Science in Brief

Security flaws in smart home products discovered
Smart home products such as lamps controlled via mobile devices are becoming ever more popular in private households. However, researchers at the IT Security Infrastructures group, Friedrich-Alexander University Erlangen-Nürnberg (FAU) in Germany have discovered security problems in smart lights from many of the major manufacturers on the market.

The team managed to make connected lighting systems from different manufacturers flash for several hours with a single radio command sent from a distance of more than 100 m away. Additionally, they were able to modify the bulbs using radio commands so that the user was unable to control them. It was even possible in certain situations to change the colour or brightness of the light.

The FAU researchers discovered the security weaknesses in ZigBee, an important wireless standard employed for the control of smart home products. More than 100 million products that use ZigBee technology are estimated to have been distributed around the world. The most recent version, ZigBee 3.0, was released in December 2016. Part of this specification includes the touchlink commissioning procedure for adding new devices to an existing smart home network or to set up a new network. The team was able to demonstrate that the security features of touchlink commissioning are inadequate and make it vulnerable to attack. It is probable that other applications based on ZigBee that are relevant to security, such as heating systems, door locks and alarm systems, will also be affected in the future.

The research team recommended disabling touchlink commissioning in all future ZigBee 3.0 products. The latest information is published on the following website: www1.informatik.uni-erlangen.de/content/zigbee-security-research.

Smartphone screen technology used to trick harmful bacteria
Conducting plastics found in smartphone screens can be used to trick the metabolism of pathogenic bacteria, report scientists at the Swedish Medical Nanoscience Centre at Karolinska Institute. By adding or removing electrons from the plastic surface, bacteria may be tricked into growing more or less.

When bacteria attach to a surface they grow quickly into a biofilm, which can be dangerous, especially in a hospital setting where they can cause life-threatening infections. Researchers are looking to address this problem by producing coatings for medical devices made from a cheap conducting plastic called PEDOT, which is what makes smartphone screens respond to touch. By applying a small voltage, the PEDOT surface was either flooded with electrons or left almost empty, which in turn affected the growth of salmonella bacteria.

"When the bacteria land on a surface full of electrons, they cannot replicate," explains principal investigator Prof Agneta Richter-Dahlfors, director of the Swedish Medical Nanoscience Centre. "They have nowhere to deposit their own electrons which they need to do in order to respire."

On the other hand, if the bacteria encountered an empty PEDOT surface, the opposite happened and they grew to a thick biofilm.

The research team therefore could either stop bacterial growth - by coating medical devices to make them more resistant to colonisation by bacteria for example - or let it continue. The latter would be useful for industries like wastewater management where beneficial biofilms are used to make clean water.

In the future the research team wants to integrate this technology with devices that could one day be implanted into patients to keep them safe when undergoing medical procedures or having devices implanted.

New way to make dissolving electronics
Researchers from the University of Houston in the US and China have reported a new type of electronic device that can be triggered to dissolve through exposure to water molecules in the atmosphere.

The work holds promise for eco-friendly disposable personal electronics and biomedical devices that dissolve within the body. There are also defence applications, including devices that can be programmed to dissolve in order to safeguard sensitive information.

The field, known as physically transient electronics, currently requires immersion in aqueous corrosive solutions or biofluids. The team's work, however, demonstrates a completely new working mechanism: the dissolution is triggered by ambient moisture. Functional electronic components are built via additive processes onto a film made of the polymer polyanhydride. The device remains stable until ambient moisture triggers a chemical breakdown that digests the inorganic electronic materials and components. The lifespan of the devices can be controlled by varying the humidity level or by changing the polymer composition.

The researchers tested a number of compounds, including aluminium, copper, nickel indium-gallium, zinc oxide and magnesium oxide, and developed various electronic devices, including resistors, capacitors, antennas, transistors, diodes, photo sensors and more, to demonstrate the model's versatility.

Embracing 'DfMA' in the run-up to Hong Kong 2030+

Design for manufacture and assembly (DfMA) is a term increasingly heard in the construction industry. It involves prefabricating modular units off site in factory conditions, then assembling them together on site.

It is a technique that avoids many of the piecemeal tasks involved in traditional construction - and is a very welcome development for a number of reasons. Much of the DfMA process is carried out in a controlled environment, so quality improves, with less material waste. The production line efficiencies of factory production cuts the time it takes to produce individual units, speeding up overall construction programmes. And reduced work on site means less need for workers to contend with bad weather and the hazards and distractions of the construction site, increasing safety.

DfMA is already in use in Hong Kong's construction industry, with prefabricated service risers, plant rooms and bathroom units being used in several public housing projects. And the potential for DfMA to bring cost, time and safety benefits to other parts of the construction industry is nearly limitless. But despite the urgent need and the obvious benefits, there are three key barriers to embedding DfMA in Hong Kong:

1. Prefabrication requires designers and contractors to collaborate closely to fix and detail the design, ready for manufacture off-site. This works for 'design and build' projects as the designer and contractor are in the same team, but this is not a very common model in Hong Kong.
2. The fast-paced bidding process allows too little time for the development of innovations that can add significant value through design, manufacture and assembly. Raising awareness of the benefits of DfMA will encourage clients to favour these projects.
3. Building regulations are well adapted to traditional construction solutions, but pose challenges to DfMA projects. Adapting the approvals process to this new technology will encourage more take-up of prefabrication.

All of these challenges can be overcome if the government and developers work closely with designers, engineers and contractors to support stronger take-up of DfMA. Some organisations, such as the Construction Industry Council and University of Hong Kong, are showing real leadership in this field, and it is time for others to follow their lead.

"And there could be no better time to promote the benefits of DfMA in the industry. There is already a surge of new projects in anticipation of Hong Kong 2030+, the government's infrastructure development strategy that will shape the built environment of the territory for decades to come, with many more projects in the pipeline," said Paul Lengthorn, business development director of Mott MacDonald.

Embracing DfMA will make this unprecedented construction boom as safe, cost-effective and innovative as possible.

This article is contributed by Mott MacDonald.


Prefabrication requires designers and contractors to collaborate closely to fix and detail the design

Book Review
By Ir Dr F C CHAN

Contract essentials for construction professionals

The book, Construction Contract Essentials in Hong Kong (edited by Gary Soo and published by HKU Press), gives readers the essentials of contract law and is particularly useful for engineers in the construction industry. It is also a good and handy reference for legal professionals handling construction contracts. It is concise yet quite comprehensive. In some 160 pages divided into eight chapters, the book covers virtually all key areas of concern for those handling building and construction contracts.

The book is logically sequenced to first give an overall view of the trend in construction contract procurement using the new form of contract; that is, NEC3, as an illustration. This chapter could be read in conjunction with Chapter 3, which covers the latest contract form used by the Government for civil contracts, which is the very type of contract attracting frequent contractual claims and arguments.

Chapter 2 gives a very comprehensive coverage on the interpretation of construction contracts, elaborating in an understandable manner the otherwise rather complex legal concepts that are of value to building engineering professionals, not only enabling them to be better 'users' of a contract drafted by others, but also enabling them to be better contract drafters.

Following from Chapter 2, Chapter 3 highlights some important contractual provisions in common use in Hong Kong, notably the Government General Conditions of Contract for Civil Engineering Works. The foci are on work commencement, liquidated damages, variation and delay recovery. This chapter gives a comprehensive update on the provisions for these subjects and the latest on these areas. Cases and judgements are cited as illustrations to help readers gain a concrete understanding of the contract laws 'in action'.

Chapter 4 and 5 address breach of contract, measurement of damages and assessment on claims in money terms and in time. These are issues on the daily agenda of all construction professionals. The exploration is contextualised around a couple of key cases, such as Robinson v Harman, Hadley v Baxendale, the Victoria Laundry, Heron II, and the Achilleas, to bring out and elaborate the legal principles established over the years through these key cases.

Chapter 5 is a compendium of legal principles on assessing claims and quantifying time. It is a handy and concise reference on this subject for not just construction professionals, but legal practitioners as well. It is also useful for finding the applicable legal authorities and principles relevant to their work.

Chapter 6 covers non-payment which could lead to or taken by the innocent party as repudiation or termination of a contract before all contracting parties have discharged their respective obligations as stipulated in the contract. This chapter is structured under headings of rights and obligations of parties, with the legal concept illustrated by a wealth of authorities.

Chapter 7 concludes the main body of the book as far as contract law is concerned. It addresses mistakes and misrepresentation which are not uncommon as 'eye-sores' in building contracts. Given the great volume of documents included in contracts, or being referred to by the contracts, as well as the information and material generated during the pre-contractual stages, these are understandably areas of frequent disputes. Again the book drives home all the relevant legal principles by reference to key authorities.

Unlike other legal texts, this book concludes with a chapter which touches on alternative dispute resolution, which are gaining increasing popularity as a more efficient and 'friendly' means of settling contractual disputes without going through the usually more lengthy and costly legal proceedings. This knowledge is one of the contract 'essentials' that all construction professionals should be equipped with to make them more effective in contract administration.

As a whole, this book is an informative and well-written compendium of contract essentials with rich sources of key authorities that are of great value to construction professionals with no prior legal training. It can also serve as a quick and handy reference for legal professionals who can use it as a quick refresher, or a starter for their more vigorous legal research.

Biomedical Note

Ir Prof Yongping Zheng appointed to Henry G Leong Endowed Professorship

The Hong Kong Polytechnic University (PolyU) has appointed Ir Prof Yongping Zheng to the Henry G Leong Endowed Professorship in Biomedical Engineering.

Ir Prof Zheng has served as the founding head of the Interdisciplinary Division of Biomedical Engineering since 2012. Ir Prof Zheng has an interdisciplinary background: he holds a bachelor's degree in electronics, a master's degree in acoustics and a PhD in biomedical engineering. After a postdoctoral fellowship in the Department of Physics, University of Windsor, Canada, he joined PolyU as an assistant professor in biomedical engineering in 2010, then associate professor and professor in 2005 and 2008, respectively. He served as the associate director of PolyU's Research Institute of Innovative Products from 2008 to 2010.

Ir Prof Zheng's research interests include biomedical ultrasound instrumentation and smart ageing technologies. He is a senior member of the Institute of Electrical & Electronic Engineers (IEEE), a Fellow of the Hong Kong Institution of Engineers (HKIE), past Chair of the Biomedical Engineering Division of HKIE, and honorary advisor of Hong Kong Medical & Healthcare Device Industry Association (HMHDIA). He serves as associate editor and editorial board members for some leading journals in the field. Ir Prof Zheng owns 35 patents, has published 220 journal papers, and wrote a book entitled "Measurement of Soft Tissue Elasticity In Vivo: Techniques and Applications". Some inventions of his team have successfully become products, including Scolioscan: a radiation-free assessment of scoliosis using 3D ultrasound.

The Endowed Professorship will enable Ir Prof Zheng to develop more innovative biomedical devices to benefit people with different diseases, particularly for screening and earlier diagnosis. Ir Prof Zheng has been inspired to contribute to the innovation and technology-based re-industrialisation of Hong Kong.

This article is contributed by the Biomedical Division.

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