Rafael Martins

srtalumpy: El será tu mejor amigo…pero tu no sé, eh?

ULN2003 – practical example of «reading» microchip schematic via Evil Mad Scientist

We often receive comments that while out microchip photos are beautiful and interesting, it is completely unclear how integrated circuit implements basic elements and form larger circuit. Of course it is impossible to do a detailed review of an 1’000’000 transistor chip, so we’ve found simpler example: ULN2003 – array ofDarlington transistors.

Despite it’s simplicity this microchip is still widely used and mass manufactured. ULN2003 contains 21 resistors, 14 BJT transistors and 7 diodes. It is used to control relatively high load (up to 50V/0.5A) from microcontroller pin. Canonical use case – to control segments of large 7-segment LED displays.

What’s inside the ULN2003 Darlington driver chip - [Link]

Está um pouco fora de hora, mas nunca é tarde pra ver o Papa comendo meleca.

When Democratic Rep. Mark Takano got his hands on a draft letter to Speaker John Boehner from conservatives on immigration, he did what any pro-reform member of Congress who was a high school literature teacher for two decades would: took out his red pen and marked up the draft.

Nerval's Lobster writes "For the second time in a month, Hewlett-Packard has been forced to admit it built secret backdoors into its enterprise storage products. The admission, in a security bulletin posted July 9, confirms reports from the blogger Technion, who flagged the security issue in HP's StoreOnce systems in June, before finding more backdoors in other HP storage and SAN products. The most recent statement from HP, following another warning from Technion, admitted that 'all HP StoreVirtual Storage systems are equipped with a mechanism that allows HP support to access the underlying operating system if permission and access is provided by the customer.' While HP describes the backdoors as being usable only with permission of the customer, that restriction is part of HP's own customer-service rules—not a limitation built in to limit use of backdoors. The entry points consist of a hidden administrator account with root access to StoreVirtual systems and software, and a separate copy of the LeftHand OS, the software that runs HP's StoreVirtual and HP P4000 products. Even with root access, the secret admin account does not give support techs or hackers access to data stored on the HP machines, according to the company. But it does provide enough access and control over the hardware in a storage cluster to reboot specific nodes, which would 'cripple the cluster,' according to information provided to The Register by an unnamed source. The account also provides access to a factory-reset control that would allow intruders to destroy much of the data and configurations of a network of HP storage products. And it's not hard to find: 'Open up your favourite SSH client, key in the IP of an HP D2D unit. Enter in yourself the username HPSupport, and the password which has a SHA1 of 78a7ecf065324604540ad3c41c3bb8fe1d084c50. Say hello to an administrative account you didn't know existed,' according to Technion, who claims to have attempted to notify HP for weeks with no result before deciding to go public."

Read more of this story at Slashdot.

Being an enlightened individual means understanding basic scientific information about how the world works. Sure, we have teachers and parents there to fill our brains with knowledge, but the sad truth is that there are certain facts that take on a life of their own as they pass from ear to ear, eventually etching themselves into our collective brain-mass in twisted forms that are, well, just plain wrong.

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Una buena forma de entender la investigación es realizando experimentos curiosos y asombrosos, que llamen nuestra atención y despierten nuestra curiosidad. Hoy os contamos algunos.

Normalmente en ALT1040 os contamos las últimas novedades sobre ciencia, tratando de enfocar los diferentes temas de medicina, astronomía o biología desde la perspectiva más amena posible.

Esto hace que muchas veces veamos a la investigación como algo soso o incluso aburrido. Pero no debemos ver a los científicos como personas encerradas en sus torres de marfil, sino más bien como curiosos acerca de lo que ocurre en el mundo.

Es interrogarse una y otra vez "¿por qué?" lo que da sentido a la investigación, y a veces, encontramos respuestas incluso en...algo como los GIFs de ciencia que explicamos hoy.

La reacción de la «espuma»

Una de las cosas más divertidas que se pueden hacer en un laboratorio de ciencias es experimentar diferentes tipos de reacciones químicas, siempre con la suficiente supervisión y seguridad, para ver qué ocurre. Y viendo cómo funcionan, es más sencillo que podamos entender algunas de las partes más complicadas de la química.

Por ejemplo, en el primer caso que vemos hoy dentro de los GIFs de ciencia, se trataba de mezclar peróxido de hidrógeno con yoduro potásico. ¿Qué hace que salga tanta espuma tras realizar la reacción? La explicación nos la comentan en detalle en esta revista, en la que nos explican que el peróxido de hidrógeno, más conocido como agua oxigenada, puede descomponerse en agua (H20) y oxígeno molecular (O2).

El yoduro potásico acelera la descomposición del agua oxigenada, de forma que ocurre una reacción exotérmica (es decir, que libera calor), por lo que parte del agua que se desprende se encuentra en forma de vapor.

Además, la coloración marrón que observamos se debe, como se explica en el artículo mencionado antes, a que "algunos aniones yoduro se oxidan a yodo molecular, que reacciona con aniones yoduro presentes para formar el anión triyoduro". Una buena forma de entender algunas reacciones químicas, sin duda, y que además nos sirve para comenzar esta recopilación de GIFs de ciencia.

La extraña polimerización

En el segundo ejemplo de nuestra recopilación de GIFs de ciencia, vemos la polimerización de la p-nitroanilina. Este compuesto, también conocido como 4-nitroanilina o incluso 1-amino-4-nitrobenceno, es un compuesto orgánico que responde a la fórmula de C6H6N2O2.

Comúnmente es utilizado como intermediario en la producción de colorantes, insecticidas o fármacos, tratándose de un polvo de color amarillo brillante, con cierto olor a amoníaco. Como nos recuerdan en este informe, es una sustancia química peligrosa, que se debe manipular con cuidado.

En la siguiente animación, lo que se observa es la polimerización de este compuesto químico, que se trata en cierta manera de una reacción química bastante explosiva. Ocurre debido a que añadimos a la taza de cerámica con p-nitroanilina ácido sulfúrico concentrado.

La cuchara que se derrite

Otro de los GIFs de ciencia más asombrosos es el siguiente, en el que vemos una cuchara metálica que, literalmente, se derrite en un vaso de agua. Increíble, ¿verdad? ¿Por qué ocurre?

Para entender el proceso, primero debemos analizar el material del que está hecho la cuchara: galio. Como nos cuentan en este blog, el galio es un elemento químico cuyo punto de fusión es de solo 28,56ºC. De este modo, aunque la cuchara en principio parece de acero, no lo es, y esta peculiaridad hace que se "derrita" en un vaso de agua templada.

Tiocianato de mercurio

La última animación increíble en esta lista de GIFs de ciencia que veremos hoy trata sobre la descomposición térmica del tiocianato de mercurio. Este compuesto químico se utiliza habitualmente en laboratorios de análisis o de química fina.

Y aunque podríamos pensar que se trata de un ser alienígena revolviéndose, lo cierto es que la respuesta a este extraño fenómeno se encuentra en que cuando arde crea unas "estructuras parecidas a una serpiente". La reacción química que se produce es alucinante, aunque hay que recordar la alta toxicidad que tiene este compuesto al manipularlo en cualquier laboratorio.

Como vemos, la ciencia no solo favorece nuestro día a día, con complejos experimentos y proyectos de investigación, muchas veces difíciles de comprender. También es una forma de entender y saber más acerca del mundo que nos rodea, con increíbles y asombrosos trucos, que muchas veces no acertamos a entender del todo.

I ordered and received my Bug-a-salt gun late last fall, pretty late in the fly season to really get to put it to serious use. Well, early spring in Western Washington and they are coming back. Over the years I became very proficient with rubber bands, hunting flies and yellow jackets – this takes it to a whole new level.

The Bug-a-salt doesn’t “cream” the flies, leaves them pretty well intact, but it is quite effective. Non-toxic, environmentally friendly, it is spring powered and doesn’t eat batteries. Just table salt.

The gun has sights, but due to the shot pattern and the height of the sights above the bore for me it is a “point and shoot” proposition. A sheet of aluminum foil taped to the wall works well to pattern the shot, like a patterning board for a shotgun. It lets you see the spread of the salt, and calculate your effective range. I am definitely getting better. It is possible to shoot flies out of the air. There is nothing else like it.

The invention and marketing of this product are a story unto itself. I ordered mine early, when they were setting up for manufacture and was able to follow the trials and tribulations of getting this to market. The exportation to some of the countries they had orders from were amazingly complicated.

This year I switched to Morton Kosher salt and find it works better on flies than the table salt. Last year’s tests on yellow jackets were exciting, but not effective. Maybe with the kosher salt…

-- Norm Bolser

[This is a Cool Tools Favorite from 2013]

Bug-a-Salt

Available from Amazon

In July 1968, ethologist John B. Calhoun built a “mouse utopia,” a metal enclosure 9 feet square with unlimited food, water, and nesting material. He introduced four pairs of mice, and within a year they had multiplied to 620. But after that the society began to fall apart — males became aggressive, females began neglecting their young, and the weaker mice were crowded to the center of the pen, where resources were scarce. After 600 days the females stopped reproducing and the males withdrew from them entirely, and by January 1973 the whole colony was dead. Even when the population had returned to its former levels, the mice’s behavior had remained permanently changed.

There were no predators in the mouse universe; the only adversity was confinement itself. Calhoun felt that his experiment held lessons as to the potential dangers of human overpopulation, and he urged his colleagues to study the effects of high population density on human behavior. “Our success in being human has so far derived from our honoring deviance more than tradition,” he said. “Now we must search diligently for those creative deviants from which, alone, will come the conceptualization of an evolutionary designing process. This can assure us an open-ended future toward whose realization we can participate.”

(Thanks, Pål.)

credit: Annie