Question

英文翻译，高手200分送！

要求：1。句子一定通顺，完整！
2。因为问题补充只能输入3000字节，空间不够，所以用“送翻译”来把要翻的文章发上来，见凉！
3。这是一篇生物学科的文章截选，但专业性不强的，望细心翻译，若满意有追加分100！
请注意第一点，句子通顺，谁不会用金山词霸呀

Answer 1

微波辐射的作用在Bacillus-subtilis 对微波辐射的用途为细菌杀害特别要求为医院废物的孢子介绍(Pellerin 1994 的绝育年; Tata 和Beone 1995 年; Atwater 等1997 年; Sasaki 等1998.a) 和工业食品加工(邓・等1990 年; Wang 1993 年; Sato ・等1996 年; Kozempel 等。1997 年; Kuchma 1997 年; Pagan ・等1998 年; Vaid 和主教1998) 由于它的低成本。医院废绝育是增加重要性的问题并且各种各样的有效绝育规程当前被使用, 譬如stoving, 高压蒸和辐照区域以紫外或c 光芒。传统焚秽炉是非常昂贵的, 特别当使用与越来越严密反空气污染标准符合; 电子束要求极端昂贵的机械, 并且绝育设备使用c 光芒来源严密地被调控为安全和控制克制。在工业食品加工, 微波能量使用对和消炎食物加热杀菌在短时间比较常规方法(Heddleson 等1996 年; Hammad 1998 年; Aziz 等。2002). 所以, 微波辐射被认为一个合法的供选择的方法为杀害细菌由于它的有效率、商业可及性, 和低成本比较其它技术(吴1996 年; Pierson 和Sauer 1997 年; Sasaki 等1998b) 。虽然微波效力在微生物破坏被报告了在许多研究中, 细菌杀害实际机制未被解释得相似。二个主要矛盾的结论涌现: 一些研究员归因于杀害作用由微波施加对波浪引起的热(Yeo 和al. 1999), 当其他人提出一个nonthermal 作用由于微波能量(巴恩斯和Ho 1977 年; Salvatorelli 等1996 年; 吴1996) 。仍然演讲是是否微波辐射(作为一个电磁场, E 领域) 独立地影响生物分子和结构细胞组分汇编化学热量作用由波浪引起。缺乏规范化的实验性情况提供样品曝光对一个被定义的和恒定的微波E 领域对辩论贡献了。的确, 涂药器最频繁地被使用对kill/inactivate 细菌以微波是多重状态的发电器(巴恩斯和Ho 1977 年; Salvatorelli 等1996), 相似与微波炉。这些设备有几内在不利, 主要不均匀的发行, 及时和在空间, 微波E 领域在金属封入物里面。而且, 他们不允许或温度或强度的准确E 领域的测量和方向在与样品的接近度。所以, 商业设备不是充分的为E 领域的强度的决心并且的微波应用时间期间那带领完成微生物钝化作用。这数据是内在微生物学的重要和是根本的为废物或食物绝育植物设计根据微波辐射。单模, nonresonant 波导管涂药器此中被描述允许一致并且微波E 领域和温度价值的可测量的发行适用了于细菌样品被获得。这个设备被使用暴露Bacillus-subtilis 孢子于E 领域, 很好被定义两个在高度和方向, 为几间隔时间。孢子生存被服从对微波辐射与那比较登记在常规热化以后。孢子损伤被两种治疗导致由测量调查了由电子显微镜术和数量dipicolinic 酸(DPA) 被被对待的孢子发布。材料和方法微波用具设备被修建了从标准长方形波导管和同轴组分(图1) 与磁控管摆动器被装备以向前和被反射的力量显示(100 W 最大连续波输出了力量在2□5 千兆赫) 作为微波的来源。一支长方形波导管(7□? 3□cm) 被连接了到其它相同适配器通过一个黄铜波导管平直的部分被设计拿着6 毫米(外面直径)?4 毫米(内在直径)?66 毫米(长度) 玻璃试管为装载用细菌样品(图1a) 。管的轴做了角度30 度以E 领域(图1b 的) 传播的方向; 这样配置使能微波的传播对试管被安置入波导管, 以被反射的力量不大于8% 输入功率。一台双重残余部分条频器被使用减少不需要的力量反射返回到磁控管来源。微波开关有女士几10s 的开关时光, 如此允许微波力量脉冲的应用为选择的时间期间。二小空的硼硅酸盐玻璃球形(4 毫米外面直径) 被介绍了入试管和被拿着对底部由卷起, thinwalled 聚四氟乙烯(polytetrafluorethylene, PTFE) 管(0□毫米直径?50 毫米), 防止样品流出在煮沸期间(图1.c) 。试管被关闭了与PTFE 停止者以1 毫米直径孔。温度在试管里面被测量了与一个光纤温度计被校准在各次测量之前。这个传感器有0□_C 的决议, 大约0□s 的反应时间在水中, 和由强烈的微波E 领域不心绪不宁。以这个设定, 微波Efield 向样品被申请能由量热法测量容易地确定。一个商业多重状态的烤箱, 以34□内部容量? 34? 23 cm 和有名无实的运作的力量750 W 在2□5 千兆赫, 并且被使用了为比较。在商业烤箱, 需时为水溶液到达煮沸的温度由安置测量了试管用水被填装在五个不同任意地选择的位置, 在一个中央地点在烤箱里面。 B. subtilis 孢子孢子的准备B. subtilis ATCC 6633 被使用了在研究过程中因为他们被报告是优选的显示为微波绝育分析用试样(吴1996) 。未污染的孢子悬浮准备了在被蒸馏的水中作为早先描述(Senesi 和al. 1991), 存放在4_C, 和使用在15 天之内。被保重保证, 细菌悬浮被构成了与100% 可实行转移了入试管, 包含二硼硅酸盐玻璃球形和一支薄壁PFTE 管。试管被关闭了与PFTE 停止者, 包含一个小直径孔, 和柔和地被震动消灭气泡。样品一半微波被照耀了为几间隔时间(2, 4, 6, 8, 10, 14 和20 分钟) 。另外一半是常规地激昂为同样间隔时间由浸没在煮沸的热水锅。在各种治疗以后, 孢子悬浮及时地被浸入了入冰热水锅。实验执行了在一式三份和被重覆了五次在分开的天。被照耀的和被加热的孢子样品用蒸馏水连续地被稀释了并且100 各稀释ll 播种了在一式三份Luria-Bertani 琼脂板材。CFUs 计数了在24-h 孵出以后在37_C 。孵出为另外的24 h 导致了在CFUs (更低比0□01% 的) 数量的微不足道的增量。控制样品包含了没有接受任何治疗的孢子。

Answer 2

腊样芽孢对微波辐射效应枯草杆菌孢子 引进 利用微波辐射对生物的死 特别呼吁医院废物消毒 (1994Pellerin; 1995年,塔塔BeOne; Atwater东Al. 1997年; Al实观. 1998A)及食品加工工业(邓 Al网站. 1990年; 王1993; 佐藤观Al. 1996年; AlKozempel网站. 1997年; 库奇马1997年; 谁都有Al. 1998年; Vaid和主教 1998),因为其成本低. 医院消毒是浪费 问题越来越重要,各种各样 目前使用有效消毒程序, 作为stoving、高压蒸与辐射 紫外线或C-兴业. 很传统焚化炉 昂贵的,特别是当使用按照 越来越严格的反空中排放标准; 电子 束机制,需要极为昂贵,消毒 C设备利用光来源严格规范 出于安全和控制的限制. 食品加工业、 微波和精力用于pasteurize 食物消毒比常规更短的时间内 方法(AlHeddleson网站. 1996年; 1998哈玛迪; AzizAl品牌. 2002). 因此,微波辐射被视为有效 其他方法杀死细菌,因其 功效,提供商业、成本比较低 与其它技术(1996吴; 皮尔逊和冲锋枪 1997年; Al实观. 1998b). 虽然效力于微波破坏微生物 据报道,许多研究,真正的机制 没有杀死细菌的解释 一样. 结论出现两大矛盾:有些 研究者认为杀害微波施加影响 浪潮产生的热量(Al远先生. 1999),有的 由于微波作用提出了能源本身nonthermal (合班礼士,1977年; AlSalvatorelli网站. 1996年; 吴1996). 有待解决的是微波辐射(作为 电磁场、电子领域)的影响化学 分子生物学、细胞结构组装 独立组件的热效应产生 由波. 缺乏实验条件标准化 提供样品暴露了界定,并不断 微波电子领域的辩论有所贡献. 事实上, 最常用的杀虫害/细菌活跃 同是微波多模发电机(何班礼士 1977年; AlSalvatorelli网站. 1996)、微波炉相似. 这种装置有一些固有的缺点,主要是 nonuniform的分配,在时间和空间的 微波电子领域内的金属附件. 此外, 他们不容许任何的精确测量 温度、强度和方向的电子领域 靠近样品. 因此,商业设施 没有足够的决心加大电子领域 与时间长短的微波应用,从而导致 微生物完全撤销. 这些数据内在 微生物是重要的,对于设计 食品厂的消毒和废物微波 辐射. 单模式,描述nonresonantwaveguide泡 这里可以衡量的统一和分配 双方微波电子领域的温度值 适用于细菌样本获得. 这个装置 利用枯草杆菌孢子菌,使电子领域,并 无论在规模和方向明确,几时间 间隔. 孢子的生存受到微波 辐射比常规注册后 取暖. 孢子的破坏引起了治疗 被调查的电子显微镜研究室和测量 数量(政治部)发表dipicolinic酸治疗孢子. 材料和方法 微波仪器 该装置由标准的长方形建筑 自动探测和组件(附图1), 振荡器配备了磁放大器指标 反映电力(W100最大连续波 2æ45输出功率在3.5千兆赫)的微波源的. 长方形waveguide(7æ2-3æ4教师)连接 另一个同样透过铜管接头 waveguide直节进行测试玻璃 管道600毫米-4毫米(外直径)(内直径) -66厘米(长)与细菌样本量 (附图1A). 轴心的角度作了管道30 学位与传播方向的电子领域 (附图1B); 这种格局使繁殖 微波的试管纳入waveguide, 有反映权不得超过8%的投入 电力. 双调谐存根是用来减少意外 返回磁放大器思考能力的来源. < 微波开关有开关时间10s余数, 从而使权力运用脉冲微波 选定合适的时间. 两个小空borosilicate 玻璃球(直径4厘米外)引入 测试管子的底部,并举行座,thinwalled 尺寸(polytetrafluorethylene,TFE)映管(六0Æ9 直径50-六),以防止在样品流出 童心(附图1C). 测试管道关闭,TFE Stoppers有直径1毫米的洞. 温度 在测试管是衡量一个光纤 每次校准温度计测量. 本 已解决0æ1_c传感器,反应时间约 0æ2的水,而不是紧张不安 微波电子领域. 这个成立,微波Efield 可应用于样品的确定容易 热测量. 商业多模 烘箱、有能力的国内教师和34æ5-34-23 象征工作能力的2æ45W750千兆赫,还 用于比较. 在商业微波炉,时间 所需解决水汽达到沸点 温度测量试验,将补管 水五种随机位置, 中央位置在烘箱. B枯草杆菌孢子准备 B孢子的枯草杆菌ATCC在6633年使用 研究报告所要优化指标 分析微波消毒(吴1996). 污染 孢子中断编写的蒸馏水 先前(AlSenesi网站. 1991),存放在4_c, 并在15天内使用. 注意保证 细菌中断与100%是可行 被转移到管测试,其中两 borosilicate玻璃幕墙PFTE领域和细管. 测试与PFTEStoppers管道关闭,其中 小直径孔,都动摇着消除空气 泡沫. 一半的样本是微波辐射 若干时间间隔(2、4、6、8、10、14和20分). < 另一半是传统加热的同时 沉浸在水中的间隔浴池. 每次 治疗孢子迅速陷入了中断 冰水浴. 实验进行式 5天时间,反复在不同. 辐照、 加热孢子样本与蒸馏水稀释系列 水稀释,分别是11号种子、100式三份 在Luria-Bertani中部板块. 会后,被CFUs 24-H37_c在孵化. 另外孵化24H 导致轻微增加CFUs(下 0æ001比%). 控制样品中孢子没有 接受任何治疗.

Answer 3

微波放射线因为它的低成本而被用来对医院废物的灭菌消毒(Pellerin 1994;
Tata and Beone 1995; Atwater et al. 1997;Sasaki et al. 1998a) 和工业食品加工 。
(Denget al. 1990; Wang 1993; Sato et al. 1996; Kozempel et al.1997; Kuchma 1997;
Pagan et al. 1998; Vaid and Bishop1998)。现在医院废物的消毒这一问题变的越来
越为重要，消毒的方法也各种各样, 比如用紫外线或γ-射线来做的火炉温烤法,
高压蒸发法和放射线治疗法。 传统的焚烧装置非常的贵, 特别当使用与越来越
严密反空气污染标准符合; 电子束要求极端昂贵的机械, 并且严密地调控为安全
控制消毒设备使用γ-射线来源。 在工业的食品加工中, 微波能源用来进行低温
杀菌和传统短时间内食物消毒 (Heddleson 以及其他人；1996; Hammad 1998;
Aziz 以及其他人 2002)。由于微波放射线与其他灭菌方法相比，它的效力，商
业效益和较低的费用都好于其他技术(Wu 1996; Pierson 和 Sauer 1997; Sasaki
以及其他人。 1998b). 所以, 微波辐射被认为是杀害细菌的一个合法的供选择
的方法。
虽然微电波对微生物的破坏在许多研究中有报告, 但其灭菌的机制没有一个统一的说法，一些研究员将其归于热效应使其死亡 (Yeo 以及其他人。 1999), 另一些人则认为是由于微波能源本身的效果（巴恩斯和Ho 1977 年; Salvatorelli 等1996 年; 吴1996）。仍然有人质疑微波辐射(一个电磁场, 电子领域)是否独立地影响着生物分子和结构细胞组分。缺乏规范化的实验性情况提供样品暴露的实验给定义微波电子和持续微波电子仍在辩论。 当然，微电波是过去杀死细菌或钝化细菌活性的是多模态产生器（(Barnes and Ho1977; Salvatorelli et al. 1996)）, 类似微波炉。这些装置有一些本质的缺点, 主要是在微波电子领域金属制的附件内，时间和空间的不均匀分配。 而且, 他们不能够对样品进行测量温度或强度的测量，也不能够对样品中电子的跑向进行准确的测量。 因此, 对于电子领域的商界们，他们对其装置的研发投入没有强烈的决心， 这就无法使微波作用于微生物这个领域快速发展起来。 这些数据是对反映微生物本质的重要作用和对设计以微波放射线为基础的废物或食物消毒厂的基本依据。
单一模态，非谐振的的波导施力器用来测量在微波电子领域上和适用于细菌的样品的温度上得到了了一致。 过去这一个装置是用于户外射线对枯草杆菌孢子作用，在微波辐射后生存下来的枯草杆菌孢子与传统受热后的相比，振幅和方向都得到了确定。通过对在电子显微镜下观察枯草杆菌孢子的损害和测量释放出的啶二羧酸（DPA）的数量，发现细菌的损害减少了。

Answer 4

Effect of microwave radiation on Bacillus subtilis spores

INTRODUCTION
The use of microwave radiation for bacterial killing is
particularly appealing for sterilization of hospital waste
(Pellerin 1994; Tata and Beone 1995; Atwater et al. 1997;
Sasaki et al. 1998a) and industrial food processing (Deng
et al. 1990; Wang 1993; Sato et al. 1996; Kozempel et al.
1997; Kuchma 1997; Pagan et al. 1998; Vaid and Bishop
1998) because of its low cost. Hospital waste sterilization is a
problem of increasing importance and a wide variety of
efficacious sterilization procedures are currently used, such
as stoving, high-pressure steaming and irradiation with
ultraviolet or c-rays. Traditional incinerators are very
expensive, particularly when used in accordance with the
increasingly stringent anti-air-pollution standards; electron
beams require extremely expensive machinery, and sterilization
equipment using c-ray sources is strictly regulated
for safety and control restraints. In industrial food processing,
microwave energy has been used to pasteurize and
sterilize food in a shorter time compared with conventional
methods (Heddleson et al. 1996; Hammad 1998; Aziz et al.
2002). Therefore, microwave radiation is regarded as a valid
alternative method for killing bacteria because of its
effectiveness, commercial availability, and lower cost compared
with other technologies (Wu 1996; Pierson and Sauer
1997; Sasaki et al. 1998b).
Although the efficacy of microwaves in microbial destruction
has been reported in many studies, the actual mechanism
of bacterial killing has not been interpreted in the
same way. Two main conflicting conclusions emerge: some
researchers attribute the killing effect exerted by microwaves
to the heat the waves generate (Yeo et al. 1999), while others
propose a nonthermal effect due to microwave energy itself
(Barnes and Ho 1977; Salvatorelli et al. 1996; Wu 1996).
Still to be addressed is whether microwave radiation (as a
electromagnetic field, E-field) influences the chemistry of
biological molecules and the assembly of structural cell
components independently of the thermal effect generated
by waves. The lack of standardized experimental conditions
providing exposure of samples to a defined and constant
microwave E-field has contributed to the debate. Indeed, the
applicators most frequently used to kill/inactivate bacteria
with microwaves are multimode generators (Barnes and Ho
1977; Salvatorelli et al. 1996), similar to microwave ovens.
These devices have several intrinsic disadvantages, primarily
the nonuniform distribution, in time and in space, of the
microwave E-field inside the metal enclosure. Moreover,
they do not allow accurate measurements of either the
temperature or the intensity and direction of the E-field in
proximity to the samples. Therefore, commercial devices are
not adequate for determination of the intensity of the E-field
and the time-duration of microwave application that leads to
complete microbial inactivation. These data are of intrinsic
microbiological importance and are essential for the design
of waste or food sterilization plants based on microwave
radiation.
The single-mode, nonresonant waveguide applicator described
herein allowed a uniform and measurable distribution
of both the microwave E-field and the temperature value
applied to bacterial samples to be obtained. This device was
used to expose Bacillus subtilis spores to an E-field, well
defined both in amplitude and direction, for several time
intervals. The survival of spores subjected to microwave
radiation was compared with that registered after conventional
heating. The spore damage induced by both treatments
was investigated by electron microscopy and by measuring the
amount of dipicolinic acid (DPA) released by treated spores.
MATERIALS AND METHODS
Microwave apparatus
The device was constructed from standard rectangular
waveguides and coaxial components (Fig. 1) with a
magnetron oscillator equipped with indicators of forward
and reflected power (100 W of maximum continuous wave
output power at 2Æ45 GHz) as the source of the microwaves.
A rectangular waveguide (7Æ2 • 3Æ4 cm) was connected
to another identical adapter through a brass
waveguide straight section designed to hold a glass test
tube of 6 mm (outer diameter) •4 mm (inner diameter)
•66 mm (length) for loading with bacterial samples
(Fig. 1a). The axis of the tube made an angle of 30
degrees with the direction of propagation of the E-field
(Fig. 1b); such a configuration enabled the propagation of
microwaves to the test tube placed into the waveguide,
with a reflected power not greater than 8% of the input
power. A double stub tuner was used to reduce unwanted
power reflections returning to the magnetron source. The
microwave switch had a switching time of a few 10s of ms,
thus allowing the application of microwave power pulses
for selected time durations. Two small empty borosilicate
glass spheres (4 mm outer diameter) were introduced into
the test tubes and held to the bottom by a coiled, thinwalled
teflon (polytetrafluorethylene, PTFE) tube (0Æ9 mm
diameter •50 mm), to prevent outflow of samples during
boiling (Fig. 1c). The test tubes were closed with PTFE
stoppers with a 1-mm diameter hole. The temperature
inside the test tubes was measured with a fibre-optic
thermometer calibrated before each measurement. This
sensor has a resolution of 0Æ1_C, a response time of about
0Æ2 s in water, and is not perturbed by the intense
microwave E-field. With this set-up, the microwave Efield
applied to samples could be determined easily by
calorimetric measurements. A commercial multimode
oven, with an internal capacity of 34Æ5 • 34 • 23 cm and
a nominal working power of 750 W at 2Æ45 GHz, was also
used for comparison. In the commercial oven, the time
required for aqueous solutions to reach the boiling
temperature was measured by placing the test tubes filled
with water in five different randomly selected positions, in
a central location inside the oven.

Preparation of B. subtilis spores
Spores of B. subtilis ATCC 6633 were used throughout the
study as they are reported to be optimal indicators for
microwave sterilization assays (Wu 1996). Uncontaminated
spore suspensions were prepared in distilled water as
previously described (Senesi et al. 1991), stored at 4_C,
and used within 15 days. Care was taken to ensure that the
bacterial suspensions were constituted with 100% viable
were transferred into test tubes, which contained two
borosilicate-glass spheres and a thin walled PFTE tube.
Test tubes were closed with PFTE stoppers, containing a
small-diameter hole, and were gently shaken to eliminate air
bubbles. One half of the samples was microwave-irradiated
for several time intervals (2, 4, 6, 8, 10, 14 and 20 min). The
other half was conventionally heated for the same time
intervals by immersion in a boiling water bath. After each
treatment, spore suspensions were promptly plunged into an
ice water bath. Experiments were performed in triplicate
and repeated five times on separate days. Irradiated and
heated spore samples were serially diluted with distilled
water and 100 ll of each dilution was seeded in triplicate
onto Luria-Bertani agar plates. CFUs were counted after a
24-h incubation at 37_C. Incubation for an additional 24 h
led to a negligible increase in the number of CFUs (lower
than 0Æ001%). Control samples contained spores that did not
undergo any treatment.

Answer 5

Effect of microwave radiation on Bacillus subtilis spores

INTRODUCTION
The use of microwave radiation for bacterial killing is
particularly appealing for sterilization of hospital waste
(Pellerin 1994; Tata and Beone 1995; Atwater et al. 1997;
Sasaki et al. 1998a) and industrial food processing (Deng
et al. 1990; Wang 1993; Sato et al. 1996; Kozempel et al.
1997; Kuchma 1997; Pagan et al. 1998; Vaid and Bishop
1998) because of its low cost. Hospital waste sterilization is a
problem of increasing importance and a wide variety of
efficacious sterilization procedures are currently used, such
as stoving, high-pressure steaming and irradiation with
ultraviolet or c-rays. Traditional incinerators are very
expensive, particularly when used in accordance with the
increasingly stringent anti-air-pollution standards; electron
beams require extremely expensive machinery, and sterilization
equipment using c-ray sources is strictly regulated
for safety and control restraints. In industrial food processing,
microwave energy has been used to pasteurize and
sterilize food in a shorter time compared with conventional
methods (Heddleson et al. 1996; Hammad 1998; Aziz et al.
2002). Therefore, microwave radiation is regarded as a valid
alternative method for killing bacteria because of its
effectiveness, commercial availability, and lower cost compared
with other technologies (Wu 1996; Pierson and Sauer
1997; Sasaki et al. 1998b).
Although the efficacy of microwaves in microbial destruction
has been reported in many studies, the actual mechanism
of bacterial killing has not been interpreted in the
same way. Two main conflicting conclusions emerge: some
researchers attribute the killing effect exerted by microwaves
to the heat the waves generate (Yeo et al. 1999), while others
propose a nonthermal effect due to microwave energy itself
(Barnes and Ho 1977; Salvatorelli et al. 1996; Wu 1996).
Still to be addressed is whether microwave radiation (as a
electromagnetic field, E-field) influences the chemistry of
biological molecules and the assembly of structural cell
components independently of the thermal effect generated
by waves. The lack of standardized experimental conditions
providing exposure of samples to a defined and constant
microwave E-field has contributed to the debate. Indeed, the
applicators most frequently used to kill/inactivate bacteria
with microwaves are multimode generators (Barnes and Ho
1977; Salvatorelli et al. 1996), similar to microwave ovens.
These devices have several intrinsic disadvantages, primarily
the nonuniform distribution, in time and in space, of the
microwave E-field inside the metal enclosure. Moreover,
they do not allow accurate measurements of either the
temperature or the intensity and direction of the E-field in
proximity to the samples. Therefore, commercial devices are
not adequate for determination of the intensity of the E-field
and the time-duration of microwave application that leads to
complete microbial inactivation. These data are of intrinsic
microbiological importance and are essential for the design
of waste or food sterilization plants based on microwave
radiation.
The single-mode, nonresonant waveguide applicator described
herein allowed a uniform and measurable distribution
of both the microwave E-field and the temperature value
applied to bacterial samples to be obtained. This device was
used to expose Bacillus subtilis spores to an E-field, well
defined both in amplitude and direction, for several time
intervals. The survival of spores subjected to microwave
radiation was compared with that registered after conventional
heating. The spore damage induced by both treatments
was investigated by electron microscopy and by measuring the
amount of dipicolinic acid (DPA) released by treated spores.
MATERIALS AND METHODS
Microwave apparatus
The device was constructed from standard rectangular
waveguides and coaxial components (Fig. 1) with a
magnetron oscillator equipped with indicators of forward
and reflected power (100 W of maximum continuous wave
output power at 2Æ45 GHz) as the source of the microwaves.
A rectangular waveguide (7Æ2 • 3Æ4 cm) was connected
to another identical adapter through a brass
waveguide straight section designed to hold a glass test
tube of 6 mm (outer diameter) •4 mm (inner diameter)
•66 mm (length) for loading with bacterial samples
(Fig. 1a). The axis of the tube made an angle of 30
degrees with the direction of propagation of the E-field
(Fig. 1b); such a configuration enabled the propagation of
microwaves to the test tube placed into the waveguide,
with a reflected power not greater than 8% of the input
power. A double stub tuner was used to reduce unwanted
power reflections returning to the magnetron source. The
microwave switch had a switching time of a few 10s of ms,
thus allowing the application of microwave power pulses
for selected time durations. Two small empty borosilicate
glass spheres (4 mm outer diameter) were introduced into
the test tubes and held to the bottom by a coiled, thinwalled
teflon (polytetrafluorethylene, PTFE) tube (0Æ9 mm
diameter •50 mm), to prevent outflow of samples during
boiling (Fig. 1c). The test tubes were closed with PTFE
stoppers with a 1-mm diameter hole. The temperature
inside the test tubes was measured with a fibre-optic
thermometer calibrated before each measurement. This
sensor has a resolution of 0Æ1_C, a response time of about
0Æ2 s in water, and is not perturbed by the intense
microwave E-field. With this set-up, the microwave Efield
applied to samples could be determined easily by
calorimetric measurements. A commercial multimode
oven, with an internal capacity of 34Æ5 • 34 • 23 cm and
a nominal working power of 750 W at 2Æ45 GHz, was also
used for comparison. In the commercial oven, the time
required for aqueous solutions to reach the boiling
temperature was measured by placing the test tubes filled
with water in five different randomly selected positions, in
a central location inside the oven.

Preparation of B. subtilis spores
Spores of B. subtilis ATCC 6633 were used throughout the
study as they are reported to be optimal indicators for
microwave sterilization assays (Wu 1996). Uncontaminated
spore suspensions were prepared in distilled water as
previously described (Senesi et al. 1991), stored at 4_C,
and used within 15 days. Care was taken to ensure that the
bacterial suspensions were constituted with 100% viable
were transferred into test tubes, which contained two
borosilicate-glass spheres and a thin walled PFTE tube.
Test tubes were closed with PFTE stoppers, containing a
small-diameter hole, and were gently shaken to eliminate air
bubbles. One half of the samples was microwave-irradiated
for several time intervals (2, 4, 6, 8, 10, 14 and 20 min). The
other half was conventionally heated for the same time
intervals by immersion in a boiling water bath. After each
treatment, spore suspensions were promptly plunged into an
ice water bath. Experiments were performed in triplicate
and repeated five times on separate days. Irradiated and
heated spore samples were serially diluted with distilled
water and 100 ll of each dilution was seeded in triplicate
onto Luria-Bertani agar plates. CFUs were counted after a
24-h incubation at 37_C. Incubation for an additional 24 h
led to a negligible increase in the number of CFUs (lower
than 0Æ001%). Control samples contained spores that did not
undergo any treatment.