Optical and electronic properties of MgPc-Ch-diisoQ blend organic thin film as an active layer for photovoltaic cells.

Organic photovoltaic cells are a promising technology for generating renewable energy from sunlight. These cells are made from organic materials, such as polymers or small molecules, and can be lightweight, flexible, and low-cost. Here, we have created a novel mixture of magnesium phthalocyanine (MgPc) and chlorophenyl ethyl diisoquinoline (Ch-diisoQ). A coating unit has been utilized in preparing MgPc, Ch-diisoQ, and MgPc-Ch-diisoQ films onto to FTO substrate. The MgPc-Ch-diisoQ film has a spherical and homogeneous surface morphology with a grain size of 15.9 nm. The optical absorption of the MgPc-Ch-diisoQ film was measured, and three distinct bands were observed at 800-600 nm, 600-400 nm, and 400-250 nm, with a band gap energy of 1.58 eV. The current density-voltage and capacitance-voltage measurements were performed to analyze the photoelectric properties of the three tested cells. The forward current density obtained from our investigated blend cell is more significant than that for each material by about 22%. The photovoltaic parameters (Voc, Isc, and FF) of the MgPc-Ch-diisoQ cell were found to be 0.45 V, 2.12 µA, and 0.4, respectively. We believe that our investigated MgPc-Ch-diisoQ film will be a promising active layer in organic solar cells.

Synthesis of novel Cu/Fe based benzene Dicarboxylate (BDC) metal organic frameworks and investigations into their optical and electrochemical properties.

In the recent past Metal-organic frameworks (MOFs) based thin films have demonstrated superior performance in various technological applications such as optical and optoelectronic devices, electrochemical energy storage, catalysis, and sensing. Herein we report tuning the optical performance of stable complexes using Cu and Fe metal ions with carboxylate benzene dicarboxylic (BDC), leading toward the formation of novel MOF structures. The formation of Cu-BDC and Fe-BDC were confirmed by XRD and SEM studies. The thermal stability of two MOFs was investigated, indicating that, the Cu-BDC is more stable than Fe-BDC. Further, the optical properties were investigated in the wavelength range 325-1100 nm, and the Fe-BDC exhibited greater optical transmission properties than Cu-BDC by 33 %, as investigated by Wemple-DiDomenico and Tauc models. The dispersion parameters related to optical studies for Cu-BDC were better in comparison to Fe-BDC, which could be attributed to the increase in Cu valence electrons due to an increase in the number of cations. The electrochemical behavior in terms of CV measurements shows the presence of pseudo capacitance in both Fe-BDC and Cu-BDC MOFs. The improved CV performance of Cu-BDC MOF suggests that it could be used as a storage material. This work successfully demonstrates the tailoring of optical properties related to MOF thin films through the formation of stable complexes using BDC as a potential material for the fabrication of OLED's and Solar cells. The improved CV performance suggests that these MOF based materials could be used as anodes in fabrication of batteries or supercapacitors.

Expression of concern: Design and development of highly sensitive PEDOT-PSS/AuNP hybrid nanocomposite-based sensor towards room temperature detection of greenhouse methane gas at ppb level.

Expression of concern for 'Design and development of highly sensitive PEDOT-PSS/AuNP hybrid nanocomposite-based sensor towards room temperature detection of greenhouse methane gas at ppb level' by Syed Khasim et al., RSC Adv., 2021, 11, 15017-15029. DOI https://doi.org/10.1039/D1RA00994J.

Synchrotron-based operando X-ray diffraction and X-ray absorption spectroscopy study of LiCo0.5Fe0.5PO4 mixed d-metal olivine cathode.

Lithium-ion batteries based on high-voltage cathode materials, such as LiCoPO4, despite being promising in terms of specific power, still suffer from poor cycle life due to the lower stability of common non-aqueous electrolytes at higher voltages. One way to overcome this issue might be decreasing the working potential of the battery by doping LiCoPO4 by Fe, thus reducing electrolyte degradation upon cycling. However, such modification requires a deep understanding of the structural behavior of cathode material upon lithiation/delithiation. Here we used a combination of operando synchrotron-based XRD and XAS to investigate the dynamics of d-metal local atomic structure and charge state upon cycling of LiCo0.5Fe0.5PO4 mixed d-metal olivine cathode material. Principal components analysis (PCA) of XAS data allowed the extraction of spectra of individual phases in the material and their concentrations. For both Co and Fe two components were extracted, they correspond to fully lithiated and delithiated phases of LixMPO4 (where M = Fe, Co). Thus, we were able to track the phase transitions in the material upon charge and discharge and quantitatively analyze the M2+/M3+ electrochemical conversion rate for both Fe and Co. Rietveld's refinement of XRD data allowed us to analyze the changes in the lattice of cathode material and their reversibility upon (de)lithiation during cycling. The calculation of DFT and Bader charge analysis expects the oxygen redox procedure combined with d-metals redox, which supplements iron charge variations and dominates at high voltages when x < 0.75 in LixCoFePO4.

Enhancement of Gamma-ray Shielding Properties in Cobalt-Doped Heavy Metal Borate Glasses: The Role of Lanthanum Oxide Reinforcement.

The direct influence of La3+ ions on the gamma-ray shielding properties of cobalt-doped heavy metal borate glasses with the chemical formula 0.3CoO-(80-x)B2O3-19.7PbO-xLa2O3: x = 0, 0.5, 1, 1.5, and 2 mol% was examined herein. Several significant radiation shielding parameters were evaluated. The glass density was increased from 3.11 to 3.36 g/cm3 with increasing La3+ ion content from 0 to 2 mol%. The S5 glass sample, which contained the highest concentration of La3+ ions (2 mol%), had the maximum linear (µ) and mass (µm) attenuation coefficients for all photon energies entering, while the S1 glass sample free of La3+ ions possessed the minimum values of µ and µm. Both the half value layer (T1/2) and tenth value layer (TVL) of all investigated glasses showed a similar trend of (T1/2, TVL)S1 > (T1/2, TVL)S2 > (T1/2, TVL)S3 > (T1/2, TVL)S4 > (T1/2, TVL)S5. Our results revealed that the S5 sample had the highest effective atomic number (Zeff) values over the whole range of gamma-ray energy. S5 had the lowest exposure (EBF) and energy absorption (EABF) build-up factor values across the whole photon energy and penetration depth range. Our findings give a strong indication of the S5 sample's superior gamma-ray shielding characteristics due to the highest contribution of lanthanum oxide.

Design and development of highly sensitive PEDOT-PSS/AuNP hybrid nanocomposite-based sensor towards room temperature detection of greenhouse methane gas at ppb level.

Herein, we present fabrication of a novel methane sensor based on poly (3,4-ethylenedioxythiophene:poly (styrene sulfonic acid)) (p-PEDOT-PSS) and gold nanoparticles (AuNPs) treated with dimethyl sulfoxide (DMSO) and Zonyl using a spin coating technique. The nanocomposite films were further post treated with H2SO4 to improve the charge transport mechanism. The structural and morphological features of the composites were analyzed through scanning electronic microscopy, transmission electron microscopy, Fourier transform infra-red spectroscopy, UV-Vis spectroscopy and thermogravimetric analysis. Treatment with organic solvents and post treatment of H2SO4 significantly enhances the conductivity of the composite to 1800 S cm-1. The fabricated sensor shows an excellent sensing response, fast response and recovery time along with acceptable selectivity towards methane gas at ppb concentrations. Due to a simple fabrication technique, excellent conductivity, superior sensing performance and improved mechanical properties, the sensor fabricated in this study could potentially be used to detect greenhouse methane gas at low concentrations.

Simultaneous antegrade dual AV node conduction initiates AV nodal re-entrant tachycardia (a rare initiation mechanism).

Typical atrioventricular nodal reentrant tachycardia (AVNRT) is the most common paroxysmal supraventricular tachycardia among adults. The concept of dual pathway physiology remains widely accepted, although this physiology likely results from the functional properties of anisotropic tissue within the triangle of Koch, rather than anatomically distinct tracts of conduction. AVNRT is typically induced with anterograde block over the fast pathway and conduction over the slow pathway, with subsequent retrograde conduction over the fast pathway. On rare occasions, anterograde AV node conduction occurs simultaneously through fast and slow pathways resulting in two ventricular beats in response to one atrial beat. We report a case of AVNRT where the tachycardia is always induced by the same mechanism described above. Successful ablation was achieved by slow pathway modification.

The ECG role in identifying the etiology of tachycardia-induced cardiomyopathy (TIC).

Tachycardia-induced cardiomyopathy (TIC) is a well recognized entity of heart failure (HF) and various mechanisms due to tachyarrhythmias have been postulated to be responsible for impaired cardiac contractility. Previously reported cases showed reversibility of such disorders whenever stable cardiac rhythm is maintained adequately and we report on a 16-year-old boy who has been diagnosed to have TIC, which was misinterpreted initially as sinus tachycardia secondary to dilated cardiomyopathy and heart failure. A complete recovery of his left ventricular function was achieved by radiofrequency catheter ablation and highlights the importance of a 12-lead electrocardiogram (ECG) assessment in such patients.

Coronary sinus diverticulum as a cause of resistant posteroseptal pathway ablation.

Coronary sinus (CS) anomalies such as diverticulum, persistent left superior vena cava or CS ostium dilatation are predominantly found in patients with accessory pathway-related tachycardias. Diverticulum of the proximal CS found in 7-11% of patients with postero-septal or left posterior manifests accessory pathways. We reported a 28 year old gentleman with manifested postero-septal accessory pathway, who underwent repeat electrophysiological study (EPS) and radiofrequency ablation for previously failed ablation. Huge CS diverticulum was identified by angiography as a reason for resistant accessory pathway. Successful RF ablation was achieved at the neck of the diverticulum without complications. Other associated anomalies were ruled out by cardiac computerized tomography (CT) and trans-esophageal echocardiography.

The importance of utilizing 24-h Holter monitoring as a non-invasive method of predicting the mechanism of supraventricular tachycardia.

Despite the emergence of advanced invasive technology in identifying the various types of arrhythmia mechanisms, 24-h ambulatory electrocardiogram monitoring as a non-invasive method remains an invaluable informative tool in delineating such mechanisms. Furthermore, one observational study has supported the utilization of 24-h Holter monitoring in exploring AV Node (AVN) characteristics sufficiently in correlation with invasive studies when limited to patients without Wolf Parkinson White syndrome showing a positive predictive value of 98% in their supraventricular tachycardia (SVT) assessment (Fukuda et al., 2005). We describe in this report suspected tachycardia initiation mechanism in three SVT cases based on 24-h Holter recordings. Premature atrial contraction with subsequent AVN fast pathway conduction block initiated the common type AVN re-entrant tachycardia (AVNRT). Dual AVN physiology was documented during the electrophysiological studies in all three cases and a definitive therapy was achieved by the AVN slow pathway modification.

Controlling rate and rhythm increases feasibility of CT angiography in atrial fibrillation.

A woman, aged 48 years, with severe rheumatic mitral stenosis and uncontrolled permanent atrial fibrillation (AF) underwent preoperative assessment of coronary arteries. Invasive coronary angiography was not possible because of occluded common iliac artery and bilateral radial spasm. Transesophageal echocardiogram showed a very large mobile left atrial appendage clot, precluding cardioversion. The severe motion artifacts during cardiac CT angiography (64 slices) due to atrial fibrillation were overcome by controlling rhythm and rate through insertion of a temporary pacemaker via right femoral vein, and slowing heart rate below 65 beats per minute by intravenous metoprolol (25 mg) and verapamil (5 mg). Clear pictures of all coronary arteries as well as the left atrial appendage clot were obtained. The temporary pacemaker was removed after eight hours. Uneventful mechanical mitral valve replacement and maze procedure were performed and the patient was discharged in a stable condition.

Relationship between breast-feeding duration and acute respiratory infections in infants.

OBJECTIVE: To study the relationship of breast-feeding duration on the frequency of respiratory tract infections in infants during the first 2 years of life. METHODS: A retrospective study where the files of infants randomly selected from Shamasan Primary Health Care Center were analyzed for different related factors and frequencies of respiratory infections. RESULTS: The mean duration of lactation was shorter than in previous national reports (5.1 +/- 3.4 months). The frequencies of respiratory infections were high in the first 2 years reaching an average of 9.2 +/- 4.1 attacks per infant. The lower respiratory tract suffered more frequent attacks than the upper averaging a rate of 5.6 +/- 2.6 attacks per infant compared to 3.7 +/- 2.2 attacks per infant. The multiple regression models pointed out to highly significant predictors for respiratory infection rates: Lactation duration (p < 0.001) for the 2 years rates, child rank (p < 0.001) for the first year rates and family income (p < 0.001) for the 2nd year rates. CONCLUSION: The lactation duration has an important relation to the frequency of respiratory infections in infancy. Every effort should be made to encourage and support longer duration of breast-feeding.

The pattern of hearing impairment among schoolboys in an Institute for deaf subjects.

OBJECTIVE: The aim of this study was to study the pattern of deafness among boys of Al-Amal Institutes for the Deaf in Abha, the capital city of Asir Region, Southwestern Saudi Arabia. METHODS: All students (n=155) were subjected to full otoscopic and audiometric examinations, and the type and degree of deafness were graded according to the recommendation of the British Society of Audiology. Computerized tomography scan was carried out to exclude congenital inner ear deformity, and specific Igm antibodies assay for TORCHS was carried out when the history of intrauterine infection was positive or suggestive. RESULTS: More than 97% of students had sensori-neural hearing loss of various grades (55% profound, 28% severe and 14.5% moderate), while congenital conductive deafness constituted 3% of all cases. Residual hearing was reported for 43% of cases. There was delayed identification of deafness with an inverse relation between the age of identification of deafness and its severity (F = 227.66, P < 0.001). Prematurity (30%), intrauterine infection (17%) and heredity (15.5%) were the most frequently encountered causes of deafness. Postnatal causes accounted for only 20%, mostly due to meningitis 12%, other childhood fevers 5% and trauma 2.5%. Deafness of unknown cause constituted 12% of all cases. CONCLUSION: The preventable causes of deafness in the region has not yet been overcome, a finding that will necessitate more efforts to upgrade the prenatal and perinatal health care. Late identification of hearing impairment will make the improvement in the audiology screening for infants the priority need.

The pattern of hearing impairment among schoolboys in an Institute for deaf subjects.

OBJECTIVE: The aim of this study was to study the pattern of deafness among boys of Al-Amal Institutes for the Deaf in Abha, the capital city of Asir Region, Southwestern Saudi Arabia. METHODS: All students (n=155) were subjected to full otoscopic and audiometric examinations, and the type and degree of deafness were graded according to the recommendation of the British Society of Audiology. Computerized tomography scan was carried out to exclude congenital inner ear deformity, and specific Igm antibodies assay for TORCHS was carried out when the history of intrauterine infection was positive or suggestive. RESULTS: More than 97% of students had sensori-neural hearing loss of various grades (55% profound, 28% severe and 14.5% moderate), while congenital conductive deafness constituted 3% of all cases. Residual hearing was reported for 43% of cases. There was delayed identification of deafness with an inverse relation between the age of identification of deafness and its severity (F = 227.66, P < 0.001). Prematurity (30%), intrauterine infection (17%) and heredity (15.5%) were the most frequently encountered causes of deafness. Postnatal causes accounted for only 20%, mostly due to meningitis 12%, other childhood fevers 5% and trauma 2.5%. Deafness of unknown cause constituted 12% of all cases. CONCLUSION: The preventable causes of deafness in the region has not yet been overcome, a finding that will necessitate more efforts to upgrade the prenatal and perinatal health care. Late identification of hearing impairment will make the improvement in the audiology screening for infants the priority need.

Tympanostomy tubes and prophylactic antibiotic ear drops.

Full text is available as a scanned copy of the original print version.

Pharyngolaryngo-esophagectomy with immediate gastric pull-up.

BACKGROUND: This paper documents our experience with patients who underwent laryngopharyngoesophagectomy with immediate gastric pull-up procedures. PATIENTS AND METHOD: Fifteen patients with carcinoma of the hypopharynx and cervical esophagus underwent total laryngopharyngo-esophagectomy with immediate gastric pull-up procedures over a period of nine years at the Asir Central Hospital in the southwestern region of Saudi Arabia. RESULTS: The most common complication was cervical fistula, which with its sequelae occurred in 40%. Postoperative function in terms of swallowing ability was good but rehabilitation of speech was poor. The overall hospital mortality was 7%, and the crude survival rate was 40%. The most common cause of long-term failure was the recurrence of the disease. CONCLUSION: The success of this operative procedure depends on wide surgical excision of cancer along with rapid reconstruction of alimentary canal.

Do systemic corticosteroids effectively treat obstructive sleep apnea secondary to adenotonsillar hypertrophy?

To determine if pediatric obstructive sleep apnea syndrome (OSAS) caused by adenotonsillar hypertrophy (ATH) could be treated by a short course of systemic corticosteroids, we conducted an open-label pilot study in which standardized assessments of symptomatology, OSAS severity, and adenotonsillar size were performed before and after a 5-day course of oral prednisone, 1.1+/-0.1 (+/-SE) mg/kg per day. Outcome measures included symptom severity, adenotonsillar size, and polysomnographic measures of OSAS. Selection criteria included age from 1 to 12 years, ATH, symptomatology suggesting OSAS, an apnea/hypopnea index (AHI) > or = 3/hour, and intent to perform adenotonsillectomy. Only one of nine children showed enough improvement to avoid adenotonsillectomy. Symptomatology did not improve after corticosteroid treatment but did after removal of tonsils and adenoids. Polysomnographic indices of OSAS severity did not improve after corticosteroid treatment. After corticosteroids, tonsillar size decreased in only two patients, adenoidal size was only marginally reduced, and the size of the nasopharyngeal airway was not significantly increased. These results suggest that a short course of prednisone is ineffective in treating pediatric OSAS caused by ATH.

Idiopathic facial nerve paralysis (Bell's Palsy) in the Asir Region.

This is a prospective study of idiopathic facial nerve paralysis (Bell's palsy) in the southwest region of Saudi Arabia (Asir Region). A total of 321 patients were seen at the Facial Nerve clinic in the department of Otolaryngology, Head and Neck Surgery between January 1992 and December 1995. They comprised 159 males and 162 females. The peak frequency of the condition occurred in the third decade, and 223 of the cases (69%) occurred during the winter months (November to March). Three hundred and twelve patients had single unilateral attacks, six had ipsilateral recurrent attacks, while three had contralateral recurrent attacks. No cases of bilateral attacks were observed. The main associated factor was exposure to cold draft. Only 14 patients (4%) had some residual functional deficit six months after the onset of paralysis.

Tympanoplasty: Factors influencing surgical outcome.

We reviewed the records of 183 patients who had undergone myringoplasty during a six year period at the Asir Central Hospital (ACH). This study was limited to cases of repair of uncomplicated perforation of tympanic membrane that did not require ossiculoplasty or mastoidectomy. One hundred and thirty-four (73.2%) were successful myringoplasty and 78 (75.7%) patients had their hearing improved postoperatively. Various factors liable to influence the success rate such as status of middle ear, size and site of perforations, surgical approach and presence of tympanosclerosis were analyzed. Only status of the middle ear and the presence of tympanosclerosis at the time of surgery were found to have a major effect on the final outcome of surgery.