Search

Direct Z-scheme designs perform well in light-to-fuel conversion. Here, an active and stable ternary Z-scheme core-shell heterojunction for photocatalytic hydrogen evolution (PHE) is fabricated consisting of hexagonal 2D α-Fe2O3 (as photocatalyst II) and 2D nitrogen-doped graphene (NGr as photocatalyst I) functionalized with the Pt single-atoms (SAs) cocatalyst. Under visible light, the 2D/2D α-Fe2O3 @NGr3[sbnd]PtSAs (NGr shell thickness of 3 nm and Pt loading of 0.5 wt%) achieves a remarkable PHE of 6.4 µmol mgcat−1 h–1, which is 16.4- and 3.28-times higher than those of free NGr (0.39 µmol mgcat−1 h–1) and binary α-Fe2O3 @NGr3 (1.95 µmol mgcat−1 h–1), thus outperforming the currently-advanced PHE catalysts. The outstanding performance is due to the superiority of a direct 2D/2D Z-scheme core-shell fabrication, including a large surface area for light harvesting, facile charge separation and transfer, and the workability of Pt SAs sites. Theoretical investigations provide additional insight into the mechanistic process of the ternary system for PHE reactions.

Heteroatom doping into metal oxides advantageously modulates optoelectronic properties and provides promising possibilities for efficient light-to-energy conversion. Herein, nitrogen-doped ceria (N-CeO2) nanoparticles are prepared and then coupled with nitrogen-doped graphene (N-Gr) to create an active and long-lasting N-CeO2/N-Gr heterocatalyst. Optoelectronic features of N-doping materials (e.g., plasmon) are significantly improved toward the visible-light region, particularly for 3.9% N-CeO2/N-Gr nanocomposites. Namely, the 3.9% N-CeO2 possesses numerous catalytic active defects (N states, oxygen vacancy, and Ce3+ species), leading to a narrow bandgap energy and to the improved plasmonic properties of the ceria host, while the N-Gr preferably serves as an electron scavenger to collect plasmon-generated hot electrons migrating from 3.9% N-CeO2 to drive photocatalytic reactions under the irradiation of visible-light. Resultantly, the 3.9% N-CeO2/N-Gr photocatalyst delivers an impressive hydrogen evolution reaction (HER) rate of 3.7 μmol mgcat−1 h−1 under visible-light, which is 2.0- and 8.2-fold greater than those obtained from 3.9% N-CeO2 and CeO2 ones, respectively. Additionally, the combination of 3.9% N-CeO2 and N-Gr synergistically produces a long-lasting plasmonic HER photocatalyst system. Metal-free plasmonic N-doped oxides supported by N-doped graphene pave a promising pathway for efficient light-to-hydrogen fuel production accordingly.

Recently, various attempts have been made for light-to-fuels conversion, often with limited performance. Herein we report active and lasting three-factored hierarchical photocatalysts consisting of plasmon Au, ceria semiconductor, and graphene conductor for hydrogen production. The Au@CeO

We demonstrated lasing from TM modes in photonic nanobeam cavities. By varying the radius of air holes, Q-factor reaches around 1,000,000. The single-mode lasing action was performed at room temperature, and confirmed by numerical results.

Supported plasmonic Au nanoclusters (NCs) consisting of a few tens of atoms can potentially offer great advantages for the light-driven hydrogen evolution reaction (HER). Here, we report on the synthesis of well-dispersed and stable plasmonic Au NCs of 0.5-1.0 nm size on nitrogen-doped high surface area graphene (N-Gr) via freeze-drying and pyrolyzing in argon. The Au NCs/N-Gr photocatalyst exhibits under visible-light an impressive HER achievement (3.16 mu mol mg(cat)(-1) h(-1)) compared to Au single atoms/N-Gr (2.06 mu mol mg(cat)(-1) h(-1)) and Au nanoparticles (20 nm size)/N-Gr (0.92 mu mol mg(cat)(-1) h(-1)), with a maximum apparent quantum yield of 14.30%. These performances are synergistically attributed to two effects: (a) the strong surface plasmon resonance stimulated by light absorption and transferred near the surface of Au NCs, where the N-Gr conductive support can prolong the plasmon-produced hot electrons and direct the light-to-hydrogen conversion; (b) a high catalytic efficiency of Au NCs/N-Gr nanocomposites.

Correction for ‘Plasmonic Au nanoclusters dispersed in nitrogen-doped graphene as a robust photocatalyst for light-to-hydrogen conversion’ by Dung Van Dao et al., J. Mater. Chem. A, 2021, DOI: 10.1039/D1TA05445G.

Background Although lower urinary tract symptoms (LUTS) show a higher prevalence with age, few studies have reported the trend of these examination tools including uroflowmetry, urodynamic study and cystoscopy. Methods We evaluated the trend of performance of uroflowmetry, urodynamic study and cystoscopy by using National Health Insurance Data from 2010 to 2015. Primary outcome findings included cumulative number of patients per year, cumulative age-standardized patient rate per year and per age group, and correlation between the number of patients per year and the percentage of population per year in each age group. Results The overall trend for frequency of uroflowmetry and cystoscopy showed an increasing pattern (P < 0.001, respectively) while the trend for frequency of urodynamic study showed a decreasing pattern (P < 0.001). After age standardization, the overall trend showed similar results. Correlation between the number of patients per year and the percentage of population per year showed a positive correlation in the 50s age group and the above 70s age group (P = 0.003 and < 0.01, respectively) on uroflowmetry and in the above 70s age group (P < 0.01) on cystoscopy. Urodynamic study showed negative correlations in the 50s age group and the above 60s age group (P = 0.001 and 0.01, respectively). Conclusion National trend for frequency of uroflowmetry, urodynamic study and cystoscopy showed a different trend. The increasing trend of uroflowmetry and cystoscopy was related with growth of the aged population. However, urodynamic study showed a decreasing trend regardless of the age group., Graphical Abstract

In this study, Anchor Pile Precast Retaining Wall (APC) with screw shape flange was investigated and the results were arranged for designing APC specifications. Since precast materials require special care when they are manufactured, carried or treated, more accurate design and analysis of optimized dimension are needed : thus moment distribution of front foot was checked. Through full-scale field test, form and optimal stiffening shape were obtained and through fracture test with real load, applicable load was reasonably calculated. Research result in this thesis could be used as guideline or standard of designing and constructing Anchor Pile Precast Retaining Wall with screw shape flange.

A deep-sea pressure vessel needs to protect the internal electrical equipment from the high external pressure. Thus, the pressure vessel should be designed to be watertight and structurally safe. In this study, a cylindrical-type pressure vessel comprising a hollow cylinder and cover plates at both ends is investigated. For communication between the internal electronic equipment and the external device, holes are bored on the cover plate to install underwater connectors. Considering the type of internal equipment and underwater connector specifications, multiple holes may be required. These holes can affect the structural safety of the pressure vessel cover plate. In this study, the optimum design of the hole arrangement in consideration of the structural safety of the cover plate was performed.

Over the past years, many research works have been carried out to investigate the factors which govern the performance of diesel engine. The air pollutant emission from the diesel engine is still a significant environmental con cern in many countries. In the present study, new system of smoke reduction of diesel engi ne is proposed. This new system is using vacuum equipment for capture smoke. To confirm new system experiments were performed at engine dynamometer. As a result of this experiment, the smoke reduction of this system was identified. Key words: Smoke, Diesel Engine, Vaccum Generating †교신저자(국민대학교 자동차공학전문대학원, E-mail:siu-ki@hanmail.net, Tel: 02-943-7630)1 국민대학교 자동차공학전문대학원 1. 서 론 전 세계적으로 지구온난화에 따른 환경문제에 대응하기 위해 국제협약을 통한 이산화탄소 규제가 본격화되고 있는 시점에서 동일 배기량 기준 가솔린엔진보다 20-30% 정도 이산화탄소 배출량이 적은 디젤엔진은 차세대 친환경적인 운송역할의 가장 현실적인 대안으로 부각되고 있다[1,2]. 그러나 디젤엔진은 과잉공기 조건에서 연소가 진행되기 때문에 배기가스 중에 산소가 다량 존재하여 가솔린 엔진에 적용되는 3원 촉매를 사용할 수 없다. 또한 확산 연소 형태의 연소특성 때문에 질소산화물(NOx) 생성뿐만 아니라 부분적 과농 지역에서는 매연이 다량 생성되는 문제를 근본적으로 안고 있다[3-4]. 이러한 문제를 해결하기 위하여 고압분사 등과 같은 분사 전략의 향상과 유동에 의한 혼합의 조절 등으로 많은 배출가스의 저감이 이루어졌지만 현재 강화되는 배출가스 규제를 만족시키기 위해서는 후처리장치의 개발은 필수적이다. 그리고 최근 들어 미세입자의 유해성이 대두되면서 입자상물질(대부분 매연입자)에 대한 관심이 늘어나고 있다. 현재 입자상 물질의 저감기술로는 매연여과장치(DPF ; Diesel Particulate Filter) 가 가장 효과적이며, 정부에서는 일부지역에서의 차량에 장착을 의무화

The design theory and experimental results of a true random noise radar system are presented in this paper. Target range information can be extracted precisely by correlation processing between the delayed reference and the signal received from a target, and the velocity information by the Doppler processing with successive correlation data. A K-band noise radar system was designed using random FM noise signal, and the characteristics of the fabricated system were examined with laboratory and outdoor experiments. A C-band random FM noise signal was generated by applying a low-frequency white Gaussian noise source to VCO(Voltage Controlled Oscillator), and a K-band Tx noise signal with 100 ㎒ bandwidth was obtained by using a following frequency multiplier. Two modified waveguide horn arrays were designed and fabricated, and used for the Tx and Rx antennas. The required amount of Tx/Rx isolation was attained by using a coupling cancellation circuit as well as keeping them apart with predetermined spacing. A double down-conversion scheme was used in the Rx and reference channels, respectively, for easy post processing such as correlation and Doppler processing. The implemented noise radar performance was examined with a moving bicycle and a very high-speed target with a velocity of 150 ㎧. The results extracted by the Matlab simulation using the logging data were found to be in a reasonable agreement with the expected results.

A process for covalent attachment of amines to other amines is described for nanodevice preparation. This method utilizes a linker with aldehyde and N-hydroxysuccinimide ester terminals separated by a heptyl spacer. Nanodevices consisting of amine or hydrazide-containing molecules (Lucifer Yellow, fluorescein-5-thiosemicarbazide, and 2-hydrazinopyridine) attached to the surface of a generation 4 amine-terminated poly(amidoamine) dendrimer were prepared as model compounds. In spite of the numerous amine groups present on the dendrimer, aggregate formation was negligible, yielding well-defined nanoconstructs. This negligible aggregation was attributed to the reversible imine bonds formed between the surface amine groups of the dendrimer and the aldehyde group of the linker. We also prepared a dual fluorophore-dendritic nanodevice in which fluorescein was attached to the dendrimer surface via the linker while rhodamine was directly bound to the dendrimer surface. Fluorescence, UV-visible spectrophotometry, size exclusion chromatography, electrophoresis, and dynamic light scattering were used to analyze these nanodevices.

The design technology to be developed in this study is technology related to the metal panel corner processing method of very high value-added, interior and exterior cladding material, in the architecture. This study is aimed at designing a Bending Die System that enables metal panel corner processing for the first time in Korea, by improving corrosion resistance (durability), weather resistance and elegances (design) for the connecting part of right angle cornering, where most serious problems occur in using metal steel plates of 2.5mm or thicker. This is used as a kind of metal ball and as architectural interior and exterior cladding material.

The design technology to be developed in this study is technology related to the metal panel comer processing method of very high value-added, interior and exterior cladding material, in the architecture. This study is aimed at designing a Bending Die System that enables metal panel comer processing for the first time in Korea, by improving corrosion resistance (durability), weather resistance and elegances (design) for the connecting part of right angle cornering, where most serious problems occur in using metal steel plates of 2.5mm or thicker. This is used as a kind of metal ball and as architectural interior and exterior cladding material.

OBJECTIVE The purpose of this study was to investigate the ultrasonographic and pathologic findings of nonpalpable thyroid carcinomas and reliable guidelines for fine-needle aspiration (FNA). METHODS Our study was approved by our Institutional Review Board, and written informed consent was waived. Between April 2004 and June 2006, screening ultrasonography was performed for 16,352 self-referred patients in the health care center. Among 1325 nonpalpable thyroid nodules in 1009 patients, pathologic results of FNA revealed 823 benign, 154 indeterminate, 198 nondiagnostic, and 150 malignant nodules. Fifty-eight malignant thyroid nodules (39 microcarcionomas and 19 carcinomas >1 cm, confirmed by both FNA and thyroidectomy) in 55 patients and 82 benign nodules (confirmed by both FNA and follow-up over 2 years) in 75 patients were included for the analysis. Three radiologists retrospectively analyzed the ultrasonographic features of these nonpalpable thyroid nodules for echogenicity, shape, margin, calcification, degree of cystic changes, and size. We compared the radiologic and pathologic findings between microcarcinomas and carcinomas larger than 1 cm for extra-capsular invasion, lymph node metastasis, bilaterality, and multicentricity using univariate analysis. RESULTS Marked hypoechogenicity, an irregular shape, a taller-than-wide shape, a well-defined spiculated margin, microcalcification, and an entirely solid nature were significant predictors for malignancy (P < .05), whereas a cutoff value of 1 cm in the longest diameter was not significant (P = .184). However, extracapsular invasion (P = .024) and lymph node metastasis (P = .019) were observed more frequently in carcinomas larger than 1 cm (73.7% and 42.1%, respectively) than in microcarcinomas (38.5% and 12.8%). CONCLUSIONS Ultrasonographic findings suggesting malignancy should be preferentially considered as indicators for FNA, regardless of size, in nonpalpable thyroid nodules. However, extracapsular invasion and lymph node metastasis are closely related to the size of the thyroid nodule.

In the current era of transplantation and therapeutic endoscopy, the role of the distal splenorenal shunt (DSRS) for portal hypertension (PH) has diminished. We reviewed the outcome of the use of DSRS in children to determine the usefulness of this operation. In the follow-up course for PH from 1987 to 2006, 15 patients who developed severe thrombocytopenia (platelet count

Background/Purpose The aim of the study was to review the gastrointestinal abnormalities occurring in association with situs anomalies. Methods Patients with situs anomalies were identified from the medical records of pediatric patients of Seoul National University Children's Hospital from January 1980 to July 2004. Retrospective study was undertaken. Diagnosis was made on the basis of the information obtained from a combination of echocardiography, angiography, abdominal ultrasonography, liver scan, upper gastrointestinal study, or abdominal computed tomography. Results A total 67 patients diagnosed as having situs anomalies were identified. There were 40 males and 26 females (1.54:1). Of these 67 patients, 45 patients (67%) were diagnosed as having situs inversus, 16 patients (24%) as having right isomerism, and 6 patients (9%) as having left isomerism. Of 45 patients with situs inversus, there were 26 patients (58%) who had intraabdominal abnormalities. These were duodenal atresia, biliary atresia, gastroschisis with malrotation, congenital hepatic fibrosis, tracheoesophageal fistula (type C), Currarino's triad, and pheochromocytoma. Of 16 patients with right isomerism, there were 14 patients (88%) who had intraabdominal abnormalities. These were hiatal hernia and diaphragmatic hernia. Of 6 patients with left isomerism, there were 4 patients (67%) who had intraabdominal abnormalities. These were malrotation and biliary atresia. Conclusion When a patient is noted to have congenital heart disease as part of situs anomalies, or if an atypical position of organs is noted at imaging evaluation, we recommend that the patient undergo chest radiography, abdominal ultrasonography, upper gastrointestinal study, and abdominal computed tomography.

Hepatocellular carcinoma (HCC) is a rare pediatric malignancy that is usually advanced at diagnosis, with a relatively poor prognosis. Extensive treatment, including complete tumor resection, is believed to be necessary for cure. This study was performed to analyze treatment results and to search for prognostic factors of pediatric HCC.Between March 1982 and February 2004 a total of 16 children had been diagnosed as having HCC in our institution, and a retrospective analysis was performed.The median age at diagnosis was 10.5 years, and the male/female ratio was 11:5. As a predisposing condition, hepatitis B virus (HBV) infections were present in 11 (68.8%) and liver cirrhosis in 8 (50.0%). Including 1 patient with a liver transplant, 4 patients (25.0%) underwent a primary operation with complete tumor resection, and 11 (68.8%) received neoadjuvant chemotherapy because of their inoperable state at diagnosis. After neoadjuvant chemotherapy, complete tumor resection was performed in four (36.4%). Thus complete resection was undertaken in a total of eight patients (50.0%). The estimated 5-year survival rate of all patients was 27.3%. The 5-year survival rate for patients who underwent complete tumor resection was 62.5%, and for those who underwent palliative resection or no operation it was 0%. The statistically significant prognostic factors were tumor stage, presence of metastasis, and complete tumor resection.This study confirmed that complete tumor resection is essential for cure in pediatric patients with HCC, and neoadjuvant chemotherapy improves the tumors' resectability.

1 The mitochondrial respiratory chain produces reactive oxygen species (ROS) during normal electron transport. Despite producing ROS, mitochondria are vulnerable to oxidative stress. Mitochondrial dysfunction has been associated with many degenerative diseases, making it important to identify compounds that protect mitochondria from ROS-mediated toxicity. Here we report that ciclopirox (CPX) blocks H2O2-induced mitochondrial injury by maintaining mitochondrial transmembrane potential (Deltapsim). 2 CPX completely blocked H2O2-stimulated release of lactate dehydrogenase (a marker of cell death) and decrease in MTT reduction (a marker of mitochondrial function) in adenocarcinoma SK-HEP-1 cells. 3 H2O2 rapidly depolarized the Deltapsim, and CPX blocked this H2O2-stimulated Deltapsim decrease. Similar data were obtained in experiments using mitochondria isolated from rat liver. 4 Furthermore, CPX effectively inhibited H2O2-induced mitochondrial permeability transition pore (MPTP) opening. In de-energized mitochondria, however, CPX did not inhibit Ca2+-evoked MPTP opening, indicating that CPX is not a direct inhibitor of the MPTP. 5 Oxygen consumption studies showed that in the presence of pyruvate and malate CPX restored the rate of state 3 to state 4 respiration decreased by H2O2. Consistent with this, CPX replenished ATP levels lowered by H2O2. 6 The present results indicate that CPX protects SK-HEP-1 cells from H2O2 cytotoxicity by inhibiting Deltapsim decrease and indirectly preventing MPTP opening.

Irradiation of cis, trans-l,2-dibenzoyl-3-methylcyclopropane (cis-1a) produced trans, trans-1,2-dibenzoyl-3-methylcyclopropane (trans-1a). This cis–trans isomerization was shown to be reversible through cleavage of the bond beta to both carbonyl (1,2-bond fission) while irradiation of cis, trans-l,2-dibenzoyl-3-phenylcyclopropane (cis-1b) gave trans, trans-1,2-dibenzoyl-3-phenylcyclopropane (trans-1b) irreversibly through cleavage of the bond beta to both carbonyl groups (1,2-bond fission) and the bond beta to phenyl group (1,3-bond fission). 1,2-bond fission of optically active trans-1b showed racemization only under irradiation. This racemization of trans-1b was considered to be responsible for irreversible cis–trans isomerization of cis, trans-1,2-dibenzoyl-3-phenylcyclopropane (cis-1b).

Solid and papillary epithelial neoplasm of the pancreas is an uncommon low-grade malignant tumor found predominantly in young females. In this paper, the authors report the tumor's clinical characteristics and the results of surgery in six children. Six cases of solid and papillary epithelial neoplasm of the pancreas pathologically verified at Seoul National University Children's Hospital between 1985 and 1997 were retrospectively analyzed. Four were girls and two were boys, and their mean age at surgery was 11.2 years (range 8-13 years). All patients presented with an abdominal mass and tumor ranging in size from 6.5 x 6.0 cm to 10.5 x 8.0 cm. Five were located in the head and one in the tail of the pancreas; exploration showed that no case involved local invasion or metastasis. All patients underwent complete resection, which involved five pancreaticoduodenectomies and one distal pancreatectomy. No patient died during surgery, and after a mean follow-up period of 5.5 years (range 1.5-12.5 years) all were alive with no recurrences. We believe that the malignancy of this tumor is low grade and that the prognosis is good. For a neoplasm arising anywhere in the pancreas, complete resection is the treatment of choice. Solid and papillary epithelial neoplasm of the pancreas of children shows less female preponderance in children than in adults.

Currarino et al, in 1981, described an association of a congenital anorectal stenosis, or another type of low anorectal malformation, an anterior sacral defect, and presacral mass. Eleven patients with this anomaly were treated at the Department of Pediatric Surgery, Seoul National University Children's Hospital from 1984 to 1995. Among these patients, low-type imperforate anus (IA) was seen in three cases and anorectal stenosis was present in eight cases. Presacral masses included seven teratomas, two meningoceles, one dermoid cyst, and one enteric cyst with dermoid cyst. All had a deformed sacrum. Among the eight with anorectal stenoses, posterior sagittal anorectoplasty (PSARP) with diverting colostomy was performed in seven cases, and repeated rectal dilatation was performed in one case. Among the three low-type IA, anoplasty was performed in two cases and PSARP was performed in one case. Although PSARP is a safe and satisfactory method facilitating the excision of the presacral mass, in meningoceles the repair should be performed before correction of anorectal malformation because of the risk of meningitis that can occur when surgeries are done simultaneously. In two cases, untethering of a tethered spinal cord was performed. All patients are continent. Because the incidence of Currarino triad is high when there is an anorectal stenosis (38% in the present series), the Currarino triad should be suspected in anorectal stenosis. Magnetic resonance imaging is a preferred diagnostic method because the incidence of association of tethered cord in this triad is high (18% in the present series).

The triplex intramolecular Diels-Alder reaction of cyclopentadienes and styrene-like dienophiles that are linked with an alkyl chain was investigated. Sensitized irradiation of alkenylcyclopentadiene with 9,10-dicyanoanthracene leads to a [4 + 2] adduct without [1,5]-hydrogen shift when the linking chain contains three carbon atoms. If the linking chain contains only two carbon atoms, [1,5]-hydrogen shift occurs prior to cyclization, leading to the formation of a less strained [4 + 2] adduct.

Three isomers of damascenone, odorous terpenic ketones, have been synthesized conveniently from a same starting material, ethyl 2,6,6-trimethyl-4-oxo-2-cyclohexene-1-carboxylate(1), which was easily available by the acid-catalyzed condensation of mesityl oxide or acetone with ethyl acetoacetate. -Damascenone(7) was prepared by converting the enone ester 1 into the corresponding tosylhydrazone(4), followed by treating with 4 molar equiv of allyllithium. -Damascenone(12) was synthesized by chemoselective reduction of 1 with sodium borohydride/cerium chloride to give corresponding allylic alcohol 8, conversion of 8 into acetate 9, and thermal decomposition of 9 with DBU to afford ethyl -safranate(10), followed by reaction with an excess amount of allyllithium. -Damascenone(15) was obtained by dehydration of 8 with boric acid to furnish -safranate(13), followed by treatment with 2 molar equiv of allyllithium.

A new technique is presented for generating array factors with arbitrary sidelobe level and envelope taper. Aperture distribution corresponding to simple Taylor Distribution terminates abruptly in a pedestal at its edges. However, generalized Villeneuve distribution with proper excitation at the edges can be used to obtain array factor with desired sidelobe level and envelope tapering. The generalized Villeneuve distribution is obtained by root matching technique. If desired, an additional perturbation technique can be used to obtain more accurate results. A few examples are given to validate the presented method. Also, variation of different array characteristics with respect to sidelobe tapering is explained through graphical data.

Design theory and efficient digital correlator model of a random FM noise radar was presented. The correlator model was developed with System generator blocksets in Simulink environment to include the discrete time base and quantization effect if it can be implemented by using the FPGAs available in the markets. Numerical simulation was conducted with the virtual noise signal and moving target signal generators, and the obtained results show good agreements with the expected values. For an experimental examination, a mm-wave random FM noise radar was implemented based on the obtained design parameters, and a field test was made for detecting a high-speed moving target. With the logging data, an off-line correlation and Doppler processing was made, and the obtained information was very close to the estimated one again. All the results fully validate the design theory and the developed digital correlator model.

There has been an increasing demand for efficient feeding structures in microwave and millimeter-wave circuit and antenna configurations with a goal of providing better performance and easy fabrication. Early the aperture-coupled fed was proposed [1] and has been widely used for many applications due to the advantages of fabrication as well as electrical characteristics [2]. For some phased array applications using a tapered slot antenna as a radiator, an aperture-coupled orthogonal feed technique [3] has been suggested, which enables a robust hybrid configuration combining brick type radiator and a tile type feed network. For an efficient design of such feed structure, micristripline-to-vertically mounted slotline transition has been studied [4].

This study was performed to investigate whether compression/stretching of the spermatic cord or blunt dissection influences testicular development and fertility. In addition, the authors evaluated whether the extents of testicular damage differ between these 2 surgical manipulations.Forty-four prepubertal male Sprague-Dawley (SD) rats (Harlan Sprague-Dawley Inc, Indianapolis, Ind) were divided into 3 groups: (1) the control group (CG) animals underwent a sham operation in the right groin, (2) the experimental group 1 (EG1) underwent compression/stretching of the right spermatic cord, and (3) the experimental group 2 (EG2) underwent dissection around the right spermatic cord structures. Testicular volumes, weights, mean seminiferous tubular diameters (MSTDs), mean testicular biopsy scores, and numbers of offspring and of pregnant females were evaluated.Right (operative) and left (nonoperative) testicular volumes were smaller in the EG2 group than in the CG or EG1 groups. Left MSTDs in the EG1 and EG2 groups increased more than in the CG group. Numbers of Sertoli cells in left testes differed in the 3 groups, in the order EG1CGEG2. Mean testicular biopsy scores, offspring numbers, and pregnant female numbers were no different in the 3 groups.Both surgical manipulations influenced testicular growth, but they did not compromise spermatogenesis or fertility in SD rats.

Purpose: Although the incidence of choledochal cyst (CC) diagnosed in the prenatal or neonatal period is increasing, excision of CC in early infancy is not universally recommended. To validate the rationale of excision of CC in the neonatal period, operative complications and the histologic grade of liver fibrosis at the time of excision of CC were compared in three age groups. Methods: 198 patients who underwent excision of CC, were divided into three age groups, i.e., within 30 days old (group 1, n = 11), 1 to 12 month-old (group 2, n = 40) and over 12 month-old (group 2, n = 147). Retrospective review of their medical records was performed. Results: The overall operative complications were 12 (7 cholangitis, 4 bleeding, 1 ileus). No complication occurred in the group 1. The grade of liver fibrosis had statistically significant positive correlation among groups. Conclusion: Excision of CC in the neonatal period is a safe procedure. The grade of liver fibrosis increased with age. These results support the rationale of early excision of CC.

Purpose In this study, the authors analyzed the effect of experimentally induced gastroschisis on pulmonary hypoplasia in fetal rabbits with congenital diaphragmatic hernia (CDH). Methods Twenty-three pregnant rabbits underwent fetal surgery on gestational day 24 through 27. A left diaphragmatic hernia was created in 1 fetus (DH group) from each rabbit, and a left diaphragmatic hernia with gastroschisis was created in another fetus (GS group). The fetuses were delivered on gestational day 27 through 33. Histologic and morphometric examination of the lungs in each group was done. Results In the DH group, the lungs were hypoplastic with a decrease in lung weight to body weight ratio and an increase pulmonary arterial medial wall thickness. The alveolar septae were markedly thickened with increased interstitial tissue and diminished alveolar air spaces. In the GS group, the alveolar septae were thickened but narrower than those of DH group, and air spaces were increased. The pulmonary arterial wall was markedly thickened in the DH group but only slightly thickened in the GS group. Conclusions Pulmonary hypoplasia seen in newborn rabbits after experimentally induced diaphragmatic hernia is less severe in those rabbits with both gastroschisis and DH.

Background/Purpose: Undifferentiated (embryonal) sarcoma of the liver (USL) is a rare malignancy found in older children, and the most appropriate treatment strategy has been controversial. The authors report the tumor's clinical characteristics and the results of management in 6 children and recommend the best treatment plans based on these findings. Methods: Six USL pathologically verified at Seoul National University Children's Hospital between 1990 and 2000 were reviewed retrospectively. Results: The mean age at diagnosis of USL was 10.3 years (range, 7 to 13 years). There were 2 girls and 4 boys; 5 of 6 children presented with large abdominal mass, one with weight loss. Tumors ranged in size from 8.5 × 9.0 cm to 15.0 × 15.0 cm. Location of the tumor varied from right lobe in 4 to left lobe in one, and both lobes in one. Three children underwent primary complete resection without preoperative chemotherapy. Partial resection of the tumor was done in one child because of encasing inferior vena cava and hepatic vein. However, complete resection was possible at second-look operation after chemotherapy. Two children underwent complete resection after chemotherapy. Preoperative chemotherapy allowed successful resection of 3 USL, which were initially considered unresectable. Postoperative recovery for all children was uneventful. Chemotherapy according to the the Third Intergroup Rhabdomyosarcoma Study (IRS III) was administered to all except one child who refused further postoperative chemotherapy after having had severe complications during the first cycle of chemotherapy. One child with partial resection died of sepsis at 22 months after diagnosis during postoperative chemotherapy after complete surgical removal of the tumor. Five children are alive without recurrence at 40, 45, 48, 60, and 122 months, respectively, after diagnosis. Conclusion: The combined therapy of surgery and chemotherapy in USL can improve the prognosis. J Pediatr Surg 37:1419-1423. Copyright 2002, Elsevier Science (USA). All rights reserved.

Hepatoblastoma is a rare pediatric malignancy that frequently appears in an advanced unresectable stage. Improved resectability and survival rate have been reported with the help of neoadjuvant chemotherapy. Between January 1987 and June 1995 a series of 20 patients were managed with a diagnosis of hepatoblastoma. The median age at diagnosis was 13 months (2 months to 7 years 10 months) with a male/female ratio of 13:7. Chemotherapy effectively reduced the tumor volume (with statistical significance: p = 0.008) and was able to convert seven of nine initially unresectable tumors (78%) to resectable ones. Altogether, 14 operations were done, 12 radical and 2 palliative, with or without adjuvant chemotherapy. The whole population was followed for a median duration of 33 months; and the median survival for the whole group was 26 months. The curative resection group displayed a 5-year survival rate of 61.1%, but none in the noncurative group survived more than 13 months (p = 0.0001). In the univariate analysis for prognostic factors, large tumor size at diagnosis and the absence of thrombocytopenia were associated with poor survival, but these differences were not statistically significant. Pure fetal histology was not associated with better prognosis. In this new era of neoadjuvant chemotherapy, the optimal management strategy for hepatoblastoma is still debated, with radical surgical resection at the earliest possible time being the final goal. For now an individualized approach appears to be the protocol of choice.

To avoid a high-risk operation on a moribund neonate with a ruptured hepatic tumor, transumbilical embolization of the bleeding tumor was attempted in a 2-day-old neonate. A 3F microferret catheter was advanced through the right umbilical artery. After identifying the left hepatic artery feeding the bleeding tumor, Gelfoam (Upjohn, Kalamazoo, MI) particles were injected. Bleeding was successfully controlled. The infant was able to tolerate enteral feeding when stable. Seventeen days after embolization, elective left hepatic lobectomy was performed. Histological examination showed a fetal epithelial type hepatoblastoma. The baby is 13 months old now and is receiving chemotherapy.

Although primary repair is preferred for gastroschisis, this cannot be performed in many patients because of the visceroabdominal disproportion or other accompanying conditions. Several prosthetic materials are used for a silo or patch. When prosthetics are used, staged operations are necessary and infection is an inherent problem. However, these problems can be avoided by using Steridrape for a silo without suturing. The authors used the Steridrape to create a covering for two patients. The eviscerated bowel was irrigated and the abdominal wall was cleansed. A sheet of Steridrape was attached onto the abdominal wall and the herniated viscera was wrapped with it. A second sheet was applied over the first one. Antibiotics were administered and parenteral nutrition was started. The Steridrape covering was changed twice a week. In 1 week the edema subsided remarkably and in 2 weeks the bowel had an almost normal appearance except for hyperemic serosa. Primary repair was performed on the 19th hospital day in patient 1, the 14th day in patient 2. Oral feeding was started 7 days after repair in patient 1, and 22 days after repair in patient 2. Patient 2 developed aspiration pneumonia during transport. Discharge was on the 18th day after surgery in patient 1 and the 50th day in patient 2. The patients are now 18 months and 14 months old, respectively, and are doing well. Steridrape application in gastroschisis is economical, easy to perform, and is a better method to use when transporting the patient. It also facilitates drainage of purulent exudate, and allows the bowel to be inspected easily. This method has proved useful in treating two patients with gastroschisis.

Photoisomerization in monolayers of a azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the generation of azobenzene dendrimer. Charge with trans-cis isomerization was also measured by means of MDC technique.

본 조사 결과는 16개 병원에서 21명의 회원에 의해 수술 받은 환자 71명의 기록과 전체 설문응답지의 대상인 81명에 대한 설문 응답지를 후향적으로 분석한 것으로 자료로서의 정확성에 한계가 있으나 괴사성 장염이라는 질병에 대한 회원들의 전체적인 의견과 성향을 파악하는데 만족할 수 있었으며 회원들이 동일한 관심...