저강도 초음파 및 레이저를 이용한 장관골 불유합의 치료

전인호,오창욱,김성중,경희수,박일형,박병철,인주철,여준영 대한골절학회 2003 대한골절학회지 Vol.16 No.2

목 적: 저강도 초음파는 인체 및 동물 실험에서 골조직에 낮은 미세한 물리적 압력을 가하여 골절의 치유에 유리한 영향을 주고, 레이저 (LASER)는 심부 조직에 혈류를 증가시키고, 세포 내 잠재된 에너지를 증가시키는 것으로 알려져 있다. 이에 저자들은 임상적으로 확진된 장관골 붕류합의 치료에 있어 펄스형 저강도 초음파와 레이저를 적용하고 그 효용성을 알아보고자 하였다. 대상 및 방법: 초음파/레이저의 치료 효과를 비교하기 위하여 장관골 불유합으로 확진된 16예 중 8예는 연구군으로 골이식술 후 저강도 초음파와 레이저 치료를 추가하였고 대조군 8예에 대해선 일반적인 골이식술만 시행하여 조사하였다. 남자가 11예, 여자가 5예, 평균 연령은 41.7세 (19~62세)였고, 불유합 부위는 대퇴골이 10예, 경골이 6예였다. 첫 수상으로 인한 골절 후 초음파/레이저 치료까지 시간(골절 연력)은 평균 502일이었다. 결 과: 8예의 연구군에서는 완전 골유합이 6예에서 이루어졌으며 유합까지의 시간은 평균 141일 (101~202일)로 나타난 반면, 8례ㅢ 대조군에서는 5예에서 골유합이 이루어졌고, 유합까지의 시간은 평균 240일 (183~283일)이었다. 결 론: 저강도 초음파/레이져 골절 치료기가 반복된 수술로 인한 난치성 장관골 불유합의 치료에 있어 골이식술과 함께 사용될 경우 긍정적인 효과가 있었고, 특히 최초 가골 형성에 있어 대조군에 비해 그 시간을 줄일 수 있었따. Purpose: Low-intensity, pulsed ultrasound (LIPUS) has demonstrated a stimulation and acceleration of the normal fracture-repair process in cellular bases as well in animal and human models. In this study, the adjunctive effect of LIPUS and LASER was investigated in established nonunion of the long bones. Materials and Methods: Study group consisted of eight patients to whom conventional bone graft and adjunctive LIPUS and LASER was applied. On the other hands, eight patients in the control group underwent bone graft only. Eleven men and five women were included in this study and the average age of the patients was 41.7 years (range, 19~62 years). Six of the tibias and ten of the femurs met the criteria for established nonunion. The average fracture age, the post-fracture period before the start of LIPUS/LASER treatment, was 502 days. Results: Seven of the ten nonunions who were treated by LIPUS and LASER healed completely in an average treatment time of 141 days (range, 101~202 days) and otherwise, in control group, five of the eight nonunions healed completely, in 240 days (range 183~283 days). Conclusion: This clinical study showed a positive effect of LIPUS and LASER on the rate of osseous repair, especially accelerated time to initial callus cortical bridging compared to that of conventional treatment.

廢CRT의 再活用 工程에서 발생한 슬러지로부터 Y의 회수

田埈美,李在天,鄭鎭己,金南澈 공주대학교 자원재활용 신소재 연구센터 2002 센터사업 성과집 Vol.- No.1

폐CRT의 재활용 공정에서 Panel 유리에 도포 된 형광체의 제거 시 발생하는 슬러지로부터 Y를 회수하는 연구를 수행하였다. HCl 및 NHO_3을 사용하여 Y를 침출하였으며 산 농도, 침출온도, 침출시간, 광액농도가 침출율에 미치는 영향을 조사하였다. 또한 침출액으로부터 Y와 Pb를 침전 법으로 회수하는 실험을 행하였다. 슬러지로부터 HCl 및 HNO_3에 의한 Y의 침출거동은 유사한 경향을 나타내었다. 광액농도를 280 g/L로 하여 90℃에서 3.0M HCl 및 HNO_3으로 침출 하였을 때 시간에 따라 Y의 침출율은 증가하다가 40분 이상에서는 각각 93%, 90%로 일정한 침출율을 나타내었다. 침출액에 H_2C_2O_4을 첨가하여 Y를 회수하였으며 Pb는 Na_2SO_4를 가하여 PbSO_4로 제거하였다. A study on the recovery of yttrium was conducted using the phosphor sludges generated in the recycling process of obsolete CRTs. Yttrium was leached by HCl and HNO_2. The leaching efficiency of yttrium was extensively investigated in terms of acid concentration, leaching temperature and time, and pulp density. Yttrium and lead was recovered from leaching solutions also by precipitation method. The leaching behavior of yttrium was similar in both acids. The leaching efficiency of yttrium for both acids increased with time at the conditions of 3.0M, 90℃, and 280 g/L of pulp density. After 40 minutes, it was saturated to 93% and 90% for HCl and HNO_3, respectively. Yttrium was recovered from leaching acid solution by the addition of H_2C_2O_4 while lead was removed as PbSO_4 by Na_2SO_4.

핸드 마우스를 기반으로 한 휴먼인터페이스 기술의 설계 및 구현

황철호;이형호;전영준;김진일 東義大學校産業技術開發硏究所 2012 産業技術硏究誌 Vol.26 No.-

컴퓨터 기술의 발전과 더불어 컴퓨터 인터페이스는 최근 HCI(Human Computer Interaction)와 같이 자연스럽고 친숙한 환경으로 변화되고 있다. 본 논문에서는 컴퓨터 비전을 기반으로 웹 카메라를 사용하는 손 영역 검출 과정 및 손동작 추적 방법을 제시하고 이에 의한 휴먼 인터페이스를 제안한다. 손 영역 검출 단계에서는 가우시안 필터를 이용하여 노이즈를 제거하고, YCbCr 컬러공간을 이용하여 피부색을 검출한다. 손동작 추적 단계에서는 손 영역의 무게중심 좌표를 찾는 방법을 선택하고, 칼만 필터를 이용하여 손동작 위치 정보를 예측하여 손동작 인식률을 높인다. 마우스 이벤트 처리 단계에서는 레이블링을 이용하여 손가락 개수를 검출하며, 이를 이용하여 마우스 이벤트를 수행하도록 한다. 이 방법으로 구현된 핸드 마우스를 응용프로 그램에 적용함으로써 보다 자연스럽고 친숙한 휴먼 인터페이스를 구현한다.

세로토닌성 항우울제가 백서의 Schedule-Induced Polydipsia에 미치는 영향

이기철,이정호,박중섭,최영민,전성일,정홍경,하준명,정재현 대한생물치료정신의학회 1999 생물치료정신의학 Vol.5 No.2

Object : Schedule-induced polydipsia is considered as an animal model of obsessive-compulsive disorder inrats. The authors evaluated the chronic effects of fluoxetine and clomipramine as serotonergic antidepressants and haloperidol as dopaminergic antagonist on the schedule-induced polydipsia in rat.Methods : Spraque-Dawley rats weighing 200-250gm were individually housed, maintained and allowed free access to water for 1 week. And then the rats were placed on a restricted diet. To induce polydipsia, rats were placed in automatic cage where a pellet dispenser automatically dispensed 90mg pellets on a fixed-time 60 seconds(FT 60s) feeding schedule over 150-minute test session for a day. Water was available at all times during the feeding schedule in automatic cage. After 4 weeks of daily exposure to the FT 60s feeding schedule, experimental rats met a predetermined criterion for polydipsic behavior(greater than 3 times of water per session on average). 4 groups of rats were administered fluoxetine(5mg/kg/i.p.), clomipramine(5mg/kg/i.p.), haloperidol(0.1mg/kg/i.p.), vehicle(1cc/kg/i.p.) for 3 weeks. Rats were tested once a week to access schedule induced polydipsic behavior. The chronic effects of experimental drugs on schedule induced polydipsic behavior were analyzed with repeated analysis of variance and Scheffe test as a post-hoc comparison.In order to measure water consumption in non-polydipsic food-deprived rats, a separate group of rats(N=8) were individually housed and given a single bolus(14.5 gm) of food per day which maintained them at their average body weight.Results and Conclusion : The results were as follows ;1) After 4 weeks of daily feeding procedure with fixed time schedule for 60 seconds per day, the experimental group showed significant differences than the control in the amount of water consumption as compared with their baseline water intakes. At the same periods, there were no differences between the experimental group and the control in body weight. 2) The clomipramine treated group and the fluoxetine treated group showed significant decrease in the amount of water intake as compared with their baseline of polydipsic water intakes for 3 weeks of treatment. However, the haloperidol treated group and the vehicle control group showed no changes of amounts of water intake for 3 weeks of treatment as compared with their baseline of polydipsic water intakes. 3) At 2 weeks of drug treatment, clmipramine treated group(16.88±6.51ml) and the fluoxetine treated group(22.50±10.35ml) showed significantly lower amounts of water intake than the haloperidol treated group (41.25±7.06ml) or vehicle control group(37.50±12.54ml). And also the clomipramine treated group(13.75±5.18ml) and the fluoxetine treated group(18.75±3.54ml) showed significantly lower amounts of water intake than the haloperidol group(35.00±11.65ml) and the vehicle control(34.38±6.78ml) at 3 weeks of drug treatment. Above findings suggest that the fixed time feeding procedure for schedule-induced polydipsia as an animal model of obsessive compulsive disorder was effective to the evaluation of pharmacological challenge study. The author confirmed that schedule-induced polydipsia was successfully decreased for 3 weeks of administration of clomipramine and fluoxetine but there was no response to haloperidol.

Clozapine이 백서의 Schedule-Induced Polydipsia에 미치는 영향

이기철,정홍경,이정호,홍승범,최영민,전성일,정재현,하준명 대한생물치료정신의학회 2000 생물치료정신의학 Vol.6 No.2

Object : This study was designed to evaluate the effects of clozapine which is one of most useful atypical antipsychotics in the schedule-induced polydipsic rat which is an animal model of obsessive-compulsive disorder. Methods : Spraque-Dawley rats were placed in automatic cage where a pellet dispenser automatically dispensed 90mg pellets on a fixed-time 60 seconds(FT- 60s) feeding schedule over 150-minute test session for 4 weeks. After 4 weeks of daily exposure to the FT-60s feeding schedule, experimental rats met a predetermined criterion for polydipsic behavior(greater than 3 times of water per session on average). Rats were stratified into clozapine(0.34mg/kg,i.p.), clozapine(14.63mg/kg,i.p.), clomlpramine(5mg/kg,i .p.), and vehicle (1cc/kg,i.p.) group and treated with each drugs for 3 weeks. To identify the non-polydipsic food-deprived rats, a separate group of rats(N=8) were individually housed and given a single bolus(14.5gm) of food per day which maintained them at their average body weight. Results : The results were as follows ; 1)After 4 weeks of scheduled feeding procedure, the experimental group showed significant differences than bolus control in the amount of water consumption as compared with their baseline of water intakes for 4 weeks. At the same periods, there were no differences between the experimental group and bolus control in the borty weight. 2)The clomipramine group, the clozapine 0.34mg group and the clozapine 14.63mg group showed significant decrease in the amount of water intake for at 2nd & 3rd week of drug treatment as compared with their baseline of polydipsic water intakes. But, the vehicle control group showed no changes of amounts of water intake for 3 weeks of treatment as compared with their baseline of polydipsic water intakes. Conclusion : Above findings suggest that the fixed time feeding Procedure for Schedule induced polydipsia as an animal model of obsessive compulsive disorder was effective to the evaluation of pharmacological challenge study. In clinical situation, the authors suggest that atypical antipsychotic drugs which act as serotonin and dopamine receptor antagonist may be helpful to improve the symptoms of the patients with treatment refractory obsessive-compulsive disorder.

Risperidone이 백서의 Schedule-Induced Polydipsia에 미치는 영향

이기철,이정호,윤도준,최영민,전성일,김태수,정홍경,하준명,정재현 大韓神經精神醫學會 2000 신경정신의학 Vol.39 No.3

연구목적 : 강박장애의 원인론중 세로토닌-도파민 가설에 기초하여 강박장애 동물모형으로 고려되는 고정된 시간 간격으로 평소의 먹이섭취량보다 작은 양의 음식물을 백서에게 장기간 공급하여 다음중(schedule-induced polydipsia : SIP)을 유발시켰다. SIP모형에 강박장애에 효과적이라고 알려진 선택적 세로토닌 재흡수 차단제로서 fluoxetine을 장기 투여하고, 신경절후 5-HT²와 도파민 D² 수용체를 동시에 차단하는 risperidone을 투여하고, 신경절후 도파민 수용체 차단제인 haloperidol을 투여하였다. 그결과로서 risperidone이 강박장애 동물모형으로 고려되는 SIP에서 어떤 영향을 미치는지 알아보았다. 방 법 : SIP를 유발하기 위해 각각의 사육상자에 1정당 90㎎의 사료를 자동급이장치 (automatic dispenser)에서 60초당 1정씩 고정된 시간 간격으로 하루에 150분씩 공급하였다. 4주간 고정된 시간 간격으로 머기를 공급하고 매주 음수량과 체중을 측정한 실험 동물과 동등한 사료의 양을 한번에 덩어리로 공급받은 통제 집단의 체중과 음수량을 비교하였다. SIP 행동변화를 보인 실험 동물들을 fluoxetine 5㎎/㎏(N=8), risperidone 0.1㎎/㎏(N=8), haloperidol 0.1㎎/㎏(N=8), 그리고 vehicle 대조군 1㏄/㎏(N=8)으로 나누고 각각의 실험 동물군에서 3주간에 걸쳐서 실험 약물을 매일 복강내 주사하였다. 매주 실험 동물의 음수량과 체중을 측정, 비교하였다. 결 과 : 1) 고정된 시간 간격으로 제한된 먹이를 공급한 실험 동물군은 1주부터 4주에 걸쳐서 기저치보다 유의한 음수량의 증가를 보였다. 반면 통제 집단은 2주째 음수량이 일시적으로 증가한 소견 이외에 4주간의 실험 기간중 유의한 변화는 보이지 않았다. 실험 동물과 통제 집단간의 음수량에서 3주와 4주째에 실험 동물이 통제 집단보다 유의하게 높은 음수량을 보였지만 양군간에 체중의 차이는 보이지 않았다. 2) 각각의 실험 동물군 내에서 risperidone 0.1㎎ 투여군은 약물 투여 2주부터 3주까지 기저치 음수량과 비교하여 유의한 저하를 보였다. Risperidone 0.5㎎ 투여군은 약물터여 3주에서 기저치의 음수량과 비교하여 유의한 저하를 보였다. Fluoxetine 투여군은 약물 투여 시작 1주부터 3주에서 기저치의 음수량과 비교하여 유의한 저하를 보였다. 한편, haloperidol 투여군과, vehicle은 3주간에 걸친 약물 투여에서 각각의 기저치 음수량과 비교하여 차이를 보이지 않았다. 3) 실험 동물 각 군간에 약물 투여 시간 경과에 따른 음수량을 비교한 바, 약물투여 1주에서 각 군간에 유의한 차이는 없었다. 약물 토여 2주에서 fluoxetine 투여군, risperidone 0.1㎎ 투여군, 그리고 risperidone 0.5㎎투여군이 haloperidol 투여군과 비교하여 유의한 차이를 보였다. 약물투여 3주째에 fluoxetine투여군, risperidone 0.1㎎ 투여군, 그리고 risperidone 0.5㎎투여군이 haloperidol 투여군, vehicle과 비교하여 유의한 음수량의 저하를 보였다. 결 론 : 백서의 강박 행동은 fluoxetine, risperidone에 의해 효과적으로 억제되었으나 haloperidol에는 반응이 없었으므로, 임상에서 난치성 강박장애의 치료에 비정형 항정신병 약물 투여를 고려해 볼 수 있다고 제안한다. Objectives : This study was designed to evaluate the effects of risperidone on the schedule-induced polydipsia(SIP) which is one of animal model of obsessive-compulsive disorder in rats. We administered risperidone as a serotonin and dopamine blocking agent, fluoxetine as a selective serotonin reuptake inhibitor, and haloperidol as a dopamine antagonist to rats which showed schedule-induced polydipsic behaviour. Methods : Sprage-Dawley rats weighing 200∼250gm were individually housed and maintained and allowed free access to water. The rats were placed on a restricted diet. To induce polydipsia, rats were placed in the cage where a pellet dispenser automatically dispensed 90㎎ pellets on a fixed-time 60 seconds(FT 60s) feeding schedule over 150 minute test session per day. Water was available at all times in the cage. After 4 weeks of daily exposure to the FT 60s feeding schedule, experimental rats met a predetermined criterion for polydipsic behavior(greater than 3 times of water per session on average). 5 groups of rats were administered risperidone(0.1㎎/㎏, i.p), risperidone(0.5㎎/㎏, i.p), fluoxetine(5㎎/㎏, i.p), haloperidol(0.1㎎/㎏, i.p), and vehicle(1㏄/㎏, i.p) for 3 weeks. The rats were tested once a week to access schedule induced polydipsic behavior. Water bottles were weighed before and after the 150-minute test session. The chronic effects of administration of experimental drugs on schedule induced polydipsic behavior were analyzed with ANOVA and Scheffe test as a post-hoc comparison. In order to measure water consumption in non-polydipsic food-deprived rats, a separate group of rats(N=8) was individually housed and given a single bolus(14.5gm) of food per day which maintained them at their average body weight. Results : The results were as follows ; 1) After 4 weeks of scheduled feeding procedure, the experimental group showed significant differences than the bolus control in the amount of water consumption as compared with their average water intakes for 4 weeks. At the same periods, there were no differences between the experimental group and the bolus control in the body weight. 2) The fluoxetine group showed significant decrease in the amount of water intake at 1st, 2nd, and 3rd weeks of drug treatment as compared with their average amount of polydipsic water intakes. The risperidone 0.1㎎ group and the risperidone 0.5㎎ group showed significant decrease in the amount of water intake at the 3rd weeks of drug treatment as compared with their baseline of polydipsic water intakes. However, the haloperidol group and the vehicle control group showed no changes of amounts of water intake for 3 weeks of treatment as compared with their baseline of polydipsic water intakes. 3) The fluoxetine group(22.5±10.4ml) showed significantly lower amounts of water intake than haloperidol group(41.3±7.1ml) at 2nd weeks of drug treatment. And also the fluoxetine group(18.8±3.5ml) showed significantly lower amounts of water intake than the haloperidol group(35.0±11.7ml) and the vehicle control(34.4±6.8ml) at 3rd weeks of drug treatment. The risperidone 0.1㎎ group and the risperidone 0.5㎎ group showed significantly lower amounts of water intake than the haloperidol group(35±11.7ml) at 2nd weeks and the vehicle control(37.5±12.5, 34.4±6.8ml) at 2nd and 3rd weeks of drug treatment. Conclusions : Above findings suggest that the fixed time feeding procedure for schedule induced polydipsia could be applied as an effective animal model of obsessive compulsive disorder for the evaluation of pharmacological challenge study. We confirmed that chronic treatment with risperidone revealed antipolydipsic effect as effective as fluoxetine on the schedule-induced polydipsic behaviour but the onset of effect was later than fluoxetine.

[11C]-(R)-PK11195 positron emission tomography in patients with complex regional pain syndrome: A pilot study

Jeon, So Yeon,Seo, Seongho,Lee, Jae Sung,Choi, Soo-Hee,Lee, Do-Hyeong,Jung, Ye-Ha,Song, Man-Kyu,Lee, Kyung-Jun,Kim, Yong Chul,Kwon, Hyun Woo,Im, Hyung-Jun,Lee, Dong Soo,Cheon, Gi Jeong,Kang, Do-Hyung Williams & Wilkins Co 2017 Medicine Vol.96 No.1

ABSTRACT: Complex regional pain syndrome (CRPS) is characterized by severe and chronic pain, but the pathophysiology of this disease are not clearly understood. The primary aim of our case–control study was to explore neuroinflammation in patients with CRPS using positron emission tomography (PET), with an 18-kDa translocator protein specific radioligand [C]-(R)-PK11195. [C]-(R)-PK11195 PET scans were acquired for 11 patients with CRPS (30–55 years) and 12 control subjects (30–52 years). Parametric image of distribution volume ratio (DVR) for each participant was generated by applying a relative equilibrium-based graphical analysis. The DVR of [C]-(R)-PK11195 in the caudate nucleus (t(21) = −3.209, P = 0.004), putamen (t(21) = −2.492, P = 0.022), nucleus accumbens (t(21) = −2.218, P = 0.040), and thalamus (t(21) = −2.395, P = 0.026) were significantly higher in CRPS patients than in healthy controls. Those of globus pallidus (t(21) = −2.045, P = 0.054) tended to be higher in CRPS patients than in healthy controls. In patients with CRPS, there was a positive correlation between the DVR of [C]-(R)-PK11195 in the caudate nucleus and the pain score, the visual analog scale (r = 0.661, P = 0.026, R = 0.408) and affective subscales of McGill Pain Questionnaire (r = 0.604, P = 0.049, R = 0.364). We demonstrated that neuroinflammation of CRPS patients in basal ganglia. Our results suggest that microglial pathology can be an important pathophysiology of CRPS. Association between the level of caudate nucleus and pain severity indicated that neuroinflammation in this region might play a key role. These results may be essential for developing effective medical treatments.

Long-term outcomes after noncurative endoscopic resection of early gastric cancer: the optimal time for additional endoscopic treatment

Jeon, Mi Young,Park, Jun Chul,Hahn, Kyu Yeon,Shin, Sung Kwan,Lee, Sang Kil,Lee, Yong Chan Elsevier 2018 Gastrointestinal Endoscopy Vol.87 No.4

<P><B>Background and Aims</B></P> <P>We aimed to evaluate long-term outcomes with noncurative endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) and surveillance strategies such as the optimal time for additional endoscopic treatment in patients with noncurative ESD.</P> <P><B>Methods</B></P> <P>Of 2527 patients who underwent gastric ESD for EGC, 512 (20.3%) patients with noncurative resection were reviewed. Noncurative resection is defined as positive resected margins on histology, lymphovascular infiltration, or beyond the expanded criteria for ESD.</P> <P><B>Results</B></P> <P>The mean ± standard deviation follow-up duration was 79.0 ± 55.7 months. A total of 264 patients (51.6%) and 50 patients (9.8%) underwent surgery and endoscopic treatment after noncurative resection, respectively, whereas 198 patients (38.7%) were observed. Cancer-specific survival and disease-free survival rates were significantly different among the surgery, other endoscopic treatment, and observation groups (96.7%, 86.8%, and 86.2%, respectively; <I>P</I> =.030; and 92.5%, 73.6%, and 63.0%, respectively; <I>P</I> < .001). When patients who underwent surgery were excluded, the disease-free survival rate of recurrence was not significantly different between the endoscopic treatment and observation groups (73.6% vs 63.0%; <I>P</I> = .548). To exclude the potential for the presence of lymph node metastasis, we further analyzed disease-free survival of local recurrence by comparing the patients with only a positive lateral resection margin. The disease-free survival rate was higher in the endoscopic treatment group than in the observation group (89.2% vs 69.1%; <I>P</I> = .023). Moreover, additional endoscopic treatment within 3 months showed significant associations with lower risk of local recurrence on multivariate analysis (hazard ratio, 0.017; 95% confidence interval, 0.002-0.260; <I>P</I> = .003).</P> <P><B>Conclusions</B></P> <P>In patients with noncurative ESD, additional surgery showed a better long-term outcome; moreover, when a positive lateral resection margin was the only noncurative factor, additional endoscopic treatment within 3 months could be considered to improve disease-free survival.</P>

Very large suspended graphene as an efficient electron-transparent gate electrode

Jeon, Hyojin,Choi, Young Chul,Park, Sora,Kang, Jun-Tae,Go, Eunsol,Lee, Jeong-Woong,Kim, Jae-Woo,Jeong, Jin-Woo,Song, Yoon-Ho Elsevier 2017 Carbon Vol.119 No.-

<P>Although a focused electron beam is required in field emission-based various applications, the electron beam is generally diverged in a conventional triode because the gate has a circular aperture through which the electrons are accelerated to reach the anode. To prevent the beam divergence, a suspended multi-layer graphene (MLG) was fabricated on a very large gate aperture to be used as an electron-transparent gate in a field emission triode. The suspended MLG was observed to have several micro-openings with an average diameter of similar to 5 mu m formed during a transfer. It was observed that the MLG with micro-openings was likely to act as an efficient transparent gate for electrons even with large number of graphene layers, exhibiting a high transmittance of similar to 90%. The solid angles of the beams obtained using conventional gate aperture and suspended MLG gate were 0.225 and 0.074 sr, respectively, indicating that the suspended MLG resulted in a focused electron beam. Simulations confirm that the suspended MLG with micro-openings suppresses the beam divergence in a given triode configuration because the MLG results in the flattened electric field profiles between gate and cathode whereas a distorted potential distribution causing beam divergence occurs around the aperture in a conventional triode. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Blue phosphorescent organic light-emitting devices based on carbazole/thioxanthene-S,S-dioxide with a high glass transition temperature

Jeon, Young Pyo,Kim, Kyu Sung,Lee, Kyeong Kyun,Moon, In Kyu,Choo, Dong Chul,Lee, Jun Yeob,Kim, Tae Whan The Royal Society of Chemistry 2015 Journal of materials chemistry. C, Materials for o Vol.3 No.24

<▼1><P>A bipolar host material for blue organic light-emitting devices was synthesized by incorporating electron-donating carbazole and electron-accepting thioxanthene-<I>S</I>,<I>S</I>-dioxide into one molecule using a solventless green reaction.</P></▼1><▼2><P>Carbazole/thioxanthene-<I>S</I>,<I>S</I>-dioxide (EBCz-ThX) bipolar molecules were synthesized by incorporating electron-donating carbazole and electron-accepting thioxanthene-<I>S</I>,<I>S</I>-dioxide into one molecule at 85 °C using a solventless green reaction method. The EBCz-ThX bipolar molecule exhibited a high glass transition temperature of 227 °C and a high triplet energy of 2.94 eV. The highest occupied molecular orbital (HOMO, −5.95 eV) and lowest unoccupied molecular orbital (LUMO, −2.63 eV) energy levels of the molecule matched the HOMO energy level of the hole transporting layer and the LUMO energy level of the electron transporting layer, respectively, which facilitated the injection of holes and electrons. Phosphorescent organic light-emitting devices (PHOLEDs) were fabricated with EBCz-ThX as a blue host material and with bis((4,6-difluorophenyl)-pyridinate-N,C2′)picolinate as a blue dopant, and the doping ratio was controlled to optimize the performance of the blue PHOLEDs. Blue PHOLEDs with a 15% doping ratio at 100 cd m<SUP>−2</SUP> showed excellent performances and low operation voltages with quantum and current efficiencies of about 12% and 24 cd A<SUP>−1</SUP>, indicating that the EBCz-ThX acted as an excellent host for the blue PHOLEDs. The external quantum efficiency at 1000 cd m<SUP>−2</SUP> was improved up to 30% in comparison with that of a conventional PHOLED with an mCP of 8% doping ratio.</P></▼2>