Ionic liquids: environmentally sustainable materials for energy conversion and storage applications

Ionic liquids (ILs), often known as green designer solvents, have demonstrated immense application potential in numerous scientific and technological domains. ILs possess high boiling point and low volatility that make them suitable environmentally benign candidates for many potential applications. The more important aspect associated with ILs is that their physicochemical properties can be effectively changed for desired applications just by tuning the structure of the cationic and/or anionic part of ILs. Furthermore, these eco-friendly designer materials can function as electrolytes or solvents depending on the application. Owing to the distinctive properties such as low volatility, high thermal and electrochemical stability, and better ionic conductivity, ILs are nowadays immensely used in a variety of energy applications, particularly in the development of green and sustainable energy storage and conversion devices. Suitable ILs are designed for specific purposes to be used as electrolytes and/or solvents for fuel cells, lithium-ion batteries, supercapacitors (SCs), and solar cells. Herein, we have highlighted the utilization of ILs as unique green designer materials in Li-batteries, fuel cells, SCs, and solar cells. This review will enlighten the promising prospects of these unique, environmentally sustainable materials for next-generation green energy conversion and storage devices. Ionic liquids have much to offer in the field of energy sciences regarding fixing some of the world's most serious issues. However, most of the discoveries discussed in this review article are still at the laboratory research scale for further development. This review article will inspire researchers and readers about how ILs can be effectively applied in energy sectors for various applications as mentioned above.

Increasing Chemotherapeutic Efficacy Using pH-Modulating and Doxorubicin-Releasing Injectable Chitosan-Poly(ethylene glycol) Hydrogels

Modulation of pH is crucial to maintaining the chemical homeostasis of biological environments. The irregular metabolic pathways exhibited by cancer cells result in the production of acidic byproducts that are excreted and accumulate in the extracellular tumor microenvironment, reducing the pH. As a consequence of the lower pH in tumors, cancer cells increase the expression of metastatic phenotypes and chemotherapeutic resistance. A significant limitation in current cancer therapies is the inability to locally deliver chemotherapeutics, leading to significant damage to healthy cells in systemic administration. To overcome these challenges, we present an injectable chitosan-poly(ethylene glycol) hydrogel that is dual-loaded with doxorubicin and sodium bicarbonate providing alkaline buffering of extracellular acidity and simultaneous chemotherapeutic delivery to increase chemotherapeutic efficacy. We conducted in vitro studies of weak base chemotherapeutic and alkaline buffer release from the hydrogel. The release of doxorubicin from hydrogels increased in a low-pH environment and was dependent on the encapsulated sodium bicarbonate concentration. We investigated the influence of pH on the doxorubicin efficacy and viability of MCF-7 and MDA-MB-231 breast cancer cell lines. The results show a 2- to 3-fold increase in IC50 values from neutral pH to low pH, showing decreased cancer cell viability at neutral pH as compared to acidic pH. The IC50 results were shown to correlate with a decrease in intracellular uptake of doxorubicin at low pH. The proposed hydrogels were confirmed to be nontoxic to healthy MCF-10A mammary epithelial cells. Rheological studies were performed to verify that the dual-loaded hydrogels were injectable. The mechanical and release properties of the hydrogels were maintained after extended storage. The chemotherapeutic activity of doxorubicin was evaluated in the presence of the proposed pH-regulating hydrogels. The findings suggest a promising nontoxic, biodegradable hydrogel buffer delivery system that can achieve two simultaneous important goals of local acidosis neutralization and chemotherapeutic release.

Diagnostic efficacy of chest CT imaging in diagnosis of COVID-19 cases based on duration of symptoms

Background

Chest computed tomography (CT) imaging provides results more rapidly and with higher sensitivity than reverse transcription polymerase chain reaction in diagnosis of COVID-19.

Aim

To evaluate diagnostic efficacy of chest CT imaging in diagnosis of COVID-19 cases based on age and duration of symptoms.

Materials and Methods

A retrospective study conducted during December 2020 to June 2021 in a tertiary care hospital, India. Total 495 patients with typical clinical symptoms of COVID-19, reverse transcription polymerase chain reaction positive for COVID-19 and had undergone chest CT imaging were included. Descriptive statistical analysis was performed for all the variables. Receiver operating characteristic curve analysis was used to determine threshold value of chest CT severity score (CT_SS) based on duration of symptoms and age to diagnose COVID-19.

Results

Mean age of patients was 61.86 ± 10.77 years and 367 (71.4%) patients were male. Ground glass opacities were observed in 456 (92.1%) patients and in 332 (67.1%) patients, multilobes were affected. Total CT_SS showed positive correlation with age (r = 0.257) and duration of symptoms (r = 0.625). Total CT_SS >6 after a duration of 2 days of symptoms identified COVID-19 cases with sensitivity 90.8% (95% confidence interval [CI]: 87.5%-93.5%) and specificity 84.6% (95% CI: 76.2%-90.9%). Total CT_SS >11 in patients aged more than 60 years identified COVID-19 cases with sensitivity 47.4% (95% CI: 41.2%-53.6%) and specificity 87.3% (95% CI: 82.3%-91.4%).

Conclusion

Threshold value of CT_SS determined will help to expedite diagnosis of COVID-19 patients by the clinicians in an early stage especially in India and other developing countries which have a high patient volume and limited health resources.

Case Report of Male Pseudohermaphroditism (Androgen Insensitivity Syndrome): Congenital Disorder of Sexual Differentiation

INTRODUCTION

A broad spectrum of anomalies of sexual differentiation may exist at birth, which can be unreported until adolescence. A 17-year-old patent with female phenotype came with complaints of primary amenorrhea. On imaging (ultrasound and MRI) uterus and bilateral ovaries were absent. Small blind-ending vaginal pouch was noted along with features suggesting bilateral cryptorchidism. No definite male external genitalia/scrotal sac was seen except for subtle rudimentary bulbo-cavernous muscles. Karyotyping confirmed 46 XY consistent with Male Pseudohermaphroditism.

MATERIALS

Male pseudohermaphroditism refers to a condition that affects 46, XY individuals with differentiated testes who exhibit varying degrees of feminization. In these cases there is a spectrum of external genitalia; some individuals are completely phenotypically female. Androgen insensitivity syndrome (AIS), also known as the testicular feminization syndrome, results from end-organ resistance to androgens, particularly testosterone. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of imaging, cytogenetic and biochemical studies. Ultrasound and MRI studies are extremely useful to diagnose such conditions at the earliest as these patients have an increased incidence of malignancy in the undescended testes. The treatment is influenced by genital tissue responsiveness to androgens and reconstructive surgical procedures. There is a need for counselling regarding pubertal development, sexual performance and fertility.

RESULT

A 17year old patent came with complaints of primary amenorrhea. On examination patient has normal external female genitalia, with developed breast. On laboratory correlation, it shows high testosterone level: 881 ng/dL and Normal progesterone level: 0.182 ng/mL. On karyotyping, it shows 46XY karyotype. On USG: Uterus is not well appreciated. There is iso-echogenic oval shaped soft tissue seen in bilateral inguinal regions with vascularity within-likely to be gonads. On MRI: Absence of uterus and bilateral ovaries are confirmed with evidence of symmetrical oval-shaped soft tissue lesions identified within bilateral inguinal canals - consistent with bilateral cryptorchidism. Male pseudohermaphroditism refers to a condition that affects 46, XY individuals with differentiated testes who exhibit varying degrees of feminization.

CONCLUSION

In cases of male pseudohermaphroditism, there is a spectrum of external genitalia; some individuals are completely phenotypically female, whereas others appear to be normal males with varying spermatogenesis and/or pubertal virilization. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of cytogenetic, biochemical, and radiologic studies. Sonographic and radiographic studies are often used initially to evaluate such conditions. Male pseudohermaphrodites all possess testes yet exhibit incomplete virilization of the genital ducts and/or external genitalia. The findings depend on the underlying defect. Complete androgen insensitivity (testicular feminization) is an X-linked recessive disorder in which the absence of cytoplasmic testosterone receptors prevents specific gene activation and subsequent differentiation of the external genitalia. In this disorder, the external genitalia are completely feminized, while in the other forms of male pseudohermaphroditism various degrees of virilization occur. The absence of internal female genital tract structures reflects the synthesis of active Mullerian regression factor by the testes, which may be maldescended. Multiplanar MR images will confirm the absence of a uterus and demonstrate intraabdominal or inguinal testes. Integrated imaging in the form of ultrasound, genitography and MRI is important in demonstrating the anatomy, classification, possible effects or congenital malformations in other organs, warning patients of any risk of neoplasia and guiding the clinician to plan other investigations, hormonal replacement or reconstruction surgery if required. References Tanaka YO, Mesaki N, Kurosaki Y, et al. Testicular feminization: role of MRI in diagnosing this rare male pseudohermaphroditism. J Comput Assist Tomogr 1998;22(6):884-888. Nakhal RS, Hall-Craggs M, Freeman A, et al. Evaluation of retained testes in adolescent girls and women with complete androgen insensitivity syndrome. Radiology 2013;268(1):153-160.

Ionic Liquids: Environmentally Sustainable Materials for Energy Conversion and Storage Applications.. [DOI: 10.21203/rs.3.rs-2212222/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Ionic liquids (ILs), known as green designer solvents, have shown tremendous application potential in various fields of science and technology. Their unusual and unique physicochemical properties have attracted researchers worldwide from interdisciplinary research areas. ILs possess high boiling point and low volatility, that makes them suitable environmentally benign candidates for many potential applications. The more important aspect associated with ILs is their physicochemical properties can be effectively changed for desired applications just by tuning the structure of the cationic and/or anionic part of ILs. Furthermore, these environmentally benign designer materials can be used as both electrolytes as well as solvents depending on the requirement. Owing to thedistinctive properties such as low volatility, high thermal and electrochemical stability, better ionic conductivity, ILs are nowadays immensely used in variety of energy applications, particularly in the development of green and sustainable energy storage and conversion devices. Suitable ILs are designed for specific purposesto be used as electrolytes and/or solvents for fuel cells, lithium-ion batteries, supercapacitors(SCs) and solar cells. Herein, we have highlighted the utilization of ILs as unique green designer materials in Li-batteries, fuel cells,SCs and solar cells. This review will enlighten the promising prospects of these unique environmentally sustainable materials for next-generation green energy conversion and storage devices.

(Cd,Mg)Te crystals for picosecond-response optical-to-x-ray radiation detectors

We demonstrate a photodetector sensitive to both optical and x-ray picosecond pulses based on our in-house grown cadmium magnesium telluride (Cd,Mg)Te single crystal. Specifically, we developed In-doped Cd_0.96Mg_0.04Te material and discuss its femtosecond optical photoresponse, as well as the detector performance, such as <100-pA dark current and up to 0.22-mA/W responsivity for 780-nm wavelength optical radiation. The detector exposed to Ti fluorescence (K alpha) x-ray pulses at 4.5 keV, generated by a free-electron laser beam with the central energy of 9.8 keV and <100 fs pulse width, exhibited readout-electronics-limited 200-ps full-width-at-half-maximum photoresponse, demonstrating that it is suitable for coarse timing in free-electron laser x-ray/optical femtosecond pump-probe spectroscopy applications.

Diversity of rumen microbiota using metagenome sequencing and methane yield in Indian sheep fed on straw and concentrate diet

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Bacteroidetes and Firmicutes were most prevalent bacteria in the sheep rumen.

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Bacteroidetes were negatively correlated with the Euryarchaeota.

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Archaea constituted ∼2.5% of the ruminal microbiota.

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Methanobrevibacter gottschalkii constituted > 50% of the ruminal archaea.

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Hydrogenotrophic methanogens distribution leads to the variability in methane yield.

An in vivo study aiming to investigate the rumen methanogens community structure was conducted in Mandya sheep fed on straw and concentrate diet. The ruminal fluid samples were collected and processed for unravelling the rumen microbiota and methanogens diversity. Further, the daily enteric methane emission and methane yield was also quantified using the SF₆ tracer technique. Results indicated that the Bacteroidetes (∼57%) and Firmicutes (25%) were two prominent affiliates of the bacterial community. Archaea represented about 2.5% of the ruminal microbiota. Methanobacteriales affiliated methanogens were the most prevalent in sheep rumen. The study inveterate that the ruminal archaea community in sheep is composed of 9 genera and 18 species. Methanobrevibacter represented the largest genus of the archaeome, while methylotrophs genera constituted only 13% of the community. Methanobrevibacter gottschalkii was the prominent methanogen, and Methaobrevibacter ruminantium distributed at a lower frequency (∼2.5%). Among Methanomassiliicoccales, Group 12 sp. ISO4-H5 constituted the most considerable fraction (∼11%). KEGG reference pathway for methane metabolism indicated the formation of methane through hydrogenotrophic and methylotrophic pathways, whereas the acetoclastic pathway was not functional in sheep. The enteric methane emission and methane yield was 19.7 g/d and 20.8 g/kg DMI, respectively. Various species of Methanobrevibacter were differently correlated, and the distribution of hydrogenotrophic methanogens mainly explained the variability in methane yield between the individual sheep. It can be inferred from the study that the hydrogenotrophic methanogens dominate the rumen archaeal community in sheep and methylotrophic/aceticlastic methanogens represent a minor fraction of the community. Further studies are warranted for establishing the metabolic association between the prevalent hydrogenotrophs and methylotrophs to identify the key reaction for reducing methane emission.

Performance of prognostic scores in prediction of 30-day postoperative mortality in COVID-19 patients after emergency surgery: A retrospective cohort study

Background

: Risk assessment with prognostic scoring, though important, is scarcely studied in emergency surgical patients with COVID-19 infection.

Methods and Material

We conducted a retrospective cohort study on adult emergency surgical patients with COVID-19 infection in our institute from 1 May 2020 to 31 October 2021 to find the 30-day postoperative mortality and predictive accuracy of prognostic scores. We assessed the demographic data, prognostic risk scores (American Society of Anesthesiologists-Physical Classification (ASA-PS), Sequential Organ Failure Assessment (SOFA), Quick SOFA (qSOFA), Physiologic and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) and Portsmouth-POSSUM (P-POSSUM) scores), surgical and anesthetic factors. We assessed the postoperative morbidity using the Clavien-Dindo scale and recorded the 30-day mortality. Correlation of prognostic scores and mortality was evaluated using Univariate Cox proportional hazards regression, receiver operating characteristic curve (ROC), Youden's index and Hosmer- Lemeshow goodness of fit model.

Results

Emergency surgery was performed in 67 COVID-19 patients with postoperative complication and 30-day mortality rate of 33% and 19%, respectively. A positive qSOFA and ASAPS IIIE/IVE had a 9.03- and 12.7-times higher risk of mortality compared to a negative qSOFA and ASA-PS IE/IIE (P &lt; 0.001), respectively. Every unit increase of SOFA, POSSUM and P-POSSUM scores was associated with a 50%, 18% and 17% higher risk of mortality, respectively. SOFA, POSSUM and P-POSSUM AUCROC curves showed good discrimination between survivors and non-survivors (AUC 0.8829, 0.85 and 0.86, respectively).

Conclusions

SOFA score has a higher sensitivity to predict 30-day postoperative mortality as compared to POSSUM and P-POSSUM. However, in absence of a control group of non-COVID-19 patients, actual risk attributable to COVID-19 infection could not be determined.

Observational study to compare the effect of altitude on cardiopulmonary reserves of different individuals staying more than 6 weeks at 10,000 ft and 15,000 ft

Background

The variation in heights beyond high altitude has different effects on the cardiorespiratory profile of individuals because of variation in oxygen density with every thousand feet. This study was planned to analyze and compare the effects of difference in altitudes on cardiorespiratory profile from anesthesiologist's point of view.

Methods

A multicenter observational study was done involving two different groups of 600 patients at 10,000 ft (Group A) and 15,000 ft (Group B). Observation and comparison of oxygen saturation, 6-min walk test, and breath holding time was carried out.

Results

Fifty-five percent of subjects in Group A had oxygen saturation of more than 93% in comparison to 5.5% in Group B. This was statistically significant (P < 0.001). Two percent of subjects in Group A in comparison to 63.5% of Group B had oxygen saturation of less than 88% (P < 0.001). Percentage increase of more than 15% of heart rate was found to be statistically significant in all the age groups. Overall, 3.8% of individuals in Group A had breath holding time less than 15 s in comparison to 16.6% of individuals in Group B (P value < 0.001).

Conclusion

The study demonstrates that there is a significant fall in oxygen saturation, significant rise in the heart rate in 6-min walk test, and significant fall in the breath holding time in the group located at 15,000 ft. Heights beyond 10,000 ft should be restricted to life and limb saving surgeries, and logistics should be focused more on "scoop and run" than "stay and play" policy.

Comparison of enteric methane yield and diversity of ruminal methanogens in cattle and buffaloes fed on the same diet

An in vivo study was conducted to compare the enteric methane emissions and diversity of ruminal methanogens in cattle and buffaloes kept in the same environment and fed on the same diet. Six cattle and six buffaloes were fed on a similar diet comprising Napier (Pennisetum purpureum) green grass and concentrate in 70:30. After 90 days of feeding, the daily enteric methane emissions were quantified by using the SF6 technique and ruminal fluid samples from animals were collected for the diversity analysis. The daily enteric methane emissions were significantly greater in cattle as compared to buffaloes; however, methane yields were not different between the two species. Methanogens were ranked at different taxonomic levels against the Rumen and Intestinal Methanogen-Database. The archaeal communities in both host species were dominated by the phylum Euryarchaeota; however, Crenarchaeota represented <1% of the total archaea. Methanogens affiliated with Methanobacteriales were most prominent and their proportion did not differ between the two hosts. Methanomicrobiales and Methanomassillicoccales constituted the second largest group of methanogens in cattle and buffaloes, respectively. Methanocellales (Methanocella arvoryza) were exclusively detected in the buffaloes. At the species level, Methanobrevibacter gottschalkii had the highest abundance (55-57%) in both the host species. The relative abundance of Methanobrevibacter wolinii between the two hosts differed significantly. Methanosarcinales, the acetoclastic methanogens were significantly greater in cattle than the buffaloes. It is concluded that the ruminal methane yield in cattle and buffaloes fed on the same diet did not differ. With the diet used in this study, there was a limited influence (<3.5%) of the host on the structure of the ruminal archaea community at the species level. Therefore, the methane mitigation strategies developed in either of the hosts should be effective in the other. Further studies are warranted to reveal the conjunctive effect of diet and geographical locations with the host on ruminal archaea community composition.

Regional cardiac dysfunction determined by radiation dose in patients with breast cancer

Background

Subclinical left ventricular (LV) dysfunction by 2D global longitudinal strain (GLS) immediately following radiotherapy (RT) and persisting at 12 months has been described in breast cancer (BC) patients. We hypothesised that persistent LV dysfunction may be regional and correlate with segmental RT.

Methods

Transthoracic echocardiograms were performed at baseline, 6 weeks and 12 months post-RT on 61 chemotherapy-naïve women with left sided BC.

Results

Anterior and anteroseptal regions received the highest radiation dose, and posterior and inferior segments the lowest radiation dose (Figure 1). Within each region, there was a progressive increase in the radiation dose received from base to apex. At 6 weeks, the greatest reduction in strain was observed in the anterior and anteroseptal regions, with the most significant reduction in strain in the apical segments. At 12 months, despite improvement in strain, the percentage reduction in strain was similar. There was a significant interaction between both region and segment, on the percentage change in strain at 6 weeks (p&lt;0.001) and at 12 months (p=0.007). Pairwise comparisons of apical to basal percentage change in strain demonstrated the most significant reductions in the anterior region at 6 weeks and 12 months (Table 1).

Conclusions

RT causes segmental myocardial dysfunction, with areas receiving the highest RT demonstrating the largest impairment in strain, with these changes persisting at 12 months. Long term correlation with adverse events is required.

Figure 1. Radiation dose by region and segment

Funding Acknowledgement

Type of funding source: None

EXPLORING THE METABOLICALLY ACTIVE RUMEN MICROBIOTA AND ITS FIBROLYTIC POTENTIAL IN CROSSBRED CATTLE FED ON FIBROUS DIET THROUGH METATRANSCRIPTOMICS

The rumen wharves conglomerate of symbiotic fibrolytic microflora with the potential to produce repertoire of carbohydrate-active enzymes to elicit the degradation of recalcitrant plant lignocellulosic complex into simpler forms that can be utilized by the host. A metatranscriptomics approach was adopted to explore the metabolically active microbiota and the transcripts involved in the deconstruction of lignocellulose in Indian crossbred cattle rumen. The experimental animals were fed with mixed diet for a period of twenty-one days and the total RNA was isolated from the rumen digesta using a modified total RNA extraction protocol. After mRNA enrichment, the cDNA libraries were subjected to sequencing under Illumina HiSeq platform and generated about 2.89 GB of raw sequences. The contig assembly was accomplished using two different tools and the redundant sequences were removed before further processing. A total of 133,930 orfs were predicted from the assembled contigs using MetaGeneMark tool and the taxonomic affiliation of orfs were achieved using MEGAN 6.0 Community Edition. A total of 17 bacterial, 5 eukaryotic and 1 archaeal phylum were identified from rumen metatranscriptomic dataset. Phylum Bacteroidetes were acknowledged as the most abundant and metabolically active rumen bacterial populations in cattle rumen with 36,414 orfs corresponding to it, followed by Firmicutes with 6,349 orfs. Further, MEGAN annotation of metatranscriptomic data at species level revealed that Prevotella brevis and Prevotella ruminicola as the most metabolically active bacterial populations representing 4,022 and 2,725 orfs each. The functional annotation of metatranscriptomic data using COG database revealed that a large number of transcripts (~16%) were corresponding to translation, ribosomal structure and biogenesis and carbohydrate transport and metabolism (15%). dbCAN annotation of rumen metatranscriptomic data identified and classified 5,267 transcripts belonging to 168 CAZyme families (GH-52%, GT-26%, CBM-14%, CE-6%, PL-2% and AA-0%). The microbial community analysis of the CAZyme encoding transcripts using M5NR database revealed that a significant proportion of CAZymes were contributed by genera Prevotella (37%) and Bacteroides (21%). The cattle rumen microbiome metatranscriptome analysis presented in this study facilitated the detection of large number of transcripts encoding diverse CAZymes that actively take part in the hydrolysis of plant lignocellulose complex that may be useful for improving livestock and biofuel generation.

Effect of silkworm (Bombyx mori) pupae oil supplementation on enteric methane emission and methanogens diversity in sheep

In vitro and in vivo studies were conducted to examine the effect of silkworm pupae oil on methane (CH₄) emission and methanogens diversity. Five graded levels (2, 4, 6, 8 and 10%) of silkworm pupae oil were tested in vitro. Eighteen Mandya adult sheep were divided into three groups. All the animals were fed on similar basal diet except the oil supplementation in test groups. Oil level for supplementation was decided on the basis of in vitro study. In vitro study indicated a reduction of 22% in CH₄ production with 2% oil supplementation. Animals in test groups were supplemented with oil (2%) either daily (CON) or intermittently (INT) on every alternate week for all the seven days. A significant reduction of 17-20% in enteric CH₄ emission (g/d) was achieved due to oil supplementation in sheep. However, No variation was established between test groups CON and INT. In present study, Methanobrevibacter was major genus contributed ∼90% of the total rumen methanogens; whilst Methanobrevibacter gottschalkii was the most abundant methanogens species. Abundance of Methanobrevibacter ruminantium was affected with the oil supplementation. It can be concluded that the silkworm pupae oil at 2% can decrease CH₄ emission by 15-20%.

Controlling Microarray Feature Spreading and Response Stability on Porous Silicon Platforms by Using Alkene-Terminal Ionic Liquids and UV Hydrosilylation

In an attempt to develop reversible sensors based on ionic liquid/porous silicon (IL/pSi) platforms, we introduce an approach using task-specific, alkene-terminal ILs (AT-ILs) for direct grafting to the hydrogen-passivated as prepared-pSi (ap-pSi) surface via UV-hydrosilylation to address previous shortcomings associated with IL pattern impermanence (i.e., spread). By employing photoluminescence emission (PLE) and Fourier-transform infrared (FT-IR) imaging measurements, we demonstrate that the covalent grafting of AT-ILs onto the ap-pSi surface via photochemical hydrosilylation not only mitigates such feature spreading but also greatly improves PLE pattern stability. Significantly, we have discovered that, upon hydrosilylation, the resulting contact pin printed IL features remain stable to repeated challenges by toluene vapors, demonstrating the utility of AT-IL hydrosilylation for producing high-fidelity microarray features on pSi toward robust optical sensory microarrays.

Fluorescence Quenching of Dipyrenylalkanes by an Electron/Charge Acceptor

Compounds possessing two fluorophoric moieties may exhibit dual fluorescence, one characterizing the monomeric fluorophore unit and the other characterizing the intramolecular aggregate. Fluorescence quenching of two dipyrenylalkanes, 1,3-bis(1-pyrenyl)propane [1Py(3)1Py] and 1,10-bis(1-pyrenyl)decane [1Py(10)1Py] having different alkyl chains separating the two termini pyrenyl groups that are capable of forming an intramolecular excimer, by an electron/charge-accepting quencher, nitromethane, is investigated in four different solvents-nonpolar (cyclohexane (CH)), polar-aprotic (acetonitrile (ACN)), polar-protic (ethanol (EtOH)), and chlorinated (dichloromethane (DCM))-under ambient conditions. For a given probe in a solvent, fluorescence from the monomer and the intramolecular excimer are quenched with similar efficiencies; the efficiency of quenching is higher for the probe with the longer alkyl chain separating the two fluorophores. Quenching efficiency is significantly higher in chlorinated solvent DCM. The bimolecular quenching rate constants for intramolecular excimer, however, are either comparable or lower for the longer alkyl chain compound. It is suggested that, while the donor electronic excited-state energetics is more favorable for the long alkyl chain compound, the approach of the quencher to the intramolecular excimer appears to be hindered by the presence of a longer alkyl chain.

Effect of ionic liquid on the fluorescence of an intramolecular exciplex forming probe

The effects of ionic liquid addition on the spectroscopic properties of a pyrene-tryptophan-containing fluorescent intramolecular complex in polar-aprotic and polar-protic solvents, specifically, acetonitrile and ethanol, are assessed. Two ionic liquid sets, consisting of seven different ionic liquids, were explored; set 1 comprised three imidazolium-containing ionic liquids paired with different anions while set 2 consisted of varying cations, namely, imidazolium, pyrrolidinium, ammonium, and pyridinium, partnered with a common anion, bis(trifluoromethylsulfonyl)imide ([Tf2N-]). The results provided herein reveal that all ionic liquids explored behave as quenchers, however, the imidazolium-, pyrrolidinium-, and ammonium-containing ionic liquids selectively quenched the fluorescence from the exciplex while the monomer emission from pyrene was largely unaffected relative to exciplex emission. Conversely, the pyridinium ionic liquid, significantly quenched the fluorescence from both the pyrene monomer and the pyrene-tryptophan exciplex, as was expected. The observed quenching is demonstrated to originate from the cations of the ionic liquids and is, in general, more efficient for an imidazolium ionic liquid that contains an acidic proton in the C2 position. Stern-Volmer plots of the exciplex quenching demonstrate a complex quenching mechanism that does not appear to follow any conventional quenching models with the data best fit to an exponential equation. Furthermore, time-resolved fluorescence measurements reveal that the quenching is not dynamic in nature as the recovered decay times do not systematically decrease with increasing ionic liquid concentration, suggesting a possible static quenching mechanism. Thus, the formation of a "dark" ensemble is proposed, in which the ionic liquid cations complex with or crowd around the exciplex, quenching the intramolecular energy transfer.

P353 Structural, functional, and electromechanical alterations in patients with paroxysmal atrial fibrillation compared to healthy controls

Background and Methods

We sought to evaluate the clinical and echocardiographic differences between healthy controls and paroxysmal atrial fibrillation (AF) patients. Clinical and echocardiographic parameters (performed in sinus rhythm) in 46 paroxysmal AF patients were compared with a departmental database of 83 health controls.

Results

AF patients were older and had increased body size (Table 1). 39/46 (84%) of AF patients had hypertension and 23/46 (50%) had diabetes mellitus.

AF patients had increased left ventricular (LV) mass, and reduced diastolic function (lower e’ and increased E/e’ ratio) when compared to healthy controls. Left atrial (LA) volumes were significantly increased in the AF group. All strain parameters – reservoir, conduit, and contractile strain – were impaired in AF patients compared to controls. LA mechanical dispersion (MD) was significantly increased in AF patients. A ratio of indexed LA volume/LA reservoir strain was significantly higher in AF patients over controls.

The duration of AF had an inverse correlation with LA reservoir strain (Fig 1) (r=–0.78; p &lt; 0.001).

Conclusions

Compared to healthy controls, patients with paroxysmal AF have significant structural, functional and electromechanical alterations. LA strain is significantly impaired in paroxysmal AF and correlates with AF duration.

Table 1. Echocardiographic parameters Parameter Controls (mean ± SD) AF patients (mean ± SD) P value Age (years) 48 ± 18 58 ± 14 0.001 Body surface area (m2) 1.9 ± 0.2 2 ± 0.2 0.014 LV mass (g) 178 ± 48 223 ± 68 &lt;0.001 Average e’ velocity (cms-1) 10.3 ±2.7 8.1 ± 2.2 &lt;0.001 E/e’ 7.4 ± 1.9 9.3 ± 3.4 0.001 Indexed LA end systolic volume (ml/m2) 27.2 ± 7.1 39.0 ± 11.6 &lt;0.001 LA ejection fraction 55.2 ± 10.4 48.5 ± 14.0 0.007 LA functional index 43.7 ± 14.6 29.8 ± 14.3 &lt;0.001 LA reservoir strain (%) 34.3 ± 6.8 27.9± 8.1 &lt;0.001 LA conduit strain (%) 18.4 ± 6.2 13.5 ± 4.7 &lt;0.001 LA contractile strain (%) 15.9 ± 3.9 14.4 ± 5.5 0.007 LA mechanical dispersion (ms) 25.8 ± 9.6 30.9 ± 11.6 0.018 Indexed LA volume / Reservoir strain ratio 0.8 ± 0.3 1.6 ± 0.9 &lt;0.001 LV = left ventricular; LA = left atrium; SD = standard deviation

Abstract P353 Figure. Fig 1. AF duration vs. Reservoir strain

P970 Significant differences in atrial structural and functional parameters leading to differing mechanisms of atrial fibrillation in athletes compared to non-athletes

Methods

36 endurance athletes in sinus rhythm, with a previous history of AF (ATH-AF) were compared to age and gender matched endurance athletes with no prior history of AF (ATH), non athletes with paroxysmal AF (NONATH-AF) and age and gender matched healthy controls (CONTROL). A detailed transthoracic echocardiogram was performed with all groups in sinus rhythm, with detailed left atrial (LA) and left ventricular (LV) measurements, including strain analysis.

Results

All athletes had increased LA and LV size when compared with healthy controls (Table 1). Non athletes with paroxysmal AF had increased LA size when compared with controls. However, indexed LA/LV ratio was preserved in athletes and similar to healthy individuals, whilst AF patients had significantly increased LA/LV ratio. Athletes with AF had higher e’ velocity and lower E/e’, whereas e’ was reduced and E/e’ elevated in non-athlete AF patients.

Athletes had impaired LA reservoir and contractile strain, and reduced LV global longitudinal strain (GLS) compared with healthy controls.

Conclusions

Compared to healthy controls, athletes have reduced LA and LV strain, with preserved LV diastolic function and LA/LV ratio. In contrast, altered diastolic function with differential increase in LA volume was observed in AF patients. The increased risk of AF in athletes is likely mediated by different mechanistic processes other than an atrial myopathy consequent to diastolic dysfunction as observed in non-athletes with AF.

Table 1. LA and LV parameters Parameter ATH-AF ATH NONATH-AF CONTROL P value LVEDV indexed (ml/m2) 84 ± 12 79 ± 14 57 ± 10 51 ± 13 &lt;0.001 LVESV indexed (ml/m2) 35 ± 6 34 ± 7 25 ± 8 27 ± 33 0.02 LV ejection fraction (%) 58 ± 4 56 ± 4 56 ± 10 58 ± 8 0.586 LV global longitudinal strain (%) 19.2 ± 1.7 18.9 ± 2.1 21 ± 3.1 21.7 ± 2.9 &lt;0.001 e’ vel (cm/s) 10 ± 2 10 ± 3 8 ± 2 9 ± 2 0.007 E/e’ 5.7 ± 1.3 5.9 ± 1.8 9.1 ± 3.3 7.5 ± 1.5 &lt;0.001 LAV max indexed (ml/m2) 45 ± 11 43 ± 12 38 ± 11 27 ± 8 &lt;0.001 Indexed LAV/LVEDV ratio 0.5 ± 0.1 0.6 ± 0.2 0.7 ± 0.2 0.5 ± 0.1 &lt;0.001 LA reservoir strain (%) 27.2 ± 4.8 28.2 ± 3.7 27.9 ± 8.4 33.2 ± 7.0 &lt;0.001 LA conduit strain (%) 14.2 ± 4.5 14.4 ± 4.0 14.9 ± 5.5 16.6 ± 6.3 0.182 LA contractile strain (%) 13.0 ± 3.1 13.8 ± 3.6 13.0 ± 5.1 16.6 ± 3.1 &lt;0.001 LV = left ventricular, LAV = left atrial volume, LA = left atrial

P1504 Inter-vendor comparison of left atrial 2-dimensional strain using multilayer analysis

BACKGROUND

Left atrial strain (LAS) is increasingly being accepted as a marker of left atrial function. Different vendors utilise different techniques of measuring LAS in echocardiography.

AIMS

To determine the difference between multilayer endocardial and mid-myocardial measurements of LA strain on General Electric (GE) Echopac compared to the TOMTEC system which tracks endocardial strain.

METHODS

Peak reservoir left atrial strain (LAS) was measured on 50 healthy controls using the two different echocardiographic software packages. GE Echopac (v201) 2D-speckle tracking echocardiography technique (LV package) was used to measuremid-myocardial (GE-mid) and endocardial (GE-endo) LAS. This was compared to LAS measurement using TOMTEC (v4.6) which uses an endocardial tracking technique. LAS was measured in 4ch and 2ch views and average biplane strain measurement was obtained.

RESULTS

The mean of GE-mid LAS was 36.3 ± 6.3%, GE-endo LAS was higher with a mean of 44.1 ± 8.0%, while TOMTEC LAS was 42.1 ± 6.3 %. GE-mid and GE-endo LAS correlated well with TOMTEC LAS (r = 0.9, p &lt; 0.001 for both). On Bland-Altman Analysis, GE-mid LAS measurements were systematically lower than TOMTEC LAS (mean difference -5.77), whereas GE-endo LAS had no systematic bias (mean difference 1.99).

CONCLUSIONS

Mid-myocardial peak reservoir left atrial strain, which is routinely measured using GE Echopac software, systematically underestimates LAS as compared to TOMTEC LAS or GE endocardial LAS. This suggests that serial follow up of LAS measurements for patients should be performed on the same software.

P1783 Concealed structural abnormalities detected by 2D speckle tracking strain echocardiography persist post ablation in patients with idiopathic ventricular arrhythmias

Background

Idiopathic ventricular arrhythmias (IVA) occurs in patients without overt heart disease. 2D speckle tracking strain echocardiography parameters, including global longitudinal strain (GLS) and mechanical dispersion (MD), have been shown to predict ventricular arrhythmias. It is unclear if the abnormalities are due to structural substrate abnormality, or substrate abnormality consequent to electrical alterations. Aim: We sought to assess whether patients with IVA have impaired left ventricular (LV) strain indices, and if so, whether these persist following successful treatment with radiofrequency ablation (i.e. correction of electrical alteration). Methods: 2D strain analysis was performed (in sinus rhythm) in 23 consecutive patients with IVA (no structural heart disease by cardiac magnetic resonance imaging (MRI); Group A) prior to electrophysiological mapping/ablation, and compared to 23 age and gender matched healthy controls (Group B). Follow up echocardiography and multiday Holter monitoring was performed 12 months post ablation. Results: Baseline characteristics were similar for indexed LV end diastolic volume (EDV) and ejection fraction (EF) (p = 0.1 for both) (Table 1). LV GLS was lower (p = 0.03) and LV MD was increased (p = 0.002) in the IVA group prior to treatment. At follow up, 18 patients (78%) (Group C) remained free of ventricular arrhythmias – in these patients, LV GLS improved and was similar to controls (p = 0.217); however, LV MD remained significantly increased at 12 months compared to controls (p = 0.009). In the 5 patients (22%) (Group D) that continued to have ventricular arrhythmias at follow up, both LV GLS (p = 0.04) and LV MD (p = 0.008) remained significantly impaired compared to controls. Conclusion: Despite demonstrable absence of structural abnormalities with cardiac MRI, 2D strain can detect subtle alterations in myocardial contraction heterogeneity. Furthermore, 12 months post successful ablation treatment, the increase in MD persists. This suggest the presence of subtle substrate abnormality that results in IVA. In uncured patients, both myocardial deformation parameters remain impaired, suggesting the need for close future surveillance of these patients. Long term follow up with greater number of patients is required to further validate these findings.

Table 1. Echocardiographic parameters Group Indexed LVEDV (ml/m2) LVEF (%) LV GLS (%) LV MD (ms) IVA (Group A) 55 ± 15 61 ± 5 -19.9 ± 3* 44 ± 12* Controls (Group B) 54 ± 14 64 ± 7 -21.2 ± 2 33 ± 9 Group C 12 months follow up -21.7 ± 3 42 ± 11* Group D 12 month follow up -19.8 ± 2* 43 ± 11* * denotes p &lt; 0.05

Unprecedented Intramolecular Association-Induced Fluorescence in Tryptophan-Conjugated Peptidomimetics

We report herewith tryptophan (Trp)-conjugated peptidomimetics that show intramolecular through-space association between the Trp units. Our investigation revealed that the proximal placement of Trp can lead to the emergence of a new and unanticipated fluorescent entity constituting a Trp-Trp dimer. Proton-induced modulation of fluorescence is a consequence of this work. Investigations with control compounds unequivocally revealed that the fluorescence property is not originated from the localized excited state but from the unprecedented Trp-Trp intramolecular dimer in the ground state itself. The present findings will initiate the biophysical scientists to have a relook at the fluorescence properties of Trp-containing proteins.

Synthesis of K–Pd doped NiCo2O4−δ by reactive calcination route for oxidation of CO–CH4 emissions from CNG vehicles

The present study is devoted to formulating a doped spinel catalyst by a novel route of calcination for the oxidation of the CO–CH₄ mixture emitted from compressed natural gas (CNG) vehicles.