Recycling E-Waste for Sustainable Management of Natural Resources

Electronic waste (E-waste) which consists of old, end-of life, discarded electrical and electronic equipment’s (EEE), is the most rapidly growing MSW stream worldwide. The toxic and hazardous materials present in it can lead to severe environmental and occupational hazards, if not handled properly. However, presence of significant quantity of valuable recoverable material makes it a potential secondary resource for metal extraction. Composition of E-waste is complex with 38% ferrous material, 28% non-ferrous material, 19% plastic, 4% glass, 11% other (wood, rubber, ceramic, etc.). Although the precious materials are only 1% by weight, it accounts to nearly 80% of the total intrinsic value. Around $ 21 billion of Au and Ag are used in various EEE per annum.Along with precious metals it also contains various rare earth metals such as Platinum, Gallium, Indium, Lithium, etc. Primary metal extraction from mining has significant negative environmental impact due to substantial natural resources consumed and low recovery efficiency; comparatively extraction from E-waste is 50 times greater which is much more economical with lesser ecological foot printand the energy savings are considerable: aluminium 95%, copper 85%, iron and steel 74%, plastics 80%. This is the reason why E-waste recycling which is also called as “Urban Mining” can facilitate in sustainable management and conservation of rapidly depleting natural resources

Study of Valuable and Hazardous Metals from Capacitors of Personal Computer

Desktop personal computer (PC) is one of the major contributors of the waste electrical and electronic equipment’s (WEEE) generated worldwide. Composition of a typical desktop PC is complex and consists of hundreds of different materials which may be valuable, precious as well as hazardous in nature. Due to globalization and changing economic scenario, huge amount of E-waste is generated and its management has become a challenging task. The present paper highlights the various metals that can be recovered and recycle from the capacitors obtained from the printed circuit boards (PCB) of Central Processing Unit (CPU). Capacitors contain valuable (Aluminum, iron, copper, zinc, magnesium, manganese, nickel, etc.), hazardous (lead, chromium) and precious (silver) metals. The study of capacitors has been broadly undertaken following various systematic steps, which includes study of different types of capacitors present on the PCBs, its quantification, and characterizations studies. Effect of surface area on metal leaching efficiency was studied. It was observed that the electrolytic capacitors are present in higher quantity followed by solid electrolytic capacitors. Most of the valuable and hazardous metals were found in ceramic, film and solid electrolytic capacitors, also the metal leaching rate enhances by increasing surface area

Evaluation of the effect of size reduction and thermal treatment on metal extraction from PCBs of mother board and digital video drive of desktop PC

The study aims at evaluating the effect of particle size and thermal treatment on printed circuit boards (PCBs) of Mother Board (MB) and DVD on metal extraction. Results show around 90–95% (w/w) and 35–40% (w/w) of total Al and Cu respectively, in CPU could be recovered by systematized disassembly. Re-maining embedded Al and Cu require metallurgical or hydro-metallurgical processing. Cu extraction in-creases with size reduction. Thermal treatment of MB–PCB shows reduction in Cu extraction (23–38%) for all sizes in comparison without thermal treatment, while DVD–PCB showed surge in extraction after thermal treatment (41–141%) in comparison without thermal treatment

Esophagectomy without mortality: What can surgeons do?

Introduction: Surgical resection remains the mainstay treatment for patients with localized esophageal cancer. It is, however, a complex procedure. Mortality rate used to be high, but in recent years, death rate has been reduced to below 5% in specialized centers. Methods: Outcome of esophagectomy can be improved by paying attention to (1) appropriate patient section, (2) choice of surgical techniques and their execution, and (3) optimizing perioperative care. A volume-outcome relationship is also evident. Surgeons can perform esophagectomy without mortality, but a multi-disciplinary team management is essential to achieve this goal. © 2009 The Society for Surgery of the Alimentary Tract.postprin

The status of the world's land and marine mammals: diversity, threat, and knowledge

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action

Non-randomness of the anatomical distribution of tumors

Background: Why does a tumor start where it does within an organ? Location is traditionally viewed as a random event, yet the statistics of the location of tumors argues against this being a random occurrence. There are numerous examples including that of breast cancer. More than half of invasive breast cancer tumors start in the upper outer quadrant of the breast near the armpit, even though it is estimated that only 35 to 40% of breast tissue is in this quadrant. This suggests that there is an unknown microenvironmental factor that significantly increases the risk of cancer in a spatial manner and that is not solely due to genes or toxins. We hypothesize that tumors are more prone to form in healthy tissue at microvascular ‘hot spots’ where there is a high local concentration of microvessels providing an increased blood flow that ensures an ample supply of oxygen, nutrients, and receptors for growth factors that promote the generation of new blood vessels. Results: To show the plausibility of our hypothesis, we calculated the fractional probability that there is at least one microvascular hot spot in each region of the breast assuming a Poisson distribution of microvessels in two-dimensional cross sections of breast tissue. We modulated the microvessel density in various regions of the breast according to the total hemoglobin concentration measured by near infrared diffuse optical spectroscopy in different regions of the breast. Defining a hot spot to be a circle of radius 200 μm with at least 5 microvessels, and using a previously measured mean microvessel density of 1 microvessel/mm2, we find good agreement of the fractional probability of at least one hot spot in different regions of the breast with the observed invasive tumor occurrence. However, there is no reason to believe that the microvascular distribution obeys a Poisson distribution. Conclusions: The spatial location of a tumor in an organ is not entirely random, indicating an unknown risk factor. Much work needs to be done to understand why a tumor occurs where it does. Electronic supplementary material The online version of this article (10.1186/s41236-017-0006-7) contains supplementary material, which is available to authorized users

Letter to the Editor - Codman's Triangle in Tubercular Osteomyelitis

Sir, An eight-year-old male child presented with prolonged history of low-grade fever and a progressively increasing swelling on left lower thigh. His grandmother was treated for pulmonary tuberculosis a year back. He had cervical lymphadenopathy, hepatosplenomegaly and bronchial breath sounds and crepitations in right infra-axillary area. The thigh swelling was firm, mobile and tender without erythema or warmth. The movements of the left knee joint were normal. Investigations showed haemoglobin concentration of 7.6gm%, total leucocyte count of 6200/mm3 with polymorphs 73%, lymphocytes 26%, and eosinophils 1%. Erythrocyte sedimentation rate was 125 mm at the end of one hour. Tuberculin test produced 15x20 mm induration. Chest X-ray showed right middle and lower zone consolidation with mediastinal enlargement. ELISA for retrovirus was negative. X-ray of lower end of left femur (Figure) showed anterolateral cortical erosion with subperiosteal new bone formation in the form of Codman's triangle. Medullary bone sclerosis was also seen. Excisional biopsy of swelling revealed epitheloid cell granuloma, caseous necrosis and new bone formation. Stain for acid-fast bacilli were positive and culture grew tubercle bacilli. He was started on anti-tubercular treatment, to which he has clinically responded