Stephan Bullard

The use of aeration as a simple and environmentally sound means to prevent biofouling

Biofouling is a major problem faced by marine industries. Physical and chemical treatments are available to control fouling, but most are costly, time consuming or negatively affect the environment. The use of aeration (ie continuous streams of air bubbles) to prevent fouling was examined. Experiments were conducted at three sites with different benthic communities. Experimental panels (10 cm × 10 cm; PVC and concrete) were deployed with or without aeration. Aeration flowed continuously from spigots 0.5 m below the panels at a rate of ∼3.3 to 5.0 l min−1. After 1 and 4 weeks, aerated PVC panels from all sites had significantly less fouling than non-aerated controls. Aeration reduced fouling on both the PVC and concrete surfaces. Fouling was reduced on panels directly in bubble streams while panels 30 cm and 5 m away had significantly more fouling. Thus, under the conditions used in this study, aeration appears to be an effective and simple way to prevent fouling.

Seasonal Patterns of Ascidian Settlement at an Aquaculture Facility in the Damariscotta River, Maine

ABSTRACT Biofouling ascidians represent a serious and costly problem for aquaculture. Although the subject of intensive study for the past decade, little is still known about the timing, intensity, and duration of ascidian settlement, especially in coastal Maine. To assess ascidian settlement, PVC panels were deployed in the Damariscotta River, Maine, on a weekly basis during the summers of 2007 and 2008. Long-term fouling panels were deployed from June to October 2007 to assess the development of mature fouling communities. Settlement of fouling organisms largely occurred during 2 seasonal phases. Early summer (May to July) was dominated by settlement of hydroids and bivalve molluscs; late summer and early fall (August to September) was dominated by ascidian settlement. Overall, ascidians accounted for ∼50–80% of total settlement. The solitary ascidian Ciona intestinalis dominated mature fouling panels, but had low and intermittent settlement levels. The invasive colonial ascidian Didemnum vexillum settled later in the year (starting at the end of July) than other taxa. Specific knowledge of settling patterns of biofouling organisms may provide growers with a means of determining opportune times for deployment of gear to avoid excess fouling.

Nuclear Fuel, Cladding, and the “Discovery” of Zirconium

Zirconium cladding played an important role in both the Fukushima and TMI accidents. As nuclear reactors increased in size and power, metallic cladding materials were needed to protect fuel elements. Initially, aluminum and stainless steel were used, but neither of these materials is ideal for use in the high temperature, high radiation environments of nuclear reactors. Zirconium was identified as a potential “miracle” cladding material because it maintains its characteristics at high temperatures and is very corrosion resistant. At 0.185 b, zirconium also has a very low neutron absorbing cross-section. Unfortunately, zirconium is not perfect. At very high temperatures, zirconium reacts with steam to generate heat and to produce hydrogen gas. Both of these attributes can have major negative impacts during nuclear emergencies.

Initial Outbreak Period (December 2013–May 22, 2014)

The 2013–2016 Ebola outbreak began in a small Guinean village. A 2-year-old boy contacted Ebola, most likely after coming into contact with free-tailed bats, possibly by playing with them. The epidemiology of the outbreak initially followed the course of previous Ebola outbreaks. A small number of people were infected and local officials and international aid agencies worked to identify and isolate patients. Significant concern was raised when Ebola cases began to appear in Guinea’s capital, Conakry, and in the neighboring country of Liberia. The disease was also thought to have spread to Sierra Leone, although no positive samples were collected from that country. By the middle of May 2014, it appeared that the outbreak had run its course. No new cases had been seen for some time, and all known patients had either recovered or died. What was not known was that undetected transmission chains remained. Ebola continued to spread, helped by local customs such as traditional burial practices where the body of the deceased is washed and touched. The stage was set for the rapid expansion of Ebola that would occur in the late spring and early summer of 2014.

Beginning of the Decline (November–December 2014)

In November and December 2014, the Ebola outbreak began to follow different paths in different countries. Liberia experienced a significant drop in cases. The apparent declines seen in Liberia in October 2014 were real. Hospitals that were once filled beyond capacity now had only a few cases. By November 13, 2014, conditions had improved so much that Liberia let its state of emergency expire. In Guinea, caseloads remained relatively stable. Sierra Leone became the epicenter of the outbreak. During November 2014, case numbers in Sierra Leone rapidly increased and the disease reached parts of the country that had not yet been affected. Sierra Leone’s healthcare system was hard-hit. By December 14, 2014, 12 Sierra Leone doctors had been infected. In other parts of the world, the outbreak also presented a mixed picture. The outbreaks in the United States and Spain were over. In Mali, a second Ebola cluster flared up in mid-November. Ebola reached Scotland on December 29, 2014. Despite the increasing number of cases in Sierra Leone and the intermittent sparks around the world, healthcare officials began to think the worst of the outbreak might be over. Trend lines started to point downward.

Escalation (May 23, 2014–August 31, 2014)

By the middle of May 2014, the West African Ebola outbreak appeared to be under control. Then suddenly and unexpectedly, new cases began to emerge. First as a trickle, and then as a flood, the number of confirmed and suspected cases increased rapidly. West African medical facilities did their best to cope with the outbreak. Initially they were able to handle the onrush of cases, but soon resources were stretched thin. Then doctors began to die from the disease. In some cities, corpses of Ebola victims lay in the streets. Rural areas were also hard-hit. Reporters described finding whole communities decimated by the virus. In a desperate bid to contain the outbreak, countries closed their borders and issued travel bans. Despite these efforts, Ebola continued to spread. By the end of August 2014, there were active Ebola cases in Guinea, Liberia, Sierra Leone, Nigeria, and Senegal. In addition, a small number of Western healthcare workers had become infected and been transported to the United States, Spain, and the United Kingdom for treatment. Overall, more than 3000 people had contracted Ebola. More alarmingly, the number of new cases continued to grow exponentially.

The Peak in Africa (September 2014)

By September 2014, the Ebola outbreak had overwhelmed West African healthcare systems. Treatment centers were filled beyond capacity and new centers could not be opened fast enough to deal with the increasing number of cases. Overflowing medical facilities had to turn away newly arriving infected patients. Heartbreaking scenes occurred as sick patients crisscrossed cities looking for space in treatment centers only to find that no space was available. As conditions worsened, Sierra Leone took the unprecedented step of holding a 3-day, nationwide lockdown. During the lockdown, healthcare workers visited every house in the country. They gave residents information about Ebola and looked for new cases. Levels of foreign aid remained relatively low, but efforts were beginning to ramp up. In the middle of September, the United States launched a major Ebola offensive and began to send military personnel to Liberia. On the very last day of the month, news broke that an active Ebola case had been detected in Dallas, Texas. Ebola had left Africa and arrived in a western country.

Simmering to the End (January 2015–June 2016)

By January 2015, the Ebola outbreak was clearly in decline. Liberia and Guinea both had falling caseloads. Sierra Leone had high case levels at the start of 2015, but soon these too began to fall. On March 5, 2015, Liberia released its last known Ebola patient. In mid-March 2015, Sierra Leone launched a new 3-day, nationwide lockdown to find and contain the last few cases. Things looked very positive. But then, in a pattern that would repeat itself in the coming months, a new case suddenly emerged in Liberia. The virus began to show an extraordinary ability to reemerge from undetected chains of transmission. It also became clear that the semen of survivors remained infectious long after the survivors had recovered. In October 2015, a frightening new twist occurred when a UK Ebola survivor developed Ebola-related meningitis almost 9 months after she had recovered from the disease. Despite numerous setbacks and flare-ups, the West African Ebola outbreak was declared officially over on January 14, 2016. Sadly, the very next day – January 15, 2016 – a new Ebola case was detected in Sierra Leone. New cases then began to emerge in Guinea and Liberia. Another round of containment and contact tracing commenced. Finally, by June 9, 2016, all of the new cases had resolved and the 2013–2016 outbreak came to an end.

Global Spread (October 2014)

As the Ebola outbreak continued to rage in West Africa, Western countries began to be directly affected by the disease. On the last day of September 2014, the first active Ebola case was diagnosed in the United States. Officials in Dallas, Texas, scrambled to contain the virus. A few weeks later, tension rose dramatically when two of the nurses who treated the initial US patient developed Ebola. One of the nurses traveled to Ohio and back before becoming sick. She flew by plane and had contact with other travelers. Officials were very worried that Ebola flare-ups would start to occur across the country. On October 6, 2014, a nursing assistant in Spain was diagnosed with Ebola. Like the US nurses, she had helped treat a repatriated Ebola victim. On October 23, 2014, a new US case was identified. A doctor was diagnosed with Ebola in New York City after returning from Guinea. On the same day, an Ebola case was discovered in the West African country of Mali. The Ebola outbreak seemed out of control and poised to start a major international epidemic. In West Africa, however, a corner had been turned. Healthcare efforts had shifted from treating all Ebola patients in medical facilities to providing families with supplies to take care of sick patients at home. Toward the end of October 2014, reports started to surface about there being fewer cases in West Africa, especially in Liberia. These reports were initially treated with caution. As time progressed, however, it became clear that the drop in cases was real.

Why Boiling Water

The initial US reactor development program was led by the Atomic Energy Commission (AEC), the US Navy, and several major corporate organizations (GE, Westinghouse, and others). Together, these agencies produced the PWR reactors after they helped transition the US Navy submarine force from diesel-electric boats to nuclear powered entities. The technology developed during this time also set the stage for post-war commercial nuclear power plants. The BWR reactor advanced through various development stages at Argonne and in its early semicommercial operations at various sites throughout the US. Ultimately, the BWR became the second most popular reactor style in the US and the world.