Search

Co-infection with cryptococcus and tuberculosis has rarely been reported. We herein report a case of an 80-year-old man with cryptococcal pleuritis concurrent with pulmonary tuberculosis. He was admitted for progression of left pleural effusion and consolidation in the left upper lobe. Culture for Mycobacterium tuberculosis was positive in sputum, and analyses of pleural effusion revealed lymphocyte-predominant high levels of adenosine deaminase (ADA). Medical thoracoscopy revealed massive infiltration of Cryptococcus neoformans in pleura without granuloma. This is the first case report of cryptococcal pleuritis coincident with pulmonary tuberculosis. Cryptococcal pleuritis should be ruled out when the adenosine deaminase levels are elevated in pleural effusion.

The demand for single photon emitters at λ=1.54 μm, which follows from the consistent development of quantum networks based on optical fiber technologies, makes Er:O

Endothelial cells (EC) are involved in regulating several aspects of lipid metabolism, with recent research revealing the clinicopathological significance of interactions between EC and lipids. Induced pluripotent stem cells (iPSC) have various possible medical uses, so understanding the metabolism of these cells is important. In this study, endothelial phenotype cells generated from human iPSC formed cell networks in co-culture with fibroblasts. Changes of plasmalogen lipids and sphingomyelins in endothelial phenotype cells generated from human iPSC were investigated by reverse-phase ultra-high-pressure liquid chromatography mass spectrometry (UHPLC-MS/MS) analysis. The levels of plasmalogen phosphatidylethanolamines (38:5) and (38:4) increased during differentiation of EC, while sphingomyelin levels decreased transiently. These changes of plasmalogen lipids and sphingomyelins may have physiological significance for EC and could be used as markers of differentiation.

It has been reported that erbium (Er) is a source of optical emission at λ=1.54 pm due to 4I 13/2 →4I 15/2 transition of Er3+. A method of oxygen (O) codoping with Er has attracted attention as a candidate for obtaining more efficient optical gain by forming Er:O complex. Although several simulations predict the equilibrium structure of Er:O complex, it is difficult to understand experimentally how related between these implanted ions followed by annealing for optical activation. In this workshop, we reported the preliminary results on three-dimensional distributions of Er and O co-implanted into Si investigated by atom probe tomography.

Luminescence of erbium in silicon has been intensively explored in the past in the high power emission regime, but its employment for manufacturability of active components for silicon photonics proved unfeasible. We explore the room-temperature photoluminescence (PL) at the telecomm wavelength of very low implantation doses of ErO x in Si for accessing few photon regime towards single photon emission. We achieve countable photon regime and we assess the lower-bound number of detectable emission centers by micron scale implanted dots, whose emission is collected by an inverted confocal microscope.

The diffusion coefficient and the solubility limit of copper in ferromagnetic iron were directly measured using atom probe tomography at lower temperatures than in previous studies. Cu–Fe diffusion couples were annealed at temperatures from 550 to 750 °C. The diffusion coefficient was determined to be D = 0.48 exp(−Q/kBT) m s−1 (Q = 3.22 eV), which, below 650 °C, is about 1.3 times higher than the extrapolation from a previous study considering the magnetic effect. The measured Cu solubility limit is in good agreement with literature.

We have shown that the structural and compositional properties of semiconductor interfaces fabricated by surface activated bonding (SAB) would be modified during focused ion beam (FIB) processes operated at room temperature (RT), especially for wide band-gap materials, and such a modification can be suppressed by FIB processes operated at lower temperatures. During FIB processes operated at RT, SAB-fabricated Si/Si and GaAs/GaAs interfaces are amorphized along the interfaces, even at the internal locations deeper than the penetration depth of the FIB, and the impurity distribution across the interfaces is modified. This phenomenon is presumably due to the atomic diffusion assisted by the point defects that are introduced by FIB irradiation. By using FIB processes operated at −150 °C, the FIB-induced atomic diffusion would be ignored for Si/Si interfaces. Meanwhile, the diffusion would be still effective for GaAs/GaAs interfaces, presumably due to the effects of recombination-enhanced defect motion under FIB irradiation.

Direct bonding of diamond and Cu was successfully fabricated by surface activated bonding (SAB) method at room temperature. The interfacial structure of the diamond/Cu bonding interface was investigated by transmission electron microscope (TEM) and electron energy-loss spectroscopy (EELS). The effect of heat treatment temperature on the interface structure was also investigated. 4-nm-thick damaged layer was formed at the as-bonded interface, the damaged layer thickness decreased with annealing temperature rise. It was found that the atomic ratio of sp2 bonding in the bonding interface was larger than that of the diamond separated from the interface by approximately 50 nm, which indicated that the damaged layer was composed of the amorphous or graphite and diamond. After annealing at 700 ℃, a composite layer of about 2 nm thick was observed at the interface. There were no nanovoids and micro-cracks observed at the interface with annealing at a temperature as high as 700 ℃. These results indicated that the diamond/Cu bonding interface has high thermal stability and can withstand the temperature rise of power devices during operating.

Article, Autism & Developmental Language Impairments. 4: 1-12. (2019)

Elemental analysis can be applied in the medical field to investigate the causes of disease. In patients with some pulmonary diseases, elements can be found in the exogenous dust deposited in the lungs and are also accumulated through the loss of cell homeostasis. Diseases induced by inhalation of dust typically affect the lungs. Although there are many pulmonary diseases induced by dust inhalation, it is often difficult to clarify the exact cause. In-air microparticle induced X-ray emission (in-air micro-PIXE) analysis is a method of elemental analysis that employs a proton ion-beam to directly measure the content of elements and their distribution in frozen sections or paraffin sections of tissue. We constantly inhale particles while breathing, but most of us do not develop pulmonary disease. Because in-air micro-PIXE analysis can determine the two-dimensional localization and content of particles in tissue, we can clarify the relationship between inhaled particles and diseases based on such analysis and the immunohistochemical expression of disease-related proteins. Elemental analysis methods like in-air micro-PIXE analysis may be useful for making precise diagnosis amd assesing disease progression to overcome threat such as occupational or environmental exposure.

To evaluate dislocations induced by neutron irradiation, we developed a weak-beam scanning transmission electron microscopy (WB-STEM) system by installing a novel beam selector, an annular detector, a high-speed CCD camera and an imaging filter in the camera chamber of a spherical aberration-corrected transmission electron microscope. The capabilities of the WB-STEM with respect to wide-view imaging, real-time diffraction monitoring and multi-contrast imaging are demonstrated using typical reactor pressure vessel steel that had been used in an European nuclear reactor for 30 years as a surveillance test piece with a fluence of 1.09 × 1020 neutrons cm-2. The quantitatively measured size distribution (average loop size = 3.6 ± 2.1 nm), number density of the dislocation loops (3.6 × 1022 m-3) and dislocation density (7.8 × 1013 m m-3) were carefully compared with the values obtained via conventional weak-beam transmission electron microscopy studies. In addition, cluster analysis using atom probe tomography (APT) further demonstrated the potential of the WB-STEM for correlative electron tomography/APT experiments.

The relationship between the laser power and the three-dimensional distribution of boron (B) in silicon (Si) measured by laser-assisted atom probe tomography (APT) is investigated. The ultraviolet laser employed in this study has a fixed wavelength of 355 nm. The measured distributions are almost uniform and homogeneous when using low laser power, while clear B accumulation at the low-index pole of single-crystalline Si and segregation along the grain boundaries in polycrystalline Si are observed when using high laser power (100 pJ). These effects are thought to be caused by the surface migration of atoms, which is promoted by high laser power. Therefore, for ensuring a high-fidelity APT measurement of the B distribution in Si, high laser power is not recommended.

cited By 4; International audience; Single planes of Si nanocrystals (NCs) embedded in a SiO2 matrix were synthesized by annealing SiO2/SiO/SiO2 multilayer structures deposited on Si (100) substrates by e-beam evaporation. The dependence of the shape, size, and areal density of Si NCs on the thickness of the initial SiO layer was investigated using atom probe tomography and validated by energy filtered transmission electron microscopy. Three kinds of samples were prepared with SiO layer thicknesses of 4, 6, and 10 nm. The size of Si NCs enlarged with increasing SiO layer thickness. The shape of Si NCs was mainly extended spheroid in all three kinds of samples. In the sample with the 4 nm-thick SiO layer, the Si NCs were more prolate than those in the other two samples. Moreover, many rod-shaped Si NCs appeared in the sample with the 10 nm-thick SiO layer. These rod-shaped Si NCs were found to be connected by small Si NCs. The areal densities of Si NCs were in the order of 1012 NCs per cm2 in all samples. © 2016 The Royal Society of Chemistry.

Airway inflammation is accompanied by infiltration of inflammatory cells and an abnormal response of airway smooth muscle. These cells secrete chemokines and express the cell surface chemokine receptors that play an important role in the migration and degranulation of inflammatory cells. Omalizumab is a monoclonal antibody directed against immunoglobulin E, and its blocking of IgE signaling not only reduces inflammatory cell infiltration mediated by the Th2 immune response but also inhibits other immune responses. The chemokine CCL15 is influenced by omalizumab, and the source of CCL15 has been reported to be airway smooth muscle cells and basophils. CCL15 binds to its receptor CCR1, which has been reported to be expressed by various inflammatory cells and also by airway smooth muscle cells. Therefore, CCL15/CCR1 signaling could be a target for the treatment of asthma. We review the role of CCL15 in the pathogenesis of asthma and also discuss the influence of IgE-mediated immunomodulation via CCL15 and its receptor CCR1.

An 81-year-old Japanese man had organizing pneumonia (OP), and he had worked as a painter and had a history of exposure of various paints over 20 years. The major features on computed tomography (CT) in patients were cryptogenic organizing pneumonia (COP) showing airspace consolidation, and air bronchograms were consistent finding in consolidation in right lung of S¹⁰. Such parenchymal abnormalities were clinically and pathologically diagnosed COP and the lesion was improved by corticosteroid therapy. About 1.5 years later, similar shadows emerged in new locations of right S⁴ and left S⁸, and these were bronchioloalveolar carcinoma (BAC) classified as adenocarcinoma. BAC causes similar X-ray changes to COP and inflammation accompanying BAC can also respond to corticosteroids, which may lead to delay in the diagnosis of BAC associated with COP. These radiological features lead to difficulty in making a diagnosis of new parenchymal diseases. The present patient had been painter, and metals of carcinogens were proven in both tissue of COP and BAC. Here, we reported a painter with COP and new-onset BAC who had been exposed to particles proven by elemental analysis. The combination of COP with BAC is considered uncommon, but the risk of BAC may increase when there is a history of particle inhalation.

Although HIV-1 replication can be controlled by highly active anti-retroviral therapy (HAART) using protease and reverse transcriptase inhibitors, the development of multidrug-resistant viruses compromises the efficacy of HAART. Thus, it is necessary to develop new drugs with novel targets. To identify new anti-HIV-1 compounds, recombinant Vpr was purified from transfected COS-7 cells and used to screen compounds by chemical array to identify those that bound Vpr. From this screen, 108 compounds were selected as positive for Vpr binding. Among these, one structurally similar group of four compounds showed anti-HIV activity in macrophages. In particular, compound SIP-1 had high inhibition activity and reduced the levels of p24 by more than 98% in macrophages after 8 or 12 days of infection. SIP-1 had no cytotoxic effects and did not disrupt cell cycle progression or induce apoptosis of Molt-4 and HeLa cell lines as measured by MTT assay, flow-cytometry analysis, and a caspase-3 assay. In addition, SIP-1 specifically bound to Vpr as assessed by photo-cross-linked small-molecule affinity beads. These results suggest that Vpr is a good target for the development of compounds that could potentially inhibit HIV-1 replication. Collectively, our results strongly suggest that chemical array is a useful method for screening anti-viral compounds.

Atom probe tomography and secondary ion mass spectrometry were used to investigate the effects of carbon (C) co-implantation and subsequent annealing at 600 to 1200 °C on the behavior of implanted boron (B) atoms in silicon. When B alone was implanted, annealing at 600 to 800 °C caused it to form clusters in the peak region (1020 cm−3) of the concentration profile, and diffusion only occurred in the low-concentration tail region (

Polycrystalline materials with grain boundaries (GBs), involving excess free energy because of their structural imperfection, can reduce their energy by the nanoscopic structural changes of the GBs via impurity segregation. Those local changes at GBs can stabilize non-equilibrium nanostructures, resulting in the drastic change in the macroscopic properties of those materials. The mechanism of GB segregation is, however, far from being understood due to difficulties in characterizing both crystallographic and chemical properties of the same GB at atomistic levels. We have therefore developed an analytical method to determine the impurity segregation ability on the same GB at the same nanoscopic location by a joint use of scanning transmission electron microscopy (STEM) and atom probe tomography (APT) combined with ab-initio calculations, and discussed the segregation mechanism in terms of bond distortions at the GB. In the present work, we examined the GBs in Si ingots used for solar cells. They have serious impacts on the solar cell efficiency via the segregation of detrimental impurity atoms, such as oxygen and transition metals introduced inevitably during crystal growth and cell processing, depending on their structural condition at those GBs. Accordingly, precise understanding of the segregation mechanism of impurity atoms is one important issue to produce cost-effective solar cells by engineering the structural condition of impurity atoms segregating at GBs. Three-dimensional distribution of impurity atoms was systematically determined at the typical large-angle GBs (i.e., Σ3{111}, Σ5{013}, Σ9{221}, Σ9{114}, Σ9{111}/{115}, and Σ27{552}) [1-3] and small-angle GBs [3-5] by APT with a low impurity detection limit (0.01 at.% on a GB plane) simultaneously with a high spatial resolution (about 0.4 nm), and it was correlated with the atomic stresses around the GBs estimated by ab-initio calculations based on atomic-resolution scanning TEM data (for large-angle GBs [2]) and by calculations with the elastic theory based on dark-field TEM data (for small-angle GBs [4]). It was hypothesized that oxygen atoms segregate at the bond-centered positions under tensile stresses above about 2 GPa so as to attain more stable bonding network by reducing the local stresses [6]. The number of segregating atoms per unit GB area (N GB ) is in proportion to both the number of the stressed positions per unit GB area (n bc) and the average concentration of oxygen atoms around the GB ([Oi]) with N GB ~ 50n bc[Oi]. This indicates that the probability of oxygen atoms at the segregation positions would be, on average, fifty times larger than in bond-centered positions in defect-free regions. This nanoscopic finding may provide a general guidance to control compositions and band structures at GBs via oxygen segregation. References: [1] Y. Ohno, et al., Appl. Phys. Lett. 103 (2013) 102102; [2] Y. Ohno, et al., Appl. Phys. Lett. 110 (2017) 062105; [3] Y. Ohno, et al., Appl. Phys. Lett. 109 (2016) 142105; [4] Y. Ohno, et al., Appl. Phys. Lett. 106 (2015) 251603; [5] Y. Ohno, et al., Phys. Rev. B 91 (2015) 235315; [6] Y. Ohno, et al., J. Microsc. 268 (2017) 230. Acknowledgments: This work was supported by “Multicrystalline informatics toward establishment of general grain boundary physics & realization of high-quality silicon ingot with ideal microstructures” in “Revolutional material development by fusion of strong experiments with theory/data science” project in JST/CREST, Grant No. JPMJCR17J1 (2017-2023). STEM and APT were, respectively, performed at ISIR under the Cooperative Research Program of "Network Joint Research Center for Materials and Devices: Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials" and at The Oarai Center under under the Inter-University Cooperative Research Program in IMR. Figure caption: Analyses of oxygen segregation at large-angle GBs in Si [2]. (a, c) Bonding network and (b, d) distribution of atomic stress P atomic at (a, b) Σ9{221} and (c, d) Σ9{114} GBs. (e, f) Number of bond-centered positions under a tensile stress P bc above 1.5 GPa and (g, h) oxygen density across the GB plane for (e, g) Σ9{221} and (f, h) Σ9{114} GBs. Figure 1

Hydrogen (H) plays an important role in determining the reliability and performance of HfO2- and Al2O3-based high-k dielectric electronic devices. In order to understand H behavior, deuterium (D), an isotope of H, was introduced into the poly-Si cap of Al2O3/HfxSi1−xO2/SiO2 high-k stacks by ion implantation. Atom probe tomography was used to image the D distribution in samples annealed under different conditions. The results clearly demonstrated that the D atoms were trapped at the interface of poly-Si and Al2O3 after annealing at 900 K for 10 min. Thus, it is possible that Al2O3 blocks the H atoms at the surface, preventing them from diffusing into the high-k dielectrics during the H2 annealing process in current fabrication technology. The current work also exhibits an example of investigating H behavior in semiconductors by atom probe tomography.

Interactions between CXCL12 and its receptors CXCR4 or CXCR7 are involved in tumor growth and metastasis in various types of human cancer. However, CXCL12 expression and its role in lung cancer are not fully elucidated. Here we examined the expression of CXCL12 in 54 lung cancer cell lines consisting of 23 small cell lung cancers (SCLCs) and 31 non-small cell lung cancers (NSCLCs). CXCL12 was overexpressed in lung cancer cell lines compared to non-malignant human bronchial epithelial cell lines (N = 6). CXCL12 expression was positively but weakly correlated with the expression of CXCR4 or CXCR7. We also examined CXCL12 expression in 89 NSCLC specimens and found that CXCL12 expression was significantly higher in tumor specimens from female patients, non-smokers and adenocarcinoma patients. Small interfering RNAs targeting CXCL12 inhibited cellular proliferation, colony formation and migration of CXCL12-overexpressing lung cancer cells; however, this inhibition did not occur in lung cancer cells that lacked CXCL12. Furthermore, the anti-CXCL12 neutralizing antibody mediated inhibitory effects in three lung cancer cell lines that overexpressed CXCL12, but not in two CXCL12 non-expressing lung cancer cell lines nor two non-malignant bronchial epithelial cell lines. The present study demonstrates that: CXCL12 is concomitantly overexpressed with CXCR4 or CXCR7 in lung cancers; CXCL12 is highly expressed in NSCLCs from females, non-smokers and adenocarcinoma patients; and disruption of CXCL12 inhibits the growth and migration of lung cancer cells. Our findings indicate that CXCL12 is required for tumor growth and provide a rationale for the anti-CXCL12 treatment strategy in lung cancer.

This study investigated the validity of a wire mesh catalyst support. The wire mesh was formed from JSE20-5USR stainless steel foil subjected to expansion processing. In a hydrogen atmosphere, an iron-aluminum intermetallic compound was deposited on the wire mesh surface using heat treatment, thereby producing fine aluminum oxide whiskers on the wire mesh surface. Subsequently, Pt and/or Pd was coated directly onto the whiskers. Structures of catalysts containing Pt and/or Pd were examined using XRD and SEM. The developed catalysts were applied to a burner that was fueled by vaporized kerosene-air mixtures. The combustion gases' chemical components were measured to evaluate the developed catalysts' activity. The same loading catalyst with Pt showed higher activity than that with Pd. Formation of either a catalyst loaded with Pt or Pt supported on a Pd layer is beneficial for reducing CO and NOx emissions in combustion gases and for maintaining stable combustion. This wire mesh catalyst is applicable for practical catalytic combustors of kerosene fuel. It presents particular advantages of good design flexibility and low pressure drop.

In order to probe the fundamental behaviors of point defects in silicon and germanium, we studied the self-diffusion using isotope superlattices. In ion-implanted germanium, vacancies are in thermal equilibrium and transient enhanced diffusion is not present under the experimental conditions employed in this study. In contrast, silicon self-interstitials are supersaturated in ion-implanted silicon and the self-interstitial concentration is going down to the thermal equilibrium value toward the surface.

For early detection of autism, it is difficult to maintain an efficient level of sensitivity and specificity based on observational data from a single screening. The Extraction and Refinement (ER) Strategy utilizes a public children's health surveillance program to produce maximum efficacy in early detection of autism. In the extraction stage, all cases at risk of childhood problems, including developmental abnormality, are identified; in the refinement stage, cases without problems are excluded, leaving only cases with conclusive diagnoses.The city of Yokohama, Japan, conducts a routine child health surveillance program for children at 18 months in which specialized public health nurses administer YACHT-18 (Young Autism and other developmental disorders CHeckup Tool), a screening instrument to identify children at risk for developmental disorders. Children who screen positive undergo further observation, and those without disorders are subsequently excluded. To study the efficacy of early detection procedures for developmental disorders, including autism, 2,814 children born in 1988, examined at 18 months of age, and not already receiving treatment for diseases or disorders were selected.In the extraction stage, 402 (14.3%) children were identified for follow-up. In the refinement stage, 19 (.7%) of these were referred to the Yokohama Rehabilitation Center and diagnosed with developmental disorders. The extraction stage produced four false negatives, bringing total diagnoses of developmental disorders to 23 (.8%) - including 5 with autistic disorder and 9 with pervasive developmental disorder - not otherwise specified (PDDNOS). Sensitivity was 60% for autistic disorder and 82.6% for developmental disorders. Specificity for developmental disorders rose to 100% with the ER Strategy. Picture cards used in YACHT-18 provided a finer screen that excluded some false positive cases.An extraction and refinement methodology utilizing child health surveillance programs achieve high efficacy for early detection of autism.

The PI3K family is thought to participate in TLR signaling, and it has been reported to be a negative regulator of TLR-mediated production of IL-12, a key inducer of Th1 responses. However, the role of individual PI3K subtypes in IL-12 production remains obscure. We defined the distinct regulation of LPS-mediated IL-12 production by p110α and p110β catalytic subunits of PI3K in human APCs. We observed that knockdown of PI3K p110β by small interfering RNA (siRNA) suppressed both LPS-induced IL-12 protein production and mRNA expression in monocyte-derived macrophages and dendritic cells (DCs). Knockdown of PI3K p110α by siRNA reduced LPS-induced IL-12 protein production in both cell types. Conversely, knockdown of PI3K p110α suppressed LPS-induced IL-12 mRNA expression in monocyte-derived macrophages but minimally affected monocyte-derived DCs. PI3K p110β siRNA inhibited JNK activation, but not p38 MAPK or ERK activation, stimulated by LPS, while PI3K p110α siRNA did not affect LPS-induced JNK, p38 MAPK, or ERK activation in both cell types. Transfection of siRNA against JNK1, JNK2, and both decreased LPS-induced IL-12 production. Furthermore, PI3K p110β siRNA attenuated LPS-induced JNK1 phosphorylation, while not affecting JNK2 phosphorylation. Our findings indicate that PI3K p110β positively controls LPS-induced IL-12 production through the JNK1-dependent pathway in human macrophages and DCs.

In urban river management, 'controlling the river flow', 'maintaining the river basin' and 'preserving the ecological environment' are the most important components. However, these are not necessarily considered at simultaneously in practical phases. Each of the components is handled individually. In this paper, a mathematical model for analyzing the relationship among the components is proposed. The relationships among elements in the components are modeled with differential equation. By analyzing the characteristics of equilibriums and their convergence paths, possible symbiotic dynamics of socio- and biospheres are considered. As one of the implications of scenario analysis, it is revealed that if local people engage in activities that improve the river environment for a purpose of relaxation, the balance of the biosphere would eventually change, which would not bring about a good symbiotic state for socio- and biospheres.

Resolvin E1 (RvE1; 5S, 12R, 18R-trihydroxyeicosapentaenoic acid) is an anti-inflammatory lipid mediator derived from the omega-3 fatty acid eicosapentaenoic acid (EPA). It has been recently shown that RvE1 is involved in the resolution of inflammation. However, it is not known whether RvE1 is involved in the resolution of asthmatic inflammation. To investigate the anti-inflammatory effect of RvE1 in asthma, a murine model of asthma was studied. After RvE1 was administered to mice intraperitoneally, there were decreases in: airway eosinophil and lymphocyte recruitment, specific Th2 cytokine, IL-13, ovalbumin-specific IgE, and airway hyperresponsiveness (AHR) to inhaled methacholine. Moreover, RvE1-treated mice had significantly lower mucus scores compared to vehicle-treated mice based on the number of goblet cells stained with periodic acid-schiff (PAS). These findings provide evidence that RvE1 is a pivotal counterregulatory signal in allergic inflammation and offer novel multi-pronged therapeutic approaches for human asthma.

In this research, a method of designing an EPS control system that achieved a good steer feeling without using an actual vehicle was examined. Firstly, evaluation functions to evaluate steer feeling theoretically were set. And it was described that steer feelings such as “inertial feeling” and “viscous feeling” could be expressed by the evaluation functions. Secondly, a target characteristic that made the steer feeling good was determined on the evaluation function, and control methods to theoretically achieve this target characteristic were described. Finally, the designed control system was installed in an EPS vehicle. As a result, it was confirmed that the steer feeling in an actual vehicle was fine with no “inertial and viscous feeling”.

Selective preparation of poly(p-oxybenzoyl) (POB) crystals was examined from the viewpoint of a dimer effect on fractional polycondensation. Four different copolymerization systems were chosen as the combinations of p-acetoxybenzoic acid (p-ABA), m-acetoxybenzoic acid (m-ABA), and their dimers. The crystals obtained from the copolymerization of the dimer of p-ABA (p-ABAD) and m-ABA contained only 3.1 mol % of m-oxybenzoyl moiety even at high content of m-oxybenzoyl moiety in feed (χf) of 40 mol %. p-Oxybenzoyl homo-oligomers were more rapidly formed from p-ABAD in the solution than from p-ABA, and they were crystallized to form the crystals with segregating co-oligomers. While co-oligomers containing more m-oxybenzoyl moiety were formed in the solution, afterward they were unable to be phase-separated because of higher miscibility. The further polycondensation proceeded in the precipitated crystal, and finally the POB crystal was selectively formed. Lower polymerization temperature and concentration enhanced the fractionability, and the POB crystals containing less than 1 mol % m-oxybenzoyl moiety were prepared at χf of 30 mol %, 270 °C, and a concentration of 0.5%. The dimer effect on the fractional polycondensation was clearly observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1598–1606, 2008