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Purpose: Metastasis-directed therapy (MDT) is increasingly used in castration-sensitive oligometastatic prostate cancer because it prolongs progression-free survival (PFS) and androgen deprivation free survival. Here we describe patterns of recurrence and identify modes of progression after MDT using SABR. Methods and Materials: Two hundred fifty-eight patients with castration-sensitive oligometastatic prostate cancer (≤5 lesions at staging) were retrospectively identified from a multi-institutional database. Descriptive patterns of recurrence and modes of progression were reported. Other outcomes including median time to prostate-specific antigen (PSA) recurrence, time to next intervention, distant metastasis–free survival, overall survival, and biochemical PFS (bPFS) were reported. Survival analysis was performed using the Kaplan-Meier method, and multivariable analysis was performed. Results: Median follow-up was 25.2 months, and 50.4% of patients received concurrent androgen deprivation. Median time to PSA recurrence was 15.7 months, time to next intervention was 28.6 months, distant metastasis–free survival was 19.1 months, and bPFS was 16.1 months. Two-year overall survival was 96.8%. On multivariable analysis, factors associated with bPFS included age (hazard ratio [HR], 1.03; P = .04), N1 disease at diagnosis (HR, 2.00; P = .02), M1 disease at diagnosis (HR, 0.44; P = .01), initial PSA at diagnosis (HR, 1.002; P = 3 lesions]) occurring in 23.1% of patients. Conclusions: After MDT, the majority of patients have long-term control or oligoprogression (class I or II). Recurrence tended to occur in osseous sites. These findings, if validated, have implications for future integration of MDT and clinical trial design.

PURPOSE Radiation therapy (RT) plays an important role in locoregional tumor control for anaplastic thyroid cancer (ATC). Due to its rarity, RT guidelines for ATC are lacking. We describe ATC patterns of nodal disease at presentation and progression and propose corresponding RT target volumes. METHODS AND MATERIALS We identified all patients with ATC treated at our institution with definitive or adjuvant intensity modulated radiation therapy and concomitant chemotherapy from 2006 to 2020. We identified in-field, marginal, and out-of-field sites of locoregional recurrence and progression (LRR). RESULTS Forty-seven patients met inclusion. Median follow-up was 6.6 months (interquartile range, 1.9-19.6). Nodal levels involved at presentation included: IB (2.1%), II (23.4%), III (21.3%), IV (21.3%), V (12.8%), VI (34%), and mediastinal (6.4%). All patients received elective nodal RT to levels II-IV and VI. RT volumes also included: IA (23.4%), IB (44.7%), V (87.2%), retropharyngeal/retrostyloid (RP/RS) (27.7%), and mediastinal 1 to 6 (53.2%). Cumulative incidence of LRR at 3- and 12-months was 26.1% (95% confidence interval, 15.9-42.8) and 35.7% (23.9-53.4). Isolated LRR risk at 3- and 12-months was 6.5% (2.2-19.8) and 8.9% (3.4-22.9). Fourteen (29.8%) patients experienced in-field LRR in the thyroid gland or postoperative tumor bed, II-IV, VI, and mediastinal 1 and 3A. Four (8.5%) patients had marginal LRRs, 3 of whom progressed in the mediastinum at 2, 3P, 4, and 6. Two (4.3%) patients experienced out-of-field LRRs. Throughout the pretreatment and follow-up period, no patients had disease at IA, and 1 (2.1%) patient each had disease at IB and RP/RS. No baseline or treatment characteristics, including RT dose (stratified by < or ≥66 Gy), were significant predictors of LRR on univariate analysis. CONCLUSIONS Isolated LRR risk in patients with ATC treated with comprehensive RT and chemotherapy is low. Aggressive multimodality therapy should be reserved for willing, fit patients with no or limited distant disease burden. When treating comprehensively, complete inclusion of mediastinal levels 1 to 6 may be warranted to avoid marginal disease progression. Omission of levels I and RP/RS can be considered.

PURPOSE/OBJECTIVE(S) Radiotherapy is a standard palliative treatment for spine metastasis, but pain flares (PF) are a common acute toxicity. Prophylactic corticosteroids can reduce the rate of PF in patients receiving traditional palliative regimens, but less is known about prophylaxis for stereotactic body radiotherapy (SBRT). We aim to identify a subset of patients treated with spine SBRT with the highest rate of PF to optimize the use of prophylactic steroids. MATERIALS/METHODS From December 2007-August 2019, 469 patients received 680 spine SBRT treatments. After exclusion of benign histology, particle therapy, and patients with missing data, the final cohort included 424 patients with 610 treatments. We defined PF as acute worsening of pain at the treatment site requiring initiation of or higher-dose corticosteroids, opiates, and/or hospitalization. First, data was split into 70% training and 30% validation sets with comparable patient characteristics using a random number generator. Feature importance testing was conducted, and a correlation heatmap helped exclude correlated variables. Feature extraction involved selecting the variables used in the highest-fidelity recursive partitioning analysis (RPA) models. Each RPA model was trained, validated, and tested using only the training dataset. Selected variables were verified using the Fisher exact test and univariate t-test. RESULTS We identified 125 total PF (20%), treated with steroids (14%), opioids (40%), both (39%), or hospitalization (6%). Six variables were identified by RPA. Of these, 5 met significance on Fisher exact test with P 0 (OR 2.17), SINS > 6 (OR 2.98), and gross tumor volume > 8 cc (OR 2.80). One point was assigned for each variable. The low-risk (LR) group (score = 0, n = 159) had PF rates of 7.0% and 13.6% in the training and validation sets, respectively; the intermediate-risk (IR) group (score = 1, n = 150) had rates of 14.0% and 16.3%; and the high-risk (HR) group (score > 1, n = 301) had rates of 28.8% and 31.3%. A logistic model confirmed the increased pain flare rate in the HR group compared to LR and IR treatments combined (OR = 3.50, 95% CI: 2.06-5.92) or considered separately (OR = 5.41, 2.48-11.78). The concordance index was 0.66 (0.60-0.73) and 0.62 (0.52-0.71) in the training and internal validation sets. Notably, patients with PF after prior spine SBRT had a 61% rate of PF with subsequent spine SBRT, compared to only 5% for patients without PF after prior spine SBRT. CONCLUSION Our internally-validated model identifies a high-risk group of patients more likely to develop PF after spine SBRT, for whom prophylactic steroids may confer the greatest benefit. Evaluation in a clinical trial is warranted.

Purpose/Objective(s) Radiotherapy (RT) plays an important role in locoregional control for anaplastic thyroid cancer (ATC). Due to its rarity, RT guidelines for ATC are lacking. In this single institution retrospective analysis, we describe ATC patterns of nodal disease at presentation, recurrence, and progression and propose corresponding RT target volumes. Materials/Methods We used a prospectively maintained database to identify all ATC patients with definitive or adjuvant IMRT and chemotherapy from 2006 to 2020. Patients receiving palliative RT were excluded. We identified in-field, marginal (within the 40-50 Gy isodose line), and out-of-field sites of locoregional recurrence and progression (LRR). Sites of disease at presentation and LRR were mapped to inform RT target volume recommendations. Results Forty-seven patients met inclusion. Median follow-up was 6.6 months (IQR: 1.9-19.6). Forty-four (93.6%) patients underwent resection. Table 1 summarizes RT nodal coverage and sites of disease. All patients received elective nodal RT to levels II-IV and VI. RT volumes also included: IA (23.4%), IB (44.7%), V (87.2%), VII (27.7%), and mediastinal 1-6 (53.2%). Cumulative incidence of LRR at 3- and 12-months was 26.1% (95% CI: 15.9-42.8) and 35.7% (23.9-53.4). Isolated LRR risk at 3- and 12-months was 6.5% (2.2-19.8) and 8.9% (3.4-22.9). Fourteen (29.8%) in-field LRRs occurred at a median interval of 44 days (range: 15-208) from completion of RT. Sites of in-field LRR included the postoperative thyroid bed, ipsilateral III-IV, VI, 1, and 3A. Four (8.5%) patients experienced marginal LRRs at a median of 35 days (range: 32-139), 3 of whom progressed in the mediastinum at 2, 3P, 4, and 6. Two (4.3%) patients experienced out-of-field LRRs at VII and the contralateral retromolar trigone, respectively. Throughout the pre-treatment and follow-up period, no patients had disease at IA and 1 (2.1%) patient each had disease at IB and VII. Five (10.6%) patients had bilateral neck disease. No baseline or treatment characteristics, including RT dose (stratified by Conclusion Isolated LRR risk in ATC patients treated with comprehensive RT and chemotherapy is low. Complete inclusion of mediastinal levels 1-6 is warranted to avoid marginal failures. Distant recurrence remains common and additional efforts are needed to appropriately select patients for comprehensive treatment. No dose-response relationship was observed between 51 and 70 Gy.

To identify factors predictive of locoregional recurrence (LRR) in upper tract urothelial carcinoma (UTUC) treated with nephroureterectomy and to propose adjuvant radiation therapy (ART) fields.Clinical and pathologic variables for patients receiving nephroureterectomy for UTUC between 1995 and 2009 were analyzed for associations with outcomes. Sites of LRR from all patients with available imaging (39) were contoured on computed tomography image sets of patients with representative anatomy, and ART fields were proposed based on these distributions.A total of 279 patients with a median follow-up of 13.0 years were analyzed. The 5-year cumulative incidence of LRR was 16.7% (95% CI, 12.2-21). Pathologic risk factors (PRFs) associated with increased risk of LRR included tumor in both the renal pelvis and ureter, T stage ≥2, lymph node involvement, grade 3 histology, and positive surgical margins (P.05). Patients with an increased number of PRFs had a significantly greater risk of LRR. The 5-year cumulative incidence estimates of LRR were 5.3% (95% CI, 1.8%-16.0%), 15.6% (95% CI, 9.5%-25.7%), and 43.9% (95% CI, 31.1%-62.1%) for those with 1, 2, and ≥3 PRFs, respectively. ART fields covering the renal fossa and retroperitoneal lymph nodes from the superior border of L1 through the aortic bifurcation would encompass all sites of LRR for 33 of 46 patients (72%). Non-LRR bladder and distant failure occurred in 101 (36.2%) and 73 (26.2%) of the patients, respectively. The 5-year cumulative incidence estimate of distant failure was 22.5% (95% CI, 17.4%-27.3%).In patients receiving nephroureterectomy for UTUC, LRR is significantly increased in patients with 2 or more PRFs. These data provide clinically valuable insight into the selection of candidates for ART and the design of ART fields.

PURPOSE Vertebral compression fracture (VCF) is a potential adverse effect following stereotactic body radiation therapy (SBRT) for spinal metastases. In this analysis, we developed and internally validated a risk stratification model for VCF. METHODS From an initial set of 680 treatments, we excluded those with proton therapy, prior surgical intervention, or missing data. The final dataset had 464 treatments in 313 patients. Delineations of VCF and all radiographic components of the spinal instability neoplastic score (SINS) were determined by a radiologist. Recursive partitioning analysis (RPA) was conducted using separate training (70%), internal validation (15%), and test (15%) sets. The log-rank test was used as the criterion for node splitting. RESULTS With a median follow-up of 21 months, we identified 84 VCF (18%), including 65 (77%) de novo and 19 (23%) progressive fractures. There was a median 9 months (IQR: 3 – 21) to VCF. From an initial set of 15 candidate variables, six were identified using the backwards selection method, feature importance testing, and a correlation heatmap. Four were then selected in the highest-fidelity RPA models: epidural tumor extension, lumbar location, gross tumor volume > 10 cc, and SINS > 6. One point was assigned to each variable, and the resulting multivariate Cox model had a concordance of 0.760. Each one point increase in score was associated with increasing rates of VCF. Low-risk lesions (score: 0-1, n=273) had 2-year freedom from VCF of 92%, compared to 80% for intermediate-risk (score: 2, n=99) and 56% (score: 3-4, n=92) for high-risk lesions (p < 0.0001). Cumulative incidence curves with death as a competing risk showed increased VCF with higher scores via Gray’s test (p < 0.001). CONCLUSIONS Our internally-validated model identifies a subgroup of patients with high risk for VCF who may benefit from prophylactic surgical stabilization or vertebroplasty.

Background Available therapies for castrate-resistant prostate cancer (CRPC) confer minimal survival advantage; thus, there is interest in metastasis-directed therapy (MDT) for oligometastatic or oligoprogressive disease to improve outcomes. Here, we describe outcomes of oligoprogressive CRPC treated with stereotactic ablative radiotherapy (SABR). Objective To report outcomes of oligoprogressive CRPC treated with MDT using SABR. Design, setting, and participants Patients with oligoprogressive CRPC were retrospectively evaluated, and outcomes following MDT were reported. Outcomes were additionally compared with oligoprogressive CRPC treated with change in systemic therapy alone. Intervention SABR to oligoprogressive lesions. Outcome measurements and statistical analysis Outcomes of interest were time to prostate-specific antigen (PSA) failure, time to next intervention (TTNI), distant metastasis-free survival (DMFS), and overall survival. Survival analysis was performed using the Kaplan-Meier method, and univariable analysis and multivariable analysis (MVA) were performed. Results and limitations A total of 68 patients were included. After MDT, median time to PSA recurrence, TTNI, and DMFS were 9.7, 15.6, and 10.8 months, respectively. A total of 112 lesions were treated, and the cumulative incidences of local failure at 12 and 24 months were 2.1% and 13.8%, respectively. Factors associated with the risk of local recurrence on univariable analysis were age (hazard ratio [HR] 1.07, p = 0.03) and Gleason grade group (HR 2.20, p = 0.07). Compared with change in systemic therapy alone (n = 52), MDT (n = 31) was associated with improved median time to PSA failure (9.7 vs 4.2 months, p = 0.066)), TTNI (14.9 vs 8.8 months, p = 0.025), and DMFS (12.7 vs 8.9 months, p = 0.045), and remained associated with improved outcomes on MVA. Conclusions In a retrospective cohort of oligoprogressive CRPC patients, MDT was associated with favorable outcomes and improved cancer control as compared with change in systemic treatment alone. Future prospective trials are needed to confirm these findings. Patient summary In this report, we retrospectively analyzed outcomes of patients with oligoprogressive castrate-resistant prostate cancer treated with radiation therapy to progressing lesions. Our results suggest that treatment of these lesions with radiation therapy can result in sustained periods of disease-free survival and might add benefit in addition to systemic therapy at the time of progression. These results need to be verified in a prospective trial to identify the optimal integration of radiation therapy into metastatic castrate-resistant prostate cancer.

e20554 Background: The paradigm for locally advanced non-small cell lung cancer has been markedly altered to include maintenance durvalumab (D) post completion of definitive chemoradiation (CRT) following the publication of the Pacific trial in 2018. The toxicity of this treatment has not been well evaluated in the real-world setting. Methods: We identified 42 patients (pts) with Stage IIB-IIIC NSCLC treated at Mayo Clinic Rochester between 6/1/2018 and 10/1/2020 who received definitive CRT followed by maintenance D. Data were abstracted by retrospective chart review under an IRB approved protocol. Results: Median age was 66 yrs (range 47-90) and 62% were women. Primary lung cancer histology included 19 adenocarcinoma, 20 squamous cell, and 3 adenosquamous. The distribution of stages was: IIB (4/42), IIIA (15/42), IIIB (19/42), IIIC (4/42). Approximately half of patients had PDL1 expression > 25% (20/42). With a median follow up of 12.2 months (calculated from first cycle of D; range 4.2-30.5 months), 14 had completed one year of maintenance D, 16 were receiving ongoing D, and 10 stopped D early with 6/12 discontinuing due to disease progression (4/6 local progression, 2/6 distant progression). Other reasons for discontinuation (5/10) included grade 3 colitis, grade 2 hepatitis, aspergillus lung infection, and flare of autoimmune disorders. One quarter of patients experienced grade 2 radiation pneumonitis (RP; 10/42) with median time to development of RP 78 days from end of CRT and 45 days from start of D. RP was determined by multidisciplinary review of imaging and treatment fields. 17/42 patients developed immune related adverse events (see Table for details). There was minimal overlap between the patients who experienced pneumonitis and immune related toxicity; 2/17 had both pneumonitis and immune related toxicity (hepatitis, thyroiditis). Conclusions: In our early experience with the Pacific regimen, 29% of patients did not complete D due to either toxicity or progression during D administration. Pneumonitis was common (10/42 patients) although there were no grade 3 events. Nearly half of the patients developed an immune-related adverse event. Further analysis is needed to evaluate the real-world toxicity of this treatment as well as oncologic outcomes.[Table: see text]

Effects of the wheel speeds v and disproportionation time during the SC-HDDR process on the properties of Nd-Fe-B magnetic powders are investigated. It is found that the remanence Br, coercivity Hcj and energy products (BH)max of magnetic powders all first increase to the maximum at v=3 m/s, and then decrease with enhancing v. This is attributed to the fact that the SC alloy flakes prepared by the wheel speed of 3 m/s display the optimized microstructure. This optimized SC alloy flakes without homogenizing treatment which carried out a short duration disproportionation treatment can prepare the evidently anisotropic powders. With prolonging disproportionation time, the alignment degree of anisotropy of magnetic powders gradually decreases. This is due to the fact that a short duration disproportionation reaction is beneficial to the disproportionated microstructure displaying the lamella crystals, and the lamella disproportionated microstructure is helpful to the formation of anisotropy. Our results confirm that the anisotropic HDDR Nd-Fe-B magnetic powders prepared directly from the SC alloy flakes without homogenizing treatment can be obtained.

The effects of strip casting (SC)–hydrogenation, disproportionation, desorption, and recombination (HDDR) process parameters on the microstructures of Nd–Fe–B alloy flakes and the magnetic properties of HDDR powders are investigated. The results indicate that the alloy flakes prepared by SC speed of 3 m/s display the optimized microstructure. From this as-cast alloy flakes, anisotropic magnetic powders can be prepared by a slow recombination treatment during the HDDR. The hydrogen pressure of slow recombination treatment (HPSR) has an important influence on the microstructures and magnetic properties of powders. The remanence Br, coercivity Hcj and magnetic energy product (BH)max of the magnetic powders all increase firstly, and then decrease with increasing HPSR. While the HPSR is 0.3 bar, the magnetic properties of the powders reach the maximum values of Br = 1.3 T, Hcj = 954.3 kA/m, (BH)max = 259 kJ/m3, respectively. Our results confirm that highly anisotropic HDDR magnetic powders prepared directly from the as-cast SC alloy flakes without any heat treatment can be obtained.

Using proposed different anisotropy expressions K 1′(r) and K 1″(r) at the grain boundary, we investigate the effect of intergranular phase (IP) on the average anisotropy 〈K 1〉 of grain boundary and the coercivity H c of HDDR (hydrogenation, disproportionation, desorption and recombination) Nd-Fe-B bonded magnet. The results indicate that when the IP’s thickness d is zero, 〈K 1〉 and H c based on K 1′(r) are equal to the corresponding ones based on K 1″(r). While d takes nonzero values, 〈K 1〉 and H c based on K 1″(r) falls and rises more rapidly, respectively, with increasing d. When d is 1 nm and the structure defect thickness r 0 is close to the thickness of domain wall (∼4 nm), the calculated coercivity is consistent well with the avaiable experimental data.

The effect of microstructure on the anisotropy and the coercivity in HDDR Nd–Fe–B magnet has been investigated by putting forward a theoretical anisotropy model influenced simultaneously by both the structure defect and the exchange coupling interaction. The results showed that the coercivity is greatly influenced by both the defect thickness, r 0 , and the anisotropy constant, K 1 (0), at grain surface. Coercivity is determined by the pinning mechanism when K 1 (0) ≤ 0.4 K 1 and r 0 K 1 (0) > 0.4 K 1 . However, it is controlled by the nucleation mechanism when K 1 (0) ≤ 0.4 K 1 and r 0 > 8 nm. For all values of K 1 (0), the coercivity first increases, reaches the maximum and then decreases with increasing r 0 , and its maximum value decreases with increasing K 1 (0). The maximum coercivity is 1102 KA/m while K 1 (0) = 0 and r 0 is close to the thickness of domain wall (∼4 nm), which is consistent with experimental results given by other authors.

The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations of the structure defect factors based on the nucleation and pinning mechanism with 2r 0/lex (where r 0 and lex are the defect thickness and the length of exchange coupling, respectively) were calculated. The results show that the coercivity mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary. For a fixed lex, when 2r 0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r 0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r 0/lex = 1.67. The calculation result is consistent well with the experimental result given by Morimoto et al.

The pinning fields of domain wall at different grain boundary H 0 have been calculated based on the given expression of anisotropy at grain boundary. The coercivity of nanocomposite magnetic materials is thought to be determined by H 0 . Compared with the experiential formula of coercivity, the expression of exchange–coupling coefficient α ex corresponding to pinning fields on grain size D was given too. The results showed that H 0 and α ex increase rapidly first, then increase slowly with increasing D . Our results are consistent with the relative theoretical and experimental results given by others.

Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of j H c =25.6 kOe, B r =13.2 kG and ( BH ) max =39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 °C) is –0.53%/°C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors.

The effect of inter-grain exchange-coupling interaction on the anisotropy of grain in nanoscaled magnets has been investigated by putting forward an expression of anisotropy at grain boundary, K 1 i j ( r ) , which is suitable for different coupling conditions, and expresses well the coherency between soft and hard grains. The average anisotropy of grain 〈 K i j 〉 has been calculated based on K 1 i j ( r ) and the theory of partial exchange-coupling interaction. It has been found that the average anisotropy of hard or soft grain, 〈 K h h 〉 or 〈 K s s 〉 , increases with increasing grain size D monotonously when hard–hard or soft–soft grains couple. When soft–hard grains touch each other, with increasing D , the variation of average anisotropy of soft–hard grain 〈 K 〉 depends on the anisotropy at grain interface K 1 s h ( 0 ) , which denotes the affection degree of hard grain on the anisotropy of soft grain. Compared with other results, it is more reasonable that K 1 s h ( 0 ) ranges from 0.5 K 1 h to 0.7 K 1 h . The variations of anisotropy with D we calculated are consistent with those of coercivities given by other authors when K 1 i j ( 0 ) is fixed in a certain range.

The effect of grain size and distribution on the anisotropy and coercivity of nanocrystalline Nd2Fe14B magnets has been studied by adopting a Gaussian distribution model of grain sizes. The results show that the effective anisotropy Keff and coercivity Hc decrease with reducing average grain size D ¯ , and the decrease is more rapid when D ¯ 15 nm . The nonideal distribution of grain size results in a further decrease of Keff and Hc. The grain size distribution has greater effect on Keff when D ¯ > 15 nm . Taking values of the microstructure constant Pc=0.9 and distribution coefficient σ=0.5, the variation of Hc with D ¯ is consistent with published experiment results. The decrease of Hc is mainly attributed to the decrease of Keff. In order to obtain high effective anisotropy and coercivity in nanocrystalline Nd2Fe14B magnets, D ¯ should be larger than 15 nm and the grain size distribution should be as centralized as possible.

The magnetic powders for sintered NdFeB magnets have been prepared by using the strip casting (SC), hydrogen decrepitation (HD) and jet milling (JM) techniques. The effects of powder flowability and addition of a lubricant on the alignment degree and the hard magnetic properties of sintered magnets have been studied. The results show that the main factor affecting powder flowability is the aggregation of magnetic particles for powders in a loose state, but it is the friction between the powder particles for powders that are in a compact state. The addition of a lubricant with suitable dose can slightly prevent the congregating of powders, obviously decrease the friction between the powder particles, improve the powder flowability, and increase the alignment degree, remanence and energy product density of sintered magnets. Mixing a suitable dose of lubricant and adopting rubber isostatic pressing (RIP) with a pulse magnetic field, we have succeeded in producing the sintered NdFeB magnet with high hard magnetic properties of B r =14.57 KG, j H c =14.43 KOe, ( BH ) max =51.3 MGOe.

Effect of grain size on the effective anisotropy constant between magnetically soft (α-Fe) and hard (Nd2Fe14B) grains in nanocomposite magnets, 〈Ksh〉, has been investigated. The results show that the values of 〈Ksh〉 increase with decreasing size of soft grain, Ds, for the given size of hard grain, Dh. For the given Ds, 〈Ksh〉 increases with increasing Dh, and then approaches a steady value. In order to get a high value of 〈Ksh〉, the hard grain size should be larger than 30 nm and the soft grain size should be about 10 nm.

The influence of exchange–coupling interaction on the effective anisotropy in nanocrystalline Nd2Fe14B permanent material has been investigated. The results show that the exchange–coupling interaction between grains causes a decrease of the effective anisotropy constant, Keff, with decreasing grain size. The variation of Keff with grain size is basically the same as that of coercivity. The decrease of the effective anisotropy is the main reason for the reduction of the coercivity. In order to get high anisotropy or coercivity in nanocrystalline Nd2Fe14B material, the grain size should be larger than 20 nm.

Nd8−xRxFe87.5B4.5 (R=Dy, Sm, x=0–0.6) nanocomposites with different R substitution amounts have been prepared by melt spinning and annealing process. The effects of R substitutions on the exchange-coupling range, effective anisotropy and coercivity were investigated. The experimental results show that Dy addition has no obvious influence on the exchange-coupling range for Nd8−xDyxFe87.5B4.5 nanocomposite. The monotonic increase of coercivity with increasing Dy content in this sample results mainly from the enhancement of anisotropy field by Dy addition. Substitution of Sm for Nd enlarges the exchange-coupling length notably. The coercivity of Nd8−xSmxFe87.5B4.5 increases with Sm content going through a maximum at x=0.3 and then decreases as x>0.3. This variation is owing to the increase of exchange-coupling range and the decrease of the anisotropy field with increasing Sm substitution amount.

Single-phase perovskite-type manganese oxides La0.8 −xNa0.2xMnO3+δ with x = 0.01–0.04 have been prepared by the modified sol–gel method and the influence of the vacancy concentration in the A site on their structures and magnetocaloric properties has systematically been investigated. The experimental results revealed that the samples calcinated at 1573 K remained single phase and were constituted by submicrometre homogeneous particles without deviation from the nominal stoichiometry upon heating. For all the compositions explored in this work, the average manganese oxidation state is practically constant, at 3.37 ± 0.02. Magnetic measurement results show that an appropriate amount of vacancy concentration in the A site is favourable to both the Curie temperature and magnetic entropy change for polycrystalline La0.8−xNa0.2xMnO3+δ compounds. An approximately linear relation between Curie temperature and magnetic entropy change was observed. For La0.771Na0.198Mn1.000 0.029O2.94, the largest value of magnetic entropy change of 3.86 J kg−1 K−1 under a field of 10 kOe and the Curie temperature of 364 K were obtained.

The influence of addition trace elements Co, Ga and Si on the microstructure and the magnetic properties of nanocomposite permanent alloys based on Fe 3 B are investigated. The experimental results show that in comparison to the ternary component (Nd–Fe–B) nanocomposite permanent alloy, the crystallization temperature was decreased, the Curie temperature was increased, the mean grain size of annealed samples was decreased and the exchange coupling interaction between the grains was enhanced for the nanocomposite permanent alloy with these addition elements. These variations cause both coercivity and remanent magnetic induction to increase to different degrees, and so the maximum magnetic energy product of nanocomposite increases.

Taking Nd2Fe14B/α-Fe as example, the exchange-coupling interactions between magnetically soft and hard grains in nanocomposite permanent materials and their effects on the effective anisotropy of materials were investigated. The calculation results expressed that the exchangecoupling interactions are enhanced with the reduction of grain size, and the effective anisotropy of materials decreases with the reduction of grain size and the increase of magnetically soft phase component. The remanence and the effective anisotropy of materials possess the opposite variation trend with the change of grain size and phase ratio. The mean grain size should be in the range of 10–15 nm and the ratio of soft phase should be less than 50% for getting the magnet with high energy product.

The effect of small amount of Co and Dy addition on the magnetic properties of HDDR isotropic Nd-Dy-Fe-Co-B bonded magnets was investigated. The experimental results show that the intrinsic coercivity Hcj and the reversible temperature coefficient of remanence of (Nd0.65 Dy0.35)12.5-(Fe0.9Co0.1)81B6.5 magnet were 1.53 MA·m-1(19.3 kOe) and -0.059%/°C (25–155°C), respectively. The high coercivity and low temperature coefficient of the magnet are due to the enhanced anisotropy field, increased Curie temperature and improved microstructure by Dy and Co addition.

Effects of interactions between grains with different alignment degrees on the coercivity and its angular dependence for Nd 16 (Fe 0.8 Co 0.2 ) 78 B 6 sintered magnets have been studied. The experiments show that the intrinsic coercivity j H c decreases with enhancing grain alignment (decreasing alignment coefficient σ ), the coercivity j H c ( θ ) increases with increasing angle θ between the applied field and the texture axis of the magnets and the variation ratio is larger for the magnets with better grain alignment. The coercivity of the magnets should be determined by the critical field making the moment of individual grains reverse and the interactions between the grains. For the sintered magnets composed of the grains with μm size, the magnetostatic interaction between the grains is stronger than the exchange coupling interaction and it makes the coercivity of magnet increase with increasing alignment coefficient σ . Taking into account the intergrain interactions, the starting field theory of coercivity is in good agreement with the experimental results for Nd 16 (Fe 0.8 Co 0.2 ) 78 B 6 sintered magnets.

Highly transparent conducting Al-doped ZnO films with good adherence and low resistivity have been prepared on polymer substrates by r. f. magnetron sputtering. Mechanically stable polycrystalline conducting ZnO:Al films having a preferred orientation with the (002) planes parallel to the substrates were deposited on polyisocyanate (PI) substrate with resistivities in the range of 4.1×10−3 to 5.110−4 Ω cm, with carrier densities more than 2.6×1020 cm−3 and Hall mobilities between 5.78 and 13.11 cm2 V−1 s−1. The average transmittance exceeded 80% for a 440 nm thick film deposited on polypropylene adipate (PPA) substrate in the visible spectrum. The quality of obtained films depended on substrate temperatures, sputtering power, Ar pressures and compositions of used targets during film fabrication.

The hard magnetic properties and the interactions between the grains for sintered Nd 16 Fe 73 Co 5 B 6 magnets are investigated by using δ M ( H ) plot technique. The results show that the δ M ( H ) plot of NdFeB sintered magnet can explain the effects of the microstructure (size, shape and orientation of the grains) and the intergrain interactions on the hard magnetic properties of the magnet. However, the value of δ M ( H ) is positive when the applied field is not strong enough, which means that the common δ M ( H ) plot theory is not completely consistent with the sintered NdFeB magnet.

Two types of Gaussian distribution function (` θ type’ and `tan θ type') describing the degree of grain alignment in sintered NdFeB magnets have been compared in the distribution coefficient σ (or σ g ), the distribution probability P ( θ ) and the grain alignment dependence of coercivity. The results show that when the grain alignment is good (the ratio of remanence-to-saturation polarization J r / J s ⩾0.90), σ ( σ g ) and P ( θ ) for the two types of Gaussian functions have similar variation tendencies, the calculated values of normalized coercivity based on the starting field theory are basically the same and are consistent with experiments. When the grain alignment is not good ( J r / J s ⩾0.80), the variation tendencies of σ and P ( θ ) are different. In addition, according to `tan θ type’ Gaussian function, the theoretical values of the normalized coercivity based on the starting field theory are still consistent with the experiments, but according to ` θ type’ Gaussian function, the theoretical values seriously deviate from the experiments. This means that the `tan θ type’ Gaussian function is a better texture function for describing the grain alignment.

An expression of anisotropy at grain boundary suitable for different coupling conditions has been given, based on which the effective anisotropy between soft and hard grains 〈 K sh 〉 has been calculated in nanoscaled magnetic materials. The results showed that 〈 K sh 〉 increases rapidly first, then the increase becomes slow, and 〈 K sh 〉 decreases with increasing D s for the same value of D h . 〈 K sh 〉 decreases with increasing D s for all given D h , and the decrease rate becomes slow with increasing D h . In order to obtain higher effective anisotropy between magnetically soft and hard grains, D h should not be less than 25 nm, and D s should be about 10 nm.

The dependence of the hard magnetic properties on the alignment magnetic field for Nd(Fe,Co)B bonded magnets made from anisotropic HDDR powders is studied. The experimental results demonstrate that addition of a little Ga can induce a strong magnetic anisotropy in the HDDR magnetic powders. The application of an alignment magnetic field while the powders are bonded can increase the remanence, the coercivity and the maximum energy product in different degrees and the hard magnetic properties of the magnet are obviously improved with increasing alignment field.

In order to understand the effect of intergranular phase on magnetic properties, we assume that the intergranular phase is nonmagnetic phase and studied the effect of intergranular phase with different thickness d on the effective anisotropy and coercivity of nanocrystalline materials. The results showed that with increasing d , the average anisotropy of grain, 〈 K 〉, of material increases monotonously, while the effective anisotropy, K eff , increases firstly and decreases subsequently, and exhibits maximum value at certain d . The existence of intergranular phase weakens or prevents the exchange-coupling interaction between grains and may result the increase of K eff , and H c of material. The calculated dependence of coercivity on grain size is basically in accordance with the theoretical and experimental results given by other authors.

increases monotonously with an enhancement in the degree of grain alignment (i.e. decrease in the orientation coefficient σ), whereas the intrinsic coercivity jHc decreases monotonously. This dependence leads to a non-monotonic behaviour of the magnetic-inductive coercivity bHc and a saturation of the maximum energy product (BH)max.

The dependence of the macroscopic magnetism for NdCoFeB permanent magnet on the degree of grain alignment has been studied. With an increase in grain alignment degree, the coercivity of the permanent magnet decreases and the remanence increases. The decrease rate of the coercivity is smaller than the increase rate of the remanence. The coercivity Hc(θ) increases with increasing angle θ between the applied field and the texture axis, and for the permanent magnets with good grain alignment the increase rate of Hc(θ) is large. These experimental results can be interpreted by using the starting field theory of coercivity.

The electronic structure of Nd 2 Fe 17 has been calculated using the spin-polarized MS-Xα method based on the assumption that the FeFe and FeNd exchange couplings are dominant. The calculation showed that (i) there are three levels presenting negative exchange couplings between Fe(f) and Fe(c) atoms, and (ii) the crystal structure symmetry of the compound sometimes has a more important effect on the exchange coupling than the atomic spacing. The key factors affecting the magnetic-ordered property of R 2 Fe 17 are discussed.

We build a sandwiched structure model in which the intergranular phase (IP) is homogeneously distributed between soft and hard magnetic grains, and gives a continuously anisotropic expression of the coupling part under the assumption that the IP weakens the intergrain exchange-coupling interaction. Based on the idea that the hardening mechanism is of the pinning type, we calculate the effect of the IP's thickness d and its anisotropy constant K1(0) on the intrinsic coercivity of a nanocomposite permanent material. The calculated results indicate that the domain wall goes twice through irreversible domain wall displacement during the process of moving from soft to hard magnetic grains, and the intrinsic coercivity increases with increasing d, but decreases with increasing K1(0). When d and K1(0) take 2 nm and 0.7Kh, respectively, with Kh being the anisotropy constant in the inner part of the hard magnetic grain, the calculated intrinsic coercivity is in good agreement with the experimental data.