Polybenzoxazine aerogels: synthesis, characterization, conversion to porous carbons, and energetic composites

Aerogels are nanoporous, low-density bulk objects, consisting of three-dimensional assemblies of nanoparticle. Structured similarly, polymeric aerogels are emerging as a mechanically strong alternative to traditional silica aerogels, which are fragile. Amongst polymeric aerogels, those based on polybenzoxazine (PBO - a type of phenolic resin), are extremely robust and comprise an economic alternative to resorcinol-formaldehyde aerogels, also a class of phenolic resins, as the main source of carbon aerogels. The drawback of the PBO chemistry has been the long (days) processing time at high-temperatures (\u3e130 ºC). Herewith, we have developed an energy- and time-efficient process to PBO aerogels by inducing acid-catalyzed gelation at room-temperature completed in a few hours. The new aerogels are compared directly with their conventional counterparts and are found equivalent or better in terms of mechanical strength, thermal insulation value, surface area and carbonization yield. Hexahydrated iron chloride (FeCl₃.6H₂O) is a fairly strong Bronsted acid, which, based on the above, catalyzes formation interpenetrating networks of PBO and iron oxide nanoparticles (PBO-FeOx). Pyrolysis of that intimate mixture of a carbon source (PBO) and iron oxide undergoes smelting to highly porous (\u3e90% v/v) monolithic metallic iron aerogels. The porous network was loaded with oxidizers (e.g., LiClO₄) into a new class of energetic materials (thermites, explosives, pyrotechnics). The PBO aerogels developed here comprise a wide-base platform for use as thermal insulators in civil and transportation applications (PBO aerogels themselves), electrodes for fuel cells, lithium ion batteries (nanoporous carbons), catalysts and energetic materials (PBO-FeOx) --Abstract, page v

Ballista – ein Traum von Alexander

Robots and machine are taking over a lot of manual work, earlier done by men, and making it better by being not only quicker in doing the same task, but also in a much more This was the main aim of our project as we tried to engineer a efficient way. This paper is heavily based on the Ballista (Catapult) used by many great rulers including Alexander the Great in a bid to win wars. It is an engineering marvel built to launch projectiles across great distances inflicting quite some damage. Depending on the needs, a catapult can be modified and used to destroy or create an opening in mountain ranges or just simply as a war weapon. We have created a miniature, albeit working prototype of the same using the Lego Mindstorms NXT kit and programming of the same using MATLAB.Robots and machine are taking over a lot of manual work, earlier done by men, and making it better by being not only quicker in doing the same task, but also in a much more This was the main aim of our project as we tried to engineer a efficient way. This paper is heavily based on the Ballista (Catapult) used by many great rulers including Alexander the Great in a bid to win wars. It is an engineering marvel built to launch projectiles across great distances inflicting quite some damage. Depending on the needs, a catapult can be modified and used to destroy or create an opening in mountain ranges or just simply as a war weapon. We have created a miniature, albeit working prototype of the same using the Lego Mindstorms NXT kit and programming of the same using MATLAB

Chitosan mediated nanoparticles from Saccharomyces cerevisiae and its Mosquito Larvicidal Activity

Mosquitoes are one of the most medically significant groups of vectors, having an ability to transmit parasites and pathogens that can have devastating impacts on humans. In this study, chitosan nanoparticles were synthesized from chitosan polymer by ionic gelation method. The chitin was first extracted from Saccharomyces cerevisiae and then deacetylated to chitosan. Silver nanopartcals were also prepared and the presence and characterization was investigated by scanning electron microscopy (SEM). The comparative study of the larvicidal activity of chitosan nanoparticles and silvers was also studied which shows chitosan nanoparticles started  mortality at higher concentrations, it showed uniform rise in mortality of mosquito larvae than silver nanoparticles.

Purple urine bag syndrome: an unusual clinical presentation

Purple Urine Bag Syndrome (PUBS) is a rare presentation of urinary tract infection caused by certain bacteria that produce sulphatases and phosphatases that bring about metabolism of tryptophan, leading to production of pigments indigo and indirubin that together impart purple colour of urine. It is a benign condition, most often associated with long term urinary catheterization, renal diseases, chronic constipation and female gender. Commonly implicated organisms include Proteus mirabilis, Klebsiella pneumoniae, Providencia stuartii. Diagnosis is made on urinary culture. Treatment includes reassurance and antibiotics for UTI. We present a case of purple urinary bag syndrome in a female patient of carcinoma stomach presenting with gastric outlet obstruction

TOM-1/tomosyn acts with the UNC-6/netrin receptor UNC-5 to inhibit growth cone protrusion in Caenorhabditis elegans

In the polarity/protrusion model of growth cone repulsion from UNC-6/netrin, UNC-6 first polarizes the growth cone of the VD motor neuron axon via the UNC-5 receptor, and then regulates protrusion asymmetrically across the growth cone based on this polarity. UNC-6 stimulates protrusion dorsally through the UNC-40/DCC receptor, and inhibits protrusion ventrally through UNC-5, resulting in net dorsal growth. Previous studies showed that UNC-5 inhibits growth cone protrusion via the flavin monooxygenases and potential destabilization of F-actin, and via UNC-33/CRMP and restriction of microtubule plus-end entry into the growth cone. We show that UNC-5 inhibits protrusion through a third mechanism involving TOM-1/tomosyn. A short isoform of TOM-1 inhibited protrusion downstream of UNC-5, and a long isoform had a pro-protrusive role. TOM-1/tomosyn inhibits formation of the SNARE complex. We show that UNC-64/syntaxin is required for growth cone protrusion, consistent with a role of TOM-1 in inhibiting vesicle fusion. Our results are consistent with a model whereby UNC-5 utilizes TOM-1 to inhibit vesicle fusion, resulting in inhibited growth cone protrusion, possibly by preventing the growth cone plasma membrane addition required for protrusion

Study of validity of risk of malignancy index in perimenopausal women with ovarian mass in a tertiary care hospital in India

Background: Ovarian carcinoma is a silent killer because it presents in advanced stage. In India, it ranks third after carcinoma cervix and breast. Incidence of ovarian cancer is 5.4-8.0 per 100,000 in India. Various versions of risk of malignancy index have been studied to show its validity in different settings. We have studied third version of risk of malignancy index in a resource poor setting in India.Methods: In this prospective observational study 74 perimenopausal and postmenopausal women with ovarian mass were recruited. Menopausal score (M), Ultrasonography score (U) and CA-125 are components of Risk of Malignancy Index 3. Patients underwent preoperative ultrasonography and CA-125 level was assessed. Scores of M 1-3, U 1-3 and absolute value of CA-125 was multiplied. This product was value of Risk of Malignancy Index 3. If it is less than 250 it suggests absence of malignancy and more than 250 strongly suggests malignancy. Results were confirmed by histopathology.Results: Fifty six percent women were cancer positive. Ovarian malignancy was more common in postmenopausal age group. Ultrasonography and CA-125 had high sensitivity of 90% but poor specificity. Risk of malignancy index 3 had a sensitivity, specificity, positive predictive value and negative predictive value of 90%, 91%, 78% and 96% respectively at a cut off value of 250.Conclusions: Risk of malignancy index was concluded to be a multimodal approach with better diagnostic scoring index in preoperative stage in women of ovarian masses. It is simple and easily applicable clinical tool in resource poor setting

Solution of the distributional equation and Green’s functions for scattering problems

AbstractA general method is described to obtain Green’s functions involved in nuclear scattering theory problems. By imposing specified boundary conditions on the general solution to the distribution equation, one can readily obtain the Green’s function for the radial Schrödinger equation

Pharmacokinetic profile of phytoconstituent(s) isolated from medicinal plants—A comprehensive review

AbstractHerbal medicine, the backbone of traditional medicine, has played an important role in human health and welfare for a long period. Traditional therapeutic approaches of regional significance are found in Africa, South and Central America, China, India, Tibet, Indonesia, and the Pacific Islands. The considerable scientific significance and commercial potential of traditional medicines have resulted in increased international attention and global market demands for herbal medicines, especially Chinese herbal medicines. Herbal medicines currently are the primary form of health care for the poor in the developing countries, and also are widely used as a supplement or substitute for conventional drugs in developed countries. These traditional medicines have a pivotal role in the treatment of various ailments and more than 50% of drugs used in Western pharmacopoeia are isolated from herbs or derived from modifications of chemicals found in plants. Herbal medicines usually contain a complex mixture of various bioactive molecules, which make its standardization complicated, and there is little information about all compounds responsible for pharmacological activity. Several research papers have been published that claim pharmacological activity of herbal medicines but few are discussing the role of the exact phytoconstituent. Understanding the pharmacokinetic profile of such phytoconstituents is essential. Although there are research papers that deal with pharmacokinetic properties of phytoconstituents, there are a number of phytoconstituents yet to be explored for their kinetic properties. This article reviews the pharmacokinetic profile of 50 different therapeutically effective traditional medicinal plants from the year 2003 onward