A study of the electrical properties of polycrystalline based organic devices

In this thesis, examination of polycrystalline organic based devices such as the Schottky diode and MOS capacitor is carried out. The data is interpreted in terms of a polycrystalline model based mainly on a conventional polysilicon model with slight modifications to fit the organic properties. A brief introduction to the existing charge transport models for organic materials is presented. The most dominant being the variable range hopping model for disordered materials. The disorder analysis is appropriate in the grain boundaries of a polycrystalline material. The distribution of the traps of density of states (DOS) is commonly described by the Gaussian distribution and the associated exponential approximate at low energies. This is a valid assumption for organic semiconductors with low carrier mobility values [N. Sedghi et al., J. Non Crys. Solids 352, 1641, 2006]. Detailed investigation on the temperature effects of the polycrystalline Schottky diode leads to determination of important electrical parameters. Such studies are essential in understanding the conduction processes of the organic device, particularly in terms of trapping effects, which is essential in the development of device models for organic circuitry. Several parameters such as dopant (ND) and carrier concentrations (p), effective mobility (μeff), depletion width (Wdep), effective Debye length (LDe), Meyer Neldel energy (MNE) and the characteristic temperature of the carriers (T0) are extracted from the current-voltage characteristics of the diode. For a soluble derivative of pentacene, 6, 13-triisopropylsilyethynyl pentacene (TIPS) blended with Polytriarylamine (PTAA), the respective values extracted at room temperature are found to be approximately 1017 cm-3, 1.8x10-2 cm2V-1s-1, 185 nm, 11 nm, 31.5 meV and 780 K, respectively. As the temperature falls, the values of most parameters remain constant until a critical temperature. The activation energy also remains constant at approximately 0.3 eV for various applied voltages in saturation. Below this critical temperature, Wdep, LDe and T0 increase whilst μeff, ND/p and characteristic temperature of the states (TC) decrease. Similar analysis is carried out on doped layers of TIPS with a different insulating binder Poly-alpha methylstyrene (PAMS). The value of Wdep, LDe, T0, μeff, ND/p, MNE and TC obtained from such doped Schottky diode are approximately 100 nm, 5 nm, 1200 K, 1x10-2 cm2V-1s-1, 2x1017 cm-3, 35 meV and 400 K, respectively. The Capacitance-Voltage (C-V) analysis on polycrystalline Schottky diodes provides ND of approximately 7.6 x 1016 cm-3, 5.2 x 1014 cm-3 and 2.98 x 1014cm-3 at 500 Hz, 1 kHz and 2 kHz respectively. These ND values are lower than those extracted from current-voltage characteristics and decrease with increasing frequency. This is thought to be due to the low mobility of holes, unable to respond to the signal at higher frequencies. The conduction in polycrystalline organic Schottky diode is proposed using a 2-dimensional (2D) model, which focuses on both the lateral and vertical conduction paths. The organic semiconductor layer is assumed to be relatively thin so that only a single layer of the grain exists between adjacent grain boundaries for the vertical conduction. A two dimensional situation is treated as two separate one dimensional problems that are positioned at right angles to each other. The grain and grain boundaries in the polycrystalline material are explained in terms of two boundary conditions. The variation of potential in grain boundary is the basis in defining the variation of potential in the grains. Conduction under forward bias in the grain and grain boundary is thus established assuming two distributions for the DOS, namely the Gaussian and Laplace. In comparison, Laplace DOS is believed to be a better representation of the distribution of states, where a large number of energy levels are being scanned with applied voltage. The ac properties of a polycrystalline based MOS capacitor are investigated. The frequency and temperature effects on the C-V characteristics of MOS capacitor based on another soluble derivative of pentacene, refered here as S1150, are studied. Equivalent circuits which include the effects of bulk and series resistance due to contact effects are analysed. The bulk resistance (Rb), bulk capacitance (Cb) and series resistance (RS) are found to be approximately 13 kΩ, 760 pF and less than 309 Ω respectively, for an organic film thickness (tOSC) of 27nm. For ND ≈ 3.6 x 1017cm-3 at 1 kHz, the hole mobility is found to be approximately 4.6x10-7cm2V-1s-1. As expected the mobility decreases with increase in frequency. Furthermore, the temperature study of inverse square space charge capacitance (1/CS2) against absolute temperature (T) provides an intercept close to T (~ 330K) instead of TC. A low intercept value indicates a decrease in disorder which suggests that the large grains may be dominating the capacitance

Indigenizing the Postnatal Blues in Pakistani Context: A Psychometric Study

Postnatal Blues is postnatal psychological distress among new mothers. It is marked by partially exasperating physical and affective symptoms having significant etiological relevance for a more debilitating condition named Postnatal Depression. The absence of an assessment protocol for PNBs in Pakistan became the basis for conceptualizing the current research. It attempts to develop a measure for screening mothers for PNBs based on the indigenous expression and manifestation of PNBs in the Pakistani context. Semi-structured interviews elicited a list of 27 items from ten mothers experiencing PNBs and 25 relevant experts. The final list of 21 items, empirically validated by six pertinent experts and piloted on 15 mothers, was further administered to a purposive sample of Pakistani mothers diagnosed with PNBs (N= 88). The known-group validity and cut-off score of the Postnatal Blues Screening Scale (PNBSS) were established through Cohen’s d and Receiver Operating Curve (N= 107), respectively. PNBSS resulted in four factors, namely rudimentary blues, over sensitivity, emotional dysregulation, and somatic and cognitive disquietude with significant known-group validity (effect size = 0.9 -1.1); ROC curve (AUC= 0.853). The participants could not be isolated from their families for stage III assessment, which increases the likelihood of response bias. PNBSS has promising psychometric robustness for both clinical and research purposes. Being the first indigenous scale, PNBSS can serve as a foundation for the psychological assessment regime for Pakistani postnatal mothers and the benchmark for future research. Key Words: Postnatal Blues, Symptomatology, Pakistani Mothers, Puerperium, Indigenous Screening, Scale Development

Binge-Watching as Behavioral Addiction: A Systematic Review

In the recent past, binge-watching has emerged as one of the most prevalent pursuits among adults. Being a relatively new phenomenon, there is a pressing need to examine the literature on the associations of binge watching with various psychological correlates such as cognitive processes, emotional regulation, moods and sleep patterns. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) model was employed for this systematic review. Relevant articles were collected using various databases including Google Scholar, Research Gate and PubMed. This resulted in a collection of 209 articles which were further screened based on the predefined inclusion and exclusion criteria. Out of these articles, 18 met the criteria and were included in the study. The findings revealed noteworthy associations between binge-watching behavior; particularly problematic patterns, and disruptions in mood and emotional dysregulation. The systematic review highlighted that the phenomenon of binge-watching as an addictive and problematic behavior has negative outcomes for individuals such as compromised executive functioning as well as cognitive deficits

Effect Of Zinc And Ingredients Of Protein Supplement On Sperm Parameters And Male Reproductive Hormones- An RCT Study

Abstract Objective: The purpose of this study was to assess the protective effects of zinc against injury to sperm parameters and male reproductive hormones brought on by toxic protein supplement constituents. Methods: 30 male Sprague Dawley rats were used in the study, of which 10 were in Group 1 (given standard laboratory food), 10 were in Group 2, fed standard laboratory food nutritional supplement powder and 10 were in Group 3, fed standard laboratory food, nutritional supplement powder and zinc. Semen Analysis of Male Sprague Dawley rats of all 3 groups was evaluated after 8 weeks. Sperm parameters and serum levels of Male Reproductive Hormones were measured at the beginning and the end of the study. Results: There was a significant decrease (P<0.05) in Mean ± SEM of sperm count millions /ml, sperm motility (%), and normal sperm morphology (%) in Group 2 rats when compared with Group 1. Zinc supplement in Group 3 caused a significant increase (P<0.05) in Mean ± SEM of sperm parameters including sperm count millions /ml, sperm motility (%) and normal sperm morphology (%) as compared to Group 2 rats. Mean ± SEM of serum level of testosterone Hormone, Follicle Stimulating Hormone(FSH), and Luteinizing Hormone(LH) of Group 2 rats showed a significant (P<0.05) decrease when compared with Group 1 rats. However, the use of Zinc in Group 3 rats significantly (P<0.05) increased serum Testosterone, FSH, and LH levels when compared to Group 2. No significant difference was noted between serum levels of Testosterone, in Group 1 and Group 3. Serum levels of FSH and LH in Group 3 rats (484.81+ 78.17 ng/ml) were significantly increased (P<0.05) as compared to Group 1 rats. Conclusion: Regular addition of antioxidant Zinc with protein supplements has the potential to restore normal functions of the male reproductive system.

Effects of different acetylsalicylic acid doses on body organs, histopathology, and serum biochemical parameters in broiler birds

A indústria avícola é afetada por diversas doenças ou estresses. Particularmente devido às aves serem antipiréticas. O ácido acetilsalicílico (AAS) é largamente utilizado com diferentes objetivos que incluem o controle do estresse calórico, bem como a atividade respiratória e digestiva. O propósito deste estudo foi a avaliação dos efeitos benéficos e tóxicos do emprego de diferentes dosagens do AAS em frangos de corte. As variáveis analisadas foram: exame físico, parâmetros bioquímicos, bem como as alterações histopatológicas em seções de tecidos colhidas das aves em um ensaio experimental. O estudo foi conduzido em 60 frangos de corte com um dia de idade adquiridos em um mercado local de Faisalabad que foram recriados nos primeiros 14 dias em idênticas condições. Então no 15º dia as aves foram distribuídas randomicamente em quatro grupos identificados pelos números 1 a 4, com 15 aves em cada grupo. O grupo 4 foi mantido como grupo controle e os grupos 1, 2 e 3 foram tratados com AAS, respectivamente, nas doses de 300, 600 e 1200 mg/L de água de bebida, durante 21 dias. Foram realizadas três amostragens nos dias 21, 28 e 35 pós-tratamento. O peso vivo corpóreo e da carcaça foi registrado em cada amostragem. Em todos os órgãos viscerais foi analisada a presença de alterações patológicas. As amostras de soro sanguíneo foram colhidas para a avaliação bioquímica. O exame histopatológico de todos os órgãos viscerais foi realizado para a observação de alterações microscópicas. A partir da segunda amostragem foi observado um aumento significante (p<0,05) no peso corpóreo na dosagem de 300mg/L. Um significante aumento no peso relativo dos órgãos foi registrado na dosagem de 1200 mg/L. Os grupos tratados com dosagens de 600 e 1200 mg/L de AAS, apresentaram aumento significante dos níveis de AST, ALT e de creatinina quando comparados ao grupo controle. O grupo tratado com 1200 mg/L de AAS apresentou um aumento significante (P,0,05) de uréia, proteína sérica total e de albumina em todas as amostragens. No grupo de alta dosagem foram observados alterações histopatológicas constituídas por aumento dos hepatócitos, aumento dos espaços sinusoidais no fígado, congestão e anormalidades nos espaços glomerulares nos rins, congestão e ruptura alveolar nos pulmões, degeneração das vilosidades e celular nos intestinos A conclusão obtida foi que em frangos de corte uma baixa dosagem do AAS pode ser utilizada por um período de longa duração, apresentando um efeito promotor do crescimento, contudo as doses elevadas determinam toxicidade hepática e renal.The poultry industry suffers from various diseases or stresses. In poultry, apart from being antipyretic, acetylsalicylic acid (ASA) is widely used to cope with different issues including heat stress, and respiratory and digestive orders. This study evaluated the beneficial and toxic effects of ASA at different dose levels in broiler birds. To evaluate these toxic and beneficial effects it is necessary to examine the physical and serum biochemical parameters as well as the histopathological changes with tissue sections taken from broiler birds under experimental trial. This study was conducted on 60 one-day-old broiler chicks purchased from a local market in Faisalabad. Chicks were reared for the first 14 days under similar conditions. On the 15th day, birds were randomly divided into 4 groups (1-4) with 15 birds in each group. Group 4 was kept as control, while groups 1, 2, and 3 were treated with ASA at the dose of 300, 600, and 1200 mg/L of drinking water for 21 days. There were 3 samplings performed at 21, 28, and 35 days post-treatment. The live body weight and carcass weight were noted on each sampling. All the visceral organs were recorded for gross pathological changes. The serum samples were collected for biochemical evaluation. Histopathology of all the visceral organs was performed to observe the microscopic changes. A significant (P<0.05) increase in live body weight at a 300mg/L dose was noted after the first 2 samplings. A significant (P<0.05) increase in the relative organ weight was recorded at 1200 mg/L. The groups treated with ASA 600 and 1200 mg/L showed increased (P<0.05) AST, ALT, and creatinine levels from that of the control group. The group treated with 1200 mg/L of ASA showed increased (P<0.05) urea, serum total protein, and albumin level in all the samplings. Histopathological changes revealed swollen hepatocytes, increased sinusoidal spaces in the liver, congestion and abnormal glomerular spaces in the kidney, congestion and alveolar disruption in the lungs, and generation of villi and cellular degeneration in the intestine in a high-dose group. The study concluded that ASA at a low dose can be used for a long time in broilers and has a growth promontory role, while high-level doses cause hepatorenal toxicity

SARS-CoV-2 variants of concern dominate in Lahore, Pakistan in April 2021

The SARS-CoV-2 pandemic continues to expand globally, with case numbers rising in many areas of the world, including the Indian sub-continent. Pakistan has one of the world’s largest populations, of over 200 million people and is experiencing a severe third wave of infections caused by SARS-CoV-2 that began in March 2021. In Pakistan, during the third wave until now only 12 SARS-CoV-2 genomes have been collected and among these nine are from Islamabad. This highlights the need for more genome sequencing to allow surveillance of variants in circulation. In fact, more genomes are available among travellers with a travel history from Pakistan, than from within the country itself. We thus aimed to provide a snapshot assessment of circulating lineages in Lahore and surrounding areas with a combined population of 11.1 million. Within a week of April 2021, 102 samples were sequenced. The samples were randomly collected from two hospitals with a diagnostic PCR cutoff value of less than 25 cycles. Analysis of the lineages shows that the Alpha variant of concern (first identified in the UK) dominates, accounting for 97.9 % (97/99) of cases, with the Beta variant of concern (first identified in South Africa) accounting for 2.0 % (2/99) of cases. No other lineages were observed. In depth analysis of the Alpha lineages indicated multiple separate introductions and subsequent establishment within the region. Eight samples were identical to genomes observed in Europe (seven UK, one Switzerland), indicating recent transmission. Genomes of other samples show evidence that these have evolved, indicating sustained transmission over a period of time either within Pakistan or other countries with low-density genome sequencing. Vaccines remain effective against Alpha, however, the low level of Beta against which some vaccines are less effective demonstrates the requirement for continued prospective genomic surveillance