Tag Archives: bottle

Can we empty bottles faster? Yes, and here’s how

At some point, all of us have watched a bottle get empty while pouring a drink. It’s just something normal that we do without overthinking it much, hoping to enjoy the beverage as soon as possible – especially on a hot summer day.

Credit Flickr

A group of researchers from the Indian Institute of Technology Roorkee has just discovered how to make bottles empty faster, which may seem trivial but actually has wide-ranging implications for many areas beyond the beverage industry.

For decades, studies have looked at the use of bubbles. Even Leonardo da Vinci observed the rise of bubbles in a pool. The growth dynamics of bubbles at the mouth of a bottle depends on the thermophysical properties of the fluid, the bottle geometry, and its angle of inclination. Taking advantage of the previous investigations, the researchers Lokesh Rohilla and Arup Kumar Das decided to explore further the bottle-emptying phenomenon, now from the perspective of bubble dynamics on a commercial bottle, by using high-speed photography.

They used image analysis to conceptualize various parameters, such as liquid film thickness, bubble aspect ratio, rise velocity, and bottle emptying modes. “Bubble dynamics inside the bottle are too complex to study, so we divided the bubble interfacial growth into different stages to comprehend them,” said Rohilla in a statement.

If you ever poured a drink, you are likely aware that the bottle empties faster if you angle it more. Doing so increases what’s known as bubble pinch-off frequency, and the relative increment depends upon the thermophysical properties of the fluid, the researchers said.

The temporal evolution of the bubble within different fluids. Credit: Lokesh Rohilla

The experiments done by Rohilla and Kumar suggested there’s a critical angle of inclination of bottles, after which a further increase in the inclination won’t lead to the bottle getting empty faster. “This occurs due to the saturation of the voidage, space occupied by air within the surrounding liquid, at the bottle’s mouth with the angle of inclination,” Rohilla explained.

Rohilla and Kumar identified two distinct bottle-emptying modes. In one, the discharge rate is increased due to a high-frequency pinch-off of air bubbles inside the bottle. In the other one, it is caused by an increase in the volume of the pinched-off bubble at a comparatively lower frequency.

“We’ve also observed an encapsulated bubble while discharging fluid in a vertically upended bottle,” Rohilla said. “Encapsulated bubbles have pinched off-sites outside the bottle mouth, contrary to intuition. The presence of a violent ejector jet within inviscid fluids, in which liquid becomes thin due to almost no internal friction, and its complete absence within viscous fluids control the periodicity of the bubbles.”

This work proves that bottle geometry and thermophysical properties play a role in reducing the time it takes for a bottle empty. “We can manipulate the bottle discharge pattern by manipulating bottle geometry,” said Das. “An intuitive product-specific bottle design will enable better control of its discharge rate.”

The beverage industry and chemical plants are among the applications that could benefit from this better understanding of bottle geometry, according to the researchers. The findings could even lead to new designs of bottles that allow pouring a drink much faster and efficiently.

The study was published in the journal Physics of Fluids.

Ancient baby feeder.

Tiny, ancient, animal-shaped pots were likely the first baby bottles

A team led by researchers from the University of Bristol reports on the earliest evidence of babies being fed animal milk — and of the ancient equivalent of modern-day baby bottles.

Late Bronze Age feeding vessels from Vösendorf, Austria.
Image credits Enver-Hirsch / Wien Museum.

Chemical analyses, as well as the context these vessels were discovered in, strongly suggest that they were used as baby feeders. The vessels were made from clay and first appeared in Europe around the Neolithic (late stone age, around 5,000 BC). Throughout the Bronze and Iron Ages, these vessels become increasingly more commonplace, the team explains.

Baby munchies

“These very small, evocative, vessels give us valuable information on how and what babies were fed thousands of years ago, providing a real connection to mothers and infants in the past,” says lead author Dr. Julie Dunne from the University of Bristol’s School of Chemistry.

The vessels are quite small — usually small enough that a baby could comfortably grip and hold them. They also have a spout through which liquid can be suckled and, in some of the more eye-catching variants, are shaped like animals or resembling animals. Although this does suggest that they were used as an equivalent of today’s baby bottles, we don’t have any direct evidence of their function. For example, they could very well have been made for the sick or infirm to use.

In order to find out what kind of foods these vessels were used to serve, the team analyzed three examples found in child graves in Bavaria. These vessels were small (about 5-10 cm across) with an extremely narrow spout. Food residues within the vessels showed that they contained ruminant milk (from domesticated cattle, sheep, or goats).

Ancient baby feeder.
Selection of Late Bronze Age feeding vessels from Vienna, Oberleis, Vösendorf, and Franzhausen-Kokoron (from left to right), dated to around 1200– 800 BC.
Image credits Katharina Rebay-Salisbury.

The presence of these specialized vessels in child graves, along with the presence of milk residue inside them, strongly suggests that these were used to feed animal milk to babies — in the place of human milk and/or during weaning onto supplementary foods.

The study represents our closest proven link between these vessels and child feeding. They’re also the most direct evidence of weaning practices we have to date — previously, these were inferred from isotopic analysis of infant skeletons, but that only gave us some bits of the puzzle. As such, the study fleshes out our understanding of breastfeeding and weaning practices, as well as infant and maternal health practices in prehistory.

She continued: “Similar vessels, although rare, do appear in other prehistoric cultures (such as Rome and ancient Greece) across the world,” Dunne explains. “Ideally, we’d like to carry out a larger geographic study and investigate whether they served the same purpose.”

The paper “Milk of ruminants in ceramic baby bottles from prehistoric child graves” has been published in the journal Nature.

water bottle

Renewable plastic made from CO2 and waste agriculture

Making bottles to meet America’s demand for bottled water uses more than 17 million barrels of oil annually, enough to fuel 1.3 million cars for a year. Instead of petroleum, Stanford researchers have found a creative way to make plastic for bottles sourced from CO2 and inedible plants like waste agriculture or grasses.

water bottle

Image: Pixabay


Most plastics today are made from  polyethylene terephthalate (PET), or polyester more commonly known. Each year about 50 million tons of PET are made to meet growing demand for electronics, food and beverage containers, personal-care products or fabrics.

To make PET, the industry uses , terephthalic acid and ethylene glycol, which are both derived from fossil fuels like petroleum and natural gas. For every ton of PET, four tons of CO2 are released according to Matthew Kanan, an assistant professor of chemistry at Stanford.

Kanan and colleagues investigated an alternative to PET called polyethylene furandicarboxylate (PEF) which can be sourced from biomass instead of petroleum. Moreover, PEF can seal oxygen better which makes it a more attractive material for bottling.

PEF is made from ethylene glycol and a compound called 2-5-Furandicarboxylic acid (FDCA). However, there are two challenges the industry faces with FDCA. For one, scaling the manufacturing process so it makes economic sense has been in vain. Secondly, though sourced from biomass, FDCA might actually be more harmful to the environment depending on where it’s made.

Traditionally, FDCA is made out of fructose sourced from corn syrup. This, however, displaces potentially usable farm land for edible agriculture. It also involves a lot of fertilizer, water and energy to grow. The Stanford researchers have orientated themselves to another feedstock: furfural, a compound made from agricultural waste. Some 400,000 tons are produced every year for use as solvents, resins and other products.

They used a benign and inexpensive compound called carbonate — one of the most widely distributed mineral around the planet and the stuff animals’ shells are made of. Mixing and heating carbonate, CO2 and furoic acid derived from furfural, the Stanford researchers formed a molten salt. Five hours later, 89 percent of the mixture converted to FDCA. Making PEF from FDCA is a straightforward process.

The researchers claim that using plastics made with this process will dramatically lower the carbon footprint of bottled beverages. The CO2 can be sourced from nearby power plants. Emissions are plentiful, as we all know. Products made of PEF can also be recycled or converted back to atmospheric CO2 by incineration. Eventually, that CO2 will be taken up by grass, weeds and other renewable plants, which can then be used to make more PEF.

“We believe that our chemistry can unlock the promise of PEF that has yet to be realized,” Kanan said. “This is just the first step. We need to do a lot of work to see if it’s viable at scale and to quantify the carbon footprint.”

Reference: Carbon dioxide utilization via carbonate-promoted C–H carboxylation, nature.com/articles/doi:10.1038/nature17185