The harmony of ink and printing method is of importance in producing on-demand droplets and jets of ink. Many factors including the material properties, the processing conditions, and the nozzle ...geometry affect the printing quality. In electrohydrodynamic (EHD) printing where droplets or jets are generated by the electrostatic force, the physical as well as the electrical properties of the fluid should be taken into account to achieve the desired performance. In this study, a systematic approach was suggested for finding the processing windows of the EHD printing. Six dimensionless parameters were organized and applied to the printing system of ethanol/terpineol mixtures. On the basis of the correlation of the dimensionless voltage and the charge relaxation length, the jet diameter of cone-jet mode was characterized, and the semicone angle was compared with the theoretical Taylor angle. In addition, the ratio of electric normal force and electric tangential force on the charged surface of the Taylor cone was recommended as a parameter that determines the degree of cone-jet stability. The cone-jet became more stable as this ratio got smaller. This approach was a systematic and effective way of obtaining the Taylor cone of the cone-jet mode and evaluating the jetting stability. The control of the inks with optimized experimental parameters by this method will improve the jetting performance in EHD inkjet printing.
The performance of semiconductor devices is fundamentally governed by charge-carrier dynamics within the active materials1–6. Although advances have been made towards understanding these dynamics ...under steady-state conditions, the importance of non-equilibrium phenomena and their effect on device performances remains elusive7,8. In fact, the ballistic propagation of carriers is generally considered to not contribute to the mechanism of photovoltaics (PVs) and light-emitting diodes, as scattering rapidly disrupts such processes after carrier generation via photon absorption or electric injection9. Here we characterize the spatiotemporal dynamics of carriers immediately after photon absorption in methylammonium lead iodide perovskite films using femtosecond transient absorption microscopy (fs-TAM) with a 10 fs temporal resolution and 10 nm spatial precision. We found that non-equilibrium carriers propagate ballistically over 150 nm within 20 fs of photon absorption. Our results suggest that in a typical perovskite PV device operating under standard conditions, a large fraction of carriers can reach the charge collection layers ballistically. The ballistic transport distance appears to be limited by energetic disorder within the materials, probably due to disorder-induced scattering. This provides a direct route towards optimization of the ballistic transport distance via improvements in materials and by minimizing the energetic disorder. Our observations reveal an unexplored regime of carrier transport in perovskites, which could have important consequences for device performance.Charge-carrier dynamics are fundamental to the operation and performance of semiconductor devices. In methylammonium lead iodide perovskites, carriers in the non-equilibrium regime after excitation propagate ballistically over 150 nm within 20 fs.
Mesenchymal stromal/stem cells (MSCs) have been developed as a promising source for cell‐based therapies of ischemic disease. However, there are some hurdles in their clinical application such as ...poor cell engraftment and inconsistent stem cell potency. In this study, we sought to find biomarkers for predicting potency of MSCs for proangiogenic therapy to improve their beneficial effects. Large variations were observed in proangiogenic factor secretion profiles of conditioned media derived from nine different donor‐derived Wharton's jelly (WJ)‐derived MSCs and 8 factors among 55 angiogenesis‐related factors were secreted at considerable levels. Two distinct WJ‐MSCs that had the lowest or the highest secretion of these eight factors showed corresponding proangiogenic activities in in vitro angiogenesis assays. When four additional different donor‐derived WJ‐MSCs were further examined, proangiogenic activities in migration and tube formation of endothelial cells and in in vivo Matrigel plug assay were highly consistent with secretion levels of four major factors (angiogenin, interleukin‐8, monocyte chemoattractant protein‐1, and vascular endothelial growth factor). Such correlation was also observed in vascular regenerative effect in a mouse hind limb ischemia model. Blocking of these four factors by neutralizing antibodies or knockdown of them by siRNA treatment resulted in significant inhibition of proangiogenic activities of not only WJ‐MSCs, but also bone marrow‐derived MSCs. These results suggest that these four factors may represent efficient biomarkers for predicting vascular regenerative efficacy of MSCs. Stem Cells 2019;37:77–88
Heterogeneity in the secretome profiles of mesenchymal stromal/stem cells (MSCs) derived from different donors or tissues results in inconsistent stem cell potency. A minimal set of proangiogenic factors consisting of angiogenin, IL‐8, MCP‐1, and vascular endothelial growth factor that are selected from this study is proposed as efficient biomarkers for predicting vascular regenerative efficacy in the treatment of ischemic disease. These biomarkers will be helpful for manufacturing stem cells that are reproducibly effective in the clinic.
Extracellular vesicles (EV) have been emerging as potential biomarkers for disease monitoring. In particular, tumor‐derived EV (TDE) are known to carry oncogenic miRNA, so they can be used for ...diagnosis of early cancer by analyzing the expression levels of EV‐miRNA circulating in the blood. Here, using our novel microfluidic device, we rapidly and selectively isolate cancerous EV expressing breast cancer‐derived surface markers CD49f and EpCAM within 2 minutes. Based on seven candidates of miRNA nominated from The Cancer Genome Atlas (TCGA) database, the expression levels of miRNA in TDE were validated in a total of 82 individuals, including 62 breast cancer patients and 20 healthy controls. Among seven candidates, four miRNAs (miR‐9, miR‐16, miR‐21, and miR‐429) from the EV were highly elevated in early‐stage breast cancer patients compared with healthy donors. The combination of significant miRNAs from specific EV has high sensitivities of 0.90, 0.86, 0.88, and 0.84 of the area under the receiver operating characteristic curve (AUC) in each subtype (luminal A, luminal B, HER‐2, and triple‐negative) of early‐stage breast cancer. Our results suggest that the combination of four miRNA signatures of specific EV could serve as a sensitive and specific biomarker and enable early diagnosis of breast cancer using liquid biopsy.
A new combination of miRNA from cancer‐specific extracellular vesicles was proposed for the highly sensitive and specific diagnosis of early‐stage breast cancer in association with a microfluidic‐based immuno‐isolation technique. These findings suggest that miRNA in EV could be used as important biomarkers for the early detection of breast cancer and identification of cancer subtype.
Aims
To determine the need for care robots among nurses and to suggest how robotic care should be prioritized in integrated nursing care services.
Background
Korea is expected to be a super‐aged ...society by 2030. To solve care issues with elderly inpatient caused by informal caregivers, the government introduced “integrated nursing care services”; these are comprehensive care systems staffed by professionally trained nurses. To assist them, a care robot development project has been launched.
Design
The study applied a cross‐sectional survey.
Methods
In 2016, we conducted a multicentre survey involving 302 Registered Nurses in five hospitals including three tertiary and two secondary hospitals in Korea. The questionnaire consisted of general characteristics of nurses and their views on and extents of agreement about issues associated with robotic care.
Results
Trial centre nurses and those with ≥10 years of experience reported positively on the prospects for robotic care. The top‐three desired primary roles for care robots were “measuring/monitoring”, “mobility/activity” and “safety care”. “Reduction in workload”, especially in terms of “other nursing services” which were categorized as nonvalue‐added nursing activities, was the most valued feature. The nurses approved of the aid by care robots but were concerned about device malfunction and interruption of rapport with patients.
Conclusion
Care robots are expected to be effective in integrated nursing care services, particularly in “measuring/monitoring”. Such robots should decrease nurses’ workload and minimize nonvalue‐added nursing activities efficiently. No matter how excellent care robots are, they must cooperate with and be controlled by nurses.
Human exposure to flame retardants (FRs) in indoor environments is a growing concern. In this study, the concentrations of polybrominated diphenyl ethers (PBDEs) and their alternatives, such as novel ...brominated flame retardants (NBFRs), dechlorane plus (DP), and organophosphate flame retardants (OPFRs), were measured in dust from indoor environments in Korea to investigate their occurrence, contamination profiles, and health risks. Legacy and emerging FRs were detected in dust samples, indicating widespread contamination of indoor environments. The concentrations of alternative FRs were higher in dust from offices compared with house dust, suggesting that office environments are major consumers of alternative FRs. Similar compositional profiles for indoor dust were found for PBDEs in different microenvironments and regions, while OPFR composition varied widely due to disparate applications. The estimated daily intakes of PBDEs, NBFRs, and OPFRs via dust ingestion were lower than the reference doses proposed by previous studies. A multiple-exposure assessment showed that dust ingestion was a major contributor to total PBDEs for toddlers and adults. However, major exposure pathways of BDEs 47 and 209 differed between toddlers and adults. Our study suggests that multiple exposure pathways should be considered in a comprehensive exposure assessment of PBDEs.
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•PBDEs and their alternatives were ubiquitously contaminated in different microenvironments.•Concentrations of alternative flame retardants were higher in offices than in houses.•Compositions of OPFRs in indoor dust varied depending on microenvironment.•Dust ingestion was a major contributor to PBDE exposure through multiple pathways.•Major exposure pathways of BDEs 47 and 209 were different for toddlers and adults.
Three-dimensional (3D) cell printing systems allow the controlled and precise deposition of multiple cells in 3D constructs. Hydrogel materials have been used extensively as printable bioinks owing ...to their ability to safely encapsulate living cells. However, hydrogel-based bioinks have drawbacks for cell printing, e.g. inappropriate crosslinking and liquid-like rheological properties, which hinder precise 3D shaping. Therefore, in this study, we investigated the influence of various factors (e.g. bioink concentration, viscosity, and extent of crosslinking) on cell printing and established a new 3D cell printing system equipped with heating modules for the precise stacking of decellularized extracellular matrix (dECM)-based 3D cell-laden constructs. Because the pH-adjusted bioink isolated from native tissue is safely gelled at 37 °C, our heating system facilitated the precise stacking of dECM bioinks by enabling simultaneous gelation during printing. We observed greater printability compared with that of a non-heating system. These results were confirmed by mechanical testing and 3D construct stacking analyses. We also confirmed that our heating system did not elicit negative effects, such as cell death, in the printed cells. Conclusively, these results hold promise for the application of 3D bioprinting to tissue engineering and drug development.
Environmental contamination by organophosphate flame retardants (OPFRs) and plasticizers are environmental concerns. In this study, 18 OPFRs were analyzed in sediment and bivalves collected from 50 ...locations along the Korean coast to assess occurrence, geographical distribution, contamination source, and bioaccumulation potential. Tris(1-chloro-2-propanyl) phosphate (TCPP) and tris(2-ethylhexyl) phosphate (TEHP) were highly detected (>80%) OPFRs in sediment and bivalves. Total concentrations of OPFRs and plasticizers in sediment and bivalves ranged from 2.18 to 347 ng/g dry weight and from 6.12 to 206 ng/g dry weight, respectively, which were within the ranges reported for previous studies. Sedimentary organic carbon was a primary factor governing the OPFR distribution. Concentrations of OPFRs and plasticizers in sediments from harbor zones were significantly higher than non-harbor zones, indicating that shipping activity is a contamination source of OPFRs and plasticizers in coastal environments. Biota-sediment accumulation factors <1 for several OPFRs indicated limited potential for bioaccumulation.
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•OPFRs and plasticizers were detected in all sediment and bivalves along the Korean coast.•TCPP was a major OPFR and plasticizer compound in sediment and bivalves.•Shipping activity is a significant OPFR contamination source in coastal environments.•Biota-sediment accumulation factors of OPFRs indicate a limited bioaccumulation potential.
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