Metallic transition metal dichalcogenides (TMDs)
are good catalysts for the hydrogen evolution reaction (HER). The overpotential and Tafel slope values of metallic phases and edges
of two-dimensional ...(2D) TMDs approach those of Pt. However, the overall current density of 2D TMD catalysts remains orders of magnitude lower (~10-100 mA cm
) than industrial Pt and Ir electrolysers (>1,000 mA cm
)
. Here, we report the synthesis of the metallic 2H phase of niobium disulfide with additional niobium (2H Nb
S
, where x is ~0.35)
as a HER catalyst with current densities of >5,000 mA cm
at ~420 mV versus a reversible hydrogen electrode. We find the exchange current density at 0 V for 2H Nb
S
to be ~0.8 mA cm
, corresponding to a turnover frequency of ~0.2 s
. We demonstrate an electrolyser based on a 2H Nb
S
cathode that can generate current densities of 1,000 mA cm
. Our theoretical results reveal that 2H Nb
S
with Nb-terminated surface has free energy for hydrogen adsorption that is close to thermoneutral, facilitating HER. Therefore, 2H Nb
S
could be a viable catalyst for practical electrolysers.
The excellent catalytic activity of metallic MoS2 edges for the hydrogen evolution reaction (HER) has led to substantial efforts towards increasing the edge concentration. The 2H basal plane is less ...active for the HER because it is less conducting and therefore possesses less efficient charge transfer kinetics. Here we show that the activity of the 2H basal planes of monolayer MoS2 nanosheets can be made comparable to state-of-the-art catalytic properties of metallic edges and the 1T phase by improving the electrical coupling between the substrate and the catalyst so that electron injection from the electrode and transport to the catalyst active site is facilitated. Phase-engineered low-resistance contacts on monolayer 2H-phase MoS2 basal plane lead to higher efficiency of charge injection in the nanosheets so that its intrinsic activity towards the HER can be measured. We demonstrate that onset potentials and Tafel slopes of ∼-0.1 V and ∼50 mV per decade can be achieved from 2H-phase catalysts where only the basal plane is exposed. We show that efficient charge injection and the presence of naturally occurring sulfur vacancies are responsible for the observed increase in catalytic activity of the 2H basal plane. Our results provide new insights into the role of contact resistance and charge transport on the performance of two-dimensional MoS2 nanosheet catalysts for the HER.
Two dimensional (2D) materials-based plasmon-free surface-enhanced Raman scattering (SERS) is an emerging field in nondestructive analysis. However, impeded by the low density of state (DOS), an ...inferior detection sensitivity is frequently encountered due to the low enhancement factor of most 2D materials. Metallic transition-metal dichalcogenides (TMDs) could be ideal plasmon-free SERS substrates because of their abundant DOS near the Fermi level. However, the absence of controllable synthesis of metallic 2D TMDs has hindered their study as SERS substrates. Here, we realize controllable synthesis of ultrathin metallic 2D niobium disulfide (NbS2) (<2.5 nm) with large domain size (>160 μm). We have explored the SERS performance of as-obtained NbS2, which shows a detection limit down to 10–14 mol·L–1. The enhancement mechanism was studied in depth by density functional theory, which suggested a strong correlation between the SERS performance and DOS near the Fermi level. NbS2 features the most abundant DOS and strongest binding energy with probe molecules as compared with other 2D materials such as graphene, 1T-phase MoS2, and 2H-phase MoS2. The large DOS increases the intermolecular charge transfer probability and thus induces prominent Raman enhancement. To extend the results to practical applications, the resulting NbS2-based plasmon-free SERS substrates were applied for distinguishing different types of red wines.
To evaluate the histopathologic correlation of recently described subclassification of Bosniak category 3 cysts (3s and 3n).
A total of 106 patients who underwent partial/radical nephrectomy due to a ...complex renal cyst (≥Bosniak 3) were retrospectively reviewed. All the scans of the patients were reevaluated by 2 experienced uroradiologists. Bosniak 3 cysts were reclassified as 3n (nodularity on the cyst wall/septae) and 3s (septated cysts without nodularity) as described in a recently published paper. Group 1 consisted of patients with Bosniak 3s, Group 2 consisted of patients with Bosniak 3n, and Group 3 consisted of patients with Bosniak 4 cysts. Three groups were compared according to patients' characteristics, radiological findings, histopathologic results, and survival outcomes.
There were 52 patients in Bosniak 3 group and 54 patients in Bosniak 4 group. Mean follow-up was 35.3 months. Among Bosniak 3 cysts, 37 lesions were classified in 3s and 15 were classified in 3n. Malignancy was higher in 3n group than 3s (86.7% vs 54.1%, P= .026). Lesion size was significantly lower for malignant cysts compared to benign ones in the patients with Bosniak 3 lesions (44.2 ± 27.5 vs 80 ± 55.9 P= .005). In the subgroups, malignant lesions were significantly smaller than benign lesions in 3s group similar to general Bosniak 3 group. Most of the Bosniak 3 lesions were organ confined and low grade.
The subclassification of Bosniak 3 cysts as 3s and 3n can help to differentiate highly suspicious malignant lesions from the relatively less suspicious ones.
ABSTRACT Purpose To evaluate the influence of preoperative renal function on survival outcomes in patients who underwent radical cystectomy (RC) with non-continent urinary diversion (UD). Materials ...and Methods A total of 132 patients with bladder cancer who underwent RC with non-continent UD due to urothelial carcinoma from January 2006 toMarch 2017 at our tertiary referral center were retrospectively evaluated. Patients were divided into 2 groups as those with estimated glomerular filtration rate (eGFR) <60mL/min/1.73 m2 and ≥60mL/min/1.73 m2 according to preoperative eGFR levels. Patients’ characteristics, preoperative clinical data, operative data, pathologic data, oncologic data and complications were compared between the groups. Results The mean age was 64.5±8.7 (range: 32 - 83) years and the median follow-up was 30.9±31.7 (range: 1-113) months. There were 46 patients in Group 1 and 86 patients in Group 2. There was no difference in cancer-specific mortality (45.6% for group 1 and 30.2% for group 2, p=0.078) and survival (56.8±8.3 months for group 1 and 70.5±5.9 months for group 2, p=0.087) between the groups. Overall mortality was higher (63% for group 1 and 40.7% for group 2, p=0.014) and overall survival (43.6±6.9 months for group 1 and 62.2±5.8 months for group 2, p=0.03) was lower in Group 1 compared to Group 2. Conclusions Overall mortality was higher and overall survival was lower in patients with preoperative eGFR <60mL/s. More patients had preoperative hydronephrosis with eGFR< 60mL/s.
Objectives
To externally validate and compare Resorlu‐Unsal stone score (RUSS), modified Seoul National University Renal Stone Complexity Score(S‐ReSC), Ito’s nomogram, and Retrograde Intra‐Renal ...Surgery (R.I.R.S.) scoring systems for predicting capabilities of both the stone‐free status and complications in a multi‐institutional study.
Materials and Methods
We performed a retrospective analysis of 949 patients who underwent flexible ureterorenoscopy (f‐URS) and laser lithotripsy for renal stones in two institutions between March‐2015 and June‐2020. The RUSS, modified S‐ReSC, Ito’s nomogram, and R.I.R.S. scores were calculated for each patient by the same surgeon on imaging methods. Results were compared for their predictive capability of stone‐free status and complications.
Results
Of 949 patients 603 were male and 346 were female with a mean age of 47.2 ± 14.3 (range 2‐84 years). Mean stone burden was 102.6 ± 42.2 (48‐270 mm2). All nomograms predicted stone‐free status (Area Under Curve (AUC) were 0.689, 0.657, 0.303, and 0.690, respectively). All four scoring systems predicted complications with AUC values of 0.689, 0.646, 0.286, and 0.664 for RUSS, modified S‐ReSC, Ito’s nomogram, and R.I.R.S., respectively. Although all scoring systems were able to predict complications only Ito’s nomogram was able to predict Clavien ≥2 complications.
Conclusion
All four scoring systems (RUSS, modified S‐ReSC, Ito’s nomogram, and R.I.R.S.) could predict stone‐free status after f‐URS, however, the AUC values are not satisfactory in our large patient cohort. Although these scoring systems were not developed for predicting post‐operative complications, they were associated with complications in our study. However, these four scoring systems have some significant limitations. The ideal scoring system is yet to be developed.
The residual fragments in patients with preoperative and intraoperative culture positivity may serve as an infection focus. The aim of this study was to assess the importance of residual fragments ...for developing SIRS in patients with stone culture and/or RPUC positivity. After obtaining institutional review board approval, a total of 729 patients who undergone PCNL for renal stones were included in this study. Residual fragments accepted to be positive if any fragment was detected irrespective of size. All patients were followed-up postoperatively for SIRS criteria. The patients were then followed-up for residual stone-related events and infectious complications. 94 of the 729 patients have developed SIRS postoperatively. SIRS positivity was more common among males and found to be associated with higher stone burden and presence of staghorn stone. Patients with residual fragments after PCNL also had higher rates of SIRS. In the subgroup analysis of 203 patients who had post-PCNL residual fragments, the peroperative stone and/or RPUC positivity was not found to be associated with the development of the SIRS. Although presence of residual fragments after PCNL is associated with SIRS development, stone culture and/or RPUC positivity has no additional risk for development of post-PCNL infectious complications in patients with residual fragments.
Purpose
The aim of this study was to present to the literature a rare injury mechanism that causes knee dislocation (KD) and describe its characteristics.
Methods
A retrospective review of patients ...with KD who were treated between January 2014 and December 2019 at our hospital was performed. Patients with KD due to rotavator machine injury were included in Group 1 and all patients with KD due to other etiological reasons were included in Group 2. Patients’ age, gender, side, injury mechanism, time to surgery, length of stay (LOS), operation time, follow-up time, neurological injury status, vascular injury status, open injury status, and surgical interventions were evaluated.
Results
A total of 34 patients were evaluated in the study. There was no statistically significant difference between the groups in terms of age, gender, side, or follow-up time (p = .915, p = 1.000, p = .682, p = .374, respectively). However, LOS and time to surgery were statistically significantly longer in Group 1 (p = .037, p = .010, respectively). Moreover, neurovascular damage was statistically significantly more common in Group 1.
Conclusion
As a rare injury mechanism for KD, rotavator machine injuries cause more neurovascular injuries in patients compared to other injury mechanisms and increase the time to surgery and LOS due to preoperative soft tissue damage.
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