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Colorectal endoscopic submucosal dissection (ESD) remains demanding due to technical difficulties and high risk of perforation. Most of the reported traction methods are initiated after creating a mucosal flap, which is time consuming. To obtain a good visualization at the mucosal incision stage, we developed the early clip-with-line (ECL) method. This method was started immediately after injection of sodium hyaluronate solution into the submucosal layer. In this study, we evaluated the efficacy and the safety of the ECL method for colorectal ESD. We retrospectively analyzed all cases of colorectal ESDs (41 cases in total) performed from January 2017 to February 2019 in our institution. From January 2017 to August 2018, 27 of these cases were performed using conventional (non-ECL) ESDs, while from September 2018 onwards, the remaining 14 cases were performed using the ECL method. Retrospective comparison between the ECL group and the non-ECL group was conducted in terms of clinical characteristics, treatment outcomes, and adverse events. There were no significant differences in clinical characteristics between two groups. Procedure time (median [range]) was significantly shorter in the ECL group than in the non-ECL group (66 [29–131] min vs 90 [30–410] min; P = 0.03). As for adverse events, no case of perforation occurred in the ECL group, whereas perforation was observed in 7.4% (2/27) cases in the non-ECL group (no significant difference). Early clip-with-line method for colorectal endoscopic submucosal dissection reduced procedure time.

Rectal neuroendocrine tumor (RNET) lymphovascular invasion (LVI) is regarded as an important predictor of nodal metastasis after endoscopic resection (ER). However, little is known about the frequency of immunohistochemical detection of LVI in RNETs. This study was performed to establish the actual detection of LVI rate in RNETs ≤10 mm and to evaluate associated clinical outcomes. We retrospectively reviewed the records for 98 consecutive patients treated by ER with a total of 102 RNETs ≤10 mm. Tissue sections were labeled with hematoxylin–eosin (HE) stain, the D2‐40 monoclonal antibody to evaluate lymphatic invasion, and Elastica van Gieson (EVG) stain to detect venous invasion. LVI detection rate by HE versus immunohistochemical analysis was compared. Follow‐up findings and clinical outcomes were also evaluated for 91 patients who were followed for ≥12 months. Lymphatic and venous invasion were detected using HE staining alone in 6.9% and 3.9% of patients, respectively, whereas they were detected using D2‐40 and EVG staining in 20.6% and 47.1% of the patients, respectively. Thus, the LVI detection frequency using D2‐40 and EVG staining (56.9%) was significantly higher than with HE (8.8%). Two out of seven patients who required additional surgery had regional lymph node metastases. However, among the 84 patients who were followed up without surgery, no distant metastases or recurrences were detected. Compared with HE staining, immunohistochemical analysis significantly increased the frequency of LVI detection in RNETs ≤10 mm. However, the clinical impact of LVIs detected using immunohistochemical analysis remains unclear. Clarification of the actual role of LVI using immunohistochemical analysis requires a patient long‐term follow‐up and outcomes.

The mental rotation (MR) task is defined as a discrimination task between mirror-reversed images involving discrepancy in angular orientation. Various studies have shown that the MR task likely causes mental imagery, that is, visual and/or motor imagery, depending on stimulus types. When figures of rotated hands are presented to be identified as a left or right hand, reaction times (RTs) usually show an effect of biomechanical constraints (BC): a hand in a position difficult to reach with a real movement results in longer RTs. The BC effect as a marker of motor imagery has been investigated by brain function measures (fMRI, PET, EEG and MEG) as well as by RTs. Unlike other neuroimaging techniques, NIRS (near-infrared spectroscopy) imposes few physical constraints on participants and is relatively unaffected by motion artifact, which permits serial assessments of tasks in relaxed and natural environment. Focusing on these advantages, a NIRS study on motor imagery in HLJ was carried out in which we measured the brain activation during the HLJ task and a single character judgment task. In the HLJ task, both the RTs and the activity of the left superior parietal lobe (SPL) showed an interaction between Hand (left, right) and Orientation (135°, 225°) i.e., the BC effect, but not in the character judgment task. More specifically, in the analysis of BC-related activity of SPL, although the Hand×Orientation interaction was significant, the left SPL for the left hand significantly increased from 135° to 225°, but the reversed increase (from 225° to 135°) was not found for the right hand. These results suggest that left SPL is involved in the BC effect and NIRS differentiates left hand awkwardness of right-hander in the HLJ task.

Purpose To determine, in the setting of locally advanced pancreatic cancer, the maximum tolerated dose of carbon ion radiation therapy (C-ion RT) and gemcitabine dose delivered concurrently and to estimate local effect and survival. Methods and Materials Eligibility included pathologic confirmation of pancreatic invasive ductal carcinomas and radiographically unresectable disease without metastasis. Concurrent gemcitabine was administered on days 1, 8, and 15, and the dose levels were escalated from 400 to 1000 mg/m2 under the starting dose level (43.2 GyE) of C-ion RT. The dose levels of C-ion RT were escalated from 43.2 to 55.2 GyE at 12 fractions under the fixed recommended gemcitabine dose determined. Results Seventy-six patients were enrolled. Among the 72 treated patients, dose-limiting toxicity was observed in 3 patients: grade 3 infection in 1 patient and grade 4 neutropenia in 2 patients. Only 1 patient experienced a late grade 3 gastric ulcer and bleeding 10 months after C-ion RT. The recommended dose of gemcitabine with C-ion RT was found to be 1000 mg/m2. The dose of C-ion RT with the full dose of gemcitabine (1000 mg/m2) was safely increased to 55.2 GyE. The freedom from local progression rate was 83% at 2 years using the Response Evaluation Criteria in Solid Tumors. The 2-year overall survival rates in all patients and in the high-dose group with stage III (≥45.6 GyE) were 35% and 48%, respectively. Conclusions Carbon ion RT with concurrent full-dose gemcitabine was well tolerated and effective in patients with unresectable locally advanced pancreatic cancer.

In this research, as a different approach to the conventional one which enhances the performance with hardware of a haptic device, we adopt another approach to make the brain feel as if the person is touching the real thing via an illusion. Thus, we study Velvet Hand Illusion (VHI) which is an illusionary phenomenon concerning tactile touch. In VHI, a hexagonal wire mesh is sandwiched between both hands and rubbing the wire mesh without relative motion between both hands generates a smooth feeling, like velvet. The brain activation at this time is measured by PocketNIRS, which contains two channels measuring the bilateral prefrontal cortex. We obtained the result that the prefrontal cortex was activated to roughly two times larger when VHI occurred than when touching real velvet fabric. Since different responses can be obtained in the prefrontal cortex during brain activation between real velvet and VHI, it is possible to use pocketNIRS for the evaluation of VHI.

To examine the mechanism of visual perception of human-like body postures, we conducted a posture recognition task, a questionnaire survey, and the Interpersonal Reactivity Index (IRI). The majority of participants perceived the pseudo-posture as a human posture in the early stage (78%), but only approximately half of them reported the imagination of bodily movement (66%). These results suggest that the majority of observers perceive pseudo-postures as human postures in the early stage of perception, but this human posture perception does not necessarily lead to the visualisation of bodily movement. In a group of who received the pseudo posture as a human-posture regardless of the perception stages, the participants who imagined bodily movement (64%) showed significantly higher scores than those who did not on the Fantasy subscale of the IRI. Highly empathic participants are more likely to detect a kinematic relation between the pseudo-postures.

Interpersonal interaction can be classified into two types: concurrent and turn-based interaction, requiring synchronized body-movement and complementary behaviors across persons, respectively. To examine the neural mechanism of turn-based interaction, we simultaneously measured paired participants activations in their bilateral inferior frontal gyrus (IFG) and the bilateral inferior parietal lobule (IPL) in a turn-taking game using near-infrared spectroscopy (NIRS). Pairs of participants were assigned to either one of two roles (game builder and the partner) in the game. The builder’s task was to make a copy of a target disk-pattern by placing disks on a monitor, while the partner’s task was to aid the builder in his/her goal (cooperation condition) or to obstruct it (competition condition). The builder always took the initial move and the partner followed. The NIRS data demonstrated an interaction of role (builder vs. partner) by task-type (cooperation vs. competition) in the right IFG. The builder in the cooperation condition showed higher activation than the cooperator, but the same builder in the competition condition showed lower activation than in the cooperation condition. The activations in the competitor–builder pairs showed positive correlation between their right IFG, but the activations in the cooperator–builder pairs did not. These results suggest that the builder’s activation in the right IFG is reduced/increased in the context of interacting with a cooperative/competitive partner. Also, the competitor may actively trace the builder’s disk manipulation, leading to deeper mind-set synchronization in the competition condition, while the cooperator may passively follow the builder’s move, leading to shallower mind-set synchronization in the cooperation condition.

The right inferior frontal gyrus (IFG) is involved in intention understanding during interpersonal interactions. To examine how prior experience of cooperation and competition affects one's right IFG activation in the subsequent interaction, using near-infrared spectroscopy (NIRS) we simultaneously measured paired participants' bilateral IFG activations during a turn-taking game. Participant pairs were assigned to either one of two roles: a Builder taking the initial move to copy a target disk-pattern on monitor and the Partner taking the second move to aid in (cooperation) or to obstruct (competition) the Builder. The experiment consisted of two sessions. One participant (B-P) played as a Builder (B-) in session 1 and changed the role to the Partner (-P) in session 2, and vice versa for the paired participant (P-B). NIRS data in competition demonstrated that the Builder (B-) being obstructed in session 1 showed higher right IFG activation when (s)he took a role of obstructor (-P) in session 2 (the obstructed effect), whereas "the cooperated effect" was not revealed in cooperation. These results suggest that prior experience of being obstructed may facilitate understanding of the Builder and/or the obstructor's tactical move, thereby increasing his/her right IFG activation when one is meant to obstruct in subsequent competitions.

A 77-year-old men with abdominal pain suffered from gall bladder hemorrhage and liver abcess was admitted for intensive care of severe acute cholangitis. He had hemobilia which was treated by the endoscopic retrograde bile duct drainage. After 2 months treatment with rest for purulent myelitis, he had neoplastic change of liver abcess diagnosed as intrahepatic bile duct cancer by percutaneous core needle biopsy. He underwent surgery as central bisegmentectomy and left the hospital at home 3 months later after rehabilitation for surgical site infection. He noticed growing mass on right chest 6 months later after hepatectomy and was diagnosed as needle tract implantation in chest wall by CT examination. Pathological exam revealed cholangiocarcinoma by radical excision. He have disease free for 5 years after second operation. Although percutaneous biopsy for hepatic tumor increases risks of needle tract implantation and dissemination, there is an advantage of radical resection for tract implantaion.

We examined how a friend’s presence affects a performer’s prefrontalactivation in daily-life activities using two wireless portable near-infrared spectroscopy(NIRS) devices. Participants played a driving video game either solely in the singlegroup or with a friend in the paired group. The two groups (single and paired) weresubdivided according to their game proficiency (low and high). The NIRS data dem-onstrated a significant interaction of group by proficiency. Low-proficiency players inthe paired group showed lower activation than those in the single group, but high-proficiency players did not. In the paired group, high-proficiency players showedhigher activation than low-proficiency players, but not in the single group. Theseresults suggest that NIRS detects social presence effects in everyday situations:decreasing prefrontal activation in low-proficiency performers due to tension reduc-tion and increasing prefrontal activation in high-proficiency performers due toincreased arousal.Key words: presence of others, near-infrared spectroscopy (NIRS), online monitor-ing, prefrontal cortex (PFC), task proficiency.The presence of others (PO) affects an indi-vidual’s mind and performance widely in dailyactivities (Allport, 1924),such as sports,in-classlearning, group work, and playing games.Accordingly, a critical question arises: How canwe predict whether PO will improve or impairour solitary performance? Because of its funda-mental importance on human development andbehavior (Allport, 1954),the effects of PO haveattracted great interest for both theoretical andapplied research for several decades (Aiello D Uziel, 2007).The social presence effects have been previ-ously studied in two main research fields.Socialfacilitation literature suggests that PO (strangeror friend) generally improves well-learnedtasks and impairs poorly learned tasks as asource of arousal (Zajonc, 1965, 1980). That is,PO generally increases an individual’s arousal,which in turn enhances emission of a habitualresponse from his/her behavioral repertoire. Ina well-learned task, the habitual response isusually the correct one, leading to performanceimprovement,whereas in a poorly learned task,it is usually the incorrect one, leading to perfor-mance impairment.In contrast, social support research has con-sistently revealed that PO does not always func-tion to increase one’s tension; the presenceof a friend may relax an individual in stressful

Exposed crystal face-controlled brookite titanium(IV) oxide (TiO2) nanorods with various aspect ratios were prepared by a hydrothermal process with or without PVA or PVP as an aspect reagent. The nanorod-shaped brookite TiO2 had larger {2 1 0} and smaller {2 1 2} exposed crystal faces, which were assigned by TEM with the SAED technique. Their aspect ratios were greatly influenced by the addition of PVA or PVP as an aspect ratio control reagent to the reaction solution used in the hydrothermal treatment. The photocatalytic activity for decomposition of acetaldehyde increased with increase in the aspect ratio because the surface area ratio of {2 1 0} to {2 1 2} exposed crystal faces, which are attributed to reduction and oxidation sites, respectively, became more optimal. The {2 1 2} exposed crystal faces of surface-controlled brookite TiO2 were site-selectively modified with trivalent iron(III) (Fe3+) ions by utilizing the adsorption property of iron(III)/iron(II) (Fe3+/Fe2+) ions. The brookite TiO2 nanorod with site-selective modification of Fe3+ ions showed much higher photocatalytic activity than that of commercial brookite TiO2 loaded with Fe ions under visible-light irradiation because of the separation of redox sites. In other words, oxidation and reduction proceed over Fe3+ ion-modified {2 1 2} faces of the TiO2 surface and on {2 1 0} faces of the TiO2 surface without modification of Fe3+, respectively.

Photocatalytic reduction of carbon dioxide (CO 2 ) was carried out using exposed-crystal- face-controlled titanium(IV) oxide (TiO 2 ) having a brookite phase. Methanol (CH 3 OH) was detected as the main product, and trace amounts of formic acid, carbon monoxide, methane, and hydrogen were also detected in some cases. The prepared nanorod-shaped brookite TiO 2 with large {2 1 0} and small {2 1 2} exposed crystal faces showed larger CH 3 OH generation than that of commercial brookite TiO 2 powder (Kojundo Chemical Laboratory Co., Ltd.). The activity of a brookite TiO 2 nanorod for CO 2 reduction depended on its aspect ratio because the {2 1 0} crystal faced worked as a reduction site, whereas an oxidation site was assigned to {2 1 2} crystal faces. Photodeposition of gold (Au) or silver (Ag) nanoparticles on the nanorod-shaped brookite TiO 2 induced a dramatic increase in CH 3 OH production because the deposited metal particles work as reductive sites for multi-electron reduction of CO 2 . Among the co-catalyst-loaded brookite TiO 2 nanorods, nanorod-shaped brookite TiO 2 loaded with Ag showed higher activity. The source of carbon of CH 3 OH obtained by CO 2 reduction is discussed on the basis of results of a labeling experiment using 13 CO 2 .

We evaluated a transparent PI film as a cell culture sheet in comparison with films of PA and PEEK formed, which have been previously used in cell culture sheets. We fabricated microtrenches with a width and depth of 5 μm on these polymer films by hot embossing, and then cultivated OP9 stromal marrow cells on the sheets. The cells grown on the transparent PI were easily observed using an optical microscope.

The research on stem cell cultures has attracted much attention due to the recent development of regenerative medicine. Therefore, higher functionalities for devices used for culturing cells are strongly demanded. In this study, we fabricated cell culture sheets using transparent polyimide (PI), parylene (PA), and polyetheretherketone (PEEK) to make polymer materials that had microstructures. We then cultured stromal marrow cells (OP9) on them and investigated the cell alignment within the microstructures. Hot embossing was used to fabricate the microstructures with a width and depth of 5 μm on the polymer substrates. Cultivation of the cells was confirmed on the transparent PI and PA sheets, however, it was not observed on the PEEK sheet. Slight alignment of the cells was also observed along with the microstructures.

Previous studies have reported that the mirror neuron system plays a crucial role in social cognition. We examined whether the higher-order cognitive functions are involved in the activations in the mirror neuron area when we perceive simplified pseudo-postures. We measured 14 participants’ brain activation during the posture-recognition task using near-infrared spectroscopy. The participants’ task was to observe five sequentially presented target pseudo-postures and judge whether a test pseudo-posture was identical to one of the preceding five target pseudo-postures. The results in the majority of participants (n = 10/14) revealed that the activity in the inferior frontal mirror neuron area is modulated by perception of human-likeness, but not in the remaining four participants (n = 4/14). These results suggest that the degree of the activation of higher-order cognitive functions, which may be engaged in the inhibitory and/or facilitative processing of human body or bodily movement, leads to the distinctive activities in the inferior frontal mirror neuron area.

In this paper, novel fabrication processes for flexible, semi-transparent, and nano-meshed Au electrodes on polyethylene terephthalate (PET) substrate utilizing transfer printing from self-organized polymer mold are described. A polycarbonate mold with honeycomb meshed structures was fabricated by a solvent casting method to form self-organized arrays of water bubbles and by drying the water bubbles. It was succeeded to transfer Au electrodes on PEDOT:PSS coated PET substrates using the Au-coated mold under the pressure of 1 MPa at 100 oC for 10 min. The transferred Au mesh has a line-width of 350 nm, a period of 1.5 μm, and a depth of 1.75 μm. The measured transmittance of Au mesh electrode was 34%, and it was less than half of that of an ITO electrode on PET substrate (75%) at photon wave length of 500 nm. However, the measured sheet resistance of the Au mesh electrode is 3 Ω/□, and it was 11 times lower than that of the ITO (33 Ω/□).

To examine the neural mechanism of co-speech gesture production, we measured brain activity of bilinguals during an animation–narration task using near-infrared spectroscopy. The task of the participants was to watch two stories via an animated cartoon, and then narrate the contents in their first language (Ll) and second language (L2), respectively. The participants showed significantly more gestures in L2 than in L1. The number of gestures lowered at the ending part of the narration in L1, but not in L2. Analyses of concentration changes of oxygenated hemoglobin revealed that activation of the left inferior frontal gyrus (IFG) significantly increased during gesture production, while activation of the left posterior superior temporal sulcus (pSTS) significantly decreased in line with an increase in the left IFG. These brain activation patterns suggest that the left IFG is involved in the gesture production, and the left pSTS is modulated by the speech load.

The lithium-ion secondary batteries have been widely used for the space programs, today. Among them, REIMEI was one of the first satellites using lithium-ion secondary battery. In 2005, the satellite was launched, and injected into the low earth polar orbit. Eleven years has passed since the launch and over 60,000 cycles of charge and discharge was experienced in space. The lithium-ion secondary cell of the REIMEI battery was designed using spinel manganese oxide type material for the positive electrode, and the graphitized type carbon for the negative electrode. The cell case was made of aluminium laminated film and the structure was reinforced by the epoxy resin and aluminium housing. After the operation of eleven years, the cells still maintain the appropriate uniform balance and operative. In order to identify the internal condition of the battery/cell, we calculated the ac impedance by the pulse duration to the on-board battery.

Flexible micropumps are important components for advanced microfluidic systems. Here, polyimide (PI) for flexible micropumps was focused on. This is because PI has many advantageous properties such as good biocompatibility, high thermal stability, and superior mechanical strength. However, the difficulty in realizing an all-PI micropump lies in fabricating microstructures on PI film surfaces. In this paper, we present improved performances of a flexible all-PI micropump fabricated using high-temperature hot embossing above 320 oC that is considerably higher than its glass transition temperature of 275 oC. The fabricated micropump had diffuser/nozzle valves and a chamber with 5 mm diameter, and it was functioned by vibrating a 2-µm-thick PI diaphragm with alternating air pressures outside of the diaphragm. The flow rate of deionized water in the micropump reached to 110 μl/min at 3 Hz.

Air-actuated valveless micropumps with dual polyimide (PI) diaphragms have been fabricated and characterized. A 5-μm-thick PI membrane was spin-coated on Si wafer, and released by Si ICP etching. The membrane was actuated by alternating air pressure of 10 kPa. The water flow-rate achieved 80 μl/min at the frequency of 1 Hz and 126 μl/min at 3Hz. Due to nice adhesion between Si and polyimide diaphragms, we could fabricate the double diaphragm micropumps with simplified fabrication processes.

Transfer printing of Au micro-electrode patterns onto a polyimide (PI) film was investigated, and the optimum transfer conditions were obtained. Here, the line and space patterns with widths of 25 μm and 100 μm were successfully transfered on polyimide films at a molding temperature of 150 °C for 3 min under the molding pressure of 2.5 MPa. This technique is expected to provide simplified processes to fabricate electrode patterns on microelectro mechanical systems (MEMS).

Improved fabrication processes of an all-polyimide micro electroosmotic flow pump using hot embossing are described. Microchannels in the micropump were fabricated by hot embossing on a transparent polyimide substrate. A silicon micromachined mold was pressed into the transparent polyimide substrate at a temperature of 300 oC to form microchannel patterns on the substrate. The depth and width of the microchannels were 25 μm and 50 μm, respectively. A UV ozone treatment was performed to improve adhesion between the transparent polyimide substrate and film capping layer. This UV ozone treatment enhanced adhesion and resulted in the reduction of the adhesion temperature as low as 100 oC, and nearly no deformation of the microchannels was observed. As a result, the electroosmotic flow pump exhibited the flow rate of 0.7 μl/min when a voltage of 50 V was given between the electrodes separated 20 mm each other.

Improved fabrication processes of a micro electroosmotic flow pump using hot embossing are described. The microchannels in the micropump were fabricated by hot embossing on a polymethylmethacrylate (PMMA) substrate. A silicon micromachined mold was pressed into the PMMA substrate at a temperature of 145 °C to form microchannel patterns on the substrate. The depth and width of the microchannels were 50 μm and 100 μm, respectively. Aluminum electrodes were deposited using thermal vacuum deposition. A UV ozone treatment was performed to improve adhesion between the PMMA substrate and a PMMA capping layer. This UV ozone treatment enhanced adhesion and resulted in the reduction of the adhesion temperature as low as 70 °C, and nearly no deformation of the microchannels was observed. As a result, the electroosmotic flow pump exhibited the flow rate of 0.5 μl/min when a voltage of 50 V was given between the electrodes separated 8 mm each other.

We herein report the histopathology of a rare case of an idiopathic internal mammary artery aneurysm in a 61-year-old asymptomatic woman. Chest radiography during an annual medical check-up incidentally revealed the aneurysm, which was initially mistaken for a mediastinal tumor. Given that a rupture of the aneurysm could have been life-threatening, it was removed surgically, and found to possess a paper-thin arterial wall with cystic medial degeneration.

We used functional near-infrared spectroscopy to investigate the role of the dorsolateral prefrontal cortex of bilinguals in semantic processing. Chinese-Japanese bilinguals and Japanese monolinguals judged if visually presented pairings of a word and a definition were Japanese. The four types of pairs appeared in Japanese and/or Chinese dictionaries: both, Japanese-specific, Chinese-specific, and neither. The bilinguals showed greater oxy-hemoglobin concentrations in their left dorsolateral prefrontal cortex for the Chinese-specific pair, while those in its right homologue were greater for the Japanese-specific, the Chinese-specific, and the neither pairs. These results imply that in the bilinguals, the left dorsolateral prefrontal cortex is related to reducing activation of semantic information in the nontarget language, while its right homologue focuses attention on the target language.

The organic acid-based crosslinkers trisuccinimidyl citrate (TSC), disuccinimidyl malate (DSM), and disuccinimidyl tartarate (DST) were combined with human serum albumin (HSA) to produce biodegradable solid— liquid-type adhesives, TSC-A, DSM-A, and DST-A. The bonding time of TSC-A, DSM-A, and DST-A was 15, 10, and 5 min, respectively, when the content of organic acid-based crosslinkers was 0.5 mmol and the HSA concentration was 44 w/v%. Five minutes after application of the adhesives, the DST-A adhesive had the greatest bonding strength (489.14 ± 93.06 kPa) compared with TSC-A (120.86 ± 73.83 kPa) and DSM-A (224.44 ± 79.53 kPa). The bonding strength of DSM-A and DST-A increased with increasing DSM or DST content up to 0.5 mmol, after that the bonding strength decreased. While, the bonding strength of the TSC-A adhesive was relatively low at any TSC content compared with the other adhesives. The bonding strength of DST-A with 0.3 mmol of DST increased with increasing HSA concentration up to 44 w/v%, and then decreased. The bonding strength of the DST-A adhesive was 3.2-fold greater than that of a commercial aldehyde-based adhesive and 6-fold greater than that of a fibrin-based adhesive. DST-A has excellent biocompatibility, bioabsorbability, and only mild tissue reaction in rat subcutaneous tissues.

本研究は，非均衡型の2言語併用者が，第2言語(second language: L2)の意味処理を求められた際に，第1言語(first language: L1)の意味処理を抑制し得るか否かを，語釈判断課題を用いて検討した．L2の熟達度が異なる2群(high vs. low: H/L)の2言語併用者と，日本語を第1言語とする1群の単言語使用者(Japanese: J)が，視覚呈示された日中同形語と語釈の対を「日本語として知っているか」否かの判断を遂行した．語と語釈のセットは，日本語と中国語の辞書の片方か，あるいは両方に記載されているか否かに応じて，日中で「共通」，「日本語固有」，あるいは「中国語固有」の3種類に分類された．共通と日本語固有語釈に対する既知反応(正答)率では，3群間に差が認められなかった．これに対して，中国語固有語釈に対する既知反応(誤答)率では，L群はJ群よりも高い値を示し，H群はJ群よりも高い値を示す有意な傾向が認められた．これらの結果は，L2の意味処理を要求されると，H群は，L1の意味処理をほぼ抑制し得るのに対して，L群は，L1の意味処理を抑制し得ないことを示す．このことは，非均衡型の2言語併用者の意味処理が，L2の熟達度の上昇に応じて，言語非選択的から選択的に変化すると結論づけられる．