bluuebunny/crossref_metadata_2025 huggingface dataset:
Can white-light endoscopy or narrow-band imaging avoid biopsy of colorectal endoscopic mucosal resection scars? A multicenter randomized single-blind crossover trial
Authors: João Mafalda , Areia Miguel , Pinto-Pais Teresa , Gomes Luís Correia , Saraiva Sofia , Alves Susana , Elvas Luís , Brito Daniel , Saraiva Sandra , Teixeira-Pinto Armando , Claro Isabel , Dinis-Ribeiro Mário , Cadime Ana Teresa
Published: January 2023

Background Current guidelines suggest that routine biopsy of post-endoscopic mucosal resection (EMR) scars can be abandoned, provided that a standardized imaging protocol with virtual chromoendoscopy is used. However, few studies have examined the accuracy of advanced endoscopic imaging, such as narrow-band imaging (NBI) vs. white-light endoscopy (WLE) for prediction of histological recurrence. We aimed to assess whether NBI accuracy is superior to that of WLE and whether one or both techniques can replace biopsies.

Methods The study was a multicenter, randomized, pathologist-blind, crossover trial, with consecutive patients undergoing first colonoscopy after EMR of lesions ≥ 20 mm. Computer-generated randomization and opaque envelope concealed allocation. Patients were randomly assigned to scar examination with NBI followed by WLE (NBI + WLE), or WLE followed by NBI (WLE + NBI). Histology was the reference method, with biopsies being performed for all tissues.

Results The study included 203 scars (103 in the NBI + WLE group, 100 in the WLE + NBI group). Recurrence was confirmed histologically in 29.6 % of the scars. The diagnostic accuracy of NBI was not statistically different from that of WLE (95 % [95 %CI 92 %–98 %] vs. 94 % [95 %CI 90 %–97 %]; P = 0.48). The negative predictive values (NPVs) were 96 % (95 %CI 93 %–99 %) for NBI and 93 % (95 %CI 89 %–97 %) for WLE (P = 0.06).

Conclusions The accuracy of NBI for the diagnosis of recurrence was not superior to that of WLE. Endoscopic assessment of EMR scars with WLE and NBI achieved an NPV that would allow routine biopsy to be avoided in cases of negative optical diagnosis.
Recurrent Sensory-Motor Neuropathy Mimicking CIDP as Predominant Presentation of PDH Deficiency
Authors: Croci Carolina , Cataldi Matteo , Baratto Serena , Bruno Claudio , Trucco Federica , Doccini Stefano , Romano Alessandro , Nesti Claudia , Santorelli Filippo Maria , Fiorillo Chiara
Published: January 2023

Introduction Pyruvate dehydrogenase complex (PDH) deficiency (Online Mendelian Inheritance in Man # 312170) is a relatively common mitochondrial disorder, caused by mutations in the X-linked PDHA1 gene and presenting with a variable phenotypic spectrum, ranging from severe infantile encephalopathy to milder chronic neurological disorders.

Isolated peripheral neuropathy as predominant clinical presentation is uncommon.

Results We report on a patient, now 21 years old, presenting at the age of 2 years with recurrent symmetric weakness as first symptom of a PDH deficiency. Neurophysiological evaluation proving a sensory-motor polyneuropathy with conduction blocks and presence of elevated cerebrospinal fluid proteins, suggested a chronic inflammatory demyelinating polyneuropathy. The evidence of high serum lactate and the alterations in oxidative metabolism in muscle biopsy pointed toward the final diagnosis. After starting nutritional supplements, no further episodes occurred. A hemizygous mutation in PDHA1 (p.Arg88Cys) was identified. This mutation has been previously described in five patients with a similar phenotype. A three-dimensional reconstruction demonstrated that mutations affecting this arginine destabilize the interactions between the subunits of the E1 complex.

Conclusion We summarize the clinical and genetic characteristics of one patient with PDH deficiency presenting isolated peripheral nervous system involvement. This study highlights that the diagnosis of PDH deficiency should be considered in children with unexplained peripheral neuropathy, even with features suggestive of acquired forms, especially in case of early onset and limited response to treatment. A simple analysis of lactic acid could help to target the diagnosis.

In addition, we suggest that the residue Arg88 is the most frequently involved in this specific phenotype of PDH deficiency.
Endoscopic management of gastrointestinal wall defects, fistula closure, and stent fixation using through-the-scope tack and suture system
Authors: Krishnan Arunkumar , Shah-Khan Sardar M. , Hadi Yousaf , Patel Neel , Thakkar Shyam , Singh Shailendra
Published: January 2023

Background Multiple devices are available for tissue approximation. A new through-the-scope suturing (TTSS) device has recently been introduced; however, data on its scope of use and clinical effectiveness are limited. We aimed to assess the clinical course and effectiveness of this TTSS device.

Methods A retrospective review was performed for consecutive patients who underwent TTSS application. Primary outcomes were technical and clinical success, and secondary outcomes included adverse events and long-term clinical success.

Results 53 patients (mean age 67.8 years; 69.8 % females) were included, with a mean defect size of 32.6 mm (SD 11.9). Technical success was achieved in 51 patients (96.2 %). Clinical success was achieved in 49 patients (92.4 %). Two patients (3.8 %) experienced failed fistula closure after technical success. Long-term follow-up (> 30 days) was available for 45 patients (84.9 %), with a mean follow-up of 7.2 months. One patient (1.9 %) had self-reported bleeding that did not require further intervention.

Conclusions TTTS was an effective and safe method for the closure of large gastrointestinal defects and could be used for fistula closure and stent fixation, making it a valuable addition to the armamentarium of endoscopic closure devices.
Imaging Recommendations for Diagnosis, Staging, and Management of Ovarian and Fallopian Tube Cancers
Authors: Rupa Renganathan , Prema Renganathan , Popat Palak Bhavesh , Manchanda Smita , Venkatesh Kasi , Chandramohan Anuradha , Subbian Anbukkani , Rangarajan Bharath
Published: January 2023

Ovarian malignancy the third most common gynecological malignancy and is the leading cause of death in women. Non-specific clinical presentation delays the diagnosis, and they often present in the advanced stage of disease. No imaging modality is recommended for screening as there is no significant mortality reduction. Ultrasound (USG) is usually the initial modality in suspected ovarian mass. MRI is recommended for the characterization of indeterminate ovarian or adnexal mass on USG. CT abdomen and pelvis with oral and IV contrast is the recommended imaging modality in staging the disease, predicting the resectability and in selecting the patients who would benefit from neoadjuvant chemotherapy. Early ovarian cancers are staged by post-surgical histology and undergo upfront surgery. Advanced disease benefit by neoadjuvant chemotherapy and less morbidity by interval cytoreduction where image-guided biopsy is performed for histological diagnosis. Follow-up recommendations are based on tumor histology. CT/PET CT is recommended for diagnosing recurrence.
Is It Possible to Eliminate Postoperative Shunt Infections?: Results of a Modified Hydrocephalus Clinical Research Network Protocol
Authors: Elbaroody Mohammad , Ezz Adham , Eldessouky Amr Helmy , Hassan Ahmed A. Aziz N. , Elsharkawy Ahmed Abbas , Ali Khaled Bassim , Refaee Ehab Ahmed El
Published: January 2023

Background Postoperative shunt infection is a nightmare in neurosurgical practice with additional morbidity and mortality. A lot of protocols have contributed to the reduction of ventriculoperitoneal shunt (VPS) infections but not eradication. The aim of the study was to evaluate the rigid application of a modified Hydrocephalus Clinical Research Network (HCRN) protocol in the prevention of postoperative shunt infection.

Methods We retrospectively evaluated children with congenital hydrocephalus who underwent VPS insertion, and in whom the protocol was applied from June 2019 to January 2020. Follow-up ranged from 11 to 24 months.

Results Thirty-seven procedures were performed including 35 primary shunt insertions and two revision surgeries. The median age was 5 months (range, 1–30 months), and 25 patients were males. The most common cause for VPS placement was congenital hydrocephalus without identifiable cause in 28 cases (80%). The endoscope-assisted technique was used in the insertion of the proximal end in six cases (17%). The mean follow-up was 19.4 months (11–24 months). The rate of shunt infection was 0% till the last follow-up.

Conclusion The preliminary results showed an effective method for the prevention of postoperative shunt infections using the modified protocol. These initial findings need to be validated in a large prospective study before widespread application can be recommended.
Postoperative Discomfort Among Laparotomy Patients from a Selected Hospital at Mangaluru: An Observational Study
Authors: Latha S. , Kamath Neetha , Joseph Gincy
Published: January 2023

Background Factors causing postoperative discomfort after laparotomy are numerous and must be explored in depth. The postoperative distress may significantly affect the patient's state of well-being. Hence, the present study aims to assess the factors contributing to discomfort after laparotomy.

Aim The aim was to assess and compare the discomfort between open and laparoscopic abdominal surgery.

Objectives of the Study

1. To analyze the causes of patient's discomfort after abdominal surgery.

2. To compare the discomfort between open and laparoscopic abdominal surgery.

3. To determine the association between pain and selected variables among open and laparoscopic abdominal surgery.

Materials and Methods An exploratory approach with a prospective observational design was adopted for this study. Using the purposive sampling technique, 100 patients were selected to open and 100 to laparoscopic abdominal surgery groups. Data were collected using demographic and clinical proforma and standardized postoperative discomfort inventory 6 and 24 hours after the surgery. The assessment focused on the study variables such as symptoms after the surgery and the factors contributing to the postoperative discomfort.

Statistical Analysis The collected data were analyzed using descriptive and inferential statistics using the SPSS software version 20.

Results Among 200 participants, most of the open (68%) and laparoscopic abdominal surgeries (42%) belong to 25 to 35 years of age. Also, 54% and 13% were diabetic in open and laparoscopic abdominal surgery groups, respectively. Most samples (56% in open and 68% in laparoscopic surgery) stayed 5 and 10 hours in postoperative ICU. In open and laparoscopic abdominal surgeries, pain is the primary (100%) cause of postoperative discomfort after 6 hours of surgery. Movement restriction is also the reason for significant discomfort both in open (98%) and laparoscopic (100%) abdominal surgeries.

In contrast, pain (99% and 100%), movement restriction (92% and 95%), and abdominal distention (61% and 34%) were the major problems contributing to the patient's discomfort after 24 hours of both open and laparoscopic surgeries too. There was a significant difference in causes of patient discomfort between open and laparoscopic abdominal surgery after 6 hours (P < 0.05), except for discomfort related to IV drip (P = 0.852), constipation (P = 0.2), and chills (P = 0.6).

Conclusion Even though pain is the major distressing factor both in open and laparoscopic surgeries, the current study highlights a few other factors that affect postoperative recovery. Nurses' attention to such distressing factors will fasten patients' recovery and quality of life after abdominal surgery.
Real-Time Ultrasound Tip Location Reduces Malposition and Radiation Exposure during Epicutaneo-Caval Catheter Placement in Neonates
Authors: D'Andrea Vito , Prontera Giorgia , Cota Francesco , Russo Rosellina , Barone Giovanni , Vento Giovanni
Published: January 2023

Objective Epicutaneo-caval catheters (ECCs) are essential for the care of sick infants who require long-term medical and nutritional management. The aim of this study was to investigate the use of real-time ultrasound as an alternative to X-rays to reduce the incidence of primary malpositions during catheter insertion.

Study Design Data on ECCs were retrospectively collected in a tertiary neonatal intensive care unit. Catheter were analyzed considering the tip location technique (standard chest–abdominal radiograph vs real-time ultrasound)

Results A total of 248 ECCs were analyzed. Of these, 118 catheters had primary malposition (47.6%). The tip of 165 catheters was assessed using standard chest–abdominal X-rays and 107 (64.8%) were found to be in an inappropriate location. In the group of 83 catheters that were placed using real-time ultrasound for tip location, only 11 catheters (13.2%) had primary malposition. The rate of malposition among the two groups showed a statistically significant difference (p < 0.001). Hypothetically, 300 chest X-rays could have been saved if real-time ultrasound had been used to locate the tip, reducing radiation exposure to infants.

Conclusion The use of a real-time ultrasound may be beneficial in reducing primary catheter malpositions compared with conventional radiography. In addition, secondary malpositions and catheter-related complications can be monitored over time.

Key Points
Does Fissureless Videothoracoscopic Lobectomy Help for Postoperative Air Leak?
Authors: Kara Murat , Özkan Berker , Duman Salih , Erdoğdu Eren , Sarıgül Arda , Toker Alper
Published: January 2023

Background Postoperative air leak is a common problem in patients undergoing pulmonary resections. A conventional fissure dissection technique during videothoracoscopic lobectomy, particularly in patients with fused fissures is very likely to result in parenchymal damage and prolonged air leak (PAL). In contrast, fissureless video-assisted thoracoscopic surgery (VATS) lobectomy may have advantages regarding PAL and hospital stay.

Methods We conducted a retrospective study consisting of 103 consecutive patients who underwent a VATS lobectomy either with a conventional or fissureless technique and statistically analyzed the results particularly with respect to PAL, chest tube duration (CTD), and length of hospital stay (LOS).

Results We had 21 (20.4%) cases with PAL. Gender (p = 0.009), histological size of tumor (p = 0.003), and surgical technique (p = 0.009) showed statistically significant differences for PAL in contingency tables. Significant predictors for PAL in univariate analysis were male sex (p = 0.017), histological size of tumor more than 24 mm (p = 0.005), and conventional technique (p = 0.017). Similarly, multivariate analysis revealed male sex (p = 0.036), histological size of tumor more than 24 mm (p = 0.043), and conventional technique (p = 0.029) as significant predictors for PAL. In addition, both the medians of CTD (p = 0.015) and LOS (p = 0.005) were comparably lesser as 3 days, in patients who underwent fissureless videothoracoscopic lobectomy.

Conclusion The fissureless technique helps for PAL in patients undergoing videothoracoscopic lobectomy.
The Impact of Exercise on Motor Recovery after Long Nerve Grafting—Experimental Rat Study
Authors: Camuzard Olivier , Lu Johnny Chuieng-Yi , Abbadi Sam El , Chang Tommy Nai-Jen , Chuang David Chwei-Chin
Published: January 2023

Background Long nerve grafting often results in unsatisfactory functional outcomes. In this study we aim to investigate the effect of swimming exercise on nerve regeneration and functional outcomes after long nerve grafting.

Methods A reversed long nerve graft was interposed between C6 and the musculocutaneous nerve in 40 rats. The rats were divided into four groups with 10 in each based on different postoperative swimming regimes for rehabilitation: group A, continuous exercise; group B, early exercise; group C, late exercise; and group D, no exercise (control group). A grooming test was assessed at 4, 8, 12, and 16 weeks postoperatively. Biceps muscle compound action potential (MCAP), muscle tetanic contraction force (MTCF), and muscle weights were assessed after 16 weeks. Histomorphometric analyses of the musculocutaneous nerves were performed to examine nerve regeneration.

Results The grooming test showed all groups except group D demonstrated a trend of progressive improvement over the whole course of 16 weeks. Biceps MCAP, MTCF, and muscle weights all showed significant better results in the exercise group in comparison to the group D at 16 weeks, which is especially true in groups A and B. Nerve analysis at 16 weeks, however, showed no significant differences between the exercise groups and the control group.

Conclusions Swimming after long nerve grafting can significantly improve muscle functional behavior and volume. The effect is less evident on nerve regeneration. Continuous exercise and early exercise after surgery show more optimal outcomes than late or no exercise. Having a good habit with exercise in the early period is thought as the main reason. Further studies are needed to determine the optimal exercise regimen.
Free Flaps in Sternal Osteomyelitis After Median Sternotomy: A Center's 12-Year Experience
Authors: Georgiou Iakovos , Ioannou Christos I. , Schmidt Jeremias , Eschborn Johannes , Mostofizadeh-Haghighi Giw , Infanger Manfred , Ghods Mojtaba , Kruppa Philipp
Published: January 2023

Background Adequate treatment of deep sternal wound infections (DSWIs) after open thoracic surgery still presents a major challenge. This study retrospectively analyzes the results of a single center's 12-year experience in treating DSWI, with special emphasis on free flap reconstruction.

Methods In this single-center, retrospective study, all patients admitted with the diagnosis of DSWI after open thoracic surgery between 2009 and 2020 were included. A comparative analysis was performed between: (1) pedicled versus free flaps, (2) the center's two workhorse flaps—the pedicled latissimus dorsi (pLD) versus free anterolateral thigh (fALT) flaps, as well as (3) myocutaneous (MC) versus fasciocutaneous (FC) flaps. Primary endpoints were length of hospital stay (LOS) after reconstruction and in-hospital mortality.

Results Of a total of 165 patients included, 152 underwent DSWI defect reconstruction with a total of 12 different reconstruction methods. Although the defect size was larger in patients who underwent free flap coverage, and the risk profile in the fALT and FC flap groups was higher, the LOS after reconstruction (in days) did not differ significantly between the groups (pedicled vs. free flaps: 23 vs. 28, p > 0.05; pLD vs. fALT: 24.5 vs. 26, p > 0.05; MC vs. FC flaps: 23 vs. 26, p > 0.05). Also, no significant differences were found in terms of in-hospital mortality when comparing the groups (pedicled vs. free flaps: 11.2 vs. 17.4%, p > 0.05; pLD vs. fALT: 11.5 vs. 12.5%, p > 0.05; MC vs. FC flaps: 12.9 vs. 12.5%, p > 0.05).

Conclusion With proper patient selection, free tissue transfer is a valuable alternative in the treatment of sternal dehiscence after a DSWI. Furthermore, our data demonstrate that MC flaps are not necessarily superior to FC flaps in the reconstruction of sternal osteomyelitis defects.
Spinal Dysraphism Spectrum: A Novel Protocol-based Approach for Accurate Diagnosis on Imaging
Authors: Rana Abhilasha , Krishnan Venkatram , Jamwal Rupie
Published: January 2023

The spectrum of spinal dysraphism includes various congenital anomalies of the spinal column and spinal cord. Clinical manifestations are varied and range from paraparesis, gastrointestinal, genitourinary, and musculoskeletal anomalies to asymptomatic cases depending on the level and extent of spinal involvement. Magnetic resonance imaging is the gold standard for assessing these complex spinal anomalies. Even for the experienced radiologist, diagnosis can be challenging in complex cases. It is essential to be aware of the normal embryological developmental stages of the spine for an adequate understanding of the complex anatomy, pathogenesis, and cliniconeuroradiological classification of spinal dysraphism, which is necessary for accurately diagnosing each case as a particular pathological entity. In this pictorial essay, we have depicted the stages and process of spinal embryogenesis, cliniconeuroradiological classification, and the imaging spectrum of spinal dysraphism. As the confusing terminologies and the numerous variants can potentially lead to misdiagnosis, we have proposed a step-wise protocol-based imaging approach to analyze each case and arrive at the correct diagnosis systematically. This would be particularly helpful in confusing and difficult cases, as accurate and early diagnosis is crucial for appropriate patient management.
Deviance as an historical artefact: a scoping review of psychological studies of body modification
Authors: Owens Rebecca , Filoromo Steven J. , Landgraf Lauren A. , Lynn Christopher D. , Smetana Michael R. A.
Published: January 2023

Body modification is a blanket term for tattooing, piercing, scarring, cutting, and other forms of bodily alteration generally associated with fashion, identity, or cultural markings. Body modifications like tattooing and piercing have become so common in industrialised regions of the world that what were once viewed as marks of abnormality are now considered normal. However, the psychological motivations for body modification practices are still being investigated regarding deviance or risky behaviours, contributing to a sense in the academic literature that body modifications are both normal and deviant. We explored this inconsistency by conducting a scoping review of the psychological literature on body modifications under the assumption that the psychological and psychiatric disciplines set the standard for related research. We searched for articles in available online databases and retained those published in psychology journals or interdisciplinary journals where at least one author is affiliated with a Psychology or Psychiatry programme (N = 94). We coded and tabulated the articles thematically, identifying five categories and ten subcategories. The most common category frames body modifications in general terms of risk, but other categories include health, identity, credibility/employability, and fashion/attractiveness. Trends in psychology studies seem to follow the shifting emphasis in the discipline from a clinical orientation regarding normality and abnormality to more complex social psychological approaches.
Understanding media empowerment: citizen journalism in Palestine
Authors: Horoub Ibrahim
Published: January 2023

This study addresses the nature of citizen journalism in Palestine, with the chief aim of identifying its role in promoting professionalism, ethics, and objectivity, and empowering digital media, information accessibility, and democratization of media production. To this end, this study uses data from different universities across Palestine obtained through surveys that address digital media empowerment and non-professional users in the new media landscape. The study sample used was selected using the stratified sampling method. Upon completion of a pilot test, a total of 300 questionnaires were distributed among undergraduates of 10 universities across Palestine based on their willingness to participate and availability. Our results suggest that official media outlets can benefit from citizen journalism by providing accurate and valid sources of information to citizen journalists to increase engagement among their audiences as a result of enhanced perceptions of independency and credibility. However, our findings also reveal that citizen journalism does not make a significant difference in undermining gatekeeping practices over new media content in Palestine. Moreover, the results show that there is no relationship or correlation between the idea of adopting citizen journalism as a complementary method to traditional journalism and the credibility and reliability of news stories presented by citizen journalists.
Evidence of excited-state lifetime enhancement in dimyristoyl-phosphocholine nanodiscs by ultraviolet absorption spectroscopy
Authors: Kocheril Philip A. , Hiller Miranda I. , Kubicek-Sutherland Jessica Z.
Published: January 2023

Ultraviolet absorption spectroscopy is an analytical tool that is commonly utilized to determine protein concentrations, primarily due to characteristic absorption of tryptophan and tyrosine at 280 nm. Accurate concentration determination is essential to the accuracy of many biophysical techniques, and ultraviolet absorption provides a convenient and rapid method to assess protein concentration. However, the widespread usage of this method assumes that ultraviolet absorption is the same for individual amino acids in aqueous solution (where the molar extinction coefficient was measured) as for the amino acid in the conformational environment of the protein of interest. We demonstrate that additional considerations may be necessary for the membrane scaffold protein in dimyristoyl-phosphocholine nanodiscs through ultraviolet absorption spectroscopy of nanodiscs, liposomes, the membrane scaffold protein, and a mixture of liposomes and the non-nanodisc-associated protein. The aromatic amino acids of the membrane scaffold protein absorb significantly less light at 280 nm when associated with lipids in a lipoprotein assembly, which we plausibly attribute to an enhancement of chromophore excited-state lifetimes due to reduced intramolecular motion in the nanodisc. We caution that using the molar absorptivity of the membrane scaffold protein alone to determine nanodisc concentrations may not yield accurate results. Instead, the molar absorptivity of each nanodisc formulation should be explored independently to account for the unique conformational environment of each nanodisc.
Computing the R-matrix of the quantum toroidal algebra
Authors: Garbali Alexandr , Neguţ Andrei
Published: January 2023

We consider the problem of the R-matrix of the quantum toroidal algebra Uq,t(gl..1) in the Fock representation. Using the connection between the R-matrix R(u) (u being the spectral parameter) and the theory of Macdonald operators, we obtain explicit formulas for R(u) in the operator and matrix forms. These formulas are expressed in terms of the eigenvalues of a certain Macdonald operator, which completely describe the functional dependence of R(u) on the spectral parameter u. We then consider the geometric R-matrix (obtained from the theory of K-theoretic stable bases on moduli spaces of framed sheaves), which is expected to coincide with R(u) and thus gives another approach to the study of the poles of the R-matrix as a function of u.
Sheath formation mechanism in collisional electronegative warm plasma with two-temperature non-extensive distributed electrons and ionization
Authors: Dhawan Rajat , Malik Hitendra K.
Published: January 2023

The sheath formation mechanism is modeled in a four-component collisional electronegative warm plasma considering the behavior of positive ions by fluid equations and of negative ions by the Boltzmann distribution, along with non-extensive distributions of hot and cold electrons. For a more realistic situation, the ion source term and the ionization rate are also included in the basic equations that are solved numerically by applying appropriate boundary conditions. A concept of sheath thickness measurement is established based on two approaches, namely, the zero-electron-density approach and the floating potential approach. An identical behavior of the sheath thickness is observed based on these approaches, which means that the floating potential approach confirms the efficacy of the zero-electron-density approach. Finally, the effects of various parameters such as the temperature of all the plasma species, collisions, ionization rate, and non-extensivity are evaluated on the profiles of the densities of plasma species, electric potential, and net space charge density for better understanding of the sheath formation mechanism. In comparison to electropositive plasma, a sharp fall in the potential for the case of electronegative plasma has been depicted, or in other words, higher potential gradient is realized in the electronegative plasma. Also, increasing negative ion temperature results in the reduced sheath thickness and produces a stronger gradient in the potential.
Excitonic luminescence of iodine-intercalated HfS2
Authors: Zawadzka N. , Woźniak T. , Strawski M. , Antoniazzi I. , Grzeszczyk M. , Olkowska-Pucko K. , Muhammad Z. , Ibanez J. , Zhao W. , Jadczak J. , Stępniewski R. , Babiński A. , Molas M. R.
Published: January 2023

Photoluminescence from bulk HfS2 grown by the chemical vapor transport method is reported. A series of emission lines is apparent at low temperature in the energy range of 1.4–1.5 eV. Two groups of the observed excitonic transitions followed by their replicas involving acoustic and optical phonons are distinguished using classical intensity correlation analysis. The emission is attributed to the recombination of excitons bound to iodine (I2) molecules intercalated between layers of HfS2. The I2 molecules are introduced to the crystal during the growth as halogen transport agents in the growth process. Their presence in the crystal is confirmed by secondary ion mass spectroscopy.
A low-power reconfigurable memristor for artificial neurons and synapses
Authors: Yan Xiaobing , Shao Yiduo , Fang Ziliang , Han Xu , Zhang Zixuan , Niu Jiangzhen , Sun Jiameng , Zhang YinXing , Wang Lulu , Jia Xiaotong , Zhao Zhen , Guo Zhenqiang
Published: January 2023

With the advancement of artificial intelligence technology, memristors have aroused the interest of researchers because they can realize a variety of biological functions, good scalability, and high running speed. In this work, the amorphous semiconductor material silicon carbide (SiC) was used as the dielectric to fabricate the memristor with the Ag/SiC/n-Si structure. The device has a power consumption as low as 3.4 pJ, a switching ratio of up to 105, and a lower set voltage of 1.26 V, indicating excellent performance. Importantly, by adjusting the current compliance, the strength of the formed filaments changes, and the threshold characteristic and bipolar resistance switching phenomenon could be simultaneously realized in one device. On this basis, the biological long- and short-term memory process was simulated. Importantly, we have implemented leakage integration and fire models constructed based on structured Ag/SiC/n-Si memristor circuits. This low-power reconfigurable device opens up the possibilities for memristor-based applications combining artificial neurons and synapses.
Graphene-assisted low temperature growth of nearly single-crystalline GaN thin films via plasma-enhanced atomic layer deposition
Authors: He Yingfeng , Song Yimeng , Wei Huiyun , Qiu Peng , Liu Heng , Zhu Xiaoli , Tian Feng , Peng Mingzeng , Zheng Xinhe
Published: January 2023

Direct growth of gallium nitride (GaN) thin films is performed using plasma-enhanced atomic layer deposition (PEALD) at 300 °C on a sapphire with a graphene interlayer. The x-ray diffraction and spherical aberration corrected transmission microscope results confirm that the GaN thin films are nearly single-crystalline. Additionally, the interfacial properties and nucleation behaviors of the GaN thin films deposited on graphene are investigated in detail. Therefore, this study offers a perspective on PEALD growth of high-quality nanoscale GaN epilayers and broadens the choice for low-temperature fabrication of GaN based-devices.
Growth dominated crystallization of GeTe mushroom cells during partial SET operation
Authors: Yu Yiqi , Skowronski Marek
Published: January 2023

Phase change memory devices are a leading candidate for non-volatile memory arrays, as artificial synapses in neuromorphic circuits, and for in-memory computing. These applications are hampered by a large cycle-to-cycle variation of resistance that is likely associated with the crystallization mechanism of phase change materials. This work presents a direct observation by transmission electron microscopy of the crystallization process during the SET operation of the GeTe 100 nm mushroom cell. The process proceeded purely by growth from the periphery of the amorphous dome without nucleation. It is invariably associated with partial melting of the GeTe layer. The growth-dominated SET operation can completely crystallize the GeTe functional layer only by a gradual sweep down of the voltage across the device. The experimental results were correlated with a finite element model of heat and charge flow and the crystallization dynamics.
Metal-carbon nanotube composite for wavelength-selective bolometer with improved characteristics
Authors: Nandi Sukanta , Panwar Vinod , Misra Abha
Published: January 2023

This work comprehensively discusses the utilization of a metal-multiwalled carbon nanotube (CNT) nanocomposite of gold (Au)/CNT for uncooled bolometric application synthesized by a simple rapid green synthesis technique. Enhanced light–matter interaction with the visible (532 nm) and near-infrared (1064 nm) radiations in the nanocomposite is utilized for achieving improved bolometric response at room temperature (RT, ∼300 K). A comparatively higher temperature coefficient of resistance of ∼−0.11%/K (improvement of ∼57%) was achieved in the Au/CNT nanocomposite bolometer (BM). Additionally, the composite BM demonstrated a dual (532 and 1064 nm) spectral selectively and enhanced sensitivity with respective large RT voltage responsivities of ∼11.70 ± 3.45 V/W and ∼503.54 ± 12.77 mV/W, as opposed to null response from the CNT BM. The current study, thus, demonstrates an important step toward designing high-performing CNT BMs for uncooled operation, with added functionality of wavelength-selectiveness.
Jewels from chaos: A fascinating journey from abstract forms to physical objects
Authors: Bertacchini Francesca , Pantano Pietro S. , Bilotta Eleonora
Published: January 2023

An intellectual journey that began with the discovery of strange attractors derived from Chua's circuit, their translation into physical shapes by means of 3D printers, and finally, to the production of jewelry is presented. After giving the mathematical characteristics of Chua's circuit, we explain the chaotic design process, used for creating jewels, providing specifications of the used methodological approach, for its reproduction. We discuss the feasibility of this approach and the transmission of scientific contents on chaos theory, usually restricted to university students, in a high school Science, Technology, Engineering, Art, and Mathematics course, for the realization of advanced educational processes, implemented both in computational and real environments. We think that the idea of transforming science into art forms can drive students in acquiring scientific knowledge and skills, allowing them to discover the inner beauty of chaos.
Self-consistent implementation of locally scaled self-interaction-correction method
Authors: Yamamoto Yoh , Baruah Tunna , Chang Po-Hao , Romero Selim , Zope Rajendra R.
Published: January 2023

Recently proposed local self-interaction correction (LSIC) method [Zope et al., J. Chem. Phys. 151, 214108 (2019)] is a one-electron self-interaction-correction (SIC) method that uses an iso-orbital indicator to apply the SIC at each point in space by scaling the exchange–correlation and Coulomb energy densities. The LSIC method is exact for the one-electron densities, also recovers the uniform electron gas limit of the uncorrected density functional approximation, and reduces to the well-known Perdew–Zunger SIC (PZSIC) method as a special case. This article presents the self-consistent implementation of the LSIC method using the ratio of Weizsäcker and Kohn–Sham kinetic energy densities as an iso-orbital indicator. The atomic forces as well as the forces on the Fermi-Löwdin orbitals are also implemented for the LSIC energy functional. Results show that LSIC with the simplest local spin density functional predicts atomization energies of the AE6 dataset better than some of the most widely used generalized-gradient-approximation (GGA) functional [e.g., Perdew–Burke–Ernzerhof (PBE)] and barrier heights of the BH6 database better than some of the most widely used hybrid functionals (e.g., PBE0 and B3LYP). The LSIC method [a mean absolute error (MAE) of 0.008 Å] predicts bond lengths of a small set of molecules better than the PZSIC-LSDA (MAE 0.042 Å) and LSDA (0.011 Å). This work shows that accurate results can be obtained from the simplest density functional by removing the self-interaction-errors using an appropriately designed SIC method.
Emerging multi-frequency surface strain force microscopy
Authors: Zeng Qibin , Sim Celine , Yong Anna Marie , Hui Hui Kim , Chen Yunjie , Zhang Lei , Tan Chee Kiang Ivan , Liu Huajun , Zeng Kaiyang
Published: January 2023

During the past decade, Scanning Probe Microscopy (SPM) based surface strain detection techniques have been extensively used in the characterization of functional materials, structures, and devices. Here, we refer these techniques as Surface Strain Force Microscopy (SSFM), which mainly includes the Piezoresponse Force Microscopy, Atomic Force Acoustic Microscopy, Atomic Force Microscopy-Infrared spectroscopy (or photothermal induced resonance), Piezomagnetic Force Microscopy, and Scanning Joule Expansion Microscopy. The inception of SSFM opens up a pathway to study the nanoscale physical properties by using a sharp tip to detect the local field-induced surface strain. Through measuring the signals of the surface strain, multiple physical properties, such as the electromechanical, mechanical, photothermal, magnetic, thermoelastic properties, can be characterized with an unprecedented spatial resolution. In order to further develop and overcome the fundamental issues and limitations of the SSFM, the multi-frequency SPM technology has been introduced to the SSFM-based techniques, leading to the emerging of multi-frequency SSFM (MF-SSFM). As a technical breakthrough of the SSFM, MF-SSFM has demonstrated substantial improvements in both performance and capability, resulting in increased attentions and numerous developments in recent years. This Perspective is, therefore, aimed at providing a preliminary summary and systematic understanding for the emerging MF-SSFM technology. We will first introduce the basic principles of conventional SSFM and multi-frequency SPM techniques, followed by a detailed discussion about the existing MF-SSFM techniques. MF-SSFM will play an increasingly important role in future nanoscale characterization of the physical properties. As a result, many more advanced and complex MF-SSFM systems are expected in the coming years.
GaN damage-free cyclic etching by sequential exposure to Cl2 plasma and Ar plasma with low Ar+-ion energy at substrate temperature of 400 °C
Authors: Nakamura Shohei , Tanide Atsushi , Kimura Takahiro , Nadahara Soichi , Ishikawa Kenji , Oda Osamu , Hori Masaru
Published: January 2023

Damage-free atomic layer etching (ALE) of GaN was demonstrated using a cyclic process in which the chlorinated layer formed by Cl2 plasma exposure was removed by exposure to Ar plasma with energy-controlled ions when the substrate temperature was maintained at 400 °C. The layer chlorinated at 400 °C by Cl2 plasma exposure was found to be thinner than that chlorinated at 25 °C. Therefore, in the case of an Ar+-ion energy of 70 eV, the “ALE synergy” parameter, which quantifies the degree to which a process approaches the ideal ALE regime, decreased from 86% at a substrate temperature of 25 °C to 24% at a substrate temperature of 400 °C. A substrate temperature of 400 °C promoted etching even at the lower ion energy of 40 eV, thereby resulting in a higher ALE synergy of 62%. The vertical etching profile with no degradation of photoluminescence near the band edge on the etched surface was then observed. The proposed high-temperature ALE method is promising for realizing a vertical pattern profile via damage-free etching of GaN.
Effects of non-uniform elbow inflow on the unsteady flow and energy development characteristics of a centrifugal pump
Authors: Yuan Ye , Fang Yujian , Tang Lingdi
Published: January 2023

A non-uniform inflow caused by an elbow structure is one of the main reasons for the low energy transformation efficiency of a centrifugal pump. Prototype experiments for the centrifugal pump are used to analyze the transformation rule of pump energy characteristics under the uniform inflow and non-uniform elbow inflow. The non-uniform elbow inflow increases the hydraulic losses in the centrifugal pump to reduce the pump head and operation efficiency. The pump efficiency decreases by 8% under the design flow condition. The large eddy simulation with a shear-modified eddy viscosity model is applied to simulating flow excitation characteristics and energy development features. The non-uniform inflow increases the impact loss at an impeller inlet and produces unsteady flow excitation in the impeller passage. The elbow inflow affects the pressure fluctuation frequency, and the main frequency is twice the blade-passing frequency (250 Hz). The high entropy production regions are mainly concentrated at the suction surface of the blade and the interface of impeller and volute, coinciding with the unsteady flow areas in the pump. The asymmetrical entropy yield distribution in the elbow inflow pump is intensified because of the increase in the flow loss caused by the non-uniform inflow.
A real-time phase processing system for phase sensitive optical time domain reflectometer
Authors: Zhou Fan , Cao Zhe , Ge Qishuai , Zhang Qiang , Zhao Dongfeng , Liu Shubin , Chen Yang
Published: January 2023

In order to improve the real-time performance of a phase-sensitive optical-time-domain reflectometer (Φ-OTDR), a fully digital phase processing system is demonstrated. Using digital down-conversion and field programmable gate array (FPGA) hardware calculation, the phase of the Rayleigh scattering light can be demodulated in real-time. Benefiting from the pipeline calculation in the FPGA, the real-time performance of this system is not affected by the interrogation rate and fiber sensing distance. Experiments show that this real-time detection system has the same vibration detection performance as an offline data process and has good stability. The dynamic strain sensing with a sensing distance of 50 km, an interrogation rate of 1 kHz, and a spatial sampling interval of 1 m is experimentally demonstrated. The obtained results indicate that the fully digital signal processing system can ensure the real-time detection of Φ-OTDR under the condition of long distance and high resolution.
Voltage modulated long-term plasticity in perovskite heterostructured memristive synaptic devices with high-performance neuromorphic computing
Authors: Zhang Jianxing , Li Hangfei , Liu Tao , Dong Shijie , Xu Sheng , Li Hailian , Su Jie
Published: January 2023

The development of neuromorphic computing is expected to enable the computer to realize the integration of storage and computation. The development of memristors provides hardware support possibilities for the development of neuromorphic computing. In this work, we have prepared a (La0.67, Sr0.33)MnO3/BaTiO3-based memristor with good forward and reverse memristor function and multilevel resistive tunability, including an increased resistance state at forward voltage and a decreased resistance state at reverse voltage. This is mainly due to the barriers of the ferroelectric dielectric layer and its ferroelectric polarization under the electric field, and the migration of oxygen vacancy under the electric field. The devices also successfully implement the synaptic simulations of short-term plasticity, long-term plasticity, excitatory postsynaptic current, paired-pulse facilitation, spike-rate-dependent plasticity, and spike-timing-dependent plasticity and reimplement these synaptic simulations by varying the amplitude and pulse width of the applied voltage. We have also achieved a classification accuracy of 96.7% for the given handwritten digit data by an artificial neural network with supervised learning. The high classification accuracy is attributed to the good nonlinearity of the device in terms of continuous conductance decreased (0.91) and increased (0.58). Our results are expected to provide a good reference value for neural devices.
Rovibrational internal energy transfer and dissociation of high-temperature oxygen mixture
Authors: Jo Sung Min , Venturi Simone , Kim Jae Gang , Panesi Marco
Published: January 2023

This work constructs a rovibrational state-to-state model for the O2 + O2 system leveraging high-fidelity potential energy surfaces and quasi-classical trajectory calculations. The model is used to investigate internal energy transfer and nonequilibrium reactive processes in a dissociating environment using a master equation approach, whereby the kinetics of each internal rovibrational state is explicitly computed. To cope with the exponentially large number of elementary processes that characterize reactive bimolecular collisions, the internal states of the collision partner are assumed to follow a Boltzmann distribution at a prescribed internal temperature. This procedure makes the problem tractable, reducing the computational cost to a comparable scale with the O2 + O system. The constructed rovibrational-specific kinetic database covers the temperature range of 7500–20 000 K. The reaction rate coefficients included in the database are parameterized in the function of kinetic and internal temperatures. Analysis of the energy transfer and dissociation process in isochoric and isothermal conditions reveals that significant departure from the equilibrium Boltzmann distribution occurs during the energy transfer and dissociation phase. Comparing the population distribution of the O2 molecules against the O2 + O case demonstrates a more significant extent of nonequilibrium characterized by a more diffuse distribution whereby the vibrational strands are more clearly identifiable. This is partly due to less efficient mixing of the rovibrational states, which results in more diffuse rovibrational distributions in the quasi-steady-state distribution of O2 + O2. A master equation analysis for the combined O2 + O and O2 + O2 system reveals that the O2 + O2 system governs the early stage of energy transfer, whereas the O2 + O system takes control of the dissociation dynamics. The findings of the present work will provide a strong physical foundation that can be exploited to construct an improved reduced-order model for oxygen chemistry.
Spin-torque oscillator with coupled out-of-plane oscillation layers for microwave-assisted magnetic recording: Experimental, analytical, and numerical studies
Authors: Nakagawa Yuji , Takagishi Masayuki , Narita Naoyuki , Nagasawa Tazumi , Koizumi Gaku , Chen Wenyu , Kawasaki Shohei , Roppongi Tetsuya , Takeo Akihiko , Maeda Tomoyuki
Published: January 2023

Spin-torque oscillators (STOs) are unique spintronic devices in which spin current induces the precession of magnetization in the oscillation layer. In this study, we demonstrate coupled out-of-plane oscillation between two oscillation layers within an STO. The coupled oscillation state is observed in the magnetoresistance spectra as well as its degradation due to the mixing of the free oscillation state depending on the bias current. These behaviors are analytically described and numerically reproduced based on the Landau–Lifshitz–Gilbert equation. Since the STO is fabricated in the write head of a hard disk drive, the coupled oscillation state and the subsequent microwave magnetic field are applicable for microwave-assisted magnetic recording for high-density recording.