Angelica sinensis polysaccharides alleviate the oxidative burden on hematopoietic cells by restoring 5-fluorouracil-induced oxidative damage in perivascular mesenchymal progenitor cells

CONTEXT

5-Fluorouracil (5-FU)-injured stromal cells may cause chronic bone marrow suppression; however, the underlying mechanism remains unclear. Angelica sinensis polysaccharide (ASP), the main biologically active ingredient of the Chinese herb, Angelica sinensis (Oliv.) Diels (Apiaceae), may enrich the blood and promote antioxidation.

OBJECTIVE

This study investigated the protective antioxidative effects of ASP on perivascular mesenchymal progenitors (PMPs) and their interactions with hematopoietic cells.

MATERIALS AND METHODS

PMPs were dissociated from C57BL/6 mouse femur and tibia and were subsequently divided into the control, ASP (0.1 g/L), 5-FU (0.025 g/L), and 5-FU + ASP (pre-treatment with 0.1 g/L ASP for 6 h, together with 0.025 g/L 5-FU) then cultured for 48 h. Hematopoietic cells were co-cultured on these feeder layers for 24 h. Cell proliferation, senescence, apoptosis, and oxidative indices were detected, along with stromal osteogenic and adipogenic differentiation potentials. Intercellular and intracellular signaling was analyzed by real-time quantitative reverse transcription polymerase chain reaction and Western blotting.

RESULTS

ASP ameliorated the reactive oxygen species production/scavenge balance in PMPs; improved osteogenic differentiation; increased SCF, CXCL12, VLA-4/VCAM-1, ICAM-1/LFA1, and TPO/MPL, Ang-1/Tie-2 gene expression. Further, the ASP-treated feeder layer alleviated hematopoietic cells senescence (from 21.9 ± 1.47 to 12.1 ± 1.13); decreased P53, P21, p-GSK-3β, β-catenin and cyclin-D1 protein expression, and increased glycogen synthase kinase (GSK)-3β protein expression in co-cultured hematopoietic cells.

DISCUSSION AND CONCLUSIONS

ASP delayed oxidative stress-induced premature senescence of 5-FU-treated feeder co-cultured hematopoietic cells via down-regulation of overactivated Wnt/β-catenin signaling. These findings provide a new strategy for alleviating myelosuppressive stress.

Rg1 alleviates oxidative stress and spermatogonium apoptosis in D-gal-induced testicular toxicity by activating Akt

ABSTRACTObjectives: High reactive oxygen species (ROS) levels lead to cell death, and the testes are among the most vulnerable organs to oxidative damage. Rg1, an active ingredient extracted from the natural medicine ginseng, has potential anti-inflammatory, antioxidant and antiapoptotic properties. Our previous studies showed that Rg1 can effectively improve spermatogenic function in mice, but the specific mechanism remains unclear. The purpose of this study was to investigate the effect of Rg1 on oxidative stress and spermatogonium apoptosis in D-gal-induced testicular toxicity and elucidate the associated mechanism.Methods: Male C57BL/6 mice at 6-8 weeks of age were intraperitoneally injected with D-gal (200 mg/kg) for 42 days to establish a testicular injury model, and on day 16, 40 mg/kg Rg1-rich saline was injected intraperitoneally. Concurrently, we established an in vitro model of D-gal-damaged spermatogonia, which was treated with Rg1.Results: We found that treatment with the ginsenoside Rg1 reduced D-gal-induced oxidative stress and spermatogonium apoptosis in vivo and in vitro. Mechanistically, we found that Rg1 activated Akt/bad signaling and reduced D-gal-induced spermatogonium apoptosis.Discussion: We provide evidence showing that the antioxidant effect of Rg1 is mediated by the Akt/GSK-3β/NRF2 axis. Based on these findings, we consider Rg1 a potential treatment for testicular oxidative damage.

The effect of previous orbital decompression on outcomes of rectus muscle recession surgery in patients with thyroid ophthalmopathy

PURPOSE

To evaluate the effect of previous orbital decompression on outcomes of rectus muscle recession surgery in patients with thyroid-associated ophthalmopathy.

METHODS

This retrospective study enrolled 55 eyes of 33 patients treated in our hospital for restrictive strabismus caused by thyroid-associated ophthalmopathy. We performed muscle recession for the obviously restricted extraocular muscles, with 6 weeks of follow-up. Surgical outcomes were compared between the orbital decompression group (DG, n=15) and non-orbital decompression group (NDG, n=18).

RESULTS

A total of 33 patients with Graves' ophthalmopathy who underwent rectus muscle recession surgery were included. Of these, 15 patients had undergone orbital decompression prior to strabismus surgery, and 18 had not. The two groups did not differ in terms of the preoperative horizontal or vertical ocular deviation, degree of restriction of eye movement, degree of diplopia, or mean number of muscles that underwent surgery (P>0.05). There was no significant difference in the preoperative horizontal or vertical ocular deviation, level of eye movement restriction, degree of diplopia and the success rate of the surgery (P>0.05).

CONCLUSION

Rectus muscle recession surgery in patients with thyroid-associated ophthalmopathy during the quiescent period could improve the ocular deviation and diplopia, and orbital decompression performed before strabismus surgery had no significant effect on surgical technique or outcomes of rectus muscle recession surgery.

Ginsenoside Rg1 attenuates D-galactose-induced neural stem cell senescence via the Sirt1-Nrf2-BDNF pathway

With the ageing of society's population, neurodegenerative diseases have become an important factor affecting the quality of life and mortality in the elderly. Since its physiopathological processes are complex and the authorized medications have recently been shown to have several adverse effects, the development of safe and efficient medications is urgently needed. In this study, we looked at how ginsenoside Rg1 works to postpone neural stem cell ageing and brain ageing, giving it a solid scientific foundation for use as a therapeutic therapy for neurodegenerative diseases.

Anaemia prevalence and risk factors among children aged 6 to 23 months in rural China

INTRODUCTION

Anaemia is a global public health problem among children. However, few studies have examined anaemia prevalence and risk factors among Chinese children of different ages, particularly in poor rural areas. This study investigated these two aspects among children aged 6 to 23 months in poor rural areas of China.

METHODS

This cross-sectional study included 1132 children aged 6 to 23 months in three prefectures of the Qinba Mountains area. A finger prick blood test for haemoglobin and anaemia was conducted, along with household surveys of socio-demographic characteristics, illness characteristics, and feeding practices. Multiple linear and logistic regression analyses were used to determine predictors of anaemia.

RESULTS

Overall, 42.6% of children in the study displayed anaemia. Children aged 6 to 11 months had the highest anaemia prevalence (53.6%). Anaemia risk factors differed among age-groups and throughout the overall sample. Bivariate and multivariable regression results showed that continued breastfeeding, any history of formula feeding, and consumption of iron-rich or iron-fortified foods were prominent risk factors for anaemia. However, continued breastfeeding and any history of formula feeding had the greatest impact across age-groups (both P<0.05).

CONCLUSION

Anaemia remains a severe public health problem among children aged 6 to 23 months in rural China. Healthy feeding practices, nutritional health knowledge, and nutrition improvement projects are needed to reduce the burden of anaemia among children in rural areas of China.

Angelica Sinensis polysaccharide antagonizes 5-Fluorouracil-induced spleen injury and dysfunction by suppressing oxidative stress and apoptosis

Angelica Sinensis polysaccharide (ASP), the main active component of Angelica sinensis, possesses antioxidative and anti-apoptotic properties. In this study, we have investigated the antagonistic effect of ASP on 5-FU-induced injury of mouse spleen in vivo and splenocytes in vitro, and its possible mechanism. Our results showed that ASP inhibited 5-FU-induced decreases in spleen weight and organ index in mice, restored the number of peripheral blood leukocytes and lymphocytes, repaired spleen structure disorder and functional impairment, rescued serum IL-2, IL-6, and IFN-γ levels, and relieved 5-FU-induced mitochondrial swelling， reduced the oxidant accumulation including MDA and ROS, whereas increasing the activities of GSH, SOD and CAT. The mechanism may be related to ASP downregulation of Keap1 protein expression thus motivating the nuclear translocation of Nrf2. Furthermore, ASP alleviated the apoptosis of spleens in vivo and splenocytes in vitro, and reactivated PI3K / AKT signalling. In conclusion, the protective effect of ASP on spleens and splenocytes may be related to the reduction of oxidative stress and apoptosis via reactivation of Nrf2 and PI3K/AKT pathways. This study has provided a new protective agent for minimizing the spleen injury caused by 5-FU and a new idea for improving the prognosis of chemotherapy patients.

Asthenopia prevalence and vision impairment severity among students attending online classes in low-income areas of western China during the COVID-19 pandemic

INTRODUCTION

This study explored the impact of online learning during the coronavirus disease 2019 (COVID-19) pandemic on asthenopia and vision impairment in students, with the aim of establishing a theoretical basis for preventive approaches to vision health.

METHODS

This balanced panel study enrolled students from western rural China. Participant information was collected before and during the COVID-19 pandemic via questionnaires administered at local vision care centres, along with clinical assessments of visual acuity. Paired t tests and fixed-effects models were used to analyse pandemic-related differences in visual status.

RESULTS

In total, 128 students were included (mean age before pandemic, 11.82 ± 1.46 years). The mean total screen time was 3.22 ± 2.90 hours per day during the pandemic, whereas it was 1.97 ± 1.90 hours per day in the pre-pandemic period (P<0.001). Asthenopia prevalence was 55% (71/128) during the pandemic, and the mean visual acuity was 0.81 ± 0.30 logarithm of the minimum angle of resolution; these findings indicated increasing vision impairment, compared with the pre-pandemic period (both P<0.001). Notably, asthenopia prevalence increased by two- to three-fold, compared with the pre-pandemic period. An increase in screen time while learning was associated with an increase in asthenopia prevalence (P=0.034).

CONCLUSION

During the COVID-19 pandemic, students spent more time on online classes, leading to worse visual acuity and vision health. Students in this study reported a significant increase in screen time, which was associated with increasing asthenopia prevalence and worse vision impairment. Further research is needed regarding the link between online classes and vision problems.

Teacher-to-parent communication and vision care-seeking behaviour among primary school students

INTRODUCTION

To determine the associations between teacher-to-parent communication and vision care-seeking behaviour among students.

METHODS

This cross-sectional study included 19 934 students from 252 primary schools in two prefectures in western China. Information regarding the sampled students was collected through questionnaires and vision examinations. Eligible students with uncorrected refractive error were allocated to four groups according to whether and how parents were informed about vision problems in their children: uninformed, informed by only teachers or only students, or informed by both. The relationship between teacher-to-parent communication and vision care-seeking behaviour was analysed by multiple logistic regression.

RESULTS

Among valid responses (n=2922) analysed, 42.3% (n=1235) of parents were not informed about vision problems in their children. Teacher-to-parent communication enabled 35.9% (n=1050) of parents to learn about vision problems in their children. When only teachers informed parents, the odds of students having refraction examinations (odds ratio [OR]=1.499; P=0.002) and spectacles ownership (OR=1.755; P=0.002) were significantly higher than for students in the uninformed group. When both students and teachers informed parents, the odds of students having refraction examinations (OR=5.565; P<0.001) and spectacles ownership (OR=7.935; P<0.001) were highest.

CONCLUSIONS

Knowledge of vision problems is an essential step in vision care for students. Teacherto- parent communication concerning vision problems is positively associated with the rate of vision care-seeking behaviour. Teacher-to-parent communication provides an important route for parents to learn about vision problems in their children.

Sentinel lymph node biopsy with carbon nanoparticle suspension after neoadjuvant chemotherapy for breast cancer patients

INTRODUCTION

The aim of the study was to explore the feasibility of performing sentinel lymph node biopsy (SLNB) using a carbon nanoparticle suspension (CNPS) after neoadjuvant chemotherapy in breast cancer patients.

METHODS

Some 152 patients diagnosed with primary breast cancer (cT1-3N0-2M0) were recruited. Patients were divided into two groups according to axillary lymph node (ALN) status after four to six cycles of neoadjuvant chemotherapy. All patients received a CNPS injection, after which SLNB and axillary lymph node dissection (ALND) were performed.

RESULTS

Sentinel lymph nodes (SLN) of 143 patients were identified; with an accuracy rate of 94.4% and a false-negative rate of 9.9%. Group A included 67 patients, and the detection, accuracy and false-negative rates within this group were 95.5%, 96.9% and 6.7%, respectively. The corresponding rates for group B (85 patients) were 92.9%, 92.4% and 11.8%, respectively.

CONCLUSIONS

CNPS is an ideal tracer for improving the detection rate of SLN and can be used to determine SLN status following neoadjuvant chemotherapy.

[Analysis of families with fetal congenital abnormalities but negative prenatal diagnosis by whole exome sequencing]

Objective: To evaluate the value of whole exome sequencing (WES) in prenatal clinical application. Methods: A total of 1 152 cases of congenital abnormal [including structural malformation, nuchal translucency (NT) thickening and intrauterine growth restriction] with traditional prenatal diagnosis [including G-band karyotype analysis and chromosome microarray analysis (CMA)] negative were analyzed. The congenital abnormal fetuses were divided into retrospective group and prospective group according to the time of WES detection, that is whether the pregnancy termination or not. According to the specific location of fetal malformation and their family history, the cohort was divided into subgroups. The clinical prognosis of all fetuses were followed up, and the effect of WES test results on pregnancy decision-making and clinical intervention were analyzed. According to the follow-up results, the data of fetuses with new phenotypes in the third trimester or after birth were re-analyzed. Results: Among 1 152 families who received WES, 5 families were excluded because of nonbiological parents. Among the remaining 1 147 families, 152 fetuses obtained positive diagnosis (13.3%,152/1 147), including 74 fetuses in the retrospective group (16.1%,74/460) and 78 fetuses in the prospective group (11.4%,78/687). In fetuses with negative CMA and G-band karyotype analysis results but new phenotypes in the third trimester or after birth, the positive rate by WES data re-analysis was 4.9% (8/163). A total of 34 (21.3%, 34/160) fetuses were directly affected by the corresponding positive molecular diagnosis. Among 68 cases of live births with diagnostic variation grade 4, 29 cases (42.7%, 29/68) received appropriate medical intervention through rapid review of WES results. Conclusions: WES could increase the detection rate of abnormal fetuses with negative G-banding karyotype analysis and CMA by 13.3%. Prenatal WES could guide pregnancy decision-making and early clinical intervention. It might be an effective strategy to pay attention to the special follow-up of the third trimester and postnatal fetus and to re-analyze the WES data.

microRNA-29b mediates Th17/Treg imbalance in chronic obstructive pulmonary disease by targeting IL-22

Chronic obstructive pulmonary disease (COPD) represents a chronic inflammatory disorder of the airways induced mainly by cigarette smoking. In the current study, cigarette smoke extract (CSE) was used to develop an in vitro COPD model using human bronchial epithelium (HBE) cells to expound the possible role of microRNA-29b (miR-29b) in COPD. Firstly, miR-29b and interleukin (IL)-22 expression was assessed in serum of 20 healthy non-smokers, 20 healthy smokers and 20 COPD patients as well as CSE-treated HBE cells. Then, miR-29b and IL-22 expression was altered to evaluate their functions in Th17/Treg ratio. miR-29b inhibited Th17/Treg ratio and levels of IL-22; whereas overexpression of IL-22 reversed these trends. Moreover, rescue experiments found that IL-22 neutralized the repressive effects of miR-29b on Th17/Treg ratio and inflammatory response. Finally, we found that miR-29b blocked the JAK/STAT3 pathway in CSE-treated HBE cells. These data highlighted that miR-29bs modulated Th17/Treg imbalance in CSE-induced experimental COPD through inhibition of IL-22-dependent JAK/STAT3 pathway.

Visual impairment and spectacles ownership among upper secondary school students in northwestern China

PURPOSE

To assess the prevalence of visual impairment and spectacles ownership among academic and vocational upper secondary school students in rural China.

METHODS

This cross-sectional study included 5583 students from four academic upper secondary schools (AUSSs) and two vocational upper secondary schools (VUSSs) in Mei and Qianyang counties, Baoji Prefecture, Shaanxi Province. In March and April 2016, students underwent assessment of visual acuity (VA) and completed a questionnaire regarding spectacles use and family characteristics. Students with visual impairment (presenting VA ≤6/12 in the better eye) and students needing spectacles (uncorrected VA ≤6/12 in the better eye, which could be improved to >6/12 with refraction) were identified.

RESULTS

Among 5583 students (54% boys, mean age 16.4±1.0 years) in grades 10 and grade 11 attending AUSSs (n=4549) and VUSSs (n=1034), visual impairment was detected in 4026 students. Among the AUSS students, 3425 (75%) needed spectacles; 2551 (75%) had them. Among the VUSS students, 601 (58%) needed spectacles; this proportion was significantly smaller (P=0.004), as was the proportion who had spectacles (n=212, 35%, P<0.001), compared with the AUSS students. Multivariate analysis showed that ownership of spectacles among children who needed them was associated with worse uncorrected VA (P<0.001), male sex (P<0.001), and residence in an urban area (P<0.034). Spectacles ownership was also strongly associated with AUSS education (P<0.001).

CONCLUSION

There is a high rate of unmet need in visual care among upper secondary school students. Lack of spectacles ownership among children who needed them was significantly associated with VUSS education.

Manipulating topological transformations of polar structures through real-time observation of the dynamic polarization evolution

Topological structures based on controllable ferroelectric or ferromagnetic domain configurations offer the opportunity to develop microelectronic devices such as high-density memories. Despite the increasing experimental and theoretical insights into various domain structures (such as polar spirals, polar wave, polar vortex) over the past decade, manipulating the topological transformations of polar structures and comprehensively understanding its underlying mechanism remains lacking. By conducting an in-situ non-contact bias technique, here we systematically investigate the real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers at an atomic level. The procedure of vortex pair splitting and the transformation from polar vortex to polar wave and out-of-plane polarization are observed step by step. Furthermore, the redistribution of charge in various topological structures has been demonstrated under an external bias. This provides new insights for the symbiosis of polar and charge and offers an opportunity for a new generation of microelectronic devices.

Direct observation of the dynamic evolution of polar domain structures at atomic level remains challenging. Here, the authors report the observation of real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers.

Economic Impact of Hospitalizations in US Adults with Sarcopenia

BACKGROUND

Sarcopenia is characterized by progressive loss of muscle mass with corresponding decline in strength and/or physical function. The economic burden of sarcopenia-associated disability is considerable in the US.

OBJECTIVE

To estimate the cost of hospitalizations in US adults with sarcopenia categorized by age, sex, and race/ethnicity.

DESIGN, SETTING AND PARTICIPANTS

A retrospective, prevalence based, economic burden study, consisting of 4011 adults aged ≥40 years with and without sarcopenia.

METHODS

Data on prevalence of low lean mass, functional limitations, and hospitalizations were obtained from the National Health and Nutrition Examination Survey (1999-2004); cost of hospitalizations was obtained from the Healthcare Cost and Utilization Project - National Inpatient Sample (2014), and population estimates were obtained from the US Census (2014). Probability and cost of hospitalizations were estimated by multiple logistic regression and negative binomial regression models, respectively.

RESULTS

The total estimated cost of hospitalizations in individuals with sarcopenia was USD $40.4 billion with an average per person cost of USD $260. Within this category, average per person cost was highest for Hispanic women (USD $548) and lowest for Non-Hispanic Black women (USD $25); average per person cost was higher for older adults (≥65 years) (USD $375) than younger adults (40-64 years) (USD $204) with sarcopenia. The total cost of hospitalizations in individuals with sarcopenia (≥65 years) was USD $19.12 billion. Individuals with sarcopenia had greater odds of hospitalization (OR, 1.95; p<.001) compared to those without and had an annual marginal increase in cost of USD $2315.7 per person compared to individuals without sarcopenia.

CONCLUSION

Sarcopenia places considerable economic burden on the US healthcare system. The ethnic disparity and economic burden associated with sarcopenia warrant further investigation.

The Griffiths Development Scales-Chinese (GDS-C): A cross-cultural comparison of developmental trajectories between Chinese and British children

BACKGROUND

The Griffiths Mental Development Scales (GMDS) are used in many countries to assess the development of children from birth to 8 years. There is a need for accurate and culturally appropriate developmental assessment tools for Chinese children. Here, we adapted the GMDS for use in Chinese children and compare the developmental trajectories between Chinese and British children.

METHODS

Children with typical development were recruited from 7 urban cities in China between 2009 and 2013. The Griffiths Mental Development Scales-Chinese (GDS-C) were adapted and used to assess the development of urban Chinese children. Developmental curves were computed for 6 subscales using learning management system methods and compare against the British curves from the Griffiths Mental Development Scales-Extended Revised (GMDS-ER).

RESULTS

The GDS-C were used to assess the developmental status of 815 Chinese children. Plots of the 1st, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 99th percentiles, and full percentile tables were obtained, which showed similar trends to data from the British GMDS-ER.

CONCLUSIONS

The Chinese developmental curves obtained from the GDS-C showed similarities and differences to the developmental curves from the British GMDS-ER. The development of urban Chinese children should be assessed with the culturally appropriate GDS-C.

Recyclable heat-resisting polymer poly(ether azaindole ketone)-H+via hydrogen bonding crosslinking

A novel recyclable hydrogen bonding crosslinked polymer PEAINKH⁺ was prepared, which possesses outstanding thermal stability.

Simultaneous detection of 45 fusion genes in leukemia by dual-color fluorescence real-time PCR

INTRODUCTION

Detection of recurrent genetic abnormalities is of great significance for a refined diagnosis and assessment of prognosis in leukemia. Conventional nested reverse transcription PCR is labor intensive and time-consuming.

METHODS

We have developed a novel dual-color TaqMan probe-based real-time PCR method for the simultaneous screening of 45 fusion transcripts in 12 parallel reactions. The method was tested and validated with cell lines carrying known fusion transcripts and patient samples.

RESULTS

A multiplex real-time PCR method was successfully developed for rapid detection of 45 fusion genes and validated for 15 of the more commonly detected fusion genes. Intra-assay reproducibility assessed for the most frequent rearrangements ranged from 0.41% to 0.74% for the coefficient of variation (CV) of cycle threshold (Ct) and the interassay reproducibility ranged from 1.62% to 2.83% in five separate experiments. The lowest detection limit for the translocations tested ranged between 1 : 16 000 and 1 : 32 000. Validation of the method with 213 patient samples showed 100% specificity and excellent consistence with conventional nested RT-PCR.

CONCLUSION

Overall, we believe that this method is easily applicable, cost-effective, and clinically useful for a rapid screening of fusion genes in the initial diagnostic phase of leukemia. Its use can also be extended to the monitoring of minimal residual disease.

Multiplexed efficient on-chip sample preparation and sensitive amplification-free detection of Ebola virus

An automated microfluidic sample preparation multiplexer (SPM) has been developed and evaluated for Ebola virus detection. Metered air bubbles controlled by microvalves are used to improve bead-solution mixing thereby enhancing the hybridization of the target Ebola virus RNA with capture probes bound to the beads. The method uses thermally stable 4-formyl benzamide functionalized (4FB) magnetic beads rather than streptavidin coated beads with a high density of capture probes to improve the target capture efficiency. Exploiting an on-chip concentration protocol in the SPM and the single molecule detection capability of the antiresonant reflecting optical waveguide (ARROW) biosensor chip, a detection limit of 0.021pfu/mL for clinical samples is achieved without target amplification. This RNA target capture efficiency is two orders of magnitude higher than previous results using streptavidin beads and the limit of detection (LOD) improves 10×. The wide dynamic range of this technique covers the whole clinically applicable concentration range. In addition, the current sample preparation time is ~1h which is eight times faster than previous work. This multiplexed, miniaturized sample preparation microdevice establishes a key technology that intended to develop next generation point-of-care (POC) detection system.

Transition of dislocation nucleation induced by local stress concentration in nanotwinned copper

Metals with a high density of nanometre-scale twins have demonstrated simultaneous high strength and good ductility, attributed to the interaction between lattice dislocations and twin boundaries. Maximum strength was observed at a critical twin lamella spacing (∼15 nm) by mechanical testing; hence, an explanation of how twin lamella spacing influences dislocation behaviours is desired. Here, we report a transition of dislocation nucleation from steps on the twin boundaries to twin boundary/grain boundary junctions at a critical twin lamella spacing (12–37 nm), observed with in situ transmission electron microscopy. The local stress concentrations vary significantly with twin lamella spacing, thus resulting in a critical twin lamella spacing (∼18 nm) for the transition of dislocation nucleation. This agrees quantitatively with the mechanical test. These results demonstrate that by quantitatively analysing local stress concentrations, a direct relationship can be resolved between the microscopic dislocation activities and macroscopic mechanical properties of nanotwinned metals.

Metallic materials with a nanometre-scaled lamella structure can have properties that are very different from their coarser-grained counterparts. Here, the authors demonstrate how dislocations in such a material—nanotwinned copper—can nucleate in two distinctly different mechanisms depending on local stress