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1.
Nanomicro Lett ; 16(1): 69, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38175419

RESUMO

The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO2 nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation (21° s-1) and enhanced photothermal efficiency (increase by 3.7 °C s-1 under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca2+ endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity (gauge factor 3.94 within a wide strain range of 600%), fast response times (140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human-machine interactions.

2.
Int J Biol Macromol ; 257(Pt 2): 128757, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38092123

RESUMO

Hydrogels from natural polymers are eco-friendly, biocompatible and adjustable for manufacturing wearable sensors. However, it is still challenging to prepare natural polymer hydrogel sensors with excellent properties (e.g., high conductivity). Here, we developed a physically cross-linked, highly conductive and multifunctional hydrogel (named PPTP) to address this challenge. The natural renewable pectin-based PPTP hydrogel is synthesized by introducing tannic acid (TA), calcium chloride (CaCl2), and sodium chloride (NaCl) into the pectin/polyvinyl alcohol (PVA) dual network structure. The hydrogel exhibits excellent characteristics, including unique tensile strength (2.6155 MPa), high electrical conductivity (7 S m-1), and high sensitivity (GF = 3.75). It is also recyclable, further enhancing its eco-friendly nature. The PPTP hydrogel can be used for monitoring human joint activities, as flexible electrodes for monitoring electrocardiogram (ECG) signals, and touchable screen pen for electronic skin. Moreover, when combined with Morse code and wireless Bluetooth technology, PPTP hydrogels can be used for underwater and land information encryption, and decryption. Our unique PPTP hydrogel offers promising opportunities for medical monitoring, information transfer, and human-computer interaction.


Assuntos
Hidrogéis , Pectinas , Polifenóis , Humanos , Polissacarídeos , Condutividade Elétrica , Polímeros , Cloreto de Sódio
3.
Front Psychiatry ; 14: 1178834, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37575569

RESUMO

Objective: The prevalence of mental distress has been noted in shelter hospitals set up for COVID-19. Potential risk demographic and hospitalization factors were screened. We also aimed to determine whether humanistic care established in the shelter hospital was effective in ameliorating mental distress. Methods: A cross-sectional observational survey-based single-centered study was conducted from 28th April to 5th May 2022 during the COVID-19 pandemic in Shanghai. Asymptomatic adult inpatients and those with mild symptoms were recruited for this study, and humanistic care measures were carried out by the administrative office according to the Work Program on Psychological Assistance and Social Work Services at the Shelter Hospital launched on 5th March 2020. Symptoms of mental distress, such as reported stress, anxiety, depression, and insomnia were measured using the Chinese Stress Response Questionnaire-28, the Chinese version of Generalized Anxiety Disorder-7, Patient Health Questionnaire-9, and Insomnia Severity Index-7, respectively. Results: In total, 1,246 out of 9,519 inpatients, including 565 (45.35%) women and 681 (54.65%) men, with a median age of 36 years responded to the survey. The overall prevalence of stress, anxiety, depression, and insomnia in inpatients was 94 (7.54%), 109 (8.75%), 141 (11.32%), and 144 (11.56%), respectively. Mental distress was aggravated by COVID-19-related symptoms, comorbidities, and prolonged hospital stays. A stable internet connection was the most effective measure to reduce stress and depression. Offering inpatient with study or work facilitations, and mental health education help to ameliorate anxiety and depression. Organizing volunteering was a potential protective factor against stress. Conclusion: Humanistic care is crucial and effective for protecting against mental distress, which should be emphasized in shelter hospitals.

4.
ACS Appl Mater Interfaces ; 15(19): 23653-23661, 2023 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-37155934

RESUMO

An energy-saving scheme that can simultaneously realize electromagnetic interference (EMI) shielding, passive solar radiative heating, and active Joule heating in a single wearable device is still a huge challenge. Here, by combining the unique properties of Ti3C2Tx MXene and biocompatible cellulose nanofibers (CNFs), a flexible, degradable, and antibacterial multifunctional Ti3C2Tx/CNF paper (∼0.6 Ω/sq) is constructed through a facile vacuum filtration strategy. The resultant device not only exhibits an admirable EMI shielding effectiveness of ∼48.5 dB at the X-band and a superior heating property including dual-driven electrothermal and photothermal conversion without energy but also possesses wide temperature range regulation and long-time stability. More impressively, both high antibacterial efficiency (toward both gram-positive and gram-negative bacteria) and good degradability with low-concentration hydrogen peroxide solution can also be achieved in Ti3C2Tx/CNF papers. This study provides a promising platform for practical applications of multifunctional Ti3C2Tx/CNFs in EMI shielding, thermotherapy, heat preservation, and antibacterial protection in harsh environments, satisfying the demands for energy-saving, environmentally friendly, and sustainable development.


Assuntos
Antibacterianos , Bactérias Gram-Negativas , Antibacterianos/farmacologia , Bactérias Gram-Positivas , Titânio , Celulose , Fenômenos Eletromagnéticos
5.
Phys Chem Chem Phys ; 25(14): 10175-10183, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36976635

RESUMO

The exfoliated two-dimensional (2D) Ga2O3 opens new avenues to fine-tune the carrier and thermal transport properties for improving the electro-thermal performance of gallium oxide-based power electronics with their enhanced surface-to-volume ratios and quantum confinement. Yet, the carrier transport in 2D Ga2O3 has not been fully explored, especially considering their large Fröhlich coupling constants. Herein, we mainly investigate the electron mobility of monolayer (ML) and bilayer (BL) Ga2O3 from first-principles by adding polar optical phonon (POP) scattering. The results show that POP scattering is the dominant factor limiting the electron mobility for 2D Ga2O3, accompanied by a large 'ion-clamped' dielectric constant Δε. The value of Δε is 3.77 and 4.60 for ML and BL Ga2O3, respectively, indicating a large change in polarization in the external field. The electron mobility of 2D Ga2O3 enhances with increasing thickness despite the enhanced electron-phonon coupling strength and Fröhlich coupling constant. The predicted electron mobility for BL and ML Ga2O3 at a carrier concentration of 1.0 × 1012 cm-2 is 125.77 cm2 V-1 s-1 and 68.30 cm2 V-1 s-1 at room temperature, respectively. This work aims to unravel the scattering mechanisms beneath engineering electron mobility of 2D Ga2O3 for promising applications in high-power devices.

6.
ACS Appl Mater Interfaces ; 15(13): 16631-16639, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36943938

RESUMO

In order to selectively oxidize benzyl alcohol, a novel noble metal catalyst based on polymer ionic liquids with a core-shell structure was created. First, polymer ionic liquid microspheres (PILMs) were prepared by free radical polymerization. Second, the in situ adsorption of Au nanoparticles on the surface of PILMs was accomplished, thanks to the strong electrostatic interaction between N atoms and metal ions on the diazole ring of PILMs. Additionally, the introduction of Al(OH)3 prevented the aggregation of Au nanoparticles and promoted the catalytic reaction. Finally, the PILM/Au/Al(OH)3 catalyst with a core-shell structure was formed. The effectiveness of the PILM/Au/Al(OH)3 catalyst was assessed by varying the catalyst's type, quantity, amount of Au, amount of H2O2, temperature, and reaction time. After five cycles of experiments, the catalyst was effective and reusable. In addition, the potential catalytic mechanism of the catalyst in the oxidation of benzyl alcohol was proposed.

7.
Materials (Basel) ; 16(3)2023 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-36770139

RESUMO

The electromigration behavior of microbumps is inevitably altered under bidirectional currents. Herein, based on a designed test system, the effect of current direction and time proportion of forward current is investigated on Cu Pillar/Ni/Sn-1.8 Ag/Cu microbumps. Under thermo-electric stressing, microbumps are found to be susceptible to complete alloying to Cu6Sn5 and Cu3Sn. As a Ni layer prevents the contact of the Cu pillar with the solder, Sn atoms mainly react with the Cu pad, and the growth of Cu3Sn is concentrated on the Cu pad sides. With direct current densities of 3.5 × 104 A/cm2 at 125 °C, the dissolution of a Ni layer on the cathode leads to a direct contact reaction between the Cu pillar and the solder, and the consumption of the Cu pillar and the Cu pad shows an obvious polarity difference. However, with a bidirectional current, there is a canceling effect of an atomic electromigration flux. With current densities of 2.5 × 104 A/cm2 at 125 °C, as the time proportion of the forward current approaches 50%, a polarity structural evolution will be hard to detect, and the influence of the chemical flux on Cu-Sn compounds will be more obvious. The mechanical properties of Cu/Sn3.0Ag0.5Cu/Cu are analyzed at 125 °C with direct and bidirectional currents of 1.0 × 104 A/cm2. Compared with high-temperature stressing, the coupled direct currents significantly reduced the mechanical strength of the interconnects, and the Cu-Sn compound layers on the cathode became the vulnerable spot. While under bidirectional currents, as the canceling effect of the electromigration flux intensifies, the interconnect shear strength gradually increases, and the fracture location is no longer concentrated on the cathode sides.

8.
Phys Chem Chem Phys ; 25(9): 6746-6756, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36807438

RESUMO

Nanoscale thermal transport at solid-liquid interfaces plays an essential role in many engineering fields. This work performs deep potential molecular dynamics (DPMD) simulations to investigate thermal transport across copper-water interfaces. Unlike traditional classical molecular dynamics (CMD) simulations, we independently train a deep learning potential (DLP) based on density functional theory (DFT) calculations and demonstrated its high computational efficiency and accuracy. The trained DLP predicts radial distribution functions (RDFs), vibrational densities of states (VDOS), density curves, and thermal conductivity of water confined in the nanochannel at a DFT accuracy. The thermal conductivity decreases slightly with an increase in the channel height, while the influence of the cross-sectional area is negligible. Moreover, the predicted interfacial thermal conductance (ITC) across the copper-water interface by DPMD is 2.505 × 108 W m-2 K-1, the same order of magnitude as the CMD and experimental results but with a high computational accuracy. This work seeks to simulate the thermal transport properties of solid-liquid interfaces with DFT accuracy at large-system and long-time scales.

9.
Microsyst Nanoeng ; 8: 119, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36389055

RESUMO

Gallium nitride high electron mobility transistor (GaN HEMT) devices have become critical components in the manufacturing of high-performance radio frequency (RF) or power electronic modules due to their superior characteristics, such as high electron saturation speeds and high power densities. However, the high heat characteristics of GaN HEMTs make device level cooling a critical problem to solve since performance degradation or even failure may occur under high temperatures. In this paper, we proposed a 2.5D integration method with device-level microchannel direct cooling for a high-power GaN HEMT device. To demonstrate this technological concept, a multigate GaN HEMT device featuring a gate length/width/source drain spacing of 0.5 µm/300 µm/6 µm that underwent in-house backside thinning and metallization was used as the test vehicle. A high-resistivity silicon (HR Si) interposer embedded with four-layer microchannels was designed, having widths/pitches of 30 µm/30 µm at the top microchannel. The high-power GaN HEMT device was soldered on a Si interposer embedded with open microchannels for heat dissipation. A pair of GSG Pad chips was soldered simultaneously to display the capacity for the heterogeneous integration of other chip types. Thermal property evaluation was conducted with experiments and simulations. The test results showed that the maximum surface temperature of the GaN HEMT device decreased to 93.8 °C when it experienced a heat dissipation density of 32 kW/cm2 in the gate finger area and an average heat dissipation density of 5 kW/cm2 was found in the active area with the DI water coolant at a flow rate of 3 mL/min. To our knowledge, among recently reported works, this finding was the best cooling capacity of heterogeneously integrated microchannels for GaN HEMT devices. In addition, this technology was scalable regarding the numbers of gate fingers or GaN HEMT devices.

10.
Front Public Health ; 10: 924488, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36262225

RESUMO

Background: Many studies have explored the association between diabetes and nocturia, but it remains unclear. This article systematically analyses existing evidence of the relationship between diabetes and nocturia, including subgroup analysis based on the number of voids, gender, and continent, in the hope of reaching more reliable clinical conclusions relating to diabetes and nocturia. Methods: PubMed, Web of Science, and Cochrane Library were searched for identifying studies relating to diabetes and nocturia prior to July 2021. Literature quality evaluation was performed using the Newcastle Ottawa Scale. A random effect meta-analysis was used for pooled odds ratios (ORs) and confidence intervals (CIs) as a means of evaluating the relationship between diabetes and nocturia. Results: In total, 29 of 781 potentially relevant studies were proven to be eligible. The overall pooled OR demonstrated that diabetes increases the risk of nocturia (OR: 1.49; 95% CI: 1.38, 1.61; P < 0.00001). The association was found to be more robust among subjects ≥ 1 void than ≥ 2 void (OR: 1.74; 95% CI: 1.41, 2.14; P < 0.00001 vs. OR: 1.45; 95% CI: 1.33, 1.59; P < 0.00001), in males than females (OR: 1.59; 95% CI: 1.41, 1.79; P < 0.00001 vs. OR: 1.41; 95% CI: 1.20, 1.66; P < 0.0001) and in Asia than Europe or North America (OR: 1.54; 95% CI: 1.36, 1.75; P < 0.00001 vs. OR: 1.43; 95% CI: 1.19, 1.72; P = 0.0001 vs. OR: 1.45; 95% CI: 1.22, 1.73; P < 0.0001). Conclusions: Diabetes has an association with a 1.49-fold higher risk of nocturia. This association is more robust for Asian and male subjects or those at a lower nocturia cut-off.


Assuntos
Diabetes Mellitus , Noctúria , Masculino , Humanos , Noctúria/epidemiologia , Diabetes Mellitus/epidemiologia , Europa (Continente) , Ásia , América do Norte
11.
Pain Res Manag ; 2022: 8648584, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35619991

RESUMO

Background: Chronic low back pain (CLBP) is a clinically common and expensive disease. Patients frequently take sick leaves because of pain and dysfunction, and their unpleasant life and work experiences cause psychological depression and anxiety and affect their quality of life. Sleep disturbance is a common problem among patients with low back pain (LBP) with more than 50% complaining about poor sleep quality. This study aimed to explore the correlations between anxiety, sleep quality, and pressure-pain threshold (PPT) and their differences between patients with CLBP and asymptomatic people. Methods: Forty patients with CLBP and 40 asymptomatic people were recruited. Relevant data, including State-Trait Anxiety Inventory, Pittsburgh Sleep Quality Index, and PPT, were individually and independently collected by blinded physiotherapists with a practicing certificate and then statistically analyzed. An independent sample t-test was used to determine the intergroup differences between patients with CLBP and asymptomatic populations. Pearson correlation coefficient was employed for correlation analysis. Results: The CLBP group had significantly higher anxiety scores (41.64 ± 9.88 vs. 36.69 ± 8.31; t = -2.496, p=0.015) than the asymptomatic group. A significant difference was found in the total score of the Pittsburgh Sleep Quality Index (6.41 ± 2.43 vs. 5.09 ± 2.18; t = -2.628, p=0.010) but not in the trait anxiety (44.00 ± 7.83 vs. 42.67 ± 9.51; t = -0.695, p=0.489) of the two groups. State-Trait Anxiety Inventory showed a low to moderate negative correlation with PPT. No remarkable correlation was observed between Pittsburgh Sleep Quality Index and PPT. Conclusions: Patients with CLBP showed considerably worse state anxiety and sleep quality than asymptomatic people; however, no substantial difference in PPT was found between the two groups. The results suggest that in clinical practice, the focus should include pain and related social and psychological factors. CLBP treatment could be considered from multiple perspectives and disciplines.This trial is registered with Chinese Clinical Trial Registry (Trial registration: ChiCTR-TRC-13003701).


Assuntos
Dor Lombar , Ansiedade/etiologia , Ansiedade/psicologia , Humanos , Limiar da Dor , Qualidade de Vida/psicologia , Qualidade do Sono
12.
Artigo em Inglês | MEDLINE | ID: mdl-35310022

RESUMO

Objective: To reduce the pain of quadriceps during knee flexion after total knee arthroplasty and increase range motion of knee flexion. Design: Three-month prospective before/after quality improvement project. Setting. Department of Bone and Joint Surgery. Participants. A total of 80 patients who met the surgical indications were admitted to the outpatient department for surgery. They were randomly grouped by computer in advance, and the patients were divided into two groups according to the time of admission, each with 40 cases. Intervention. The intervention group performed routine rehabilitation exercises and received quadriceps acupoint massages for 20 minutes twice a day for two consecutive weeks. The control group performed routine rehabilitation exercises, such as gentle quadriceps massage for 20 minutes twice a day for two consecutive weeks. Main Outcome Measures. PPT (pressure pain threshold) of quadriceps femoris/VAS (visual analog scale) of knee flexion and motion of knee flexion. Results: The VAS score, range of motion, and tenderness threshold during flexion were significantly better in the intervention group than in the control group at 1, 2, and 4 weeks after surgery. But the VAS score, range of motion, and tenderness threshold did not significantly differ between groups at 12 weeks after surgery. Conclusion: Acupoint massage of the quadriceps femoris can relieve early flexion pain in patients after total knee arthroplasty. The trial was registered at clinical trials.gov.

13.
Front Pediatr ; 10: 938810, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36683812

RESUMO

Recently, mental health has received increasing attention, particularly preoperative anxiety, which constitutes a bad emotional experience for surgical patients. Many experts have studied preoperative anxiety in terms of its related risk factors, interventions, and postoperative effects; however, there has been no systematic analysis of published articles. This paper presents a bibliometric review of documents related to preoperative anxiety published between 2001 and 2021. A detailed data analysis of 1,596 publications was conducted using CiteSpace and VOSviewer. Since the 20th century, the field of preoperative anxiety has gradually developed; research began around 2000 and has made a huge leap forward since 2016. Developed countries, led by the United States, were the first to conduct research, but preoperative anxiety research in developing countries like Turkey and China has gradually increased and led to an irreplaceable contribution. Intervention has remained the main topic of preoperative anxiety research, and measures have developed from premedication to the provision of education and information. Moreover, the use of advanced equipment such as virtual reality has emerged with great popularity. Based on previous research, the application of virtual reality combined with pediatric patients will become a new research direction.

14.
J Am Chem Soc ; 143(37): 15011-15016, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34516737

RESUMO

The synthesis of three-dimensional (3D) covalent organic frameworks (COFs) requires high-connectivity polyhedral building blocks or the controlled alignment of building blocks. Here, we use the latter strategy to assemble square-planar cobalt(II) phthalocyanine (PcCo) units into the nbo topology by using tetrahedral spiroborate (SPB) linkages that were chosen to provide the necessary 90° dihedral angles between neighboring PcCo units. This yields a porous 3D COF, SPB-COF-DBA, with a noninterpenetrated nbo topology. SPB-COF-DBA shows high crystallinity and long-range order, with 11 resolved diffraction peaks in the experimental powder X-ray diffraction (PXRD) pattern. This well-ordered crystal lattice can also be imaged by using high-resolution transmission electron microscopy (HR-TEM). SPB-COF-DBA has cubic pores and exhibits permanent porosity with a Brunauer-Emmett-Teller (BET) surface area of 1726 m2 g-1.

15.
BMC Sports Sci Med Rehabil ; 13(1): 35, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33794983

RESUMO

BACKGROUND: Therapeutic training is the most commonly used treatment methods for chronic low back pain (CLBP), and the use of a pressure biofeedback unit for transversus abdominis muscle (TrA) training is one of the core muscle training methods. The study aim of this research is to explore the effects of different intensities (sham training, low-intensity and high-intensity) of TrA muscle training on people with CLBP in pressure-pain threshold (PPT). METHODS: A total of 45 patients with CLBP were recruited, of whom 44 were included in the analysis. Fifteen, 14, and 15 were included in the sham training group, the low-intensity group, and the high-intensity group, respectively. A pressure biofeedback unit was used in performing a one-time TrA training intervention involving 30 times of 180 mmHg TrA contraction training at high intensity for 10 min and 15 times of 100 mmHg TrA contraction training at low intensity for 5 min. The sham training group completed comfort exercises and did not undergo training. The evaluation indicators were as follows: PPT, short-form McGill pain questionnaire, and body surface pain radiation. RESULTS: High-intensity training could activate more waist core muscles than low-intensity training. Significant changes on PPT (units: kgf) were observed in the following four muscles immediately after high-intensity training: iliopsoas [0.69 (0.13-1.25) 95% CI, p = 0.020]; quadratus lumborum [0.84 (0.23-1.45) 95% CI, p = 0.012]; erector spinae [0.66 (0.18-1.15) 95% CI, p = 0.011]; transversus abdominis [0.70 (0.26-1.14) 95% CI, p = 0.004], and in three muscles after low-intensity training: quadratus lumborum [0.61 (0.17-1.05) 95% CI, p = 0.009]; transversus abdominis [0.14 (from - 0.15 to 0.43) 95% CI, p = 0.022]; piriformis [0.55 (0.13-0.98) 95% CI, p = 0.014]. The change in body surface pain radiation immediately after exercise was [- 10.87 (from - 17.51 to - 4.22) 95% CI, p = 0.003] for high-intensity training and [- 5.21 (from - 9.40 to - 1.03) 95% CI, p = 0.019] for low-intensity training. CONCLUSIONS: TrA training could increase the PPT of the waist core muscles and reduce the radiation range of waist pain. The benefits of high-intensity training are higher than those of low-intensity training. TRIAL REGISTRATION: ChiCTR-TRC-13003701 . Registered 18 October 2013. Code of ethical approval: 2018069.

16.
Materials (Basel) ; 15(1)2021 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-35009255

RESUMO

The grain orientation of Sn-based solder joints on copper pillars under the combined action of electron wind force and temperature gradient greatly affects their electromigration damage. The copper pillars with Sn-1.8Ag lead-free solder on the top was subjected to a current density of 1.5 × 104 A/cm2 at 125 °C to study the electromigration behaviors. The grain orientation was characterized by scanning electron microscopy (SEM) equipped with electron backscattered diffraction (EBSD) detector. Metal dissolution and voids formation in the cathode as well as massive intermetallic compounds(IMC) accumulation in the anode were observed after electromigration. Closer examination of solder joints revealed that the Sn grain whose c-axis perpendicular to electric current may have retarded Cu diffusion to anode and IMC accumulation. In addition, the newly formed Cu6Sn5 exhibited preferred orientation related to the electric current direction.

17.
Materials (Basel) ; 13(23)2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33276575

RESUMO

The in-situ observation of Sn-3.0Ag-0.5Cu solder joints under electromigration was conducted to investigate the microstructure and grain orientation evolution. It was observed that there was a grain rotation phenomenon during current stressing by in-situ electron backscattered diffraction (EBSD). The rotation angle was calculated, which indicated that the grain reorientation led to the decrease of the resistance of solder joints. On the other hand, the orientation of ß-Sn played a critical role in determining the migration of Cu atoms in solder joints under current stressing migration. When the angle between the electron flow direction and the c-axis of Sn (defined as α) was close to 0°, massive Cu6Sn5 intermetallic compounds were observed in the solder bulk; however, when α was close to 90°, the migration of the intermetallic compound (IMC) was blocked but many Sn hillocks grew in the anode. Moreover, the low angle boundaries were the fast diffusion channel of Cu atoms while the high grain boundaries in the range of 55°-65° were not favorable to the fast diffusion of Cu atoms.

18.
Sci Total Environ ; 724: 138187, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408447

RESUMO

Chlorophenols (CPs) are important pollutants detected frequently in the environment. This study intended to detect the inhibitory effects of fourteen CPs (2-CP, 3-CP, 4-CP, 4C2AP, 4C3MP, 2.4-DCP, 2.3.4-TCP, 2.4.5-TCP, 2.4.6-TCP, 3.4.5-TCP, 2.3.4.5-TECP, 2.3.4.6-TECP, 2.3.5.6-TECP and PCP) towards human liver cytochrome P450 3A4 (CYP3A4). Throughout the tests, testosterone was used as the probe substrate and CPs were used as inhibitors. A series of experiments (enzyme activity assays, preliminary screening tests, inhibition kinetics determination) were conducted to determine the inhibition of CPs towards human liver CYP3A4. CPs with the inhibitory effect >80% were selected for the inhibition evaluation in liver microsomes from different animal species (monkey, rat, dog, pig). The results showed that 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP inhibited the activities of CYP3A4 by 80.3%, 93.4%, 91.6%, respectively. Inhibition kinetics type were non-competitive and inhibition kinetics constant (Ki) values were 26.4 µM, 13.5 µM, and 8.8 µM for the inhibition of 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP towards human CYP3A4, respectively. Inhibition kinetics type was competitive and Ki value was 4.9 µM for the inhibition of 2.3.4-TCP towards CYP3A4 in Monkey liver microsomes (MyLMs). Inhibition kinetic types were non-competitive and Ki values were 8.1 µM and 28.7 µM for the inhibition of 3.4.5-TCP and 2.3.4.5-TECP towards CYP3A4 in MyLMs. Inhibition kinetic types were non-competitive and Ki values were 13.8 µM, 0.6 µM, and 6.1 µM for the inhibition of 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP towards CYP3A4 in Dog liver microsomes (DLMs), respectively. By comparing Ki values and inhibition kinetic types, the dog was the most suitable model to assess the inhibition of 2.3.4-TCP and 2.3.4.5-TECP towards CYP3A4, and monkey was the most suitable model to assess the inhibition of 3.4.5-TCP towards CYP3A4. In conclusion, our recent study on the inhibition of CPs towards CYP3A4 and species differences was important for further toxicological studies of CPs in human bodies.


Assuntos
Clorofenóis , Inibidores das Enzimas do Citocromo P-450 , Animais , Citocromo P-450 CYP3A , Sistema Enzimático do Citocromo P-450 , Cães , Humanos , Microssomos Hepáticos , Ratos , Suínos
19.
Chem Sci ; 11(2): 543-550, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-32206271

RESUMO

Photocatalytic conversion of CO2 into fuels is an important challenge for clean energy research and has attracted considerable interest. Here we show that tethering molecular catalysts-a rhenium complex, [Re(bpy)(CO)3Cl]-together in the form of a crystalline covalent organic framework (COF) affords a heterogeneous photocatalyst with a strong visible light absorption, a high CO2 binding affinity, and ultimately an improved catalytic performance over its homogeneous Re counterpart. The COF incorporates bipyridine sites, allowing for ligation of the Re complex, into a fully π-conjugated backbone that is chemically robust and promotes light-harvesting. A maximum rate of 1040 µmol g-1 h-1 for CO production with 81% selectivity was measured. CO production rates were further increased up to 1400 µmol g-1 h-1, with an improved selectivity of 86%, when a photosensitizer was added. Addition of platinum resulted in production of syngas, hence, the co-formation of H2 and CO, the chemical composition of which could be adjusted by varying the ratio of COF to platinum. An amorphous analog of the COF showed significantly lower CO production rates, suggesting that crystallinity of the COF is beneficial to its photocatalytic performance in CO2 reduction.

20.
J Environ Manage ; 255: 109859, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32063319

RESUMO

China's paper industry development is rapid, but the recycling rate of China's waste paper has been low all the time. Meanwhile, material flow analysis can help determine the flow of waste paper, and life cycle assessment (LCA) is the methodological framework for quantifying greenhouse gas emissions. Therefore, present study integrates these two methods into the model construction of China's waste paper recycling decision system. Present study constructs a benchmark model of China's waste paper recycling decision system in 2017, focusing on the impact of nonstandard waste paper recycling on the economic and environmental benefits of China's domestic waste paper recycling system. This model construction is followed by sensitivity analysis of the relevant parameters affecting the efficiency of the waste paper recycling system. Finally, present study forecasts the system's economic benefits and greenhouse gas (GHG) emissions in the context of integrating and regulating nonstandard recycling vendors. The results show that the economic benefit of China's waste paper recycling in 2017 is approximately 458.3 yuan/t and that the GHG emissions are 901.1 kgCO2eq. The standard recovery rate and nonstandard recovery acceptance rate will both have a significant impact on the system's economic benefits and improve the GHG emissions structure. In the context of integrating nonstandard recycling enterprises and individual recycling vendors, the economic benefits will rise to 3312.5 yuan/t in 2030, while GHG emissions will rise to 942.9 kgCO2eq. Present study can play a certain guiding role for policy makers in formulating waste paper recycling industry specifications and formulating relevant policies.


Assuntos
Gases de Efeito Estufa , Reciclagem , China , Efeito Estufa , Indústrias
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