RESUMO
Passive radiative cooling technology is an eco-friendly and energy-free alternative to conventional cooling systems. However, a major challenge in implementing radiative cooling in an outdoor environment is the presence of contamination, which significantly degrades the cooling effectiveness. In response to this challenge, researchers have explored superhydrophobic radiative coolers with self-cleaning abilities as a potential solution. In this Perspective, we summarize the latest progress and highlight certain design principles and strategies for integrating superhydrophobicity into radiative cooling structures. These strategies can be classified into three distinct categories: spraying particles, constructing pores, and creating patterns. Finally, we identify future challenges and opportunities in superhydrophobic radiative coolers, intending to push the technology toward practical applications.
RESUMO
Biological fluorescence imaging technologies have attracted a lot of attention and have been widely used in biomedical fields. Compared with other technologies, fluorescence imaging has a lower cost, higher sensitivity, and easier operation. However, due to the disadvantages of one-photon (OP) fluorescence imaging, such as low spatial and poor temporal resolution and poor tissue permeability depth, the application of OP fluorescence imaging has some limitations. Though two-photon (TP) fluorescence imaging can well overcome these shortcomings of OP, the single-mode imaging remains deficient. Therefore, dual-mode imaging combined with TP imaging and magnetic resonance imaging (MRI) can make up for the deficiency well, which make dual-mode imaging for the early diagnosis of diseases more accurate. Hence, a dual-mode nanoprobe TP-CQDs@MnO2 was designed for probing the fluorescence/MR dual-mode imaging strategy of intracellular H+ by using TP-CQDs (two photon-carbon quantum dots) and MnO2 nanosheets. The MnO2 nanosheets treated as fluorescence quenching agents of TP-CQDs exhibited a supersensitive response to H+, which made the fluorescence signals turn "off" to "on" for TP fluorescence imaging, in the meantime, large amounts of Mn2+ were generated for MRI. A dual-mode nanoprobe TP-CQDs@MnO2 can monitor intracellular wide pH (4.0-8.0), and the fluorescence intensity of TP-CQDs@MnO2 has recovered up to more than six times and the corresponding results of MRI were satisfactory. TP fluorescence imaging of cells and tissues showed higher detection sensitivity and deeper tissue penetration (240.0 µm) than OP. The dual-mode imaging platform hold great promise for pH-related early diagnosis and treatment, which has great potential to improve clinical efficacy.
Assuntos
Compostos de Manganês , Pontos Quânticos , Concentração de Íons de Hidrogênio , Imageamento por Ressonância Magnética , Imagem Óptica , ÓxidosRESUMO
Two-photon fluorescence imaging is one of the most attractive imaging techniques for monitoring important biomolecules in the biomedical field due to its advantages of low light scattering, high penetration depth, and suppressed photodamage/phototoxicity under near-infrared excitation. However, in actual biological imaging, organic two-photon fluorescent dyes have disadvantages such as high biological toxicity and their fluorescence efficiency is easily affected by the complex environment in organisms. In this study, a novel nanoprobe platform with two-photon dye-doped silica nanoparticles was developed for FRET-based ratiometric biosensing and bioimaging, with endogenous ATP chosen as the target for detection. The nanoprobe has three components: (1) a two-photon dye-doped silica nanoparticle core, which serves as an energy donor for FRET; (2) amino-modified hairpin primers with carboxy fluorescein as an energy acceptor for FRET; (3) an aptamer acting as a recognition unit to realize the probing function. The nanoprobe showed ratiometric fluorescence responses for ATP detection with high sensitivity and high selectivity in vivo. Moreover, the nanoprobe showed satisfactory ratiometric two-photon fluorescence imaging of endogenous ATP in living cells and tissues (penetration depth of 190 nm). These results indicated that novel two-photon silica nanoparticles can be constructed by doping a two-photon fluorescent dye into silica nanoparticles, and they can effectively solve the disadvantages of two-photon fluorescent dyes. These excellent performances indicate that this novel nanoprobe platform will become a very valuable molecular imaging tool, which can be widely used in the biomedical field for drug screening and disease diagnosis and other related research.
Assuntos
Nanopartículas , Dióxido de Silício , Trifosfato de Adenosina , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/toxicidade , Nanopartículas/toxicidade , Fótons , Dióxido de Silício/toxicidadeRESUMO
The mechanical behavior of vertically aligned carbon nanotube (VACNT) arrays can largely impact their adhesion performance. In this paper, we fabricated various VACNT arrays to investigate the relationship between adhesion force and their mechanical behavior. High-volume fraction (3.4%) CNT arrays did not exhibit the applicable adhesion effect due to their intrinsic elastic property. Adhesion measurements on several low-density (less than 0.5%) VACNT arrays demonstrated that the adhesion performance is strongly related to the plastic deformation of the carbon nanotubes at the contact surface. Due to the nature of the growth of CNT arrays, the top region of the as-grown CNT arrays is denser and stiffer than the bottom region of the arrays. Therefore, compared with as-grown CNT arrays, the flipped CNT arrays reached higher adhesion efficiency (the ratio of adhesion force to preload) with lower preload due to the higher compliance at the top surface of the arrays. With cyclic loading under micro mechanical tests, stiffening of the surface and declining of adhesion force were also observed. These results illustrated that the mechanical compliance at the region near the contact interface is the dominant factor for the adhesion performance of VACNT arrays.
RESUMO
G-triplexes have recently been identified as a new kind of DNA structures. They perhaps possess specific biological and chemical functions similar as identified G-quadruplex but can be formed by shorter G-rich sequences with only three G-tracts. However, until now, limited G-triplexes sequences have been reported, which might be due to the fact that their stability is one of the biggest concerns during their functional studies and application research. Herein, we found a G-rich sequence (5'-TGGGTAGGGCGGG-3') which can form a stable G-triplex (Tm â¼ 60 °C) at room temperature. The stable G-triplex can combine with thioflavin T and function as an efficient fluorescence light-up probe. Comparing with the traditional G-quadruplex based probe, this triplex based probe was easy to be controlled and excited. Finally, the probe was successfully applied into constructing a label-free molecular beacon for miRNA detection. Taking advantage of these abilities of the G-triplex based fluorescent probe, the challenges faced during designing G-rich sequences based fluorescent biosensors can be efficiently solved. These findings provide important information for the future application of G-triplex.
Assuntos
Benzotiazóis/química , DNA/química , Corantes Fluorescentes/química , Benzotiazóis/efeitos da radiação , DNA/efeitos da radiação , Fluorescência , Corantes Fluorescentes/efeitos da radiação , Luz , MicroRNAs/análise , Conformação de Ácido Nucleico , Espectrometria de Fluorescência/métodosRESUMO
Objective: This study is aim to discern the Traditional Chinese Medicine (TCM) syndrome classifications relevant to immunotherapy sensitive in non-small cell lung cancer (NSCLC) patients, and to delineate intestinal microbiota biomarkers and impact that wield influence over the efficacy of NSCLC immunotherapy, grounded in the TCM theory of "lung and large intestine stand in exterior-interior relationship." Methods: The study cohort consisted of patients with advanced NSCLC who received treatment at the Oncology Department of Chengdu Fifth People's Hospital. These patients were categorized into distinct TCM syndrome types and subsequently administered immune checkpoint inhibitors (ICIs), specifically PD-1 inhibitors. Stool specimens were collected from patients both prior to and following treatment. To scrutinize the differences in microbial gene sequences and species of the intestinal microbiota, 16S rRNA amplicon sequencing technology was employed. Additionally, peripheral blood samples were collected, and the analysis encompassed the assessment of T lymphocyte subsets and myeloid suppressor cell subsets via flow cytometry. Subsequently, alterations in the immune microenvironment pre- and post-treatment were thoroughly analyzed. Results: The predominant clinical manifestations of advanced NSCLC patients encompassed spleen-lung Qi deficiency syndrome and Qi-Yin deficiency syndrome. Notably, the latter exhibited enhanced responsiveness to ICIs with a discernible amelioration of the immune microenvironment. Following ICIs treatment, significant variations in microbial abundance were identified among the three strains: Clostridia, Lachnospiraceae, and Lachnospirales, with a mutual dependency relationship. In the subset of patients manifesting positive PD-L1 expression and enduring therapeutic benefits, the study recorded marked increases in the ratios of CD3+%, CD4+%, and CD4+/CD8+ within the T lymphocyte subsets. Conversely, reductions were observed in the ratios of CD8%, Treg/CD4+, M-MDSC/MDSC, and G-MDSC/MDSC. Conclusion: The strains Clostridia, Lachnospiraceae, and Lachnospirales emerge as potential biomarkers denoting the composition of the intestinal microbiota in the NSCLC therapy. The immunotherapy efficacy of ICIs markedly accentuates in patients displaying durable treatment benefits and those expressing positive PD-L1.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Microbioma Gastrointestinal , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Inibidores de Checkpoint Imunológico/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Antígeno B7-H1 , RNA Ribossômico 16S/genética , Imunoterapia , Receptor de Morte Celular Programada 1 , Pulmão , Microambiente TumoralRESUMO
Passive radiative cooling (PRC), as an electricity-free and environmentally friendly cooling strategy, is highly desirable in improving the global energy landscape. Despite numerous efforts, most designs for PRC are so devoted to improving the cooling performance in the daytime that they neglect the triggered overcooling at night. Herein, we approached an effective design for temperature-adaptive thermal management through integrating PRC and temperature control of room-temperature phase change material. Compared with conventional radiative coolers, the developed phase change material-enhanced radiative cooler (PCMRC) can adjust its performance according to the temperature of day and night. The PCMRC achieved an average subambient temperature drop of â¼6.3 °C under direct sunlight and an average temperature rise of â¼2.1 °C above ambient temperature at night, as well as a reduced temperature difference between day and night. The temperature-adaptive PCMRC shows great promise for passive radiative cooling regulation, which can further extend the applications of passive radiative cooling.
RESUMO
Objective.Intravascular optical coherence tomography is a useful tool to assess stent adherence and dilation, thus guiding percutaneous coronary intervention and minimizing the risk of surgery. However, each pull-back OCT images may contain thousands of stent struts, which are tiny and dense, making manual stent labeling slow and costly for medical resources.Approach. This paper proposed a multiple attention convolutional model for automatic stent struts detection of OCT images. Multiple attention mechanisms were utilized to strengthen the feature extraction and feature fusion capabilities. In addition, to precisely detect tiny stent struts, the model integrated multiple anchor frames to predict targets in the output.Main results. The model was trained in 4625 frames OCT images of 37 patients and tested in 1156 frames OCT images of 9 patients, and achieved a precision of 0.9790 and a recall of 0.9541, which were significantly better than mainstream convolutional models. In terms of detection speed, the model achieved 25.2 ms per image. OCT images from different collection systems, collection times, and challenging scenarios were experimentally tested, and the model demonstrated stable robustness, achieving precision and recall higher than 0.9630. Meanwhile, clear 3D construction of the stent was achieved.Significance. In conclusion, the proposed model solves the problems of slow manual analysis and occupying a large amount of medical manpower resources. It enhances the detection efficiency of tiny and dense stent struts, thus facilitating the application of OCT quantitative analysis in real clinical scenarios.
Assuntos
Intervenção Coronária Percutânea , Tomografia de Coerência Óptica , Humanos , Tomografia de Coerência Óptica/métodos , Stents , Vasos Coronários , Resultado do TratamentoRESUMO
PURPOSE: To evaluate the effect of microRNA (miR)-124 on osteogenic differentiation of dental pulp mesenchymal stem cells (DPSCs) and to explore the possible mechanism. METHODS: Logarithmic DPSCs were collected and divided into blank group, no-load group, miR-124 inhibitor group, miR-124 inhibitor combined with N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-ph (DAPT, Notch signaling pathway inhibitor) group. The blank group was not treated, the empty group was transfected with negative control vector inhibitor-NC, the miR-124 inhibitor group was transfected with miR-124 inhibitor, the miR-124 inhibitor combined with DAPT group was transfected with miR-124 inhibitor, and DAPT was added to make the final concentration of 5 µmol/L. The proliferation ability was tested by CCK-8 method 48 h after transfection. Alkaline phosphatase (ALP) activity was tested by p-nitrophenyl phosphate (P-NPP) method after 2 weeks of induction. The area of calcified nodules was tested by alizarin red staining method. The protein expression of hair-like division-related enhancer 1 (HEY1), hair-like division-related enhancer 2 (HEY2), and cyclin D1 gene (CCND1) were tested by Western blot. The data was analyzed by SPSS 19.0 software package. RESULTS: Compared with the blank group and no-load group, the A450 value at 24, 48, 72 h detected by CCK-8 experiment, A450 value of ALP activity, the area composition ratio of calcified nodules, and expression of HEY1, HEY2, and CCND1 in the miR-124 inhibitor group were increased (P<0.05). Compared with miR-124 inhibitor group, the A450 value at 24, 48, 72 h detected by CCK-8 experiment, A450 value of ALP activity, the area composition ratio of calcified nodules, and the expression of HEY1, HEY2, and CCND1 in the miR-124 inhibitor combined with DAPT group were significantly decreased(P<0.05). CONCLUSIONS: Down-regulation of miR-124 can promote osteogenic differentiation of DPSCs. It is speculated that the mechanism of action is related to the activation of Notch signaling pathway.
Assuntos
Células-Tronco Mesenquimais , MicroRNAs , Osteogênese/genética , Polpa Dentária/metabolismo , Inibidores da Agregação Plaquetária/metabolismo , MicroRNAs/metabolismo , Diferenciação Celular , Células-Tronco Mesenquimais/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células CultivadasRESUMO
Objective: To deeply understand the role expectation of clinical teachers for nursing master's degree graduates and use the crowd portrait intelligent data analysis system to assist in enrollment. Methods: Retrospective analysis was used to group nursing postgraduates and observe and statistically analyze the passing rate of basic course examination, subject achievement, graduation thesis, and graduation passing rate within three years. Results: The passing rates of the observation indexes of the double compliance group, the compliance system group, the compliance teacher group, and the double noncompliance group decreased in turn. It can be said that the system design can provide effective suggestions for the enrollment of nursing postgraduates. If the enrollment is carried out according to the system suggestions, the overall level of postgraduates can be improved, and their role expectations can be met. Conclusion: This paper was aimed at studying the advantages of using intelligent data systems to assist in enrollment, which can not only improve the overall level of nursing graduate students but also meet the role expectations of clinical teachers, systematically arrange practical teaching, and promote the development of relevant software systems.
Assuntos
Análise de Dados , Motivação , Humanos , Estudos Retrospectivos , EstudantesRESUMO
The present review aims to examine whether multi-component interventions for informal caregivers of people with dementia are effective on positive and negative aspects of caregiver well-being. Eleven databases were searched from inception to 8 March 2021. Only randomized controlled trials reporting the effectiveness of multi-component intervention on positive and negative aspects of caregiver well-being were eligible. Endnote X7 (Thomson ResearchSoft, Stanford, CA, USA) was used for study selection and version 5.1.0 of Cochrane Collaboration's tool (Cochrane, London, UK) was applied for quality assessment. Review Manager (Revman) Version 5.3 (Cochrane, London, UK) was used for the meta-analysis, and if statistical synthesis was inappropriate, only narrative analysis was performed. A total of 31 RCTs with 3939 participants were included. Meta-analyses showed small to moderate effects on subjective well-being, depression, and burden of caregivers, and a moderate to high effect on caregiver anxiety. Due to insufficient data and vast heterogeneity, meta-analysis was not performed for other outcomes, such as resilience, competence, and empathy. This review suggests that individualized multi-component interventions for caregivers may be one of the ways to promote their well-being. Further research is needed to explore the impact of rigorously designed and personalized multi-component interventions on informal caregivers, especially on more positive indicators, as well as its long-term effects and sustainability.
Assuntos
Cuidadores , Demência , Ansiedade , Transtornos de Ansiedade , Empatia , Humanos , Qualidade de VidaRESUMO
BACKGROUND: Long noncoding RNA (LncRNA) has been shown to mediate the development of human malignancies. However, data on its role in breast cancer remains scant. We aimed to evaluate the prognostic potential of lncRNAs in breast cancer. METHODS: We downloaded data on breast cancer patients from The Cancer Genome Atlas (TCGA) database. Tissues were obtained from The Fifth People's Hospital of Chengdu. We then used the DESeq2 package to profile the expression of the lncRNAs between the patients and normal samples. Besides, we performed prognosis and survival analysis using survival tools in R package. We then assayed the role of the differentially expressed lncRNAs, AC012213.3 (ENSG00000266289), in cancer cell lines. Quantitative real-time PCR and Western blot analysis were performed to evaluate the expression of the gene in the cell lines and then assessed its role in the progression of breast cancer using cell proliferation (CCK8 and colony formation assays), migration, invasion (transwell and wound-healing assays) and apoptotic (flow cytometry) assays. RESULTS: Our data showed high expression of lncRNA AC012213.3 in breast cancer tissues and cell lines. The high expression of the AC012213.3 was associated with the worse prognosis and clinical features. Besides, in vitro assays demonstrated that downregulation of AC012213.3 suppresses the proliferation and invasion of breast cancer cells. Further analysis showed that RAD54B is a downstream AC012213.3 target gene and was upregulated in breast cancer. Interestingly, RAD54B expression was associated with shorter survival in breast cancer. In addition, AC012213.3 was shown to facilitate breast cancer progression through the RAD54B/PI3K/AKT axis. CONCLUSION: Taken together, our data demonstrated that lncRNA AC012213.3 is upregulated in breast cancer and could enhance breast cancer progression through RAD54B/PI3K/AKT axis.
RESUMO
The dual-mode bio-imaging nanoprobe TP-CQDs@MnO2, based on two-photon carbon quantum dots and MnO2, has been developed for the two-photon fluorescence and MR imaging of endogenous H2O2 in the tumor microenvironment, and it achieved high selectivity, a great signal-to-noise ratio, a limit of detection (LOD) of 1.425 pM for H2O2, and a two-photon tissue penetration depth of 280 µm.
Assuntos
Peróxido de Hidrogênio/metabolismo , Imageamento por Ressonância Magnética , Microscopia Confocal , Nanoestruturas/química , Carbono/química , Linhagem Celular , Meios de Contraste/química , Humanos , Peróxido de Hidrogênio/análise , Limite de Detecção , Compostos de Manganês/química , Óxidos/química , Pontos Quânticos/química , Razão Sinal-Ruído , Espectrometria de Fluorescência , Microambiente TumoralRESUMO
Transferrin-modified AuNCs (Tf-AuNCs) with two photon-near infrared (TP-NIR) fluorescence were prepared. For the first time, a novel nanoprobe platform, Tf-AuNCs@MnO2, was developed for the TP-NIR fluorescence imaging and magnetic resonance imaging of living cells and tissues. This platform had high spatiotemporal resolution and a tissue-penetration depth of 300 µm.
Assuntos
Corantes Fluorescentes/química , Nanopartículas Metálicas/química , Transferrina/química , Corantes Fluorescentes/efeitos da radiação , Fluorometria , Glutationa/análise , Glutationa/metabolismo , Ouro/química , Ouro/efeitos da radiação , Humanos , Raios Infravermelhos , Células MCF-7 , Compostos de Manganês/química , Nanopartículas Metálicas/efeitos da radiação , Óxidos/química , FótonsRESUMO
Daytime passive radiative cooling is a promising electricity-free pathway for cooling terrestrial buildings. Current research interest in this cooling strategy mainly lies in tailoring the optical spectra of materials for strong thermal emission and high solar reflection. However, environmental heat gain poses a crucial challenge to building cooling at subambient temperatures. Herein, we devise a scalable thermal insulating cooler (TIC) consisting of hierarchically hollow microfibers as the building envelope that simultaneously achieves passive daytime radiative cooling and thermal insulation to reduce environmental heat gain. The TIC demonstrates efficient solar reflection (94%) and long-wave infrared emission (94%), yielding a temperature drop of about 9 °C under sunlight of 900 W/m2. Notably, the thermal conductivity of the TIC is lower than that of air, thus preventing heat flow from external environments to indoor space in the summer, an additional benefit that does not sacrifice the radiative cooling performance. A building energy simulation shows that 48.5% of cooling energy could be saved if the TIC is widely deployed in China.
RESUMO
Daytime radiative cooling is a passive strategy to cool down a terrestrial object under direct sunlight without the need of electricity input. It functions by simultaneously reflecting solar irradiance and sending heat as infrared (IR) thermal radiation through the atmospheric transparent window into the cold outer space. In spite of extensive studies on daytime radiative cooling, most of previous works were conducted in dry regions mainly in North America. Here, we explore the feasibility of achieving efficient radiative cooling in humid subtropical areas such as Hong Kong, where abundant atmosphere water vapor exists. In this case, the atmospheric transparent window is almost closed since water is highly absorptive of IR radiation. We report a simple approach to achieve efficient daytime radiative cooling in Hong Kong. Our design comprises an expanded polytetrafluoroethylene (ePTFE) film and a Ag layer deposited on a transparent glass substrate. We show that the combination of highly diffusely reflective ePTFE and all-band reflective Ag results in a reflectivity of 98% in the solar spectrum, allowing for a temperature drop up to 2.7 °C under a solar intensity of 1000 W/m2 on a humid day in Hong Kong.
RESUMO
Fluorescence detection technology has been widely concerned for its advantages of low cost, simple operation, good sensitivity, real-time and non-destructive biological imaging. However, most fluorophores emit bright fluorescence in solution, and the fluorescence decreases significantly in the high concentration or solid/aggregated state, which is called aggregation-caused quenching (ACQ). Cysteine (Cys) is an important kind of amino-acid in the field of bio-medicine, whose main function is to participate in metabolism and protein synthesis, detoxification, but intracellular cysteine concentrations (30-200 µM) are much low, and direct detection of endogenous cysteine is hampered by interference with other thiols. To solve the above problems, based on solid-state fluorophore HPQ, we for the first time prepared a novel solid-state fluorescence probe MA-HPQ, for monitoring of endogenous Cys, operated by the mechanism of excited intramolecular proton transfer (ESIPT). MeO-HPQ is completely insoluble in water, has very strong solid-state fluorescence with the maximum emission wavelength of 510 nm and the maximum excitation wavelength of 365 nm. This special property makes it very suitable for confocal microscopy compared with ordinary water-soluble fluorescent dyes. Due to the large Stokes shift (145 nm), MA-HPQ has very desirable advantages: reduced interference of background fluorescence, increased sensitivity, and enhanced contrast of biological imaging. More importantly, by preventing it from establishing internal hydrogen bonds, which is between imine nitrogen and phenolic hydroxyl groups, it can be made insoluble in water and have strong fluorescence properties, and the process is reversible. The ESIPT process can be blocked by masking phenolic hydroxyl, which can inhibit fluorescence to a large extent. In the presence of Cys, the probe reacts, releasing free MeO-HPQ, and begins to form a precipitated solid. The precipitated solid emitted bright green solid-state fluorescence, which was enhanced 43 times more than MA-HPQ. These results indicate that the probe MA-HPQ can be suitable to real spatiotemporal imaging of endogenous cysteine in HeLa cells. The excellent performance of the probe makes it applying for the visualization detection of endogenous cysteine in living cells and tissues with obtaining satisfactory results.
Assuntos
Cisteína , Corantes Fluorescentes , Cisteína/análise , Células HeLa , Humanos , Prótons , Espectrometria de FluorescênciaRESUMO
The specific host-guest interactions in the corresponding complexes of K+ and NH4+ with typical crown ethers were investigated by using FTIR and ultrafast IR spectroscopies. The counteranions, i.e., SCN-, were employed as a local vibrational probe to report the structural dynamics of the complexation. It was found that the vibrational relaxation dynamics of the SCN- was strongly affected by the cations confined in the cavities of the crown ethers. The time constant of the vibrational population decay of SCN- in the complex of NH4+ with the 18-crown-6 was determined to be 6 ± 2 ps, which is â¼30 times faster than that in the complex of K+ with the crown ethers. Control experiments showed that the vibrational population decay of SCN- depended on the size of the cavities of the crown ethers. A theoretical calculation further indicated that the nitrogen atom of SCN- showed preferential coordination to the K+ ions hosted by the crown ethers, while the NH4+ can form hydrogen bonds with the oxygen atoms in the studied crown ethers. The geometric constraints formed in the complex of crown ethers can cause a specific interaction between the NH4+ and SCN-, which can facilitate the intermolecular vibrational energy redistribution of the SCN-.
RESUMO
Vertically aligned carbon nanotube (CNT) arrays are promising candidates for advanced thermal interface materials (TIMs) since they possess high mechanical compliance and high intrinsic thermal conductivity. Some of the previous works indicate that the CNT arrays in direct dry contact with the target surface possess low contact thermal conductance, which is the dominant thermal resistance. Using a phase sensitive transient thermo-reflectance (PSTTR) technique, we measure the thermal conductance between CNT arrays and copper (Cu) surfaces under different pressures. The experiments demonstrated that the contact force is one of the crucial factors for optimizing the thermal performance of CNT array-based TIMs. The experimental results suggest that the Cu-CNT arrays' contact thermal conductance has a strong dependence on the surface deformation and has an order of magnitude rise as the contact pressure increases from 0.05 to 0.15 MPa. However, further increase of the contact pressure beyond 0.15 MPa has little effect on the contact thermal resistance. This work could provide guidelines to determine the minimum requirement of packaging pressure on CNT TIMs.
RESUMO
A combinatorial chemistry method was employed to screen the yellow phosphors of (Lu1â(x)Gd(x))3Al5O12:Ce3(y) as luminescent materials. An array of 81 compositions was synthesized by inkjetting nitrate solutions into microreactor wells and sintering at high temperature. The candidate formulations were evaluated by luminescence pictures, and the optimal composition was determined to be Lu(2.7)Gd(0.3)Al(5)O(12):Ce(0.045) after scale-up and detailed characterization. Lu2.7Gd0.3Al5O12:Ce0.045 was also found to have a short decay time (≤53.97 ns). These results demonstrate the great potential of the Lu2.7Gd0.3Al5O12:Ce0.045 as a component of ceramic scintillators.