An innovation technology for recovering silver and valuable metals from hazardous zinc leaching residue through direct reduction

Zinc leaching residue (ZLR) is a hazardous solid waste with complex phase composition, comprising high content of valuable metals, and sulfur. The extraction of silver is the key to harmless utilization of ZLR. In this paper, a short-flowsheet comprehensive recycling valuable metals method by direct reduction was proposed. During reduction, lead and zinc compounds were reduced to metallic state, which were volatilized and recovered in gas phase. Moreover, metallic iron in reduction product was recovered by magnetic separation. Silver was enriched in FeS phase, and it was beneficiated by flotation with hydrophobic FeS as carrier. Under the optimized conditions, silver concentrate with silver content and recovery of 601.43 g/t and 83.41 %, respectively; iron powder with iron content of 96.39 %; and lead and zinc volatilization rate of 78.65 % and 97.64 %, respectively, were obtained. Toxicity characteristic leaching procedure (TCLP) results indicated that tailings were harmless. The mechanisms were subsequently investigated by combining thermodynamics analyses and systematic characterizations. Especially, a one-step containing two-stage capture silver mechanism was ascertained in reduction with sulfur: formation of silver-lead alloys, and encapsulation of silver-lead alloys by FeS phase to decrease symbiotic relationship between valuable metals and slag. This entire recycling process can provide ideas for harmless recovering precious metals from hazardous waste

Exploring the effect of hypertension on retinal microvasculature using deep learning on East Asian population.

Hypertension is the leading risk factor of cardiovascular disease and has profound effects on both the structure and function of the microvasculature. Abnormalities of the retinal vasculature may reflect the degree of microvascular damage due to hypertension, and these changes can be detected with fundus photographs. This study aimed to use deep learning technique that can detect subclinical features appearing below the threshold of a human observer to explore the effect of hypertension on morphological features of retinal microvasculature. We collected 2012 retinal photographs which included 1007 from patients with a diagnosis of hypertension and 1005 from normotensive control. By method of vessel segmentation, we removed interference information other than retinal vasculature and contained only morphological information about blood vessels. Using these segmented images, we trained a small convolutional neural networks (CNN) classification model and used a deep learning technique called Gradient-weighted Class Activation Mapping (Grad-CAM) to generate heat maps for the class "hypertension". Our model achieved an accuracy of 60.94%, a specificity of 51.54%, a precision of 59.27%, and a recall of 70.48%. The AUC was 0.6506. In the heat maps for the class "hypertension", red patchy areas were mainly distributed on or around arterial/venous bifurcations. This indicated that the model has identified these regions as being the most important for predicting hypertension. Our study suggested that the effect of hypertension on retinal microvascular morphology mainly occurred at branching of vessels. The change of the branching pattern of retinal vessels was probably the most significant in response to elevated blood pressure

An innovation technology for recovering silver and valuable metals from hazardous zinc leaching residue through direct reduction

Zinc leaching residue (ZLR) is a hazardous solid waste with complex phase composition, comprising high content of valuable metals, and sulfur. The extraction of silver is the key to harmless utilization of ZLR. In this paper, a short-flowsheet comprehensive recycling valuable metals method by direct reduction was proposed. During reduction, lead and zinc compounds were reduced to metallic state, which were volatilized and recovered in gas phase. Moreover, metallic iron in reduction product was recovered by magnetic separation. Silver was enriched in FeS phase, and it was beneficiated by flotation with hydrophobic FeS as carrier. Under the optimized conditions, silver concentrate with silver content and recovery of 601.43 g/t and 83.41 %, respectively; iron powder with iron content of 96.39 %; and lead and zinc volatilization rate of 78.65 % and 97.64 %, respectively, were obtained. Toxicity characteristic leaching procedure (TCLP) results indicated that tailings were harmless. The mechanisms were subsequently investigated by combining thermodynamics analyses and systematic characterizations. Especially, a one-step containing two-stage capture silver mechanism was ascertained in reduction with sulfur: formation of silver-lead alloys, and encapsulation of silver-lead alloys by FeS phase to decrease symbiotic relationship between valuable metals and slag. This entire recycling process can provide ideas for harmless recovering precious metals from hazardous waste

Accuracy of intraocular lens calculation formulas in cataract patients with steep corneal curvature.

ObjectiveTo compare the accuracy of five kinds of intraocular lens calculation formulas (SRK/T, Haigis, Hoffer Q, Holladay and Barrett Universal Ⅱ) in cataract patients with steep curvature cornea ≥ 46.0 diopters.MethodsThis is a retrospective study of cataract phacoemulsification combined with intraocular lens implantation in patients with steep curvature cornea (corneal curvature ≥ 46D). The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Objective refraction results were assessed at one month postoperatively. According to axial length (AL), all patients were divided into three groups: short AL group (22 to ≤24.5mm) and long AL group (>24.5mm). Calculate the refractive error and absolute refractive error (AE) between the actual postoperative refractive power and the predicted postoperative refractive power. The covariance analysis was used for the comparison of five formulas in each group. The correlation between the absolute refractive error and AL from every formula were analyzed by Pearson correlation test, respectively.ResultTotal 112 eyes of 83 cataract patients with steep curvature cornea were collected. The anterior chamber depth (ACD) was a covariate in the short AL group in the covariance analysis of absolute refractive error (PConclusionCompared to SRK/T, Haigis, Hoffer Q, and Holladay, Barrett Universal Ⅱ formula is more accurate in predicting the IOL power in the cataract patients with steep curvature cornea ≥ 46.0 diopters

Crystal Structure of a Thermostable Alanine Racemase from <i>Thermoanaerobacter tengcongensis</i> MB4 Reveals the Role of Gln360 in Substrate Selection

<div><p>Pyridoxal 5’-phosphate (PLP) dependent alanine racemase catalyzes racemization of L-Ala to D-Ala, a key component of the peptidoglycan network in bacterial cell wall. It has been extensively studied as an important antimicrobial drug target due to its restriction in eukaryotes. However, many marketed alanine racemase inhibitors also act on eukaryotic PLP-dependent enzymes and cause side effects. A thermostable alanine racemase (Alr_Tt) from <i>Thermoanaerobacter tengcongensis</i> MB4 contains an evolutionarily non-conserved residue Gln360 in inner layer of the substrate entryway, which is supposed to be a key determinant in substrate specificity. Here we determined the crystal structure of Alr_Tt in complex with L-Ala at 2.7 Å resolution, and investigated the role of Gln360 by saturation mutagenesis and kinetic analysis. Compared to typical bacterial alanine racemase, presence of Gln360 and conformational changes of active site residues disrupted the hydrogen bonding interactions necessary for proper PLP immobilization, and decreased both the substrate affinity and turnover number of Alr_Tt. However, it could be complemented by introduction of hydrophobic amino acids at Gln360, through steric blocking and interactions with a hydrophobic patch near active site pocket. These observations explained the low racemase activity of Alr_Tt, revealed the essential role of Gln360 in substrate selection, and its preference for hydrophobic amino acids especially Tyr in bacterial alanine racemization. Our work will contribute new insights into the alanine racemization mechanism for antimicrobial drug development.</p></div

Adjuvant and salvage radiotherapy after prostatectomy: a systematic review and meta-analysis.

In men with adverse prognostic factors (APFs) after radical prostatectomy (RP), the most appropriate timing to administer radiotherapy remains a subject for debate. We conducted a systemic review and meta-analysis to evaluate the therapeutic strategies: adjuvant radiotherapy (ART) and salvage radiotherapy (SRT).We comprehensively searched PubMed, EMBASE, Web of Science and the Cochrane Library and performed the meta-analysis of all randomized controlled trials (RCTs) and retrospective comparative studies assessing the prognostic factors of ART and SRT.Between May 1998 and July 2012, 2 matched control studies and 16 retrospective studies including a total of 2629 cases were identified (1404 cases for ART and 1185 cases for SRT). 5-year biochemical failure free survival (BFFS) for ART was longer than that for SRT (Hazard Ratio [HR]: 0.37; 95% CI, 0.30-0.46; p<0.00001, I(2) = 0%). 3-year BFFS was significantly longer in the ART (HR: 0.38; 95% CI, 0.28-0.52; p<0.00001, I(2) = 0%). Overall survival (OS) was also better in the ART (RR: 0.53; 95% CI, 0.41-0.68; p<0.00001, I(2) = 0%), as did disease free survival (DFS) (RR: 0.53; 95% CI, 0.43-0.66; p<0.00001, I(2)  = 0%). Exploratory subgroup analysis and sensitivity analysis revealed the similar results with original analysis.ART therapy offers a safe and efficient alternative to SRT with longer 3-year and 5-year BFFS, better OS and DFS. Our recommendation is to suggest ART for patients with APFs and may reduce the need for SRT. Given the inherent limitations of the included studies, future well-designed RCTs are awaited to confirm and update this analysis

Ground Surface Temperature History Since the Last Glacial Maximum in Northeast Asia: Reconstructions From the Borehole Geotherms of the International Continental Scientific Drilling Program

Abstract Past ground surface temperature (GST), one of the important aspects of paleoclimate reconstructions, can be inverted from borehole temperature measurements. Here, we report continuous 6,100‐m temperature logs in the International Continental Scientific Drilling Program SK‐2e. We inverted the past GST changes from upper borehole temperature logging (<600 m). Below this depth, localized fluid flow masks the paleoclimate record. Inversions yield an approximately 2 K GST rise since 0.1–0.6 Kyr BP and an approximately 10 K rise since 20 Kyr BP. Assuming a ±5 K influence from the deep groundwater flow, the inverted temperature rise has varied between 8 and 12 K since 20 Kyr BP, which is consistent with previous reports since the Last Glacial Maximum. Our results emphasize the potential of borehole heat‐flow profiles as a record of climate changes and the importance of climate correction for heat‐flow determinations

Structural based sequence alignment of Alr_<i>Tt</i>, DadX_<i>Tt</i> and other three representative bacterial alanine racemases.

<p>Amino acid sequences of alanine racemase from a gram positive bacteria <i>Bacillus stearothermophilus</i> (Alr_<i>Bst</i>), a gram negative bacteria <i>Pseudomonas aeruginosa</i> (DadX_<i>pao</i>), and <i>Clostridium difficile</i> strain 630 (Alr_<i>Cd</i>) are aligned with Alr_<i>Tt</i> and DadX_<i>Tt</i> from <i>T</i>. <i>tengcongensis</i> MB4. Amino acids are numbered and secondary structures are labeled, strictly conserved amino acids are highlighted in yellow box. Amino acids form the substrate entryway are colored in blue (middle layer) and magenta (inner layer), key catalytic residues mediating the phosphate group and L-Ala binding are colored in red, residues necessary for hydrogen bonding interactions for PLP-binding are colored in green. Two key catalytic residues Lys40 and Tyr268’ are marked with a star. The hydrophobic patch (Pro225-Arg337) in Alr_<i>Tt</i> is indicated by a red box.</p

Comparison of the active site pocket of Alr_<i>Tt</i> with other three bacterial alanine racemases.

<p><b>(A)</b> The active site pocket of Alr_<i>Tt</i> (PDB 4Y2W), phosphate group, L-Ala and key amino acids that involved in substrate binding are shown in sticks, the hydrogen bonding interactions are indicated. Same view of the active site pocket of other three bacteria alanine racemase in complex with substrates are shown in same profile: <b>(B)</b> the PLP-D-Ala complex of Alr_<i>Bst</i> (PDB 1L6G), <b>(C)</b> PLP complex of Alr_<i>Cd</i> (PDB 4LUS), <b>(D)</b> PLP and DLY complex of DadX_<i>pao</i> (PDB 1RCQ).</p