Based on 3D-PDU and clinical characteristics nomogram for prediction of lymph node metastasis and lymph-vascular space invasion of early cervical cancer preoperatively.

PURPOSE: To develop and validate a nomogram based on 3D-PDU parameters and clinical characteristics to predict LNM and LVSI in early-stage cervical cancer preoperatively. MATERIALS AND METHODS: A total of first diagnosis 138 patients with cervical cancer who had undergone 3D-PDU examination before radical hysterectomy plus lymph dissection between 2014 and 2019 were enrolled for this study. Multivariate logistic regression analyses were performed to analyze the 3D-PDU parameters and selected clinicopathologic features and develop a nomogram to predict the probability of LNM and LVSI in the early stage. ROC curve was used to evaluate model differentiation, calibration curve and Hosmer-Lemeshow test were used to evaluate calibration, and DCA was used to evaluate clinical practicability. RESULTS: Menopause status, FIGO stage and VI were independent predictors of LNM. BMI and maximum tumor diameter were independent predictors of LVSI. The predicted AUC of the LNM and LSVI models were 0.845 (95%CI,0.765-0.926) and 0.714 (95%CI,0.615-0.813). Calibration curve and H-L test (LNM groups P = 0.478; LVSI P = 0.783) all showed that the predicted value of the model had a good fit with the actual observed value, and DCA indicated that the model had a good clinical net benefit. CONCLUSION: The proposed nomogram based on 3D-PDU parameters and clinical characteristics has been proposed to predict LNM and LVSI with high accuracy, demonstrating for the first time the potential of non-invasive prediction. The probability derived from this nomogram may have the potential to provide valuable guidance for physicians to develop clinical individualized treatment plans of FIGO patients with early cervical cancer.

SMART Design of a Bulk-Capped Supramolecular Segment for the Assembly into Organic Interdigital Lipid Bilayer-Like (ILB) Nanosheets.

Rational molecular design for the organic nanocrystal morphology still remains a challenge due to the structural diversity and complicated weak intermolecular interactions. In this work, a typical attractor-repulsor molecule N,N-diphenyl-4-(9-phenyl-fluoren-9-yl) phenylamine (TPA-PF) is designed to explore a general assembly strategy for 2D nanocrystals. Via an interdigital lipid bilayer-like (ILB) molecular packing mode, large-sized lamellar 2D nanosheets are obtained with a length:width:thickness ratio as ≈2500:1000:1. The d-spacing of the largest (001) plane is 1.32 nm, which equals to the thickness of a single interdigital stacking layer. The synergetic effect of the attractive supramolecular segment (TPA) and the repulsive bulky group (PF) is supposed to be the critical factor for the ILB packing that leads to the 2D structures. The attractor-repulsor molecule design is expected to be an effective strategy for the growth of 2D nanocrystals based on small organic molecules.

Surface Energy and Surface Stability of Ag Nanocrystals at Elevated Temperatures and Their Dominance in Sublimation-Induced Shape Evolution.

The surface energy and surface stability of Ag nanocrystals (NCs) are under debate because the measurable values of the surface energy are very inconsistent, and the indices of the observed thermally stable surfaces are apparently in conflict. To clarify this issue, a transmission electron microscope is used to investigate these problems in situ with elaborately designed carbon-shell-capsulated Ag NCs. It is demonstrated that the {111} surfaces are still thermally stable at elevated temperatures, and the victory of the formation of {110} surfaces over {111} surfaces on the Ag NCs during sublimation is due to the special crystal geometry. It is found that the Ag NCs behave as quasiliquids during sublimation, and the cubic NCs represent a featured shape evolution, which is codetermined by both the wetting equilibrium at the Ag-C interface and the relaxation of the system surface energy. Small Ag NCs (≈10 nm) no longer maintain the wetting equilibrium observed in larger Ag NCs, and the crystal orientations of ultrafine Ag NCs (≈6 nm) can rotate to achieve further shape relaxation. Using sublimation kinetics, the mean surface energy of Ag NCs at 1073 K is calculated to be 1.1-1.3 J m-2 .

Ultrasound diagnosis of intramural pregnancy.

Intramural pregnancy is a rare type of ectopic pregnancy, where the gestational sac is implanted inside the myometrium instead of the endometrial and fallopian tubes. Preoperative diagnosis remains very difficult. Ultrasonic findings vary according to the anatomical location or duration of pregnancy. In this study, we summarized the ultrasonic characteristics of intramural pregnancy by assessing three cases. We also propose a set of ultrasonic characteristics to facilitate differential diagnosis between intramural pregnancy and other types of ectopic pregnancy.

Role of ultrasound in diagnosing isolated torsion of fallopian tube.

AIM: To summarize the ultrasonic features of isolated fallopian tube torsion (IFTT) by retrospectively analyzing cases presenting at our hospital. METHODS: This analysis was approved by the ethical committee of our hospital. Medical records of surgically proven IFTT patients admitted to our hospital since 2002 were collected. Clinical features and preoperative diagnoses of the patients were analyzed retrospectively. Ultrasonic images were reviewed and characteristics, including location, size, shape, echo and vascularity of the fallopian tube, were summarized. RESULTS: Eleven patients with IFTT were studied. No obvious association was found between the torsion and menstruation cycle. Only four accurate diagnoses were made before the operation. Degrees of torsion ranged 360-2160°. Most of them (9/11, 81.8%) were greater than 720°. Sonograms of the 11 patients could be classified into four types: cystic masses, tube-like structures, heterogeneous masses and whirlpool signs. Cystic masses were the most commonly seen type (4/11, 36.4%), followed by tubular structures (3/11, 27.3%). Whirlpool sign was believed to be the most specific sign in diagnosing IFTT. CONCLUSION: Through review of the authors' experiences, it is possible to diagnose IFTT preoperatively by ultrasound. Sonograms of the IFTT could be divided into four types while clinical significance of this classification requires further confirmation.

Anti-PD-L1 antibody retains antitumour effects while mitigating immunotherapy-related colitis in bladder cancer-bearing mice after CT-mediated intratumoral delivery.

Drug local delivery system that directly supply anti-cancer drugs to the tumor microenvironment (TME) results in excellent tumor control and minimizes side effects associated with the anti-cancer drugs. Immune checkpoint inhibitors (ICIs) have been the mainstay of cancer immunotherapy. However, the systemic administration of ICIs is accompanied by considerable immunotherapy-related toxicity. To explore whether an anti-PD-L1 antibody administered locally via a sustained-release gel-forming carrier retains its effective anticancer function while causing fewer colitis-like side effects, CT, a previously reported depot system, was used to locally deliver an anti-PD-L1 antibody together with curcumin to the TME in bladder cancer-bearing ulcerative colitis model mice. We showed that CT-mediated intratumoral coinjection of an anti-PD-L1 antibody and curcumin enabled sustained release of both the loaded anti-PD-L1 antibody and curcumin, which contributed to substantial anticancer effects with negligible side effects on the colons of the UC model mice. However, although the anti-PD-L1 antibody administered systemically synergized with the CT-mediated intratumoral delivery of curcumin in inhibiting tumour growth, colitis was significantly worsened by intraperitoneal administration of anti-PD-L1 antibody. These findings suggested that CT is a promising agent for the local delivery of anticancer drugs, as it can allow effective anticancer functions to be retained while sharply reducing the adverse side effects associated with the systemic administration of these drugs.

Deep learning and ultrasound feature fusion model predicts the malignancy of complex cystic and solid breast nodules with color Doppler images.

This study aimed to evaluate the performance of traditional-deep learning combination model based on Doppler ultrasound for diagnosing malignant complex cystic and solid breast nodules. A conventional statistical prediction model based on the ultrasound features and basic clinical information was established. A deep learning prediction model was used to train the training group images and derive the deep learning prediction model. The two models were validated, and their accuracy rates were compared using the data and images of the test group, respectively. A logistic regression method was used to combine the two models to derive a combination diagnostic model and validate it in the test group. The diagnostic performance of each model was represented by the receiver operating characteristic curve and the area under the curve. In the test cohort, the diagnostic efficacy of the deep learning model was better than traditional statistical model, and the combined diagnostic model was better and outperformed the other two models (combination model vs traditional statistical model: AUC: 0.95 > 0.70, P = 0.001; combination model vs deep learning model: AUC: 0.95 > 0.87, P = 0.04). A combination model based on deep learning and ultrasound features has good diagnostic value.

Hydrothermal Synthesis of Te Nanosheets: Growth Mechanism and Electrical Property.

Hydrothermal synthesis is a highly efficient way to yield multiform Te nanosheets. However, the growth mechanisms and property discrepancies between different types of Te nanosheets are still unclear. In this paper, we perform an investigation on this issue by monitoring the hydrothermally synthesized Te nanosheets at different growth stages with transmission electron microscopy and electrical tests. Three main types of Te nanosheets and their variants are revealed including trapezoidal and "V"-shaped configurations. It is found that the different types of Te nanosheets dominate at different reaction stages, indicating a sequential growth scenario. Surfactants and surface energy co-determine the growth kinetics, while the crystallographic attachments lead to specifically included angles of 74° and 41° in the "V"-shaped Te nanosheets. The fractions of the three main types of Te nanosheets as a function of reaction time are statistically tracked, and their crystalline structures, interfaces, and preferential growth orientations are uncovered. Moreover, the electrical properties of the Te nanosheets are tested, and the results show an interface-related feature. These findings provide some new insights into the synthesis and property of low-dimensional Te functional materials.

Revealing the alloying and dealloying behaviours in AuAg nanorods by thermal stimulus.

Binary metallic nanocrystals are attractive as they offer an extra degree of freedom for structure and phase modulation to generate synergistic effects and extraordinary properties. However, whether the binary structures and phases at the nanoscale still follow the rules established on the bulk counterparts remains unclear. In this work, AuAg nanorods were used as a sample to probe into this issue. An in situ heating method by combining aberration-corrected transmission electron microscopes with a chip-based heating holder was employed to perform the heating experiments. It was found that the AuAg nanorods, which initially possessed heterostructures, can be designed and engineered to be gradient phase alloys with thermal pulses over 350 °C. Atomic diffusion inside the rod structures did not alter the shape of the rods but provided a route to fine-tune their properties. At higher temperatures, the discrepant sublimation behaviours between Au and Ag lead to dealloying of the nanorods. Durative sublimation of the Ag element can continuously tailor the lengths of the nanorods while concentrating the Au composition simultaneously. Especially, nearly pure Au nanocrystals can be obtained with the depletion of Ag by sublimation. These findings give insights into the nanoscale structure and phase behaviours in binary alloys and provide an alternative way to fine-tune their structure, phase, and properties.

Nomogram based on the O-RADS for predicting the malignancy risk of adnexal masses with complex ultrasound morphology.

OBJECTIVE: The accurate preoperative differentiation of benign and malignant adnexal masses, especially those with complex ultrasound morphology, remains a great challenge for junior sonographers. The purpose of this study was to develop and validate a nomogram based on the Ovarian-Adnexal Reporting and Data System (O-RADS) for predicting the malignancy risk of adnexal masses with complex ultrasound morphology. METHODS: A total of 243 patients with data on adnexal masses with complex ultrasound morphology from January 2019 to December 2020 were selected to establish the training cohort, while 106 patients with data from January 2021 to December 2021 served as the validation cohort. Univariate and multivariate analyses were used to determine independent risk factors for malignant tumors in the training cohort. Subsequently, a predictive nomogram model was developed and validated in the validation cohort. The calibration, discrimination, and clinical net benefit of the nomogram model were assessed separately by calibration curves, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). Finally, we compared this model to the O-RADS. RESULTS: The O-RADS category, an elevated CA125 level, acoustic shadowing and a papillary projection with color Doppler flow were the independent predictors and were incorporated into the nomogram model. The area under the ROC curve (AUC) of the nomogram model was 0.958 (95% CI, 0.932-0.984) in the training cohort. The specificity and sensitivity were 0.939 and 0.893, respectively. This nomogram also showed good discrimination in the validation cohort (AUC = 0.940, 95% CI, 0.899-0.981), with a sensitivity of 0.915 and specificity of 0.797. In addition, the nomogram model showed good calibration efficiency in both the training and validation cohorts. DCA indicated that the nomogram was clinically useful. Furthermore, the nomogram model had higher AUC and net benefit than the O-RADS. CONCLUSION: The nomogram based on the O-RADS showed a good predictive ability for the malignancy risk of adnexal masses with complex ultrasound morphology and could provide help for junior sonographers.

Fabrication of ß-Ga2O3 Nanotubes via Sacrificial GaSb-Nanowire Templates.

ß-Ga2O3 nanostructures are attractive wide-band-gap semiconductor materials as they exhibit promising photoelectric properties and potential applications. Despite the extensive efforts on ß-Ga2O3 nanowires, investigations into ß-Ga2O3 nanotubes are rare since the tubular structures are hard to synthesize. In this paper, we report a facile method for fabricating ß-Ga2O3 nanotubes using pre-synthesized GaSb nanowires as sacrificial templates. Through a two-step heating-treatment strategy, the GaSb nanowires are partially oxidized to form ß-Ga2O3 shells, and then, the residual inner parts are removed subsequently in vacuum conditions, yielding delicate hollow ß-Ga2O3 nanotubes. The length, diameter, and thickness of the nanotubes can be customized by using different GaSb nanowires and heating parameters. In situ transmission electron microscopic heating experiments are performed to reveal the transformation dynamics of the ß-Ga2O3 nanotubes, while the Kirkendall effect and the sublimation process are found to be critical. Moreover, photoelectric tests are carried out on the obtained ß-Ga2O3 nanotubes. A photoresponsivity of ~25.9 A/W and a detectivity of ~5.6 × 1011 Jones have been achieved with a single-ß-Ga2O3-nanotube device under an excitation wavelength of 254 nm.

Primary hepatic angiosarcoma: A case report.

BACKGROUND: Primary hepatic angiosarcoma (PHA) is a rare malignant tumor of the vascular endothelium. Clinical manifestations and laboratory and imaging examinations often lack specificity for PHA. We report a case of PHA, and describe the ultrasound characteristics and characteristic changes in laboratory values associated with PHA. CASE SUMMARY: A 75-year-old woman presented with right upper quadrant abdominal pain for half a month. Magnetic resonance imaging (MRI) at a local hospital revealed multiple liver space-occupying lesions, and she was admitted to our hospital for further diagnosis. Contrast-enhanced ultrasound (CEUS) revealed multiple slightly hyperechoic nodules in the liver, which were suspected to be of malignant vascular origin. Contrast-enhanced computed tomography revealed multiple low-density nodules in the liver, considered to be metastatic hematopoietic malignancies. Contrast-enhanced MRI showed that the multiple liver nodules shared features with infectious lesions. Laboratory examination revealed normal alpha-fetoprotein levels, slightly increased other liver enzymes, decreased platelets, and significantly increased D-dimer levels. Liver biopsy and histopathology confirmed the presence of PHA. CONCLUSION: CEUS can provide valuable clues for the diagnosis of PHA and greatly improve the success rate of puncture biopsy.

Subclavian brachial plexus metastasis from breast cancer: A case report.

BACKGROUND: The common area of breast cancer metastases are bone, lung and liver. Brachial plexus metastasis from breast cancer is extremely rare. We report a case of subclavian brachial plexus metastasis from breast cancer 6 years postoperative, which were detected by ultrasound, magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT). CASE SUMMARY: Our study reports a 64-year-old woman who had right breast cancer and underwent radical mastectomy 6 years before. Ultrasound first revealed a soft lesion measuring 38 mm × 37 mm which located on the right side of the clavicle to the armpit subcutaneously. The right subclavian brachial plexus (beam level) was significantly thickened, wrapped around by a hypoechoic lesion, the surrounded axillary artery and vein were pressed. MRI brachial plexus scan showed that the right side of brachial plexus was enlarged compared with the left side and brachial plexus bundle in the distance showed a flake shadow. FDG-PET/CT revealed that the right side of brachial plexus nodular appearance with increased FDG metabolism. These results supported brachial plexus metastasis from breast cancer. Ultrasound exam also found many lesions between pectoralis major, deltoid muscle and inner upper arm. The lesion puncture was performed under ultrasound guidance and the tissue was sent for pathology. Pathology showed large areas of tumor cells in fibroblast tissue. Immunohistochemistry showed the following results: A2-1: GATA3 (+), ER (+, strong, 90%), PR (+, moderate, 10%), HER-2 (3+), Ki67 (+15%), P120 (membrane+), P63 (-), E-cadherin (+), CK5/6 (-). These results were consistent with the primary right breast cancer characteristics, thus supporting lesion metastasis from breast cancer. CONCLUSION: The brachial plexus metastasis from breast cancer is uncommon. Ultrasound has great value in detecting brachial plexus metastasis of breast cancer. It is an easy, non-invasive and affordable method. Close attention should be paid to new grown out lesions in those patients who had a history of breast cancer when doing ultrasound review.

A novel method for in situ visualization of the growth kinetics, structures and behaviours of gas-phase fabricated metallic alloy nanoparticles.

Modulation of gas-phase nanoparticles is unmethodical as there is a lack of information on the growth kinetics and its determinants. Here, we developed a novel in situ evaporation-and-deposition (EAD) method inside a transmission electron microscope which enables direct visualization of the nucleation, growth, coalescence and shape/phase evolution of gas-phase fabricated nanoparticles. Using a Bi49Pb18Sn12In21 alloy as a sample, the critical factors that determine the feasibility of this EAD method are revealed. By direct observation, it is unambiguously evidenced that pristine nanoparticles with ultra-clean surfaces are extremely energetic during growth. Coalescence between EAD-fabricated nanoparticles takes place in a manner beyond conventional understanding acquired by postmortem analyses. Moreover, the EAD-fabricated diverse nanoparticles show distinct size distributions and sandwich-type or Janus-type phase segregations. These features offer an effective tool to identify atomic surface steps of thin films and can provide an ideal case for exploring the phase diagrams of nanoalloys in the future.

Variable segment roles: modulation of the packing modes, nanocrystal morphologies and optical emissions.

Three isomers were prepared by covalently grafting carbazole (Cz) onto spiro[fluorene-9,9'-xanthene] (SFX) at different positions. Due to the complicated and variable roles of molecular segments, an evolution of the corresponding molecular packing mode was realized, accompanied by the change of nanocrystal morphology and photoluminescence properties.

Computerized-aid diagnosis of breast mass using ultrasound image.

This paper presents a comparative study of the diagnostic results of the ultrasologists with/without using a novel enhancement algorithm for breast ultrasonic images based on fuzzy entropy principle and textural information. Totally, 350 ultrasound images of 115 cases were analyzed including 59 benign and 56 malignant lesions. The original breast images were fuzzified, the edge and textural information were extracted, and the images were enhanced. The original and enhanced images were assessed and evaluated by ultrasologists using double blind method before and after enhancement. The diagnostic sensitivity and specificity were calculated by the areas (Az) under the receiver operating characteristic (ROC) curves. And the two diagnostic results before and after enhancement were compared by Chi-square test in a 2 x 2 table. The results demonstrated that the discrimination rate of breast masses had been highly improved after employing the novel enhancement algorithm. The result indicates the sensitivity could be raised from 74.3% to 89.3% with the false-positive rate 14.3%, and the area (Az) under the ROC curve of diagnosis also increased from 0.84 to 0.93. The novel enhancement algorithm can increase the classification accuracy and decrease the rate of missing and misdiagnosis, and it is useful for breast cancer control.

Study of normal Chinese vertebral-basilar arteries with transcranial color Doppler flow imaging.

OBJECTIVE: The aim of this study was to evaluate the blood flow characteristics of intracranial vertebral-basilar artery (V-BA) in healthy Chinese adults with transcranial color Doppler flow imaging (TCDFI) and provide reference values of healthy people of different ages and genders. METHODS: Three hundred healthy Chinese adults were divided into three groups based on their ages: Group I: 20-39 years, Group II: 40-59 years, Group III: >/=60 years. Each group was subdivided into two subgroups according to their gender. Peak systolic velocity (Ps), end-diastolic velocity (Vd), time average maximum velocity (TAMAX), pulsatility index (PI), and resistance index (RI) were measured from intracranial V-BA scanning. RESULTS: Ps, Vd, and TAMAX decreased with age, while PI and RI increased in all groups. Flow velocity in women was slightly higher than that of men, and there was significant differences in group III between men and women (P<.05). However, no difference was found in the flow parameters between left and right vertebral arteries. CONCLUSIONS: This study offered reference values of intracranial V-BA flow parameters in healthy Chinese adults and indicated that these parameters varied with age and gender.

Transcranial color Doppler flow imaging in detecting severe stenosis of the intracranial vertebral artery: a prospective study.

OBJECTIVE: The aims of this prospective study were to investigate the manifestations of the hemodynamics and morphology of a normal intracranial vertebral artery (VA) and diffusely severe or localized critical vertebral artery stenosis (VAS) on transcranial color Doppler flow imaging (TCDFI) and to discuss the criteria of TCDFI in detecting severe VAS. METHODS: There were 30 patients suspected of having an intracranial VAS in a patient group and 30 healthy volunteers in a control group. All the patients underwent both TCDFI and digital subtraction angiography (DSA). The intracranial VA was imaged through the suboccipital window by TCDFI. The size and tortuousness of the vessels were observed. The hemodynamics of those vessels were measured by means of peak systolic velocity (PSV) and pulsatility index (PI). RESULTS: In the control group, the VA junction with basilar artery appeared as Y shaped and filled with well-distributed blue coded on color imaging, which showed flow below the baseline with fast early systolic acceleration, and normal PSV ranged from 0.42 to 0.80 m/s on pulse wave Doppler. In the patients with diffusely severe VAS (>70% lumen reduction, the length of plaque >1 cm or multiple plaques) or localized critical VAS (>90% lumen reduction) diagnosed by TCDFI and confirmed with DSA, a narrowed and tortuous VA was demonstrated with minimal flow on color Doppler imaging and decreased 50% of normal PSV and PSV <0.30 m/s accompanied by slow early systolic acceleration on Doppler spectrum. There was a significant difference (P<.05 or P<.01) in the hemodynamic parameters (PSV and PI) between patients with severe VAS and healthy subjects. CONCLUSION: TCDFI is a useful noninvasive tool in assessing the hemodynamics of intracranial arteries. The sensitivity was 90.9% and the specificity was 75.0% by using PSV <0.30 m/s and 50% reduction of normal PSV as low cutoff criteria in the diagnosis of diffusely severe or localized critical VAS with TCDFI.

Three-dimensional transvaginal tomographic ultrasound imaging for cervical cancer staging.

The objective of this study was to investigate the feasibility of using 3-D transvaginal tomographic ultrasound imaging (TUI) to stage patients with cervical carcinoma. Eighty women with cervical cancer who underwent transvaginal TUI examinations were enrolled. In all patients, cancer was confirmed pre-operatively by pathologic examination. Staging on the basis of clinical features, ultrasonography and magnetic resonance imaging was performed according to the International Federation of Gynecology and Obstetrics (FIGO) staging system. Clinical, TUI and magnetic resonance imaging staging was compared with that based on histology. Depth of invasion into the stroma was measured by TUI in 52 cases and compared with pathologic results. An interclass correlation coefficient was used to analyze reproducibility. In total, all 80 patients underwent surgical treatment. The accuracy of pre-operative staging, compared with histologic findings, was 92.50% for TUI, 82.50% for magnetic resonance imaging and 78.75% for clinical examination. The mean depth of lesions as measured with TUI was 12.5 ± 6.2 mm (range: 3.5-40.0 mm), and that measured on histology was 10.5 ± 8.0 mm (range: 3.0-40.0 mm). The interclass correlation coefficient of the two methods was 0.933 (95% confidence interval: 0.887-0.961). Pre-operative TUI is promising as a method for pre-operative staging of cervical carcinomas. TUI can also reliably assess lesion depth.

Top-down fabrication of sub-nanometre semiconducting nanoribbons derived from molybdenum disulfide sheets.

Developments in semiconductor technology are propelling the dimensions of devices down to 10 nm, but facing great challenges in manufacture at the sub-10 nm scale. Nanotechnology can fabricate nanoribbons from two-dimensional atomic crystals, such as graphene, with widths below the 10 nm threshold, but their geometries and properties have been hard to control at this scale. Here we find that robust ultrafine molybdenum-sulfide ribbons with a uniform width of 0.35 nm can be widely formed between holes created in a MoS2 sheet under electron irradiation. In situ high-resolution transmission electron microscope characterization, combined with first-principles calculations, identifies the sub-1 nm ribbon as a Mo5S4 crystal derived from MoS2, through a spontaneous phase transition. Further first-principles investigations show that the Mo5S4 ribbon has a band gap of 0.77 eV, a Young's modulus of 300GPa and can demonstrate 9% tensile strain before fracture. The results show a novel top-down route for controllable fabrication of functional building blocks for sub-nanometre electronics.