Identification and characterization of candidate genes for primary root length in Asiatic cotton (Gossypium arboreum L.).

KEY MESSAGE: One major gene controlling primary root length (PRL) in Gossypium arboreum is identified and this research provides a theoretical basis for root development for cotton. Primary root elongation is an essential process in plant root system structure. Here, we investigated the primary root length (PRL) of 215 diploid cotton (G. arboreum) accessions at 5, 8, 10, 15 days after sowing. A Genome-wide association study was performed for the PRL, resulting in 49 significant SNPs associated with 32 putative candidate genes. The SNP with the strongest signal (Chr07_8047530) could clearly distinguish the PRLs between accessions with two haplotypes. GamurG is the only gene that showed higher relative expression in the long PRL genotypes than the short PRL genotypes, which indicated it was the most likely candidate gene for regulating PRL. Moreover, the GamurG-silenced cotton seedlings showed a shorter PRL, while the GamurG-overexpressed Arabidopsis exhibited a significantly longer PRL. Our findings provide insight into the regulation mechanism of cotton root growth and will facilitate future breeding programs to optimize the root system structure in cotton.

Multistage temporal transcriptomic atlas unveils major contributor to reproductive phase in upland cotton.

Flowering is a major developmental transition in plants, but asynchronous flowering hinders the utilization of wild cotton relatives in breeding programs. We performed comparative transcriptomic profiling of early- and late-flowering Gossypium hirsutum genotypes to elucidate genetic factors influencing reproductive timing. Shoot apices were sampled from the photoperiod-sensitive landrace G. hirsutum purpurascens (GhP) and early-maturing variety ZhongMianSuo (ZMS) at five time points following the emergence of sympodial nodes. RNA-sequencing revealed extensive transcriptional differences during floral transition. Numerous flowering-associated genes exhibited genotype-specific expression, including FLOWERING LOCUS T (FT) homologs upregulated in ZMS. FT-interacting factors like SOC1 and CO-like also showed higher expression in ZMS, implicating florigen pathways in early flowering. Additionally, circadian clock and light signalling components were misregulated between varieties, suggesting altered photoperiod responses in GhP. Weighted co-expression network analysis specifically linked a module enriched for circadian-related genes to GhP's late flowering. Through an integrated transcriptome analysis, we defined a regulatory landscape of reproductive phase change in cotton. Differentially expressed genes related to photoperiod, circadian clock, and light signalling likely contribute to delayed flowering in wild cottons. Characterization of upstream flowering regulators will enable modifying photoperiod sensitivity and expand germplasm use for cotton improvement. This study provides candidate targets for elucidating interactive mechanisms that control cotton flowering time across diverse genotypes.

Silencing of GhORP_A02 enhances drought tolerance in Gossypium hirsutum.

BACKGROUND: ORP (Oxysterol-binding protein-related proteins) genes play a role in lipid metabolism, vesicular transferring and signaling, and non-vesicular sterol transport. However, no systematic identification and analysis of ORP genes have been reported in cotton. RESULT: In this study, we identified 14, 14, 7, and 7 ORP genes in G. hirsutum, G. barbadense, G. arboreum, and G. raimondii, respectively. Phylogenetic analysis showed that all ORP genes could be classified into four groups. Gene structure and conserved motif analysis suggest that the function of this gene family was conserved. The Ka/Ks analysis showed that this gene family was exposed to purifying selection during evolution. Transcriptome data showed that four ORP genes, especially GhORP_A02, were induced by abiotic stress treatment. The cis-acting elements in the ORP promoters were responsive to phytohormones and various abiotic stresses. The silenced plants of GhORP_A02 were more sensitive to drought stress when compared to control. CONCLUSION: The major finding of this study shed light on the potential role of ORP genes in abiotic stress and provided a fundamental resource for further analysis in cotton.

Remote preconditioning combined with nebulized budesonide alleviate lipopolysaccharide induced acute lung injury via regulating HO-1 and NF-κB in rats.

BACKGROUND: Acute lung injury (ALI) may result in severe systemic inflammation and is life-threatening. Remote inflammatory preconditioning (RIPC) has been confirmed to have an endogenous protective effect against ALI. Budesonide (BS) is a potent corticosteroid typically administered through nebulization that reduces inflammation in the lungs. We speculate that the combined use of RIPC and nebulized BS has a stronger protective effect on ALI. METHODS: 48 Sprague-Dawley male rats were used for the experiments. Animals were divided evenly and randomly into three groups, control (NS injection), LPS (LPS injection), and RIPC (LPS injection with RIPC). Each group was then divided into two subgroups with inhalation of nebulized normal saline (NS) or BS. Prior to injection of LPS, RIPC was performed by tying and untying the right hind limb for three cycles of 5 min each. Following LPS injection, animals in each subgroup were placed in a same cage for nebulized inhalation. Animals were sacrificed 6 h after LPS injection. Histological evaluation of ALI and lung wet-to-dry weight ratio were measured. Serum lactate acid, inflammatory cytokines, oxidative stress indicators were detected. The expression of HO-1, NF-κB p65 and p-p65 was measured by western blotting. RESULTS: RIPC combined with nebulized BS significantly attenuated the LPS-induced ALI in rats. Reduction of MDA, increasing of SOD activity were found significantly improved by the joint strategy. TNF- and IL-1ß rise brought on by LPS was reduced, but IL-10 production dramatically enhanced when compared to the LPS group. The expression of HO-1 was significantly increased by RIPC combined with nebulized BS while the expression of NF-κB p65 and p-p65 was decreased when compared with the LPS group. CONCLUSION: RIPC combined with nebulized budesonide is protective for ALI induced by LPS in rats.

Transcriptomic analysis reveals the beneficial effects of salt priming on enhancing defense responses in upland cotton under successive salt stress.

Priming-mediated stress tolerance in plants stimulates defense mechanisms and enables plants to cope with future stresses. Seed priming has been proven effective for tolerance against abiotic stresses; however, underlying genetic mechanisms are still unknown. We aimed to assess upland cotton genotypes and their transcriptional behaviors under salt priming and successive induced salt stress. We pre-selected 16 genotypes based on previous studies and performed morpho-physiological characterization, from which we selected three genotypes, representing different tolerance levels, for transcriptomic analysis. We subjected these genotypes to four different treatments: salt priming (P0), salt priming with salinity dose at 3-true-leaf stage (PD), salinity dose at 3-true-leaf stage without salt priming (0D), and control (CK). Although the three genotypes displayed distinct expression patterns, we identified common differentially expressed genes (DEGs) under PD enriched in pathways related to transferase activity, terpene synthase activity, lipid biosynthesis, and regulation of acquired resistance, indicating the beneficial role of salt priming in enhancing salt stress resistance. Moreover, the number of unique DEGs associated with G. hirsutum purpurascens was significantly higher compared to other genotypes. Coexpression network analysis identified 16 hub genes involved in cell wall biogenesis, glucan metabolic processes, and ribosomal RNA binding. Functional characterization of XTH6 (XYLOGLUCAN ENDOTRANSGLUCOSYLASE/HYDROLASE) using virus-induced gene silencing revealed that suppressing its expression improves plant growth under salt stress. Overall, findings provide insights into the regulation of candidate genes in response to salt stress and the beneficial effects of salt priming on enhancing defense responses in upland cotton.

Crystal Growth, Characterization, and Properties of Nonlinear Optical Crystals of LixAg1-xGaSe2 for Mid-Infrared Applications.

LixAg1-xGaSe2 is a new series of solid solution crystals that has a large nonlinear optical (NLO) coefficient and laser-induced damage threshold (LIDT). It has great application prospects in mid-infrared laser frequency conversion. In this work, LixAg1-xGaSe2 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1) crystals (Φ 16 mm × 40 mm) were grown by the improved Bridgeman method in a four-zone furnace. It is found that the LixAg1-xGaSe2 (x = 0.2-0.8) crystals keep the same tetragonal symmetry with AgGaSe2 and the melting and solidification temperature increase with the Li content. Because the as-grown crystals are almost opaque in the visible-NIR range, an annealing experiment is necessary. After annealing, the transmittance is improved significantly, which can meet the application requirements. The band gap is changed by annealing atmosphere; for instance, the band gap of Li0.6Ag0.4GaSe2 annealed in a LiGaSe2 powder atmosphere increases from 2.35 to 2.56 eV, while the band gap of LiGaSe2 annealed in vacuum decreases from 3.39 to 3.01 eV. Finally, the LixAg1-xGaSe2 shows an extreme SHG response, especially Li0.8Ag0.2GaSe2, which has about five times that of LiGaSe2, proving the promising NLO properties.

Crystal Growth, Thermal Treatment, and Characterization of Nonlinear Optical Crystal LiGa0.5In0.5Se2 for Mid-infrared Applications.

LiGa0.5In0.5Se2 is a new quaternary nonlinear optical crystal for the mid-IR application grown as a mixed crystal of the LiGaSe2-LiInSe2 solid-solution system. It is transparent in the 0.47-14 µm range and has an appropriate bandgap and a lower melting point than LiGaSe2 and LiInSe2. It is more technological about the growth process since its homogeneity range is broader in the phase diagram. In this work, we have synthesized the LiGa0.5In0.5Se2 polycrystal by the two-zone temperature method. LiGa0.5In0.5Se2 single crystals (Φ26 mm × 50 mm) were grown through the modified Bridgman method with the c-axis seed crystal which has the smallest thermal expansion coefficient of the three main axes in 293-773 K. The crystal structure was studied by X-ray diffraction and the Rietveld refinement method. Due to the low transmittance of the as-grown crystals, a systematic thermal treatment experiment was carried out. In the annealing experiment, the crystal surface is seriously enriched with selenium due to the thermal diffusion of selenium, resulting in the crystal opacity and cracking, while after vacuum quenching at 873 K, the transmittance of the LiGa0.5In0.5Se2 crystal wafer was greatly improved, the bandgap shows a large increase from 2.13 to 2.51 eV, and the quenched crystal shows strong SHG response (×1.91 LiGaSe2). The chemical states and vibration modes of surface elements for both conditions were characterized by X-ray photoelectron and Raman spectra. Density functional theory calculations were carried out to simulate the phonon spectrum and phonon density of states, which can help to study the phonon vibration modes in the lattice.

Integrating Genome-wide association and whole transcriptome analysis to reveal genetic control of leaf traits in Gossypium arboreum L.

Leaves are important organs for crop photosynthesis and transpiration, and their morphological characteristics can directly reflect the growth state of plants. Accurate measurement of leaf traits and mining molecular markers are of great significance to the study of cotton growth. Here, we performed a Genome-wide association study on 7 leaf traits in 213 Asian cotton accessions. 32 significant SNPs and 44 genes were identified. A field experiment showed significant difference in leaf hair and leaf area between DPL971 and its natural mutant DPL972. We also compared the leaf transcriptome difference between DPL971 and DPL972, and found a batch of differentially expressed genes and non-coding RNAs (including lncRNAs, microRNAs, and circRNAs). After integrating the GWAS and transcriptome results, we finally selected two coding genes (Ga03G2383 and Ga05G3412) and two microRNAs (hbr-miR156, unconservative_Chr03_contig343_2364) as the candidate for leaf traits. Those findings will provide important genomic resources for cotton leaf improvement breeding.

Transcriptomic and metabolomic profiling of flavonoid biosynthesis provides novel insights into petals coloration in Asian cotton (Gossypium arboreum L.).

BACKGROUND: Asian cotton (Gossypium arboreum L.), as a precious germplasm resource of cotton with insect resistance and stress tolerance, possesses a broad spectrum of phenotypic variation related to pigmentation. Flower color affects insect pollination and the ornamental value of plants. Studying flower color of Asian cotton varieties improves the rate of hybridization and thus enriches the diversity of germplasm resources. Meanwhile, it also impacts the development of the horticultural industry. Unfortunately, there is a clear lack of studies concerning intricate mechanisms of cotton flower-color differentiation. Hereby, we report an integrative approach utilizing transcriptome and metabolome concerning flower color variation in three Gossypium arboreum cultivars. RESULTS: A total of 215 differentially accumulated metabolites (DAMs) were identified, including 83 differentially accumulated flavonoids (DAFs). Colorless kaempferol was more abundant in white flowers, while gossypetin-fer showed specificity in white flowers. Quercetin and gossypetin were the main contributors to yellow petal formation. Pelargonidin 3-O-beta-D-glucoside and cyanidin-3-O-(6''-Malonylglucoside) showed high accumulation levels in purple petals. Quercetin and gossypetin pigments also promoted purple flower coloration. Moreover, 8178 differentially expressed genes (DEGs) were identified by RNA sequencing. The correlation results between total anthocyanins and DEGs were explored, indicating that 10 key structural genes and 29 transcription factors promoted anthocyanin biosynthesis and could be candidates for anthocyanin accumulation. Ultimately, we constructed co-expression networks of key DAFs and DEGs and demonstrated the interactions between specific metabolites and transcripts in different color flowers. CONCLUSION: This study provides new insights into elucidating the regulatory mechanisms of cotton flower color and lays a potential foundation for generate cotton varieties with highly attractive flowers for pollinators.

Genome-wide association study for seedling biomass-related traits in Gossypium arboreum L.

BACKGROUND: Seedling stage plant biomass is usually used as an auxiliary trait to study plant growth and development or stress adversities. However, few molecular markers and candidate genes of seedling biomass-related traits were found in cotton. RESULT: Here, we collected 215 Gossypium arboreum accessions, and investigated 11 seedling biomass-related traits including the fresh weight, dry weight, water content, and root shoot ratio. A genome-wide association study (GWAS) utilizing 142,5003 high-quality SNPs identified 83 significant associations and 69 putative candidate genes. Furthermore, the transcriptome profile of the candidate genes emphasized higher expression of Ga03G1298, Ga09G2054, Ga10G1342, Ga11G0096, and Ga11G2490 in four representative cotton accessions. The relative expression levels of those five genes were further verified by qRT-PCR. CONCLUSIONS: The significant SNPs, candidate genes identified in this study are expected to lay a foundation for studying the molecular mechanism for early biomass development and related traits in Asian cotton.

Synthesis, Crystal Growth, and Annealing of CdSxSe1-x and Cr:CdS0.8Se0.2 Single Crystals.

Mid-infrared laser in the 2-5 µm wavelength region is in the atmospheric transmission window range, and hence, it has important application prospects in the fields of optoelectronic countermeasures, space communication, environmental remote sensing, and molecular spectroscopy. One of the most promising technological approaches to achieve mid-infrared laser output is based on direct lasing of transition-metal (TM)-doped II-VI chalcogenide crystals. In this work, CdSxSe1-x and Cr:CdS0.8Se0.2 polycrystals were synthesized by a chemical vapor synthesis method from a stoichiometric mixture of vacuum-sublimed CdS and CdSe. The structure of the synthesized products was analyzed by X-ray diffraction (XRD). Using these synthesized products, CdSxSe1-x and Cr:CdS0.8Se0.2 single crystals were grown by the physical vapor transport (PVT) method. After annealing, the band gap becomes smaller and the transmission range widens to 17 µm. The composition of the single crystals was determined by energy-dispersive spectrometry (EDS) mapping and XPS, and it was found to be uniform throughout the ingot. In addition, the absorption peak maximum for the Cr2+ ion in the Cr:CdS0.8Se0.2 crystal is at 1.84 µm.

Crystal Growth, Characterization, and Thermal Annealing of Nonlinear Optical Crystals AgGaGenSe2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) for Mid-infrared Applications.

The new quaternary single crystals AgGaGenSe2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) have high nonlinear optical property and can be used for mid-IR laser applications in high power. However, only AgGaGe3Se8 and AgGaGe5Se12 have been grown on a large scale and studied in detail. In this work, the AgGaGenSe2(n+1) (n = 1.5, 1.75, 2, 3, 4, 5, and 9) crystals (Φ 20 mm × 40 mm and Φ 40 mm × 100 mm) were grown by the modified Bridgman method. The crystal structure was studied by X-ray diffraction and the Rietveld refinement method. The composition and morphology were characterized by scanning electron microscopy and metallurgical microscopy. The chemical state and vibration modes of surface elements were characterized by X-ray photoelectron spectroscopy and Raman spectra, and the electrical property was investigated by the Hall effect measurement, which indicates that all the single AgGaGenSe2(n+1) crystals are n-type semiconductors. The transmittance of all as-grown AgGaGenSe2(n+1) crystal wafers exceed 65% in the transparent range, and the band gap increases from 2.05 eV for AgGaGe1.5Se5 to 2.14 eV for AgGaGe9Se20. Besides, after being annealed in two different conditions, the wafers show different changes. We discovered a special decomposition phenomenon during the annealing process and found the more appropriate annealing method at last. In addition, the absorption peaks at 4.2, 10, and 14.9 µm of wafers have been nearly eliminated, and the quality of most crystals has been improved.

Surgical Management of 48 Patients with Retrosternal Goiter and Tracheal Stenosis: A Retrospective Clinical Study from a Single Surgical Center.

BACKGROUND Benign retrosternal thyroid goiters can become large enough to compress the trachea and result in tracheomalacia and stenosis. This retrospective study from a single surgical center aimed to study the surgical management of 48 patients with retrosternal goiter and tracheal stenosis diagnosed and treated from January 2017 to December 2021. MATERIAL AND METHODS All preoperative contrast-enhanced CT scans showed retrosternal goiter and tracheal stenosis. RG was classified into type I in 28 patients, type II in 12 patients, and type III in 8 patients. TS was classified into grade I in 31 patients, grade II in 11 patients, and grade III in 6 patients. All patients were referred for surgery. Clinicopathologic features and surgical outcomes were recorded. RESULTS All operations were successfully performed. There were 41 patients with transcervical incision, 4 with cervical incision+sternotomy, 2 with cervical incision and thoracoscopic surgery, and 1 with cervical incision and surgery via the subxiphoid approach. Two patients presented recurrent laryngeal nerve injury. One patient showed short-term hand and foot numbness. The patients were pathologically diagnosed as simple nodular goiter (n=27), nodular goiter combined with cystic change (n=6), adenomatous nodular goiter (n=10), and thyroid adenoma (n=5). There was no prominent tumor recurrence or gradual TS remission. CONCLUSIONS This study has highlighted that patients with retrosternal goiter and tracheal stenosis may have comorbidities and require a multidisciplinary approach to management. The choice of anesthesia, surgical approach, and maintenance of the airway during and after surgery should be individualized.

Identification, characterization and expression profiling of circular RNAs in the early cotton fiber developmental stages.

Circular RNA is one of the endogenous non-coding RNAs with a covalently closed loop structure and largely involved in regulating gene expression. However, the abundance of circular RNAs and their regulatory functions during the early stages of fiber development are still not known. In this work, we conducted high-throughput sequencing of the Ligonlintless-1 and its wild-type at 0 DPA, 8 DPA and stem. A total of 2811 circular RNAs were identified and unevenly distributed across cotton chromosomes. We found 34, 142 and 27 circular RNAs were differentially expressed between Ligonlintless-1 and wild-type at 0 DPA, 8 DPA and stem, respectively. Both circular RNA-microRNA-mRNA network and MeJA treatment results in Ligonlintless-1 and wild-type might provide a strong indication of four circular RNAs and ghr_miR169b being important biological molecular associating with fiber development. The results provide new insight into the putative molecular function of circular RNAs in the regulation of fiber development.

GhGASA10-1 promotes the cell elongation in fiber development through the phytohormones IAA-induced.

BACKGROUND: Cotton is an important cash crop. The fiber length has always been a hot spot, but multi-factor control of fiber quality makes it complex to understand its genetic basis. Previous reports suggested that OsGASR9 promotes germination, width, and thickness by GAs in rice, while the overexpression of AtGASA10 leads to reduced silique length, which is likely to reduce cell wall expansion. Therefore, this study aimed to explore the function of GhGASA10 in cotton fibers development. RESULTS: To explore the molecular mechanisms underlying fiber elongation regulation concerning GhGASA10-1, we revealed an evolutionary basis, gene structure, and expression. Our results emphasized the conservative nature of GASA family with its origin in lower fern plants S. moellendorffii. GhGASA10-1 was localized in the cell membrane, which may synthesize and transport secreted proteins to the cell wall. Besides, GhGASA10-1 promoted seedling germination and root extension in transgenic Arabidopsis, indicating that GhGASA10-1 promotes cell elongation. Interestingly, GhGASA10-1 was upregulated by IAA at fiber elongation stages. CONCLUSION: We propose that GhGASA10-1 may promote fiber elongation by regulating the synthesis of cellulose induced by IAA, to lay the foundation for future research on the regulation networks of GASA10-1 in cotton fiber development.

Large-fragment insertion activates gene GaFZ (Ga08G0121) and is associated with the fuzz and trichome reduction in cotton (Gossypium arboreum).

Cotton seeds are typically covered by lint and fuzz fibres. Natural 'fuzzless' mutants are an ideal model system for identifying genes that regulate cell initiation and elongation. Here, using a genome-wide association study (GWAS), we identified a ~ 6.2 kb insertion, larINDELFZ , located at the end of chromosome 8, composed of a ~ 5.0 kb repetitive sequence and a ~ 1.2 kb fragment translocated from chromosome 12 in fuzzless Gossypium arboreum. The presence of larINDELFZ was associated with a fuzzless seed and reduced trichome phenotypes in G. arboreum. This distant insertion was predicted to be an enhancer, located ~ 18 kb upstream of the dominant-repressor GaFZ (Ga08G0121). Ectopic overexpression of GaFZ in Arabidopsis thaliana and G. hirsutum suggested that GaFZ negatively modulates fuzz and trichome development. Co-expression and interaction analyses demonstrated that GaFZ might impact fuzz fibre/trichome development by repressing the expression of genes in the very-long-chain fatty acid elongation pathway. Thus, we identified a novel regulator of fibre/trichome development while providing insights into the importance of noncoding sequences in cotton.

A copy number variant at the HPDA-D12 locus confers compact plant architecture in cotton.

Improving yield is a primary mission for cotton (Gossypium hirsutum) breeders; development of cultivars with suitable architecture for high planting density (HPDA) can increase yield per unit area. We characterized a natural cotton mutant, AiSheng98 (AS98), which exhibits shorter height, shorter branch length, and more acute branch angle than wild-type. A copy number variant at the HPDA locus on Chromosome D12 (HPDA-D12), encoding a dehydration-responsive element-binding (DREB) transcription factor, GhDREB1B, strongly affects plant architecture in the AS98 mutant. We found an association between a tandem duplication of a c. 13.5 kb segment in HPDA-D12 and elevated GhDREB1B expression resulting in the AS98 mutant phenotype. GhDREB1B overexpression confers a significant decrease in plant height and branch length, and reduced branch angle. Our results suggest that fine-tuning GhDREB1B expression may be a viable engineering strategy for modification of plant architecture favorable to high planting density in cotton.

Revascularization of Coronary Artery Chronic Total Occlusion by Active Antegrade Reverse Wire Technique.

OBJECTIVES: To assess the effectiveness and safety of ARW for vascular recanalization in CTO patients. BACKGROUND: Chronic total occlusion (CTO) of coronary artery accompanied with large branch distal to the occluded segment (<2 mm) is one of the challenges physicians are facing during the coronary intervention. In cases where the antegrade wire passed the occluded segment reaching the branch vessel, but could not access the main vessel through various adjustments, application of active antegrade reverse wire technique (ARW) could be considered. Patients and Methods. A total of 301 consecutive CTO patients who received the antegrade percutaneous coronary intervention (PCI) between December 2015 and December 2019 at our institution were included, of whom 11 were treated with ARW (10 successfully) for vascular recanalization. The applicability and safety of ARW were assessed. RESULTS: Among the 301 CTO patients who received antegrade vascular recanalization, 11 were treated with ARW. ARW was successful in 10 patients as follows: from the diagonal branch (D) to anterior descending branch (LAD) in 4 patients; from the septal branch (S) to LAD in 1 patient; from D to S and LAD in 1 patient; from the circumflex branch (LCX) to obtuse marginal branch (OM) in 1 patient; from OM to LCX in 1 patient; from a posterior descending artery (PDA) to the posterior lateral vein (PLV) in 2 patients. Yet, ARW in patient with RCAm CTO failed, while the consequent retrograde PCI succeeded. The mean J-CTO score of the 11 patients was 2.7 ± 0.65, among whom eight were accompanied with calcifications. Sion Black and Fielder XTR reverse wires were used in 9 and 2 patients, respectively. No loss of side branches or severe procedure-related complications occurred in 11 patients. CONCLUSION: Therefore, ARW can improve procedural efficiency and should be popularized for further application.

Investigation of the Anisotropic Thermal Expansion Mechanism of AgxGaxGe1-xSe2 Crystals.

Quaternary nonlinear optical single crystals AgxGaxGe1-xSe2 (x = 0.250, 0.167) were grown by the Bridgman method in a four-zone furnace. The thermal expansion behavior of AgxGaxGe1-xSe2 (x = 0.25, 0.167) was studied by the method of single-crystal X-ray diffraction from 150 to 295 K and powder X-ray diffraction in the range of 298-773 K. Both results show the crystals have positive linear thermal expansion coefficients in different directions and a positive volume thermal expansion coefficient, and it is observed that they satisfy the relationship of αa > αc > αb and αV ≈ αa + αb + αc for the orthorhombic structure. It is found that the AgxGaxGe1-xSe2 (x = 0.25, 0.167) unit cells varying with temperature were mainly dominated by variations in framework geometry (AgSe4 tetrahedron), and the thermal motion of Ag atoms in the AgSe4 tetrahedron. As it was revealed, according to the powder X-ray diffraction, it is found that the isotropic thermal atomic displacement parameter of the Ag atoms is much larger than those of the Se and Ga(Ge) atoms in the AgSe4 tetrahedron. Furthermore, anisotropic atomic displacement parameters (ADPs) of Ag atoms are extracted from the single-crystal diffraction; the ADPs along the a axis, b axis, and c axis have a significant difference, which means the thermal vibration of Ag atoms is anisotropic. It is of great significance for improving crystal growth technology and understanding the thermal properties of this kind of crystals.

Improving postural stability among people with lower-limb amputations by tactile sensory substitution.

BACKGROUND: For people with lower-limb amputations, wearing a prosthetic limb helps restore their motor abilities for daily activities. However, the prosthesis's potential benefits are hindered by limited somatosensory feedback from the affected limb and its prosthesis. Previous studies have examined various sensory substitution systems to alleviate this problem; the prominent approach is to convert foot-ground interaction to tactile stimulations. However, positive outcomes for improving their postural stability are still rare. We hypothesized that the sensory substiution system based on surrogated tactile stimulus is capable of improving the standing stability among people with lower-limb amputations. METHODS: We designed a wearable device consisting of four pressure sensors and two vibrators and tested it among people with unilateral transtibial amputations (n = 7) and non-disabled participants (n = 8). The real-time measurements of foot pressure were fused into a single representation of foot-ground interaction force, which was encoded by varying vibration intensity of the two vibrators attached to the participants' forearm. The vibration intensity followed a logarithmic function of the force representation, in keeping with principles of tactile psychophysics. The participants were tested with a classical postural stability task in which visual disturbances perturbed their quiet standing. RESULTS: With a brief familiarization of the system, the participants exhibited better postural stability against visual disturbances when switching on sensory substitution than without. The body sway was substantially reduced, as shown in head movements and excursions of the center of pressure. The improvement was present for both groups of participants and was particularly pronounced in more challenging conditions with larger visual disturbances. CONCLUSIONS: Substituting otherwise missing foot pressure feedback with vibrotactile signals can improve postural stability for people with lower-limb amputations. The design of the mapping between the foot-ground interaction force and the tactile signals is essential for the user to utilize the surrogated tactile signals for postural control, especially for situations that their postural control is challenged.