Novel Au/Cu2NiSnS4 Nano-Heterostructure: Synthesis, Structure, Heterojunction Band Offset and Alignment, and Interfacial Charge Transfer Dynamics.

Considering the importance of physics and chemistry at material interfaces, we have explored the coupling of multinary chalcogenide semiconductor Cu2NiSnS4 nanoparticles (CNTS NPs) for the first time with the noble metal (Au) to form Au-CNTS nano-heterostructures (NHSs). The Au-CNTS NHSs is synthesized by a simple facile hot injection method. Synergistic experimental and theoretical approaches are employed to characterize the structural, optical, and electrical properties of the Au-CNTS NHSs. The absorption spectra demonstrate enhanced and broadened optical absorption in the ultraviolet-visible-near-infrared (UV-Vis-NIR) region, which is corroborated by cyclic voltammetry (CV) readings. CV measurements show type II staggered band alignment, with a conduction band offset (CBO) of 0.21 and 0.23 eV at the Au-CNTS/CdS and CNTS/CdS interface, respectively. Complementary first-principles density functional theory (DFT) calculations predict the formation of a stable Au-CNTS NHSs, with the Au nanoparticle transferring its electrons to the CNTS. Moreover, our interface analysis using ultrafast transient absorption experiments demonstrate that the Au-CNTS NHSs facilitates efficient transport and separation of photoexcited charge carriers when compared to pristine CNTS. The transient measurements further reveal a plasmonic electronic transfer from the Au nanoparticle to CNTS. Our advanced analysis and findings will prompt investigations into new functional materials and their photo/electrocatalysis and optoelectronic device applications in the future.

Interfacial band offset engineering with barium-doping towards enhanced performance of all inorganic CsPbI2Br perovskite solar cells.

This study investigates the incorporation of Ba2+ at a low concentration into CsPbI2Br, resulting in the formation of mixed CsPb1-xBaxI2Br perovskite films. Photovoltaic devices utilizing these Ba-doped CsPbI2Br (Ba-CsPbI2Br) perovskite films achieved a higher stabilized power conversion efficiency of 14.07% compared to 11.60% for pure CsPbI2Br films. First-principles density functional theory calculations indicate that the improved device performance can be attributed to the efficient transport of conduction electrons across the interface between Ba-CsPbI2Br and the TiO2 electron transporting layer (ETL). The Ba-CsPbI2Br/TiO2 interface exhibits a type-II staggered band alignment with a smaller conduction band offset (CBO) of 0.25 eV, in contrast to the CsPbI2Br/TiO2 interface with a CBO of 0.48 eV. The reduced CBO at the Ba-CsPbI2Br/TiO2 interface diminishes the barrier for conduction electrons to transfer from the Ba-CsPbI2Br layer to the TiO2 layer, facilitating efficient charge transport.

Synthesis, Structural and Optical Properties of ZrBi2Se6 Nanoflowers: A Next-Generation Semiconductor Alloy Material for Optoelectronic Applications.

ZrBi2Se6 nanoflower-like morphology was successfully prepared using a solvothermal method, followed by a quenching process for photoelectrochemical water splitting applications. The formation of ZrBi2Se6 was confirmed by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The estimated value of work function and band gap were found to be 5.5 and 2.26 eV measured using diffuse reflection spectroscopy and ultraviolet photoelectron spectroscopy, suggesting the potential candidate for water splitting. The highest current density of 9.7 µA/cm2 has been observed for the ZrBi2Se6 photoanode for the applied potential of 0.5 V vs SCE. The flat-band potential value was -0.46 V, and the 1.85 nm width of the depletion region is estimated from the Mott-Schottky (MS) analysis. It also reveals that the charge carrier density for the ZrBi2Se6 nanoflowers is 4.8 × 1015 cm-3. The negative slope of the MS plot indicates that ZrBi2Se6 is a p-type semiconductor. It was observed that ZrBi2Se6 nanoflowers had a high charge transfer resistance of ∼730 kΩ and equivalent capacitance of ∼40 nF calculated using electrochemical impedance spectroscopy (EIS) measurements. Using chronoamperometry, the estimated rise time and decay time were 50 ms and 0.25 s, respectively, which reveals the fast photocurrent response and excellent PEC performance of the ZrBi2Se6 photoanode. Furthermore, an attempt has been made to explain the PEC activity of ZrBi2Se6 nanoflowers using an energy band diagram. Thus, the initial results on ZrBi2Se6 nanoflowers appear promising for the PEC activity toward water splitting.

Cancer Stem Cell Markers, CD44 and ALDH1, for Assessment of Cancer Risk in OPMDs and Lymph Node Metastasis in Oral Squamous Cell Carcinoma.

Tumour heterogeneity in oral cancer is attributed to the presence of cancer stem cells (CSCs). CSCs are the most migratory and metastatic cellular subpopulation within tumours. Assessment of CSC markers as significant predictors of lymph node metastasis may prove valuable in the clinical setting. Furthermore, analysis of this panel of putative stem cell markers in oral dysplasia may additionally inform of the likelihood for oral potentially malignant disorders (OPMDs) to progress to oral squamous cell carcinoma (OSCC). The present study aims to assess the significance of CSC markers in the progression of OPMDs to OSCC and assessment of lymph node metastasis in OSCC. CD44 and ALDH1 were assessed immunohistochemically in 25 normal, 30 OPMDs, and 24 OSCCs. CD44 is a membranous marker and ALDH1 is a cytoplasmic marker. The immunohistochemical expression of these markers were compared between OPMDs with and without dysplasia, as well as between low-risk and high-risk dysplasias. Similarly, expression was compared between OSCC with and without lymph node metastasis and among grades of OSCC. Positive CD44 expression was seen in all normal mucosal tissues. The expression decreased from normal epithelium to OPMDs but increased in OSCC. CD44 expression was positive in 21 cases of OSCC (87.5%) and reduced from well-differentiated to poorly differentiated OSCC. CD44 staining index was higher in OSCC without lymph node metastasis (3.59) when compared with OSCC with lymph node metastasis (1.33). There was a statistically significant difference observed in the ALDH1 staining index among three groups (p < 0.05), with highest expression seen in OSCC. Within OPMDs, the ALDH1 staining index was statistically higher in OPMDs with dysplasia as compared to OPMDs without dysplasia. Furthermore, the expression was higher in OPMDs with high-risk dysplasia when compared with low-risk dysplasia, but this was not statistically significant (p = 0.82). In conclusion, The CD44 positive population possesses properties of CSCs in head and neck carcinoma, and continuous shedding could be found after CD44 down-regulation. The present study reports differences in ALDH1 expression between OPMDs with and without dysplasia, dysplastic and non-dysplastic epithelia, and low-risk and high-risk dysplasia. These findings may suggest ALDH1 as a specific marker for dysplasia. CD44 demonstrated a difference in staining index in OSCC without lymph node metastasis versus OSCC with lymph node metastasis. These findings may suggest CD44 as a marker for lymph node metastasis. Both proteins may play key roles in the tumorigenicity of CSCs in OPMDs and OSCC.

Enhanced Charge Carrier Separation and Improved Biexciton Yield at the p-n Junction of SnSe/CdSe Heterostructures: A Detailed Electrochemical and Ultrafast Spectroscopic Investigation.

Tin chalcogenides (SnX, X = S, Se)-based heterostructures (HSs) are promising materials for the construction of low-cost optoelectronic devices. Here, we report the synthesis of a SnSe/CdSe HS using the controlled cation exchange reaction. The (400) plane of SnSe and the (111) plane of CdSe confirm the formation of an interface between SnSe and CdSe. The Type I band alignment is estimated for the SnSe/CdSe HS with a small conduction band offset (CBO) of 0.72 eV through cyclic voltammetry measurements. Transient absorption (TA) studies demonstrate a drastic enhancement of the CdSe biexciton signal that points toward the hot carrier transfer from SnSe to CdSe in a short time scale. The fast growth and recovery of CdSe bleach in the presence of SnSe indicate charge transfer back to SnSe. The observed delocalization of carriers in these two systems is crucial for an optoelectronic device. Our findings provide new insights into the fabrication of cost-effective photovoltaic devices based on SnSe-based heterostructures.

Ternary Cu2SnS3: Synthesis, Structure, Photoelectrochemical Activity, and Heterojunction Band Offset and Alignment.

Ternary Cu2SnS3 (CTS) is an attractive nontoxic and earth-abundant absorber material with suitable optoelectronic properties for cost-effective photoelectrochemical applications. Herein, we report the synthesis of high-quality CTS nanoparticles (NPs) using a low-cost facile hot injection route, which is a very simple and nontoxic synthesis method. The structural, morphological, optoelectronic, and photoelectrochemical (PEC) properties and heterojunction band alignment of the as-synthesized CTS NPs have been systematically characterized using various state-of-the-art experimental techniques and atomistic first-principles density functional theory (DFT) calculations. The phase-pure CTS NPs confirmed by X-ray diffraction (XRD) and Raman spectroscopy analyses have an optical band gap of 1.1 eV and exhibit a random distribution of uniform spherical particles with size of approximately 15-25 nm as determined from high-resolution transmission electron microscopy (HR-TEM) images. The CTS photocathode exhibits excellent photoelectrochemical properties with PCE of 0.55% (fill factor (FF) = 0.26 and open circuit voltage (Voc) = 0.54 V) and photocurrent density of -3.95 mA/cm2 under AM 1.5 illumination (100 mW/cm2). Additionally, the PEC activities of CdS and ZnS NPs are investigated as possible photoanodes to create a heterojunction with CTS to enhance the PEC activity. CdS is demonstrated to exhibit a higher current density than ZnS, indicating that it is a better photoanode material to form a heterojunction with CTS. Consistently, we predict a staggered type-II band alignment at the CTS/CdS interface with a small conduction band offset (CBO) of 0.08 eV compared to a straddling type-I band alignment at the CTS/ZnS interface with a CBO of 0.29 eV. The observed small CBO at the type-II band aligned CTS/CdS interface points to efficient charge carrier separation and transport across the interface, which are necessary to achieve enhanced PEC activity. The facile CTS synthesis, PEC measurements, and heterojunction band alignment results provide a promising approach for fabricating next-generation Cu-based light-absorbing materials for efficient photoelectrochemical applications.

Revealing the electronic structure, heterojunction band offset and alignment of Cu2ZnGeSe4: a combined experimental and computational study towards photovoltaic applications.

Cu2ZnGeSe4 (CZGSe) is a promising earth-abundant and non-toxic semiconductor material for large-scale thin-film solar cell applications. Herein, we have employed a joint computational and experimental approach to characterize and assess the structural, optoelectronic, and heterojunction band offset and alignment properties of a CZGSe solar absorber. The CZGSe films were successfully prepared using DC-sputtering and e-beam evaporation systems and confirmed by XRD and Raman spectroscopy analyses. The CZGSe films exhibit a bandgap of 1.35 eV, as estimated from electrochemical cyclic voltammetry (CV) measurements and validated by first-principles density functional theory (DFT) calculations, which predicts a bandgap of 1.38 eV. A fabricated device based on the CZGSe as a light absorber and CdS as a buffer layer yields power conversion efficiency (PCE) of 4.4% with VOC of 0.69 V, FF of 37.15, and Jsc of 17.12 mA cm-2. Therefore, we suggest that interface and band offset engineering represent promising approaches to improve the performance of CZGSe devices by predicting a type-II staggered band alignment with a small conduction band offset of 0.18 eV at the CZGSe/CdS interface.

CBCT Evaluation of Gutta-Percha Removal Using Protaper and Mtwo Retreatment Files, Wave One, and Hedstrom Files: An Ex Vivo Study.

Objectives: This study aimed to evaluate the efficacy of ProTaper, Mtwo, and WaveOne retreatment files and Hedstrom files for removal of gutta-percha from the straight root canals using cone-beam computed tomography (CBCT). Materials and Methods: Forty freshly extracted single-rooted and single-canal teeth were selected for this study. The teeth were decoronated, and biomechanical preparation was performed up to #30 K-file. The root canals were obturated using lateral compaction technique with gutta-percha and Resilon sealer. The teeth were then randomly divided into 4 groups, and CBCT images were obtained. All the canals were then retreated with either ProTaper retreatment files, Mtwo retreatment files, WaveOne files, or Hedstrom files. The surface area of the remaining filling material after the retreatment procedure was quantified by CBCT. Statistical analysis was performed via one-way ANOVA and the Tukey-Kramer multiple comparisons test. Results: None of the file systems could completely remove the filling material from the canals. Data analysis revealed significant differences between the groups in the apical and middle thirds (P<0.05). Conclusion: All the file systems left some filling material in the canals. Mtwo retreatment files had maximum efficacy for removal of filling materials in comparison with other files. WaveOne files can also be used for root canal retreatment.

Experimental and Theoretical Study into Interface Structure and Band Alignment of the Cu2Zn1-x Cd x SnS4 Heterointerface for Photovoltaic Applications.

To improve the constraints of kesterite Cu2ZnSnS4 (CZTS) solar cell, such as undesirable band alignment at p-n interfaces, bandgap tuning, and fast carrier recombination, cadmium (Cd) is introduced into CZTS nanocrystals forming Cu2Zn1-x Cd x SnS4 through cost-effective solution-based method without postannealing or sulfurization treatments. A synergetic experimental-theoretical approach was employed to characterize and assess the optoelectronic properties of Cu2Zn1-x Cd x SnS4 materials. Tunable direct band gap energy ranging from 1.51 to 1.03 eV with high absorption coefficient was demonstrated for the Cu2Zn1-x Cd x SnS4 nanocrystals with changing Zn/Cd ratio. Such bandgap engineering in Cu2Zn1-x Cd x SnS4 helps in effective carrier separation at interface. Ultrafast spectroscopy reveals a longer lifetime and efficient separation of photoexcited charge carriers in Cu2CdSnS4 (CCTS) nanocrystals compared to that of CZTS. We found that there exists a type-II staggered band alignment at the CZTS (CCTS)/CdS interface, from cyclic voltammetric (CV) measurements, corroborated by first-principles density functional theory (DFT) calculations, predicting smaller conduction band offset (CBO) at the CCTS/CdS interface as compared to the CZTS/CdS interface. These results point toward efficient separation of photoexcited carriers across the p-n junction in the ultrafast time scale and highlight a route to improve device performances.

Clinical outcome of severe sepsis and septic shock in critically ill children.

Information concerning the clinical outcome of severe sepsis and septic shock among the burden of tropical infections in children is limited, particularly in low-income settings. We conducted a prospective consecutive cohort study in all children aged 1 month to 16 years needing paediatric intensive care between 1 January 2017 and 31 December 2018. Demographic details, presenting symptoms and duration, associated co-morbidity and organ dysfunction were recorded. Clinical and laboratory parameters discriminating between survivors and non-survivors were evaluated. Most presented with respiratory or central nervous system derangement along with cardiovascular dysfunction. Haematological involvement was almost invariably found on diagnostic evaluation. Those children with ≥3 systems involved had higher odds of mortality. Dengue was seen in half the patients, being the commonest tropical infection. Not surprisingly, non-survivors were younger, had rapid progression of illness and needed ventilation more often within the first hour of admission. However, in multivariable regression analysis, only procalcitonin levels were associated with increased risk of mortality. We conclude that that tropical infections causing severe sepsis and septic shock are an important cause of mortality. There are, however, no clinical parameters which differentiate reliably between survivors and non-survivors.

Interface Structure and Band Alignment of CZTS/CdS Heterojunction: An Experimental and First-Principles DFT Investigation.

We report a phase-pure kesterite Cu2ZnSnS4 (CZTS) thin films, synthesized using radio frequency (RF) sputtering followed by low-temperature H2S annealing and confirmed by XRD, Raman spectroscopy and XPS measurements. Subsequently, the band offsets at the interface of the CZTS/CdS heterojunction were systematically investigated by combining experiments and first-principles density functional theory (DFT) calculations, which provide atomic-level insights into the nature of atomic ordering and stability of the CZTS/CdS interface. A staggered type II band alignment between the valence and conduction bands at the CZTS/CdS interface was determined from Cyclic Voltammetry (CV) measurements and the DFT calculations. The conduction and valence band offsets were estimated at 0.10 and 1.21 eV, respectively, from CV measurements and 0.28 and 1.15 from DFT prediction. Based on the small conduction band offset and the predicted higher positions of the VBmax and CBmin for CZTS than CdS, it is suggested photogenerated charge carriers will be efficient separated across the interface, where electrons will flow from CZTS to the CdS and and vice versa for photo-generated valence holes. Our results help to explain the separation of photo-excited charge carriers across the CZTS/CdS interface and it should open new avenues for developing more efficient CZTS-based solar cells.

Boosting the Efficiency of Quantum Dot-Sensitized Solar Cells through Formation of the Cation-Exchanged Hole Transporting Layer.

In search of a viable way to enhance the power conversion efficiency (PCE) of quantum dot-sensitized solar cells, we have designed a method by introducing a hole transporting layer (HTL) of p-type CuS through partial cation exchange process in a postsynthetic ligand-assisted assembly of nanocrystals (NCs). High-quality CdSe and CdSSe gradient alloy NCs were synthesized through colloidal method, and the charge carrier dynamics was monitored through ultrafast transient absorption measurements. A notable increase in the short-circuit current concomitant with the increase in open-circuit voltage and the fill factor led to 45% increment in PCE for CdSe-based solar cells upon formation of the CuS HTL. Electrochemical impedance spectroscopy further revealed that the CuS layer formation increases recombination resistance at the TiO2/NC/electrolyte interface, implying that interfacial recombination gets drastically reduced because of smooth hole transfer to the redox electrolyte. Utilizing the same approach for CdSSe alloy NCs, the highest PCE (4.03%) was obtained upon CuS layer formation compared to 3.26% PCE for the untreated one and 3.61% PCE with the conventional ZnS coating. Therefore, such strategies will help to overcome the kinetic barriers of hole transfer to electrolytes, which is one of the major obstacles of high-performance devices.

CZTS x Se1-x nanocrystals: Composition dependent method of preparation, morphological characterization and cyclic voltammetry data analysis.

In this article, synthesis procedures of preparation of copper zinc tin sulpho-selenide (CZTS x Se1-x ) alloy nanocrystals and the data acquired for the material characterization are presented. This data article is related to the research article doi: http://dx.doi.org/10.1016/j.solmat.2016.06.030 (Jadhav et al., 2016) [1]. FTIR data have been presented which helped in confirmation of adsorption of oleylamine on CZTS x Se1-x . Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) data have been presented which have been used to reveal the morphological details of the nanocrystals. The Energy dispersive X-ray analysis (EDAX) based elemental mapping data has been presented to confirm the elemental composition of nanocrystals. Procedure for the preparation of CZTS x Se1-x based working electrode for the CV measurements have been given. The summary table for the optical, electrochemical band gaps, valance and conduction band edges as a function of composition are listed for the ready reference.

Primary hepatic choriocarcinoma: a rare cause of spontaneous haemoperitoneum in an adult.

Choricarcinoma is a beta human chorionic gonadotrophin secreting neoplasm pertinent to uterus and pregnancy mostly. It occurs primarily in gonads but rarely in extragonadal sites. Primary hepatic choriocarcinoma is an extremely rare tumor. Most of the reported cases are seen in infants representing metastasis from an occult placental choriocarcinoma. Till date, only 7 cases of primary hepatic choriocarcinoma in adults have been reported in literature. We present a case of a 40-yearold male presenting as haemoperitoneum due to ruptured hepatic tumor. He underwent emergency left lateral segmentectomy. He died on 10(th) postoperative day. The surgical specimen and autopsy findings confirmed it to be primary hepatic choriocarcinoma. This is the first case report from Indian Subcontinent. A brief case report and review of literature is presented.

IVC Thrombectomy in Renal Cell Carcinoma-Analysis of Out Come Data of 100 Patients and Review of Literature.

To review our experience of RCC with IVC thrombus in terms of clinical presentation, principles of surgical management in contemporary era, also an impact of clinico-pathological factors on prognosis. Total 100 patients who underwent radical nephrectomy and IVC thrombectomy between 1991-2008 were included in this retrospective analysis. Data was analysed in terms of clinical pathological factors, survivals and compared with contemporary literature. The extent tumour thrombus was infrahepatic in 58 retro hepatic in 28 and suprahepatic in 14 patients including 6 with right atrial thrombus. The immediate postoperative mortality was 2% and incidence of major postoperative non fatal complications was 38%, which were managed conservatively. The overall and disease free 5 year survival was 63% and 55%. Further amongst the histological types, patients with clear cell tumours had the best (DFS- 71.42%), and those with papillary had the poor (DFS- 30.76%) outcome. Grade II tumors had better survivals as compared to grade IV (DFS 75.39% vs 23.52%, p < 0.05). Loco- regional extent wise 74% patients without perinephric fat invasion were free from disease at 5 years as compared to 30% of those who had perinephric fat invasion (p < 0.01). Similarly 5 year DFS was 76.11% in patients with negative nodes as compared to 12% in positive nodes (p < 0.01). In conclusion radical nephrectomy with IVC thrombectomy still remains the most effective therapeutic option in management in this clinical setting. Although this is complicated surgery success with multi disciplinary approach excellent survival outcome can be obtained. Further pathological factors, such as loco-regional spread and grade of tumor, rather than clinical factors influence long term survival.

Impact of Gleason pattern up gradation after radical prostatectomy for carcinoma prostate patients with low biopsy score (≤ 6).

CONTEXT: Biopsy Gleason score (b-GS) is often different from the Gleason score obtained after analysis of radical prostatectomy (RP) specimen (rp-GS). Upgradation has an important implication in decision making for cancer prostate management, and is the focus of this study. AIM: To evaluate Gleason score upgradation after radical prostatectomy with low biopsy score (≤ 6) and its correlation to pathological findings and outcome. SETTINGS AND DESIGN: This was a retrospective analysis of 257 cases of prostate cancer patients with initial b-GS ≤ 6, over a period of 14 years. MATERIALS AND METHODS: Data were divided into two groups according to (rp- GS) as 1) Group A (n=151; rp-GS ≤ 6 ) 2) and Group B(n=106; rp-GS ≥7). Both groups were compared in terms of the following: 1) preoperative variables e.g. age, PSA, transurethral resection of prostate (TURP) status, clinical T stage; 2) pathological features - rp GS, pathological stage (pT), capsular penetration, cut margin, seminal vesicle and lymph node status; 3) biochemical recurrence, overall and cancer specific mortality. STATISTICAL ANALYSIS USED: Student's t test and Chi-square test. RESULTS: Group B had worse pathological features, except lymph node invasion, and they received significantly more adjuvant hormonal/local radiotherapy and had higher recurrence rate. However, the overall and cancer-specific mortality were similar in both the groups. CONCLUSIONS: b-GS upgradation after radical prostatectomy is frequent and correlates with adverse pathological features, higher use of adjuvant therapy and higher recurrence rate. In Group B, adjuvant therapy delays the biochemical or clinical relapse and controls mortality in short-term follow up. Group A had favorable pathological findings and less recurrence rate.