Material and Interface Engineering for High-Performance Perovskite Solar Cells: A Personal Journey and Perspective

Hybrid organic-inorganic perovskite solar cells (PSCs) have become a shining star in the photovoltaic field due to their spectacular increase in power conversion efficiency (PCE) from 3.8 % to over 23 % in just few years, opening up the potential in addressing the important future energy and environment issues. The excellent photovoltaic performance can be attributed to the unique properties of the organometal halide perovskite materials, including high absorption coefficient, tunable bandgap, high defect tolerance, and excellent charge transport characteristics. The authors entered this field when pursuing research on dye-sensitized solar cells (DSCs) by leveraging nanorods arrays for vectorial transport of the extracted electrons. Soon after, we and others realized that while the organometal halide perovskite materials have excellent intrinsic properties for solar cells, interface engineering is at least equally important in the development of high-performance PSCs, which includes surface defect passivation, band alignment, and heterojunction formation. Herein, we will address this topic by presenting the historical development and recent progress on the interface engineering of PSCs primarily of our own group. This review is mainly focused on the material and interface design of the conventional n-i-p, inverted p-i-n and carbon electrode-based structure devices from our own experience and perspective. Finally, the challenges and prospects of this area for future development will also be discussed.

Evaluation of genotyping concordance for commercial bovine SNP arrays using quality-assurance samples

SNP arrays are widely used in genetic research and agricultural genomics applications, and the quality of SNP genotyping data is of paramount importance. In the present study, SNP genotyping concordance and discordance were evaluated for commercial bovine SNP arrays based on two types of quality assurance (QA) samples provided by Neogen GeneSeek. The genotyping discordance rates (GDRs) between chips were on average between 0.06% and 0.37% based on the QA type I data and between 0.05% and 0.15% based on the QA type II data. The average genotyping error rate (GER) pertaining to single SNP chips, based on the QA type II data, varied between 0.02% and 0.08% per SNP and between 0.01% and 0.06% per sample. These results indicate that genotyping concordance rate was high (i.e. from 99.63% to 99.99%). Nevertheless, mitochondrial and Y chromosome SNPs had considerably elevated GDRs and GERs compared to the SNPs on the 29 autosomes and X chromosome. The majority of genotyping errors resulted from single allotyping errors, which also included the opposite instances for allele 'dropout' (i.e. from AB to AA or BB). Simultaneous allotyping errors on both alleles (e.g. mistaking AA for BB or vice versa) were relatively rare. Finally, a list of SNPs with a GER greater than 1% is provided. Interpretation of association effects of these SNPs, for example in genome-wide association studies, needs to be taken with caution. The genotyping concordance information needs to be considered in the optimal design of future bovine SNP arrays.

Abstract P2-01-20: LAP2alpha, a novel tumor marker candidate is related to metastasis of breast cancer

Background: To date, there is no suitable serum marker for diagnosis and prognosis of breast cancer. In our early research, a new tumor marker candidate of breast cancer whose molecular weight was 5.6 kDa was screened from serum using mass spectrometry technology. It was decoded to be a fragment of isoform alpha of lamina-associated polypeptide 2 (LAP2α). The survival analysis revealed that LAP2α was over-expressed in breast cancer patients and indicated poor prognosis.

Materials and Methods: Immunohistochemistry (IHC) was utilized to evaluate LAP2α expression in paired primary breast tumor, metastasis of axillary lymph node and ipsilateral normal breast tissue of 29 breast cancer patients. An inhibition plasmid vector of LAP2α-small hairpin RNA (LAP2α-shRNA) was constructed and transfected into MCF-7 cells. The abilities of cell proliferation and metastasis were assessed both in vitro and in vivo. The association of LAP2α with epithelial-to-mesenchymal transition (EMT) was determined by western blot.

Results: LAP2α expression of paired tissue descended in order of metastasis of axillary lymph node (21/29, 72.4%), primary breast tumor (11/29, 37.9%) and ipsilateral normal breast tissue (4/29, 13.8%) (P<0.05 in comparisons between each two groups). CCK-8 experiments on transfected and control cells showed that inhibition of LAP2α could not influence cell proliferation. Transwell and matrigel-transwell assays indicated that inhibition of LAP2α could significantly reduce cell migration and invasion abilities. In vivo experiments utilizing subcutaneous xenograft model and tail vein-injection mouse model revealed that the down-regulation of LAP2α might suppress tumorigenesis and metastasis of breast cancer. Western blot suggested that down regulation of LAP2α increased the E-cadherin expression level but repressed N-cadherin and vimentin expression levels.

Conclusions: A novel tumor marker candidate, LAP2α is related to metastasis of breast cancer both in clinical samples and tissue culture experiments. Inhibition of LAP2α could suppress aggressiveness and metastasis of breast cancer probably via EMT suppression.

Funding: The Natural Science Foundation of Zhejiang Province of China (No. LY14H160030 and LY13H160011), the National Program on Key Basic Research Project of China (973 Program; No. 2014CB542003), the National Natural Science Foundation of China (No. 30801341) and Zheng Shu Elite Scholarship for Clinical Medicine.

Citation Format: Hu Y, Qiu J, Zhou M, Li X, Huang Y. LAP2alpha, a novel tumor marker candidate is related to metastasis of breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-20.

Abstract P3-03-20: Which biopsy is preferred to stage the axilla under ultrasound guidance in early breast cancer patients: Fine-needle aspiration cytology or core needle biopsy?

Background:

Preoperative axillary ultrasound (AUS) offers the potential to identify clinically axillary negative patients with axillary lymph node (ALN) metastasis directly to axillary lymph node dissection (ALND) with avoid of unnecessary sentinel lymph node biopsy (SLNB) except Z0011 candidates. Which biopsy should be preferred is pendent with lack of enough prospective studies. The purpose of our study was to compare the accuracy of ultrasound guided fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB) for the designated ALN prospectively.

Methods:

Consecutive patients with histologically confirmed breast cancer from April, 2010 to December, 2014 were preliminary screened for our study. All the candidate patients were prospectively assessed by ipsilateral AUS before initial treatment regardless of clinical ALN status.Abnormal lymph nodes were characterized by round shape with uniform or eccentric thickening, focal bulging or irregularity of the cortex displacement, obliteration of the hilum; or total loss of recognizable lymph node architecture. If suspicious ALN was identified, both ultrasound-guided FNAC and CNB were performed for the same designated ALN.The diameter in longitudinal section, transverse section and maximum cortical thickness of the target node was recorded. When more than one abnormal lymph node was present, the most abnormal-appearing node was sampled. The target tissue for biopsy was hypoechoic thickened cortex. Patients with a positive FNAC/CNB underwent ALND, and those with a negative FNAC and CNB biopsy or without suspicious ALN by AUS underwent SLNB. The paired parameters of FNAC and CNB were compared using McNemar's exact test.

Results:

705 consecutive patients were screened and 558 patients (561 axillae) underwent AUS evaluation with confirmed ALN pathological results.145 patients (146 axillae) with both FNAC and CNB were finally enrolled. Final histopathological results showed that 83.6% (122/146) were node positive (5 micro-metastases were considered negative). Sensitivity of FNAC and CNB was 67.2% (82/122) and 91.8% (112/122). Overall accuracy of FNAC and CNB was 72.6% (106/146) and 93.2% (136/146). Negative predictive value (NPV) of FNAC and CNB was 37.5% (24/64) and 70.6% (24/34). There was significant difference in sensitivity, overall accuracy and NPV between FNAC and CNB (p<0.001). 80.6% (29/36) FNAC negative and CNB positive patients have ALN cortical thickness of 3.3-7.2 mm.

Conclusion:

CNB is more sensitive and accurate than FNAC to stage the axilla under ultrasound guidance in operable breast cancer patients, especially in patients with ALN cortical thickness of 3.3-7.2 mm.

Citation Format: Zhou M, Qiu J, Chen J, Hu Y, Deng Y, Zheng S. Which biopsy is preferred to stage the axilla under ultrasound guidance in early breast cancer patients: Fine-needle aspiration cytology or core needle biopsy? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-20.

Validation of a predictive method for sunscreen formula evaluation using gene expression analysis in a Chinese reconstructed full-thickness skin model

OBJECTIVE

This study aimed to establish a predictive in vitro method for assessing the photoprotective properties of sunscreens using a reconstructed full-thickness skin model.

MATERIALS AND METHODS

A full-thickness skin model reconstructed with human fibroblasts and keratinocytes isolated from Chinese skin was exposed to daily UV radiation (DUVR). We examined the transcriptomic response, identifying genes for which expression was modulated by DUVR in a dose-dependent manner. We then validated the methodology for efficacy evaluation of different sunscreens formulas.

RESULTS

The reconstructed skin model was histologically consistent with human skin, and upon DUVR exposure, the constituent fibroblasts and keratinocytes exhibited transcriptomic alterations in pathways associated with oxidative stress, inflammation and extracellular matrix remodelling. When used to evaluate sunscreen protection on the model, the observed level of protection from UV-induced gene expression was consistent with the corresponding protection factors determined clinically and allowed for statistical ranking of sunscreen efficacy.

CONCLUSIONS

Within this study we show that quantification of gene modulation within the reconstructed skin model is a biologically relevant approach with sensitivity and predictability to evaluate photoprotection products.

Flexible layer-structured Bi2Te3 thermoelectric on a carbon nanotube scaffold

Inorganic chalcogenides are traditional high-performance thermoelectric materials. However, they suffer from intrinsic brittleness and it is very difficult to obtain materials with both high thermoelectric ability and good flexibility. Here, we report a flexible thermoelectric material comprising highly ordered Bi₂Te₃ nanocrystals anchored on a single-walled carbon nanotube (SWCNT) network, where a crystallographic relationship exists between the Bi₂Te₃ <[Formula: see text]> orientation and SWCNT bundle axis. This material has a power factor of ~1,600 μW m^-1 K^-2 at room temperature, decreasing to 1,100 μW m^-1 K^-2 at 473 K. With a low in-plane lattice thermal conductivity of 0.26 ± 0.03 W m^-1 K^-1, a maximum thermoelectric figure of merit (ZT) of 0.89 at room temperature is achieved, originating from a strong phonon scattering effect. The origin of the excellent flexibility and thermoelectric performance of the Bi₂Te₃-SWCNT material is attributed, by experimental and computational evidence, to its crystal orientation, interface and nanopore structure. Our results provide insight into the design and fabrication of high-performance flexible thermoelectric materials.

Comparative transcriptome profiles of Lindian chicken eyelids identify melanin genes controlling eyelid pigmentation

1. During the long history of chicken domestication, eyelid colour, like skin colour and shank colour, has been one of the physical traits of Chinese indigenous chickens that influence consumer buying behaviour. In China, the Lindian chicken, which has coloured feathers, is renowned for the appetizing flavour of its meat and eggs, and its eyelid colours vary from deep (black) to light shades (light yellow). 2. To investigate genes involved in eyelid colour, the expression profiles of black and light-yellow eyelids of Lindian chickens were analysed with transcriptome sequencing. 3. A total of 13 466 genes were detected in the eyelids, among which 14 were differentially expressed. Among these differentially expressed genes (DEGs), three key genes, premelanosome protein (PMEL), dopachrome tautomerase (DCT), and tyrosinase (TYR), encoded proteins that positively regulate melanogenesis and melanin deposition. PMEL, DCT and TYR were expressed much more strongly in the black eyelids than in the light-yellow eyelids. A Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that tyrosine metabolism and melanogenesis genes were significantly enriched among these DEGs (corrected P < 0.05). 4. In conclusion, melanin may be one of the main factors involved in Lindian chicken eyelid colour. Furthermore, these results provide a valuable resource for the future study of the physical traits of Lindian chicken.

Insulin and leptin excite anorexigenic pro-opiomelanocortin neurones via activation of TRPC5 channels

Pro-opiomelanocortin (POMC) neurones within the hypothalamic arcuate nucleus are vital anorexigenic neurones. Both the insulin receptor and leptin receptor are coupled to activation of phosphatidylinositide-3 kinase (PI3K) to regulate multiple functions that increase POMC neuronal excitability. Using whole-cell recording in several mammalian species, we have found that both insulin and leptin depolarised POMC neurones via activation of transient receptor potential (TRPC)5 channels. TRPC5 channels have been rigorously characterised as the downstream effector based on their biophysical properties, pharmacological profile, and localisation by immunocytochemistry and single-cell reverse transcriptase-polymerase chain reaction. By contrast, insulin and leptin hyperpolarise and inhibit neuropeptide Y/agouti-related peptide neurones via activation of KATP channels. As proof of principle, insulin given i.c.v. robustly inhibits food intake and increases O2 utilisation, CO2 production and metabolic heat production. Therefore, these findings indicate that the depolarisation/excitation of POMC neurones by insulin and leptin is preserved across mammalian species and the activation of TRPC5 channels is likely a major mechanism by which insulin and leptin regulate energy homeostasis in mammals.

Identification and characterization of a new three-component nicotinic acid hydroxylase NahAB1 B2 from Pusillimonas sp. strain T2

Nicotinic acid (NA) is ubiquitous in nature and its microbial degradation mechanisms are diverse. In this study, Pusillimonas sp. strain T2 was found to be capable of utilizing NA as sole carbon and nitrogen sources. This strain could completely degrade 300 mg l^-1 NA within 3·5 h at 30°C and pH 7·0 and one of the degradation intermediate of NA was identified as 6-hydroxynicotinic acid (6HNA). The draft genome sequences of strain T2 were determined to have a total length of 3·3 M bp and 3054 proteins were predicted. The encoding genes of three-component NA hydroxylase (NahAB₁ B₂ ) genes were identified. The nahAB₁ B₂ genes were heterologously expressed in the non-NA-degrading Shinella sp. strain HZN7. The recombinant HZN7-pBBR-nahAB₁ B₂ converted NA into equimolar 6HNA, while the recombinants HZN7-pBBR-nahAB₁ (lacking component B₂ ) and HZN7-pBBR-nahAB₂ (lacking component B₁ ) could not convert NA. Cell-free extracts of HZN7-pBBR-nahAB₁ B₂ exhibited NA hydroxylase activity. After addition of an artificial electron acceptor (such as phenazine methosulphate, PMS), the NA hydroxylase activity was significantly increased. The K_m and V_max values for NA were 65·94 μmol l^-1 and 260·80 ± 5·69 mU mg^-1 , respectively, using PMS as an electron acceptor. This study provides a novel insight into the NA degradation by bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

Nicotinic acid (NA) serves as a model system for the degradation of N-heterocyclic aromatic compounds and the microbial degradation mechanisms are diverse. This is the first time that a three-component hydroxylase has been identified. This study provides a novel insight into the NA degradation by bacteria.

Cellulose Fiber-Based Hierarchical Porous Bismuth Telluride for High-Performance Flexible and Tailorable Thermoelectrics

Porous modification is a general approach to endowing the rigid inorganic thermoelectric (TE) materials with considerable flexibility, however, by which the TE performances are severely sacrificed. Thus, there remains an ongoing struggle against the trade-off between TE properties and flexibility. Herein, we develop a novel strategy to combine Bi₂Te₃ thick film with ubiquitous cellulose fibers (CFs) via an unbalanced magnetron sputtering technique. Owing to the nano-micro hierarchical porous structures and the excellent resistance to crack propagation of the Bi₂Te₃/CF architectures, the obtained sample with a nominal Bi₂Te₃ deposition thickness of tens of micrometers exhibits excellent mechanically reliable flexibility, of which the bending deformation radius could be as small as a few millimeters. Furthermore, the Bi₂Te₃/CF with rational internal resistance and tailorable shapes and dimensions are successfully fabricated for practical use in TE devices. Enhanced Seebeck coefficients are observed in the Bi₂Te₃/CF as compared to the dense Bi₂Te₃ films, and the lattice thermal conductivity is remarkably reduced due to the strong phonon scattering effect. As a result, the TE figure of merit, ZT, is achieved as high as ∼0.38 at 473 K, which competes with the best flexible TEs and can be further improved by optimizing the carrier concentrations. We believe this developed technique not only opens up a new window to engineer flexible TE materials for practical applications but also promotes the robust development of the fields, such as paper-based flexible electronics and thin-film electronics.

Solution and gas phase evidence of anion binding through the secondary bonding interactions of a bidentate bis-antimony(iii) anion receptor

Solution and gas phase evidence of halide binding to a bis-antimony(iii) anion receptor is demonstrated through NMR titrations and ESI-MS.

Quantification of classical HLA class I mRNA by allele-specific, real-time polymerase chain reaction for most Han individuals

Recent studies have shown that expression levels of different alleles at the same HLA class I locus can vary dramatically, which might have a broad influence on human disease. However, precise quantification of the relative expression level of each HLA allele is challenging, because distinguishing different alleles on the same locus is difficult. Here, we developed a series of allele-specific, real-time polymerase chain reaction assays for quantifying HLA class I allele mRNA in most Han individuals. The alleles of almost all heterozygous genotypes with a frequency higher than 0.5% in our population (78 alleles on HLA-A locus, 124 alleles on HLA-B locus, and 74 alleles on HLA-C locus) were specifically amplified. The specificity of the amplification was strictly validated by setting the corresponding negative control for each allele of each genotype. The amplification efficiency of each reaction was determined, and the slopes of the reactions were compared. This study provides a tool for detecting the comprehensive expression profile of HLA class I alleles and will be useful not only for the investigation of the molecular mechanism underlying HLA allele expression regulation but also for exploration of immunological mechanisms involving HLA expression in the fields of tumour immune evasion, viral infection, auto-immune disorders, and graft vs host disease after haematopoietic stem cell transplantation.