Cefixime loaded bare and functionalized halloysite nanocarriers and their biomedical applications.

Effective drug delivery for is the foremost requirement for the complete recovery of the disease. Nanomedicine and nanoengineering has provided so many spaces and ideas for the drug delivery design, whether controlled, targeted, or sustained. Different types of nanocarriers or nanoparticles are aggressively designed for the drug delivery applications. Clay minerals are identified as a one of the potential nanocarrier for the drug delivery. Owing to their biocompatibility and very low cytotoxicity, clay minerals showing effective therapeutic applications. In the present investigation, clay mineral, i.e., Halloysite nano tubes are utilized as a nanocarrier for the delivery of antibiotic cefixime (CFX), a third-generation cephalosporin. The HNT was first functionalized with the sulfuric acid and then further treated with the 3-(aminopropyl)triethoxysilane (APTES). The drug is loaded on three different classifications of HNTs, i.e., Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT and their comparative analysis is established. Different characterization techniques such as X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), Transmission electron microscopy TEM), Brunauer-Emmett-Teller (BET), adsorption studies, and Thermogravimetric analysis (TGA) were performed to evaluate their chemical, structural, morphological, and thermal properties. TGA confirmed the encapsulation efficiency of Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT as 42.65, 52.19, and 53.43%, respectively. Disk diffusion and MTT assay confirmed that the drug loaded HNTs have potential antibacterial activities and less cytotoxicity. The adsorption capacity of CFX with different HNTs are evaluated and Different adsorption and kinetic models have been discussed. Drug release studies shows that APTES-CFX-HNT showing sustained release of cefixime as compared to Bare-CFX-HNT and Acid-CFX-HNT.

Augmentin loaded functionalized halloysite nanotubes: A sustainable emerging nanocarriers for biomedical applications.

Clay minerals such as Halloysite nanotubes (HNTs), abundantly available green nanomaterial, exhibit a significant advantage in biomedical applications such as drug delivery, antibacterial and antimicrobials, tissue engineering or regeneration, etc. Because of the mesoporous structure and high absorbability, HNTs exhibit great potential as a nanocarrier in drug delivery applications. The sulfuric acid treatment enhances the surface area of the HNTs and thereby improves their drug-loading capacity by enlarging their lumen space/inner diameter. In the present investigation, based on the literature that supports the efficacy of drug loading after acid treatment, a dual treatment was performed to functionalize the HNTs surface. First, the HNTs were etched and functionalized using sulfuric acid. The acid-functionalized HNTs underwent another treatment using (3-aminopropyl) triethoxysilane (APTES) to better interact the drug molecules with the HNTs surfaces for efficient drug loading. Augmentin, a potential drug molecule of the penicillin group, was used for HNTs loading, and their antibacterial properties, cytotoxicity, and cumulative drug release (%) were evaluated. Different characterization techniques, such as X-ray diffractometer (XRD) and Fourier Transform Infra-Red (FT-IR), confirm the loading of Augmentin to the APTES@Acid HNTs. TEM images confirm the effective loading of the drug molecule with the HNTs. The drug encapsulation efficiency shows 40.89%, as confirmed by the Thermogravimetric Analysis (TGA). Also, the Augmentin-loaded APTES@Acid HNTs exhibited good antibacterial properties against E. coli and S. aureus and low cytotoxicity, as confirmed by the MTT assay. The drug release studies confirmed the sustainable release of Augmentin from the APTES@Acid HNTs. Hence, the treated HNTs can be considered as a potential nanocarrier for effectively delivering Augmentin and promoting enhanced therapeutic benefits.

Prenatal Risk Factors and Outcomes of Pseudoamniotic Band Sequence following Fetoscopic Laser Surgery: Systematic Review, and Meta-Analysis.

BACKGROUND: Pseudoamniotic band sequence (PABS) is a rare iatrogenic consequence of invasive fetal interventions, most commonly fetoscopic laser surgery (FLS) in monochorionic multiple pregnancies complicated by twin-to-twin transfusion syndrome (TTTS). OBJECTIVES: The aim of this study was to investigate prenatal risk factors and perinatal outcomes for pregnancies involving PABS after FLS for TTTS and compare outcomes between those undergoing fetoscopic band release versus not. METHOD: We conducted a systematic search of PubMed, Scopus, and Web of Science on studies reporting PABS following FLS for TTTS. A meta-analysis of pooled proportions was conducted. RESULTS: There were 16 studies covering 47 pregnancies complicated by PABS following FLS, mostly case series and case reports. The incidence of PABS was 2%, with the recipient twin affected in 94% of the cases. Pregnancies complicated by PABS were associated with inter-twin septostomy in 32% and chorioamniotic separation (CAS) in 90%. The mean gestational age (GA) at FLS and delivery were 17.7 and 30.9 weeks, respectively. Preterm premature rupture of membranes (PPROM) happened in 62% of pregnancies. The risk of preterm birth (PTB) <34 weeks, <32 weeks, and <28 weeks were 94%, 67%, and 31%, respectively. There were 41% fetal demises and 64% live births among the affected fetuses. Results of fetoscopic band release versus not were comparable, including GA at delivery, PPROM, and PTB at 32 weeks. It was noted that the likelihood of PTB by 28 weeks (67% vs. 23%) and fetal death (50% vs. 39%) were higher in the band release group. It was similar between groups in terms of postnatal amputation. CONCLUSIONS: PABS causes amputations or fetal death in more than one-third of cases. Pregnancies with an inter-twin septostomy, CAS, advanced TTTS staging, and early GA are more likely to experience PABS. In addition, more than a third of FLS-treated TTTS resulted in PTB and PPROM. PABS cases with prenatal band release showed higher rates of PTB and fetal death, but the data were from small, heterogeneous studies.

In Silico, In Vitro and Ex Vivo Evaluation of the Antihyperglycaemic, Antioxidant and Cytotoxic Properties of Coccinia grandis L. Leaf Extract.

Research background: Coccinia grandis L. is traditionally used for the treatment of diabetes mellitus. Since the scientific evidence and mechanism of action have not yet been extensively investigated, this study aims to evaluate the antidiabetic and cytotoxic effects together with the optimisation and development of a scale-up process design for higher yields of bioactive phytocompounds from C. grandis. Experimental approach: The in silico study was conducted to predict the binding affinity of phytocompounds of C. grandis for α-amylase and α-glucosidase enzymes involved in the pathophysiology of diabetes with pharmacokinetic assessment. Response surface methodology was used to determine the optimum total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC) and antioxidant activities (DPPH and FRAP) in 17 different experimental runs in which the parameters of microwave-assisted extraction such as temperature (50-70 °C), power (400-1000 W) and time (15-45 min) were varied. The phytocompounds were purified and identified using column chromatography, thin-layer chromatography (TLC), UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and liquid chromatography-mass spectrometry (LC-MS). The in vitro antidiabetic activity was determined by α-amylase and α-glucosidase enzymatic inhibitory assays, while cytotoxic investigations were done by measuring haemolytic activity, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and chorioallantoic membrane (CAM) assays. Results and conclusions: The reported major bioactive compounds have shown an excellent binding affinity for α-amylase and α-glucosidase enzymes in the range of -14.28 to -36.12 kJ/mol with good pharmacokinetic properties and toxicities ranging from low to medium. The bioactive constituents such as total phenols, total flavonoids, total tannins and antioxidant activities such as DPPH and FRAP were found to be high and dependent on the optimised microwave-assisted extraction parameters such as temperature, time and power: 55 °C, 45 min and 763 W, respectively. Sixteen compounds were identified by FTIR and LC-MS spectra in the plant sample after preliminary identification, purification and TLC. The percentage of enzyme inhibition depended on the concentration of the extract (7.8-125.0 µg/mL) and was higher than that of acarbose. The haemolytic activity was in accordance with ISO standards and low toxicity was observed in the MTT and CAM assays in the range of 7.8-125.0 µg/mL, suggesting its potential use as an antidiabetic drug and for functional food development. Novelty and scientific contribution: The results of the study open up new opportunities for researchers, scientists and entrepreneurs in the food and pharmaceutical sectors to develop antidiabetic foods and medicines that help diabetics to better control their condition and maintain overall health.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review.

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

High performance filtration membranes from electrospun poly (3-hydroxybutyrate)-based fiber membranes for fine particulate protection.

PM2.5 (particulate matter with a size of <2.5 µm) pollution has become a critical issue owing to its adverse health effects, including bronchitis, pneumonopathy, and cardiovascular diseases. Globally, around 8.9 million premature casualties related to exposure to PM2.5 were reported. Face masks are the only option that may restrict exposure to PM2.5. In this study, a PM2.5 dust filter was developed via the electrospinning technique using the poly (3-hydroxybutyrate) (PHB) biopolymer. Smooth and continuous fibers without beads were formed. The PHB membrane was further characterized, and the effects of the polymer solution concentration, applied voltage, and needle-to-collector distance were analyzed via the design of experiments technique, with three factors and three levels. The concentration of the polymer solution had the most significant effect on the fiber size and the porosity. The fiber diameter increased with increasing concentration, but decreases the porosity. The sample with a fiber diameter of ∼600 nm exhibited a higher PM2.5 filtration efficiency than the samples with a diameter of 900 nm, according to an ASTM F2299-based test. The PHB fiber mats fabricated at a concentration of 10%w/v, applied voltage of 15 kV, and needle tip-to-collector distance of 20 cm exhibited a high filtration efficiency of 95% and a pressure drop of <5 mmH2O/cm2. The tensile strength of the developed membranes ranged from 2.4 to 5.01 MPa, higher than those of the mask filters available in the market. Therefore, the prepared electrospun PHB fiber mats have great potential for the manufacture of PM2.5 filtration membranes.

BAALC gene expression tells a serious patient outcome tale in NPM1-wild type/FLT3-ITD negative cytogenetically normal-acute myeloid leukemia in adults.

Acute myeloid leukemia with normal cytogenetics (CN-AML) is the largest group of AML patients which is associated with a variegated patient outcome. Multiple molecular markers have been used to risk-stratify these patients. Estimation of expression of BAALC gene (Brain and Acute Leukemia, Cytoplasmic) mRNA level is one of the predictive markers which has been identified in multiple studies. In this study, we examined the clinical and prognostic value of BAALC gene expression in 149 adult CN-AML patients. We also utilized multi-omics databases to ascertain the association of BAALC gene expression with comprehensive molecular and clinicopathologic features in AML. BAALC overexpression was associated with CD34 positivity on leukemic blasts (p = 0.0026) and the absence of NPM1 gene mutation (p < 0.0001), presence of RUNX1 gene mutation (p < 0.001) and poor patient outcomes, particularly in NPM1-wild type/FLT3-ITD negative adult CN-AML patients. Additionally, BAALC expression was associated with the alteration of methylation of its promoter. Further, pathway analysis revealed that BAALC expression is correlated with MYC targets and Ras signalling. We conclude that high BAALC expression associates with poor patient outcome in NPM1-wild type/FLT3-ITD negative adult CN-AML patients.

Anisotropic Surface Broadening and Core Depletion during the Evolution of a Strong-Field Induced Nanoplasma.

Strong-field ionization of nanoscale clusters provides excellent opportunities to study the complex correlated electronic and nuclear dynamics of near-solid density plasmas. Yet, monitoring ultrafast, nanoscopic dynamics in real-time is challenging, which often complicates a direct comparison between theory and experiment. Here, near-infrared laser-induced plasma dynamics in ∼600 nm diameter helium droplets are studied by femtosecond time-resolved x-ray coherent diffractive imaging. An anisotropic, ∼20 nm wide surface region, defined as the range where the density lies between 10% and 90% of the core value, is established within ∼100 fs, in qualitative agreement with theoretical predictions. At longer timescales, however, the width of this region remains largely constant while the radius of the dense plasma core shrinks at average rates of ≈71 nm/ps along and ≈33 nm/ps perpendicular to the laser polarization. These dynamics are not captured by previous plasma expansion models. The observations are phenomenologically described within a numerical simulation; details of the underlying physics, however, remain to be explored.

Prognostic utility of key copy number alterations in T cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is a genetically heterogeneous disease, characterized by an abnormal transformation of T cells into highly proliferative leukemic lymphoblasts. Identification of common genetic alterations has provided promising opportunities for better risk stratification in T-ALL. Current treatment in T-ALL still poses the major challenge of integrating the knowledge of molecular alterations in the clinical setting. We utilized the Multiplex Ligation Dependent Probe Amplification (MLPA) method to determine the frequency of common copy number alterations (CNAs) in 128 newly diagnosed T-ALL patients. We also studied the association of these CNAs with patient's clinical characteristics and survival. The highest frequency of deletion was observed in CDKN2A (59.38%), followed by CDKN2B (46.88%), LMO1 (37.5%), and MTAP (28.12%). PTPN2 (22.66%), PHF6 (14.06%), and MYB (14.06%) had the highest number of duplication events. A total of 89.06% patients exhibited CNAs. STIL::TAL1, NUP214::ABL1, and LMO2::RAG2 fusions were observed in 5.47%, 3.12%, and 0.78% of patients, respectively. CDKN2A, CDKN2B, and PTPN2 gene deletions were mainly observed in pediatric patients, while CNAs of NF1 and SUZ12 were observed more frequently in adults. In pediatric patients, alterations in CDKN2B, CASP8AP2, and AHI1 were associated with poor prognosis, while SUZ12 and NF1 CNAs were associated with favorable prognosis. In adult patients, ABL1 CNA emerged as an independent indicator of poor prognosis. The observed molecular heterogeneity in T-ALL may provide the basis for variations observed in clinical response in T-ALL and MLPA based CNA detection may help in risk stratification of these patients.

Isolation, modification, and characterization of rice starch with emphasis on functional properties and industrial application: a review.

Starch is one of the organic compounds after cellulose found most abundantly in nature. Starch significantly varies in their different properties like physical, chemical, thermal, morphological and functional. Therefore, starch is modified to increase the beneficial characteristics and remove the shortcomings issues of native starches. The modification methods can change the extremely flexible polymer of starch with their modified physical and chemical properties. These altered structural attributes are of great technological values which have a wide industrial potential in food and non-food. Among them, the production of novel starches is mainly one that evolves with new value-added and functional properties is on high industrial demands. This paper provides an overview of the rice starch components and their effect on the technological and physicochemical properties of obtained starch. Besides, the tuned techno-functional properties of the modified starches through chemical modification means are highlighted.HighlightsNative and modified starches varies largely in physicochemical and functional traits.Modified physical and chemical properties of starch can change the extremely flexible polymer of starch.Techno-functional properties of the modified starches through chemical modification means are highlighted.Dual modification improves the starch functionality and increases the industrial applications.Production of novel starches is on high industrial demands because it mainly evolves with new value added and functional properties.

Trends and Technological Advancements in the Possible Food Applications of Spirulina and Their Health Benefits: A Review.

Spirulina is a kind of blue-green algae (BGA) that is multicellular, filamentous, and prokaryotic. It is also known as a cyanobacterium. It is classified within the phylum known as blue-green algae. Despite the fact that it includes a high concentration of nutrients, such as proteins, vitamins, minerals, and fatty acids-in particular, the necessary omega-3 fatty acids and omega-6 fatty acids-the percentage of total fat and cholesterol that can be found in these algae is substantially lower when compared to other food sources. This is the case even if the percentage of total fat that can be found in these algae is also significantly lower. In addition to this, spirulina has a high concentration of bioactive compounds, such as phenols, phycocyanin pigment, and polysaccharides, which all take part in a number of biological activities, such as antioxidant and anti-inflammatory activity. As a result of this, spirulina has found its way into the formulation of a great number of medicinal foods, functional foods, and nutritional supplements. Therefore, this article makes an effort to shed light on spirulina, its nutritional value as a result of its chemical composition, and its applications to some food product formulations, such as dairy products, snacks, cookies, and pasta, that are necessary at an industrial level in the food industry all over the world. In addition, this article supports the idea of incorporating it into the food sector, both from a nutritional and health perspective, as it offers numerous advantages.

Hydrophobicity Directed Chiral Self-Assembly and Aggregation-Induced Emission: Diacetylene-Cored Pseudopeptide Chiral Dopants.

Here we delineate simple and tunable hydrophobically driven chiral functional assemblies of diacetylene cored pseudopeptides. These amino acid appended, rigid core dialkynes constitute promising chiral supramolecular building blocks for materials properties engineering. The chiral appended amino acid elements allow for simple tuning of solubility and interaction properties as well as governing chirality, while the central dialkyne core can impart hydrophobically driven assembly and Aggregation Induced Emission (AIE) properties. The self-assembly of these rod-like dialkynes can be regulated by tuning the solvent environment, with for example self-assembly into vesicles in acetonitrile and into helical organization with AIE in a H2 O/DMSO mixture. Of additional high interest, these supramolecular materials, themselves devoid of liquid crystal (LC) properties, can induce chirality into non-chiral LC matrices with high helical twisting power.

Prognostic significance of CD45 antigen expression in pediatric acute lymphoblastic leukemia.

OBJECTIVES: The treatment of pediatric acute lymphoblastic leukemias (ALL) has seen remarkable advances recently. However, relapse occurs in approximately 20% of cases which necessitates identifying additional high risk parameters for treatment intensification. The aim of this study is to assess the prognostic significance of CD45 antigen expression in pediatric ALL. METHODS: We studied 363 pediatric patients with B cell precursor-ALL (BCP-ALL) (n = 313) and T-ALL (n = 50). The ratio of median fluorescence intensity of CD45 expressed in leukemic blasts and normal lymphocytes was calculated. The 75th percentile was taken as cut-off to categorise patients into CD45 high and CD45 low groups. RESULTS: The 75th percentile was 0.141 in BCP-ALL and 0.548 in T-ALL. In BCP-ALL, there was a statistically significant association of age (≥10 years) (p = 0.027) and National Cancer Institute high risk group (p = 0.001) with high CD45 expression but not in T-ALL. Worse event-free survival (EFS) was seen with high CD45 expression in BCP-ALL (42.17% versus 60.83%, p = 0.0053). In T-ALL, there was no association between CD45 expression and EFS (CD45 high 40.40% versus low 67.35%, p = 0.414). The overall survival (OS) was 70% versus 60% (p = 0.38) in BCP-ALL and the OS was 82% versus 68% (p = 0.16) in T-ALL for CD45 low versus CD45 high groups, respectively. CONCLUSION: We conclude that high CD45 surface expression is associated with worse EFS in pediatric BCP-ALL.

Bowel ischemia in COVID-19: A systematic review.

BACKGROUND: Gastrointestinal complications of COVID-19 have been reported over the last year. One such manifestation is bowel ischaemia. This study thus aims to provide a more holistic review of our current understanding of COVID-19-induced bowel ischaemia. METHOD AND RESULTS: A meticulous search was performed using different keywords in PubMed and Google Scholar. Fifty-two articles were included in our study after applying inclusion and exclusion criteria and performing the qualitative assessment of the studies. A total of 25 702 patients were included in our study after the completion of the qualitative assessment. DISCUSSION: The common symptoms of GIT in COVID-19 patients are as diarrhoea, vomiting, nausea and abdominal pain. The mechanism of bowel ischaemia is associated with the formation of emboli which is related to COVID-19's high affinity for angiotensin-converting enzyme-2 on enterocytes, affecting the superior mesenteric vessels. Clinically, patients present with abdominal pain and vomiting. CT angiography of the abdomen and pelvis showed acute intestinal ischaemia (mesenteric). Management is usually initiated with gastric decompression, fluid resuscitation, and haemodynamic support. Surgical intervention is also sought. CONCLUSION: Intestinal ischaemia presenting in patients with COVID-19 has to be considered when symptoms of severe abdominal pain are present. More research and guidelines are required to triage patients with COVID-19 to suspect intestinal ischaemia and to help in diagnosis and management.

Mexican Oregano (Lippia graveolens Kunth) as Source of Bioactive Compounds: A Review.

Lippia graveolens is a traditional crop and a rich source of bioactive compounds with various properties (e.g., antioxidant, anti-inflammatory, antifungal, UV defense, anti-glycemic, and cytotoxicity) that is primarily cultivated for essential oil recovery. The isolated bioactive compounds could be useful as additives in the functional food, nutraceuticals, cosmetics, and pharmaceutical industries. Carvacrol, thymol, ß-caryophyllene, and p-cymene are terpene compounds contained in oregano essential oil (OEO); flavonoids such as quercetin O-hexoside, pinocembrin, and galangin are flavonoids found in oregano extracts. Furthermore, thermoresistant compounds that remain in the plant matrix following a thermal process can be priced in terms of the circular economy. By using better and more selective extraction conditions, the bioactive compounds present in Mexican oregano can be studied as potential inhibitors of COVID-19. Also, research on extraction technologies should continue to ensure a higher quality of bioactive compounds while preventing an undesired chemical shift (e.g., hydrolysis). The oregano fractions can be used in the food, health, and agricultural industries.

Angular Momentum in Rotating Superfluid Droplets.

The angular momentum of rotating superfluid droplets originates from quantized vortices and capillary waves, the interplay between which remains to be uncovered. Here, the rotation of isolated submicrometer superfluid ^{4}He droplets is studied by ultrafast x-ray diffraction using a free electron laser. The diffraction patterns provide simultaneous access to the morphology of the droplets and the vortex arrays they host. In capsule-shaped droplets, vortices form a distorted triangular lattice, whereas they arrange along elliptical contours in ellipsoidal droplets. The combined action of vortices and capillary waves results in droplet shapes close to those of classical droplets rotating with the same angular velocity. The findings are corroborated by density functional theory calculations describing the velocity fields and shape deformations of a rotating superfluid cylinder.

Infrared Spectroscopy of Water and Zundel Cations in Helium Nanodroplets.

Here, we show that electron impact ionization of helium (He) droplets doped with water molecules and clusters yield water and Zundel cations embedded in the droplets consisting of a few thousand helium atoms. Infrared spectra in the OH-stretching range were obtained using the release of the cations from the droplets upon laser excitation. The spectra in He droplets appear to have about a factor of 10 narrower bands and similar matrix shifts as compared to those obtained via tagging with He and Ar atoms. The results confirm the calculated structure of the free Zundel ion, where the proton is equidistant from the two water units. The effect of the He environment on the spectra of ions is discussed. The signal shows nonlinear laser pulse energy dependence consistent with the evaporation of the entire droplet upon multiple absorptions of infrared photons. This conclusion is supported by the model calculations of the efficiency of the cations' release vs laser flux.

Role of strain imaging for assessment of myocardial viability in symptomatic myocardial infarction with single vessel disease: An observational study.

PURPOSE: To study and evaluate the predictive value of strain imaging parameters in patients undergoing viability assessment postmyocardial infarction (MI) in comparison with Dobutamine stress echocardiography (DSE) alone. METHODS: This was a prospective observational study (October, 2016-March, 2018), which recruited 100 symptomatic patients with MI, and angiographically proven single vessel disease, LV dysfunction with severe hypokinesia/akinesia on 2D echocardiography and viability proven by baseline DSE. Patients undergoing primary PCI were excluded. Patients were recruited in two groups: DSE alone (first group) and strain imaging with DSE (second group). Revascularization was done in all patients. Patients were assessed at 3 months for functional recovery by 2D echocardiography. RESULTS: On 3 month follow-up after revascularization, 37 patients (74%) in first group and 33 patients (66.67%) in second group had functional recovery. Dobutamine-stimulated strain parameters such as circumferential strain (CS; P = .005), radial velocity (RV; P < .001), longitudinal strain (LS; P < .001), and longitudinal strain rate (LSR; P < .001) were found to be a significant predictor of viability. The greatest area under the curve (AUC) for the ROC curves was obtained for low dose dobutamine RV (AUC = 0.92), low dose dobutamine LS (AUC = 0.94), and low dose dobutamine LSR (AUC = 0.88). Positive predictive value of the combination of low dose DSE with strain parameters (RV-97.2%, LS-97.4%, and LSR-87.5%) for myocardial viability was significantly higher than low dose DSE positive/low dose strain parameters negative patients as well as low dose DSE group alone. CONCLUSION: Evaluation of strain parameters with low dose DSE is clinically feasible for the detection of myocardial viability and adds incremental value to the subjective and semiquantitative wall-motion scoring. LS at low dose DSE with WMSI was found to have the highest positive predictive value.

Electro-analytical investigation of potential induced degradation in mc-silicon solar cells: case of sodium ion induced inductive loop.

Potential induced degradation of the shunt type (PID-s) in multi-crystalline silicon (mc-Si) solar cells is becoming critical for performance reduction of solar panels in large scale photovoltaic (PV) power plants. In this article PID-s has been investigated by applying high voltage stress on mc-Si solar cells for their degradation and recovery and results have been explained on the basis of DC and AC characterization. The efficiency decreases drastically from 15.7% to 2.9% due to a high voltage stress of -800 V at 85 °C for 48 hours, which is attributed to a reduction in shunt resistance and an increase in depletion and diffusion capacitances. The reduction in electrical performance due to PID-s has been further explained by morphological, structural and elemental analysis. Observed negative capacitance behaviour in impedance spectra of mc-Si solar cells after PID-s has been attributed to structural deformation caused by potential induced migration of sodium ions (Na+) into mc-Si. The structural deformation induced by potential induced migration of Na+ ions has been confirmed by using non-destructive and lattice strain sensitive micro-Raman spectroscopy. The obtained experimental results have been correlated with existing theoretical understanding of p-n junction solar cells to explain the consequences of PID-s.

Formation of He4+ via electron impact of helium droplets.

Electron impact ionization of superfluid helium droplets containing several thousand atoms produces a broad distribution of Hen+ ions that peaks at n = 2 and decreases monotonically toward larger n. In larger droplets (say 105 or more atoms), however, the He4+ signal intensity is anomalously large. We have studied the mechanism for the formation of He4+ ions in large helium droplets by varying the duration of the electron impact excitation pulse. Droplets of different average sizes were generated using the expansion of helium at 20 bars and 9-20 K through a pulsed valve nozzle. The resulting ions were analyzed by time-of-flight mass spectroscopy (TOFMS) and quadrupole mass spectroscopy (QMS). The intensity distributions obtained with the TOFMS technique initially showed much smaller He4+ signals than those obtained using QMS. However, we discovered that the intensity anomaly is associated with the duration of the electron bombardment pulse in the TOFMS instrument. Measurements with different electron bombardment pulse durations enabled us to discern a characteristic time of ∼10 µs for enhanced He4+ production in large droplets under our experimental conditions. A qualitative model is presented in which metastables interact on droplet surfaces, yielding two He2+ cores that share a Rydberg electron while minimizing repulsion between the cores. This is the He4+(4A2) state suggested by Knowles and Murrell.