and hence the conductance of titanium nitride. These results may allow the scalable synthesis of ultrathin TMNs and facilitate their fundamental physics research and next-generation optoelectronic applications.

Synthesis and Self-Assembly of Ultrathin Holey Graphdiyne Nanosheets for Oxygen Reduction Reaction.

Graphdiyne (GDY) is a fascinating graphene-like 2D carbon allotrope comprising sp and sp2 hybridized carbon atoms. However, GDY materials synthesized by solution-phase methods normally come as thick and porous films or amorphous powders with severely disordered stacking modes that obstruct macroscopic applications. Here, a facile and scalable synthesis of ultrathin holey graphdiyne (HGDY) nanosheets is reported via palladium/copper co-catalyzed homocoupling of 1,3,5-triethynylbenzene. The resulting freestanding 2D HGDY self-assembles into 3D foam-like networks which can in situ anchor clusters of palladium atoms on their surfaces. The Pd/HGDY hybrids exhibit high electrocatalytic activity and stability for the oxygen reduction reaction which outperforms that of Pt/C benchmark. Based on the ultrathin graphene-like sheets and their unique 3D interconnected macrostructures, Pd/HGDY holds great promise for practical electrochemical catalysis and energy-related applications.

Studies on improving semen quality and increasing pregnancy chances through the in vitro addition of L-carnitine and coenzyme Q10 to semen in patients with asthenozoospermia.

BACKGROUND: At present, L-carnitine (LC) and coenzyme Q10 (CoQ10), as used clinically to treat male infertility caused by asthenozoospermia (ASZ) is still mainly administered orally, but some patients with ASZ still show no significant improvement in sperm motility and spouse pregnancy rate. Prodom is a device used to assist reproduction, which is temporarily fitted onto the penis to facilitate conception by helping the wife inject a certain drug into the vagina. This study used Prodom-assisted LC/CoQ10 in the treatment of patients with ASZ and evaluated the effect of this method on sperm motility and clinical pregnancy, with the goal of finding a comfortable, low-cost, effective method. RESULTS: During the trial period, 232 cases completed the trial, while 25 cases did not. During in vitro testing, the progressive sperm motility in the LC group, CoQ10 group, LC combined with CoQ10 group, and the semen blank control group was 24.3 ± 4.6% and 38.1 ± 5.1%, 23.0 ± 4.8% and 36.9 ± 4.4%, 28.4 ± 5.0% and 43.8 ± 5.4%, 19.7 ± 4.4% and 26.0 ± 4.9%, respectively. There were statistically significant differences in progressive sperm motility among the groups (all P values < 0.05). The pregnancy rates of the Prodom-assisted LC treatment group, Prodom-assisted CoQ10 treatment group, Prodom-assisted LC combined with CoQ10 treatment group, and oral LC combined with CoQ10 treatment group in the clinical treatment stage were 38.2, 35.4, 57.1, and 30.3%, respectively; the time to conception was 6.1 ± 1.8, 6.2 ± 1.8, 3.4 ± 0.9, and 7.9 ± 2.0, months respectively; and the treatment costs were $2350 ± 457, $2455 ± 434, $1348 ± 411, and $2684 ± 334, respectively. The differences in pregnancy rate, time to conception, and treatment costs among the groups were statistically significant (all P values < 0.05). CONCLUSIONS: The supplementation of in vitro semen with LC/CoQ10 can improve sperm motility. LC/CoQ10 injected into the spouse's vagina with the assistance of a Prodom can increase the pregnancy rate, shorten the time to conception, and reduce the cost of treatment in patients with ASZ. TRIAL REGISTRATION: ChiCTR2000040349 (registry: http://www.chictr.org.cn/ ). Date of registration: November 28, 2020.

RéSUMé: CONTEXTE: À l'heure actuelle, la L-carnitine (LC) et le coenzyme Q10 (CoQ10), tels qu'utilisés en clinique pour traiter l'infertilité masculine due à une asthénozoospermie (AZS), sont encore principalement administrés par voie orale, mais certains patients atteints d'AZS ne montrent pas toujours d'amélioration significative de la motilité des spermatozoïdes, ni de grossesse chez la conjointe. Prodom™ est. un dispositif utilisé pour aider à la reproduction, qui est. temporairement installé sur le pénis pour faciliter la conception en aidant la femme à injecter certains médicaments dans le vagin. Cette étude a utilisé une association CL + CoQ10 assistée par Prodom™ pour traiter des patients atteints d'AZS et a évalué l'effet de cette méthode sur la mobilité des spermatozoïdes et la grossesse clinique, dans le but de trouver une méthode confortable, peu coûteuse et efficace. RéSULTATS: Au cours de cet essai thérapeutique, 232 cas sont allés au bout de l'étude, alors que 25 se sont arrêtés. Au cours des tests in vitro, la mobilité progressive des spermatozoïdes dans le groupe LC, le groupe CoQ10, le groupe CL + CoQ10 et dans le groupe témoin de sperme, était respectivement de 24,3 ± 4,6% et 38,1 ± 5,1%, de 23,0 ± 4,8% et 36,9 ± 4,4%, de 28,4 ± 5,0% et 43,8 ± 5,4%, et de 19,7 ± 4,4% et 26,0 ± 4,9%. La mobilité progressive des spermatozoïdes était significativement différentes entre les groupes (toutes les valeurs de P < 0,05). Les taux de grossesse dans le groupe traité par LC assistée par Prodom™, dans le groupe traité par CoQ10 assisté par Prodom™, dans le groupe traité par une association CL + CoQ10 assistée par Prodom™, et dans le groupe traité cliniquement par CL par voie orale associée au CoQ10, étaient respectivement de 38,2%, 35,4%, 57,1% et 30,3%; le délai de conception était respectivement de 6,1 ± 1,8, 6,2 ± 1,8, 3,4 ± 0,9 et 7,9 ± 2,0, mois; et les coûts de traitement étaient respectivement de 2350 ± 457 $, 2455 ± 434 $, 1348 ± 411 $ et 2684 ± 334 $. Les différences dans le taux de grossesse, le délai de conception et les coûts de traitement entre les groupes étaient statistiquement significatives (toutes les valeurs de P < 0,05). CONCLUSIONS: La supplémentation en LC/CoQ10 du sperme in vitro peut améliorer la mobilité des spermatozoïdes. L'association LC + CoQ10 injectée dans le vagin de la conjointe avec l'aide d'un Prodom™ peut augmenter le taux de grossesse, raccourcir le délai de conception et réduire le coût du traitement chez les patientes atteints d'AZS. Numéro d'enregistrement de l'essai ChiCTR2000040349 (registre: http://www.chictr.org.cn/ ). Date d'enregistrement: 28 novembre 2020.

An investigation into the effects of soil and fastener-freezing on ground vibrations induced by high-speed train in frozen regions.

With the expansion of high-speed railway network in the world, it is inevitable for railways to pass through seasonal frozen regions. Since in a seasonal frozen region the ground can have significantly different mechanical properties between the freezing season and the warm season, train-induced ground vibration is also season-dependent but it has not received enough attention up to now. This paper gives an investigation into the effects of soil and fastener-freezing on ground vibrations induced by high-speed train in frozen regions. Based on the well-established relationships between soil mechanical properties and freezing temperature, a frozen ground is shown to be still represented by a layered ground and therefore, previously developed models for predicting ground vibration generated by a train running along a track resting on a layered ground can be readily applied. The effects of low temperature on the dynamical properties of fasteners are also considered. Results show that, due to the increased Young's modulus at freezing condition, the vibration level of a frozen ground near the track is lower than that of the non-frozen counterpart. However, well away from the track, the vibration level of the frozen ground is much stronger than that of the non-frozen one, mainly due to the much-reduced loss factor of the frozen ground, which results in slower attenuation of vibration with propagating distance. Results also show that, the difference in ground vibration between a frozen ground and its non-frozen counterpart is mainly caused by freezing of the ground. The emphasis of this study lies in making clear the characteristics of train-induced ground vibration in frozen regions and the differences between frozen and non-frozen regions, providing some new fundamental insights about this practical problem, which have significant engineering guidance and application value.

Experimental Study on Triaxial Compressive Mechanical Properties of Polypropylene Fiber Coral Seawater Concrete.

In order to study the mechanical properties of polypropylene fiber all-coral seawater concrete in triaxial compression, 36 specimens were developed and constructed for triaxial compression load testing employing confining pressure value (0, 6, 12, 18 MPa) and polypropylene fiber admixture (1 kg·m-3, 2 kg·m-3, 3 kg·m-3) as variation parameters. The test observed the failure mode of the specimen and obtained the stress-strain curve of the whole process of its force damage failure. An in-depth analysis of polypropylene fiber all-coral seawater concrete's peak stress, peak strain, initial elastic modulus, axial deflection, energy dissipation, ductility, and damage evolution process was carried out based on the experimental data. The test findings indicated that the best effect on the deformation properties of polypropylene fiber all-coral seawater concrete is obtained when 3 kg·m-3 of polypropylene fiber is blended. Under triaxial compression, the correct number of polypropylene fibers may significantly enhance the peak stress, peak strain, ductility, and elastic modulus of polypropylene fiber all-coral seawater concrete, therefore enhancing the brittle characteristics of coral concrete. During the triaxial surround pressure test, the confining pressure value and polypropylene fiber coupling effect delayed the appearance of initial damage in polypropylene fiber complete coral seawater concrete specimens, slowed the development of damage, and reduced the degree of damage to the specimens.

Failure Criteria and Constitutive Relationship of Lightweight Aggregate Concrete under Triaxial Compression.

This paper investigates the compression behavior and failure criteria of lightweight aggregate concrete (LAC) under triaxial loading. A total of 156 specimens were tested for three parameters: concrete strength, lateral confining pressure and aggregate immersion time, and their effects on the failure mode of LAC and the triaxial stress-strain relationship of LAC is studied. The research indicated that, as the lateral constraint of the specimen increases, the failure patterns change from vertical splitting failure to oblique shearing failure and then to indistinct traces of damage. The stress-strain curve of LAC specimens has an obvious stress plateau, and the curve no longer appears downward when the confining pressure exceeds 12 MPa. According to the experimental phenomenon and test data, the failure criterion was examined on the Mohr-Coulomb theory, octahedral shear stress theory and Rendulic plane stress theory, which well reflects the behavior of LAC under triaxial compression. For the convenience of analysis and application, the stress-strain constitutive models of LAC under triaxial compression are recommended, and these models correlate well with the test results.

Self-assembly and photoinduced fabrication of conductive nanographene wires on boron nitride.

Manufacturing molecule-based functional elements directly at device interfaces is a frontier in bottom-up materials engineering. A longstanding challenge in the field is the covalent stabilization of pre-assembled molecular architectures to afford nanodevice components. Here, we employ the controlled supramolecular self-assembly of anthracene derivatives on a hexagonal boron nitride sheet, to generate nanographene wires through photo-crosslinking and thermal annealing. Specifically, we demonstrate µm-long nanowires with an average width of 200 nm, electrical conductivities of 106 S m-1 and breakdown current densities of 1011 A m-2. Joint experiments and simulations reveal that hierarchical self-assembly promotes their formation and functional properties. Our approach demonstrates the feasibility of combined bottom-up supramolecular templating and top-down manufacturing protocols for graphene nanomaterials and interconnects, towards integrated carbon nanodevices.

Effects of unilateral/bilateral amputation of the ischiocavernosus muscle in male rats on erectile function and conception.

BACKGROUND: The ischiocavernosus muscle (ICM) encompasses a pair of short pinnate muscles attached to the pelvic ring. The ICM begins at the ischial tuberosity and ends at the crus of the penis while covering the surface of the crus. According to the traditional view, the contraction of the ICM plays an auxiliary role in penile erection. However, we have previously shown that the ICM plays an important role in penile erection through an indirect method of diagnosing erectile dysfunction (ED) caused by ICM injury by observing the infertility of paired female rats. Since intracavernosal pressure (ICP) is the current gold standard for diagnosing ED, this study aimed to amputate unilaterally/bilaterally the ICM to establish an ED model by detecting the ICP, recording the infertility of matching female rats, and comparing the two methods. RESULTS: Forty sexually mature adult male rats were selected and randomly divided into the following groups: the control group (n = 10), sham operation group (n = 10), unilateral ischiocavernosus muscle (Uni-ICM) amputation group (n = 10), and bilateral ischiocavernosus muscle (Bi-ICM) amputation group (n = 10). Eighty female reproductive rats were randomly assigned to the above groups at a ratio of 2:1. We evaluated the time to conception for the paired female rats and the effects of unilateral/bilateral severing of the ICM on erectile function. The results showed that the baseline and maximum intracavernosal pressure (ICP) in the control group, sham operation group, Uni-ICM amputation group, and Bi-ICM amputation group were 17.44±2.50 mmHg and 93.51±10.78 mmHg, 17.81±2.81 mmHg and 95.07±10.40 mmHg, 16.73±2.11 mmHg and 83.49±12.38 mmHg, and 14.78±2.78 mmHg and 33.57±6.72 mmHg, respectively, immediately postsurgery. The max ICP in the Bi-ICM amputation group was lower than that in the remaining three groups (all P<0.05). The pregnancy rates were 100, 100, 90, and 0% in the control group, sham operation group, Uni-ICM amputation group, and the Bi-ICM amputation group, respectively. The pregnancy rate in the Bi-ICM amputation group was significantly lower than that in the remaining groups (all P<0.05). The time to conception was approximately 7-10 days later in the Uni-ICM amputation group than in the control and sham groups (all P<0.05). CONCLUSIONS: Male rats undergoing Bi-ICM amputation may develop permanent ED, which affects their fertility. In contrast, rats undergoing Uni-ICM amputation may experience transient ED.

RéSUMé: INTRODUCTION: Le muscle Ischiocavernosus (MIC) est une paire de muscles courts attachés à l'anneau pelvien. Elle commence à la tubérosité ischiale et se termine au crus du pénis tout en couvrant la surface de ce dernier. Selon la vision traditionnelle, la contraction du MIC joue un rôle auxiliaire dans l'érection pénienne. Cependant, nos travaux précédents ont montré qu'il joue un rôle important dans l'érection pénienne par une méthode indirecte de diagnostic de la dysfonction érectile (DE) induite par une blessure du MIC en observant l'infertilité des rats femelles appariés. Comme la pression intracaverneuse (PIC) est actuellement l'étalon de référence pour le diagnostic, cette étude visait à amputer unilatéralement/bilatéralement l'ICM pour établir un modèle de DE par détection de l'ICP, par détection de l'infertilité de rats femelles appariés, et par comparaison des deux méthodes. RéSULTATS: Quarante rats mâles adultes sexuellement matures ont été sélectionnés et répartis aléatoirement dansquatre groupes groupe témoin (n = 10), groupe d'opération simulée (n = 10), groupe d'amputation unilatérale du MIC (Uni-MIC) (n = 10), et groupe d'amputation bilatérale du MIC (Bi-MIC) (n = 10). Quatre-vingts rats femelles en période de reproduction ont été réparties de façon aléatoire dans chacun des groupes mentionnés ci-dessus, selon un rapport de 2:1. Nous avons évalué le temps avant la conception des rats femelles appariés et les effets de l'amputation Uni /Bi-MIC sur la fonction érectile. Les résultats ont montré que la pression de base et la PIC maximale dans le groupe témoin, le groupe d'opération simulée, le groupe Uni-MIC et le groupe Bi-MIC étaient respectivement de 17.44 ± 2.50 mmHg et 93.51 ± 10.78 mmHg, 17.81 ± 2.81 mmHg et 95.07 ± 10.40 mmHg, 16.73 ± 2.11 mmHg et 83.49 ± 12.38 mmHg, et 14.78 ± 2.78 mmHg et 33.57 ± 6.72 mmHg, immédiatement après l'opération. La PIC maximale dans le groupe Bi-MIC était inférieure à celles des trois autres groupes (tous P < 0.05). Les taux de grossesse étaient de 90% dans le groupe Uni-MIC et de 0% dans le groupe Bi-MIC. Le taux de grossesse dans le groupe Bi-MIC était significativement plus faible que dans les autres groupes (tous P < 0.05). Le temps de conception a été d'environ 7 à 10 jours plus tard dans le groupe Uni-MIC que dans le groupe témoin et le groupe d'opération simulée (tous P < 0.05). CONCLUSIONS: Les rats mâles subissant une amputation Bi-MIC peuvent développer une DE permanente qui affecte leur fertilité. En revanche, ceux qui subissent une amputation Uni-MIC peuvent connaître des troubles érectiles transitoires.

Relationship between serum total testosterone and prostate volume in aging men.

Total testosterone levels decline with age, while prostate volume and the prevalence of benign prostatic hyperplasia increase with age. We sought to investigate the correlation of serum testosterone levels with prostate volume in aging men. We analyzed clinical data obtained from 416 ostensibly healthy men who underwent routine health check-ups and recruited and collected data from these subjects 4 years later. We analyzed the correlation between prostate volume and relevant factors, as well as the correlation between changes in prostate volume and low testosterone over a 4-year period. Men with low testosterone had significantly larger prostate volume than those in the normal testosterone group (26.86 ± 8.75 vs. 24.06 ± 6.77 P = 0.02), and subjects with low testosterone had significantly higher levels of obesity-related factors, including waist circumference, body mass index, and insulin (all P < 0.001). After adjustment for age, testosterone level was negatively correlated with prostate volume (P = 0.004), and prostate volume and 4-year changes in prostate volume were associated with low testosterone. With increased testosterone level, prostate volume showed a significant linear decreasing trend. These findings provide evidence of the relationship between testosterone and prostate volume. Additional large studies are needed to confirm these preliminary results.

Pattern-Potential-Guided Growth of Textured Macromolecular Films on Graphene/High-Index Copper.

Macromolecular films are crucial functional materials widely used in the fields of mechanics, electronics, optoelectronics, and biology, due to their superior properties of chemical stability, small density, high flexibility, and solution-processing ability. Their electronic and mechanical properties, however, are typically much lower than those of crystalline materials, as the macromolecular films have no long-range structural ordering. The state-of-the-art for producing highly ordered macromolecular films is still facing a great challenge due to the complex interactions between adjacent macromolecules. Here, the growth of textured macromolecular films on a designed graphene/high-index copper (Cu) surface is demonstrated. This successful growth is driven by a patterned potential that originates from the different amounts of charge transfer between the graphene and Cu surfaces with, alternately, terraces and step edges. The textured films exhibit a remarkable improvement in remnant ferroelectric polarization and fracture strength. It is also demonstrated that this growth mechanism is universal for different macromolecules. As meter-scale graphene/high-index Cu substrates have recently become available, the results open a new regime for the production and applications of highly ordered macromolecular films with obvious merits of high production and low cost.

2D self-assembly and electronic characterization of oxygen-boron-oxygen-doped chiral graphene nanoribbons.

Graphene nanoribbons (GNRs), quasi-one-dimensional strips of graphene, exhibit a nonzero bandgap due to quantum confinement and edge effects. In the past decade, different types of GNRs with atomically precise structures have been synthesized by a bottom-up approach and have attracted attention as a novel class of semiconducting materials for applications in electronics and optoelectronics. We report the large-scale, inexpensive growth of high-quality oxygen-boron-oxygen-doped chiral GNRs with a defined structure using chemical vapor deposition. For the first time, a regular 2D self-assembly of such GNRs has been demonstrated, which results in a unique orthogonal network of GNRs. Stable and large-area GNR films with an optical bandgap of ∼1.9 eV were successfully transferred onto insulating substrates. This ordered network structure of semiconducting GNRs holds promise for controlled device integration.

Long-lived charge separation following pump-wavelength-dependent ultrafast charge transfer in graphene/WS2 heterostructures.

Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo-thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the performance of optoelectronic devices, in particular photodetection.

Clinical Efficacy of Prodom-Assisted Urokinase in the Treatment of Male Infertility Caused by Impaired Semen Liquefaction.

PURPOSE: To evaluate the clinical efficacy of prodom in the administration of urokinase in the vagina in couples with impaired semen liquefaction. MATERIALS AND METHODS: Overall, 261 patients with impaired semen liquefaction were randomly divided into prodom-assisted urokinase treatment (PAUT) group (n = 91), syringe-assisted urokinase treatment (SAUT) group (n = 86), and traditional treatment (TT) group (n = 84) in the first stage. If the first stage of treatment failed, other treatment methods were initiated instead and the patients were grouped according to the newer treatment method in the second stage. The pregnancy rate, time-to-conception, and treatment costs were evaluated in each group. RESULTS: In the first stage, the pregnancy rate in the PAUT, SAUT, and TT groups was 69.23%, 29.07%, and 22.62%, respectively; the time-to-conception was 2.66 ± 1.44, 3.69 ± 2.61, and 3.86 ± 3.00 months, respectively; the treatment costs were 658.18 ± 398.40, 666.67 ± 507.50, and 680.56 ± 480.94 $, respectively. The pregnancy rate and time-to-conception were different in the PAUT group compared with those in SAUT and TT groups (all P < 0.05). However, the difference in treatment costs was not significant (P = 0.717). In the second stage, 154 nonpregnant patients were divided into nine treatment groups, and the effects of changing TT to PAUT on the pregnancy rate, time-to-conception, and treatment costs were observed to be different from those of other treatments (all P < 0.05). CONCLUSION: Prodom-assisted urokinase can effectively treat male infertility secondary to impaired semen liquefaction.

Bottom-Up, On-Surface-Synthesized Armchair Graphene Nanoribbons for Ultra-High-Power Micro-Supercapacitors.

Bottom-up-synthesized graphene nanoribbons (GNRs) with excellent electronic properties are promising materials for energy storage systems. Herein, we report bottom-up-synthesized GNR films employed as electrode materials for micro-supercapacitors (MSCs). The micro-device delivers an excellent volumetric capacitance and an ultra-high power density. The electrochemical performance of MSCs could be correlated with the charge carrier mobility within the differently employed GNRs, as determined by pump-probe terahertz spectroscopy studies.

Graphene Nanoribbons: On-Surface Synthesis and Integration into Electronic Devices.

Graphene nanoribbons (GNRs) are quasi-1D graphene strips, which have attracted attention as a novel class of semiconducting materials for various applications in electronics and optoelectronics. GNRs exhibit unique electronic and optical properties, which sensitively depend on their chemical structures, especially the width and edge configuration. Therefore, precision synthesis of GNRs with chemically defined structures is crucial for their fundamental studies as well as device applications. In contrast to top-down methods, bottom-up chemical synthesis using tailor-made molecular precursors can achieve atomically precise GNRs. Here, the synthesis of GNRs on metal surfaces under ultrahigh vacuum (UHV) and chemical vapor deposition (CVD) conditions is the main focus, and the recent progress in the field is summarized. The UHV method leads to successful unambiguous visualization of atomically precise structures of various GNRs with different edge configurations. The CVD protocol, in contrast, achieves simpler and industry-viable fabrication of GNRs, allowing for the scale up and efficient integration of the as-grown GNRs into devices. The recent updates in device studies are also addressed using GNRs synthesized by both the UHV method and CVD, mainly for transistor applications. Furthermore, views on the next steps and challenges in the field of on-surface synthesized GNRs are provided.

Photomodulation of Charge Transport in All-Semiconducting 2D-1D van der Waals Heterostructures with Suppressed Persistent Photoconductivity Effect.

Van der Waals heterostructures (VDWHs), obtained via the controlled assembly of 2D atomically thin crystals, exhibit unique physicochemical properties, rendering them prototypical building blocks to explore new physics and for applications in optoelectronics. As the emerging alternatives to graphene, monolayer transition metal dichalcogenides and bottom-up synthesized graphene nanoribbons (GNRs) are promising candidates for overcoming the shortcomings of graphene, such as the absence of a bandgap in its electronic structure, which is essential in optoelectronics. Herein, VDWHs comprising GNRs onto monolayer MoS2 are fabricated. Field-effect transistors (FETs) based on such VDWHs show an efficient suppression of the persistent photoconductivity typical of MoS2 , resulting from the interfacial charge transfer process. The MoS2 -GNR FETs exhibit drastically reduced hysteresis and more stable behavior in the transfer characteristics, which is a prerequisite for the further photomodulation of charge transport behavior within the MoS2 -GNR VDWHs. The physisorption of photochromic molecules onto the MoS2 -GNR VDWHs enables reversible light-driven control over charge transport. In particular, the drain current of the MoS2 -GNR FET can be photomodulated by 52%, without displaying significant fatigue over at least 10 cycles. Moreover, four distinguishable output current levels can be achieved, demonstrating the great potential of MoS2 -GNR VDWHs for multilevel memory devices.

The underlying mechanism of metabolic syndrome on benign prostatic hyperplasia and prostate volume.

OBJECTIVE: To investigate the potential mechanism of the effect of metabolic syndrome (MetS) on prostate volume (PV) and the risk of benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) and the relationships of MetS and the major pathogenic factors of MetS with the clinical progression of BPH/LUTS in older Chinese men. SUBJECTS AND METHODS: We analyzed clinical data obtained from 506 ostensibly healthy men who underwent routine health check-ups and recruited 415 subjects from a group of previously studied men after 4 years. We evaluated the associations of major pathological factors of MetS, including insulin resistance, subclinical inflammatory state, and sex hormone changes, with PV, the risk of BPH and the clinical progression of BPH/LUTS by using multiple linear regression and logistic regression. RESULTS: After adjustment for age, insulin, HOMA (homeostatic model assessment) index, leptin, resistin, adiponectin, C-reactive protein, tumor necrosis factor-α (TNF-α), sex hormone-binding globulin, and testosterone levels were significantly associated with PV (all P < .05), and in the age-adjusted logistic regression model, positive associations of resistin and TNF-α with BPH/LUTS were found (OR, 1.662, P = .007 and OR, 1.044, P < .001, respectively). Predictors of BPH/LUTS clinical progression were significantly correlated with MetS and TNF-α. The group with higher TNF-α levels had a higher rate of newly diagnosed BPH (9.5% vs 19.1%, P = .006) and a greater increase in PV levels (0.61 ± 0.08 vs 1.09 ± 0.35 cm3 , P <.001) after 4 years. CONCLUSIONS: MetS and its pathological factors were associated with an increased PV and an increased risk of BPH/LUTS that is more prone to clinical progression. TNF-α may serve as an early biological indicator to identify which patients with BPH/LUTS are at higher risk of unfavorable outcomes.

Charge transport mechanism in networks of armchair graphene nanoribbons.

In graphene nanoribbons (GNRs), the lateral confinement of charge carriers opens a band gap, the key feature that enables novel graphene-based electronics. Despite great progress, reliable and reproducible fabrication of single-ribbon field-effect transistors (FETs) is still a challenge, impeding the understanding of the charge transport. Here, we present reproducible fabrication of armchair GNR-FETs based on networks of nanoribbons and analyze the charge transport mechanism using nine-atom wide and, in particular, five-atom-wide GNRs with large conductivity. We show formation of reliable Ohmic contacts and a yield of functional FETs close to unity by lamination of GNRs to electrodes. Modeling the charge transport in the networks reveals that transport is governed by inter-ribbon hopping mediated by nuclear tunneling, with a hopping length comparable to the physical GNR length. Overcoming the challenge of low-yield single-ribbon transistors by the networks and identifying the corresponding charge transport mechanism is a key step forward for functionalization of GNRs.

Hysteresis in graphene nanoribbon field-effect devices.

Hysteresis in the current response to a varying gate voltage is a common spurious effect in carbon-based field effect transistors. Here, we use electric transport measurements to probe the charge transport in networks of armchair graphene nanoribbons with a width of either 5 or 9 carbon atoms, synthesized in a bottom-up approach using chemical vapor deposition. Our systematic study on the hysteresis of such graphene nanoribbon transistors, in conjunction with temperature-dependent transport measurements shows that the hysteresis can be fully accounted for by trapping/detrapping carriers in the SiO2 layer. We extract the trap densities and depth, allowing us to identify shallow traps as the main origin of the hysteresis effect.