Microwave Technique for Polysaccharide Extraction from Dendrobium huoshanense

The effect of material granularity, extraction times, extraction time, mi-crowave power and solid-liquid ratio on the yield of polysaccharide of Dendrobium huoshanense in microwave-assisted extraction was discussed through single factor experiment. The key factors in polysaccharide extraction and the advantages over the traditional extraction method were studied based on orthogonal experiment. The results showed that the influences became unobvious with the promotion of the fac-tor’s level. The orthogonal experiment showed that the optimal factor in the mi-crowave-assisted extraction was that the sample was extracted for four times with an extraction time of 40 min under 550 W. Al these results would lay a founda-tion for exploring a new method for the extraction of polysaccharide from Dendrobi-um huoshanense.

Preparation of Phosphors MAl_2O_4∶Eu^(2+)(M=Ca,Sr,Ba) by Microwave Heating Technique and Their Phosphorescence

The phosphors of the alkaline earth aluminates coactivated with europium and other rare earths were successfully obtained by microwave radiation heating technique.These phosphors have bright phosphorescence and maintain their afterglow for a fairly long duration.

Preparation of the Phosphors BaAl_2O_4:Eu, RE (RE=Dy, Ho) by Microwave Heating Technique and Observation of Long Phosphorescence

The phosphors BaAl2O4: Eu2+. RE (RE=Dy. Ho) have been prepared by the microwave heating technique. The long-lasting phosphorescence in the phosphors of the barium aluminate activated with europium and other rare earths has been observed for the first time.

Scavenging Microwave Wireless Power:A Unified Model,Rectenna Design Automation,and Cutting-Edge Techniques

While sufficient review articles exist on inductive short-range wireless power transfer(WPT),long-haul microwave WPT(MWPT)for solar power satellites,and ambient microwave wireless energy harvesting(MWEH)in urban areas,few studies focus on the fundamental modeling and related design automation of receiver systems.This article reviews the development of MWPT and MWEH receivers,with a focus on rectenna design automation.A novel rectifier model capable of accurately modeling the rectification process under both high and low input power is presented.The model reveals the theoretical boundary of radio frequency-to-direct current(dc)power conversion efficiency and,most importantly,enables an automated system design.The automated rectenna design flow is sequential,with the minimal engagement of iterative optimization.It covers the design automation of every module(i.e.,rectifiers,matching circuits,antennae,and dc–dc converters).Scaling-up of the technique to large rectenna arrays is also possible,where the challenges in array partitioning and power combining are briefly discussed.In addition,several cutting-edge rectenna techniques for MWPT and MWEH are reviewed,including the dynamic range extension technique,the harmonics-based retro-directive technique,and the simultaneous wireless information and power transfer technique,which can be good complements to the presented automated design methodology.

Microwave Techniques in Auriculotherapy

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Imaging-based prediction of hepatocellular carcinoma recurrence after microwave ablation as bridge therapy: A glimpse into the future

Liver transplantation(LT)remains the treatment of choice for early-stage hepato-cellular carcinoma(HCC)and offers the best long-term oncological outcomes.However,the increasing waiting list for LT has led to a significant dropout rate as patients experience tumor progression beyond the Milan criteria.Currently,locoregional therapies,such as microwave ablation(MWA),have emerged as promising bridge treatments for patients awaiting LT.These therapies have shown promising results in preventing tumor progression,thus reducing the dropout rate of LT candidates.Despite the efficacy of MWA in treating HCC,tumoral recurrence after ablation remains a major challenge and significantly impacts the prognosis of HCC patients.Therefore,accurately diagnosing tumoral recurrence post-ablation is crucial.Recent studies have developed novel imaging features based on magnetic resonance imaging of HCC,which could provide essential information for predicting early tumoral recurrence after MWA.These advancements could address this unresolved challenge,improving the clinical outcomes of patients on the LT waiting list.This article explored the current landscape of MWA as a bridge therapy for HCC within the Milan criteria,high-lighting the emerging role of novel imaging-based features aimed at improving the prediction of tumor recurrence after MWA.

Safety and efficacy of microwave ablation for periductal hepatocellular carcinoma with intraductal cooling of the central bile ducts through a percutaneous transhepatic cholangial drainage tube

Background and aims:Biliary thermal injury caused by microwave ablation(MWA)for a hepatocellular carcinoma(HCC)close to the central bile ducts always results in severe complications and leads to mortality.Some studies have demonstrated that intraductal cooling of the biliary tract with chilled saline during thermal ablation can successfully prevent these complications.In this study,we present a novel bile duct cooling technique through a percutaneous transhepatic cholangial drainage(PTCD)tube for preventing biliary thermal injury caused by MWA,and compare the feasibility and safety of the intraductal cooling technique when performed with a PTCD tube and with an endoscopic nasobiliary drainage(ENBD)tube.Methods:Participants were randomly assigned to undergo MWA of HCC with intraductal chilled saline perfusion through a PTCD tube or an ENBD tube.The main study outcomes were bile duct complications related to MWA and local tumor recurrence,p value<0.05 was considered to indicate a statistically significant difference.Results:A total of 23 patients with an HCC(23 nodules)close to a central bile duct were enrolled in this study.Of these patients,12 had a PTCD tube and 11 had an ENBD tube placed into the hepatic duct close to the lesions.There were no PTCD-and ENBD-related mortality cases.There was no complication related to the PTCD procedure;however,3 patients(27.27%)developed acute pancreatitis and 1 patient(9.09%)had hemorrhage in the ENBD group(p=0.037).One patient(8.33%)in the PTCD group had bile leakage and 2 patients(18.18%)in the ENBD group developed a biloma.Within 5 years,1 patient in the PTCD group and 2 patients in the ENBD group had local recurrence.There was no significant difference in local recurrence,nonlocal hepatic recurrence,mortality rate,or median cumulative overall survival between the 2 groups.Conclusions:The intraductal cooling technique using a PTCD tube is a feasible and effective method for preventing bile duct thermal injury caused by MWA for an HCC close to the central bile ducts.It does not increase local recurrence and may be safer than intraductal cooling through an ENBD tube.

Effectiveness of microwave endometrial ablation combined with hysteroscopic transcervical resection in treating submucous uterine myomas

BACKGROUND Hypermenorrhea is characterized by excessive menstrual bleeding that causes severe anemia and interferes with everyday life.This condition can restrict women’s social activities and decrease their quality of life.Microwave endometrial ablation(MEA)using a 2.45-GHz energy source is a minimally invasive alternative to conventional hysterectomy for treating hypermenorrhea that is resistant to conservative treatment,triggered by systemic disease or medications,or caused by uterine myomas and fibrosis.The popularity of MEA has increased worldwide.Although MEA can safely and effectively treat submucous myomas,some patients may still experience recurrent hypermenorrhea postoperatively and may require additional treatment.AIM To investigate the efficacy of MEA combined with transcervical resection(TCR).METHODS Participants underwent cervical and endometrial evaluations.Magnetic resonance imaging and hysteroscopy were performed to evaluate the size and location of the myomas.TCR was performed before MEA using a hystero-resectoscope.MEA was performed using transabdominal ultrasound.The variables included operation time,number of ablation cycles,length of hospital stay,and visual analog scale cores for hypermenorrhea,dysmenorrhea,and treatment satisfaction at 3 and 6 mo postoperatively.The postoperative incidence of amenorrhea,changes in hemoglobin concentrations,and MEA-related complications were evaluated.RESULTS A total of 34 women underwent a combination of MEA and TCR during the study period.Two patients were excluded from the study as their histopathological tests identified uterine malignancies(uterine sarcoma and endometrial cancer).The 32 eligible women(6 nulliparous,26 multiparous)had a mean age of 45.2±4.3 years(range:36–52 years).Patients reported very severe hypermenorrhea(10/10 points on the visual analog scale)before the procedure.However,after the procedure,the hypermenorrhea scores decreased to 1.2±1.3 and 0.9±1.3 at 3 and 6 mo,respectively(P<0.001).The mean follow-up duration was 33.8±16.8 mo.Although 10 women(31.3%)developed amenorrhea during this period,none experienced a recurrence of hypermenorrhea.No surgical complications were observed.CONCLUSION Reducing the size of uterine myomas by combining MEA and TCR can safely and effectively treat hypermenorrhea in patients with submucous myomas.

The Application of Laparoscopic B-Ultrasound Microwave Ablation Technology in Liver Metastasis of Colorectal Cancer

Liver is the most common metastasis target organ in the late stage of colorectal cancer. More than 50% of colorectal cancer patients will have simultaneous or heterochronous liver metastasis. The survival time of patients with colorectal cancer and liver metastasis (CRLM) is short;not all patients can get radical resection of liver metastasis. For this part of patients, microwave ablation technology has been proved to be one of the effective methods for the treatment of liver metastasis. Laparoscopic B-ultrasound ablation also highlights a lot of minimally invasive advantages;this paper reviews the relevant literature of PubMed database, Wanfang database and CNKI database, in order to provide the treatment basis for clinical application of microwave ablation technology under laparoscopic B-ultrasound in the treatment of CRLM. The results showed that the safety and effectiveness of microwave ablation for liver metastases under the location of B-ultrasonic laparoscopy were confirmed, and patients with liver metastases of colorectal cancer who could not be resected could choose this treatment.

A Rapid and Efficient Synthesis of Diaryl Thioureas via Solvent-Free Reaction Using Microwave

A rapid and efficient method for the preparation of diaryl thiourea compounds was reported for the first time. Twelve diaryl thiourea compounds that possessing biological activity have been synthesized in excellent yields (91-97%). The reaction proved to be extremely simple and highly efficient (in 1.5-4.5 min).

Effectiveness of treating menorrhagia using microwave endometrial ablation at a frequency of 2.45 GHz

BACKGROUND Microwave endometrial ablation(MEA)is a minimally invasive treatment for menorrhagia.It has been covered by the national insurance in Japan since April 2012,and its demand has been increasing as the importance of women’s health has advanced in society.AIM To examine the efficacy of MEA as a treatment option for menorrhagia.METHODS In this study,we retrospectively analyzed 76 patients who underwent MEA between January 2016 and March 2020 in our department.MEA was performed in the lithotomy position,under general anesthesia,and with transabdominal ultrasound guidance,including the entire endometrial circumference while confirming endometrial coagulation.The Microtaze AFM-712 and the Sounding Applicator CSA-40CBL-1006200C were used for MEA,and the endometrium was ablated using a Microtaze output of 70 W and coagulation energization time of 50 s per cycle.The visual analog scale(VAS)was used to evaluate menorrhagia,menstrual pain,and treatment satisfaction.Additionally,the hemoglobin(Hb)levels before and after MEA and associated complications were investigated.RESULTS The average age of the patients was 44.8±4.0 years.While 14 patients had functional menorrhagia,62 had organic menorrhagia,of whom 14 had endometrial polyps,40 had uterine fibroids,and 8 had adenomyosis.The VAS score before MEA and 3 and 6 mo after the procedure were 10,1.3±1.3,and 1.3±1.3,respectively,for menorrhagia and 10,1.3±1.8,and 1.3±1.8,respectively,for menstrual pain,both showing improvements(P<0.001).The MEA Hb level significantly improved from 9.2±4.2 g/dL before MEA to 13.4±1.2 g/dL after MEA(P=0.003).Treatment satisfaction was high,with a VAS score of 9.6±0.7.Endometritis was observed in one patient after surgery and was treated with antibiotics.CONCLUSION MEA is a safe and effective treatment for menorrhagia.

ANALYSIS OF MICROWAVE N-PORT NETWORK BY A MODIFIED BOUNDARY ELEMENT METHOD

A new approach based on resonance technique and modified boundary ele-ment method is presented to calculate the impedance parameter matrix of a microwaveN-port network of waveguide structure.A two port network is taken as a numerical ex-ample and the results show that the approach occupys the advantages of high accuracyand less computation effort.

AN IMPROVEMENT TO THE HARMONIC-BALANCE TECHNIQUE FOR ANALYZING NONLINEAR CIRCUITS

In this paper,an improved method,which is based on the harmonic-balance tech-nique,for speeding up the convergence iteration procedure is presented.As an example,it isapplied to the nonlinear analysis of microwave mixer,in which a simple time domain to fre-quency domain transformation technique for the mixer diode is firstly introduced.The use of thistechnique saves computing time dramatically.And the analyzed results are in good agreementwith the results published.The improved method can also be extended to the CAA of nonlinearcircuits with multi-devices.

Microwave Generation from an Oscillating Virtual Cathode Produced by Non-homogeneous Electron Beams

Microwave generation from a resonant cavity surrounding oscillating virtual cathode,which is produced by non-homogeneous electron beams,is studied experimentally.The microwave power is measured by using the crystal detector and frequencies are measured by using the heterodyne technique.A single microwave pulse contains two microwave signals with different frequencies,one peak power is 1.12MW at 5.03GHz and the other is 0.56MW at 5.24GHz,and their 3dB bandwidths are 18 and 25 MHz,respectively.

Structural and luminescent properties of (Eu,Tb) PO_4·H_2O nanorods/nanowires prepared by microwave technique

Nanowires/nanorods of europium/terbium orthophosphate monohydrate with Eu^3＋ concentration of 6, 11, and 20 at.% were prepared by microwave synthesis method. The effects of Eu^3＋ doping concentration on structure, morphology and optical properties of nanomaterials were also investigated. The results showed that, for all studied Eu^3＋ doping concentrations, a single-crystalline phase of rhabdophane-type （Eu,Tb）PO4·H2O nanowires/nanorods was obtained by using microwave heating of an aqueous solution of terbium（Ⅲ） nitrate, europium（Ⅲ） nitrate and NH4H2PO4 with pH=2. The length and width of these nanowires/nanorods ranged from 150 to 300 nm and from 10 to 50 nm, respectively. The evidence of energy transfer from Tb^3＋ to Eu^3＋ due to the energy overlap between the donor Tb^3＋ and the acceptor Eu^3＋was observed obviously via a significant enhancement in the luminescent intensity of Eu^3＋. Keywords：

PMD and CD Characterization of Chirped FBG Using Microwave Photonic Technique

We present and demonstrate experimentally a new method for measuring the polarization-mode-dispersion(PMD) of a Chirped Fiber Bragg Grating. The technique has also been applied to accurate chromatic dispersion evaluation by removing the influence of PMD.

超声引导微波消融治疗腹壁子宫内膜异位症

目的探讨超声引导下微波消融(MWA)治疗腹壁子宫内膜异位症(AWE)的安全性和有效性。资料与方法回顾性收集2014年8月—2023年6月在北京友谊医院接受MWA治疗AWE的患者17例(共19个病灶)。治疗前后使用常规超声、彩色多普勒超声和静脉超声造影观察病灶变化情况。记录治疗后3、6、12个月AWE病灶体积、体积缩小率、疼痛缓解及并发症情况,评估治疗效果。结果超声造影显示所有病灶均一次完全消融成功。病灶平均初始体积为(7.46±5.82)ml,术后3、6、12个月随访时体积分别缩小至(4.32±2.76)ml、(2.47±1.68)ml、(1.72±1.16)ml(t=0.423,P=0.005;t=0.198,P=0.001;t=0.556,P=0.002),平均体积缩小率分别为(46.18±24.36)%、(61.43±18.72)%、(74.25±13.26)%。所有患者治疗12个月后腹壁周期性切口疼痛明显减轻或消失。1例患者术后出现局部皮肤灼伤,其余患者未出现严重并发症。结论MWA治疗AWE安全有效,值得进一步研究。

1 A/mm高电流密度金刚石微波功率器件

基于自对准栅电极制备技术,研制了具有低导通电阻和高电流密度的氢终端金刚石微波功率器件。采用高功函数金属Au与氢终端金刚石实现了良好的欧姆接触,接触电阻为0.73Ω·mm。得益于较低的源漏串联电阻和低损伤Al2O3栅介质原子层沉积工艺,金刚石微波器件的导通电阻低至4Ω·mm,饱和电流密度达1.01 A/mm,最大跨导为213 mS/mm,最大振荡频率达58 GHz。研究了该器件在2 GHz和10 GHz频率下连续波功率输出特性,发现在15 V低工作电压下即可分别实现1.56 W/mm和1.12 W/mm的输出功率密度,展现出自对准技术在研制高电流和高输出功率金刚石微波器件上的潜力。

一种旋转移相式高功率微波反射阵列天线

利用旋转移相技术的几何相位调控方法,提出一种基于传输相位差概念的波束扫描高功率微波反射阵列天线。电磁仿真结果表明,所设计的三叉戟形反射阵列天线单元工作于9.5~10.5 GHz,在0~40°入射角度下具有360°范围内的线性相位调控能力,真空条件下的功率容量达到1.11 GW。采用该单元设计了半径为200 mm的圆形口径反射阵列天线,并使用全波仿真软件进行验证,利用口径相位分布的可重构特性,所设计的反射阵列天线可以实现±40°范围内的波束扫描。在10 GHz时,波束扫描过程中的增益下降小于1.7 dB,最大增益达到31.1 dBi,对应口径效率为73.42%,最低口径效率超过50%,副瓣电平和轴比始终低于-18.7 dB和1.6 dB。

响应面优化微波辅助提取壶瓶碎米荠硒化合物

以壶瓶碎米荠粉末为原料,以硒含量为指标,采用响应面法对微波辅助提取壶瓶碎米荠硒化合物进行工艺优化。结果表明:壶瓶碎米荠提取液的最佳提取工艺条件为微波提取30 min后水浴浸提3 h、料液比1∶25(g∶mL)、提取温度50℃、乙醇浓度60%,此条件下壶瓶碎米荠提取物中硒含量为745.159μg·g^(-1),提取率为95.6%。