bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of improving oil recovery in polymer area by expanding swept volume
Authors: Zou Lipeng
Published: May 2021

In order to realize the development effect of the new K1 polymer flooding block in T oilfield, meet the recovery ratio not lower than that of the old test area and the small well spacing area, and reach or exceed the established development goal of the salt-resistant test area, it is necessary to expand the swept volume technology research. Through the research and application of a series of swept volume expansion technologies, such as high concentration and low speed stage parameters of different types of well groups, application of concentration reduction and speed increase, injection modification and deep profile control, the oil recovery is enhanced. At the stage of high concentration and low speed injection, the suitable injection concentrations of ABCD-IV wells are 1800mg/L-2100mg/L, 1500mg/L-1800mg/L, 1200mg/L-1500mg/L and 1200mg/L and below respectively. Based on the inflection point pressure of the indicator curve during water injection, after the pressure limit of concentration reduction and speed increase is determined to be 8.0MPa, the ratio of liquid absorption thickness before and after the measures and the relative liquid absorption of thin and poor layers show a trend of rising first and then falling; According to the pressure rising space, the injection pressure of all kinds of wells has decreased and the water absorption profile has been improved, and the effect of C and D wells is better than that of A and B; Seen from the drop of apparent water absorption index, the increase of liquid absorption thickness, the maximum water cut drop of connected production wells and the cumulative oil increase of single well, the effect of deep adjustment is the best in blank water drive period, followed by water cut drop period and poor in water cut recovery period.
Research Progress on Structure and Property of Hybrid Organic-Inorganic Perovskite
Authors: Liu Yaodong
Published: May 2021

This research briefly introduces the research background, structure, properties and application fields of perovskite, and reviews the research progress of hybrid organic-inorganic perovskite in recent years. The effects of crystal structure and organic cations on the stability, thermal conductivity, carrier mobility and optical and electrical properties of the hybrid perovskite are summarized, with which the importance of controlled crystal growth is highlighted and the current preparation methods and new preparation processes of perovskite materials are concluded. Finally, a prospection of perovskite materials and their applications is put forward, which provides a theoretical understanding for new perovskite materials with better crystal growth and crystal face control in the future, so as to promote the development of perovskite solar cells, light energy devices and other related fields.
Mineral Economic Regionalization in the Context of Resource Crisis and Sustained Economic Growth
Authors: Song Meng , Liu Baoshun , Zhang Junyu , Keqing Li
Published: May 2021

As mineral resources are the material basis of social and economic development, the study on the correlation between the mineral resource industry and the regional economy, which aims at a scientific division of economic zones and a clear understanding of industrial characteristics, is crucial in addressing issues related to the management of resources and economy such as regional industrial development and territorial and spatial planning. By discussing the relation between dependence on mineral resources and national economy development, this study divides the Chinese mainland into three resource-based regions, nine resource-assisted regions and 19 non-resource-based regions based on quantified regional differences underpinned by the theory of threshold effects for measurement data. Furthermore, policy recommendations are proposed to pave the path for differentiated regional development after considering multiple factors including features of regional economy and resource potential. In addition to better serving and supporting economic development, territorial and spatial planning and the strategy of mineral resources, such recommendations are expected to provide differentiated development strategies for different types of regions.
The Optimal Operation Model of Electric-Thermal-Gas Integrated Energy System Considering Multi-Energy Complementarity
Authors: Zhao Ailin , Ma Jiaxin , Zhou Xichao , Cong Lin , Bai Baohua , Zeng Ming , Zhang Xiaochun
Published: May 2021

As China’s environment and climate problems become more and more serious, the integrated energy system is booming. However, the coupling between various systems is not strong, and it is urgent to increase the coupling between multiple systems. Taking the total cost of the integrated energy system as the objective function, the independent operation and coupling transformation of the power system, natural gas system and thermal system within the system are considered. In this paper, a system planning model is built to meet the three types of loads in the system: electric load, thermal load and gas load, so as to increase the coupling of the system, ensure the reliable operation of the integrated energy system and improve the energy utilization efficiency.
Analysis of Combined Participation of Wind Power and Electric Heating in Power Supply System
Authors: Sun Yong , Li Yutian , Liu Xin , Zeng Ming , Liu Chang
Published: May 2021

In order to improve the serious situation of wind abandonment in the “Three North” areas, solve the problem of local consumption of large-scale wind power and improve the peak shaving capacity of power grid, this paper combines regenerative electric heating with wind power with anti-peak shaving characteristics, and analyses the benefits of power side and load side under the combined operation mode of wind power and regenerative electric heating from two aspects of cost and benefit. The analysis results show that the joint participation of wind power and electric heating in the power market can effectively “cut valley and fill peak” and promote wind power consumption. The benefit analysis theory proposed in this paper provides guidance for the research of joint operation scheduling optimization model.
Assessment of the External Insulation Performance of Post Insulator in Rain: A Review
Authors: Qiao Xin
Published: May 2021

In recent years, the surface discharge of polluted post insulators in rain which affects HVDC transmission has brought great influence to the national economy and people’s daily life. In order to improve the strength of the external insulation of HVDC converter stations, this paper mainly focus on the environmental characteristics and areal rainfall of UHV power stations, analyzes the influence of experimental factors (sample treatment mode, rain-drenching mode, pressurization mode and insulation material) on the discharge behavior of post insulators in rain flash experiment, summarizes the relevant standards in the rain flash experiment of large-scals post insulators. The results showed that the effects of different contamination methods on rain flashover are not different, among which spraying method can improve the experimental efficiency, and the quantitative brushing method can reach the specified ash density and salt density more easily; The number and length of water column of composite insulators are lower than that of porcelain insulators, and the number of water droplets between large sheds and the number of water droplets on the edge of large sheds are higher than that of porcelain insulators.
Research progress of high performance cathode materials for lithium-sulfur batteries
Authors: Zhang Xiang
Published: May 2021

Lithium-sulfur battery is supposed to be a key for the next generation of energy storage devices due to its advantages of high energy density, high theoretical specific capacity, low cost and environmental friendliness, and has attracted extensive attention from researchers. However, the intermediate products of lithium-sulfur batteries are easily dissolved in the electrolyte to produce shuttle effect. In addition, there is volume expansion, low inherent conductivity, slow dynamics and other factors, which limit its commercial application. This paper describes the working principle of lithium-sulfur batteries, reviews the current research status of lithium-sulfur battery cathode materials, analyzes the existing problems of lithium-sulfur batteries, summarizes the improvement methods of cathode materials, and prospects the future development direction of lithium-sulfur batteries.
Prospects of Air Conditioning Condensate Recovery and Utilization Technology
Authors: NanNan Li , Li Jie
Published: May 2021

As an excellent indoor environment conditioning equipment, air conditioners have been used on a large scale since they were listed. However, with the popularization of air conditioners, many discharged condensed water has caused many problems such as waste of resources and environmental pollution. Therefore, it is imperative to recover and use condensed water. Generally speaking, air or atmosphere is humid air, mainly composed of dry air and water vapor. This paper introduces the feasibility of recycling air-conditioning condensate water as irrigation and green water through theoretical research and analysis. Based on the formation process of condensate, through theoretical analysis and calculation, it is concluded that condensate has the three characteristics of higher water quality, lower temperature and considerable water volume. The advantages of the two condensate recovery technologies of open recovery and closed recovery are dialectically analyzed. Disadvantages, the primary utilization method of condensate water “as a water resource” is systematically explained. A particular scientific outlook is made for the future recycling and utilization technology of air-conditioning condensate water.
Research of New Pollutant Microplastics in Soil
Authors: Yan Li , Peng Wang
Published: May 2021

Microplastic pollution is one of the key new pollutants to be controlled in ecological environment protection. This article describes in detail the abundance and distribution of microplastics in the soil, their sources and access routes. It focuses on the analysis of the accumulation, migration, and degradation of microplastics in the soil, as well as the interaction with metal and organic pollutants and their environmental effects; expounds the impact of microplastics on soil organisms and soil quality and ecological risks and discuss the exposure pathways and potential human health risks of microplastics in the soil are discussed. Finally, the future direction and focus of the research on microplastics in the soil environment are prospected. It is expected to provide information and scientific guidance for a comprehensive understanding of the present and future of soil environmental microplastics research.
Discrete Element Modelling of the dynamics of a Self-Rotating Object in dense Granular Media
Authors: Liu Ping , Zou Xuan , zhou Jingyuan , Tang Wenhui , Ran Xianwen
Published: May 2021

Many reptiles can move significant distances through sand or many seeds drill out soil during germination by rotating their bodies. Inspired by the biological behaviour and challenged by the absence of physical mechanism for the locomotion in granular materials, we developed a numerical study of a self-excited spherical intruder in a granular bed under gravity, using discrete element method. In simulation, the intruder was rotated around x-axis with different friction coefficient μ and rotation angular velocity ω. We find that the space motion of intruder is sensitive to these two parameters. It moves farther in the Z+ direction with the increase of μ and ω. and there emerges opposite movement in the Y direction with the change of ω. We analysed the physical mechanisms governing these motions and proposed two qualitative theory: the tangential force raises with the increase of ω. which causes the intruder to lift faster; the competition mechanism between friction effect and squeezing effect leads to the motion differentiation of intruder in the Y direction. These results of this study pave the way for the design of an efficient bio-inspired robot moving within seabed or desert according to this mode of locomotion.
Research on the Insulation Performance of New Environmentally Friendly Insulation Gas Hexafluoropropylene and Carbon Dioxide Mixed Gas
Authors: Sun DongWei , Zhou Yongyan , Nian Tang , Li Li
Published: May 2021

Sulfur hexafluoride (SF6) gas is widely used as a gas insulation medium in medium and high voltage arc extinguishing or insulated electrical equipment, but the gas is a serious greenhouse effect gas and poses a great threat to the environment. This paper introduces a new environmentally friendly insulating gas of hexafluoropropylene (1-C3F6) with the liquefaction temperature of -29.4°C and the global warming potential (GWP) equivalent to CO2, and especially investigates its saturation vapor pressure characteristics and insulation performance. Under different electrode structures and voltage characteristics, the insulation characteristics of the 1-C3F6/CO2 gas mixture were studied by changing the electrode distance and the pressure of gas mixture.
Microbiological Community Analysis of the Composting of Poplar Processing Residues
Authors: Liang Xiaohui , Si Hongyu , Fan Yuben , Wang Bing , Hua Dongliang , Wang Zhixin , Dong Chengwen
Published: May 2021

In this study, poplar processing residues was used as the sole substrate for composting, and the microbiological communities such as fungi and bacteria were analysed. Two most favourable fungal phyla Ascomycetes and Basidiomycetes and five kinds of fungal genus such as Aspergillus, Thermomyces, Rhizomucor, Rhizopus, Myceliophthora were mainly distributed (more than 80%) in the high temperature samples. As for the bacteria, Firmicutes, Actinobacteria and Proteobacteria were the three most advantageous phyla in the high temperature samples. At the same time, Geobacillus, Bacillus, Thermobispora and Sphingomonas were the dominant bacteria in the high temperature samples at the genus level.
Study on prevention and control technology of mineral dust discharged from high and deep chute
Authors: Zou Changfu
Published: May 2021

Based on the production process characteristics of the deep pass in Xiadian Gold Mine, a pass unloading model was established, and the dust return characteristics of pass unloading operations were simulated and studied. The dust production law of pass unloading was tested and analyzed, and it was concluded that the transient conditions of deep pass unloading are different According to the distribution of the concentration of each section at the moment, according to the flow field distribution law of the discharge port, a blow-suction airtight dust extraction and purification treatment measure is proposed, which realizes the effective dust control of the discharge surface of the chute and improves the dust extraction efficiency of the dust collector After the on-site supporting research and treatment, the total dust concentration of the chute unloading operation was reduced from 378.3mg/m3 to 5mg/m3, the dust reduction efficiency reached 98.7%, and the respirable dust concentration was reduced from 133.3mg/m3 to 3mg/m3. The efficiency is 97.7%, and the dust reduction effect is good. It solves the problem of the pollution of mineral dust unloading in the deep pass, and provides a basic basis for the treatment of metal mines.
The Effect of Water Availability on The Growth and Yield of Kumis kucing (Orthosiphon aristatus (Blume) Miq.)
Authors: Hadiyanti Nugraheni , Rahardjo Djoko , Junaidi  , Bambang Dwi Moeljanto
Published: May 2021

Kumis kucing (Orthosiphon aristatus (Blume) Miq.) is one of the medicinal plants that are economically valuable because of the secondary metabolite of sinensetin efficacious for various diseases. Growth and yield the plants are affected by environmental factors, one of which is water availability. The aim of the research was to evaluate the effect of water availability on growth and yield of kumis kucing. The design of the study was a complete randomized design with a single factor, which was water availability (100; 50; 37.5; 25 and 12.5% field capacity/FC). Data observation was analyzed by analysis of variance and followed by the Duncan Multiple Range Test at 5% upon the significant result. The result showed that the water availability 50-12.5% FC had a negative effect on plant growth, dry weight, and fresh weight of the plant, whereas the highest growth reduction occurred at 12.5% FC on height plant, leaf area, dry weight, and fresh weight of the plant. The result showed that kumis kucing is a plant that is resistant to low water availability.
Ignored but not Forgotten: The Broken Windows Tipping Point and the Question of Functional Form
Authors: De Biasi Alaina
Published: May 2021

Wilson and Kelling provide a simple instruction to address disorder: direct limited police resources to neighbourhoods at the tipping point. In doing so, they suggest that the disorder–crime relationship reflects a threshold effect. A proper test of the validity of broken windows theory should, therefore, accommodate nonlinearity. To this end, this study empirically examines the functional form of the relationship between physical disorder and violent crime rate in Detroit, MI, utilizing a dose–response propensity score methodology. This examination is aided by open-sourced data collected at the census block-group level. Findings support a nonlinear relationship, favouring a threshold effect with two caveats. Several directions for future research are explored, as well as implications for theory, practice and policy.
Shadow and Light: Online Narratives of Relationship Dissolution among Former Partners of Incarcerated Men
Authors: Umamaheswar Janani
Published: May 2021

Criminological research has explored the challenges that incarceration poses to romantic relationships, but less is known about partners who have abandoned efforts to sustain these relationships. In this article, I explore narratives of relationship dissolution among former partners of incarcerated (or formerly-incarcerated) men. Through inductive analyses of 603 posts across 23 threads on Virtual Support for Prisoners (VSP)—a pseudonymous online prisoner support forum—I describe how VSP members position their former partners as morally inferior men inhabiting dark spaces of despair, while framing themselves as harbingers of light into these spaces. These findings reveal how prisons (and people who are confined within them) influence—and are imagined by—those outside prison.
Sarcopenia and surgical outcomes in patients undergoing oncologic colonic surgery
Authors: Schneider M , Hübner M , Becce F , Koerfer J , Collinot J -A , Demartines N , Hahnloser D , Grass F , Martin D
Published: May 2021

Objective

Sarcopenia is a marker for malnutrition and frailty which could lead to higher complication rate and prolonged length of stay (LOS) after surgery. The study aim was to assess the correlation between sarcopenia and clinical outcomes in oncologic colonic surgery.

Methods

This retrospective study included consecutive patients operated between 2014 and 2019. Three radiological indices of sarcopenia were measured at the level of the third lumbar vertebra on preoperative CT scans: Skeletal Muscle Area (SMA), Skeletal Muscle Radiation Attenuation (SMRA), and Skeletal Muscle Index (SMI). Patients with major complications (> grade 3a) according to Clavien classification were compared to those without. Statistical correlation between sarcopenia indices, LOS and Comprehensive Complication Index (CCI) was tested by use of the Pearson correlation.

Results

A total of 325 patients were included, 50 (15.4%) with and 275 (84.6%) without major complications. SMA and SMI were comparable between both groups (respectively 126.0 vs 125.2 cm2, p = 0.974, and 43.4 vs 44.3 cm2/m2, p = 0.636), while SMRA was significantly lower in patients with major complications (33.6 vs 37.3 HU, p = 0.018). A lower SMRA was correlated with prolonged LOS (r=-0.207, p < 0.01) and higher CCI (r=-0.144, p < 0.01), while the other sarcopenia indices had no influence on surgical outcomes.

Conclusion

Preoperative SMRA or muscle quality appears to be a weak predictor for adverse outcomes after oncologic colectomy.
High expression of CD34 protein in stage IIA rectal cancer is independently associated with better prognosis
Authors: Lalos A , Wilhelm A , Staubli S , Posabella A , Weixler B , von Flüe M , Droeser R A , Tampakis A
Published: May 2021

Objective

Colorectal cancer (CRC) remains the third most common cause of death from malignancies, while 30% of all these tumors develop in the rectum. The proximity of the rectum to vital structures, and in some cases the use of neoadjuvant treatment, make the surgical resection of this tumor a great challenge even for highly qualified surgeons. Understanding the mechanisms of rectal cancer (RC) development could lead to new concepts in the approach of diagnosis, prognosis, and eventually treatment of this disease. Despite the fact that TNM classification represents the gold standard tool for the staging of RC, a significant number of studies has recently focused on the association between the tumor microenvironment and RC. CD34 is a transmembrane phosphoglycoprotein expressed on human hematopoietic progenitor and vascular endothelial cells, as well in malignant tissues. It has also been shown to be involved in tumor invasion and angiogenesis. Because of the controversial data , we examined the expression of CD34 protein in RC specimens after stratifying the patients according to their UICC stage.

Methods

In our retrospective study, we included 364 patients with unselected, clinically annotated primary RC specimens. We analyzed a tissue microarray (TMA) of these specimens by immunohistochemistry (IHC) for the expression of CD34 protein by tumor cells.

Results

After stratifying the patients in nodal negative and positive groups, we found that the patients with Stage IIA tumors and high expression of CD34 protein had a favorable 5-year overall survival rate (53%; 95%CI = 40.0 – 65.1%) compared to tumors without expression of CD34 protein (26%; 95%CI = 10.7 – 44.6%, p = 0.003). Univariate and multivariate Hazard Cox regression survival analysis revealed that the combined the expression of CD34 protein was an independent, favorable, prognostic marker for overall survival in the stage IIA RC (HR = 0.39, 95%CI = 0.19 – 0.79; p = 0.009).

Conclusion

Our data show that the expression of CD34 protein represents an independent, favorable, prognostic condition in nodal negative stage IIA RC. Thereby, we provide novel insights into the prognostic role of the tumor microenvironment in RC that might help in the development of novel treatment modalities by its modification.
Prospective surveillance after implementation of a colorectal surgical site infection prevention bundle
Authors: Jurt J , Clerc D , Curchod P , Hübner M , Hahnloser D , Senn L , Demartines N , Grass F
Published: May 2021

Objective

Surgical site infections (SSI) are the most frequent complications after colorectal surgery. The aim of the present study was to evaluate the impact of a standardized SSI prevention bundle.

Methods

The multimodal, evidence-based care bundle included 9 intraoperative items (antibiotic type, timing and re-dosing, desinfection, induction temperature control >36.5°, glove change, intracavity lavage, wound protection and closure strategy). The bundle was implemented in November 2018 and applied to all consecutive patients undergoing colonic resections. Demographics, surgical specifics and overall compliance to the care bundle were prospectively assessed until October 2020. The primary outcome SSI was defined according to the definition of the Center for Disease Control (CDC) and independently assessed by the National Infection Surveillance Committee (Swissnoso) up to 30 postoperative days. A historical, institutional pre-implementation control group (2012-2017, DOI: 10.1016/j.jhin.2018.09.011) with identical methodology was used for comparison.

Results

In total, 243 patients were included. The control group included 1’263 patients. Both groups were comparable regarding main demographics (age, sex, body mass index, American Society of Anaesthesiologists class) and surgical characteristics (type and duration of surgery). Overall compliance to the care bundle was 77% (IQR 77-88). Lowest compliance was observed for temperature control (48%), intracavity lavage (59%) and predefined wound closure strategy (74%). Surgical site infections were reported in 54 patients (22.2%) vs. 21.4% in the control group, p = 0.79. Infection rates were comparable throughout the CDC categories: superficial: 11 patients (4.5%) vs. 4.2%, p = 0.82, deep incisional: 9 patients (3.7%) vs. 5.1%, p = 0.34, organ space: 34 (14%) vs. 12.4%, p = 0.48.

Conclusion

Implementation of a standardized surgical care bundle had no impact on SSI rates according to these preliminary results. Improved compliance to individual measures may help to achieve a clinical benefit.
BILCAP-study: Should patients with resected biliary tract cancer really receive adjuvant chemotherapy with capecitabine?
Authors: Manzini G , Klotz U , Hines I , Henne-Bruns D , Kremer M , Kirchner M
Published: May 2021

Objective

According to the 2019 published ASCO guidelines patients with resected biliary tract cancer should be offered adjuvant capecitabine chemotherapy based solely on the results of the BILCAP trial. Aim of this work is to analyze the quality of the BILCAP trial.

Methods

Design, conduct, statistics and reporting of the study were analyzed according to the Delphi list and the CONSORT checklist. The risk of bias was assessed using the Cochrane Risk of Bias Tool.

Results

Several shortcomings could be identified in the study regarding design, conduct, statistics and reporting. The BILCAP study is a randomized, controlled, multicenter, phase 3 study which was done across 44 specialist hepatopancreatobiliary centres in the UK. Despite the inclusion of high specialized centres, the number of included patients each year for each center is extremely low. In particular, a total of 447 patients were included by 44 centers over a period of 11 years, meaning that less than 1 patient was included in this study every year by each center. However, the analysis was not adjusted for center which was one of the stratification factors. Follow up treatment for patients who had disease recurrence was not recorded. Randomization procedure is not well described. Minimization technique was adopted for stratification but mode of application is poorly reported and the choice of variables not justified. No blinding was present. Extensive power evaluations after adjusting the number of needed events, due to lower event rates than expected, were not done. For the observed HR = 0.81 with 234 events statistical power is only around 37%. 4 out of 9 items of the Delphi list and 6 out of 35 items of the CONSORT checklist were not properly addressed. According to the Cochrane Risk of Bias Tool (RoB 2) the overall risk-of-bias judgment for the outcome overall survival of the BILCAP study was “some concerns”. Almost all authors declared to have received funds from pharmaceutical companies, so a conflict of interest cannot be excluded. Additionally, the funding agency for this study (Cancer Research UK and Roche) had an advisory role in design and the first author of the BILCAP study was also involved in the generation of the ASCO guideline.

Conclusion

Based on the results of this study there is not enough evidence for the administration of adjuvant chemotherapy with capecitabine in patients with resected biliary tract cancer.
Does persistent cholecystitis after cholecystostomy increase mortality?
Authors: Hess G F , Staubli S M , Muenst S , Bolli M , Zech C J , Hoffmann M , von Flüe M , Kollmar O , Soysal S D
Published: May 2021

Objective

Numerous publications describe percutaneous cholecystostomy (PC) as a possible treatment option for acute cholecystitis (AC) in selected cases where laparoscopic or open cholecystectomy (CHE) is not feasible due to limited health conditions. Whereas certain experts propose PC as a definitive therapy option for AC, a number of studies question the use of PC, due to high complication rates, no additional benefit of PC compared to CHE, and an increased mortality. The aim of our study was to retrospectively analyze the outcome of patients treated with PC over an extended period of time.

Methods

We conducted a retrospective study of patients who underwent PC for AC at a tertiary referral hospital during the last 10 years. The collected data included basic demographics, details about PC procedure, outcome, surgical-rate and final histologic diagnosis.

Results

Out of 158 patients (median age 75 years) treated with PC for AC, 47 (30%) died without undergoing subsequent CHE. Half of the PC patients (79) underwent subsequent CHE (8% in the hot phase), with 97% of these patients undergoing subsequent CHE within one year after PC. Seven (5%) of them died within the first year. The overall Charlson Comorbidity Index (CCI) was 6.4 (CHE vs. no CHE 5.3 vs. 7.4). Histologically, 22 (29%) of the 75 analyzed specimens showed chronic cholecystitis (CC), and 57 patients (68%) had signs of an AC. In 48 patients (30%), a complication after PC occurred.

Conclusion

In our collective, the 1-year survival after PC was 72%. The majority of these patients were in limited health conditions with a mean pre-PC CCI > 5, which implies a potential one-year mortality rate of over 85%. Histologic examination of almost all cholecystectomy specimens showed persistent inflammation. To our knowledge, this is the first extensive report of histologic findings in gallbladder specimens after PC.

Based on our findings, especially in view of the high mortality rate of PC patients, we propose CHE as the treatment of choice in AC, even in chronically ill and elderly patients after stabilization, e.g. with a PC. PC represents no definitive treatment for AC and should remain a short-term solution because of the persistent inflammatory focus. Because CHE in a critically ill patient can be challenging, it should be performed by the most experienced surgeons.
Comparison of long-term survivals following hepatectomy for hepatocellular carcinoma according to the time-point of recurrence and treatment modalities for recurrent disease
Authors: Di Pietro Martinelli C , Andreou A , Gloor S , Lachenmayer A , Kim-Fuchs C , Dufour J -F , Beldi G , Candinas D , Banz V
Published: May 2021

Objective

Disease recurrence following curatively intended hepatectomy for hepatocellular carcinoma (HCC) limits oncologic outcome. Based on the extent, location and time-point of tumor recurrence, different therapeutic modalities are available to treat recurrent HCC. Therefore, our aim was to investigate the role of these treatments and the time-point of recurrence on long-term survival.

Methods

Clinicopathological data of patients, who underwent hepatectomy for HCC at a major hepatobiliary center in Switzerland between 2012 and 2019, were assessed. Patients suffering tumor recurrence were stratified according to the treatment modalities for recurrent HCC including surgical treatment (repeat hepatectomy or liver transplantation), interventional treatment, and conservative treatment (chemotherapy or best supportive care). Groups were compared regarding to overall survival (OS). Additionally, long-term outcomes were compared between patients with early (≤ 12 months) and late (> 12 months) tumor recurrence.

Results

During the study period, 159 patients underwent hepatectomy for HCC. Median follow-up time was 53 months. After a median time of seven (1-64) months, 74 patients were diagnosed with tumor recurrence (47 %). The majority of patients developed early recurrence (n = 49) and 58 patients had intrahepatic recurrence only. Treatment options were re-resection, liver transplantation, interventional methods, and palliative therapy in 5, 15, 23, and 31 patients, respectively. Surgical treatment was significantly associated with improved OS compared to interventional and conservative treatment (5-year OS: 84% vs. 39% vs. 30%, p < 0.0001). OS was significantly better among patients with late recurrence compared to patients with early recurrence, irrespective of the treatment modality used for the recurrent disease (5-year OS: 70% vs. 38%, p = 0.008).

Conclusion

Repeat hepatectomy or liver transplantation for recurrent HCC following hepatectomy is associated with better long-term survival compared to interventional or conservative therapies, especially for patients with late tumor recurrence. Patients with intrahepatic HCC recurrence should be evaluated according to the extent of tumor burden, liver function, and functional status to identify the best candidates for a surgical treatment.
Individual patient data meta-analysis of delayed gastric emptying after pylorus-preserving versus pylorus-resecting pancreatoduodenectomy
Authors: Probst P , Klaiber U , Seide S , Kawai M , Matsumoto I , Strobel O , Hackert T , Büchler M W , Diener M K
Published: May 2021

Objective

Some studies have indicated that resecting the pylorus during partial pancreatoduodenectomy (PD) may lead to reduced delayed gastric emptying (DGE). Randomized controlled trials (RCTs) showed conflicting results regarding superiority of pylorus-resecting PD (prPD) compared to the pylorus-preserving procedure (ppPD). The aim of this individual patient data meta-analysis was to investigate risk factors on an individual patient level which may explain the observed differences between the existing RCTs.

Methods

RCTs comparing ppPD and prPD were searched systematically in MEDLINE, Web of Science and CENTRAL. Individual patient data (IPD) from existing RCTs were included. The primary endpoint was DGE according to the International Study Group of Pancreatic Surgery (ISGPS) adjusted for age, sex and body-mass-index (BMI). The meta-regression model was applied to the IPD of the RCTs. Mixed effects models were applied to perform meta-analyses.

Results

IPD from 418 patients (three RCTs) were used for quantitative synthesis. There was no significant statistical difference between ppPD and prPD regarding DGE adjusted for age, sex and BMI (OR 0.72; 95%-CI: 0.41 to 1.22) and DGE grade (RR 1.01; 95%-CI: 0.64 to 1.57). Regarding other relevant perioperative and postoperative outcome parameters, there were also no significant differences among the two techniques.

Conclusion

This IPD meta-analysis comparing preservation and resection of the pylorus during PD confirmed that the resection of the pylorus is not superior to the pylorus-preserving procedure regarding DGE. The pylorus should therefore be preserved whenever possible. Further RCT are futile, because their results are unlikely to change the pooled estimate for DGE.
Trocar site closure with a novel anchor-based (neoClose®) system versus standard suture closure: A prospective randomized controlled trial
Authors: Iranmanesh P , Bajwa K , Snyder B , Wilson T , Chandwani K , Shah S , Wilson E
Published: May 2021

Objective

Patients with obesity have a higher risk of trocar site hernia. The objective of the present study was to compare a standard suture passer versus the neoClose® device for port site fascial closure in patients with obesity undergoing laparoscopic bariatric surgery.

Methods

This is a randomized, controlled trial with two parallel arms. Thirty five patients with BMI ≥ 35 kg/m2 and undergoing laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass were randomized to each group. Port site fascial closure for trocars ≥ 10 mm was performed with the neoClose® device in the study group and the standard suture passer in the control group. Primary outcomes were time required to complete closure and intensity of postoperative pain at the fascial closure sites. Secondary outcomes were intraabdominal needle depth and incidence of trocar site hernia.

Results

The use of the neoClose® device resulted in shorter closure times (20.2 vs 30.0 s, p = 0.0002), less pain (0.3 vs 0.9, p = 0.002) at port closure sites, and decreased needle depth (3.3 cm vs 5.2 cm, p < 0.0001) compared to the standard suture passer. There was no trocar site hernia at the one-year follow-up in either group.

Conclusion

Use of the neoClose® device resulted in faster fascial closure times, decreased intraoperative needle depth, and decreased postoperative abdominal pain at 1 week as compared to the standard suture passer. These data need to be confirmed on larger cohorts of patients with longer follow-up, especially in terms of long-term hernia recurrence rates.
Performing total extraperitoneal inguinal hernia repair in patients with previous abdominal surgery is safe: an analysis of 1591 patients
Authors: Merker H , Slieker J , Soppe S , Keerl A , Nocito A
Published: May 2021

Objective

The safety of endoscopic total extraperitoneal inguinal hernia repair (TEP) in patients who previously underwent open lower abdominal surgery has been discussed for many years, since operative difficulties can be expected due to adhesions and scarring. Some research has been done in this area, most of which ask for further studies to be conducted. The aim of this study was to assess the safety and feasibility of TEP in patients with previous lower abdominal surgery (PLAS).

Methods

We retrospectively analysed all patients who underwent a TEP inguinal hernia repair at our institution between July 2012 and May 2018. Previous lower abdominal surgery (PLAS) was defined as any previous open surgery with scarring below the umbilicus. In case of scars outside the midline, these were defined as PLAS when on the same side as the operated inguinal hernia. A univariate analysis as well as logistic regression were performed to identify outcomes of surgery between patients with- and without PLAS.

Results

In total 1591 patients were included in the study. 274 patients had PLAS, corresponding to 17.2%. Comparing to patients without PLAS, the group with PLAS had a significant higher risk of increased operation duration (odds ratio 1.07, p-value 0.004), but no increased risk of conversion, or intra- or postoperative complications. The highest significant risk of increasing operation duration was found after aortoiliac surgery (OR 2.08), bladder surgery (OR 1.71) or prostate surgery (odds ratio 1.22).

Conclusion

Performing TEP inguinal hernia repair after lower abdominal surgery slightly increases the operation duration, however there is no negative effect on the length of stay and the complication- or conversion rate. Therefore, we consider TEP to be a feasible and safe operation technique also for patients who previously underwent open lower abdominal surgery.
Does the non-absorbable suture closure of the jejunal mesenteric defect reduce the incidence and severity of internal hernias after laparoscopic Roux-en-Y gastric bypass?
Authors: Schneider R , Schulenburg M , Kraljević M , Klasen J M , Peters T , Wölnerhanssen B , Peterli R
Published: May 2021

Objective

Internal hernias (IH) are frequent complications after laparoscopic Roux-en-Y gastric bypass (LRYGB). Closure of the jejunal mesenteric and the Petersen defect reduces IH incidence in prospective and retrospective trials. This study investigates whether closing the jejunal mesenteric space alone by non-absorbable suture and splitting the omentum can be beneficial to prevent IH after LRYGB.

Methods

Observational cohort study of 785 patients undergoing linear LRYGB including omental split at a single institution, 493 without jejunal mesenteric defect closure, 292 with closure by non-absorbable suture with a minimal follow-up of 2 years. Patients were assessed for appearance and severity of IH. Additionally, open mesenteric gaps without herniated bowel, as well as early obstructions due to kinking of the entero-enterostomy (EE) were explored.

Results

By primary mesenteric defect closure, the rate of manifest jejunal mesenteric and Petersen IH could be reduced from 6.5% to 3.8%, but without reaching statistical significance. The most common location for an IH was the jejunal mesenteric space, where defect closure during primary surgery could reduce the rate of IH from 5.3% to 2.4%. Higher weight loss seemed to increase the risk of developing an IH.

Conclusion

The closure of the jejunal mesenteric defect by non-absorbable suture can reduce the rate of IH at the jejunal mesenteric space after LRYGB. However, the beneficial effect in our collective is smaller than expected, especially in patients with excellent weight loss. Petersen IH rate remained low by consequent T-shape split of the omentum without suturing of the defect.
Roux-en-Y gastric bypass with a long compared to a short biliopancreatic limb leads to better weight loss and glycemic control in obese mice
Authors: Schneider R , Kraljević M , Peterson C J , Lazaridis I , Rohm T V , Bosch A J T , Low A J Y , Vonaesch P , Peterli R , Delko T , Cavelti-Weder C
Published: May 2021

Objective

Roux-en-Y gastric bypass (RYGB) shows durable long-term weight loss and control of comorbidities in randomized controlled trials. However, the impact of the proportions of the biliopancreatic limb (BPL) and the total alimentary limb (TALL) on weight loss or glucose metabolism is still unclear.

Methods

Six weeks old C57BL/6J mice were fed high fat diet (HFD) to induce obesity and glucose intolerance. Mice underwent RYGB surgery with a very-long BPL (35% of total bowel length [TBL]), long BPL (25% of TBL), short BPL (15 % of TBL), or sham surgery. The alimentary limb (AL) was adjusted in dependency on the BPL to achieve a fixed CC length. Glycemia was assessment by intraperitoneal glucose tolerance tests.

Results

Mice undergoing RYGB with a very-long BPL showed excessive weight loss and mortality and were therefore excluded for further analyses. Total weight loss (TWL%) was significantly higher in the long BPL- compared to short BPL-group. Mice with a long BPL showed significantly improved glucose tolerance 14 days postoperatively, while 35 days postoperatively, the improvement in glucose tolerance with a long BPL was much less distinctive.

Conclusion

RYGB with a longer BPL leads to improved results including weight loss and glucose tolerance. However, the metabolic improvements seem to decrease over time. These findings could potentially be translated to humans by adjusting the BPL according to body weight and comorbidities. To avoid possible negative effects of a longer BPL total bowel length measurement is mandatory.
Comparison of injury patterns between electric bicycle, bicycle and motorcycle accidents
Authors: Spörri E , Pape H -C , Rauer T
Published: May 2021

Objective

Electric bicycles (E-bikes) are an increasingly popular means of transport, especially in the current Covid-19 pandemic situation. Accident statistics show that E-bikes are growingly involved in traffic accidents. This study evaluates the injury pattern and severity of E-bike injuries in direct comparison to injuries in motorcycle and bicycle accidents.

Methods

In a retrospective cohort study, the data of 1796 patients who were treated at a Level I Trauma Center between 2009 and 2018 due to traffic accident, involving bicycles, E-bikes or motorcycles, were evaluated and compared with regard to injury patterns and injury severity. Accident victims treated as inpatients with at least 16 years of age were included in this study. Pillion passengers and outpatients were excluded.

Results

The following distribution was found in the individual groups: 67 E-bike, 1141 bicycle and 588 motorcycle accidents. The injury pattern of E-bikers resembled that of bicyclists much more than that of motorcyclists. The patients with E-bike accidents were almost 14 years older and had a higher incidence of moderate traumatic brain injuries than patients with bicycle accidents. Considering the E-bike riders wore nearly twice as often a helmet as bicycle riders. In comparison, the motorcyclists involved in an accident had fewer facial injuries, but more frequent and more serious injuries to the spine, abdomen and lower extremities.

Conclusion

The overall E-bike injury pattern is similar to that of cyclists. The differences in the injury pattern to motorcycle accidents could be due to the higher speeds at the time of the accident, the different protection and vehicle architecture. What is striking, however, is the higher age and the increased craniocerebral trauma of the E-bikers involved in accidents compared to the cyclists. Older and untrained people who have a slower reaction time and less control over the E-bike could benefit from head protection or practical courses similar to motorcyclists.
Increased incidence of complicated acute appendicitis after the first COVID-19 pandemic peak: Have patients a different attitude towards COVID-hospitals?
Authors: Passoni S , Giuliani M , Arigoni M
Published: May 2021

Objective

The 11 March 2020 the World Health Organisation considered the COVID-19 Infection a pandemic disease. Between March and May 2020, the region of southern Switzerland was affected by the first pandemic peak, which was managed by dividing hospitals in Covid and non Covid facilities and by reducing elective surgery. At the end of the pandemic peak hospitals returned to their original structure but there was concern as to possible avoidance of former COVID facilities by patients because of fear of contracting of COVID-19 infection. For acute situations such as acute appendicitis, this could imply a delay of treatment. The aim of this retrospective study is to analyse the increment in incidence of complicated appendicitis in the post-pandemic period at our institution.

Methods

Clinical data of patients who underwent appendectomies in the period before and after the COVID-19 pandemic were analysed and compared. Diagnosis was based histopathological examination and/or on intra-operative or CT findings. Complicated appendicitis was defined as the presence of perforated or gangrenous appendicitis on histopathology or the presence of an abscess on CT scan. The incidence of complicated appendicitis, the time between onset of symptoms and patient admission (TOSA), the initial inflammatory blood tests and the complication rate was compared between the two periods.

Results

79 patients were included in the study, 31 in the post-COVID-19 peak group (A), April - October 2020, and 48 in the pre-pandemic group (B), April - October 2019. Incidence of complicated appendicitis was significantly higher in group A (55% vs 14% p = 0.02). These findings correlate with a greater TOSA (mean time 35 hours vs 17 hours, p = 0.01) and higher inflammatory values in the initial blood test, (mean WBC count 14.8 G/l vs 12.9 G/l, p = 0.08 and mean CRP value 73 mg/l vs 43 mg/l, p = 0.01) in group A.

Conclusion

Our data show a clear increase of incidence of complicated acute appendicitis after the pandemic peak in our hospital. Indeed patients tended to wait longer to visit our emergency department after the pandemic peak. One explanation is a possible fear by the patients of contracting COVID-19 infection in a former COVID hospital. Management of surgical emergencies during and after a pandemic peak phase should take into account the fact that patients may wait longer to visit a doctor thus aggravating the degree of their disease.