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We compared the photoluminescence (PL) properties of AlInAsSb digital alloy samples with different periods grown on GaSb (001) substrates by molecular beam epitaxy. Temperature-dependent S-shape behavior is observed and explained using a thermally activated redistribution model within a Gaussian distribution of localized states. There are two different mechanisms for the origin of the PL intensity quenching for the AlInAsSb digital alloy. The high-temperature activation energy E 1 is positively correlated with the interface thickness, whereas the low-temperature activation energy E 2 is negatively correlated with the interface thickness. A quantitative high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) study shows that the interface quality improves as the interface thickness increases. Our results confirm that E 1 comes from carrier trapping at a state in the InSb interface layer, while E 2 originates from the exciton binding energy due to the roughness of the AlAs interface layer.

The purpose of the study was to translate the athlete burnout questionnaire (ABQ) into Simplified Chinese and examine its psychometric properties in Chinese collegiate athletes and elite athletes. Firstly, the factor structure, internal consistency reliability and nomological validity of the Chinese translated ABQ was examined in a sample of Chinese collegiate athletes (n = 214, 58.9% females). Secondly, abovementioned psychometric properties were examined in a sample of Chinese elite athletes (n = 505, 52.7% females). Finally, measurement invariance of the Chinese translated ABQ was examined across the two samples. It was found that the 12-item three-correlated-factors model outperformed the one factor model and bi-factor model in collegiate athlete sample whereas the 12-item bi-factor model best represented the factor structure of the Chinese translated ABQ in elite athlete sample. Satisfactory internal consistency reliabilities of the Chinese translated ABQ were evidenced in the two samples. Nomological validity was also supported by the results of the two samples that the three subscales of the ABQ were significantly associated with its theoretically related variables. Results of multiple-group confirmatory factor analysis revealed that weak measurement invariance of the Chinese translated ABQ (three-correlated-factors model) was evidenced across the two samples. Collectively, results of this study indicated that the 12-item Chinese translated ABQ could be used for measuring burnout of Chinese collegiate and elite athletes. Significance and implication of the current study as well as recommendations for future study were discussed.

The etching and passivation processes of very long wavelength infrared (VLWIR) detector based on the InAs/GaSb/AlSb type-II superlattice have been studied. By studying the effect of each component in the citric acid solution (citric acid, phosphoric acid, hydrogen peroxide, deionized water), the best solution ratio is obtained. After comparing different passivation materials such as sulfide + SiO2, Al2O3, Si3N4 and SU8, it is found that SU8 passivation can reduce the dark current of the device to a greater degree. Combining this wet etching and SU8 passivation, the R 0 A of VLWIR detector with a mesa diameter of 500 μm is about 3.6 Ω⋅cm2 at 77 K.

The occurrence of emerging pollutants pharmaceuticals and personal care products (PPCPs) in aquatic environments has potential adverse effects on aquatic organisms, and the presence of PPCPs in drinking water sources is very likely to cause harm to human health. The PPCPs pollution in five typical drinking water sources in Henan province was investigated. Moreover, the source of pollutants was analyzed and the relevant ecological risks were evaluated. The results showed that the cumulative concentrations of 20 PPCPs at different sampling sites ranged from 24.2 to 317.6 ng·L

A comparative study of single- and co-substitution of Ti on dehydrogenation of Mg2NiH4 has been carried out from first-principles calculations based on density functional theory. In comparison with Ti single-substitution, the formation enthalpy in co-substituted Mg2NiH4 is higher, showing the lower thermodynamic stability. In Ti co-doped Mg2NiH4, the average Ni H bond length of entire unit cell is larger, implying weaker Ni H bonds and lower stability of complexes NiH44−. Ti co-substitution further shows a more favorable dehydrogenation effect on Mg2NiH4 due to lower hydrogen dehydrogenation energy, and significantly reduces the dehydrogenation reaction enthalpy of Mg2NiH4 by about 30% compared to the pure state. Further calculated electronic structure demonstrates that the co-substituted Mg2NiH4 displays a metallic behavior with the Fermi level locating at the doping band, and the underlying mechanism for improving dehydrogenation properties of co-substituted Mg2NiH4 can be attributed to the weakened Ni H interactions together with the narrowed energy gap.

The structural evolution and electronic mechanism for KBH 4 phase transition have been systematically investigated using first-principles calculations. The present results demonstrate experimentally observed stability order of α-KBH 4 > β-KBH 4 > γ-KBH 4 , and the predicted transition pressure at 0 K for cubic → tetragonal → orthorhombic phase transformation agrees reasonably with experimental measure. The atomic process indicates that KBH 4 structural evolution is closely related to rotation and deformation of [BH 4 ] − clusters as well as shift of [BH 4 ] − clusters and K atoms. Along with phase transformation, the band gap of KBH 4 narrows, the B H covalent bond weakens while K H interaction enhances, the K K anti-bonding and coulomb repulsion are also stronger.

The crystal structure of LiCa(AlH4)3 was investigated via first principle calculations, especially the positions of hydrogen atoms undetected in XRD experiments were predicted, then the thermodynamic favourability of the experimentally reported structure with respect to several candidates from the inorganic crystal structure database (ICSD) was confirmed. It is found that hexagonal packing of AlH4 layers along the c axis is present in LiCa(AlH4)3, and the detailed geometrical feature is further revealed. The electronic structures show that in LiCa(AlH4)3 the Li–AlH4 interaction is more covalent than in LiAlH4, while the Ca–AlH4 covalence is less than in Ca(AlH4)2. The overall stronger covalence in LiCa(AlH4)3 leads to weakened Al–H bonds. The Li–H interaction in LiCa(AlH4)3 dramatically turns out to be strong bonding, opposite to the Li–H anti-bonding in LiAlH4. The Ca–H bonds are more anti-bonding in LiCa(AlH4)3.

The Cu-doping effects on dehydrogenation of MgH2 (001) and (110) surfaces were investigated by using first-principles calculations. On the basis of the calculation results of total energy, the Cu dopant prefers to occupy the interstitial site on both surfaces rather than substitute a Mg atom, and the Cu dopant bonds with four adjacent H ions to form a CuH4 cluster. The electronic structures show that Cu–Mg and Cu–H interactions strongly weaken Mg–H interactions, which leads to a reasonable expectation of decreased dehydrogenation temperature. The kinetic barriers for Cu-doped (001) and (110) surfaces are, respectively, reduced to 1.83 and 1.48 eV, showing that improved kinetics can be expected due to the much lower desorption barriers on both Cu-doped surfaces. The present results are beneficial to resolve the disputes between previous reports on the catalytic effects of Cu-doping in the MgH2 system.

Theoretical study of structural stability and elastic properties of α - and β -MgPd 3 intermetallic compounds as well as their hydrides have been carried out based on density functional theory. The results indicate α -MgPd 3 is more stable than β phase with increased stability in their hydrides. The calculated elastic constants of α -MgPd 3 are overall larger than β phase. After hydrogenation, the elastic constants are enlarged. And the elastic moduli exhibit similar tendency. The anisotropy of α -MgPd 3 is larger than β phase, and the hydrides demonstrate larger anisotropy. Their ductility follows the order of α -MgPd 3 H 0.5 α -MgPd 3 β -MgPd 3 H β -MgPd 3 . Compared with β phase, higher Debye temperature of α -MgPd 3 implies stronger covalent interaction, and the Debye temperature of hydrides increases slightly. The electronic structures demonstrate that the Pd–Pd interaction is stronger than Pd–Mg, and Pd–H bonds play a significant role in the phase stability and elastic properties of hydrides.

First-principles calculations based on density functional theory (DFT) were performed to study the destabilizing mechanism of co-doped MgH 2 with Al and Y. From the minimization of total electronic energy, the preferential positions of dopants are determined. The calculated formation enthalpy and substitution enthalpy show that incorporation of Al combined with Y atoms into MgH 2 is energetically favorable relative to Al doping alone. Due to strong interaction of the dopant Y with Mg and Al, the hydrogen dissociation energy and the dehydrogenation enthalpy are both reduced, indicating that the synergetic effect of Al and Y on destabilizing the MgH 2 is superior to that of Al doping. The electronic structures show that the breakage of Mg–H bond is much easier in co-doped case, because of the conduction band shift below the Fermi level and the hybridization of dopants with Mg atoms, which effectively decrease the hybridization between Mg and H.

Based on the synchroshear model, the formation of stacking fault and twinning fault in C15 Laves phases is modeled, then the generalized stacking fault energy curves and deformation mechanism in C15 Laves phases Cr2X (X = Nb, Zr, Hf) alloys are investigated by ab initio calculations based on the density functional theory. The results demonstrate that the unstable stacking fault and twinning fault energies of C15 Laves phases Cr2X (X = Nb, Zr, Hf) by the synchroshear are still large while the stable stacking fault and twinning fault energies are low, and the deformation modes by extended partial dislocation and twining are feasible in C15 Laves phases Cr2X (X = Nb, Zr, Hf). Moreover, the Cr2Nb has the largest deformation twinning tendency, followed by Cr2Zr and Cr2Hf. The evolution of electronic structure during the synchroshear process is further studied to unveil the intrinsic mechanism for the formation of stacking fault and twinning fault in C15 Laves phases Cr2X (X = Nb, Zr, Hf).

The crystal and electronic structure of the title compound is investigated by first principle DFT calculations.

Aim: To report the efficacy and safety of infliximab in the treatment of active rheumatoid arthritis (RA) in Chinese patients. Methods: This is a multicentre double-blind placebo controlled study. Patients with active RA despite being on a stable dose of methotrexate were randomly assigned to receive either infliximab 3 mg/kg body weight or placebo infusion at weeks 0, 2, 6 and 14. All patients continued their stable dose of methotrexate throughout the study. Patients were assessed at weeks 0, 2, 6, 14 and 18 for the American College of Rheumatology (ACR) 20%, 50% and 70% response (ACR20, 50 and 70, respectively). Health assessment questionnaire (HAQ), erythrocyte sedimentation rate (ESR), c-reactive protein (CRP), duration of morning stiffness and adverse effects were monitored. Results: Infliximab was effective in improving the disease activity of RA with significant ACR20 response observed at week 2 (infliximab vs. placebo 52.87% vs. 13.95%, P < 0.05). Significant differences in the ACR20 and ACR50 response rates between the two treatment groups were also observed at week 18 (75.86% and 43.68% of patients receiving infliximab vs. 48.84% and 25.58% and 13.95% of patients on placebo, P = 0.0003 and P = 0.011, respectively). Infliximab was generally well tolerated. The rate of adverse events and withdrawal due to adverse events were similar between the two groups. Most adverse reactions were transient. One patient in the infliximab group developed tuberculosis during the study. One patient in the placebo group developed antinuclear antibodies without obvious signs of systemic lupus erythematosus. Conclusion: In this preliminary study, infliximab infusions, at a dose of 3 mg/kg body weight given at various intervals over 14 weeks, were effective in controlling the signs and symptoms of active RA in Chinese. Infliximab also appeared to be well tolerated. Further studies involving a larger number of patients over a more prolonged period will further evaluate the long-term efficacy and safety of infliximab in this group of patients.

Aim: To evaluate the efficacy and safety of diacerein in patients with knee osteoarthritis (OA). Methods: A total of 223 patients fulfilling the American College of Rheumatology criteria for knee OA were enrolled in this 17-week, randomized, double-dummy, diclofenac-controlled trial, with diacerein dosages of 100 mg/day and diclofenac sodium administered at 75 mg/day. Result: After 12 weeks of treatment, the total efficacy rates of patient/physician global assessment in diacerein and diclofenac groups were 65.4%/61.6% and 61.2%/61.2% respectively (P > 0.05). In the intent-to-treat population, the primary criterion (visual analogue scale [VAS] assessment of pain on walking 20 m) was significantly superior (P 0.05). Mild-to-moderate gastrointestinal disorders were the most frequent adverse events. Conclusion: Diacerein was shown to be as effective as diclofenac sodium in treating patients with knee OA, coupled with a carry-over effect. Diacerein was generally well tolerated, with a good safety profile. No severe adverse events were occurred.

Network course provides a new form in developing new teaching resources and extending classroom teaching, offers a positive and practical significance in optimizing the quality of teaching and transmitting education information. The modular design of Physical Education (P.E.) network course constitutes an integrated teaching system, which includes an overall plan on teaching system, special module development, and systematic integration of teaching topics, teaching system evaluation and testing. It will fully integrate the content of different areas of expertise to improve the scientificity, relevance and effectiveness of teaching. The P.E. program which was developed based on the internet framework software platform has the functions of course management, curriculum development and course research. Through one semester teaching experiment, the results of final exam and fitness tests indicated that the network course assisting P.E. teaching got better performance than traditional teaching.

Acute gout is an intensely painful, inflammatory arthritis. Although the non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for this condition, the efficacy is based on only a few studies, particularly in China. We tried to assess the safety and efficacy of etoricoxib in the treatment of acute gouty arthritis in China.A randomized, double-blind, active comparator study was conducted at 10 sites in China. Patients (n = 178; ≥ 18 years of age) with acute gouty attack (48 hours) were treated for 5 days with etoricoxib (120 mg/d; n = 89) or indometacin (75 mg twice daily; n = 89). The primary efficacy end point was self-assessed pain in the affected joint (0-4 point Likert scale) from days 2 - 5. Secondary end points included investigator assessments of tenderness and swelling, patient/ investigator global assessments of response to therapy, and patients discontinuing treatment. Safety was assessed by adverse events (AEs).Etoricoxib and indometacin had comparable primary and secondary end points. Mean change difference from baseline from days 2 - 5 was 0.03 (95% confidence interval (CI) -0.19 to 0.25; P = 0.6364), which fell within the prespecified comparative bounds of -0.5 to 0.5. No severe AEs were associated with etoricoxib use. Non-severe AEs were mainly digestive and general, and most (73.7%) were mild, although they caused withdrawal of two subjects in the etoricoxib group, due to bilateral renal calculi and uronephrosis of the left kidney (unrelated to etoricoxib) and fever and chills (potentially etoricoxib-related). Overall, AEs were similar, although the absolute number of AEs in the etoricoxib group (n = 31) was less than the indometacin group (n = 34).Etoricoxib (120 mg once daily) is effective in treating acute gout, is generally safe and well-tolerated, and is comparable in efficacy to indometacin (75 mg twice daily).

To evaluate the efficacy and safety of hydroxychloroquine (HCQ) in pregnant patients with systemic lupus erythematosus (SLE).Twenty-four pregnant patients with SLE treated with HCQ during pregnancy from May, 2006 to February, 2011 were studied retrospectively. All babies were followed up during early infancy for growth development.Of them, 22 patients were treated with HCQ throughout the whole pregnancy with no lupus flare occurred in 21 patients (95.4%), while temporary discontinuation of HCQ precipitated a flare of disease in two patients. Three patients (12.5%) had premature delivery, and pregnancy induced hypertension happened in 3 patients (12.5%). No congenital abnormalities occurred and mean follow-up of 26 months (range 1 - 47 months) revealed no abnormalities in these children.Our findings reinforce the safety of HCQ therapy during pregancy and HCQ should probably be maintained throughout the pregancy in patients with SLE.

To study the levels of cartilage oligomeric matrix protein (COMP) and matrix metalloproteinase-3 (MMP-3) in the serum fluid of osteoarthritic rabbit models and their relationships with the severity of pathological changes, so as to investigate their correlation with osteoarthritis (OA).The osteoarthritic animal models were get from immobilizing the right knees of 18 rabbits in full extension using plaster cast. Knee joint pathological changes of 2, 6 weeks were examined for pathological severity of OA; ELISA sandwich method was used to measure the levels of COMP and MMP-3 in serum before and after modeling (at 2, 6 weeks respectively); X ray of model keens was also obtained in different period. Correlation analysis was performed to demonstrate the relationship between the levels of COMP, MMP-3 in the serum and the pathological severity of OA.(1) Morphological observations:immobilizing the right knees of rabbits in full extension using plaster cast was a reliable method for osteoarthritic animal models and the typical histopathologic character was seen; the severity of osteoarthritis gradually increased with time extended. (2) The levels of COMP [(3.64 ± 0.18) µg/L], MMP-3 [(1.99 ± 0.81) µg/L] in the serum of 2 weeks osteoarthritic animal models were higher than those before immobilizing with plaster cast [COMP (3.35 ± 0.20) µg/L, MMP-3 (1.61 ± 0.71) µg/L]. The levels of COMP [(3.96 ± 0.44) µg/L], MMP-3 [(3.44 ± 0.91) µg/L] of 6 weeks were much higher, with a significant difference (P0.05). The levels of COMP, MMP-3 in serum had a linear correlation with the pathological severity of OA (r0.710, and P0.05).The levels of COMP and MMP-3 in serum can help to predict and evaluate the progression of OA.

To evaluate the short-term efficacy and safety of etanercept treatment in Chinese patients with active ankylosing spondylitis (AS).This was a 12-week multicenter, double-blind, placebo-controlled, randomized phase III clinical study. The first part was a 6-week placebo-controlled period followed by a 6-week open-label period. The primary efficacy endpoint was the percentage of subjects achieving a 20% improvement in assessment in ankylosing spondylitis (ASAS) (ASAS 20). The secondary efficacy endpoints were the percentage of patients achieving a 40% improvement in ASAS (ASAS 40), achieving a 50% improvement in ASAS (ASAS 50), achieving a 70% improvement in ASAS (ASAS 70), and ASAS 5/6 responses at all visits, and the improvement in subject global assessment, physician global assessment, nocturnal and total back pain, bath AS functional index (BASFI), bath AS disease activity index (BASDAI), spinal mobility, joint assessment and quality of life assessment. All subjects in the study were evaluated for safety.The primary endpoint, ASAS 20 at week 6, was achieved by 86.5% (64/74) patients in the etanercept group compared to 29.5% (23/78) patients in the placebo group (P0.001). As early as week 2, the percentages of patients achieving the ASAS 20 between the two groups were significantly different. Furthermore, the majority of secondary efficacy end points were also significantly improved. Most of adverse events (AE) were mild in nature, the commonest adverse events were elevated liver function levels, injection site reactions and nasopharyngitis. No death or serious AE were observed.Etanercept can improve symptoms fastly, significantly and safely in Chinese patients with active AS.

To investigate the efficacy and safety of adalimumab plus methotrexate (MTX) for the treatment of rheumatoid arthritis (RA).This is a multi-center, randomized, double-blind, parallel-group, and placebo-controlled clinical study, included a total of 302 cases of active rheumatoid arthritis, randomized into three groups of observation: 40 mg adalimumab (121 cases), 80 mg adalimumab (121 cases), or placebo (60 cases). Upon enrollment, all subjects had been previously treated with MTX for at least 3 months, and their doses of drug had remained stable for at least 28 days. The double-blind phase lasted for 12 weeks, during which the subjects were administered with adalimumab or placebo subcutaneously every other week. Then the subjects entered into another 12 weeks of open-label study, which included subcutaneous injection of 40 mg adalimumab every other week. In both the double-blind and the open-label periods, all subjects were maintained concomitantly with MTX that had already been used before this study. The primary efficacy variables were evaluated on basis of American College of Rheumatology (ACR)20 response rate at week 12. The secondary efficacy variables included: ACR20 response rate at week 24; ACR50 and ACR70 response rates at weeks 12 and 24; and changes at weeks 12 and 24 compared with baseline observations for tender and swollen joint counts, as well as the assessment of pain with visual analog scale (VAS), the physician's and the patient's global assessment of disease activity (VAS), and the analysis on health assessment questionnaire (HAQ) and health related quality of life (HRQL) measured by Short Form-36 (SF-36); The safety variables mainly included adverse events (AE).During the double-blind period, subjects treated with 40 mg of adalimumab, 57.0% achieved ACR20 response at week 12 (P = 0.004 versus placebo), and subjects treated with 80 mg of adalimumab, 51.2% achieved ACR20 response at week 12 (P = 0.026 versus placebo), and only 35.0% of subjects treated with placebo achieved ACR20 response at week 12. On the other hand, 32.2% of subjects receiving 40 mg of adalimumab achieved ACR50 response (P = 0.009 versus placebo), and 15.7% achieved ACR70 response (P = 0.007 versus placebo) at week 12. Subjects treated with 40 mg of adalimumab got a better result versus placebo at week 12 for tender joint count, swollen joint count, and improvement in C-reactive protein; and subjects treated with 80 mg of adalimumab were also seen an amelioration versus placebo at week 12 for swollen joint count, and improvement in C-reactive protein; all of these findings were statistically significant in differences. During the open-label period all subjects received 40 mg of adalimumab, and response rates for ACR20, ACR50, and ACR70 in the two treatment groups of 40 mg and 80 mg adalimumab were maintained or improved from week 12 to week 24 (being 73.1%, 40.3% and 17.6% respectively for 40 mg group; 71.1%, 39.5% and 17.5% respectively for 80 mg group); while response in the original placebo group (being 67.8%, 44.1% and 18.6%) increased during the 12-week open-label period to match that of the original adalimumab treatment groups. While for changes in tender and swollen joint counts, VAS, HAQ, SF-36, a significant improvement was seen at week 24 when compared with baseline and week 12 values. Throughout the double-blind and open-label period, adverse events reported in/= 5% of subjects at least possibly associated with the study drug were upper respiratory tract infection, nasopharyngitis, and injection site itching, mostly being mild to moderate in severity. There were 3 cases of tuberculosis reported during this study. And 3 cases of serious adverse event (SAE) were reported among the adalimumab subjects during the double-blind period, which were determined as unrelated or probably unrelated to the study drug. And 8 cases (2.7%) of SAE were seen among the adalimumab subjects during the open-label period, 3 of which were at least possibly unrelated with the study drug. All SAEs reported were consistent to those seen in other adalimumab trials. No other unexpected safety signals were reported.Adalimumab plus MTX is better than single MTX in efficacy for the treatment of RA. Being generally safe and well tolerated, adalimumab plus MTX can significantly increase the response rate, continuously reduce the arthritic signs, symptoms and the inflammatory factors in patients, and also be helpful for reducing disabilities and improving the global quality of life for the patients.

To investigate the efficacy and safety of Infliximab (IFX) plus methotrexate (MTX) combination therapy in patients with rheumatoid arthritis (RA).Prospectively observe refractory RA patients who were treated with combination therapy of MTX and IFX. IFX was infused at the dosage of 3 mg/kg, in week 0, 2, 6, and then every 8 weeks. During treatment, clinical variables, disease activity and adverse effects were evaluated.After treatment, 69.8%, 52.4%, 29.5% and 7.2% RA patients achieved ACR20, ACR50, ACR70 and ACR90 respectively. There were significant statistical differences in the changes of swollen joint counts, tender joint counts, VAS scale, patient' s global assessment, and physician's global assessment before and after therapy.Infliximab plus MTX achieved significant efficacy and safety in refractory RA patients.

To evaluate the efficacy and safety of diacerein in patients with knee osteoarthritis (OA).A total of 223 patients satisfying the American College of Rheumatology criteria for knee OA were chosen for this 17-week, randomized, double-dummy, diclofenac sodium-controlled trial, with diacerein dosage of 100 mg/d and diclofenac sodium of 75mg/d. Efficacy and safety of both drugs were evaluated.Totally 106 patients in the diacerein group and 107 patients in the diclofenac group were considered qualified for the evaluation. After 12 weeks of treatment, the total effective rates of patients/physicians' overall assessment in diacerein and diclofenac groups were 65.4%/61.6% and 61.2%/61.2%, respectively (P0.05). The primary efficacy parameter [visual analog scale (VAS) assessment of pain on 20 metres walking] and the secondary efficacy parameters [tenderness on palpation, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and 36-item Short-Form (SF-36) Health Survey] significantly improved compared with baseline in both groups (P0.05). In the follow-up period, there were no obvious changes in above parameters in diacerein group. However, in diclofenac group, pain on 20 metres walking, tenderness on palpation, and WOMAC became aggravated after withdrawing the drug for 4 weeks (P0.05). Moreover, the consumption of paracetamol was significantly lower in diacerein group than in diclofenac group during follow-up (P0. 001). The incidences of related adverse events were 35.7% in diacerein and 45.1% in diclofenac group, respectively. Mild-to-moderate gastrointestinal disorders were the most frequent adverse events.Diacerein is as effective as diclofenac sodium in treating patients with knee OA. Furthermore, it has better extended effect and a good safety profile. It is generally well tolerated and has no severe adverse effect.

Proteasome, a high molecular weight multicatalytic protease complex,is responsible for most non-lysosomal intracellular protein degradations. The proteasome is composed of a 20 S catalytic core (20 S proteasome) and additional subunits, that are thought to be involved in the recognition of proteins or in the regulation of the protease activity of the proteasome. A 180 kD activator, named PA28 or Reg, associates with the 20 S proteasome and enhance the peptidase activity of the 20 S core enzyme. In this report, the biochemical isolation of the PA28-associated proteasome subset from the 20 S proteasome core is described, based on gradient anion exchange chromatography. The PA28-20 S proteasome subset, isolated from EBV-transformed B cells, was found to be highly enriched in the LMP2 (low molecular weight protein) subset, whereas no LMP2 was detected by immunoblotting in the PA28-20 S proteasome subset. The close correlation of expression of PA28 and LMP2, two interferon (IFN)-gamma inducible proteasome components,on a single proteasome subset suggests that PA28 may associate preferentially with LMP2-containing proteasomes, and/or this subset may have a specific role in the processing of environmental antigens.