Medical scientists have high hopes for plasmas. Produced in electrical discharges, these gases of free electrons and ions have already been shown to destroy pathogens, help heal wounds, and selectively kill cancer cells. No one is exactly sure how all of this works, but it seems that plasmas generate so-called reactive oxygen species in the air. These highly reactive molecules, which are present in our own immune system, oxidize cell membranes and damage DNA.
医学科学家们对等离子体寄予厚望。这些由放电过程产生的游离电子和离子的气体，已被证明能杀灭病原体、促进伤口愈合和选择性地杀死癌细胞。没有人完全知道这种事实是如何进行的，但它似乎是等离子体在空气里产生的所谓活性氧的作用。我们的免疫系统中，也存在着这些高活性分子，氧化细胞膜和损伤DNA�?br />
Plasma devices are already undergoing clinical testing to see whether they are safe to use. But these prototypes are limited: Either they need an external power source to generate the many kilovolts required for the electrical discharge, or they need an external gas supply and regulation to sustain the plasma. Such drawbacks make it difficult to use the devices in the field for emergency calls, natural disaster responses, or military operations.
等离子体装置已在进行临床试验，观察它们是否可以安全使用。但这些原型是有局限性的：或者它们需要一个外部电源，以产生放电所要求的许多千伏的电压，或者它们需要一个外部的气源和调节维持等离子体。由于这些弊端，使这种装置在紧急呼叫、自然灾害反应或军事行动等现场中难以使用�?br />
A group led by engineer Xinpei Lu at the Huazhong University of Science and Technology in China believes it has a device with none of these drawbacks. Powered by a normal 12-volt battery and operating in open air without a gas supply, the prototype, which they call a plasma flashlight, should be portable enough to take anywhere. "It generates the plasma even being disconnected from wall power, even using very low power," says group member Kostya Ostrikov of CSIRO Materials Science and Engineering in Lindfield, Australia.
中国华中科技大学鲁培新领导的团队，认定他们的装置没有这些缺点。他们称之为等离子体手电筒的原型，由普通的12伏电池作为能源，在开放的空气中运作不需要气源，便携式的将可以在任何地方使用。团队成员、位于林德菲尔德的澳大利亚联邦科学和技术研究组织（CSIRO）材料科学和工程分部的卡斯铁�?bull;阿斯确里卡夫（Kostya Ostrikov）说�?ldquo;这种装置即使不与墙上的电源连接，即使用很低的功率，它也会产生等离子体�?rdquo;
#p#副标�?e#The flashlight's battery is far too small to create a plasma on its own, so the researchers use a common electronic device known as a DC booster to step up the voltage to 10 kilovolts. One output of the booster is wired to the device's shell—or "grounded," in technical speak—while the other goes to an array of 12 fine, stainless steel needles that create a rapidly pulsing electrical discharge. The circuit has several "ballast" resistors that limit the discharge's current so that the flashlight is safe to touch.
手电筒的电池实在太小，以致它自己是远远不能产生等离子体的，所以研究人员采用一种称为直流助推器的电器，把它的一条输出线连接到装置的壳上——用技术语言来说�?ldquo;接地”——而其他的接到一个由12根精细不锈钢针组成的阵列上，这样就形成了一个快速脉冲放电装置。电路中有几�?ldquo;压载”电阻限定放电的电流，因此手电筒是可以安全触摸的�?br />
To test the device, Lu's group grew thick films of Enterococcus faecalis, bacteria that are well-known to infect root canals in the mouth and are highly resistant to both heat and antibiotics. The researchers used some of the so-called biofilms as control samples and subjected the others to the plasma flashlight for 5 minutes at a distance of 5 millimeters. Afterward, they marked all the samples with two fluorescent solutions: a green one that flagged living cells, and a red one that flagged dead cells.
为了测试装置，鲁的团队培养了厚膜粪肠球菌，众所周知，该菌能感染口腔中牙齿的根管，并既具有高度的抗热性，又具有对抗菌素高度的抗药性。研究人员采用了一些称为生物膜的作为对照样本，以及另外的试验样本，接受等离子体电筒�?米远的距离照�?分钟。随后，他们�?种荧光溶液标记所有的样本：活细胞被绿色荧光溶液标记，死细胞被红色荧光溶液标记�?br />
#p#副标�?e#The team found that the control samples stayed green, while the treated samples had turned almost completely red—even at the bottom of the biofilms, which were about 17 cells deep. The results, which are published online today in the Journal of Physics D: Applied Physics, were even better than a nonportable plasma device that Lu's group had tested previously.
该团队发现，对照样本全部保持绿色，而试验样本几乎完全转变为红色——甚至在生物膜下约17个细胞厚度的底层球菌也染为红色。这些结果，已在线发表于2012�?�?日的《物理学杂志D辑：应用物理学》，等离子体手电筒甚至还优于鲁团队先前已试验过的非便携式等离子体装置�?br />
Making the device truly portable is a big advance, says Michael Keidar, a plasma physicist at George Washington University in Washington, D.C. "Operating cold plasma in air is challenging, [and] it seems like they were able to make it work," he says. "This is a purely technical issue that was solved."
位于华盛顿的乔治•华盛顿大学等离子体物理学家迈克尔•凯达（Michael Keidar）认为，使这种装置真正地便携是一个很大的进展。他说：“在空气中运用冷等离子体是具有挑战性的，好象他们能使这一装置工作。这解决的，纯粹是一个技术问题�?rdquo;
Engineer Miran Mozetič of the Jožef Stefan Institute in Ljubljana, Slovenia, points out another advantage of the plasma flashlight: It uses only a meager 60 milliwatts per discharge. "This is an important fact because it indicates that the battery [will] not have to be exchanged or refilled frequently," he says.
位于斯洛文尼亚的卢布尔雅那市约瑟�?bull;斯特凡研究所的工程师米朗•毛斯甲迪（Miran Mozetič ）指出，等离子体手电筒另外的优点：它每次放电仅耗用微量�?0毫瓦电。他说：“这是一个重要的事实，因为这表明，它的电池将没有必要经常替换或充电�?rdquo;
Like any other medical device, the plasma flashlight will have to go through rigorous clinical testing. But Ostrikov says that, besides making it smaller and optimizing its efficiency, the plasma flashlight is "pretty much" a commercial device already.
象任何其他的医疗器械一样，等离子体手电筒也必须要经过严格的临床试验。不过，阿斯确里卡夫认为，除了使这一装置更小一些和优化它的效率外，等离子体手电�?ldquo;差不�?rdquo;已经是一种可以投放市场的医疗器械商品了�?nbsp;
