bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relating viscoelastic nanoindentation creep and load relaxation experiments
Authors: Oyen Michelle L. 
Published: August 2008

Abstract
Nanoindentation characterization of polycarbonate is considered for load-controlled creep testing and displacement-controlled load-relaxation testing using a pyramidal Berkovich tip. An elastic – viscoelastic correspondence approach is used to obtain closed-form analytical solutions for fitting experimental data to deconvolute spring coefficients and viscosity values independently from creep and from relaxation tests. The a priori assumption of linear viscoelasticity is tested by varying the peak load and displacement levels by a factor of twenty. Results demonstrate surprisingly good agreement between parameters computed from relaxation and creep tests and little variation with load or depth. This result supports a linearly viscoelastic analysis under the conditions utilized in the current experiment, namely a Berkovich indenter tip and a glassy polymer. Plastic deformation is not explicitly considered in the current analysis, as all time-independent elastic and plastic deformation was lumped into a single effective deformation resistance term with a quadratic dependence of load on displacement. As such, obtained numerical values of the shear modulus are not representative of the material's elastic modulus. However, the technique demonstrates predictive capability across the interface between load-control and displacement-control, motivating further research on displacement-controlled nanoindentation relaxation for polymeric and biological material characterization.
Identification of viscoelastic model parameters by means of cyclic nanoindentation testing
Authors: Jäger Andreas , Lackner Roman 
Published: August 2008

Abstract
A method for the identification of model parameters describing the time-dependent material behavior by means of cyclic nanoindentation is presented. The complex shear modulus of the material sample is determined from the prescribed amplitude in the load history, the measured amplitude in the penetration history, and the phase shift between the peak values for the load and the penetration. The parameters for a specific viscoelastic model are obtained by comparing the experimentally-obtained storage and loss moduli – both depending on the frequency used during cyclic testing – with the analytical expressions for the respective viscoelastic model. The presented method is applied to low-density polyethylene, giving access to the parameters of the fractional dash-pot which is used to describe the viscoelastic behavior. The results are compared with results from nanoindentation (static) creep tests, considering different maximum loads. Finally, the performance of the presented method is assessed by comparing the creep-compliance functions corresponding to the model parameters identified by nanoindentation with the macroscopic creep-compliance function obtained from bending-beam-rheometer tests.
Effect of the indentation depth on the evaluation of mechanical properties of thin films
Authors: Calabri Lorenzo , Mantovani Sara , Rettighieri Leonardo , Valeri Sergio 
Published: August 2008

Abstract
Hardness measurement of thin films is a major topic. At the nanoscale the interplay between substrate and coating during the indentation process is not well known. Atomic force microscopy nanoindentation has been used to address this problem. We prepared a set of five chromium nitride films (100 – 500 nm thick) deposited on a steel substrate. Using nanoindentation we measured the hardness of these coatings, varying the depth of indentation and thus observing the effect of the substrate – coating interaction on the hardness evaluation. The results show that in this case (hard film on soft substrate) it is not trivial to have measurements not affected by the substrate even at very small depths of indentation. Focused ion beam cross-sections on the indentation and numerical simulations confirm these results showing a relevant contribution of the substrate to the hardness evaluation.
Mechanical properties of a-C, SiC and Ti-C: H films
Authors: Čtvrtlík Radim , Stranyánek Martin , Boháčv Petr , Kulikovsky Valeriy , Suchánek Jan 
Published: August 2008

Abstract
a-C, a-SiC and Ti-C: H coatings were deposited on two steel substrates with different hardness by magnetron sputtering. Their mechanical properties were investigated by depth sensing indentation and dry sliding testing. Load – displacement curves were obtained using a NanoTest™ NT600 instrument equipped with a Berkovich indenter. The depth profiles of the mechanical properties (indentation hardness H, effective modulus Eeff, and also H/E
eff and H
3/E
2
eff ratios) on both substrates are presented. The goal of this article is to compare the dependence of the real response of a coating/substrate system on the substrate. Regardless of substrate type the highest and the lowest values of hardness and modulus belong to a-C and Ti-C: H films, respectively.
Influence of the mathematical model on the evaluation of nanomechanical properties of ultrathin polymer layers studied by AFM
Authors: Koszewski Adam , Gorski Tomasz , Rymuza Zygmunt 
Published: August 2008

Abstract
The major research topic presented in this study concerns nanoindentation experiments of thin soft films, showing high adhesion forces. The aim of this research was to evaluate the nanomechanical properties of a 200 nm thick thermoplastic polymer layer mr-I 7000E devoted to nanoimprint lithography. The experiments were carried out using an atomic force microscopy instrument equipped with a modified 14 N m− 1 silicon cantilever tip (5 μm in diameter). The forces exerted during film indentation varied from 0 up to 2.5 μN. The Hertz and Johnson – Kendall – Roberts (JKR) models were used for analysis of the force – distance curves in order to extract the Young's modulus value. Contrary to the Hertz model, in the JKR model the adhesion force between tip and sample was considered as an additional load during the nanoindentation. The final results of these estimations were 0.20 and 0.25 GPa for the Hertz and JKR models, respectively. It shows that neglect of the adhesion force may cause an error of 20 %.
Phase equilibria in the system “MnO” – CaO – SiO2 – Al2O3 – K2O relevant to manganese smelting slags
Authors: Zhao B. , Jak E. , Hayes P. C. 
Published: August 2008

Abstract
K2O introduced with manganese ore is redistributed by evaporation and condensation within submerged arc ferromanganese smelting furnaces. To characterise the phase equilibria relevant to these slags experimental studies have been carried out to determine pseudo-ternary sections of the form “MnO” – CaO – (SiO2 + Al2O3) with a fixed Al2O3/SiO2 weight ratio of 0.65 and 6.0 wt.% K2O for temperatures in the range 1523 – 1673 K.
It was found that the presence of K2O in the slag decreases liquidus temperatures relative to those of K2O-free slags in the anorthite and gehlenite primary phase fields at low MnO concentration; at higher MnO concentration however the KAlSiO4 and KAlSi2O6 phases are formed maintaining the liquidus above 1500 K. The manganosite primary phase field is expanded in the direction of increased (Al2O3 + SiO2) and the liquidus temperatures in the manganosite primary phase field are increased significantly with the presence of K2O in the slag.
Clinical Benefit and Regulatory Outcomes of Cancer Drugs Receiving Accelerated Approval
Authors: Liu Ian T. T. , Kesselheim Aaron S. , Cliff Edward R. Scheffer 
Published: April 2024

ImportanceThe US Food and Drug Administration’s (FDA) accelerated approval pathway allows approval of investigational drugs treating unmet medical needs based on changes to surrogate measures considered “reasonably likely” to predict clinical benefit. Postapproval clinical trials are then required to confirm whether these drugs offer clinical benefit.ObjectiveTo determine whether cancer drugs granted accelerated approval ultimately demonstrate clinical benefit and to evaluate the basis of conversion to regular approval.Design, Setting, and ParticipantsIn this cohort study, publicly available FDA data were used to identify cancer drugs granted accelerated approval from 2013 to 2023.Main Outcomes and MeasuresDemonstrated improvement in quality of life or overall survival in accelerated approvals with more than 5 years of follow-up, as well as confirmatory trial end points and time to conversion for drug-indication pairs converted to regular approval.ResultsA total of 129 cancer drug–indication pairs were granted accelerated approval from 2013 to 2023. Among 46 indications with more than 5 years of follow-up (approved 2013-2017), approximately two-thirds (29, 63%) were converted to regular approval, 10 (22%) were withdrawn, and 7 (15%) remained ongoing after a median of 6.3 years. Fewer than half (20/46, 43%) demonstrated a clinical benefit in confirmatory trials. Time to withdrawal decreased from 9.9 years to 3.6 years, and time to regular approval increased from 1.6 years to 3.6 years. Among 48 drug-indication pairs converted to regular approval, 19 (40%) were converted based on overall survival, 21 (44%) on progression-free survival, 5 (10%) on response rate plus duration of response, 2 (4%) on response rate, and 1 (2%) despite a negative confirmatory trial. Comparing accelerated and regular approval indications, 18 of 48 (38%) were unchanged, while 30 of 48 (63%) had different indications (eg, earlier line of therapy).Conclusions and RelevanceMost cancer drugs granted accelerated approval did not demonstrate benefit in overall survival or quality of life within 5 years of accelerated approval. Patients should be clearly informed about the cancer drugs that use the accelerated approval pathway and do not end up showing benefits in patient-centered clinical outcomes.
Cancer Stage Compared With Mortality as End Points in Randomized Clinical Trials of Cancer Screening
Authors: Feng Xiaoshuang , Zahed Hana , Onwuka Justina , Callister Matthew E. J. , Johansson Mattias , Etzioni Ruth , Robbins Hilary A. 
Published: April 2024

ImportanceRandomized clinical trials of cancer screening typically use cancer-specific mortality as the primary end point. The incidence of stage III-IV cancer is a potential alternative end point that may accelerate completion of randomized clinical trials of cancer screening.ObjectiveTo compare cancer-specific mortality with stage III-IV cancer as end points in randomized clinical trials of cancer screening.Design, Setting, and ParticipantsThis meta-analysis included 41 randomized clinical trials of cancer screening conducted in Europe, North America, and Asia published through February 19, 2024. Data extracted included numbers of participants, cancer diagnoses, and cancer deaths in the intervention and comparison groups. For each clinical trial, the effect of screening was calculated as the percentage reduction between the intervention and comparison groups in the incidence of participants with cancer-specific mortality and stage III-IV cancer.ExposuresRandomization to a cancer screening test or to a comparison group in a clinical trial of cancer screening.Main Outcomes and MeasuresEnd points of cancer-specific mortality and incidence of stage III-IV cancer were compared using Pearson correlation coefficients with 95% CIs, linear regression, and fixed-effects meta-analysis.ResultsThe included randomized clinical trials tested benefits of screening for breast (n = 6), colorectal (n = 11), lung (n = 12), ovarian (n = 4), prostate (n = 4), and other cancers (n = 4). Correlation between reductions in cancer-specific mortality and stage III-IV cancer varied by cancer type (I2 = 65%; P = .02). Correlation was highest for trials that screened for ovarian (Pearson ρ = 0.99 [95% CI, 0.51-1.00]) and lung (Pearson ρ = 0.92 [95% CI, 0.72-0.98]) cancers, moderate for breast cancer (Pearson ρ = 0.70 [95% CI, −0.26 to 0.96]), and weak for colorectal (Pearson ρ = 0.39 [95% CI, −0.27 to 0.80]) and prostate (Pearson ρ = −0.69 [95% CI, −0.99 to 0.81]) cancers. Slopes from linear regression were estimated as 1.15 for ovarian cancer, 0.75 for lung cancer, 0.40 for colorectal cancer, 0.28 for breast cancer, and −3.58 for prostate cancer, suggesting that a given magnitude of reduction in incidence of stage III-IV cancer produced different magnitudes of change in incidence of cancer-specific mortality (P for heterogeneity = .004).Conclusions and RelevanceIn randomized clinical trials of cancer screening, incidence of late-stage cancer may be a suitable alternative end point to cancer-specific mortality for some cancer types, but is not suitable for others. These results have implications for clinical trials of multicancer screening tests.
3D Printed Elastomer‐Hydrogel Composite Meniscal Scaffolds with Biomimetic Gradient Structure and Robust Interface for Preventing Osteoarthritis and Repairing Meniscal Injuries
Authors: Yan Wenqiang , He Yangyang , Zhang Manwen , Zhao Lingyu , Tian Feng , Hu Xiaoqing , Cheng Jin , Huang Wei , Ao Yingfang , Yu Ran 
Published: April 2024

AbstractMeniscal implants with biomimetic 3D architecture, gradient mechanical properties, and excellent biocompatibility are urgently required due to the increasing incidence of meniscus injuries. Inspired by the microstructure of the meniscus, which consists of a meshwork interwoven with collagen fibers and a hydrophilic matrix filled with glycosaminoglycans and chondrocytes, here a type of structurally and functionally optimized meniscal scaffolds is prepared. Direct‐ink‐writing 3D printing technology is utilized to construct an elastomeric skeleton with a biomimetic 3D and gradient microstructure, and then hydrogel resin is infiltrated into the skeleton, resulting in an elastomer‐reinforced hydrogel composite meniscal scaffold through co‐curing of the elastomer and hydrogel resins. The composite meniscal scaffolds exhibit a highly porous structure and biomimetic gradient mechanical properties by controlling the ratio of elastomer and hydrogel materials. The co‐curing of the two materials creates robust interfaces through strong covalent bonding, ensuring their reliable long‐term mechanical performance. Furthermore, the coexistence of aqueous and oily phases of the emulsion‐type hydrogel resin allows the loading of both water‐soluble and lipid‐soluble drugs, endowing the composite scaffolds with a diphasic drug‐release capacity. The composite scaffolds are then implanted in the knee joints of beagle canines, successfully promoting the repair of meniscal injury and tissue regeneration.
Boosted Second Harmonic Generation and Cascaded Sum Frequency Generation from a Surface Crystallized Glass Ceramic Microcavity
Authors: Chen Jianhao , Huang Xiongjian , Yang Dandan , Li Yantong , Wu Jiachang , Yu Huakang , Liu Xiaofeng , Qiu Jianrong , Yang Zhongmin , Dong Guoping 
Published: April 2024

AbstractThe development of novel materials and structures for efficient second‐order nonlinear micro/nano devices remains a significant challenge. In this study, the remarkable enhancement of second‐harmonic generation (SHG) and cascaded sum frequency generation in whispering gallery mode microspheres made of surface‐crystallized glass with a 6‐µm Ba2TiSi2O8 crystal layer are demonstrated. Attributed to the core–shell design, the Ba2TiSi2O8 located on the surface can be efficiently coupled with whispering gallery modes, resulting in a highly efficient micron‐scale cavity‐enhanced second‐order optical nonlinearity. Greatly enhanced SHG of the microcavity is observed, which is up to 80 times stronger than that of a non‐resonant sample. Furthermore, owing to the wavelength non‐selectivity of random quasi‐phase matching, ultra‐wideband SHG with a strong response ranging from 860 to 1600 nm and high‐contrast polarization characteristics is demonstrated. The glass‐ceramic‐based microsphere cavity also boosts the cascading optical nonlinearity, manifested by a two‐magnitude enhancement of cascaded sum frequency generation. This work delineates an efficient strategy for boosting nonlinear optical response in glass ceramics, which will open up new opportunities for applications in photonics and optical communications.
Self‐Lubricating, Living Contact Lenses
Authors: Puertas‐Bartolomé María , Gutiérrez‐Urrutia Izabook , Teruel‐Enrico Lara Luana , Duong Cao Nguyen , Desai Krupansh , Trujillo Sara , Wittmann Christoph , del Campo Aránzazu 
Published: April 2024

AbstractThe increasing prevalence of dry eye syndrome in aging and digital societies compromises long‐term contact lens (CL) wear and forces users to regular eye drop instillation to alleviate discomfort. Here a novel approach with the potential to improve and extend the lubrication properties of CLs is presented. This is achieved by embedding lubricant‐secreting biofactories within the CL material. The self‐replenishable reservoirs autonomously produce and release hyaluronic acid (HA), a natural lubrication and wetting agent, long term. The hydrogel matrix regulates the growth of the biofactories and the HA production, and allows the diffusion of nutrients and HA for at least 3 weeks. The continuous release of HA sustainably reduces the friction coefficient of the CL surface. A self‐lubricating CL prototype is presented, where the functional biofactories are contained in a functional ring at the lens periphery, outside of the vision area. The device is cytocompatible and fulfils physicochemical requirements of commercial CLs. The fabrication process is compatible with current manufacturing processes of CLs for vision correction. It is envisioned that the durable‐by‐design approach in living CL could enable long‐term wear comfort for CL users and minimize the need for lubricating eye drops.
A Biohybrid Self‐Dispersing Miniature Machine Using Wild Oat Fruit Awns for Reforestation and Precision Agriculture
Authors: Fiorello Isabella , Ronzan Marilena , Speck Thomas , Sinibaldi Edoardo , Mazzolai Barbara 
Published: April 2024

AbstractAdvances in bioinspired and biohybrid robotics are enabling the creation of multifunctional systems able to explore complex unstructured environments. Inspired by Avena fruits, a biohybrid miniaturized autonomous machine (HybriBot) composed of a biomimetic biodegradable capsule as cargo delivery system and natural humidity‐driven sister awns as biological motors is reported. Microcomputed tomography, molding via two‐photon polymerization and casting of natural awns into biodegradable materials is employed to fabricate multiple HybriBots capable of exploring various soil and navigating soil irregularities, such as holes and cracks. These machines replicate the dispersal movements and biomechanical performances of natural fruits, achieving comparable capsule drag forces up to ≈0.38 N and awns torque up to ≈100 mN mm−1. They are functionalized with fertilizer and are successfully utilized to germinate selected diaspores. HybriBots function as self‐dispersed systems with applications in reforestation and precision agriculture.
Programmable, High‐resolution Printing of Spatially Graded Perovskites for Multispectral Photodetectors
Authors: Duan Yongqing , Yu Rui , Zhang Hanyuan , Yang Weili , Xie Wenshuo , Huang YongAn , Yin Zhouping 
Published: April 2024

AbstractMicro/nanostructured perovskites with spatially graded compositions and bandgaps are promising in filter‐free, chip‐level multispectral, and hyperspectral detection. However, achieving high‐resolution patterning of perovskites with controlled graded compositions is challenging. Here, a programmable mixed electrohydrodynamic printing (M‐ePrinting) technique is presented to realize the one‐step direct‐printing of arbitrary spatially graded perovskite micro/nanopatterns for the first time. M‐ePrinting enables in situ mixing and ejection of solutions with controlled composition/bandgap by programmatically varying driving voltage applied to a multichannel nozzle. Composition can be graded over a single dot, line or complex pattern, and the printed feature size is down to 1 µm, which is the highest printing resolution of graded patterns to the knowledge. Photodetectors based on micro/nanostructured perovskites with halide ions gradually varying from Br to I are constructed, which successfully achieve multispectral detection and full‐color imaging, with a high detectivity and responsivity of 3.27 × 1015 Jones and 69.88 A W−1, respectively. The presented method provides a versatile and competitive approach for such miniaturized bandgap‐tunable perovskite spectrometer platforms and artificial vision systems, and also opens new avenues for the digital fabrication of composition‐programmable structures.
Orbital Electrowetting‐on‐Dielectric for Droplet Manipulation on Superhydrophobic Surfaces
Authors: Tan Jie , Fan Zeng , Zhou Mingfei , Liu Tong , Sun Shulan , Chen Guijun , Song Yongchen , Wang Zuankai , Jiang Dongyue 
Published: April 2024

AbstractElectrowetting‐on‐dielectric (EWOD), recognized as the most successful electrical droplet actuation method, is essential in diverse applications, ranging from thermal management to microfluidics and water harvesting. Despite significant advances, it remains challenging to achieve repeatability, high speed, and simple circuitry in EWOD‐based droplet manipulation on superhydrophobic surfaces. Moreover, its efficient operation typically requires electrode arrays and sophisticated circuit control. Here, a newly observed droplet manipulation phenomenon on superhydrophobic surfaces with orbital EWOD (OEW) is reported. Due to the asymmetric electrowetting force generated on the orbit, flexible and versatile droplet manipulation is facilitated with OEW. It is demonstrated that OEW droplet manipulation on superhydrophobic surfaces exhibits higher speed (up to 5 times faster), enhanced functionality (antigravity), and manipulation of diverse liquids (acid, base, salt, organic, e.g., methyl blue, artificial blood) without contamination, and good durability after 1000 tests. It is envisioned that this robust droplet manipulation strategy using OEW will provide a valuable platform for various processes involving droplets, spanning from microfluidic devices to controllable chemical reactions. The previously unreported droplet manipulation phenomenon and control strategy shown here can potentially upgrade EWOD‐based microfluidics, antifogging, anti‐icing, dust removal, and beyond.
Revolutionizing Neurocare: Biomimetic Nanodelivery Via Cell Membranes
Authors: Liao Jun , Gong Lidong , Xu Qingqiang , Wang Jingya , Yang Yuanyuan , Zhang Shiming , Dong Junwei , Lin Kerui , Liang Zichao , Sun Yuhan , Mu Yongxu , Chen Zhengju , Lu Ying , Zhang Qiang , Lin Zhiqiang 
Published: April 2024

AbstractBrain disorders represent a significant challenge in medical science due to the formidable blood–brain barrier (BBB), which severely limits the penetration of conventional therapeutics, hindering effective treatment strategies. This review delves into the innovative realm of biomimetic nanodelivery systems, including stem cell‐derived nanoghosts, tumor cell membrane‐coated nanoparticles, and erythrocyte membrane‐based carriers, highlighting their potential to circumvent the BBB's restrictions. By mimicking native cell properties, these nanocarriers emerge as a promising solution for enhancing drug delivery to the brain, offering a strategic advantage in overcoming the barrier's selective permeability. The unique benefits of leveraging cell membranes from various sources is evaluated and advanced technologies for fabricating cell membrane‐encapsulated nanoparticles capable of masquerading as endogenous cells are examined. This enables the targeted delivery of a broad spectrum of therapeutic agents, ranging from small molecule drugs to proteins, thereby providing an innovative approach to neurocare. Further, the review contrasts the capabilities and limitations of these biomimetic nanocarriers with traditional delivery methods, underlining their potential to enable targeted, sustained, and minimally invasive treatment modalities. This review is concluded with a perspective on the clinical translation of these biomimetic systems, underscoring their transformative impact on the therapeutic landscape for intractable brain diseases.