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1.
Ann Cardiothorac Surg ; 13(4): 364-375, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39157184

RESUMO

Background: The difficulty of suturing perfect anastomoses in limited-access conditions prevents the transition of traditional coronary artery bypass grafting (CABG) to sternal-sparing approaches, even in the robotic era. Automated coronary anastomotic connector technologies may address these difficulties, but to date, none have achieved broad adoption. Besides versatility, ease-of-use and cost-effectiveness, the key performance parameter of such technology is anastomotic patency. In this meta-analysis, we aim to evaluate published connector devices by examining their patency outcomes in distal anastomoses. Methods: The literature was systematically searched for studies comparing the angiographic patency of connector constructed coronary anastomoses to handsewn (HS) connections in adult patients undergoing CABG. The primary outcome was anastomosis patency across early (<30 days), mid-term (30 days to 1 year) and long-term (>1 year) follow-up. Random-effects meta-analyses were employed to analyze and compare patency using pooled risk ratios (RR) with 95% confidence intervals (CI). Results: The search yielded 14 studies concerning eight connector devices. In 4,311 patients, a total of 4,328 anastomoses were constructed, 674 with connector devices and 3,654 with a HS technique. The pooled device patency over all timeframes was non-inferior to the HS technique (RR 0.90, 95% CI: 0.56-1.44). Technologies having a relatively large blood-exposed non-intimal surface area (BENIS, >15 mm2) performed acceptably when applied to large target vessels [>2.0-2.5 mm inner diameter (ID)]. A tiny anastomotic orifice area (AOA, < ca. 4 mm2) appeared to adversely affect results. Technologies realizing a generous AOA in combination with a limited BENIS showed superior results and applicability by performing well across the entire range of target coronary artery diameters (>1.0-1.5 mm ID). Conclusions: The overall results suggest that connectors yield at least non-inferior anastomosis patency outcomes compared to HS techniques in all observed timeframes. Optimizing device characteristics like BENIS and AOA appear fundamental for broad applicability.

2.
Int J Mol Sci ; 25(15)2024 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-39126049

RESUMO

T5 is a siphophage that has been extensively studied by structural and biochemical methods. However, the complete in situ structures of T5 before and after DNA ejection remain unknown. In this study, we used cryo-electron microscopy (cryo-EM) to determine the structures of mature T5 (a laboratory-adapted, fiberless T5 mutant) and urea-treated empty T5 (lacking the tip complex) at near-atomic resolutions. Atomic models of the head, connector complex, tail tube, and tail tip were built for mature T5, and atomic models of the connector complex, comprising the portal protein pb7, adaptor protein p144, and tail terminator protein p142, were built for urea-treated empty T5. Our findings revealed that the aforementioned proteins did not undergo global conformational changes before and after DNA ejection, indicating that these structural features were conserved among most myophages and siphophages. The present study elucidates the underlying mechanisms of siphophage infection and DNA ejection.


Assuntos
Microscopia Crioeletrônica , DNA Viral , Ureia , DNA Viral/genética , Ureia/farmacologia , Ureia/química , Modelos Moleculares , Proteínas Virais/química , Proteínas Virais/metabolismo
3.
Med J Armed Forces India ; 80(4): 442-448, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39071759

RESUMO

Background: Few studies have established the relationship between connector widths, cuspal angulation, loading forces, and supporting structures of zirconia fixed dental prosthesis (FDP). The objective of the study was to compare the stress distribution in implant- and tooth-supported zirconia FDP with different connector designs, and cuspal angulations of replaced teeth under diverse angulations of forces. Methods: Finite element (FE) analysis was done by simulating a 3-unit implant- and tooth-supported FDP. FE models with varying cuspal angulations 0°, 20°, and 33° and connector designs 2 mm, 2.5 mm, and 3 mm was generated. The simulated models were loaded with 100 N of forces under different axial and non-axial angulations. The graphical and numerical stresses were observed, recorded, and statistically analyzed. Results: Higher stress of 245.55 MPa in implant-supported FDP and lower stress value of 28.22 MPa in tooth-supported FDP was observed at 0-cuspal inclination for 3 mm connector width. The data were statistically analyzed with unpaired t test to eliminate the differences. The inter-group, intra-group tests, p and t values for various connector, and tooth angulations of tooth- and implant-supported FDP were statistically insignificant. (p > 0.05). Conclusion: There was no statistically significant difference in stress was observed between tooth- and implant-supported FDP for different connector widths, cuspal inclination, and diverse angulation of forces.

5.
Materials (Basel) ; 17(14)2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39063800

RESUMO

Traditional stud and perfobond leiste (PBL) shear connectors are commonly used as load-transferring components in steel-concrete composite structures. Composite shear connectors fully utilize the advantages of traditional stud and PBL shear connectors. In order to maximize the advantages of composite shear connectors, a novel shear connector for complex environments was proposed. The steel-FRP composite bars (SFCBs) with excellent fatigue resistance and corrosion resistance were introduced to replace the steel bars. This study discussed the failure modes, load-slip curves, and load-strain curves of the composite shear connector. In addition, a finite element analysis (FEA) model was developed to analyze the influence of various factors on its shear behavior. Results showed that compared with traditional composite shear connectors, the introduction of SFCB resulted in a promotion of 7.85% in shear stiffness, and it also led to a significant increase of 63.61% in ductility, further enhancing the mechanical performance. Meanwhile, FEA models were well fitted to the test results, and parametric analysis showed variate effects on shear bearing capacity. In the end, an equation was established to calculate the shear capacity of composite shear connectors, which could provide a reference for further research and engineering applications.

6.
Cureus ; 16(6): e61662, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38966438

RESUMO

Introduction Peripheral intravenous (IV) administration sets are a source of infection that increases morbidity, mortality, and healthcare costs. In this quality improvement project, we aimed to enhance compliance with peripheral IV hub disinfection at anesthesia induction to follow the American Society of Anesthesiologists (ASA) safe medication injection guidelines. Methods This study was conducted in the main operating suite of the University of Miami's principal hospital between June and October 2023. Audits of scrubbing device utilization by the anesthesiology team and focus groups were conducted before and after two educational interventions. Educational efforts focused on increasing compliance with peripheral IV disinfection using scrubbing devices.  Results Mean use per case, inferred from the number of devices dispensed, nearly doubled from 0.44 (95% CI, 0.37 to 0.59) to 0.82 (95% CI, 0.77 to 0.88) (P < 0.0001). Implications regarding steps to further enhance compliance are discussed. Conclusions Through a simple educational program, scrubbing device utilization increased significantly from baseline.

7.
Micromachines (Basel) ; 15(6)2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38930773

RESUMO

World-to-chip interfacing remains a critical issue for microfluidic devices. Current solutions to connect tubing to rigid microfluidic chips remain expensive, laborious, or require specialized skills and precision machining. Here, we report reusable, inexpensive, and easy-to-use connectors that enable monitoring of the connection ports. Our magnetic connectors benefit from a simple one-step fabrication process and low dead volume. They sustain pressures within the high range of microfluidic applications. They represent an essential tool for rapid thermoplastic (PMMA, PC, COC) prototyping and can also be used with glass, pressure-sensitive adhesive, or thin PDMS devices.

8.
Cereb Cortex ; 34(6)2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38918077

RESUMO

It is crucial to understand how anesthetics disrupt information transmission within the whole-brain network and its hub structure to gain insight into the network-level mechanisms underlying propofol-induced sedation. However, the influence of propofol on functional integration, segregation, and community structure of whole-brain networks were still unclear. We recruited 12 healthy subjects and acquired resting-state functional magnetic resonance imaging data during 5 different propofol-induced effect-site concentrations (CEs): 0, 0.5, 1.0, 1.5, and 2.0 µg/ml. We constructed whole-brain functional networks for each subject under different conditions and identify community structures. Subsequently, we calculated the global and local topological properties of whole-brain network to investigate the alterations in functional integration and segregation with deepening propofol sedation. Additionally, we assessed the alteration of key nodes within the whole-brain community structure at each effect-site concentrations level. We found that global participation was significantly increased at high effect-site concentrations, which was mediated by bilateral postcentral gyrus. Meanwhile, connector hubs appeared and were located in posterior cingulate cortex and precentral gyrus at high effect-site concentrations. Finally, nodal participation coefficients of connector hubs were closely associated to the level of sedation. These findings provide valuable insights into the relationship between increasing propofol dosage and enhanced functional interaction within the whole-brain networks.


Assuntos
Encéfalo , Hipnóticos e Sedativos , Imageamento por Ressonância Magnética , Propofol , Humanos , Propofol/farmacologia , Propofol/administração & dosagem , Masculino , Imageamento por Ressonância Magnética/métodos , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Encéfalo/diagnóstico por imagem , Adulto , Feminino , Hipnóticos e Sedativos/farmacologia , Adulto Jovem , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Anestésicos Intravenosos/farmacologia , Mapeamento Encefálico/métodos
9.
Antiviral Res ; 227: 105907, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38772503

RESUMO

Respiratory syncytial virus (RSV) can cause pulmonary complications in infants, elderly and immunocompromised patients. While two vaccines and two prophylactic monoclonal antibodies are now available, treatment options are still needed. JNJ-7184 is a non-nucleoside inhibitor of the RSV-Large (L) polymerase, displaying potent inhibition of both RSV-A and -B strains. Resistance selection and hydrogen-deuterium exchange experiments suggest JNJ-7184 binds RSV-L in the connector domain. JNJ-7184 prevents RSV replication and transcription by inhibiting initiation or early elongation. JNJ-7184 is effective in air-liquid interface cultures and therapeutically in neonatal lambs, acting to drastically reverse the appearance of lung pathology.


Assuntos
Antivirais , Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Replicação Viral , Antivirais/farmacologia , Antivirais/química , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Infecções por Vírus Respiratório Sincicial/virologia , Animais , Humanos , Replicação Viral/efeitos dos fármacos , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Ovinos , Farmacorresistência Viral , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/metabolismo , Proteínas Virais/genética , Pulmão/virologia
10.
Cureus ; 16(4): e57561, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38707096

RESUMO

Entrapped temporal horn (ETH) is a complication following resection of ventricular trigone tumors. It is a special localized hydrocephalus. Obstruction of cerebrospinal fluid outflow following resection of ventricular trigone tumors leads to dilation of the temporal horn and the production of the local space-occupying effect. This article presents two cases of ETH following the resection of ventricular trigone tumors. Our Intraventricular shunt is an effective treatment that uses a T-connector to connect a reservoir with two catheters. We presented temporal-frontal horn shunt and trigone-front horn shunt. A patient presented with ETH shunt dependency. Our intraventricular shunt surgery achieved a good prognosis.

11.
J Virol ; 98(5): e0006824, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38661364

RESUMO

The portal protein of tailed bacteriophage plays essential roles in various aspects of capsid assembly, motor assembly, genome packaging, connector formation, and infection processes. After DNA packaging is complete, additional proteins are assembled onto the portal to form the connector complex, which is crucial as it bridges the mature head and tail. In this study, we report high-resolution cryo-electron microscopy (cryo-EM) structures of the portal vertex from bacteriophage lambda in both its prohead and mature virion states. Comparison of these structures shows that during head maturation, in addition to capsid expansion, the portal protein undergoes conformational changes to establish interactions with the connector proteins. Additionally, the independently assembled tail undergoes morphological alterations at its proximal end, facilitating its connection to the head-tail joining protein and resulting in the formation of a stable portal-connector-tail complex. The B-DNA molecule spirally glides through the tube, interacting with the nozzle blade region of the middle-ring connector protein. These insights elucidate a mechanism for portal maturation and DNA translocation within the phage lambda system. IMPORTANCE: The tailed bacteriophages possess a distinct portal vertex that consists of a ring of 12 portal proteins associated with a 5-fold capsid shell. This portal protein is crucial in multiple stages of virus assembly and infection. Our research focused on examining the structures of the portal vertex in both its preliminary prohead state and the fully mature virion state of bacteriophage lambda. By analyzing these structures, we were able to understand how the portal protein undergoes conformational changes during maturation, the mechanism by which it prevents DNA from escaping, and the process of DNA spirally gliding.


Assuntos
Bacteriófago lambda , Proteínas do Capsídeo , Capsídeo , Montagem de Vírus , Bacteriófago lambda/fisiologia , Bacteriófago lambda/genética , Capsídeo/metabolismo , Capsídeo/ultraestrutura , Proteínas do Capsídeo/metabolismo , Proteínas do Capsídeo/química , Microscopia Crioeletrônica , Empacotamento do DNA , DNA Viral/genética , DNA Viral/metabolismo , Modelos Moleculares , Conformação Proteica , Vírion/metabolismo , Vírion/ultraestrutura
12.
Materials (Basel) ; 17(5)2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38473539

RESUMO

Microscale electronics have become increasingly more powerful, requiring more efficient cooling systems to manage the higher thermal loads. To meet this need, current research has been focused on overcoming the inefficiencies present in typical thermal management systems due to low Reynolds numbers within microchannels and poor physical properties of the working fluids. For the first time, this research investigated the effects of a connector with helical geometry on the heat transfer coefficient at low Reynolds numbers. The introduction of a helical connector at the inlet of a microchannel has been experimentally tested and results have shown that this approach to flow augmentation has a great potential to increase the heat transfer capabilities of the working fluid, even at low Reynolds numbers. In general, a helical connector can act as a stabilizer or a mixer, based on the characteristics of the connector for the given conditions. When the helical connector acts as a mixer, secondary flows develop that increase the random motion of molecules and possible nanoparticles, leading to an enhancement in the heat transfer coefficient in the microchannel. Otherwise, the heat transfer coefficient decreases. It is widely known that introducing nanoparticles into the working fluids has the potential to increase the thermal conductivity of the base fluid, positively impacting the heat transfer coefficient; however, viscosity also tends to increase, reducing the random motion of molecules and ultimately reducing the heat transfer capabilities of the working fluid. Therefore, optimizing the effects of nanoparticles characteristics while reducing viscous effects is essential. In this study, deionized water and deionized water-diamond nanofluid at 0.1 wt% were tested in a two-microchannel system fitted with a helical connector in between. It was found that the helical connector can make a great heat transfer coefficient enhancement in low Reynolds numbers when characteristics of geometry are optimized for given conditions.

13.
Drug Des Devel Ther ; 18: 899-908, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38533429

RESUMO

Purpose: Co-administering multiple intravenous (IV) agents via Y-connectors is a common practice in hospitalised and fasting surgical patients. However, there is a lack of reliable data confirming the physical compatibility of some combinations including IV oxycodone, a drug that is gaining increasing popularity in the perioperative period. Concern regarding physical drug incompatibilities precludes concurrent coadministration with other common drugs through a single lumen. This can result in the cessation of infusions to allow the administration of other medications, resulting in exacerbation of acute pain. This study aims to evaluate the physical compatibility of IV oxycodone with some commonly co-administered drugs and IV fluids. Methods: Mixtures of oxycodone (1mg.mL-1) and the tested drugs and IV fluids were prepared in a ratio of 1:1. The mixtures were examined at 0 and 60 minutes from mixing and assessed using the European Conference Consensus Standards. This involved visual inspection (precipitation, turbidity, colour change, gas formation), spectrophotometry, and pH change. The tested drugs included ketamine, tramadol, clonidine, vancomycin, piperacillin/tazobactam, dexmedetomidine, cefotaxime, gentamicin, and paracetamol. In addition, the commonly used IV fluids tested included glucose 5% + sodium chloride 0.9% + 60 mmol potassium chloride, plasmalyte + dextrose 5%;plasmalyte + dextrose 5% + 55 mmol potassium chloride, plasmalyte + dextrose 5% + 55mmol potassium acetate, plasmalyte + dextrose 5% + 55mmol potassium dihydrogen phosphate, Hartmann's solution, Standard pediatric Total Parenteral Nutrition (TPN) 20/100 and TPN 25/150. Results: IV oxycodone (1 mg.mL-1) showed no visual changes; no spectrophotometric absorption variability at 350, 410, or 550nm; and no pH changes of >0.5 at 0 or 60 minutes with any of the tested drugs or fluids in the concentrations tested. Conclusion: According to European Consensus Conference Standards, IV Oxycodone at 1 mg.mL-1 is physically compatible in a ratio of 1:1 v/v with all investigated drugs and fluids tested for at least 60 minutes.


Assuntos
Oxicodona , Vancomicina , Humanos , Criança , Infusões Intravenosas , Cloreto de Potássio , Glucose
14.
Cureus ; 16(1): e51652, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38318549

RESUMO

An abutment having edentulous space on both sides is referred to as a pier abutment. The rehabilitation of a patient whose primary concern when they first came to the hospital was missing teeth is discussed in this case report. When using a pier abutment for a fixed dental prosthesis, there is a problem with fulcrum and torqueing pressures at the intermediate abutment. Forces on the pier abutment may become localized as a result of using a rigid connector. It has been suggested that non-rigid connectors be used to overcome this. Here, using a non-rigid connector as a stress breaker resulted in less stress being placed on the prosthetic assembly and abutment. This article offers a clinical case report that details the use of a non-rigid connector in a pier abutment scenario for rehabilitation.

15.
Cureus ; 16(1): e52895, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38406087

RESUMO

The attachment of a fixed partial denture (FPD) on a pier abutment may be necessary in some partially edentulous instances because of the pattern of lost teeth. Nonetheless, it has been noted that using a stiff FPD to restore two lost teeth and an intermediate pier abutment is not the best course of action. In this case, using a stiff connector concentrates the stresses on the pier abutment. In this situation, the pier abutment serves as a pivot, increasing the debonding of the fixed dental prosthesis and ultimately compromising the success of the FPD. Connectors that are not stiff can solve these issues. A nonrigid connector allows abutments to move independently and distributes shear forces to the supporting bone. Instead of the typical rigid connector, the nonrigid connector serves as a stress breaker between the retainer and the pontic.

16.
Parkinsonism Relat Disord ; 121: 106034, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38382401

RESUMO

INTRODUCTION: Connector hubs are specialized brain regions that connect multiple brain networks and therefore have the potential to affect the functions of multiple systems. This study aims to examine the involvement of connector hub regions in essential tremor. METHODS: We examined whole-brain functional connectivity alterations across multiple brain networks in 27 patients with essential tremor and 27 age- and sex-matched healthy controls to identify affected hub regions using a network metric called functional connectivity overlap ratio estimated from resting-state functional MRI. We also evaluated the relationships of affected hubs with cognitive and tremor scores in all patients and with motor function improvement scores in 15 patients who underwent postoperative follow-up evaluations after focused ultrasound thalamotomy. RESULTS: We have identified affected connector hubs in the cerebellum and thalamus. Specifically, the dentate nucleus in the cerebellum and the dorsomedial thalamus exhibited more extensive connections with the sensorimotor network in patients. Moreover, the connections of the thalamic pulvinar with the visual network were also significantly widespread in the patient group. The connections of these connector hub regions with cognitive networks were negatively associated (FDR q < 0.05) with cognitive, tremor, and motor function improvement scores. CONCLUSION: In patients with essential tremor, connector hub regions within the cerebellum and thalamus exhibited widespread functional connections with sensorimotor and visual networks, leading to alternative pathways outside the classical tremor axis. Their connections with cognitive networks also affect patients' cognitive function.


Assuntos
Tremor Essencial , Humanos , Tremor Essencial/cirurgia , Tremor , Imageamento por Ressonância Magnética , Tálamo/diagnóstico por imagem , Tálamo/cirurgia , Cerebelo/diagnóstico por imagem , Cognição
17.
Neurocrit Care ; 41(1): 109-118, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38253924

RESUMO

BACKGROUND: External ventricular drain (EVD) is used for monitoring intracranial pressure or diverting cerebrospinal fluid. However, confirmation of an infection is not immediate and requires obtaining culture results, often leading to the excessive use of antibiotics. This study aimed to compare noninfectious ventriculitis and EVD infection in terms of the risk factors, predictors, prognosis, and effectiveness of care bundle interventions. METHODS: This retrospective study was conducted at a medical center with 1,006 beds in northern Taiwan between January 2018 and July 2022. Standard EVD insertion protocols and care bundles have been implemented since 2018, along with the initiation of chlorhexidine. RESULTS: In total, 742 EVD cases were identified. Noninfectious ventriculitis typically presents with fever approximately 8 days following EVD placement, whereas EVD infection typically manifests as fever after 20 days. Aneurysmal subarachnoid hemorrhage was strongly associated with the development of noninfectious ventriculitis (adjusted odds ratio [OR] 2.6, 95% confidence interval [CI] 1.5-4.4). Alcoholism (adjusted OR 3.5, 95% CI 1.1-12.3) and arteriovenous malformation (adjusted OR 13.1, 95% CI 2.9-58.2) significantly increased the risk of EVD infection. The EVD infection rate significantly decreased from 3.6% (14 of 446) to 1.0% (3 of 219) (p = 0.03) after the implementation of chlorhexidine gluconate bathing. CONCLUSIONS: Aneurysmal subarachnoid hemorrhage or fever with neuroinflammation within 2 weeks of EVD placement is indicative of a higher likelihood of noninfectious ventriculitis. Conversely, patients with arteriovenous malformation, alcoholism, or fever with neuroinflammation occurring after more than 3 weeks of EVD placement are more likely to necessitate antibiotic treatment for EVD infection. Chlorhexidine gluconate bathing decreases EVD infection.


Assuntos
Ventriculite Cerebral , Clorexidina , Drenagem , Humanos , Ventriculite Cerebral/etiologia , Ventriculite Cerebral/prevenção & controle , Masculino , Estudos Retrospectivos , Feminino , Pessoa de Meia-Idade , Fatores de Risco , Idoso , Adulto , Taiwan , Clorexidina/análogos & derivados , Clorexidina/uso terapêutico , Hemorragia Subaracnóidea , Pacotes de Assistência ao Paciente , Alcoolismo/complicações
18.
Talanta ; 269: 125433, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38008019

RESUMO

Instrumental and environmental fluctuations are common sources of error in smartphone-based optical detection, significantly affecting the accuracy of analytical measurements. In this regard, spotting the sample and reference simultaneously and in close proximity compensates for the fluctuations. This "dual-spot" design is similar to the double-beam technique used in spectrophotometry, which reduces fluctuations in the results. The underlying hypothesis is that any instrumental and/or environmental factors influencing the color intensity in the detection zones will similarly impact the color intensity in the control zone under the same conditions. To test our design, a ratiometric microfluidic paper-based analytical device (µPAD), functionalized with a mixture of green-emissive carbon dots (CDs) and red-emissive ethidium bromide, was developed for the selective detection of ascorbic acid (AA). The green emission of the CDs is quenched by both AA and Fe3+; NaF was thus loaded onto the 3D connector as a masking agent to remove the interference effect of the Fe3+ ions. The color variations were monitored under a UV lamp, using a smartphone to capture the images, and the RGB intensities were processed using the Color Grab application. The proposed double-spot method greatly enhanced the analytical precision and accuracy of the device. A linear working range from 0 to 125 µM was obtained, and the limit of detection was 2.71 µM. The µPAD was successfully used for the detection of AA in human serum, with recoveries from 87.27 to 98.52 %.


Assuntos
Microfluídica , Pontos Quânticos , Humanos , Espectrofotometria , Ácido Ascórbico , Carbono , Corantes Fluorescentes
19.
Materials (Basel) ; 16(23)2023 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-38068087

RESUMO

Construction industrialization addresses various challenges in the traditional construction industry, enabling building structures to conserve resources and enhance energy efficiency while reducing emissions. Precast shear walls involve the factory-based production of components, followed by transportation to a construction site for assembly. The method of connecting these components is crucial for precast concrete shear wall systems. Common connection methods include lap-spliced connections, post-tensioned connections, welded connections, bolted connections, and sleeve connections. However, challenges such as construction precision and technology proficiency have limited their application. In response, a novel precast concrete shear wall system utilizing angle steel connectors has been proposed. These angle steel connectors enhance the shear resistance of horizontal joints between precast concrete shear walls and the foundation, providing provisional support for specimen positioning and installation. Presently, the seismic performance of this innovative precast shear wall system under the combined actions of cyclic horizontal loads and axial pressure or tension has been extensively investigated. In practical engineering applications, precast concrete shear wall systems are often accompanied by infill walls. However, there is limited research on the seismic performance of precast concrete shear wall systems with infill walls. To address this gap, this study designed and fabricated two novel precast concrete shear walls with different infill wall constructions. One specimen featured an infill wall composed of a single wall panel, while the other had an infill wall consisting of two panels. Pseudo-static tests were conducted on both specimens under constant axial compression. Subsequently, the seismic performance and force mechanism of the two specimens were compared with the novel precast concrete shear walls without infill walls. The test results demonstrated that the specimen with two infill wall panels exhibited superior overall performance compared to the one with a single continuous infill wall panel. Furthermore, it was observed that, during the loading process, the edge columns of specimens with infill walls provided the majority of the increased load-bearing capacity, while the infill walls made a limited contribution to the overall load-bearing capacity of the structures.

20.
Materials (Basel) ; 16(23)2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-38068131

RESUMO

In order to study the influence of steel fibers on the mechanical properties of Perfobond Leiste (PBL) shear connectors and improve the utilization of steel fibers in this structure, four push-out test specimens and eight finite element numerical models were produced to study PBL-type shear connector specimens with different steel fiber blending amounts and blending forms. The results show that in this structure, when the blending amount of steel fiber was 0.5% to 1.5%, the ultimate bearing capacity of the specimen improved linearly, and the steel fiber helped to give full play to the performance of the PBL shear connector. The steel fibers distributed in the Z-direction have a significant impact on the mechanical properties of the PBL shear connector, and the steel fibers distributed in this direction have a significant effect on increasing the ultimate bearing capacity of the specimen. Steel fibers distributed in the Y-direction can greatly improve the plasticity of concrete. In addition, the effective action area of steel fibers is the triangular area from the bottom of the PBL shear connector to the two tops of the concrete.

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