Needle-free drug delivery using shock wave techniques

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006."June 2006."Includes bibliographical references (leaves 93-94).A recent advancement in the area of needle-free injection systems has been the development of devices capable of epidermal delivery of powder medications. These devices use high-pressure compressed gas to accelerate drug particles 2 to 50 gpm in size to velocities of 200 to 1000 m/s. At these speeds the particles have sufficient momentum to penetrate the skin barrier and reach the viable epidermal layers. The devices offer much better control over the depth of penetration than traditional hypodermic needles, a factor particularly important in vaccine delivery. However they still have not found wide spread use, because of their cost. We studied the parameters determining the performance of these devices and used that knowledge to create a simple and reusable device capable of delivering 3 to 10 mg of powder formulation to the viable epidermis. Furthermore we showed that hydrogen-oxygen combustion could be used to create the shock wave required to accelerate the drug particles. This proves that portable reusable devices powered by hydrogen can be constructed and used for vaccine and medication delivery.by Atanas Pavlov.S.M

Electro discharge machining for micro manufacturing

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro tools, micro components and parts with micro features. However, a number of issues remain to be solved before micro EDM can become a reliable process with repeatable results and its full capabilities as a micro manufacturing technology can be realised. This work presents some developments in advancing the state-of-the-art in the micro EDM process. EDM drilling and EDM milling are regarded as separate processes as they require different approaches in investigating and implementing the results of the study. At the beginning, special attention is paid to factors and procedures influencing the accuracy achievable, including positioning approaches during EDM and electrode grinding. In particular, the main parameters affecting the size and position of a machined feature are discussed and new techniques for minimising errors are proposed. The technological capabilities of different methods of setting up and dressing the electrode on the machine are analysed. Factors contributing to electrode wear, the main systematic cause for inaccuracy of the dimensions achieved, during the micro EDM process are studied. A method for calculating the volumetric wear ratio based only on geometrical information obtained from the process is proposed. This study investigates the suitability of micro EDM electrode wear compensation methods. Electrode shape deformation and random variations in the volumetric wear are also investigated as the two main factors affecting the applicability of the wear compensation methods as well as indicating the accuracy achievable with micro EDM. When producing features and parts on the micro scale, the phenomena that take place between the electrodes in EDM is not fully understood. A barrier to a complete exploitation of the potential natural tolerance of this process and to the further development of the process towards the production of components on the nano-scale is therefore in place. An analytical micro EDM model of electrode wear based on electrode shape deformation and wear ratio is suggested, verification of which requires experimental work with pure metals. Electrode-tool wear is studied during the micro EDM process of pure metals and the effect of electrode wear on the process accuracy and process variability. Objectives in this case are to advance the experimental knowledge of the electrical discharges during micro EDM operations which often conflicts with existent theoretical models of the EDM process. In particular, the remit of this investigation is to identify the effects that electrode materials have on selected electrical characteristics of the discharge process. An exploratory data analysis (EDA) approach is adopted in order to draw conclusions from the performed experimental activity. The material removal mechanism in the micro EDM process was confirmed to be mainly attributed to the melting and vaporisation phenomenon. Metal removal takes place as a result of the extremely high temperature generated by the discharge sparks. It was also found in this study that the volumetric wear ratio depends not only on the sparking conditions but also on the electrode materials. In addition, the research also proved that the electrode material severely influences the energy distribution between the electrodes during the sparks.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Electrical measurements in µ-EDM

The phenomena occurring between the electrodes in electric discharge machining when manufacturing features on the micro-metre scale (µ-EDM) is not fully understood. Poor quantitative knowledge of the sources of variability affecting this process hinders the identification of its natural tolerance limits. Moreover, improvements in measuring systems contribute to the acquisition of new information that often conflicts with existent theoretical models of this process. The prime objective of this paper is to advance the experimental knowledge of µ-EDM by providing a measurement framework for the electrical discharges. The effects of the electrodes metallic materials (Ag, Ni, Ti, W) on the electrical measurements defined in the proposed framework are analysed. Linear mixed-effects models are fitted to the experimental data using the restricted maximum likelihood method (REML). The main conclusion drawn is that the discharge current and voltage as defined and measured in this framework do significantly depend on the electrode material even when keeping all the other machining conditions unchanged

Liquid-based cytology and its practicability in Bulgaria

PURPOSE: Our aim was to summarize the foreign and our own experience in screening the cervical cancer by using conventional Papanicolaou (PAP) smear and liquid-based cytology (LBC).MATERIAL AND METHODS: In the Department of Obstetrics and Gynecology, Medical University of Varna, we examined 100 patients and compared the results from LBC with those from conventional PAP smear concerning different criteria as well as to test LBC practicability in Bulgaria.RESULTS: There were significant advantages of LBC mainly due to the lower number of unsatisfactory results and higher specificity of low-grade squamous intraepithelial lesions (LSIL). The comparison with the results from foreign studies demonstrated the same tendencies and diagnostic values.CONCLUSION: Our investigation proved the benefits of LBC in screening the cervical cancer. A much broader application of this method in Bulgaria was recommended taking into consideration that it was rarely used at presence.Scripta Scientifica Medica 2013; 45(2): 66-69

Electro discharge machining for micro manufacturing

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro tools, micro components and parts with micro features. However, a number of issues remain to be solved before micro EDM can become a reliable process with repeatable results and its full capabilities as a micro manufacturing technology can be realised. This work presents some developments in advancing the state-of-the-art in the micro EDM process. EDM drilling and EDM milling are regarded as separate processes as they require different approaches in investigating and implementing the results of the study. At the beginning, special attention is paid to factors and procedures influencing the accuracy achievable, including positioning approaches during EDM and electrode grinding. In particular, the main parameters affecting the size and position of a machined feature are discussed and new techniques for minimising errors are proposed. The technological capabilities of different methods of setting up and dressing the electrode on the machine are analysed. Factors contributing to electrode wear, the main systematic cause for inaccuracy of the dimensions achieved, during the micro EDM process are studied. A method for calculating the volumetric wear ratio based only on geometrical information obtained from the process is proposed. This study investigates the suitability of micro EDM electrode wear compensation methods. Electrode shape deformation and random variations in the volumetric wear are also investigated as the two main factors affecting the applicability of the wear compensation methods as well as indicating the accuracy achievable with micro EDM. When producing features and parts on the micro scale, the phenomena that take place between the electrodes in EDM is not fully understood. A barrier to a complete exploitation of the potential natural tolerance of this process and to the further development of the process towards the production of components on the nano-scale is therefore in place. An analytical micro EDM model of electrode wear based on electrode shape deformation and wear ratio is suggested, verification of which requires experimental work with pure metals. Electrode-tool wear is studied during the micro EDM process of pure metals and the effect of electrode wear on the process accuracy and process variability. Objectives in this case are to advance the experimental knowledge of the electrical discharges during micro EDM operations which often conflicts with existent theoretical models of the EDM process. In particular, the remit of this investigation is to identify the effects that electrode materials have on selected electrical characteristics of the discharge process. An exploratory data analysis (EDA) approach is adopted in order to draw conclusions from the performed experimental activity. The material removal mechanism in the micro EDM process was confirmed to be mainly attributed to the melting and vaporisation phenomenon. Metal removal takes place as a result of the extremely high temperature generated by the discharge sparks. It was also found in this study that the volumetric wear ratio depends not only on the sparking conditions but also on the electrode materials. In addition, the research also proved that the electrode material severely influences the energy distribution between the electrodes during the sparks

Manufacturing Lead-Time Reduction and Knowledge Sharing in the Manufacturing Sector

Abstract: At this time, companies' need to improve their manufacturing competitiveness in terms of better, faster and cheaper products has led to a range of approaches including 'just in time'; lead-time reduction; lean manufacture; using social networks; and knowledge sharing, in order to be first to get products and services to customers faster. Companies seek to reduce manufacturing lead-time (MLT) in order to reduce the cost of production; short lead-times are a major source of potential competitive advantage. This paper proposes a study on reducing MLT in factories in the Kurdistan region of Iraq, where lead-time has become a major issue for the manufacturing industry. The aim is to provide guidance to industry practitioners and technicians on how to reduce MLT. The paper will present a conceptual framework of the causes and will use knowledge-sharing sources such as social media to survey the factors that have significant impact on lead-time. It will also describe the relationship between setup time, operation time, and non-operation time in order to find potential methodologies that can reduce lead-time in the manufacturing process and identify simple strategies for reducing lead-time

Metastatic colorectacal carcinoma, associated with pyogenic liver abscess

Introduction: A liver abscess represents capsulated purulent focus in the liver parenchyma, due to bacterial, fungal or parasite invasion. In the recent years their frequency rate related to malignant diseases has increased, including abscesses in liver metastases. Aim: We present four cases of metastatic colorectacal carcinoma, associated with pyogenic liver abscess, which were treated in the Second Department of Surgery, St. Marina University Hospital, Varna.Results:  We registered synchronous metastases and in two patients and the remaining two had metachronous metastases. The average age of our patients was 60 years (range 45-80). The patients were operated on and the following interventions were performed – in one - segmentectomy; in two - liver resection with right hemicolectomy; in one - incision, biopsy and drainage; and in one – percutaneous drainage. We established the following systemic complications: pleural effusion in one patient, in one – arrhythmia, subphrenic abscess – in two patients.  The bacterial strains showed K. pneumoniae  in one patient, two – sterile and in one S. epidermidis.Discussion:  In the recent years a lasting tendency of increasing of the frequency rate of malignant diseases of the GIT has been observed.  The liver abscesses complicating a malignant disease can be treated like an abscess due to benign pathology – via aspiration, drainage and antimicrobial therapy.  Surgical treatment is applied in larger (more than 5 cm) abscesses or with colorectal cancer. The prognosis in these cases is unfavorable due to the malignant diseases and the higher frequency rate of the septic complications

How different strains of COVID-19 affect LUTS in BPH patients?

In late 2019, an outbreak of pneumonia of unknown etiology was reported in Wuhan (China). The causative agent was quickly identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the impact of COVID-19 (coronavirus disease 2019) on various organs and symptoms has been studied, there is still a dearth of data regarding its effect on the genitourinary system. In this study, we investigated the impact of different COVID-19 strains on lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH). A total of 69 patients who had previously been infected with COVID-19 from August 2021 to October 2021 and January 2022 to May 2022 were assessed. The two periods were purposively selected based on the dominant COVID-19 variant: the Delta strain for the first period and Omicron for the second, respectively. All patients had BPH and were followed up in two outpatient practices. Demographic information was collected, and LUTS were assessed using the international prostate symptom score (IPSS) questionnaires before and after COVID-19. Ultrasound examinations were performed to determine the prostate gland volume and the post-voided residual (PVR) in each patient. All patients affected by COVID-19 exhibited a worsening of LUTS. The degree of deterioration differed between those infected with different COVID-19 strains. Patients infected with the Delta strain had more severe LUTS than those with the Omicron strain. There is currently limited information available regarding the emerging pathophysiological processes in the urogenital system related to COVID-19. This present study serves as a preliminary investigation into the impact of COVID-19 on LUTS in BPH patients and could serve as a basis for more extensive multicenter studies leading to fundamental discoveries

Laparoscopic or conventional abdominoperineal extirpation in low rectal cancer

INTRODUCTION: Laparoscopic abdominoperineal resection (LAPR) as a minimally invasive approach for the treatment of large rectal cancer is widely used. It has been proven to be technically feasible and safe with fewer complications and faster postoperative recovery than the open procedure. Our aim was to evaluate LAPR safety and feasibility as compared to the open procedure in large low rectal cancer.PATIENTS AND METHODS: A total of 34 low rectal cancer patients who underwent open APR (OAPR) were matched with 42 patients who underwent LAPR in a one-to-one fashion between 2011 and 2014 in the Divi­sion of General Surgery, Kaspela University Hospital of Plovdiv.RESULTS: Intraoperative parameters of LAPR were better than those of OAPR as followed: mean operation time (121.8±47.8 min versus 152.1±49.2 min), mean operative blood loss (82±30.0 mL versus 120±35.0 mL), mean total number of retrieved lymph nodes (12±1 versus 12±1.4), and percentage of surgical complications (12.3% versus 15.1%). Laparoscopically treated patients showed significantly shorter postoperative analge­sia (2.1±0.7 days versus 3.7±0.6 days), earlier first flatus (36.3±7.9 hours versus 48.5±9.2 hours), shorter uri­nary drainage (3.8±3.4 days versus 5.8±1.3 days), and shorter hospital stay (6.2±1 days versus 8±2.0 days). Local recurrence rate during a three-year period (in 3 versus 4 patients) and metachronous liver metastasis (in 5 versus 6 patients) were less common after LAPR than after OAPR.CONCLUSION: The risks of APR-specific surgical complications such as perineal wound infection and para­stomal hernia were comparable between the laparoscopic and open surgery groups. There were no signifi­cant differences regarding local recurrence and metachronous liver metastasis between these groups. Com­plication and locoregional recurrence rates in low large rectal cancer patients after laparoscopic and open were quite similar. Scr Sci Med 2017; 49(3): 22-2