Modulating the Structure and Optoelectronic Properties of Solution-Processed Bismuth-Based Nanocrystals.

Bismuth-based chalcogenides have emerged as promising candidates for next-generation, solution-processable semiconductors, mainly benefiting from their facile fabrication, low cost, excellent stability, and tunable optoelectronic properties. Particularly, the recently developed AgBiS2 solar cells have shown striking power conversion efficiencies. High performance bismuth-based photodetectors have also been extensively studied in the past few years. However, the fundamental properties of these Bi-based semiconductors have not been sufficiently investigated, which is crucial for further improving the device performance. Here, we introduce multiple time-resolved and steady-state techniques to fully characterize the charge carrier dynamics and charge transport of solution-processed Bi-based nanocrystals. It was found that the Ag-Bi ratio plays a critical role in charge transport. For Ag-deficient samples, silver bismuth sulfide thin films behave as localized state induced hopping charge transport, and the Ag-excess samples present band-like charge transport. This finding is crucial for developing more efficient Bi-based semiconductors and optoelectronic devices.

[Colon adenoma detection using Kubelka-Munk spectral function of DNA and protein bands].

Differential diagnosis of human colon adenoma was studied using the Kubelka-Munk spectral function of the DNA and protein absorption bands at 260 and 280 nm in vitro. Diffuse reflectance spectra of tissue were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that for the spectral range from 590 to 1 064 nm pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the DNA absorption bands at 260 nm between normal and adenomatous colon epithelial tissues, and the differences were 218% (p < 0.05) and 68.5% (p < 0.05) respectively. Pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the protein absorption bands at 280 nm between normal and adenomatous colon epithelial tissues, and the differences were 208% (p < 0.05) and 59.0% (p < 0.05) respectively. Pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the beta-carotene absorption bands at 480 nm between normal and adenomatous colon epithelial tissues, and the differences were 41.7% (p < 0.05) and 32.9% (p < 0.05) respectively. Obviously, pathological changes of colon epithelial tissues were induced so that there were significant changes in the contents of the DNA, protein and beta-carotene of colon epithelial tissues. The conclusion can be applied to rapid, low-cost and noninvasive optical biopsy of colon adenoma, and provides a useful reference.

[Superficial bladder cancer detection using diffuse reflectance spectral ratio R540/R575 of oxygenated hemoglobin bands].

A low-cost, fast, and noninvasive method for early diagnosis of malignant lesions of mucosa tissue based on diffuse reflectance spectra was applied in the study of the optical biopsy of superficial human bladder cancer. In the present paper, differential diagnosis of superficial human bladder cancer was studied using the diffuse reflectance spectral ratio (R540/R575) of the oxygenated hemoglobin absorption bands at 540 and 575 nm in vitro. Diffuse reflectance spectra for mucosa/submucosa tissues of normal bladder and superficial bladder cancer were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that there were three the diffuse reflectance spectral dips at 415, 542 and 577 nm respectively for mucosa/submucosa tissues of normal bladder and superficial bladder cancer in the spectral range from 400 to 600 nm. The mean diffuse reflectance spectral ratio (R540/R575) of normal bladder mucosa/submucosa tissue decreased slowly with time increase after surgical excision, and the mean diffuse reflectance spectral ratio (R540/R575) of superficial bladder cancer mucosa/ submucosa tissue also decreased slowly with time increasing after surgical excision. The mean diffuse reflectance spectral ratios (R540/R575) of normal bladder mucosa/submucosa tissue were 111%, 107%, 104% and 102% after 2, 3, 4 and 5 h after surgical excision respectively, and those of superficial bladder cancer mucosa/submucosa tissue were 98.4%, 95.5%, 93.1% and 91.6% after 2, 3, 4 and 5 h after surgical excision respectively. There were significant differences in mean diffuse reflectance spectral ratio (R540/R575) for mucosa/submucosa tissues between normal bladder and superficial bladder cancer after 2, 3, 4 and 5 h after surgical excision respectively (p < 0.05). Differences in mean diffuse reflectance spectral ratio (R540/R575) for mucosa/ submucosa tissues between normal bladder and superficial bladder cancer were 12.6%, 11.5%, 10.9% and 10.4% after 2, 3, 4 and 5 h after surgical excision respectively. It is obvious that pathological changes in bladder mucosa/submucosa tissues induced changes in the component and structure of the tissues, and especially quantitative changes in oxyhemoglobin and de-oxyhemoglobin of tissues obviously. Conclusion of the study provides a new method that can be applied to rapid, low-cost and noninvasive optical biopsy of superficial bladder cancer.

[Thermal coagulation of human benign prostatic hyperplasia tissues induced changes in the absorption and scattering properties in spectral range from 590 to 1 064 nm in vitro].

The optical properties and their differences of native and coagulated human benign prostatic hyperplasia (BPH) tissues were studied in the spectral range from 590 to 1 064 nm in vitro. The measurements were performed using a spectrophotometer with an integrating sphere attachment, and the absorption and scattering properties were assessed from these measurements using the inverse adding-doubling method. The results of measurement showed that the thermal coagulation of BPH tissues induced obviously the decrease in the absorption coefficients in the spectral range from 590 to 1 064 nm. The peaks in the absorption coefficients for native and coagulated BPH tissues were respectively 0.438 and 0.416 mm(-1) corresponding to the same wavelength of 990 nm, the maximum difference in the absorption coefficients of native and coagulated BPH tissues is 86.79% at 1 064 nm, and the minimum difference is 4.74% at 920 nm. The thermal coagulation of BPH tissues induced an increase in the reduced scattering coefficients in the spectral range from 600 to 1 064 nm obviously, and induced a decrease in the reduced scattering coefficients at 590 nm obviously. The peaks in the reduced scattering coefficients for native and coagulated BPH tissues were respectively 1.090 and 1. 449 mm(-1) corresponding to the same wavelength of 970 nm, and other peaks in the reduced scattering coefficients for native and coagulated BPH tissues were respectively 1.116 and 1.627 mm(-1) corresponding to the same wavelength of 1 050 nm, the maximum difference in the reduced scattering coefficients of native and coagulated BPH tissues is 47.73% at 1 064 nm, and the minimum difference is 4.86% at 600 nm.

[Absorption and scattering characteristics of human benign prostatic hyperplasia tissue with Ti: sapphire laser irradiation in vitro].

The optical properties and their differences of human benign prostatic hyperplasia (BPH) tissues removed using transurethral plasma kinetic resection of the prostate (PKRP) and transurethral vaporization of the prostate (TUVP) at 640, 660, 680, 700, 720, 740, 760, 780, 800, 820, 840, 860 and 880 nm of Ti: Sapphire laser were studied in vitro. The measurements were performed using a double-integrating-sphere setup, and the absorption and scattering properties were assessed using the inverse adding-doubling method. The results of measurement showed that the absorption coefficients and reduced scattering coefficients of BPH tissues removed using PKRP and TURP obviously decreased with the increase in the wavelength for thirteen different laser wavelengths. The absorption coefficient and reduced scattering coefficient of BPH tissues removed using PKRP at a certain laser wavelength were obviously smaller than that of BPH tissues removed using TUVP at the same laser wavelength. The maximum absorption coefficient and maximum reduced scattering coefficient of BPH tissues removed using PKRP and TURP were respectively (0. 885 +/- 0. 022) and (0.955 +/- 0.024)mm(-1), and (1.564 +/- 0.039) and (1.658 +/- 0.042)mm(-1) at 640 nm, their differences were respectively 7.91% and 6.01%, and the minimum absorption coefficient and minimum reduced scattering coefficient of BPH tissues removed using PKRP and TURP were respectively (0.443 +/- 0.011) and (0.455 +/- 0.011) mm(-1), and (1.117 +/- 0.028) and (1.197 +/- 0.030)mm(-1) at 640 nm, their differences were respectively 2.71% and 9.13%. The maximum difference in the absorption coefficients of BPH tissues removed using PKRP and TURP is 8.95% at 660 nm, and the minimum difference is 1.75% at 860 nm. The maximum difference in the reduced scattering coefficients of BPH tissues removed using PKRP and TURP is 9.13% at 800 nm, and the minimum difference is 6.01% at 640 nm.

[Canceration and thermal coagulation of human liver induced changes in the absorption and scattering properties of liver-tissue at near infrared in vitro].

Canceration and thermal coagulation of human liver induced changes in the absorption and scattering properties of liver tissue at 710, 730, 750, 77, 790, 810, 830, 850, 870 and 890 nm of Ti: sapphire laser were studied in vitro. The measurements were performed using a double-integrating-sphere setup, and the absorption and scattering properties were assessed from these measurements using the inverse adding-doubling method. The results of measurement showed that canceration of liver induced significant decrease in the absorption coefficients of liver tissue, and the maximum change in the absorption coefficients is 86.12% at 850 nm, while the minimum change in the absorption coefficients is 82.65% at 750 nm. Thermal coagulation of normal liver induced obvious change in the absorption coefficients from 710 to 890 nm, and the maximum change in the absorption coefficients is 79.55% at 710 nm, while the minimum change in the absorption coefficients 0.72% at 790 nm. Thermal coagulation of carcinoma liver tissue induced significant increase in the absorption coefficients, the maximum change in the absorption coefficients of carcinoma liver tissue is 78.69% at 810 nm, in the minimum change in the absorption coefficients of carcinoma liver tissue 38.16% at 710 nm. Canceration of liver induced significant increase in the scattering coefficients of liver tissue, and the maximum change in the scattering coefficients is 158.37% at 710 nm, while the minimum change in the scattering coefficients is 136.03% at 890 nm. Thermal coagulation of normal liver induced significant increase in the scattering coefficients of liver tissue, and the maximum change in the scattering coefficients is 632.92% at 890 nm, while the minimum change for the scattering coefficients is 587.40% at 710 nm. Thermal coagulation of carcinoma liver tissue induced significant increase in the scattering coefficients, and the maximum change in the scattering coefficients of carcinoma liver tissue is 384. 25% at 810 nm, while the minimum change in the scattering coefficients of carcinoma liver tissue is 330. 86% at 710 nm. The change in the absorption and scattering properties also varies with the change of laser wavelength.

[Comparison of light attenuation characteristics and optical penetration depths between native and coagulated human liver tissues].

A double-integrating-spheres and IAD method were used to study the differences in the optical penetration depths (OPDs) and light attenuation (LA) native and coagulated human liver tumors and liver tissues at the wavelengths of 680, 720, 780, 810, 850 and 890 nm of Ti: Sapphire laser. The results of measurement showed that the OPDs for native and coagulated human liver tumors and liver tissues at six different wavelengths obviously increase with increasing laser wavelength, the OPDs of coagulated human liver tumors and liver tissues at six different wavelengths were significantly smaller than that of native human liver tumors and liver tissues at the same wavelength respectively (P<0.05), and the OPDs of native and coagulated human liver tumors at six different wavelengths were significantly bigger than that of native and coagulated human liver tissues at the same wavelength respectively (P<0.05). The LA for native and coagulated human liver tumors and liver tissues at six different wavelengths obviously decreases with increasing laser wavelength, and the LA for coagulated human liver tumors and liver tissues at six different wavelengths is significantly bigger than that for native human liver tumors and liver tissues at the same wavelength respectively (P<0.05). The LA for native and coagulated human liver tumors at six different wavelengths is significantly bigger than that for native and coagulated human liver tissue at the same wavelength respectively (P<0.05).