Micromechanical properties of demineralized dentin collagen with and without adhesive infiltration

In a previous study, we reported the upper limit of Young's modulus of the unprotected protein at the dentin/adhesive interface to be 2 GPa. In this study, to obtain a more exact value of the moduli of the components at the d/a interface, we used demineralized dentin collagen with and without adhesive infiltration. The prepared samples were analyzed using micro-Raman spectroscopy (micro RS) and scanning acoustic microscopy (SAM). Using an Olympus UH3 SAM (Olympus Co., Tokyo), measurements were recorded with a 400 MHz burst mode lens (120 degrees aperture angle; nominal lateral resolution, 2.5 microm). A series of calibration curves were prepared using the relationship between the ultrasonically measured elastic moduli of a set of known materials and their SAM response. Finally, both the bulk and bar wave elastic moduli were computed for a set of 13 materials, including polymers, ceramics, and metals. These provided the rationale for using extensional wave measurements of the elastic moduli as the basis for extrapolation of the 400 MHz SAM data to obtain Young's moduli for the samples: E = 1.76 +/- 0.00 GPa for the collagen alone; E = 1.84 +/- 0.65 GPa for the collagen infiltrated with adhesive; E = 3.4 +/- 1.00 GPa for the adhesive infiltrate.     

A Review on Synthetic Fibers for Polymer Matrix Composites: Performance,Failure Modes and Applications

In the last decade, synthetic fiber, as a reinforcing specialist, has been mainly used in polymer matrix composites (PMC’s) to provide lightweight materials with improved stiffness, modulus, and strength. The significant feature of PMC’s is their reinforcement. The main role of the reinforcement is to withstand the load applied to the composite. However, in order to fulfill its purpose, the reinforcements must meet some basic criteria such as: being compatible with the matrix, making chemical or adhesion bonds with the matrix, having properties superior to the matrix, presenting the optimal orientation in composite and, also, having a suitable shape. The current review reveals a detailed study of the current progress of synthetic fibers in a variety of reinforced composites. The main properties, failure modes, and applications of composites based on synthetic fibers are detailed both according to the mentioned criteria and according to their types (organic or inorganic fibers). In addition, the choice of classifications, applications, and properties of synthetic fibers is largely based on their physical and mechanical characteristics, as well as on the synthesis process. Finally, some future research directions and challenges are highlighted.     

Isolated Double Gastric Perforation in Blunt Abdominal Trauma—a Case Report

Blunt abdominal trauma mostly results from motor vehicle accidents, recreational accidents, falls or assaults with commonly injured internal organs being the spleen, liver, retroperitoneum, small bowel, kidneys, bladder, colorectal, diaphragm and pancreas. Gastric rupture is quite uncommon. Isolated gastric perforations following blunt trauma to the abdomen are mostly seen in paediatric patients. It is uncommon in adult patients and even rarer is the occurrence of double gastric perforations. We report here with a case of isolated double gastric perforation in a 24-year-old male patient following vehicular accident.     

Microbial life at ?13 °C in the brine of an ice-sealed Antarctic lake

The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (−13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H₂), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L⁻¹ nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans.     

Tissue expansion: Concepts,techniques and unfavourable results

The phenomenon of tissue expansion is observed in nature all the time. The same properties of the human skin to stretch and expand and yield extra skin if placed under continuous stress over a prolonged period of time has been utilised for reconstructive purposes with the help of a silicon balloon inserted under the skin and progressively filled with saline. The technique of tissue expansion is now more than three decades old and has been a value addition to our armamentarium in reconstructive surgery in all parts of the body. However, it still requires careful patient selection, meticulous planning and faultless execution to successfully carry out the process, which usually lasts for more than 8-12 weeks and involves two sittings of surgery. Any compromise in this process can lead to unfavourable results and complications, some minor, which allow continuance of the process to attain the expected goal and others major, which force abandonment of the process without reaching the expected goal. This article seeks to highlight the intricacies of the concept of tissue expansion, the technique related to flawless execution of the process and likely complications with emphasis on their management. We also present our results from a personal series of 138 patients operated over a period of 18 years between 1994 and 2012.KEY WORDS: Complications, tissue expansion, unfavourable results     

Desmethyl Macrolides: Synthesis and Evaluation of 4-Desmethyl Telithromycin

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Laparoscopic total radical hysterectomy by the Pune technique: our experience of 248 cases

STUDY OBJECTIVE: To describe our experience and technique of total laparoscopic radical hysterectomy with pelvic lymphadenectomy, which is the largest single- institution study. DESIGN: Retrospective, nonrandomized study (Canadian Task Force classification II-2). SETTING: Private hospital. PATIENTS: Two hundred forty-eight patients with International Federation of Gynecology and Obstetrics stage IA2 (n = 32) and IB1 (n = 216) of cancer of the cervix. INTERVENTION: Total laparoscopic type III radical hysterectomy with bilateral pelvic lymphadenectomy was done. Simple repetitive steps were used to perform this surgery and develop an easily replicable technique. Harmonic Shears, bipolar coagulation, and vascular clips were used. Resection of the cardinal and uterosacral ligaments was performed with LigaSure (LigaSure Vessel Sealing System; Valleylab, Tyco Healthcare, Boulder, CO) or the Harmonic Shears (Ethicon Endo-Surgery, Inc., Cincinnati, OH). Pelvic lymph node dissection was done. MEASUREMENTS AND MAIN RESULTS: Histopathologically, there were 183 (73%) cases of squamous carcinoma, 52 (20%) adenocarcinomas, and 13 (5%) adenosquamous carcinomas. Four patients needing anterior exenteration because of bladder involvement were excluded from data analyses. The operation was performed entirely by laparoscopy in all patients and by the same surgical team. The patients' median age was 61 years. The median operative time was 92 minutes (range 65-120 minutes). The median number of resected pelvic nodes was 18. The median blood loss was 165 mL. The median length of stay was 3 days. All 15 intraoperative complications were tackled laparoscopically. No patients were converted to the open technique. There were no deaths in our series. Seventeen patients had complications within 2 months of surgery. Seven patients had recurrences after a median follow-up of 36 months. CONCLUSION: Our technique of total laparoscopic radical hysterectomy, developed over 248 cases, can be performed safely. It is an easily replicable technique. This procedure reduces the morbidity associated with abdominal radical hysterectomy. All of the complications can also be tackled laparoscopically, which does not further add to the morbidity.