Cascaded compression of size distribution of nanopores in monolayer graphene.

Monolayer graphene with nanometre-scale pores, atomically thin thickness and remarkable mechanical properties provides wide-ranging opportunities for applications in ion and molecular separations1, energy storage2 and electronics3. Because the performance of these applications relies heavily on the size of the nanopores, it is desirable to design and engineer with precision a suitable nanopore size with narrow size distributions. However, conventional top-down processes often yield log-normal distributions with long tails, particularly at the sub-nanometre scale4. Moreover, the size distribution and density of the nanopores are often intrinsically intercorrelated, leading to a trade-off between the two that substantially limits their applications5-9. Here we report a cascaded compression approach to narrowing the size distribution of nanopores with left skewness and ultrasmall tail deviation, while keeping the density of nanopores increasing at each compression cycle. The formation of nanopores is split into many small steps, in each of which the size distribution of all the existing nanopores is compressed by a combination of shrinkage and expansion and, at the same time as expansion, a new batch of nanopores is created, leading to increased nanopore density by each cycle. As a result, high-density nanopores in monolayer graphene with a left-skewed, short-tail size distribution are obtained that show ultrafast and ångström-size-tunable selective transport of ions and molecules, breaking the limitation of the conventional log-normal size distribution9,10. This method allows for independent control of several metrics of the generated nanopores, including the density, mean diameter, standard deviation and skewness of the size distribution, which will lead to the next leap in nanotechnology.

Ultralow contact resistance between semimetal and monolayer semiconductors.

Advanced beyond-silicon electronic technology requires both channel materials and also ultralow-resistance contacts to be discovered1,2. Atomically thin two-dimensional semiconductors have great potential for realizing high-performance electronic devices1,3. However, owing to metal-induced gap states (MIGS)4-7, energy barriers at the metal-semiconductor interface-which fundamentally lead to high contact resistance and poor current-delivery capability-have constrained the improvement of two-dimensional semiconductor transistors so far2,8,9. Here we report ohmic contact between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where the MIGS are sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a contact resistance of 123 ohm micrometres and an on-state current density of 1,135 microamps per micrometre on monolayer MoS2; these two values are, to the best of our knowledge, the lowest and highest yet recorded, respectively. We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS2, WS2 and WSe2. Our reported contact resistances are a substantial improvement for two-dimensional semiconductors, and approach the quantum limit. This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling and extending Moore's law.

Domestication and selection footprints in Persian walnuts (Juglans regia).

Walnut (Juglans) species are economically important hardwood trees cultivated worldwide for both edible nuts and high-quality wood. Broad-scale assessments of species diversity, evolutionary history, and domestication are needed to improve walnut breeding. In this study, we sequenced 309 walnut accessions from around the world, including 55 Juglans relatives, 98 wild Persian walnuts (J. regia), 70 J. regia landraces, and 86 J. regia cultivars. The phylogenetic tree indicated that J. regia samples (section Dioscaryon) were monophyletic within Juglans. The core areas of genetic diversity of J. regia germplasm were southwestern China and southern Asia near the Qinghai-Tibet Plateau and the Himalayas, and the uplift of the Himalayas was speculated to be the main factor leading to the current population dynamics of Persian walnut. The pattern of genomic variation in terms of nucleotide diversity, linkage disequilibrium, single nucleotide polymorphisms, and insertions/deletions revealed the domestication and selection footprints in Persian walnut. Selective sweep analysis, GWAS, and expression analysis further identified two transcription factors, JrbHLH and JrMYB6, that influence the thickness of the nut diaphragm as loci under selection during domestication. Our results elucidate the domestication and selection footprints in Persian walnuts and provide a valuable resource for the genomics-assisted breeding of this important crop.

Association between Impaired Renal Function and Subclinical Myocardial Dysfunction in Patients with Heart Failure with Preserved Ejection Fraction: Assessment Using Noninvasive Pressure-Strain Loop.

INTRODUCTION: The objective of this study was to evaluate the abnormal myocardial function in HFpEF patients with renal dysfunction (RD) and investigate the relationship between renal function and myocardial mechanical characteristics in patients with HFpEF. METHODS: 134 patients with HFpEF and 32 control subjects were enrolled in our study. Clinical and echocardiography data were collected for offline analysis. Global work index (GWI), global constructive work (GCW), global waste work (GWW), and global work efficiency (GWE) were measured after noninvasive pressure-strain loop analysis. Univariate and multivariate analyses were used to determine the correlation between renal function and myocardial function in patients with HFpEF. RESULTS: In comparison to control subjects, patients with HFpEF tend to have higher GWW (78 [50-115] vs. 108 [65-160] mm Hg%, p < 0.05) and lower GWE (96 [95-97] vs. 95 [92-96] %, p < 0.05), while left ventricular ejection fraction (65.5 ± 3.3 vs. 64.3 ± 4.6%, p < 0.05) was comparable between them. Besides, increased GWW (86 [58-152] vs. 125 [94-187] mm Hg%, p < 0.05) and decreased GWE (96 [93-97] vs. 94 [92-96] %, p < 0.05) were detected in patients with RD compared to those with normal renal function. An independent correlation was found between estimated glomerular filtration rate and GWW after multivariate analysis. DISCUSSION/CONCLUSION: More severely impaired myocardial function was detected in HFpEF patients with RD compared to those with normal renal function. Estimated glomerular filtration rate was independently correlated to GWW in patients with HFpEF.

Designing artificial two-dimensional landscapes via atomic-layer substitution.

Technology advancements in history have often been propelled by material innovations. In recent years, two-dimensional (2D) materials have attracted substantial interest as an ideal platform to construct atomic-level material architectures. In this work, we design a reaction pathway steered in a very different energy landscape, in contrast to typical thermal chemical vapor deposition method in high temperature, to enable room-temperature atomic-layer substitution (RT-ALS). First-principle calculations elucidate how the RT-ALS process is overall exothermic in energy and only has a small reaction barrier, facilitating the reaction to occur at room temperature. As a result, a variety of Janus monolayer transition metal dichalcogenides with vertical dipole could be universally realized. In particular, the RT-ALS strategy can be combined with lithography and flip-transfer to enable programmable in-plane multiheterostructures with different out-of-plane crystal symmetry and electric polarization. Various characterizations have confirmed the fidelity of the precise single atomic layer conversion. Our approach for designing an artificial 2D landscape at selective locations of a single layer of atoms can lead to unique electronic, photonic, and mechanical properties previously not found in nature. This opens a new paradigm for future material design, enabling structures and properties for unexplored territories.

Predictive Value and Immunological Role of the HSPA5 Gene in Cervical Cancer.

Cervical cancer (CC) ranks fourth among women's malignancies worldwide and seriously affects women's health. HSPA5 is a heat shock protein, also known as glucose regulatory protein 78 (GRP78). Upregulation of HSPA5 has been reported to be closely associated with multiple types of tumors. However, the specific role of HSPA5 in cervical cancer has not been discovered. In our study, we explored the prognostic value of HSPA5 in CC. Here, we analyzed the (TCGA) and (UCSC) databases, the analysis of HSPA5 in many tumors types was conducted with the "wilcox. test" method. A False Discovery Rate (FDR) value < 0.05 and Log2 | (fold change, FC) |> 1 were set as the cutoffs. "*", "**", and "***" indicate FDR < 0.05, < 0.01, and < 0.001, respectively, and further used human cervical cancer cells for q-PCR and western blotting detection. q-PCR and western blotting results showed that HSPA5 was highly expressed in cervical cancer cells, while it was expressed at low levels in normal cells (P < 0.05).We also analyzed the immunohistochemical data. immunohistochemical analysis results showed that HSPA5 was highly expressed in human cervical cancer, while it was expressed at low levels in normal tissues (P < 0.05). Analysis in TCGA-UCSC showed that the proportion of G3 in the group with high expression of HSPA5 was relatively high (P < 0.05). Enrichment analysis and survival analysis showed that the increased expression of HSPA5 in cervical cancer was related to the survival of CC and was involved in the regulation of biological behavior and molecular signaling pathways of cervical cancer. The correlation analysis of immune checkpoint and immune infiltration showed that HSPA5 was involved in the regulation of immune process of cervical cancer (P < 0.05). Drug sensitivity correlation analysis showed that HSPA5 was a sensitive target for tumor drugs (P < 0.05). In brief, those results suggest that HSPA5 can act as an oncogene of CC development and can serve as an effective predictive biomarker in cervical cancer.

A double-emission molecularly imprinted ratiometric fluorescent sensor based on carbon quantum dots and fluorescein isothiocyanate for visual detection of p-nitroaniline.

A novel molecularly imprinted ratiometric fluorescent sensor CQDs@MIP/FITC@SiO2 for the detection of p-nitroaniline (p-NA) was constructed through the mixture of CQDs@MIP and FITC@SiO2 in the ratio of 1:1 (VCQDs@MIP:VFITC@SiO2). The polymers of CQDs@MIP and FITC@SiO2 were prepared by sol-gel method and reversed-phase microemulsion method, respectively. CQDs@MIP was used as the auxiliary response signal and FITC@SiO2 was used as the reference enhancement signal. The signal was measured at excitation/emission wavelengths of 365/438, 512 nm. The sensor showed good linearity in the concentration range 0.14-40.00 µM (R2 = 0.998) with a detection limit of 0.042 µM for p-NA. The color change of "blue-cyan-green" could be observed by the naked eye under 365 nm UV light, thus realizing the visual detection of p-NA. The sensor presented comparable results compared with high-performance liquid chromatography (HPLC) method for the detection of p-NA in hair dye paste and aqueous samples with recoveries of 96.8-103.7% and 95.8-104.4%, respectively. It was demonstrated that the constructed sensor possesses the advantages of simplicity, excellent selectivity, superior sensitivity, and outstanding stability.

Molecularly imprinted ratiometric fluorescence sensor for visual detection of 17ß-estradiol in milk: A generalized strategy toward imprinted ratiometric fluorescence construction.

17ß-Estradiol (E2) is the typical endocrine disruptor of steroidal estrogens and is widely used in animal husbandry and dairy processing. In the environment, even lower concentrations of E2 can cause endocrine dysfunction in organisms. Herein, we have developed a novel molecularly imprinted ratiometric fluorescent sensor based on SiO2-coated CdTe quantum dots (CdTe@SiO2) and 7-hydroxycoumarin with a post-imprint mixing strategy. The sensor selectively detected E2 in aqueous environments due to its two fluorescent signals with a self-correction function. The sensor has been successfully used for spiking a wide range of real water and milk samples. The results showed that the sensor exhibited good linearity over the concentration range 0.011-50 µg/L, obtaining satisfactory recoveries of 92.4-110.6% with precisions (RSD) < 2.5%. Moreover, this sensor obtained an ultra-low detection limit of 3.3 ng/L and a higher imprinting factor of 13.66. By using estriol (E3), as a supporting model, it was confirmed that a simple and economical ratiometric fluorescent construction strategy was provided for other hydrophobic substances.

Revealing Variable Dependences in Hexagonal Boron Nitride Synthesis via Machine Learning.

Wafer-scale monolayer two-dimensional (2D) materials have been realized by epitaxial chemical vapor deposition (CVD) in recent years. To scale up the synthesis of 2D materials, a systematic analysis of how the growth dynamics depend on the growth parameters is essential to unravel its mechanisms. However, the studies of CVD-grown 2D materials mostly adopted the control variate method and considered each parameter as an independent variable, which is not comprehensive for 2D materials growth optimization. Herein, we synthesized a representative 2D material, monolayer hexagonal boron nitride (hBN), on single-crystalline Cu (111) by epitaxial chemical vapor deposition and varied the growth parameters to regulate the hBN domain sizes. Furthermore, we explored the correlation between two growth parameters and provided the growth windows for large flake sizes by the Gaussian process. This new analysis approach based on machine learning provides a more comprehensive understanding of the growth mechanism for 2D materials.

Interposition of acellular amniotic membrane at the tendon to bone interface would be better for healing than overlaying above the tendon to bone junction in the repair of rotator cuff injury.

PURPOSE: The retear rate of rotator cuff (RC) after surgery is high, and the rapid and functional enthesis regeneration remains a challenge. Whether acellular amniotic membrane (AAM) helps to promote the healing of tendon to bone and which treatment is better are both unclear. The study aims to investigate the effect of AAM on the healing of RC and the best treatment for RC repair. METHODS: Thirty-three Sprague Dawley rats underwent RC transection and repair using microsurgical techniques and were randomly divided into the suturing repair only (SRO) group (n = 11), the AAM overlaying (AOL) group (n = 11), and the AAM interposition (AIP) group (n = 11), respectively. Rats were sacrificed at 4 weeks, then examined by subsequent micro-CT, and evaluated by histologic and biomechanical tests. The statistical analyses of one-way ANOVA or Kruskal-Wallis test were performed using with SPSS 23.0. A p < 0.05 was considered a significant difference. RESULTS: AAM being intervened between tendon and bone (AIP group) or overlaid over tendon to bone junction (AOL group) in a rat model, promoted enthesis regeneration, increased new bone and cartilage generation, and improved collagen arrangement and biomechanical properties in comparison with suturing repair only (SRO group) (AOL vs. SRO, p < 0.001, p = 0.004, p = 0.003; AIP vs. SRO, p < 0.001, p < 0.001, p < 0.001). Compared with the AOL group, the AIP group had better results in micro-CT evaluation, histological score, and biomechanical testing (p = 0 0.039, p = 0.011, p = 0.003, respectively). CONCLUSION: In the RC repair model, AAM enhanced regeneration of the tendon to bone junction. This regeneration was more effective when the AAM was intervened at the tendon to bone interface than overlaid above the tendon to bone junction.

RFX2 promotes tumor cell stemness through epigenetic regulation of PAF1 in spinal ependymoma.

PURPOSE: Spinal ependymoma (SE) is a rare tumor that is most commonly low-grade and tends to recur when complete tumor resection is not feasible. We investigated the molecular mechanism induces stem cell features in SE. METHODS: Immunohistochemical staining was conducted to analyze the expression of RFX2 in tumor tissues of SE patients at different stages. The expression of tumor stemness markers (Netsin and CD133) was analyzed using western blot analysis and IF, and the efficiency of sphere formation in SE cells was analyzed. The biological activities of SE cells were analyzed by EdU proliferation assay, TUNEL, wound healing, and Transwell assays. The regulatory relationship of RFX2 on PAF1 was verified by ChIP-qPCR and the dual-luciferase assay. SE cells were injected into the spinal cord of nude mice for in vivo assays. RESULTS: RFX2 was higher in the tumor tissues of SE-III patients than in the tumor tissues of SE-I patients. RFX2 knockdown reduced the expression of tumor stemness markers in SE cells and inhibited the sphere formation efficiency. Moreover, RFX2 knockdown ameliorated the malignant progression of SE in nude mice, as manifested by prolonged survival and alleviated SE tumor infiltration. RFX2 bound to the PAF1 promoter to induce its transcription. Overexpression of PAF1 overturned the effects of RFX2 knockdown on stem cell features and biological activities of SE cells, thereby reducing survival in mice. CONCLUSIONS: RFX2 activates PAF1 transcription, which promotes tumor stemness of SE cells and leads to the malignant progression of SE.

The association of three anatomical factors with ulnar-sided wrist pain: a radiological study.

BACKGROUND: Ulnar-sided wrist pain is associated with the development of multiple wrist pathologies. But the anatomical etiologies have not been fully understood. PURPOSE: To determine the association of three anatomical factors with ulnar-sided wrist pain, including ulnar variance (UV), distal ulnar volar angle (DUVA), and pisiform-ulnar distance (PUD). MATERIAL AND METHODS: A total of 64 patients who had ulnar-sided wrist pain associated with training injuries were retrospectively studied. A control group included 64 healthy athletes from the same unit. The UV, DUVA, and PUD of each individual was measured on radiographs. RESULTS: The average UV and DUVA of those in the ulnar-sided pain group were 0.84 mm and 174.65°, respectively; the control group values were 0.39 mm and 175.11°. The differences between the two groups had no statistical significance (P > 0.05). The average PUD of the ulnar-sided wrist pain group was shorter than that of the control group (2.37 cm vs. 2.65 cm); the difference had statistical significance (P < 0.05). PUD had a negative correlation with ulnar-sided pain; it was an anatomical protective factor (odds ratio = 0.01; P < 0.00; 95% confidence interval=0.00-0.05). Both UV and DUVA had no significant correlations with ulnar-sided wrist pain (P > 0.05). CONCLUSION: PUD has a significant correlation with ulnar-sided wrist pain. It is the anatomical protective factor. Both the UV and DUVA have no statistical association with ulnar-sided wrist pain, but we cannot ignore their potential pathogenic effects on wrists, and further studies are needed to confirm the results.

Electrical Control of Chemical Vapor Deposition of Graphene.

Chemical vapor deposition (CVD) is widely used for the efficient growth of low-dimensional materials. The growth mechanism comprises mass and heat transport, gas-phase and surface chemical reactions, and the interaction between the product and the substrate/catalyst. Correspondingly, the controllable parameter space is conventionally focused on the mass flow of each component, the temperature of the reaction chamber and the substrate, and the material and structure of the substrate/catalyst. Here, we report that applying an electric field between the copper substrate and a counter electrode has significant impacts on the growth of graphene. Electrochemical effect and ionic collision effect are observed in different conditions. With the assistance of negative and positive voltages applied on the growth substrate, selective growth and rapid growth of clean graphene films are achieved, respectively. We anticipate such electrical control will open up new ways to assist the synthesis of two-dimensional (2D) materials.

Genome-wide association analysis of 101 accessions dissects the genetic basis of shell thickness for genetic improvement in Persian walnut (Juglans regia L.).

BACKGROUND: Understanding the underlying genetic mechanisms that drive phenotypic variations is essential for enhancing the efficacy of crop improvement. Persian walnut (Juglans regia L.), which is grown extensively worldwide, is an important economic tree fruit due to its horticultural, medicinal, and material value. The quality of the walnut fruit is related to the selection of traits such as thinner shells, larger filling rates, and better taste, which is very important for breeding in China. The complex quantitative fruit-related traits are influenced by a variety of physiological and environmental factors, which can vary widely between walnut genotypes. RESULTS: For this study, a set of 101 Persian walnut accessions were re-sequenced, which generated a total of 906.2 Gb of Illumina sequence data with an average read depth of 13.8× for each accession. We performed the genome-wide association study (GWAS) using 10.9 Mb of high-quality single-nucleotide polymorphisms (SNPs) and 10 agronomic traits to explore the underlying genetic basis of the walnut fruit. Several candidate genes are proposed to be involved in walnut characteristics, including JrPXC1, JrWAKL8, JrGAMYB, and JrFRK1. Specifically, the JrPXC1 gene was confirmed to participate in the regulation of secondary wall cellulose thickening in the walnut shell. CONCLUSION: In addition to providing considerable available genetic resources for walnut trees, this study revealed the underlying genetic basis involved in important walnut agronomic traits, particularly shell thickness, as well as providing clues for the improvement of genetic breeding and domestication in other perennial economic crops.

Left atrial strain for predicting recurrence in patients with non-valvular atrial fibrillation after catheter ablation: a single-center two-dimensional speckle tracking retrospective study.

BACKGROUND: Although catheter ablation (CA) is an effective treatment for non-valvular atrial fibrillation (AF), a good many of patients still have a recurrence following post-operation. Prediction of AF recurrence by evaluating left atrial (LA) phase function with speckle tracking echocardiography (STE) may be helpful for risk stratification and clinical management for AF patients. Therefore, the current study aimed to assess the prognostic value of LA strains in non-valvular AF patients after CA. METHODS: A total of 95 non-valvular AF patients (70.5% paroxysmal AF, 56.8% males, mean age 63.2 ± 9.7 years) were included in this retrospective study between October 2019 and August 2020. Transthoracic echocardiography was performed in all the subjects and STE was used to analyze the LA reservoir strain (LASr), LA conduit strain (LAScd) and LA contractile strain (LASct) during different phases before CA. Patients were followed up with until January 2022. The endpoint was AF recurrence. RESULTS: Over a median follow-up period of 26.0 months (interquartile range, 24.7-26.7 months), 26 patients experienced recurrence and 69 stayed in sinus rhythm. Compared with no-recurrence group, maximum volume of LA (LAVmax), minimum volume of LA (LAVmin) and LA volume index (LAVI) were increased in the recurrence group, while LAEF, LASr and LASct were worsened (P < 0.05). Multivariable logistic regression analysis revealed that LASct was an independent predictor of AF recurrence (odds ratio, 0.89; 95% confidence interval (CI), 0.82-0.97; P = 0.007) and receiver operating characteristic (ROC) curve analysis showed an area under the curve of LASct<8% was 0.70 (95% CI, 0.59-0.79; P = 0.0008). CONCLUSIONS: LASct was of independent predictive value of AF recurrence. LA function assessed by STE may contribute to the risk stratification for AF patients and selection of suitable patients for CA.

Development of an unsupervised cycle contrastive unpaired translation network for MRI-to-CT synthesis.

PURPOSE: The purpose of this work is to develop and evaluate a novel cycle-contrastive unpaired translation network (cycleCUT) for synthetic computed tomography (sCT) generation from T1-weighted magnetic resonance images (MRI). METHODS: The cycleCUT proposed in this work integrated the contrastive learning module from contrastive unpaired translation network (CUT) into the cycle-consistent generative adversarial network (cycleGAN) framework to effectively achieve unsupervised CT synthesis from MRI. The diagnostic MRI and radiotherapy planning CT images of 24 brain cancer patients were obtained and reshuffled to train the network. For comparison, the traditional cycleGAN and CUT were also implemented. The sCT images were then imported into a treatment planning system to verify their feasibility for radiotherapy planning. The mean absolute error (MAE), peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM) between the sCT and the corresponding real CT images were calculated. Gamma analysis between sCT- and CT-based dose distributions was also conducted. RESULTS: Quantitative evaluation of an independent test set of six patients showed that the average MAE was 69.62 ± 5.68 Hounsfield Units (HU) for the proposed cycleCUT, significantly (p-value < 0.05) lower than that for cycleGAN (77.02 ± 6.00 HU) and CUT (78.05 ± 8.29). The average PSNR was 28.73 ± 0.46 decibels (dB) for cycleCUT, significantly larger than that for cycleGAN (27.96 ± 0.49 dB) and CUT (27.95 ± 0.69 dB). The average SSIM for cycleCUT (0.918 ± 0.012) was also significantly higher than that for cycleGAN (0.906 ± 0.012) and CUT (0.903 ± 0.015). Regarding gamma analysis, cycleCUT achieved the highest passing rate (97.95 ± 1.24% at the 2%/2 mm criteria and 10% dose threshold) but was not significantly different from the others. CONCLUSION: The proposed cycleCUT could be effectively trained using unaligned image data, and could generate better sCT images than cycleGAN and CUT in terms of HU number accuracy and fine structural details.

Molecularly imprinted probe based on CdTe QDs and magnetic nanoparticles for selective recognition of malachite green in seawater and its sensing mechanisms.

A magnetic molecularly imprinted probe (MMIP@QD) was synthesized by reverse microemulsion method using CdTe QDs, Fe3O4, and molecularly imprinted polymer as the fluorophore, magnetic carrier, and recognition sites, respectively. The nanoparticle was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and vibrating sample magnetometry (VSM). In the optimal experimental condition, fluorescent emission intensity (measured at excitation wavelengths of 350 nm) was quenched linearly with increasing malachite green (MG) concentration from 0.8 to 28.0 µM with LOD of 0.67 µM. Simultaneously, it was observed that the maximum absorption wavelength was blue shifted gradually with the increase of MG concentration. The inner filter effect, static quenching, and band gap transition were interpreted as the mechanisms of fluorescence quenching and wavelength shift. Thermodynamic studies indicated that the quenching reaction proceeded spontaneously. The developed sensor was applied to detect MG in seawater samples. Satisfactory recoveries of MG in spiked seawater ranged from 83.6 to 122.1% with RSD < 1.8%.

Novel electrochemical sensor modified with molecularly imprinted polymers for determination of enrofloxacin in marine environment.

Molecularly imprinted polymers were synthesized by gel-sol method with multi-walled carbon nanotubes as support and enrofloxacin as a template and further modified on the surface of glassy carbon electrode to construct a molecularly imprinted electrochemical sensor. The performance of the imprinted electrochemical sensor was thoroughly investigated by using cyclic voltammetry and differential pulse voltammetry. The influence of imprinted polymers amount, electrolyte pH, and incubation time on the sensor performance was investigated for the detection of enrofloxacin. Under the optimal experimental conditions in a three-electrode system with the modified electrode as the working electrode the differential pulse voltammetry response current of the sensor had a good linear relationship at 0.2 V (vs. saturated calomel reference electrode) with the enrofloxacin concentration within 2.8 pM-28 µM and the limit of detection of the method was 0.9 pM. The competitive interference experiment showed that the imprinted electrochemical sensor could selectively recognize enrofloxacin. The method was applied to analyze spiked natural seawater, fish, and shrimp samples. The recovery was 96.4%-102%, and RSD was less than 4.3% (n = 3), indicating that the proposed imprinted electrochemical sensor was suitable for the determination of trace enrofloxacin in marine environment samples.

Toward an Intelligent Synthesis: Monitoring and Intervening in the Catalytic Growth of Carbon Nanotubes.

The bottom-up approach to directly synthesizing low-dimensional materials with outstanding performance has extended the material basis for the next generation integrated circuit industry. All the low-dimensional semiconductors, metals, dielectrics, and their heterojunctions are very promising bricks to build faster and more efficient chips because of their atomically smooth surface and interfaces. The greatest challenge in the synthesis of nanomaterials is how to precisely control the structure, crystalline orientation, defects, dimensions, etc. In past decades, both the methodology and the mechanism of synthesis have been systematically investigated to improve the controllability. However, few studies focused on sensing the synthesis processes in situ and responding to the synthesis immediately. Here, we propose the concept of intelligent synthesis in which the final product can be automatically fine-controlled by a closed loop including in situ monitoring and real-time interventions. As a model system, a high-temperature-tolerant circuit is fabricated on the single-walled carbon nanotube (SWCNT) growth substrate for sensing and responding to the synthesis processes. As a result, either highly pure semiconducting (s-) SWCNT arrays or metallic-semiconducting (m-s) junction arrays with different junction positions is simply synthesized by programming the responding signal. The intelligent synthesis shows much higher efficiency and controllability compared to conventional methods and will lead to the next leap in nanotechnology.

Effect of sample volume on the sensitivity of lateral flow assays through computational modeling.

Lateral flow assays (LFAs) are extensively used in qualitative detection because of their convenience, low cost, fast results, and ease of operation. However, the sample volume used in a lateral flow assay is usually determined experimentally. We test and find that the flow velocity is influenced by sample volume, using fluorescent microspheres as label particles, when analyte concentration is fixed in a sandwich LFA. A model is developed based on mass-action kinetics and advection-diffusion-reaction equation, combing the conjugate pad and nitrocellulose membrane. The model shows predictions from 10 to 120 µL, and predicts accurately the experimental results from 50 to 120 µL where the fluid can flow to the test line. Over all, the model can provide predictions over a wide range of sample volumes for sensitivity analysis. On the basis of the model, the sensitivity of the LFA can be improved according to the sample volume added in the experiment.