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1.
Catheter Cardiovasc Interv ; 102(7): 1311-1316, 2023 12.
Article in English | MEDLINE | ID: mdl-37890001

ABSTRACT

BACKGROUND: Vascular complications following transfemoral TAVR are associated with increased morbidity and mortality. Measures that may mitigate this risk are important. AIM: To evaluate the utility of routine, access-vessel angiography post sheath-removal in the detection and management of complications in patients undergoing transcatheter aortic valve replacement (TAVR). METHODS: This was a retrospective study of 512 consecutive patients who underwent transfemoral TAVR with routine post access-closure angiography from the radial artery. Rates of mild angiographically evident bleeding, bleeding requiring surgery/interventional-radiology, ischemia, 90-day access-site-related events, and major and minor vascular complications using Valve Academic Research Consortium 3 definitions were recorded. RESULTS: Of 512 patients, digital subtraction angiography (DSA) was undertaken via the radial artery in 467 patients (91%). In the remaining patients (9%) DSA was either not attempted, due to concerns regarding kidney disease and contrast volume, or failed due to anatomical factors (aortic tortuosity/calcification). Significant chronic kidney disease was present at baseline in 72.4% of this cohort (stages III-IV or dialysis). Ninety-four percent of cases underwent TAVR using a balloon-expandable platform. Mild iliofemoral extravasation was observed in 7.7% of the DSA cases. These cases were managed by manual compression with none requiring any vascular intervention subsequently. Valve Academic Research Consortium 3 major and minor access-site-related complications were observed in 0.4% and 12.2%, respectively. Access-site-related bleeding and ischemic events requiring interventional-radiology or vascular-surgery were observed in 0.9% and 1.7% of the DSA cases, respectively. No new renal replacement therapy was needed in any of the DSA cases. Discharge to 90-day access-related complications was 0.8%. CONCLUSIONS: Routine post access-closure angiography is feasible via the radial artery in patients undergoing transfemoral TAVR and appears safe. It facilitates early identification of complications and mitigates risk by enabling prompt action to be taken. Larger studies are needed to confirm these findings.


Subject(s)
Aortic Valve Stenosis , Transcatheter Aortic Valve Replacement , Humans , Transcatheter Aortic Valve Replacement/adverse effects , Retrospective Studies , Aortic Valve Stenosis/diagnostic imaging , Aortic Valve Stenosis/surgery , Aortic Valve Stenosis/complications , Risk Factors , Femoral Artery , Treatment Outcome , Hemorrhage/etiology , Angiography, Digital Subtraction/adverse effects , Aortic Valve/diagnostic imaging , Aortic Valve/surgery
2.
Article in English | MEDLINE | ID: mdl-36525378

ABSTRACT

OBJECTIVES: To explore the long-term clinical outcomes following intravascular lithotripsy (IVL) in calcified coronary lesions from a real-world population. BACKGROUND: IVL is a relatively new but promising modality for treating coronary calcified lesions, but there is a dearth of long-term outcome data from real-world patients. METHODS: This was a multicenter, observational study in which we enrolled all patients treated with IVL from November 2018 to February 2021 from eight centers in Europe and the United Kingdom. Procedural success, complications, and clinical outcomes (cardiac death, target vessel myocardial infarction [TVMI], target lesion revascularization [TLR], and MACE [major adverse cardiac events, the composite of cardiac death, TVMI, and TLR]) were assessed. RESULTS: In total, 273 patients with a mean age of 72 ± 9.1 years were treated with IVL. Major comorbidities included diabetes mellitus (n = 110, 40%) and chronic kidney disease (n = 45, 16%). Acute coronary syndrome accounted for 48% (n = 132) of patients, while 52% (n = 141) had stable angina. De novo lesions and in-stent restenosis accounted for 79% and 21% of cases, respectively. Intravascular imaging was used in 33% (n = 90) of patients. An upfront IVL strategy was adopted in 34% (n = 92), while the rest were bailout procedures. Adjuvant rotational atherectomy ("RotaTripsy") was required in 11% (n = 31) of cases. The procedural success was 99%. During a median follow-up of 687 days (interquartile range: 549-787), cardiac death occurred in 5% (n = 14), TVMI in 3% (n = 8), TLR in 6% (n = 16), and MACE rate was 11% (n = 30). CONCLUSION: This is the largest multicenter registry with a long-term follow-up showing the remarkably high procedural success of IVL use in calcified coronary lesions with low rates of hard endpoints and MACE.

3.
PLoS One ; 17(12): e0277532, 2022.
Article in English | MEDLINE | ID: mdl-36454869

ABSTRACT

There are currently no preventive or disease-modifying therapies for Parkinson's Disease (PD). Failures in clinical trials necessitate a re-evaluation of existing pre-clinical models in order to adopt systems that better recapitulate underlying disease mechanisms and better predict clinical outcomes. In recent years, models utilizing patient-derived induced pluripotent stem cells (iPSC) have emerged as attractive models to recapitulate disease-relevant neuropathology in vitro without exogenous overexpression of disease-related pathologic proteins. Here, we utilized iPSC derived from patients with early-onset PD and dementia phenotypes that harbored either a point mutation (A53T) or multiplication at the α-synuclein/SNCA gene locus. We generated a three-dimensional (3D) cortical neurosphere culture model to better mimic the tissue microenvironment of the brain. We extensively characterized the differentiation process using quantitative PCR, Western immunoblotting and immunofluorescence staining. Differentiated and aged neurospheres revealed alterations in fatty acid profiles and elevated total and pathogenic phospho-α-synuclein levels in both A53T and the triplication lines compared to their isogenic control lines. Furthermore, treatment of the neurospheres with a small molecule inhibitor of stearoyl CoA desaturase (SCD) attenuated the protein accumulation and aberrant fatty acid profile phenotypes. Our findings suggest that the 3D cortical neurosphere model is a useful tool to interrogate targets for PD and amenable to test small molecule therapeutics.


Subject(s)
Induced Pluripotent Stem Cells , Parkinson Disease , Humans , alpha-Synuclein/genetics , Parkinson Disease/genetics , Organoids , Fatty Acids
4.
Sensors (Basel) ; 22(19)2022 Sep 22.
Article in English | MEDLINE | ID: mdl-36236298

ABSTRACT

Internet availability and its integration with smart technologies have favored everyday objects and things and offered new areas, such as the Internet of Things (IoT). IoT refers to a concept where smart devices or things are connected and create a network. This new area has suffered from big data handling and security issues. There is a need to design a data analytics model by using new 5G technologies, architecture, and a security model. Reliable data communication in the presence of legitimate nodes is always one of the challenges in these networks. Malicious nodes are generating inaccurate information and breach the user's security. In this paper, a data analytics model and self-organizing architecture for IoT networks are proposed to understand the different layers of technologies and processes. The proposed model is designed for smart environmental monitoring systems. This paper also proposes a security model based on an authentication, detection, and prediction mechanism for IoT networks. The proposed model enhances security and protects the network from DoS and DDoS attacks. The proposed model evaluates in terms of accuracy, sensitivity, and specificity by using machine learning algorithms.


Subject(s)
Data Science , Internet of Things , Algorithms , Communication , Computer Communication Networks
6.
Neurotherapeutics ; 19(3): 1018-1036, 2022 04.
Article in English | MEDLINE | ID: mdl-35445353

ABSTRACT

Increasing evidence has shown that Parkinson's disease (PD) impairs midbrain dopaminergic, cortical and other neuronal subtypes in large part due to the build-up of lipid- and vesicle-rich α-synuclein (αSyn) cytotoxic inclusions. We previously identified stearoyl-CoA desaturase (SCD) as a potential therapeutic target for synucleinopathies. A brain-penetrant SCD inhibitor, YTX-7739, was developed and has entered Phase 1 clinical trials. Here, we report the efficacy of YTX-7739 in reversing pathological αSyn phenotypes in various in vitro and in vivo PD models. In cell-based assays, YTX-7739 decreased αSyn-mediated neuronal death, reversed the abnormal membrane interaction of amplified E46K ("3K") αSyn, and prevented pathological phenotypes in A53T and αSyn triplication patient-derived neurospheres, including dysregulated fatty acid profiles and pS129 αSyn accumulation. In 3K PD-like mice, YTX-7739 crossed the blood-brain barrier, decreased unsaturated fatty acids, and prevented progressive motor deficits. Both YTX-7739 treatment and decreasing SCD activity through deletion of one copy of the SCD1 gene (SKO) restored the physiological αSyn tetramer-to-monomer ratio, dopaminergic integrity, and neuronal survival in 3K αSyn mice. YTX-7739 efficiently reduced pS129 + and PK-resistant αSyn in both human wild-type αSyn and 3K mutant mice similar to the level of 3K-SKO. Together, these data provide further validation of SCD as a PD therapeutic target and YTX-7739 as a clinical candidate for treating human α-synucleinopathies.


Subject(s)
Parkinson Disease , alpha-Synuclein , Animals , Brain/metabolism , Humans , Mice , Neurons/metabolism , Parkinson Disease/genetics , Stearoyl-CoA Desaturase/genetics , Stearoyl-CoA Desaturase/metabolism , alpha-Synuclein/genetics , alpha-Synuclein/metabolism
7.
J Educ Health Promot ; 10: 266, 2021.
Article in English | MEDLINE | ID: mdl-34485563

ABSTRACT

BACKGROUND: The objective was to assess the prevalence and the associated demographic factors of stress, anxiety, and depression among undergraduate (UG) Indian dental students and determine whether the pattern is different in government-run institutions and those managed by private authorities. MATERIALS AND METHODS: A cross-sectional study was conducted among dental UG students from five dental colleges. Snowball sampling was used to approach 776 potential participants, resulting in a complete response from 507 students. The questionnaire consisted of demographic data; year of study; type of college; accommodation; and Depression, Anxiety, and Stress Scale (DASS)-42. Descriptive data and inferential statistics were obtained. Chi-square test was applied for categorical data to test for significance, and higher analysis was done using multiple linear regression. RESULTS: Females and males comprised 71.8% (n = 364) and 28.2% (n = 143) of the study population, respectively. The prevalence of anxiety was highest (66.86%, n = 339), followed by depression (57.39%, n = 291) and stress (43.99%, n = 223). In terms of severity also, anxiety was the most prevalent condition as more than one-fourth of the students presented with severe and very severe scores in this aspect (25.43%, n = 129) compared to depression (14.39%, n = 73) and stress (10.09%, n = 51). Regression analysis revealed age as a strong positive predictor for all the three conditions, while staying in the hostel was a positive predictor for anxiety and stress. Being female was also an independent predictor for the high prevalence of stress. CONCLUSION: Stress, anxiety, and depression are highly prevalent among Indian dental students. Clinical students and interns have a higher prevalence of stress than preclinical students. Age, being female, and staying in the hostel are positive predictors for the severity of stress. There is no significant difference between government and private colleges, regarding the prevalence of any psychological condition.

8.
Big Data ; 9(4): 253-264, 2021 08.
Article in English | MEDLINE | ID: mdl-33989047

ABSTRACT

The new and integrated area called Internet of Things (IoT) has gained popularity due to its smart, objects, services and affordability. These networks are based on data communication, augmented reality (AR), and wired and wireless infrastructures. The basic objective of these network is data communication, environment monitoring, tracking, and sensing by using smart devices and sensor nodes. The dAR is one of the attractive and advanced areas that is integrated in IoT networks in smart homes and smart industries to convert the objects into 3D to visualize information and provide interactive reality-based control. With attraction, this idea has suffered with complex and heavy processes, computation complexities, network communication degradation, and network delay. This article presents a detailed overview of these technologies and proposes a more convenient and fast data communication model by using edge computing and Fifth-Generation platforms. The article also introduces a Visualization Augmented Reality framework for IoT (VAR-IoT) networks fully integrated by communication, sensing, and actuating features with a better interface to control the objects. The proposed network model is evaluated in simulation in terms of applications response time and network delay and it observes the better performance of the proposed framework.


Subject(s)
Augmented Reality , Internet of Things , Computer Simulation
9.
J Family Med Prim Care ; 10(11): 4153-4159, 2021 Nov.
Article in English | MEDLINE | ID: mdl-35136782

ABSTRACT

BACKGROUND: Adherence to antihypertensive therapy is an important factor in determining the clinical course of hypertension. This study was planned to estimate adherence to antihypertensive therapy and its determinants among OPD patients attending two primary care hospitals in Kashmir valley. METHODS: This study employed a cross-sectional study design. All subjects who reported to OPD between October and December 2020 and had been prescribed antihypertensive medications for at least 1 year were included. Sociodemographic information was collected on a pretested schedule and adherence to medications was assessed by using the-14 item Hill-Bone HBP Compliance to High Blood Pressure Therapy Scale (HB-HBP). Mann-Whitney test and Spearman's rank correlation coefficient were used. RESULTS: A total of 406 subjects were included in the final analysis with a mean age of 58 years for women and 56 years for men. The sample comprised 54% women. More than 60% of subjects were currently married, urban area residents, and belonged to middle strata of social class. The mean score obtained in the HB-MAS (maximum score 56) was 19.26 (SD ± 4.3). Subjects aged 60 years and above, those belonging to lower socioeconomic class, and subjects prescribed three or more drugs with more than once-daily dosing regimen had higher odds of having poor adherence. CONCLUSION: There is suboptimal adherence among OPD patients at primary care level. There is a need for enhanced counselling regarding medication adherence particularly for elderly, poor, illiterate persons and those prescribed multiple medicines with more than once-daily dosing.

10.
Cell Rep ; 25(10): 2742-2754.e31, 2018 12 04.
Article in English | MEDLINE | ID: mdl-30517862

ABSTRACT

The lack of disease-modifying treatments for neurodegenerative disease stems in part from our rudimentary understanding of disease mechanisms and the paucity of targets for therapeutic intervention. Here we used an integrated discovery paradigm to identify a new therapeutic target for diseases caused by α-synuclein (α-syn), a small lipid-binding protein that misfolds and aggregates in Parkinson's disease and other disorders. Using unbiased phenotypic screening, we identified a series of compounds that were cytoprotective against α-syn-mediated toxicity by inhibiting the highly conserved enzyme stearoyl-CoA desaturase (SCD). Critically, reducing the levels of unsaturated membrane lipids by inhibiting SCD reduced α-syn toxicity in human induced pluripotent stem cell (iPSC) neuronal models. Taken together, these findings suggest that inhibition of fatty acid desaturation has potential as a therapeutic approach for the treatment of Parkinson's disease and other synucleinopathies.


Subject(s)
Stearoyl-CoA Desaturase/antagonists & inhibitors , alpha-Synuclein/toxicity , Animals , Cytoprotection/drug effects , Fatty Acids/metabolism , Humans , Lipid Metabolism/drug effects , Neurons/drug effects , Neurons/metabolism , Oxadiazoles/chemistry , Oxadiazoles/pharmacology , Protein Aggregates , Rats , Saccharomyces cerevisiae/drug effects , Stearoyl-CoA Desaturase/metabolism , Triglycerides/metabolism
11.
Neuron ; 98(6): 1141-1154.e7, 2018 06 27.
Article in English | MEDLINE | ID: mdl-29861287

ABSTRACT

The apolipoprotein E4 (APOE4) variant is the single greatest genetic risk factor for sporadic Alzheimer's disease (sAD). However, the cell-type-specific functions of APOE4 in relation to AD pathology remain understudied. Here, we utilize CRISPR/Cas9 and induced pluripotent stem cells (iPSCs) to examine APOE4 effects on human brain cell types. Transcriptional profiling identified hundreds of differentially expressed genes in each cell type, with the most affected involving synaptic function (neurons), lipid metabolism (astrocytes), and immune response (microglia-like cells). APOE4 neurons exhibited increased synapse number and elevated Aß42 secretion relative to isogenic APOE3 cells while APOE4 astrocytes displayed impaired Aß uptake and cholesterol accumulation. Notably, APOE4 microglia-like cells exhibited altered morphologies, which correlated with reduced Aß phagocytosis. Consistently, converting APOE4 to APOE3 in brain cell types from sAD iPSCs was sufficient to attenuate multiple AD-related pathologies. Our study establishes a reference for human cell-type-specific changes associated with the APOE4 variant. VIDEO ABSTRACT.


Subject(s)
Alzheimer Disease/genetics , Amyloid beta-Peptides/metabolism , Apolipoprotein E4/genetics , Induced Pluripotent Stem Cells/metabolism , Neuroglia/metabolism , Neurons/metabolism , Peptide Fragments/metabolism , tau Proteins/metabolism , Alzheimer Disease/metabolism , Apolipoprotein E3/metabolism , Apolipoprotein E4/metabolism , Astrocytes/metabolism , Brain/cytology , Brain/metabolism , CRISPR-Cas Systems , Cell Differentiation , Humans , Lipid Metabolism , Microglia/immunology , Microglia/metabolism , Organoids/metabolism , Phosphoproteins/metabolism , Synaptic Transmission , Transcriptome
13.
J Coll Physicians Surg Pak ; 27(12): 780-782, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29185408

ABSTRACT

A 33-year soldier, deployed at an altitude of 3,350 meters for two years, developed unilateral Central Retinal Vein Occlusion (CRVO) in the left eye. He had no risk factor for thrombosis and all thrombophilia screenings were negative. The patient was managed with intravitreal injections of anti-VEGF (Bevacizumab) every four weeks. He showed gradual improvement in the visual acuity over the next 3 months. Best corrected visual acuity (BCVA) after three months was 6/7.5; whereas, initially it was limited to hand movements only. This case illustrates that prolonged exposure to high altitude is a risk factor for CRVO, too. Frequent eye examination, including fundus, should be carried out among people living at such altitudes.


Subject(s)
Altitude , Angiogenesis Inhibitors/administration & dosage , Bevacizumab/administration & dosage , Retinal Vein Occlusion/drug therapy , Adult , Angiogenesis Inhibitors/therapeutic use , Bevacizumab/therapeutic use , Humans , Intravitreal Injections , Male , Military Personnel , Treatment Outcome
14.
Appl Opt ; 56(30): 8340-8347, 2017 Oct 20.
Article in English | MEDLINE | ID: mdl-29091610

ABSTRACT

In this experimental work, we address the issue of the control of two-photon absorption in a Doppler broadened medium of Rb85 atoms under the ladder level coupling 5S1/2→5P3/2→5D3/2. Here, suppression and enhancement of two-photon absorption are executed by applying an auxiliary laser beam, which is not physically propagating in the same line of the pump-probe combination. Instead, the auxiliary beam, which is in resonance with the Rb85 D2 transition, is at a finite distance from the line of propagation of the pump-probe combination. The resonant auxiliary beam produces an atomic beam in the vapor cell, and when it reaches the pump-probe path, it creates an asymmetry in the population of ground state hyperfine components. This asymmetry is responsible for controlling two-photon absorption. We present here results obtained by us along with a qualitative explanation of the physical principles behind the control mechanism.

15.
J Neurosci ; 37(41): 9917-9924, 2017 10 11.
Article in English | MEDLINE | ID: mdl-28912154

ABSTRACT

Increased p25, a proteolytic fragment of the regulatory subunit p35, is known to induce aberrant activity of cyclin-dependent kinase 5 (Cdk5), which is associated with neurodegenerative disorders, including Alzheimer's disease. Previously, we showed that replacing endogenous p35 with the noncleavable mutant p35 (Δp35) attenuated amyloidosis and improved cognitive function in a familial Alzheimer's disease mouse model. Here, to address the role of p25/Cdk5 in tauopathy, we generated double-transgenic mice by crossing mice overexpressing mutant human tau (P301S) with Δp35KI mice. We observed significant reduction of phosphorylated tau and its seeding activity in the brain of double transgenic mice compared with the P301S mice. Furthermore, synaptic loss and impaired LTP at hippocampal CA3 region of P301S mice were attenuated by blocking p25 generation. To further validate the role of p25/Cdk5 in tauopathy, we used frontotemporal dementia patient-derived induced pluripotent stem cells (iPSCs) carrying the Tau P301L mutation and generated P301L:Δp35KI isogenic iPSC lines using CRISPR/Cas9 genome editing. We created cerebral organoids from the isogenic iPSCs and found that blockade of p25 generation reduced levels of phosphorylated tau and increased expression of synaptophysin. Together, these data demonstrate a crucial role for p25/Cdk5 in mediating tau-associated pathology and suggest that inhibition of this kinase can remedy neurodegenerative processes in the presence of pathogenic tau mutation.SIGNIFICANCE STATEMENT Accumulation of p25 results in aberrant Cdk5 activation and induction of numerous pathological phenotypes, such as neuroinflammation, synaptic loss, Aß accumulation, and tau hyperphosphorylation. However, it was not clear whether p25/Cdk5 activity is necessary for the progression of these pathological changes. We recently developed the Δp35KI transgenic mouse that is deficient in p25 generation and Cdk5 hyperactivation. In this study, we used this mouse model to elucidate the role of p25/Cdk5 in FTD mutant tau-mediated pathology. We also used a frontotemporal dementia patient-derived induced pluripotent stem cell carrying the Tau P301L mutation and generated isogenic lines in which p35 is replaced with noncleavable mutant Δp35. Our data suggest that p25/Cdk5 plays an important role in tauopathy in both mouse and human model systems.


Subject(s)
Cyclin-Dependent Kinase 5/genetics , Frontotemporal Dementia/genetics , Phosphotransferases/genetics , Pluripotent Stem Cells , Tauopathies/genetics , Animals , CA3 Region, Hippocampal/pathology , CA3 Region, Hippocampal/physiopathology , Cyclin-Dependent Kinase 5/antagonists & inhibitors , Frontotemporal Dementia/prevention & control , Humans , Long-Term Potentiation/genetics , Mice , Mice, Transgenic , Mossy Fibers, Hippocampal/pathology , Phosphorylation , Phosphotransferases/antagonists & inhibitors , Stem Cell Transplantation , Synapses/pathology , Synaptophysin/genetics , Tauopathies/prevention & control
16.
ACS Biomater Sci Eng ; 3(3): 360-369, 2017 Mar 13.
Article in English | MEDLINE | ID: mdl-33465933

ABSTRACT

Microneedles represent an exciting departure from the existing parenteral injection paradigm for drug delivery, particularly for the administration of vaccines. While the benefit of delivering vaccine antigens to immunocompetent tissue in the skin has been established, there have been varying degrees of success using microneedles to do so. Here, we investigate the use of silk fibroin protein to produce microneedles and evaluate their ability to deliver vaccines against influenza, Clostridium difficile, and Shigella. Fibroin protein from the silkworm Bombyx mori possesses suitable properties for use in a microneedle system, including all-aqueous processing, mechanical strength in dried formats, biocompatibility, and the ability to temperature stabilize biomacromolecules. As such, this biomaterial combines the processing and biocompatibility advantages of a dissolving microneedle system with the product stability and mechanical strength of coated insoluble microneedles. Through successful vaccination of mice against three separate antigens, we establish that silk fibroin is well-suited for use as a solid-coated microneedle delivery system and offers long-term potential similar to that of the leading microneedle biomaterials.

17.
PLoS One ; 11(9): e0161969, 2016.
Article in English | MEDLINE | ID: mdl-27622770

ABSTRACT

The dismal success rate of clinical trials for Alzheimer's disease (AD) motivates us to develop model systems of AD pathology that have higher predictive validity. The advent of induced pluripotent stem cells (iPSCs) allows us to model pathology and study disease mechanisms directly in human neural cells from healthy individual as well as AD patients. However, two-dimensional culture systems do not recapitulate the complexity of neural tissue, and phenotypes such as extracellular protein aggregation are difficult to observe. We report brain organoids that use pluripotent stem cells derived from AD patients and recapitulate AD-like pathologies such as amyloid aggregation, hyperphosphorylated tau protein, and endosome abnormalities. These pathologies are observed in an age-dependent manner in organoids derived from multiple familial AD (fAD) patients harboring amyloid precursor protein (APP) duplication or presenilin1 (PSEN1) mutation, compared to controls. The incidence of AD pathology was consistent amongst several fAD lines, which carried different mutations. Although these are complex assemblies of neural tissue, they are also highly amenable to experimental manipulation. We find that treatment of patient-derived organoids with ß- and γ-secretase inhibitors significantly reduces amyloid and tau pathology. Moreover, these results show the potential of this model system to greatly increase the translatability of pre-clinical drug discovery in AD.


Subject(s)
Alzheimer Disease/pathology , Induced Pluripotent Stem Cells/physiology , Amyloid beta-Peptides/metabolism , Brain/cytology , Brain/pathology , Cell Line , Endosomes/pathology , Humans , Organoids/cytology , Organoids/pathology , Phenotype , Phosphorylation , Tissue Scaffolds , tau Proteins/metabolism
18.
Sci Rep ; 6: 24539, 2016 Apr 15.
Article in English | MEDLINE | ID: mdl-27080420

ABSTRACT

With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (µc-Si) layer is only ~1/6 of conventional µc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device. In particular, the nanoshells core radius and metal thickness, the periodicity, the incident angle of the solar radiation and its wavelength are varied in the widest meaningful ranges. We further explain the reason for the absorption enhancement by calculating the electric field distribution associated to resonances of the device. We argue that both Fabry-Pérot-like and localized plasmon modes play an important role in this regard.

19.
J Orthop Res ; 34(4): 581-90, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26419698

ABSTRACT

Bioelectrical regulation of bone fracture healing is important for many cellular events such as proliferation, migration, and differentiation. The aim of this study was to investigate the osteogenic differentiation potential of human mesenchymal stem cells (hMSCs) cultivated on silk scaffolds in response to different modes of electrostimulation (e.g., exogeneous and/or endogeneous). Endogeneous electrophysiology was altered through the use of monensin (10 nM) and glibenclamide (10 µM), along with external electrostimulation (60 kHz; 100-500 mV). Monensin enhanced the expression of early osteogenic markers such as alkaline phosphatase (ALP) and runt-related transcription factor 2 (RUNX-2). When exogeneous electrostimulation was combined with glibenclamide, more mature osteogenic marker upregulation based on bone sialoprotein expression (BSP) and mineralization was found. These results suggest the potential to exploit both exogeneous and endogeneous biophysical control of cell functions towards tissue-specific goals.


Subject(s)
Cell Culture Techniques , Cell Differentiation , Mesenchymal Stem Cells/physiology , Osteogenesis , Tissue Scaffolds , Alkaline Phosphatase/metabolism , Animals , Bombyx , Calcium/metabolism , Cell Proliferation , Electric Stimulation , Humans , Mesenchymal Stem Cells/cytology , Silk
20.
Opt Express ; 23(19): A1220-35, 2015 Sep 21.
Article in English | MEDLINE | ID: mdl-26406751

ABSTRACT

A series of photonic crystal structures are optimized for a photon enhanced thermionic emitter. With realistic parameter values to describe a p-type GaAs device we find an efficiency above 10%. The light-trapping structures increases the performance by 2% over an optimal bilayer anti-reflective coating. We find a device efficiency very close to the case of a Lambertian absorber, but below its maximum performance. To prevent an efficiency below 10% the vacuum gap must be dimensioned according to the concentration factor of the solar irradiance.

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