Quantum Dots: Synthesis, Characterization and electrochemical sensing for life sciences

Subjects of the present dissertation are the synthesis, and the characterization of colloidal Quantum dots and their application in electrochemical biosensors for biological and life sciences. This study splits into two parts. The first part consists on the synthesis and the characterization of various types of quantum dots (QDs), i.e., doped (CdS:Mn and CdS/Mn:ZnS/ZnS core/shell) and undoped (CdS, CdS/ZnS core/shell, CdSe and CdSe/ZnS core/shell QDs) QDs. The second part concerns the fabrication of a bioelectrochemical sensor based on CdS/ZnS QDs. Mn-doped CdS and CdS/ZnS QDs were synthesized in organic solvent; Mn ions were incorporated into CdS QDs (CdS:Mn) and in the case of the CdS/ZnS QDs, Mn ions were incorporated into a thin (2 atomic monolayers) ZnS shell, which after Mn doping was further grown (2 atomic monolayers). In order to study the optical properties of Mn doped CdS/ZnS core shell QDs, a fluorescence resonance energy transfer (FRET) system was performed, in which the Mn2+ ions and organic dyes(ATTO633) as acceptors were incorporated into the ZnS shell and polymer shell, respectively. The polymer shell was used to provide colloidal stability for the CdS/ZnS QDs. In this study, we propose that the double energy transfer process take place among the three fluorescence sources, first within the Mn-doped CdS/ZnS QDs, i.e., from the CdS/ZnS QDs to the Mn ions and then, from the excited Mn ions to the organic dye, the organic fluorophore ATTO633 incorporated within the polymer coating of Mn-doped CdS/ZnS QDs. A bioelectrochemical sensor for specific detection of guanosine monophosphate (GMP) is demonstrated based on the combination of three enzymatic reactions. We have combined all three enzymatic reactions with the detection at the QD electrode. In both cases, all three enzymes (i.e., Guanylate monophosphate kinase (GMPK), pyruvate kinase (PK) and lactate dehydrogenase (LDH)) were immobilized together, on top of the QD electrodes, or added directly to the electrolyte solution. Photocurrent measurements were performed with varying concentrations of GMP, but with fixed concentration of the three enzymes and other enzymes /coenzymes like adenosine triphosphate (ATP), phosphoenolpyruvat (PEP), and nicotinamide adenine dinucleotide hydrogen NADH. Clearly the photocurrent response was found to be dependent on the GMP concentration added to the solution. This verifies that a signal cascade from the first GMPK reaction through the PK and LDH reaction, and finally to the NADH to NAD+ oxidation at the QD electrode could be measured. In the first reaction, the enzymatic conversion of GMP by GMPK produces adenosine diphosphate(ADP). In the second reaction, ADP and phosphoenolpyruvate (PEP) are converted into Adenosine triphosphate (ATP) and pyruvate. In the third reaction pyruvate (Py) and nicotinamide adenine dinucleotide hydrogen (NADH) are converted to lactate and nicotinamide adenine dinucleotide (NAD+). Finally Py was converted by LDH under consumption of NADH, which was electrochemically determined. The photocurrent response to GMP for the combined reaction demonstrates that GMP could be detected electrochemically

Perception about Health and Disease

Background: To assess peoples’ general concepts about health and disease and basis of disease occurrence in man in an objective way. Methods: It was an observational descriptive study. Perceptions of the attendants (n=110) of the patients who approached a public sector tertiary care hospital in Rawalpindi were assessed through a questionnaire by interviewer-administered technique. Their concepts about health and disease were explored by open-ended questions and their understanding of ways of disease causation evaluated six sets of closed ended options. Results: Of the total study participants (n=110), with mean age 36 Years, 58% were males and 42% were females. Majority were married (71%) , of lower economic status (45%), and rural area (70%). Education in 51% was above 10years of schooling. In 36% subjects concept of health and in 25% concept of disease was scientifically appropriate at their level. On average 66.3% of the respondents had concept of scientific basis of disease. causation while 33.6% did not hold scientifically sound concepts. In set-IV majority believed in that disease may result as punishment from God but this belief was significantly high in females (X2cal= 8.1, P<0.005). Conclusion: Though people understandings in matter of health are not optimum but it is promising within their socioeconomic capacity. Efforts are needed to promote health literacy among masses beyond the conventional mode. Care providers should respect their beliefs while interacting with patients

Clinico- haematological spectrum of females with inherited Bleeding Disorders

Background: Inherited bleeding disorders in females are under-diagnosed, eventually leading to multiple problems. This situation is further worsened by the inadequate information , non – availability of diagnostic facilities and low awareness on the clinical side Methods: In this non – interventional descriptive study , females with inherited bleeding disorders were assessed. Clinical presentations, demographic data and management received was recorded. Complete blood counts, prothrombin time, activated partial thromboplastin time, thrombin time and platelet function studies were performed, where required.. Results: In all the patients with inherited bleeding disorders , females constituted 16.85%. von Willebrand disease was the commonest (50.84%) out of all inherited bleeding disorders in females. In rest of the females autosomal recessive coagulation defects and platelet function defects constituted 25.42% and 23.72%, respectively. Majority of the females (83.04%) were below 17 years of age. Menorrhagia (46.87%) was the commonest clinical episode. Spontaneous bleed was seen in 95% episodes. Majority of the episodes (94.14%) were soft tissue bleeding episodes and joint bleeds were minimal (5.68%). Tranexamic acid was the most commonly used therapeutic agent . Surgical intervention was employed in 18 episodes. Conclusion: Females with inherited bleeding disorders have severely impaired quality of life , fail to get proper management and go through unwanted surgeries ( D&C; Hysterectomies)

Does Corporate Entrepreneurship matter for Organizational Learning Capability? A Study on Textile Sector in Pakistan

The paper aims to investigate the relationship between corporate entrepreneurship and organizationallearning capability. A survey method was undertaken to collect data from 240 middle level managersworking in textile industry through convenience sampling method. Results indicate a positive andsignificant relationship between variables. Practical implications of the study are that if any organizationwhich tends to be more innovative and risk taking has the more learning capability. Furthermore,entrepreneurship training programs could lead to enhancing competences which are important forentrepreneurship.Key Words: Corporate entrepreneurship, Organizational Learning Capability, Textile Sector, Pakistan

Contamination of Water Resources by Food Dyes and Its Removal Technologies

Food dyes comprise different groups which impart color to a wide range of food products. Food products are mainly purchased and consumed by people because they are nutritive and flavorsome and have an attractive color. Food color stimulates appetite and enhances its esthetic appeal of food on table for customer. With sky rocketing industrialization and modernization, the worldwide production of dyes in 2010 was forecasted to be 2.1 metric tons. It has been estimated that 15% of total dyes produced worldwide are discharged to water bodies which adversely affect aquatic ecosystem. Dyes in water reduces its transparency, thereby declining light penetration in the water, hence influencing photosynthesis which consequently reduces dissolved oxygen which is an alarming situation for both aquatic flora and fauna. Dyes wastewater discharged from huge number of industries like textile, leathers, paint, food, pharmaceutical etc. and deteriorating the aquatic environment and pose threat to living organism. The presence of dye molecules in water channels is an emerging alarm to an environmental scientist. An environmental friendly and self-sustainable treatment method should be explored to address this problem. Therefore, this work elaborates the various methods used for removal and degradation of dyes in water, although some processes have a common shortcoming like production of secondary pollution to the environment. This chapter have tried to highlight the important application of food dyes, their contamination and their toxic effect. Herein we also focus on remediation techniques like separation (adsorption, filtration, etc.) and degradation (chemical, biological and electrochemical oxidation) of dyes in aqueous solution. The mechanism and pros and cons of different methods are explored and discussed briefly

Nanodiagnosis and Nanotreatment of Cardiovascular Diseases: An Overview

Cardiovascular diseases (CVDs) are the world’s leading cause of mortality and represent a large contributor to the costs of medical care. Although tremendous progress has been made for the diagnosis of CVDs, there is an important need for more effective early diagnosis and the design of novel diagnostic methods. The diagnosis of CVDs generally relies on signs and symptoms depending on molecular imaging (MI) or on CVD-associated biomarkers. For early-stage CVDs, however, the reliability, specificity, and accuracy of the analysis is still problematic. Because of their unique chemical and physical properties, nanomaterial systems have been recognized as potential candidates to enhance the functional use of diagnostic instruments. Nanomaterials such as gold nanoparticles, carbon nanotubes, quantum dots, lipids, and polymeric nanoparticles represent novel sources to target CVDs. The special properties of nanomaterials including surface energy and topographies actively enhance the cellular response within CVDs. The availability of newly advanced techniques in nanomaterial science opens new avenues for the targeting of CVDs. The successful application of nanomaterials for CVDs needs a detailed understanding of both the disease and targeting moieties

Assessment of thermo-hydraulic performance of inward dimpled tubes with variation in angular orientations

This paper presents a numerical investigation and assessment of thermal and hydraulic performance of dimpled tubes of varying topologies at constant heat flux of and Reynolds numbers ranging from 2300 to 15,000 The performance of the tubes consisting of conical, spherical and ellipsoidal dimples with equivalent flow volumes were compared using steady state Reynolds Averaged Navier Stokes simulations. The ellipsoidal dimples, in comparison to other dimple shapes, demonstrated large increment in heat transfer rate. The variation in the orientation of the ellipsoidal dimples was examined to further improve thermal and hydraulic performances of the tube. A 45° inclination angle of ellipsoidal dimple, from its major axis, increased the thermo-hydraulic performance by 58.1% and 20.2% in comparison to smooth tube and 0° ellipsoidal dimpled tube, respectively. Furthermore, Large Eddy Simulations (LES) were carried out to investigate the role geometrical assistance to fluid flow and heat transfer enhancement for the 45° and 90° ellipsoidal dimpled tubes. LES results revealed a flow channel of connected zones of wakes which maximized fluid-surface

Thermoelectric Properties of Oxide Semiconductors

In this chapter, we have explored the potential of oxide semiconductors for thermoelectric power generation. Various oxides (Cu2InO4, CuAlO2, and Zn2GeO4) were grown on Si substrate by thermal evaporation method using tube furnace. After the growth, a representative sample of each oxide was cut into pieces and was annealed at various temperatures from 600 to 800°C in oxygen environment for 1 h using a programmable furnace. The structure of all annealed sample was verified by performing X-ray powder diffraction (XRD) measurements. XRD data suggested that all oxide materials show crystalline behavior at annealing temperature 800°C. XRD results further confirmed that crystal structure of investigated samples improved significantly with annealing because the intensity of oxygen-sensitive (0 0 6) plane was found to be increased with annealing temperature. To investigate the thermoelectric properties of annealed samples, Seebeck effect and Hall effect measurements were performed in the temperature range 25–100°C. It was found that the value of Seebeck coefficient and power factor increased as the annealing temperature increases. Zn2GeO4 was found to be a potential thermoelectric material because it has the highest value of Seebeck coefficient and power factor. This highest value is related to the presence of secondary phases in this oxide

Human Cryptosporidiosis: An insight into Epidemiology, Modern Diagnostic Tools and Recent Drug Discoveries

Cryptosporidiosis is an emerging food and water borne zoonotic disease, which is caused by genusCryptosporidium. The first Cryptosporidium spp. was isolated from mice in 1907 and gained importance when it was found in an HIV positive patient. It usually causes self-limiting diarrhea in young children and immunocompetent patients. However, it may lead to chronic diarrhea with life threatening condition in immunocompromised patients. Other complications related to this transmittable infection may include respiratory problems, skin rashes and headache. HIV/AIDS patients are highly susceptible host for this parasite. Cryptosporidium parvum and Cryptosporidium hominis are the known pathogenic species, prevalent among humans and they are being transmitted through contaminated food and water. Usually, the diagnosis of Cryptosporidium spp. is dependent on microscopic technique in many countries, which has a low sensitivity and specificity leading to false positive results. However, for a step forward to successful epidemiological studies, advanced techniques (Serological and DNA-based) provide us the better ways of diagnosis with more sensitivity and specificity. Furthermore, no antiparasitic drug has found to be effective againstCryptosporidium spp. except Nitazoxanide which is FDA-approved and effective only when administered along with antiretroviral therapy. In this regard, present review summarizes the various epidemiological studies conducted around the globe along with modern diagnostic tools and the suitable treatment available now a days. This systemized review will help the scientists to better understand all the aspects of cryptosporidiosis at one platform which may help in designing surveillance studies through selection of sensitive diagnostic techniques. The new drugs mentioned in this review may also help to better control this parasite in humans, especially immunocompromised individuals