Construction News – heavy construction news

Combining neutron and X-ray imaging gives clues to how ancient weapons were manufactured

Each atomic layer thin, tear-resistant, and stable. Graphene is seen as the material of the future. It is ideal for e.g. producing ultra-light electronics or highly stable mechanical components. But the wafer-thin carbon layers are difficult to produce. At the Technical University of Munich (TUM), Jürgen Kraus has manufactured self-supporting graphene membranes, and at the same time systematically investigated and optimized the growth of the graphene crystals.

Graphene breaks all records. It is the thinnest and most stable material in the world, ultralight, tear-proof, electrically conductive, and highly resilient. Since it was discovered in 2004, the two-dimensional structures composed of carbon atoms have fueled the imagination and inventive spirit. Science fiction authors consider the material suitable for building cables to drive space elevators. Material researchers are experimenting with graphene displays, transistors, and electrodes, which purport to make the electronics of the future lighter, more stable, and longer-lived. In the scientific community, films of highly pure graphene are highly coveted, as they allow gases and liquids to be packaged in an ultra-dense manner.

“Currently, however, the basic requirements are still lacking. There are various manufacturing processes which are suitable for the mass production of graphene. However, this material is not free of defects. Graphene of the highest crystalline quality cannot be reproducibly manufactured in this manner,” explains Sebastian Günther, Professor for Physical Chemistry at the TUM. His team has now succeeded in analyzing, monitoring, and optimizing the growth of graphene crystals through chemical vapor deposition (CVD for short). The findings were recently published in the Annalen der Physik (Annals of Physics).

Theory and caveats in practice

Theoretically, it is very easy to produce graphene: All that is needed are a heated glass vessel, a reactor, in which carbon-containing gas such as methane is fed into, as well as copper as a catalyst. At temperatures of around 1,000 degrees Celsius, the methane decomposes on the copper surface to produce hydrogen and carbon. While the hydrogen subsequently leaves the copper surface, the carbon atoms collect on the surface of the copper film used during this chemical precipitation from the gaseous state — a process called chemical vapor deposition. Here, the atoms cross-link and form graphene “flakes,” spot-like two-dimensional structures with the typical honeycombed structure. What remains is the hydrogen, which can be extracted via suction.

However, in practice, the devil is in the details. “The biggest problem is that the two-dimensional crystal structure is often not entirely homogeneous, because growth begins simultaneously at multiple locations,” explains Jürgen Kraus, who carried out the experiments. “At first glance, it appears that a continuous graphene film is appearing on the copper, but the hexagonal honeycombs are not all oriented in the same manner, and the structure is weakened at locations where they meet.”

Such defects can be avoided by ensuring that the surface of the copper is as free of crystallization nuclei as possible.

With his experiments, the chemist was able to demonstrate that contaminants could best be removed with the help of oxygen gas — i.e. through oxidation. However, in order to avoid undesirable side effects, care must be taken to ensure that the copper catalyst is only exposed to the minimum possible amounts of oxygen.

Crucial for success: Gas concentration and temperature

In the second part of his experiments, Kraus analyzed how various partial pressures and temperatures affect the formation of graphene during chemical vapor deposition. If the gas composition used contains too much hydrogen, no graphene grows at all; if it has too little hydrogen, the layers become too thick. It is only when all parameters are selected such that growth occurs “close enough” to the thermal equilibrium that highly pure graphene without defects is formed in a crystal lattice.

Quality check in Italy

In order to verify the quality of the flakes, the Munich-based researchers took a trip to Italy with their samples. At the Research Centre Elettra Sincrotrone Trieste, which is equipped with a ring-shaped particle accelerator, they were able to chemically and structurally characterize the graphene layers with a special microscope, which had a high resolution thanks to the high-energy synchrotron radiation.

“The results of the feasibility study were highly encouraging,” reports Günther. “The images have shown that reproducible results can be obtained by selecting the parameters during chemical vapor deposition”

The TUM researchers’ best record for quality so far: Graphene flakes measuring one square millimeter containing ten billion precisely aligned carbon atoms. “The advantage over other studies is not so much the ‘record size’ achieved, but lies in the fact that the flakes are formed with a predictable growth rate if the right CVD parameters are chosen, thereby allowing closed, highly crystalline graphene layers with a thickness of just one atom to be manufactured within just a few hours,” summarizes Günther.

Mini films for new applications

Graphene opens up a wide range of new applications, above all in basic research: For one, the ultra-thin graphene films can e.g. be removed from the copper substrate and used as covering films. Such films are suitable for trapping liquids in a container. Because the films are transparent to slow electrons, the samples can be studied via electron spectroscopy and microscopy, even though these techniques are typically used in ultra-high vacuums or high vacuums.

With the help of the films, the researchers also intend to investigate living cells, liquid-covered electrodes and catalysts under high pressure via photoelectron spectroscopy in the future. In this process, photons, which are able to penetrate the film, transfer their energy to the electrons in the sample, such that they are released and pass through the film to the outside. Their energy levels can then be used to derive conclusions regarding the chemical composition of the sample.

Jürgen Kraus was awarded the Evonik Research Prize for his work.


Source link

#ConstructionNews – #Construction #News & #videos
#Godbless

Rejoice always, pray continually, give thanks in all circumstances; for this is God’s will for you in Christ Jesus.

Republished by Blog Post Promoter

Heavy Construction photos – Wuding Road / Changde Road – #heavy #construction #photos

Wuding Road / Changde Road

800 x 1200

Posted by Lowcola on 2013-06-08 11:21:55

Tagged: , shanghai , construction , destruction , demolition

Heavy Construction photos – Wuding Road / Changde Road – #heavy #construction #photos #pics and #images for you.

Therefore keep watch, because you do not know on what day your Lord will come.

Republished by Blog Post Promoter

Heavy Construction News – #Construction #news today

(Reuters) – Sears Holdings Corp’s shares soared 20 percent after the struggling retailer said it would sell its Kenmore home appliances on Amazon.com and integrate the brand’s smart gadgets with the online giant’s Alexa digital assistant.

The deal will expand the distribution reach of Kenmore products, potentially giving a fillip to the company’s sales, which have been falling for years amid intensifying competition from Wal-Mart Stores Inc and Amazon.

Syncing “smart” Kenmore appliances, such as connected room air conditioners, with Alexa, will allow users to control the gadgets with voice commands.

Sears joins an increasing number of retailers and manufacturers, including Whirlpool Corp, Ford Motor Co and Starbucks, which are integrating their products with Alexa as they look to garner sales through the popular digital assistant.

Alexa controls Amazon Echo, a speaker which lets the user call a cab, order pizza or shop on Amazon among other things.

Investors cheered Sears’ deal – the stock was set for its best day in about four months.

Store-based retailers are increasingly looking to sell more online as they struggle with falling store traffic and growing competition from Amazon.

Footwear maker Nike Inc also said last month it would start selling a limited product assortment directly on Amazon, rather than through third-party and unlicensed dealers.

Reporting by Sruthi Ramakrishnan in Bengaluru; Editing by Saumyadeb Chakrabarty


Source link

#Heavy #Construction #News – #Construction #news today

I cried out to him with my mouth; his praise was on my tongue.

Republished by Blog Post Promoter

Heavy Construction photos – Construction Site 025 – #heavy #construction #photos

Construction Site 025

Posted by Orange County Transportation Authority on 2011-07-21 20:47:00

Tagged: , Construction Site

Heavy Construction photos – Construction Site 025 – #heavy #construction #photos #pics and #images for you.

If you declare with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved.

Republished by Blog Post Promoter

Heavy Construction photos – Heavy equipment 5 – #heavy #construction #photos

Heavy equipment 5

Posted by kyprianoukck on 2010-12-16 00:59:22

Tagged: , Construction , eqpt

Heavy Construction photos – Heavy equipment 5 – #heavy #construction #photos #pics and #images for you.

For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.

Republished by Blog Post Promoter

Heavy Construction photos – Northfield Aldi construction – #heavy #construction #photos

Northfield Aldi construction

Northfield Aldi construction 10-5-09

Posted by The Development of Birmingham on 2009-05-11 02:24:51

Tagged: , northfield , birminghamuk , construction , aldi

Heavy Construction photos – Northfield Aldi construction – #heavy #construction #photos #pics and #images for you.

Good and upright is the Lord; therefore he instructs sinners in his ways. He guides the humble in what is right and teaches them his way.

Republished by Blog Post Promoter

India – Our Customers’ Voice: Patel Infra Pvt Ltd – #CASE #Construction #Equipment #Videos

India - Our Customers' Voice: Patel Infra Pvt Ltd


Patel Infrastructure Pvt. Ltd. established in year 1972, is one of the leading and emerging Infrastructure Company in India. The company is involved in the business framework of construction of roads and highways, bridges, irrigation and mining projects, construction of commercial buildings, and other ancillary services like toll collection, operation and maintenance of highways. Their CASE fleet comprises of 6 motor graders which are being used for construction of national highway road project in Northern part of India.

source
#CASE #Construction #Equipment #Videos

Heavy Construction Videos – Rohit sharma visit in John deere company – #Construction #Videos #HeavyConstruction


source
Heavy Construction Videos – #Construction #Videos #HeavyConstruction
#Godbless

I give them eternal life, and they shall never perish; no one will snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Father’s hand. I and the Father are one.

Republished by Blog Post Promoter

Heavy Construction photos – Coastal road expansion – #heavy #construction #photos

Coastal road expansion

Posted by wapogwapo on 2013-06-21 13:32:56

Tagged: , iloilo road , road construction , iloilo

Heavy Construction photos – Coastal road expansion – #heavy #construction #photos #pics and #images for you.

Each of us should please our neighbors for their good, to build them up.

Republished by Blog Post Promoter

JIVA: Sita’s Story- Sharing #JohnDeere #Videos and #information



JIVA is the Joint Initiative for Village Advancement, a multi-year program created by the John Deere Foundation and PYXERA Global dedicated to improving the lives of those in three adjacent villages in rural India—Morra, Madara, and Sakrawas. JIVA traces its roots to a volunteer project led by John Deere CEO Sam Allen in 2011, when a team of the company’s employees worked for a week side-by-side with Sita and other farmers to learn firsthand the challenges they face. This is Sita’s story.

source
Sharing #JohnDeere #Videos and #information

Cat® Machines Equip Dilip Buildcon for Success – Sharing #caterpillar #Videos and #products

Cat® Machines Equip Dilip Buildcon for Success


What does it take to become one of the most successful and largest infrastructure construction companies in India? It takes corporate vision and dedication. It takes exemplary, well trained, employees. It takes safe, reliable and productive earth moving equipment that comes with 100% system support. The kind of equipment and support that only comes from Caterpillar. Learn More: http://bit.ly/1Eu4k02

source
Sharing #caterpillar #Videos and #products

D5292_CM-230

D5292_CM-230

Posted by MoDOT Photos on 2010-11-10 20:01:50

Tagged: , construction , obliques , stimulus

Heavy Construction photos – D5292_CM-230 – #heavy #construction #photos #pics and #images for you.

He has shown you, O mortal, what is good. And what does the Lord require of you? To act justly and to love mercy and to walk humbly with your God.

Republished by Blog Post Promoter

Brickmania US Navy Seabee tractors (2)

Brickmania US Navy Seabee tractors (2)

Heavy Tractor (with steel Track Links) and Light Tractor.

For a forthcoming review on The Brothers Brick.

Posted by Dunechaser on 2014-02-11 15:41:45

Tagged: , LEGO , military , US , Navy , Seabee , construction , tractor , engineering , World War II , World War 2 , WW2 , BrickArms

Heavy Construction photos – Brickmania US Navy Seabee tractors (2) – #heavy #construction #photos #pics and #images for you.

All this also comes from the Lord Almighty, whose plan is wonderful, whose wisdom is magnificent.

Republished by Blog Post Promoter

Weather Gone Viral: Bridge Collapse – #Weatherchannel #news and #videos



Heavy monsoon rain and flooding caused this river to swell and bridge to collapse. Don’t miss a new episode of Weather Gone Viral Sunday at 9:00pET, only on The Weather Channel!

source
#weatherchannel #weathernetwork news & videos – Weather Gone Viral: Bridge Collapse – #weather #news #videos