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This review briefly introduces the degradation mechanisms according to the RH and summarizes various approaches to stabilize halide perovskites. An outlook for research directions of halide perovskites is also suggested.

Persistent or recurrent angina after percutaneous coronary intervention (PCI) has substantial patient morbidity and economic impact. As knowledge of the pathophysiology of this condition has evolved, new tools for accurate diagnosis and treatment have become available. We provide a current, comprehensive review of mechanisms of post-PCI angina, diagnostic strategies, and therapeutic options.The routine use of functional testing during PCI may enable more accurate revascularization. Coronary vasomotor disorders commonly cause angina after PCI in the absence of obstructive epicardial CAD. Invasive coronary vasoreactivity testing can enable phenotype-guided therapy of coronary vasomotor disorders with improvement in angina. Multiple nonpharmacologic modalities to treat refractory angina are under development. A comprehensive approach to the diagnosis of persistent or recurrent angina after PCI with noninvasive and invasive techniques is required. An individualized, phenotype-guided management using lifestyle, pharmacologic, and nonpharmacologic modalities is necessary to optimize outcomes.

We present a detailed study of the highly obscured active galaxy NGC 4507, performed using four Nuclear Spectroscopic Telescope Array (NuSTAR) observations carried out between May and August in 2015 (~ 130 ks in total). Using various phenomenological and physically motivated torus models, we explore the properties of the X-ray source and those of the obscuring material. The primary X-ray emission is found to be non-variable, indicating a stable accretion during the period of the observations. We find the equatorial column density of the obscuring materials to be ~ 2 x 10^24 cm^-2 while the line of sight column density to be ~ 7 - 8 x 10^23 cm^-22. The source is found to be deeply buried with the torus covering factor ~ 0.85. We observe variability in the line-of-sight column density on a timescale of < 35 days. The covering factor of the Compton-Thick material is found to be ~ 0.35, in agreement with the results of recent X-ray surveys. From the variability of the line-of-sight column density, we estimate that the variable absorbing material is likely located either in the BLR or in the torus., 20 pages, 15 figures, 8 tables, accepted for publication in MNRAS

Development of a low-cost portable colorimetric nanosensor for real field pollution monitoring.

The potentiality of Förster resonance energy transfer (FRET) for studying molecular interactions inside biological tissues with improved spatial (Angström) and temporal (picosecond) resolution is well established. On the other hand, the efficacy of diffuse reflectance spectroscopy (DRS) that uses optical radiation in order to determine physiological parameters including haemoglobin, and oxygen saturation is well known. Here we have made an attempt to combine diffuse reflectance spectroscopy (DRS) with picosecond-resolved FRET in order to show improvement in the exploration of molecular contacts in biological tissue models. We define the technique as ultrafast time-resolved diffuse reflectance spectroscopy (UTRDRS). The illuminated photon of the fluorophore from the surface of the tissue-mimicking layers carries the hidden information of the molecular contact. In order to investigate the validation of the Kubelka-Munk (KM) formulism for the developed UTRDRS technique in tissue phantoms, we have studied the propagation of incandescent and picosecond-laser light through several layers of cellulose membranes. While picosecond-resolved FRET in the diffuse reflected light confirms the hidden nano-contact (4.6 nm) of two different dye layers (8-anilino-1-naphthalenesulfonic acid and Nile blue), high-resolution optical microscopy on the cross-section of the layers reveals the proximity and contacts of the layers with limited spatial resolution (∼300 nm). We have also investigated two biologically relevant molecules, namely carboxyfluorescein and haemoglobin, in tissue phantom layers in order to show the efficacy of the UTRDRS technique. Overall, our studies based on UTRDRS in tissue mimicking layers may have potential applications in non-invasive biomedical diagnosis for patients suffering from skin diseases.

Tremendous efforts have been devoted to wearable mechanical sensors to meet growing needs in healthcare sensors and electronic skins.

Right ventricular outflow tract (RVOT) obstruction is present in a variety of congenital heart disease states including tetralogy of Fallot, pulmonary atresia/stenosis and other conotruncal abnormalities etc. After surgical repair, these patients develop RVOT residual abnormalities of pulmonic stenosis and/or insufficiency of their native outflow tract or right ventricle to pulmonary artery conduit. There are also sequelae of other surgeries like the Ross operation for aortic valve disease that lead to right ventricle to pulmonary artery conduit dysfunction. Surgical pulmonic valve replacement (SPVR) has been the mainstay for these patients and is considered standard of care. Transcatheter pulmonic valve implantation (TPVI) was first reported in 2000 and has made strides as a comparable alternative to SPVR, being approved in the United States in 2010. We provide a comprehensive review in this space–indications for TPVI, detailed procedural facets and up-to-date review of the literature regarding outcomes of TPVI. TPVI has been shown to have favorable medium-term outcomes free of re-interventions especially after the adoption of the practice of pre-stenting the RVOT. Procedural mortality and complications are uncommon. With more experience, recognition of risk of dreaded outcomes like coronary compression has improved. Also, conduit rupture is increasingly being managed with transcatheter tools. Questions over endocarditis risk still prevail in the TPVI population. Head-to-head comparisons to SPVR are still limited but available data suggests equivalence. We also discuss newer valve technologies that have limited data currently and may have more applicability for treatment of native dysfunctional RVOT substrates.

Excess consumption of fluoride (F–) through drinking water and its detrimental effects on human health have been a serious global concern. Herein, we have developed a facile and highly sensitive spectroscopic technique for selective detection of F– in aqueous media using aluminum phthalocyanine chloride (AlPc-Cl) as a sensor. The absorbance and steady-state fluorescence intensity of AlPc-Cl has been found to decrease in the presence of F– which has been used as a marker for the determination of F– concentration in water. The structural change in AlPc-Cl after addition of F– has been thoroughly studied by using ¹⁹F nuclear magnetic resonance spectroscopy. Our detailed steady-state and time-resolved fluorescence studies reveal that the quenching mechanism is static in nature. The response of the sensor is found to be linear over the F– concentration regime from 0 to 6 ppm with a detection limit of 0.05 ppm. Additionally, it shows an excellent selectivity as well as an insignificant change in sensitivity, even in the presence of interfering iron and aluminum ions. Based on the detailed photophysical study, we have further developed a low cost and portable prototype device that shows an excellent sensitivity with the detection limit of 0.10 ppm.

BACKGROUND: Hirschsprung's disease is one of the most important causes of functional intestinal obstruction in the paediatric age group. The clinical characteristics of patients with Hirschsprung's disease at a tertiary referral centre were studied over a 22-month period. Aims and Objectives: To study the demography, including Age, Sex, various clinical presentations, types, segment involved, surgery, complications and survival in patients with Hirschsprung's disease at a tertiary care referral centre in Rajasthan, India. Materials and methods: This was a prospective observational study between October 2018 and June 2020, over 22 months, at tertiary referral centre in North-Western India. Clinical data were tabulated, various presentations of the disease were studied, intra-operative ndings were noted and post-operative course was studied. Results: 82 cases of Hirschsprung disease were admitted, of which 66 were male and 16 were female. Of these, 10 presented in the neonatal age group, 25 during infancy (1 month to 1 year of age) and the rest – 47 patients presented beyond infancy. The commonest symptoms in infants and older children was chronic constipation, whereas delayed passage of meconium, abdominal distension and bilious vomiting were among the common symptoms in neonates. The patients underwent exploratory laparotomy with multiple biopsies and diversion colostomies. 43 patients underwent the denitive procedure. In all the 43 patients, Martin's modication of Duhamel's procedure, was the surgery performed. Complications included persistence of constipation, enterocolitis, and a few cases of anastomotic leak.

Background: Congenital diaphragmatic hernia (CDH) is a developmental defect, in which there is herniation of abdominal contents into the thoracic cavity. This causes pulmonary hypoplasia and pulmonary hypertension to varying degrees. The clinical prole of CDH neonates at a tertiary care institute were studied over a period of 22 months between October 2018 to June 2020. Aims and objectives: To study the demography, including Age, Sex, birth weight, types, associated anomalies, surgery, complications and survival in CDH patients at a tertiary care referral centre in Rajasthan, India. Materials and methods: This was a prospective observational study between October 2018 and June 2020, over 1 year and 9 months, at tertiary referral centre in North-Western India. Clinical data, radiological ndings, pre-operative conditions were studied, intra-operative ndings were noted and post-operative course was studied. Intravenous Sildenal was administered and their effects on clinical improvement was noted. Results:102 cases of CDH were admitted, of which 62 were male and 40 were female. Of these cases, 78 underwent surgical repair, while the rest died prior to surgery. Majority (99) were left sided CDH. And majority (59) were without sac. Contents which were commonly encountered included Stomach, small and large intestine, spleen, liver. Patients who were administered with intravenous sildenal showed clinical improvement in the pulmonary hypertension. Patients with CDH require urgent management of the respiratory distress and pulmonary hypertension, in order to improve their survival.

Intracardiac and intravascular thrombi are associated with significant morbidity and mortality. Although surgery remains the gold standard treatment option, these patients often have multiple comorbidities that can make surgical options challenging. With advancements in catheter-based technologies, there are now percutaneous treatment options for these patients. The AngioVac is a percutaneous vacuum-assisted thrombectomy device FDA-approved for removal of intravascular debris that uses a venovenous extracorporeal membranous oxygenation circuit with a filter. Use of this device has now been reported in the removal of right atrial or iliocaval thrombi, debulking tricuspid vegetations, removal of vegetations from implantable cardiac devices, and pulmonary embolism.

Aims Persistent mitral valve regurgitation (MR) after continuous flow left ventricular assist device implantation (cfLVAD) is associated with pulmonary hypertension and right ventricular failure with variable effects on survival across published studies. The aim of this study is to determine the incidence and predictors of persistent MR at 6‐month follow‐up after cfLVAD implantation and its impact on survival, haemodynamics, right ventricular function, and morbidity. Methods and results We performed a retrospective review of all adult cfLVAD recipients from January 2012 to June 2017 at a single tertiary university hospital with follow‐up until April 2019. Primary outcome was to compare survival between patients with no‐to‐mild compared with persistent moderate‐to‐severe MR at 6 months. Secondary outcomes included right heart failure (RHF), length of stay, re‐hospitalizations, and composite of death, transplant, and pump exchange during the length of follow‐up. Final analytic sample was 111 patients. The incidence of persistent moderate or severe MR at 6 months was 26%. Significant predictors of persistent MR at 6 months were left atrium dimension and volume. The group with persistent moderate‐to‐severe MR at 6 months had higher incidence of RHF at 6 months (45% vs. 25%, P = 0.04). There was no difference in survival at 1 year between the groups (no‐to‐mild MR 85.5%, moderate‐to‐severe MR 87.9%, Wilcoxon P‐value = 0.63). There was no difference in re‐hospitalizations, length of stay, composite of death, transplant, or pump exchange during the length of follow‐up between the comparison groups. Conclusions Persistent moderate‐to‐severe MR after cfLVAD implantation is present in one fourth of patients and is associated with increased incidence of RHF, higher mean pulmonary pressure, and pulmonary capillary wedge pressure with no effect on 1 year survival. Increased left atrium size was associated with persistent moderate‐to‐severe MR at 6 months.

Background: The drug cinnarizine is used in the treatment of vertigo and migraine. The main drawback is its very low water solubility which causes unpredictable bioavailability. Solubility is better in acidic pH. Therefore, gastro-retentive formulation would be beneficial to improve the bioavailability of the drug. Objective: The objective of the study was to prepare floating microballoons of cinnarizine which would float in the gastric fluid and release the drug in a sustained manner. Methods: Microballoons were prepared by diffusion solvent evaporation technique using polymers (Eudragit® S100, Eudragit® RLPO, Eudragit RL®100), characterised by FTIR, XRD, DSC and optimized by sequential simplex design. For optimization, formulations were graded with respect to formulation efficiency (percentages of yield, sphericity and drug content) and performance index (buoyancy and dissolution efficiency), from which the overall response of the formulations was determined. Finally, the optimized formulation was radiolabelled with 99mTc-MIBI and fed to Wistar albino rats and was evaluated for gastric retention by gamma scintigraphic study. Results: FTIR studies indicated drug and polymers were compatible. DSC and XRD analysis confirmed that the drug was in amorphous state in the formulation. SEM studies confirmed the sphericity of the microballoons. Formulation N7 showed the best overall response (65.61) which was the nearest to the target. Gamma scintigraphic study confirmed that the formulation was retained in the stomach for more than 5 h. Conclusion: The results indicated that floating microballoons of cinnarizine would stay in the stomach for prolonged period and thereby improve the bioavailability of the drug.

Pulmonary hypertension (PH) has been described in myeloproliferative disorders; monoclonal plasma cell disorder such as polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes syndrome; and plasma cell dyscrasias such as multiple myeloma and amyloidosis. We describe 4 cases of PH likely due to pulmonary vascular involvement and myocardial deposition from light chain deposition disease, amyloidosis, and multiple myeloma. On the basis of our clinical experience and literature review, we propose screening for plasma cell dyscrasia in patients with heart failure with preserved ejection fraction, unexplained PH, and hematological abnormalities. We also recommend inclusion of cardiopulmonary screening in patients with monoclonal gammopathy of undetermined significance.

Congenital pouch colon (CPC) is classified on the basis of anatomic morphology into five types. Congenital segmental intestinal dilatation associated with anorectal malformation (ARM) is very rare. We are adding two neonates of CPC type 2 associated with segmental dilatation of the ileum to single similar case described in the literature till date. Temporary stomas with excision of either of the pouches should be considered. “Defective mesenchyme formation during organogenesis” due to abnormal mesenchymal precursor cells is hypothesized as the cause for both ARM and different types of CPC.

BACKGROUND Treatment of congenitally corrected transposition of great arteries (cc-TGA) with anatomic repair strategy has been considered superior due to restoration of the morphologic left ventricle in the systemic circulation. However, data on long term outcomes are limited to single center reports and include small sample sizes. AIM To perform a systematic review and meta-analysis for observational studies reporting outcomes on anatomic repair for cc-TGA. METHODS MEDLINE and Scopus databases were queried using predefined criteria for reports published till December 31, 2017. Studies reporting anatomic repair of minimum 5 cc-TGA patients with at least a 2 year follow up were included. Meta-analysis was performed using Comprehensive meta-analysis v3.0 software. RESULTS Eight hundred and ninety-five patients underwent anatomic repair with a pooled follow-up of 5457.2 patient-years (PY). Pooled estimate for operative mortality was 8.3% [95% confidence interval (CI): 6.0%-11.4%]. 0.2% (CI: 0.1%-0.4%) patients required mechanical circulatory support postoperatively and 1.7% (CI: 1.1%-2.4%) developed post-operative atrioventricular block requiring a pacemaker. Patients surviving initial surgery had a transplant free survival of 92.5% (CI: 89.5%-95.4%) per 100 PY and a low rate of need for pacemaker (0.3/100 PY; CI: 0.1-0.4). 84.7% patients (CI: 79.6%-89.9%) were found to be in New York Heart Association (NYHA) functional class I or II after 100 PY follow up. Total re-intervention rate was 5.3 per 100 PY (CI: 3.8-6.8). CONCLUSION Operative mortality with anatomic repair strategy for cc-TGA is high. Despite that, transplant free survival after anatomic repair for cc-TGA patients is highly favorable. Majority of patients maintain NYHA I/II functional class. However, monitoring for burden of re-interventions specific for operation type is very essential.

CONTEXT: VP Shunt is most commonly used procedure for hydrocephalus but shunt failure is also the common complication in many patients. Endoscopic third ventriculostomy (ETV) is an accepted procedure for the treatment of obstructive hydrocephalus. The aim of our study is to evaluate the success rate AIM AND OBJECTIVE - of ETV in patients of obstructive hydrocephalus formerly treated by ventriculo-peritoneal (VP shunt) shunt. The failure VP shunt was removed before ETV. MATERIALS AND METHOD: This study was conducted between June 2015 and December 2019 in single unit of our department. Twenty one (n=21) patients were enrolled for this study. All patients were admitted with failure of VP shunt. They were known case of non-communicating hydrocephalus previously operated for VP shunt. Six patients were excluded for ETV because CT/MRI show grossly distorted anatomy of ventricles. Endoscopic third ventriculostomy was attempted in 15 patients, but ventriculostomy was done successfully in 10 patients, rests were treated with revision of VP shunt. All patients in this study were radiologically diagnosed RESULTS: case of hydrocephalus due to aqueduct stenosis. They were experienced VP shunt insertion but there were failure of shunt due to any reason. ETV procedures were done successfully in 10 patients. Out of 10 patients one patient needed shunt insertion due ineffective ETV. Shunt revision was done in 11 patients. There was no serious complication during and after ETV procedures. The follow-up period of patients with successful ETV was 6–60 months. This follow-up was uneventful and peaceful for their parents. ETV can be considered as an alternative treatment for the patients w CONCLUSION: ith VP shunt failure with an acceptable success rate of 80%, although long-term follow-up is needed for these patients.

The development of bismuth-based photocatalysts in response to emerging demand for solving environmental problems has attracted immense interest over the past few years. This is owed to their low c...

There are no large reports of comparative outcomes of transcatheter pulmonic valve implantation (TPVI) and surgical pulmonic valve replacement (SPVR). Prospective studies are unlikely to be feasible in the future also. Thus, we utilized a large adult inpatient database to compare the two with respect to temporal trends, in hospital outcomes and costs. Data from the National Inpatient Sample database from 2003 to 2014 was analyzed to extract patients who underwent TPVI and SPVR using unique ICD 9-CM codes. In-hospital outcomes and charges were then analyzed. All charges were converted to 2018 dollars and a loss of wages analysis was performed using the Bureau of Labor Statistics published median weekly wages. A total of 8,449 and 555 SPVR and TPVI discharges were identified. 5.8% SPVR procedures were done in rural setting versus 1.8% of TPVI. Complications including in-hospital mortality (2.3 vs 0.9%; p = 0.02) were higher in SPVR group. Length of stay was significantly shorter for the TPVI group (1 vs 5 days; p0.001), which also contributed to lower loss of wages ($1028.57 vs $6042.86; p0.001) with similar hospital charges. In conclusion, volumes of both TPVI and SPVR are increasing across adult hospitals in the United States, reflecting an overall increase in the adult congenital heart disease population. TPVI offers improved short-term outcomes and decreased loss of wages through shorter recovery time in this real-world database analysis.

Background Patients presenting with hypertensive urgency / emergency (HUE) often have systolic heart failure(SHF). Coronary angiography is routinely done for these patients to rule out obstructive coronary artery disease (Obs-CAD). We performed a retrospective study to investigate predictors of ObsCAD in this population. Methods Patients who underwent angiography to investigate SHF and had hospital admission(s) for HUE in the preceding 6 months were included in the study. Chart review was performed to obtain demographic, clinical and imaging / angiographic data. A risk score was formulated based on multivariable logistic regression analysis. Results 205 patients [age 58.9 ± 14.4 years; 62.4% male; 39.5% diabetic; median EF 25% (Inter Quartile Range: 11)] were included in the study. 33.1% patients (n = 68) had obs-CAD. Patients with obs-CAD were older, diabetic, more likely to have a history of stroke, echocardiographic regional wall motion abnormalities (RWMA) while African Americans were less likely to have obs-CAD. On multivariable analysis, only non-African American race (OR: 2.18; CI: 1.08–4.4) and RWMA (OR: 5.62; CI: 2.47–12.81) remained significant predictors of obs-CAD. A risk score (RANDS) from 0 to 9 was formulated which had a c-statistic of 0.75 with a sensitivity and specificity of 84% and 53% for predicting obsCAD respectively. Conclusion Our results suggest that only a minority of patients with HUE and SHF have obs-CAD. A simple risk score may be used to stratify this population and lower risk individuals may be screened with non-invasive testing instead of invasive catheterization. These results should be validated in large registry populations.

We present the first measurement of the proton–Ω correlation function in heavy-ion collisions for the central (0–40%) and peripheral (40–80%) Au + Au collisions at s NN = 200 GeV by the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). Predictions for the ratio of peripheral collisions to central collisions for the proton–Ω correlation function are sensitive to the presence of a nucleon–Ω bound state. These predictions are based on the proton–Ω interaction extracted from ( 2 + 1 ) -flavor lattice QCD calculations at the physical point. The measured ratio of the proton–Ω correlation function between the peripheral (small system) and central (large system) collisions is less than unity for relative momentum smaller than 40 MeV/c. Comparison of our measured correlation ratio with theoretical calculation slightly favors a proton–Ω bound system with a binding energy of ∼ 27 MeV.

Cardiac allograft vasculopathy (CAV) is a challenging complication of heart transplantation. CAV pathophysiology is incompletely understood, standard screening modalities such as angiography have significant limitations, and currently available therapies have only modest efficacy in preventing progression. Optical coherence tomography is a light-based technique that provides microscopic level catheter-based intravascular imaging and has dramatically expanded our understanding of CAV, demonstrating it to be a complex, heterogeneous, and dynamic process. This review covers characteristics and uses of optical coherence tomography, including vessel characterization, serial use to assess progression of disease, guiding percutaneous intervention, and monitoring response to CAV therapies. We also discuss the potential of optical coherence tomography in providing individualized assessment and enable customized CAV therapies, which may lead to improvements in long-term transplant outcomes.

Plasmonic nanoparticles are of great importance owing to their highly responsive ‘localized surface plasmon resonance’ (LSPR) behaviour to self-agglomeration/aggregation leading to the development of various nanosensors. Herein, we demonstrated the definite self-assembly of citrate functionalized silver nanoparticles (AgNPs) into a one-dimensional linear chain in presence of charged lead ions (Pb2+), one of the most toxic heavy metal pollutants. We have explored detail mechanism using a variety of spectroscopic tools and electron microscopy. The self-aggregation of AgNPs leads to the generation of new LSPR modes due to coupling of nearby existing modes. The conclusion of our experimental findings is duly supported by our developed numerical modelling based on the quasi-static approximation that the generated new LSPR modes are solely due to formation of chain-like aggregation of AgNPs. We have also monitored the LSPR spectra in the presence of other metal ions; however, only Pb2+ found to give such unique self-assembled geometry may due to its high interaction affinity with citrate. These findings play a key role for citrate functionalised AgNPs to be used as a low cost highly selective and sensitive lead ion sensor for potential application in industrial lead pollution monitoring. We have further varied several sensor parameters such as AgNPs size, concentration, and the allowed reaction time for it to be practically implemented as an efficient lead sensor meeting the Environmental Protection Agency recommendations. The possible sensing mechanism of citrate-functionalized silver nanoparticles towards Pb2 + followed by unique chain-like aggregation for potential atmospheric and industrial lead pollution monitoring.

We present the results of a broadband (0.5-78 keV) X-ray spectral study of the persistent Galactic black hole X-ray binary GRS 1758-258 observed simultaneously by Swift and NuSTAR. Fitting with an absorbed power-law model revealed a broad Fe line and reflection hump in the spectrum. We used different flavours of the relativistic reflection model for the spectral analysis. All models indicate the spin of the black hole in GRS 1758-258 is >0.92. The source was in the low hard state during the observation, with the hot electron temperature of the corona estimated to be kT$_e$ ~ 140 keV. The black hole is found to be accreting at ~1.5 % of the Eddington limit during the observation, assuming the black hole mass of 10 $M_{\odot}$ and distance of 8 kpc., 10 pages, 5 figures, 1 table. Accepted for publication in ApJ. Comments are welcome

Excess consumption of fluoride through drinking water and its detrimental effects on human health have been a serious global concern. Therefore, frequent monitoring as well as quantitative determination of fluoride ion (F-) concentration in aqueous media is of vital importance. Herein, we have developed a facile and highly sensitive spectroscopic technique for selective detection of F- in aqueous media using aluminium phthalocyanine chloride (AlPc-Cl) as a sensor. The absorbance as well as steady-state fluorescence intensity of AlPc-Cl has been found to decrease in presence of F- which has been used as a marker for the determination of fluoride ion concentration in water. The structural change in AlPc-Cl after addition of F- has been thoroughly studied by using 19F NMR (Nuclear Magnetic Resonance) spectroscopy. Our detailed steady-state as well as time-resolved fluorescence studies reveal that the quenching mechanism is static in nature due to ground state complexation in between F- and AlPc-Cl molecules. The response of the sensor is found to be linear over the F- concentration regime from 0 to 6 parts per million (ppm) with a detection limit of 0.05 ppm. Additionally, it shows an excellent selectivity as well as an insignificant change in sensitivity even in the presence of interfering iron and aluminium ions. Based on the detailed photophysical study, we have further developed a low cost and portable prototype device which shows an excellent sensitivity with the detection limit of 0.10 ppm. This prototype device has a high prospect for real-time monitoring of fluoride ion concentration especially in remote areas.

We present the long-term X-ray spectral and temporal analysis of a 'bare-type AGN' Ark 120. We consider the observations from XMM-Newton, Suzaku, Swift, and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of several physical parameters, such as the temperature and optical depth of the electron cloud, the size of the Compton cloud, and accretion rate for the last fifteen years. The spectral variations are explained from the change in the accretion dynamics; (b) the X-ray time delay between 0.2-2 keV and 3-10 keV light-curves exhibited zero-delay in 2003, positive delay of 4.71 \pm 2.1 ks in 2013, and negative delay of 4.15 \pm 1.5 ks in 2014. The delays are explained considering Comptonization, reflection, and light-crossing time; (c) the long term intrinsic luminosities obtained using nthcomp, of the soft-excess and the primary continuum show a correlation with a Pearson Correlation Coefficient of 0.922. This indicates that the soft-excess and the primary continuum are originated from the same physical process. From a physical model fitting, we infer that the soft excess for Ark 120 could be due to a small number of scatterings in the Compton cloud. Using Monte-Carlo simulations, we show that indeed the spectra corresponding to fewer scatterings could provide a steeper soft-excess power-law in the 0.2-3 keV range. Simulated luminosities are found to be in agreement with the observed values., Communicated with MNRAS. The revised version will be updated soon. Comments are welcome