This fruit reeks, but it may one day power your phone
Ever smell a durian fruit? Don't. Think of it as nature's stinky battery.
- New research finds that jackfruit and durian, often called the world's smelliest fruit, make outstanding supercapacitors.
- Supercapacitors are useful because they can be used as infinitely rechargeable batteries.
- The study, published in the Journal of Energy Storage, also demonstrates the development of carbon aerogels for the bodies of the fruit batteries.
It's said to be delicious, but you probably haven't encountered any durian fruit-scented candles. That's because it smells, as the late gourmand Anthony Bourdain put it, "indescribable, something you will either love or despise…Your breath will smell as if you'd been French-kissing your dead grandmother."
Eye-watering odor aside, Vincent G. Gomes of the University of Sydney and his colleagues have discovered that durian fruit has an amazing and potentially useful property: It's a natural supercapacitor. In a paper published in the Journal of Energy Storage, Gomes explains that supercapacitors are "promising for energy storage due to their superior cycling stability and excellent charge–discharge ability." Unfortunately, they also often suffer from low capacitance and stability. Stinky durian fruit and its cousin, jackfruit, don't have those issues.
We need a better battery
Image source: PandaMath/Shutterstock
Researchers have been trying to move away from existing lithium-ion batteries that contain chemicals whose interactions produce electricity. When those chemicals are depleted, what's left is a little bundle of toxic waste.
A capacitor, on the other hand, stores energy by building up a static electricity charge on the surfaces of two metal plates. (You might think of how static electricity builds up on your hair when you rub a balloon against your head, for a sense of how this works.) However, capacitors can't hold a lot of energy, nor can they hold it for long. Still, they are infinitely rechargeable, unlike lithium-ion solutions.
Supercapacitors begin to address some of these problems. They typically contain metal plates which have more surface-area and are coated with a second layer of activated charcoal or a similar material. This makes them better at soaking up and holding a charge. Still, supercapacitors are expensive to produce and have their own stability issues.
So now imagine one made of durian fruit or jackfruit. Gomes' paper describes the potential:
"The structural precision of natural biomass with their hierarchical pores, developed over millions of years of biological evolution, affords an outstanding resource as a template for the synthesis of carbon-based materials. Their integrated properties of high surface area, in-plane conductivity and interfacial active sites can facilitate electrochemical reactions, ionic diffusion and high charge carrier density."
Jacking into durian fruit
The bodies of the fruit batteries are made of aerogels: durian carbon aerogel (DCA) and jackfruit carbon aerogel (JCA). The process of deriving them seems complicated, but hey, science is hard.
First, the researchers scrubbed small bio samples from the spongy core of each fruit. Next, the samples were rinsed with ionized water several times to clean them. Placed in autoclaves, they were steamed hydrothermally for 10 hours at 180° C. After cooling off, they were rinsed again and then freeze-dried in a -80° C vacuum over the course of 24 hours. Following that, they were heated to 800° C and held at that temperature for an hour. Overnight ambient cooling yielding black, highly porous, ultralight aerogels. Easy-peasy.
For electrodes, each DCA and JCA battery was fitted with two electrodes, and two different electrode arrays were tested.
The first array, designed to allow an electrochemical measurement of the batteries' performance, incorporated a pair of glass substrates, each coated with an ink comprised of either DCA or JCA powder, respectively, and mixed with carbon black, polyvinylidene fluoride, or a PVDF binder.
The second electrode array used a pair of glass substrates coated with indium tin oxide, with a prepared PP (Celgard) separator between them. This architecture allowed appraisal of the battery's gravimetric capacitance.
The authors' conclusions
The paper concludes that "both electrodes are attractive candidates for the next generation, high performance, yet low-cost supercapacitors for energy storage devices derived from biowastes." In both the DCA and JCA variants, "the electrodes…displayed long-term cycling stability, and rapid charge–discharge processes. " It turns out that the durian fruit battery has a bit more power-storage capacity than its jackfruit cousin. The paper makes no mention of the final olfactory personality of the batteries.
In addition to offering proof of the potential for using durian fruit and jackfruit for energy storage, the authors point out that for the first time, they've demonstrated the development of carbon aerogels "via a facile, chemical-free, green synthesis procedure."
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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