Theoretical Studies on the Structures of Metal String Complexes Crn(L)4Cl2 (n = 3, 5, 7; L = Oligo-α-Pyridylamide) under the Effect of an Electric Field.

To study the electronic structures and properties of [Crn(L)4Cl2] (n = 3, L = dpa: di(2-pyridyl)amido; n = 5, L = tpda: tripyridyldiamido; n = 7, L = teptra: tetrapyridyltriamine) metal string complexes, the BP86 method was used by considering the influence of the electric field (EF) applied parallel to the metal axis. As the EF increases, the migration of more positively charged Crodd is more significant than that of Creven, which results in alternating long-short Cr-Cr bonds. This happens because of the natural charges on the Crodd of 1-3, which are more electropositive than those on Creven. The electrons are pulled to the Cr and Cl(r) atoms at the high-potential side from Cl(l) at the low-potential side by the EF, which leads to asymmetrical FMOs. After the critical electric field (Ec), the configuration turns into a remarkably asymmetric one with alternating Cr-Cr quadruple bonds and weak interactions. The electrons are transferred from equatorial ligands (L) to metal chains. In the meantime, the asymmetry of the FMOs increases and the delocalization is further reduced, which affects the conductivity. Especially for [Cr7(teptra)4Cl2], the delocalized electrons of HOMO are completely transformed into a localized model after the critical electric field. It is observed that this supports the electric switching phenomenon ascribed to the conformations of delocalized and localized electrons. In addition, the longer the length of the metal chain, the smaller the Ec and the easier is for the complexes to be polarized by the EF.

[Laparoscopic management of persistent Müllerian duct syndrome: A case report and pedigree investigation].

OBJECTIVE: To investigate the clinical characteristics, diagnosis, treatment and etiology of persistent Müllerian duct syndrome (PMDS). METHODS: A 3-year-old boy was diagnosed with PMDS according to the clinical manifestations and the results of ultrasonography, laboratory examinations and earlier surgical examination. We performed genetic tests for the patient and his family members, removed the infantile uterus by laparoscopic wedge hysterectomy, biopsied and descended the bilateral testes, and ligated the bilateral internal rings, followed by a retrospective analysis and review of relevant literature. RESULTS: The operation was successful. Gonad biopsy revealed testis tissue, and PMDS was confirmed by intraoperative findings and related examinations. Good bilateral testicular blood supply was found during the 6-month follow-up after surgery. Medical exome sequencing showed the AMHR2 gene c.1499G > A (p.Cys500Tyr) mutant homozygote (A/A) in the patient and his sister and mutant heterozygote (G/A) in his parents. CONCLUSIONS: Laparoscopy is definitely effective for the treatment of PMDS. In surgery, the infantile uterus should be removed in case of good blood supply to the testis, and so were the bilateral testes if they cannot be descended. The homozygous mutation in the AMHR2 gene c. 1499G > A (p. Cys500Tyr) can lead to male PMDS. Pedigree investigation may provide some evidence for possible fertility in PMDS patients.

Comparative Functional Analysis in vitro of 2 COL4A5 Splicing Mutations at the Same Site in 2 Unrelated Alport Syndrome Chinese Families.

X-linked Alport syndrome (XLAS) is a common hereditary nephropathy caused by COL4A5 gene mutations. To date, many splice site mutations have been described but few have been functionally analyzed to verify the exact splicing effects that contribute to disease pathogenesis. Here, we accidentally discovered 2 COL4A5 gene splicing mutations affecting the same residue (c.2917+1G>A and c.2917+1G>C) in 2 unrelated Chinese families. In vitro minigene assays showed that the 2 mutations produced 3 transcripts in H293T cells: one with a 96-bp deletion in exon 33, one with exon 33 skipping, and one with exon 33-34 skipping. However, fragment analysis results showed that the main splicing effects of the 2 mutations were different, the c.2917+1G>A mutation mainly activated a cryptic donor splice site in exon 33 and resulted in the deletion of 96 bp in exon 33, while the c.2917+1G>C mutation mainly caused exon 33 skipping. Our findings indicate that different nucleotide substitutions at the same residue can cause different splicing effects, which may contribute to the variable phenotype of Alport syndrome.

Value of multi-b value DWI in the assessment of early cerebral changes in asymptomatic HIV-positive adolescents.

Background Magnetic resonance imaging (MRI) and functional MRI techniques have been widely used in the diagnosis of human immunodeficiency virus (HIV) infection related diseases. Purpose To explore whether magnetic resonance diffusion-weighted imaging (DWI) can track water molecular diffusion changes in the brain of asymptomatic HIV-positive adolescents. Material and Methods Multi-b value DWI was performed in 23 adolescents, including 15 HIV-positive participants and eight HIV-negative healthy participants. Mean apparent diffusion coefficient (ADC), slow apparent diffusion coefficient (ADCs) values, fast apparent diffusion coefficient (ADCf) values, distribution diffusion coefficient (DDC) values, and heterogeneity index (α) values were calculated within regions of interest (ROIs) in the frontal lobes, basal ganglia, and temporal lobe. Non-parametric tests were then performed. Results In the bilateral frontal lobes, the mean α values in HIV-positive participants were significantly increased compared with those in healthy participants (right side P = 0.001; left side P = 0.000). In the left frontal lobe, the mean DDC value in HIV-positive participants was significantly increased compared with that in healthy participants ( P = 0.008). In the bilateral frontal lobes, the mean ADCf values in HIV-positive participants were significantly lower than those in healthy participants (right side P = 0.011; left side P = 0.008). In the left basal ganglia, the mean α values in HIV-positive participants were significantly lower than that in healthy participants ( P = 0.013). Conclusion Multi-b value DWI could reflect the early characteristics of water molecule diffusion in HIV infections.

[Two novel TSC2 frameshift mutations in tuberous sclerosis complex].

High-throughput sequencing was performed for the peripheral blood DNA from two probands in the family with tuberous sclerosis complex (TSC) to determine the sequences of TSC-related genes TSC1 and TSC2 and their splicing regions and identify mutation sites. Amplification primers were designed for the mutation sites and polymerase chain reaction and Sanger sequencing were used to verify the sequences of peripheral blood DNA from the probands and their parents. The two probands had c.3981-3982 insA (p.Asp1327AspfsX87) and c.4013-4014 delCA (p.Ser1338Cysfs) heterozygous mutations, respectively, in the TSC2 gene. The parents of proband 1 had no abnormalities at these two loci; the mother of proband 2 had c.4013-4014 delCA heterozygous mutation in the TSC2 gene, while the father and the grandparents of proband 2 had no abnormalities. c.3981-3982 insA mutation may cause early coding termination of amino acid sequence at the 1413th site, and c.4013-4014 delCA mutation may cause early coding termination of amino acid sequence at the 1412th site. These two mutations are the pathogenic mutations for families 1 and 2, respectively, and both of them are novel frameshift mutations, but their association with the disease needs to be further verified by mutant protein function cell model and animal model.

[Gene mutation analysis and prenatal diagnosis of four pedigrees with methymalonic aciduria].

OBJECTIVE: To study gene mutations in four pedigrees with methymalonic aciduria, as well as the feasibility of prenatal diagnosis of methymalonic aciduria. METHODS: High-throughput sequencing was performed for related genes in the peripheral blood of children or parents who were diagnosed with methymalonic aciduria to identify the loci with mutations. Then amplification primers were designed for each locus, and PCR and direct sequencing were performed to validate the sequencing in the first generation in the four pedigrees. Whether the mutations were pathogenic were determined with reference to literature review and medical history. In the pedigrees 1, 3, and 4, ultrasound-guided chorionic villi biopsy was performed at weeks 11-13 of pregnancy to perform early prenatal diagnosis. RESULTS: In pedigree 1, c.656A>T and c.729-730insTT heterozygous mutations in the MUT gene were detected in the proband's father and mother, respectively. Early prenatal diagnosis showed c.656A>T and c.729-730insTT double heterozygous mutations in the fetus. The couple decided to terminate pregnancy. In pedigree 2, c.1106G>A and c.755-756insA double heterozygous mutations in the MUT gene were detected in the proband. c.1106G>A came from the father and c.755-756insA came from the mother. In pedigree 3, c.217C>T and c.609G>A double heterozygous mutations in the MMACHC gene were detected in the proband. c.217C>T came from the father and c.609G>A came from the mother. Prenatal diagnosis showed c.609G>A heterozygous mutation in the fetus. The baby was successfully delivered, and the result of umbilical cord blood testing was consistent with the prenatal diagnosis. In pedigree 4, c.609G>A and c.567dupT double heterozygous mutations in the MMACHC gene were detected in the proband. c.609G>A came from the father and c.567dupT came from the mother. Prenatal diagnosis showed c.567dupT heterozygous mutation in the fetus. The baby was successfully delivered, and the result of umbilical cord blood testing was consistent with the prenatal diagnosis. CONCLUSIONS: Identification of gene mutations helps with prenatal diagnosis in pedigrees with methymalonic aciduria.

Molecular characterization and copy number of SMN1, SMN2 and NAIP in Chinese patients with spinal muscular atrophy and unrelated healthy controls.

BACKGROUND: Spinal muscular atrophy (SMA) is caused by SMN1 dysfunction, and the copy number of SMN2 and NAIP can modify the phenotype of SMA. The aim of this study was to analyze the copy numbers and gene structures of SMA-related genes in Chinese SMA patients and unrelated healthy controls. METHODS: Forty-two Chinese SMA patients and two hundred and twelve unrelated healthy Chinese individuals were enrolled in our study. The copy numbers and gene structures of SMA-related genes were measured by MLPA assay. RESULTS: We identified a homozygous deletion of SMN1 in exons 7 and 8 in 37 of 42 patients (88.1%); the other 5 SMA patients (11.9%) had a single copy of SMN1 exon 8. The proportions of the 212 unrelated healthy controls with different copy numbers for the normal SMN1 gene were 1 copy in 4 individuals (1.9%), 2 copies in 203 (95.7%) and 3 copies in 5 (2.4%). Three hybrid SMN genes and five genes that lack partial sequences were found in SMA patients and healthy controls. Distributions of copy numbers for normal SMN2 and NAIP were significantly different (P < 0.001) in people with and without SMA. CONCLUSION: The copy numbers and gene structures of SMA-related genes were different in Chinese SMA patients and healthy controls.

[Genetic and prenatal diagnosis for four families with Williams-Beuren syndrome].

Williams-Beuren syndrome is a common chromosome microdeletion syndrome. Early diagnosis and treatment are very helpful for patients and their families. This study identified the chromosome karyotype in one fetus with ultrasonography abnormalities and three children with developmental disorders from four families. This provided guidance for subsequent pregnancy and prenatal diagnosis by using routine G-banding chromosome karyotyping analysis, multiplex ligation-dependent probe amplification (MLPA) and array comparative genomic hybridization (array-CGH). In one amniotic fluid sample from a pregnant woman with fetal abnormalities on an ultrasound screen and three peripheral blood samples from three children with developmental disorders, the decreased signal of ELN gene probes at 7q11.23 and heterozygous deletions at 7q11.23 were detected by MLPA and array-CGH analysis. The laboratory genetic tests of amniotic fluid samples were normal when the mothers from the four families became pregnant again. It was concluded that MLPA and array-CGH are rapid and accurate tools for the diagnosis of Williams-Beuren syndrome and can provide more information for clinical genetic counseling.

[Application of DHPLC screening TGFBR-3 gene in Chinese women with idiopathic premature ovarian failure].

OBJECTIVE: To evaluate clinical value of denaturing high performance liquid chromatography (DHPLC) used in detecting transforming growth factor beta receptor 3 (TGFBR-3) exons 11 and 12 polymorphism in women with idiopathic premature ovarian failure (POF). METHODS: From Feb. 2009 to Dec. 2011, 110 patients with idiopathic POF undergoing treatment at Shenzhen Maternal & Child Health Institute affiliated to Southern Medical University were enrolled as POF group in this study. In the mean time, 110 women under 40 years old with normal hormonal level and menstrual cycles as control group. The exons 11 and 12 of TGFBR-3 gene polymorphism were screened by using DHPLC, and results of DNA sequencing was as golden standard. Some related indexes were calculated, such as sensitivity, specificity, false negative value, false positive value, Youden index, positive predictive value, and negative predictive value. At the same time, 20% of the tested specimens were chosen randomly and detected by DHPLC again. The value of Kappa index were calculated by comparing the results between the first and second DHPLC analysis. RESULTS: The exon 11 of TGFBR-3 were not identified gene polymorphism and two nucleotide polymorphisms were identified in exon 12. For 2022 T/C polymorphism, the frequencies of CC with 0.9% (1/110), TC with 22.7% (25/110), TT with 76.4% (84/110), C with 12.3% (27/220) and T with 87.7% (193/220) in POF group were significantly different from CC with 0, TC with 9.1% (10/110) and TT with 90.9% (100/110), C with 4.5% (10/220) and T with 95.5% (210/220) in control group (all P<0.05). Allelic and genotypic frequencies of 2161-75 C/T were not differed significantly between the two groups (all P>0.05). As DNA sequencing as golden standard, DHPLC showed that the sensitivity was 100%, specificity was 97.9%, Youden index was 97.9%, positive predictive value was 96.3%, negative predictive value was 100%, and Kappa index was 0.888 (P<0.05). CONCLUSION: DHPLC analysis is higher validity, reliability and practicability method in detecting TGFBR-3 polymorphism in idiopathic premature ovarian failure.

[Cytogenetic and molecular analysis of idic(Yp) in 1 infertile man and 1 prenatal fetus].

OBJECTIVE: To evaluate idic(Yp) in genetic diagnosis by examining 1 infertile man and 1 prenatal fetus using cytogenetic and molecular techniques. METHODS: Following conventional chromosome preparation, we performed G- and C-banding karyo. typing and fluorescence in situ hybridization (FISH). Then we extracted genomic DNA using standard procedures and analyzed it by array-CGH and multiplex ligation-dependent probe amplification (MLPA). RESULTS: Both cases were diagnosed as 45, X/46, X, idic (Yp11.31) mosaicism. The man showed 2 intact copies of Yp11.31-q12 (chrY:2, 710, 250-57, 428, 567, SRY, ZFY, UTY and AZF), and the prenatal fetus exhibited similar findings except a paternal deletion in the AZFc region. CONCLUSION: idic(Y) (p11.31) causes short stature and male infertility. Array-CGH and MLPA can improve the accuracy of the diagnosis of 45, X/46, X, idic (Y) mosaicism, which may contribute to the studies of the phenotype-genotype correlation and clinical genetic counseling.

A mouse model for X-linked Alport syndrome induced by Del-ATGG in the Col4a5 gene.

Alport syndrome (AS) is an inherited glomerular basement membrane (GBM) disease leading to end-stage renal disease (ESRD). X-linked AS (XLAS) is caused by pathogenic variants in the COL4A5 gene. Many pathogenic variants causing AS have been detected, but the genetic modifications and pathological alterations leading to ESRD have not been fully characterized. In this study, a novel frameshift variant c.980_983del ATGG in the exon 17 of the COL4A5 gene detected in a patient with XLAS was introduced into a mouse model in by CRISPR/Cas9 system. Through biochemical urinalysis, histopathology, immunofluorescence, and transmission electron microscopy (TEM) detection, the clinical manifestations and pathological alterations of Del-ATGG mice were characterized. From 16 weeks of age, obvious proteinuria was observed and TEM showed typical alterations of XLAS. The pathological changes included glomerular atrophy, increased monocytes in renal interstitial, and the absence of type IV collagen α5. The expression of Col4a5 was significantly decreased in Del-ATGG mouse model. Transcriptomic analysis showed that differentially expressed genes (DEGs) accounted for 17.45% (4,188/24003) of all genes. GO terms indicated that the functions of identified DEGs were associated with cell adhesion, migration, and proliferation, while KEGG terms found enhanced the degradation of ECM, amino acid metabolism, helper T-cell differentiation, various receptor interactions, and several important pathways such as chemokine signaling pathway, NF-kappa B signaling pathway, JAK-STAT signaling pathway. In conclusion, a mouse model with a frameshift variant in the Col4a5 gene has been generated to demonstrate the biochemical, histological, and pathogenic alterations related to AS. Further gene expression profiling and transcriptomic analysis revealed DEGs and enriched pathways potentially related to the disease progression of AS. This Del-ATGG mouse model could be used to further define the genetic modifiers and potential therapeutic targets for XLAS treatment.

Haplotype and mutation analysis of the TGFBR3 gene in Chinese women with idiopathic premature ovarian failure.

This study screened the TGFBR3 mutations in Chinese patients with idiopathic premature ovarian failure (POF) to gain a better understanding the genetic aetiology of POF. One hundred twelve Chinese patients with idiopathic POF and 110 women from normal controls were examined. The coding region and respective flanking intronic regions of the TGFBR3 gene were amplified by the PCR, and the DNA fragments were directly sequenced. Twenty-eight sequence variants, including 12 novel variants, were identified. These novel variants included three missense mutations, two synonymous mutations, and seven mutations in the intronic region. Three novel exonic missense variants were p.E458G, p.P824L, and p.I836V. The c.566-216G>A, c.566-71C>T, c.2022T>C, c.2502A>G, and c.2568G>A variants represented significantly different genotype distribution between POF cases and the controls. The binary logistic regression analysis of c.566-216G>A, c.566-71C>T, and c.2502A>G variants were significantly associated with the POF patients and the ATTAG haplotype was most significantly over-represented as compared with controls (P = 0.00121). The ATTGG and GCTGG haplotypes were significantly higher in controls than in patients (P = 0.00113 and 0.00055, respectively). Other less frequent haplotypes, such as GCCGA, was only present in the patients (P = 0.00066). GTTGG was only present in the controls (P = 0.00001). Significant diversity of genotype distribution and haplotype analysis suggested that TGFBR3 mutations may be responsible for the genetic aetiology of idiopathic POF in Chinese patients.

FOXE1 polyalanine tract length screening by MLPA in idiopathic premature ovarian failure.

BACKGROUND: FOXE1 is one of the candidate genes for genetic predisposition to premature ovarian failure (POF) and it contains an alanine tract. Our purpose is to assess the influence of length of the alanine tract of FOXE1 on genetic susceptibility to POF. METHODS: The group studied consisted of 110 Chinese patients with idiopathic POF and 110 women from normal controls. The polyalanine tract and flanking sequence of FOXE1 was screened using the Multiple Ligation-dependent Probe Amplification (MLPA) technique and directly sequenced. RESULTS: Three variants of FOXE1-polyalanine length, containing 12, 14, or 16 alanine residues, and 5 different genotypes were identified. There were significantly lower frequencies of the 14/14 genotypes in cases with POF (X2 = 119.73, P = 0.001), as compared with the controls. The incidence of 16/16 genotypes of FOXE1-polyalanine was significantly higher in patients with POF (X2 = 3.403, P = 0.001) in comparison to the controls. The FOXE1 14 alanine allele was significantly less common in the POF patient group (186/220) than the controls (216/220) (X2 = 25.923, P = 0.0001). The FOXE1 16 alanine allele was significantly more common in the POF patient group (28/220) than the controls (4/220) (X2 = 19.412, P = 0.0001). CONCLUSION: This finding provides evidence that polyalanine repeat expansions in FOXE1 may be responsible for the genetic aetiology of POF in Chinese women.

Identification of novel missense mutations of the TGFBR3 gene in Chinese women with premature ovarian failure.

The aim of this study was to assess the association between human transforming growth factor ß receptor, type III (TGFBR3) and idiopathic premature ovarian failure (POF) in a Chinese population. A total of 112 Chinese women with idiopathic POF and 110 normal controls were examined. DNA samples prepared from blood leukocytes were used as templates for polymerase-chain reaction amplification of DNA fragments from TGFBR3. The gene fragments were sequenced. Web-based programs, including PolyPhen, Sorting Intolerant from Tolerant (SIFT), Prediction of Pathological Mutations (PMUT), ScanProsite and ClustalW2, were used to predict the potential functional and structural impacts of the missense variants of TGFBR3. A total of 11 novel variants were identified. Among them, six were found only in the POF patients. Two missense variants, p.E459G and p.P825L, which are conserved in primates, were predicted to have functional and structural impacts on the TGFBR3 protein. The other four variants (c.381+12A>C, c.2431-7A>G, p.S172S and p.C220C) were considered benign. However, further functional studies are necessary to confirm these findings.

[A novel mutation Glu441stop (GAA to TAA) of androgen receptor gene resulting in complete androgen insensitivity syndrome].

OBJECTIVE: To identify the mutation of human androgen receptor gene (AR) in a patient with complete androgen insensitivity syndrome (CAIS). METHODS: DNA sequences of 8 exons and their exon/intron boundaries of the AR gene in the patient were amplified by PCR and directly sequenced. RESULTS: DNA sequencing revealed a nonsense mutation in exon 1, resulting in a change of codon 441 GAA (glutamic acid) to a stop codon (TAA). CONCLUSION: A novel mutation Glu441stop (GAA to TAA) of the androgen receptor gene leading to complete androgen insensitivity syndrome was identified in this study in a Chinese patient. It may help us further understanding the pathogenesis of CAIS.

[Clinical significance of large-scale screening of A1555G mutation of mitochondria DNA for neonates].

OBJECTIVE: To explore the necessity of large-scale screening of mitochondria DNA (mtDNA) A1555G mutation for prevention of aminoglycoside antibiotic induced deafness in newborns. METHODS: One thousand blood filter samples were collected from neonates born in July 2008 in Shenzhen. DNA was extracted with Chelex-100 Resin and amplified by PCR. The mtDNA A1555G mutation was determined by denaturing high-performance liquid chromatography(DHPLC) for PCR products. The positive frequency was calculated. RESULTS: The mitochondrial DNA A1555G mutation was detected in 2 cases of 1000 neonates. The frequency of mutation was 0.2%. CONCLUSION: There is a high frequency of mtDNA A1555G mutation in neonates, the large-scale screening of mtDNAA1555G mutation in newborns might detect the individuals sensitive to aminoglycoside antibiotic, which is helpful to guide a rational medication for newborns and the maternal relatives at high-risk. Furthermore, it might be useful to prevent aminoglycoside antibiotic induced deafness.

[Genetic analysis and prenatal diagnosis for a family with megalencephalic leukoencephalopathy and subcortical cysts].

OBJECTIVE: To identify potential mutation in the MLC1 gene in a Chinese family affected with megalencephalic leukoencephalopathy and subcortical cysts (MLC), and to provide prenatal diagnosis. METHODS: Genomic DNA of the patients, their parents and younger sister were extracted from peripheral blood. That of the fetus was extracted from an amniotic fluid sample. A total of 12 exons and at least 100 bp flanking the intronic sequence of the MLC1 gene were amplified with PCR. MLC1 mutations were screened by sequencing. Linkage analysis was performed for the family to assure accuracy of prenatal diagnosis. RESULTS: The two patients were both heterozygote for c.177_178delG (p.Ser60AlafsX5) mutation in exon 2 and c.598-2A>C change in intron 7. The c.177_178delG mutation was inherited from the father, and the c.598-2A>C mutation was inherited from the mother. The younger sister and the fetus have both inherited c.177_178delG from the father but did not inherit c.598-2A>C from the mother. Prenatal diagnosis suggested the fetus to be a carrier for a MLC1 mutation. Linkage analysis was consistent with the result of mutation detection. The fetus was born normal as predicted. CONCLUSION: The c.598-2A>C is a novel splicing mutation. Prenatal diagnosis through DNA sequencing and linkage analysis were performed for the first time on Chinese patients with MLC.

[The effect of recasting on microstructure of dental ceramic alloys].

PURPOSE: To investigate the effects of recasting on metallographic microstructure of cobalt-chromium(Co-Cr), commercially pure titanium(cpTi), palladium-copper-gallium(Pd-Cu-Ga), aurum-platinum(Au-Pt) ceramic alloys. METHODS: Without adding new alloys, Co-Cr, cpTi, Pd-Cu-Ga and Au-Pt ceramic alloys were recasted for 1-3 times under the circumstance of vacuum compressive casting with argon. Before each recasting, these 4 ceramic alloys casted previously were treated by the most appropriate way which has been reported by our previous study. According to GB/T13298-2015 standards, the specimens of 4 ceramic alloys after recasting 1-3 times were grinded, polished, and etched and then the metallographic microstructure of them were determined by a metallographic microscope or scanning electron microscopy(SEM). RESULTS: With the increase of recasting times, the microstructure of Co-Cr ceramic alloy showed grain growth, grain matrix increase, and the intermetallic compound in the grain boundary increase, the microstructure of the cpTi ceramic alloy showed grain growth. The samples of cpTi ceramic alloy recasting twice appeared shaft tendency, and the ones which were recasted 3 times were compound of α-phase and ß-phase. The microstructure of the Pd-Cu-Ga ceramic alloy showed grain growth slightly after casting 2-3 times, while no significant change was found on the microstructure of the Au-Pt ceramic alloy. CONCLUSIONS: Recasting changes the microstructure of Co-Cr, cpTi, and Pd-Cu-Ga ceramic alloys, and the ceramic alloys may recycled by the manufacturers.

[Effects of recasting in vacuum with argon on the chemical composition of ceramic alloys].

OBJECTIVE: This study aimed to determine the effect of recasting in vacuum with argon on the chemical composition of cobalt-chromium (Co-Cr), commercially pure titanium (cpTi), palladium-based (Pd-based), and aurum-platinum (Au-
Pt) ceramic alloys. METHODS: Without adding new alloys, Co-Cr, cpTi, Pd-based, and Au-Pt ceramic alloys were recast one to three times under the condition of vacuum compressive casting with argon. Before recasting, four previously cast ceramic alloys were treated with the corresponding method. After polishing, the chemical composition of the four ceramic alloys recasted one to three times were determined by energy-dispersive spectrometry. RESULTS: No significant difference was observed in the chemical composition of the four ceramic alloys recast 1-3 times (P>0.05). CONCLUSIONS: Under the condition of vacuum with argon, the recasting had no obvious influence on the chemical composition of Co-Cr, cpTi, Pd-based, and Au-Pt ceramic alloys.

Enhancement of unidirectional transmission through the coupling of nonlinear photonic crystal defects.

We investigate the unidirectional transmission behavior of coupled photonic crystal defects with nonlinearity by using the coupled mode theory, focusing on how to enhance the transmission contrast. Although the unidirectional transmission originates from the asymmetric configuration and nonlinear property of the structure, it is revealed that the maximum transmission contrast depends mainly on two linear factors. For two coupled defects, they are the highest order of the frequency detuning appearing in the transmission formula and the frequency splitting due to the coupling. Our analyses are supported by the numerical simulations based on the finite-difference time-domain technique. An enhancement of the maximum transmission contrast by an order of magnitude is achieved in the structure consisting of two coupled defects.