Objective: By observing the treatment and nursing care of a patient with Grade IV capsular contracture following breast cancer expander implantation and subsequent Stage II reconstruction, we aim to analyze the reason...Objective: By observing the treatment and nursing care of a patient with Grade IV capsular contracture following breast cancer expander implantation and subsequent Stage II reconstruction, we aim to analyze the reasons for the formation of capsular contracture after Stage I expander implantation and prevent its recurrence following Stage II reconstruction. Methods: In May 2020, the patient noticed an increase in the size of a breast mass. In August, she underwent AC-THP neoadjuvant chemotherapy, followed by a “right breast-conserving nipple-areolar subglandular excision + right axillary lymph node dissection + expander implantation” surgery in November 2020. Radiation therapy began in January 2021. During radiation therapy, the patient experienced severe breast hardening, distortion, tenderness, and was diagnosed with Grade IV capsular contracture. To relieve the capsular contracture, the patient underwent a “contracted capsule incision and release procedure + removal of the right breast expander + right breast implantation” surgery in July 2021. Postoperatively, measures were taken to prevent incision infection, emphasizing aseptic techniques, ensuring smooth negative pressure drainage, reducing skin flap tension, monitoring skin flap blood supply, actively preventing subcutaneous effusion and hematoma, and applying appropriate compression dressings. Results: The patient was discharged after the removal of the drainage tube. During the postoperative follow-up at 3 and 6 months, there was no recurrence of capsular contracture, and the breast appeared full, upright, and relatively soft. There were no complications such as hematoma, infection, breast implant rupture, breast sagging, or displacement. The patient had a good outcome without additional financial or surgical burdens. Conclusion: The occurrence of Grade IV capsular contracture in the patient is generally related to infection after Stage I expander implantation, improper compression dressing, excessive saline injection causing content infiltration, and radiation therapy. Therefore, it is recommended to enhance the intraoperative and postoperative prophylactic use of antibiotics after Stage I expander implantation. Intermittent saline injection after surgery, with the amount of saline gradually increasing rather than filling all at once, is advisable. This helps the breast tissue gradually adapt to expansion, reducing the risk of capsular contracture. Postoperatively, patients should be instructed to wear pressure garments and breast elastic bandages while intensifying breast monitoring during radiation therapy and increasing postoperative follow-up.展开更多
To investigate the configuration consideration of expander in transcritical carbon dioxide two-stage compression cycle, the best place in the cycle should be searched for to reinvest the recovery work so as to improve...To investigate the configuration consideration of expander in transcritical carbon dioxide two-stage compression cycle, the best place in the cycle should be searched for to reinvest the recovery work so as to improve the system efficiency. The expander and the compressor are connected to the same shaft and integrated into one unit, with the latter being driven by the former, thus the transfer loss and leakage loss can be decreased greatly. In these systems, the expander can be either connected with the first stage compressor (shortened as DCDL cycle) or the second stage compressor (shortened as DCDH cycle), but the two configuration ways can get different performances. By setting up theoretical model for two kinds of expander configuration ways in the transcritical carbon dioxide two-stage compression cycle, the first and the second laws of thermodynamics are used to analyze the coefficient of performance, exergy efficiency, inter-stage pressure, discharge temperature and exergy losses of each component for the two cycles. From the model results, the performance of DCDH cycle is better than that of DCDL cycle. The analysis results are indispensable to providing a theoretical basis for practical design and operating.展开更多
Improvement of measurement precision and repeatability is one of the issues currently faced by the laser-induced breakdown spectroscopy (LIBS) technique, which is expected to be capable of precise and accurate quant...Improvement of measurement precision and repeatability is one of the issues currently faced by the laser-induced breakdown spectroscopy (LIBS) technique, which is expected to be capable of precise and accurate quantitative analysis. It was found that there was great potential to improve the signal quality and repeatability by reducing the laser beam divergence angle using a suitable beam expander (BE). In the present work, the influences of several experimental parameters for the case with BE are studied in order to optimize the analytical performances: the signal to noise ratio (SNR) and the relative standard deviation (RSD). We demonstrate that by selecting the optimal experimental parameters, the BE-included LIBS setup can give higher SNR and lower RSD values of the line intensity normalized by the whole spectrum area. For validation purposes, support vector machine (SVM) regression combined with principal component analysis (PCA) was used to establish a calibration model to realize the quantitative analysis of the ash content. Good agreement has been found between the laboratory measurement results from the LIBS method and those from the traditional method. The measurement accuracy presented here for ash content analysis is estimated to be 0.31%, while the average relative error is 2.36%.展开更多
BACKGROUND High-riding nipple is one of the common complications after mastopexty and breast reconstruction.However,to date,a limited number of techniques have concentrated on how to lower the high-riding nipple with ...BACKGROUND High-riding nipple is one of the common complications after mastopexty and breast reconstruction.However,to date,a limited number of techniques have concentrated on how to lower the high-riding nipple with enlarged areola.CASE SUMMARY This is a case report describing a combination of surgical techniques to decrease high-riding nipple.A 26-year-old woman,who previously underwent several breast operations,sought correction for high-riding nipple with enlarged areola.Expanders were used and multi-stage techniques were performed.After one year of follow-up,lowered nipple,reduced areola size,ensured nipple blood supply,and improved breast ptosis were achieved,and the patient was satisfied with the breast contour.CONCLUSION The proposed technique offers a feasible treatment option for postoperative nipple over-elevation combined with areola dilation.展开更多
To improve the coefficient of performance (COP) of CO2 transcritical reverse cycle and determine the most efficient cycle, comparison analysis on (single-and) two-stage CO2 transcritical cycles with internal heat ...To improve the coefficient of performance (COP) of CO2 transcritical reverse cycle and determine the most efficient cycle, comparison analysis on (single-and) two-stage CO2 transcritical cycles with internal heat exchanger (IHX) or expander is presented adopting the principle of thermodynamics. Results indicate that the COP of four cycles,namely single-stage compression with IHX (SI), single-stage compression with expander (SE), two-stage compression with IHX (TI) and two-stage compression with expander (TE), can be ranged as TE>SE>TI>SI. It presents that adopting an expander to recover expansion power is the primary method to improve the COP of CO2 transcritical reverse cycle if the efficiency of the expander is up to a certain value. Under supposed operating condition, where the outlet temperature of gas cooler is 35 ℃ and the evaporating temperature is 5 ℃, the COP of TE cycle is about 4200 higher than that of SI cycle when the expander efficiency is 0.6 and the degree of superheat of IHX is 15 ℃. Therefore TE cycle is the most recommendatory one and it is better to adopt TE in those high-cooling capacity systems because its technology cost will be higher.展开更多
Background:Plasma expanders are widely used for acute normovolemic hemodilution(ANH).However,existing studies have not focused on large-volume infusion with colloidal plasma expanders,and there is a lack of studies th...Background:Plasma expanders are widely used for acute normovolemic hemodilution(ANH).However,existing studies have not focused on large-volume infusion with colloidal plasma expanders,and there is a lack of studies that compare the effects of different plasma expanders.Methods:The viscosity,hydrodynamic radius(Rh)and colloid osmotic pressure(COP)of plasma expanders were determined by a cone-plate viscometer,Zetasizer and cut-off membrane,respectively.Sixty male rats were randomized into five groups with Gelofusine(Gel),Hydroxyethyl Starch 200/0.5(HES200),Hydroxyethyl Starch 130/0.4(HES130),Hydroxyethyl Starch 40(HES40),and Dextran 40(Dex40),with 12 rats used in each group to build the ANH model.ANH was performed by the withdrawal of blood and simultaneous infusion of plasma expanders.Acid-base,lactate,blood gas and physiological parameters were detected.Results:Gel had a lower intrinsic viscosity than HES200 and HES130(P<0.01),but at a low shear rate in a mixture of colloids,red cells and plasma,Gel had a higher viscosity(P<0.05 or P<0.01,respectively).For hydroxyethyl starch plasma expanders,the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of Rh from 10.7 nm to 20.2 nm.A severe ANH model,with the hematocrit of 40%of the baseline level,was established and accompanied by disturbances in acid-base,lactate and blood gas parameters.At the end of ANH and 60 min afterward,the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other groups.The systolic blood pressure(SBP),diastolic blood pressure(DBP),and mean arterial pressure(MAP)decreased significantly in all groups at the end of ANH.The DBP and MAP in the Dex40 group further decreased 60 min after the end of ANH.During the process of ANH,the Dex40 group showed a drop and recovery in SBP,DBP and MAP.The DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points(P<0.05 or P<0.01).Conclusions:Gel had a low intrinsic viscosity but may increase the whole blood viscosity at low shear rates.Rh and COP showed a strong correlation among hydroxyethyl starch plasma expanders.Dex40 showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other plasma expanders.During the process of ANH,Dex40 displayed a V-shaped recovery pattern for blood pressure,and HES200 had the advantage in sustaining the DBP and MAP at some time points.展开更多
Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.Howe...Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.展开更多
In this note,we prove that expanders cannot be coarsely embedded into group extensions of sequences of groups which are coarsely embeddable into Hardamad manifolds and certain Banach spaces due to the similar concentr...In this note,we prove that expanders cannot be coarsely embedded into group extensions of sequences of groups which are coarsely embeddable into Hardamad manifolds and certain Banach spaces due to the similar concentration theorems.展开更多
In this paper, a class of metric spaces which include Hilbert spaces and Hadamard manifolds are defined. And the expanders cannot be coarsely embedded into this class of metric spaces are proved.
This paper is concerned with the investigation, experiment and design analyses on the application of active magnetic bearings for a 150M 3 turbo oxygen gas expander having 1.16 kg weight and 30 mm diameter rotor, whi...This paper is concerned with the investigation, experiment and design analyses on the application of active magnetic bearings for a 150M 3 turbo oxygen gas expander having 1.16 kg weight and 30 mm diameter rotor, which was supported by two aerostatic bearings formerly. Now, the machine can work steady at a rotation speed of 92,000 r/min, and can be run up to a maximum rotation speed of 104,000 r/min.展开更多
To make the large-scale helium cryogenic system of fusion device EAST (experimen- tal advanced super-conducting tokamak) run stably, as the core part, the helium turbine expander must meet the requirement of refrige...To make the large-scale helium cryogenic system of fusion device EAST (experimen- tal advanced super-conducting tokamak) run stably, as the core part, the helium turbine expander must meet the requirement of refrigeration capacity. However, previous designs were based on one dimension flow to determine the average fluid parameters and geometric parameters of impeller cross-sections, so that it could not describe real physical processes in the internal flow of the tur- bine expander. Therefore, based on the inverse proposition of streamline curvature method in the context of quasi-three-dimensional flows, the all-over-controlled vortex concept was adopted to design the impeller under specified condition. The wrap angle of the impeller blade and the whole flow distribution on the meridian plane were obtained; meanwhile the performance of the designed impeller was analyzed. Thus a new design method is proposed here for the inverse proposition of the helium turbine expander impeller.展开更多
This article is dealing with a development of custom chip expander platform with the possibility of accurate temperature control and integration of additional silicon-based features. Such platform may serve as a usefu...This article is dealing with a development of custom chip expander platform with the possibility of accurate temperature control and integration of additional silicon-based features. Such platform may serve as a useful tool which facilitates the burdens connected with measurement and analysis tasks of experimental semiconductor structures. The devised solution provides the functionality of carrier substrate (Al2O3 compound) with CTE compatibility to the experimental silicon chip and is fully customizable with respect to a particular chip. It also allows achieving an easy fan-out of small-diameter chip terminals into a larger, more convenient area and placement of chip specimens conveniently into space-constrained chamber of the AFM microscopes, probe stations, etc. Real application of the developed chip expander platform is demonstrated in context of digital reconfigurable circuits based on polymorphic electronics. In this case the chip expander with attached polymorphic chip REPOMO is thermally stabilized at an ambient temperature level up to approximately 135。C and its sensitivity to this phenomenon is demonstrated.展开更多
True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods ar...True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods are expected to have some shortcomings;the Unilateral dental expander appliance used to restore unilateral cross bite dental arch is an uncommon appliance;for this,a designed new device is needed.This paper aimed to invite a new unilateral dental expander appliance(UDEX)to treat unilateral dental posterior crossbite in adults using available dental material,easy to use and handle,well tolerated by the patient,and biocompatible with oral structure.It could find that in all dental markets and dental clinics—an eighteen-year-old female with bilateral crossbite and upper and lower dental arch crowding.During active orthodontic treatment,a quad-helix expander had broken from one side at soldering between band and wire attachment.The patient did not show up to the clinic for a while due to COVID 19 pandemic lockdown,leading to a true unilateral crossbite at the dental arch’s upper left side,especially at the molar premolars area.This unilateral cross bite was treated using a new specially designed expanded appliance as a unilateral posterior cross bite dental maxillary expander.As a result of this study,orthodontic treatment was finished within(15)months,much less than expected.We obtained Class I molar and canine relationships with uncrossed dental arches in both upper arch sides,proper overbite and overjet with well-leveled and aligned teeth as it confirmed by clinical examination and radiographic images(OPG Orthopantomogram)and cephalometric radiograph(WebCeph analysis digitalized computer program).Conclude from that,the newly designed unilateral dental expander(UDEX)is proven to be useful for treating real unilateral posterior crossbites as single molar or premolar tooth and multiple joint unilateral crossed posterior teeth.Also,it could easily modify it for future unilateral crossed purposes.This appliance was fabricated using readily available dental material,well tolerated by patients,and reduced the need for excessive patient compliance.An orthodontist could fabricate devices,or cautious laboratory work is required;it can rapidly achieve favorable results.展开更多
Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,t...Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.展开更多
BACKGROUND Bone transport and distraction osteogenesis has been widely used to treat bone defects after traumatic surgery,but,skin and soft tissue incarceration can be as high as 27.6%.AIM To investigate the efficacy ...BACKGROUND Bone transport and distraction osteogenesis has been widely used to treat bone defects after traumatic surgery,but,skin and soft tissue incarceration can be as high as 27.6%.AIM To investigate the efficacy of inserting a tissue expander to prevent soft tissue incarceration.METHODS Between January 2016 and December 2018,12 patients underwent implantation of a tissue expander in the subcutaneous layer in the vicinity of a tibial defect to maintain the soft tissue in position.A certain amount of normal saline was injected into the tissue expander during surgery and was then gradually extracted to shrink the expander during the course of transport distraction osteogenesis.The tissue expander was removed when the two ends of the tibial defect were close enough.RESULTS In all 12 patients,the expanders remained intact in the subcutaneous layer of the bone defect area during the course of transport distraction osteogenesis.When bone transport was adequate,the expander was removed and the bone transport process was completed.During the whole process,there was no incarceration of skin and soft tissue in the bone defect area.Complications occurred in one patient,who experienced poor wound healing.CONCLUSION The pre-filled expander technique can effectively avoid soft tissue incarceration.The authors’primary success with this method indicates that it may be a valuable tool in the management of incarcerated soft tissue.展开更多
To study the complex internal flow field variation and output characteristics of a variable base radius scroll expander,this paper uses dynamic mesh techniques and computational fluid dynamics(CFD)methods to perform t...To study the complex internal flow field variation and output characteristics of a variable base radius scroll expander,this paper uses dynamic mesh techniques and computational fluid dynamics(CFD)methods to perform transient numerical simulations of a variable base radius scroll expander.Analysis of the flow field in the working cavity of a variable base radius scroll expander at different spindle angles and the effect of different profiles,speeds and pressures on the output characteristics of the scroll expander.The results of the study show that due to the periodic blocking of the inlet by the orbiting scroll,the fluid hits the internal walls of the expander at different flow rates,with excessive mechanical losses,resulting in an uneven distribution of the internal flow field.At the same temperature,pressure and scroll plate diameter,the variable base radius scroll expander increases the output torque by 0.046 N·m,the output power by 9.634 W and the isentropic efficiency by 3.8%compared to the fixed base circle scroll expander.As the speed is inversely proportional to the output torque,the isentropic efficiency of the expander tends to increase and then decrease as the speed increases.The density of the fluid is directly proportional to the pressure over a range of pressures.As the pressure increases from 0.6 to 0.9 Mpa,the average mass flow rate and isentropic efficiency increase by 0.02357 kg/s,and 6.61%,respectively.展开更多
Introduction: As new vaccines become available, countries must assess the relevance to introduce them into their vaccination schedules. Malawi has recently introduced several new vaccines and plans to introduce more. ...Introduction: As new vaccines become available, countries must assess the relevance to introduce them into their vaccination schedules. Malawi has recently introduced several new vaccines and plans to introduce more. This study was conducted to identify key factors that need to be considered when deciding to introduce a new vaccine and current challenges faced by low and middle income countries using Malawi as an example. Methodology: The study employed a desk review approach, examining published literature from various sources such as PubMed, Medline, and Google Scholar. Policy documents from organizations like the World Health Organization, GAVI the Alliance, and the Ministry of Health for Malawi were also included. A total of 99 articles and documents on new vaccine introduction, challenges of immunization, policy documents in immunization and health systems strengthening were included. The review focused on addressing five key areas critical to new vaccine introduction namely: the need for a vaccine, availability of the vaccine, safety and effectiveness of the vaccine, demand for the vaccine, and the prudent use of public or private funds. Results: Malawi considered the burden of cervical cancer and the significance of malaria in the country when introducing the HPV and malaria vaccines. The country opted for vaccines that can be handled by the cold chain capacity and available human resources. Despite that malaria vaccine and Typhoid Conjugate Vaccine trials were done in country, there are limited vaccine safety and efficacy trials conducted in Malawi, leading to a reliance on WHO-prequalified vaccines. Demand for newly introduced vaccines varied, with high demand for Oral Cholera Vaccine during a cholera outbreak, while demand for COVID-19 vaccines decreased over time. Although cost-effectiveness studies were limited in the country, 2 studies indicated that Typhoid Conjugate Vaccine and malaria vaccine would be cost effective. All these have been implemented despite having challenges like lack of accurate surveillance data, inadequate cold chain capacity, limited safety and efficacy vaccine clinical trials, political influence, and limited funding. Conclusion: Despite several challenges Malawi set a good example of the careful considerations required before introducing a new vaccine. The process involves data review, priority setting, precise planning, and consultation with stakeholders. Low-income countries should invest in vaccine safety, efficacy, and cost-effectiveness trials.展开更多
Existing mobile robots mostly use graph search algorithms for path planning,which suffer from relatively low planning efficiency owing to high redundancy and large computational complexity.Due to the limitations of th...Existing mobile robots mostly use graph search algorithms for path planning,which suffer from relatively low planning efficiency owing to high redundancy and large computational complexity.Due to the limitations of the neighborhood search strategy,the robots could hardly obtain the most optimal global path.A global path planning algorithm,denoted as EDG*,is proposed by expanding nodes using a well-designed expanding disconnected graph operator(EDG)in this paper.Firstly,all obstacles are marked and their corners are located through the map pre-processing.Then,the EDG operator is designed to find points in non-obstruction areas to complete the rapid expansion of disconnected nodes.Finally,the EDG*heuristic iterative algorithm is proposed.It selects the candidate node through a specific valuation function and realizes the node expansion while avoiding collision with a minimum offset.Path planning experiments were conducted in a typical indoor environment and on the public dataset CSM.The result shows that the proposed EDG*reduced the planning time by more than 90%and total length of paths reduced by more than 4.6%.Compared to A*,Dijkstra and JPS,EDG*does not show an exponential explosion effect in map size.The EDG*showed better performance in terms of path smoothness,and collision avoidance.This shows that the EDG*algorithm proposed in this paper can improve the efficiency of path planning and enhance path quality.展开更多
文摘Objective: By observing the treatment and nursing care of a patient with Grade IV capsular contracture following breast cancer expander implantation and subsequent Stage II reconstruction, we aim to analyze the reasons for the formation of capsular contracture after Stage I expander implantation and prevent its recurrence following Stage II reconstruction. Methods: In May 2020, the patient noticed an increase in the size of a breast mass. In August, she underwent AC-THP neoadjuvant chemotherapy, followed by a “right breast-conserving nipple-areolar subglandular excision + right axillary lymph node dissection + expander implantation” surgery in November 2020. Radiation therapy began in January 2021. During radiation therapy, the patient experienced severe breast hardening, distortion, tenderness, and was diagnosed with Grade IV capsular contracture. To relieve the capsular contracture, the patient underwent a “contracted capsule incision and release procedure + removal of the right breast expander + right breast implantation” surgery in July 2021. Postoperatively, measures were taken to prevent incision infection, emphasizing aseptic techniques, ensuring smooth negative pressure drainage, reducing skin flap tension, monitoring skin flap blood supply, actively preventing subcutaneous effusion and hematoma, and applying appropriate compression dressings. Results: The patient was discharged after the removal of the drainage tube. During the postoperative follow-up at 3 and 6 months, there was no recurrence of capsular contracture, and the breast appeared full, upright, and relatively soft. There were no complications such as hematoma, infection, breast implant rupture, breast sagging, or displacement. The patient had a good outcome without additional financial or surgical burdens. Conclusion: The occurrence of Grade IV capsular contracture in the patient is generally related to infection after Stage I expander implantation, improper compression dressing, excessive saline injection causing content infiltration, and radiation therapy. Therefore, it is recommended to enhance the intraoperative and postoperative prophylactic use of antibiotics after Stage I expander implantation. Intermittent saline injection after surgery, with the amount of saline gradually increasing rather than filling all at once, is advisable. This helps the breast tissue gradually adapt to expansion, reducing the risk of capsular contracture. Postoperatively, patients should be instructed to wear pressure garments and breast elastic bandages while intensifying breast monitoring during radiation therapy and increasing postoperative follow-up.
文摘To investigate the configuration consideration of expander in transcritical carbon dioxide two-stage compression cycle, the best place in the cycle should be searched for to reinvest the recovery work so as to improve the system efficiency. The expander and the compressor are connected to the same shaft and integrated into one unit, with the latter being driven by the former, thus the transfer loss and leakage loss can be decreased greatly. In these systems, the expander can be either connected with the first stage compressor (shortened as DCDL cycle) or the second stage compressor (shortened as DCDH cycle), but the two configuration ways can get different performances. By setting up theoretical model for two kinds of expander configuration ways in the transcritical carbon dioxide two-stage compression cycle, the first and the second laws of thermodynamics are used to analyze the coefficient of performance, exergy efficiency, inter-stage pressure, discharge temperature and exergy losses of each component for the two cycles. From the model results, the performance of DCDH cycle is better than that of DCDL cycle. The analysis results are indispensable to providing a theoretical basis for practical design and operating.
基金supported by the 973 Program of China(No.2012CB921603)National Natural Science Foundation of China(Nos.61475093,61127017,61178009,61108030,61378047,61275213,61475093,and 61205216)+3 种基金the National Key Technology R&D Program of China(No.2013BAC14B01)the Shanxi Natural Science Foundation(Nos.2013021004-1 and 2012021022-1)the Shanxi Scholarship Council of China(Nos.2013-011 and 2013-01)the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,China
文摘Improvement of measurement precision and repeatability is one of the issues currently faced by the laser-induced breakdown spectroscopy (LIBS) technique, which is expected to be capable of precise and accurate quantitative analysis. It was found that there was great potential to improve the signal quality and repeatability by reducing the laser beam divergence angle using a suitable beam expander (BE). In the present work, the influences of several experimental parameters for the case with BE are studied in order to optimize the analytical performances: the signal to noise ratio (SNR) and the relative standard deviation (RSD). We demonstrate that by selecting the optimal experimental parameters, the BE-included LIBS setup can give higher SNR and lower RSD values of the line intensity normalized by the whole spectrum area. For validation purposes, support vector machine (SVM) regression combined with principal component analysis (PCA) was used to establish a calibration model to realize the quantitative analysis of the ash content. Good agreement has been found between the laboratory measurement results from the LIBS method and those from the traditional method. The measurement accuracy presented here for ash content analysis is estimated to be 0.31%, while the average relative error is 2.36%.
文摘BACKGROUND High-riding nipple is one of the common complications after mastopexty and breast reconstruction.However,to date,a limited number of techniques have concentrated on how to lower the high-riding nipple with enlarged areola.CASE SUMMARY This is a case report describing a combination of surgical techniques to decrease high-riding nipple.A 26-year-old woman,who previously underwent several breast operations,sought correction for high-riding nipple with enlarged areola.Expanders were used and multi-stage techniques were performed.After one year of follow-up,lowered nipple,reduced areola size,ensured nipple blood supply,and improved breast ptosis were achieved,and the patient was satisfied with the breast contour.CONCLUSION The proposed technique offers a feasible treatment option for postoperative nipple over-elevation combined with areola dilation.
文摘To improve the coefficient of performance (COP) of CO2 transcritical reverse cycle and determine the most efficient cycle, comparison analysis on (single-and) two-stage CO2 transcritical cycles with internal heat exchanger (IHX) or expander is presented adopting the principle of thermodynamics. Results indicate that the COP of four cycles,namely single-stage compression with IHX (SI), single-stage compression with expander (SE), two-stage compression with IHX (TI) and two-stage compression with expander (TE), can be ranged as TE>SE>TI>SI. It presents that adopting an expander to recover expansion power is the primary method to improve the COP of CO2 transcritical reverse cycle if the efficiency of the expander is up to a certain value. Under supposed operating condition, where the outlet temperature of gas cooler is 35 ℃ and the evaporating temperature is 5 ℃, the COP of TE cycle is about 4200 higher than that of SI cycle when the expander efficiency is 0.6 and the degree of superheat of IHX is 15 ℃. Therefore TE cycle is the most recommendatory one and it is better to adopt TE in those high-cooling capacity systems because its technology cost will be higher.
基金supported by the National Key Research and Development Program of China(2018YFC1106503)。
文摘Background:Plasma expanders are widely used for acute normovolemic hemodilution(ANH).However,existing studies have not focused on large-volume infusion with colloidal plasma expanders,and there is a lack of studies that compare the effects of different plasma expanders.Methods:The viscosity,hydrodynamic radius(Rh)and colloid osmotic pressure(COP)of plasma expanders were determined by a cone-plate viscometer,Zetasizer and cut-off membrane,respectively.Sixty male rats were randomized into five groups with Gelofusine(Gel),Hydroxyethyl Starch 200/0.5(HES200),Hydroxyethyl Starch 130/0.4(HES130),Hydroxyethyl Starch 40(HES40),and Dextran 40(Dex40),with 12 rats used in each group to build the ANH model.ANH was performed by the withdrawal of blood and simultaneous infusion of plasma expanders.Acid-base,lactate,blood gas and physiological parameters were detected.Results:Gel had a lower intrinsic viscosity than HES200 and HES130(P<0.01),but at a low shear rate in a mixture of colloids,red cells and plasma,Gel had a higher viscosity(P<0.05 or P<0.01,respectively).For hydroxyethyl starch plasma expanders,the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of Rh from 10.7 nm to 20.2 nm.A severe ANH model,with the hematocrit of 40%of the baseline level,was established and accompanied by disturbances in acid-base,lactate and blood gas parameters.At the end of ANH and 60 min afterward,the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other groups.The systolic blood pressure(SBP),diastolic blood pressure(DBP),and mean arterial pressure(MAP)decreased significantly in all groups at the end of ANH.The DBP and MAP in the Dex40 group further decreased 60 min after the end of ANH.During the process of ANH,the Dex40 group showed a drop and recovery in SBP,DBP and MAP.The DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points(P<0.05 or P<0.01).Conclusions:Gel had a low intrinsic viscosity but may increase the whole blood viscosity at low shear rates.Rh and COP showed a strong correlation among hydroxyethyl starch plasma expanders.Dex40 showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other plasma expanders.During the process of ANH,Dex40 displayed a V-shaped recovery pattern for blood pressure,and HES200 had the advantage in sustaining the DBP and MAP at some time points.
基金supported by the following funds:National Natural Science Foundation of China(51935014,52165043)Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects(20225BCJ23008)+1 种基金Jiangxi Provincial Natural Science Foundation(20224ACB204013,20224ACB214008)Scientific Research Project of Anhui Universities(KJ2021A1106)。
文摘Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.
文摘In this note,we prove that expanders cannot be coarsely embedded into group extensions of sequences of groups which are coarsely embeddable into Hardamad manifolds and certain Banach spaces due to the similar concentration theorems.
文摘In this paper, a class of metric spaces which include Hilbert spaces and Hadamard manifolds are defined. And the expanders cannot be coarsely embedded into this class of metric spaces are proved.
文摘This paper is concerned with the investigation, experiment and design analyses on the application of active magnetic bearings for a 150M 3 turbo oxygen gas expander having 1.16 kg weight and 30 mm diameter rotor, which was supported by two aerostatic bearings formerly. Now, the machine can work steady at a rotation speed of 92,000 r/min, and can be run up to a maximum rotation speed of 104,000 r/min.
文摘To make the large-scale helium cryogenic system of fusion device EAST (experimen- tal advanced super-conducting tokamak) run stably, as the core part, the helium turbine expander must meet the requirement of refrigeration capacity. However, previous designs were based on one dimension flow to determine the average fluid parameters and geometric parameters of impeller cross-sections, so that it could not describe real physical processes in the internal flow of the tur- bine expander. Therefore, based on the inverse proposition of streamline curvature method in the context of quasi-three-dimensional flows, the all-over-controlled vortex concept was adopted to design the impeller under specified condition. The wrap angle of the impeller blade and the whole flow distribution on the meridian plane were obtained; meanwhile the performance of the designed impeller was analyzed. Thus a new design method is proposed here for the inverse proposition of the helium turbine expander impeller.
文摘This article is dealing with a development of custom chip expander platform with the possibility of accurate temperature control and integration of additional silicon-based features. Such platform may serve as a useful tool which facilitates the burdens connected with measurement and analysis tasks of experimental semiconductor structures. The devised solution provides the functionality of carrier substrate (Al2O3 compound) with CTE compatibility to the experimental silicon chip and is fully customizable with respect to a particular chip. It also allows achieving an easy fan-out of small-diameter chip terminals into a larger, more convenient area and placement of chip specimens conveniently into space-constrained chamber of the AFM microscopes, probe stations, etc. Real application of the developed chip expander platform is demonstrated in context of digital reconfigurable circuits based on polymorphic electronics. In this case the chip expander with attached polymorphic chip REPOMO is thermally stabilized at an ambient temperature level up to approximately 135。C and its sensitivity to this phenomenon is demonstrated.
文摘True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods are expected to have some shortcomings;the Unilateral dental expander appliance used to restore unilateral cross bite dental arch is an uncommon appliance;for this,a designed new device is needed.This paper aimed to invite a new unilateral dental expander appliance(UDEX)to treat unilateral dental posterior crossbite in adults using available dental material,easy to use and handle,well tolerated by the patient,and biocompatible with oral structure.It could find that in all dental markets and dental clinics—an eighteen-year-old female with bilateral crossbite and upper and lower dental arch crowding.During active orthodontic treatment,a quad-helix expander had broken from one side at soldering between band and wire attachment.The patient did not show up to the clinic for a while due to COVID 19 pandemic lockdown,leading to a true unilateral crossbite at the dental arch’s upper left side,especially at the molar premolars area.This unilateral cross bite was treated using a new specially designed expanded appliance as a unilateral posterior cross bite dental maxillary expander.As a result of this study,orthodontic treatment was finished within(15)months,much less than expected.We obtained Class I molar and canine relationships with uncrossed dental arches in both upper arch sides,proper overbite and overjet with well-leveled and aligned teeth as it confirmed by clinical examination and radiographic images(OPG Orthopantomogram)and cephalometric radiograph(WebCeph analysis digitalized computer program).Conclude from that,the newly designed unilateral dental expander(UDEX)is proven to be useful for treating real unilateral posterior crossbites as single molar or premolar tooth and multiple joint unilateral crossed posterior teeth.Also,it could easily modify it for future unilateral crossed purposes.This appliance was fabricated using readily available dental material,well tolerated by patients,and reduced the need for excessive patient compliance.An orthodontist could fabricate devices,or cautious laboratory work is required;it can rapidly achieve favorable results.
基金funding support from National Natural Science Foundation of China(Grant No.52179109)Jiangsu Provincial Natural Science Foundation(Grant No.BK20230967)Open Research Fund of State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(Grant No.KF2022-02).
文摘Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.
文摘BACKGROUND Bone transport and distraction osteogenesis has been widely used to treat bone defects after traumatic surgery,but,skin and soft tissue incarceration can be as high as 27.6%.AIM To investigate the efficacy of inserting a tissue expander to prevent soft tissue incarceration.METHODS Between January 2016 and December 2018,12 patients underwent implantation of a tissue expander in the subcutaneous layer in the vicinity of a tibial defect to maintain the soft tissue in position.A certain amount of normal saline was injected into the tissue expander during surgery and was then gradually extracted to shrink the expander during the course of transport distraction osteogenesis.The tissue expander was removed when the two ends of the tibial defect were close enough.RESULTS In all 12 patients,the expanders remained intact in the subcutaneous layer of the bone defect area during the course of transport distraction osteogenesis.When bone transport was adequate,the expander was removed and the bone transport process was completed.During the whole process,there was no incarceration of skin and soft tissue in the bone defect area.Complications occurred in one patient,who experienced poor wound healing.CONCLUSION The pre-filled expander technique can effectively avoid soft tissue incarceration.The authors’primary success with this method indicates that it may be a valuable tool in the management of incarcerated soft tissue.
基金funded by the Provincial Natural Science Foundation of Shandong,Grant Number ZR2021ME233,ZR202103040075funded by the Qingdao Emerging Industry Cultivation Program,Grant Number 22-3-4-xxgg-7-gx.
文摘To study the complex internal flow field variation and output characteristics of a variable base radius scroll expander,this paper uses dynamic mesh techniques and computational fluid dynamics(CFD)methods to perform transient numerical simulations of a variable base radius scroll expander.Analysis of the flow field in the working cavity of a variable base radius scroll expander at different spindle angles and the effect of different profiles,speeds and pressures on the output characteristics of the scroll expander.The results of the study show that due to the periodic blocking of the inlet by the orbiting scroll,the fluid hits the internal walls of the expander at different flow rates,with excessive mechanical losses,resulting in an uneven distribution of the internal flow field.At the same temperature,pressure and scroll plate diameter,the variable base radius scroll expander increases the output torque by 0.046 N·m,the output power by 9.634 W and the isentropic efficiency by 3.8%compared to the fixed base circle scroll expander.As the speed is inversely proportional to the output torque,the isentropic efficiency of the expander tends to increase and then decrease as the speed increases.The density of the fluid is directly proportional to the pressure over a range of pressures.As the pressure increases from 0.6 to 0.9 Mpa,the average mass flow rate and isentropic efficiency increase by 0.02357 kg/s,and 6.61%,respectively.
文摘Introduction: As new vaccines become available, countries must assess the relevance to introduce them into their vaccination schedules. Malawi has recently introduced several new vaccines and plans to introduce more. This study was conducted to identify key factors that need to be considered when deciding to introduce a new vaccine and current challenges faced by low and middle income countries using Malawi as an example. Methodology: The study employed a desk review approach, examining published literature from various sources such as PubMed, Medline, and Google Scholar. Policy documents from organizations like the World Health Organization, GAVI the Alliance, and the Ministry of Health for Malawi were also included. A total of 99 articles and documents on new vaccine introduction, challenges of immunization, policy documents in immunization and health systems strengthening were included. The review focused on addressing five key areas critical to new vaccine introduction namely: the need for a vaccine, availability of the vaccine, safety and effectiveness of the vaccine, demand for the vaccine, and the prudent use of public or private funds. Results: Malawi considered the burden of cervical cancer and the significance of malaria in the country when introducing the HPV and malaria vaccines. The country opted for vaccines that can be handled by the cold chain capacity and available human resources. Despite that malaria vaccine and Typhoid Conjugate Vaccine trials were done in country, there are limited vaccine safety and efficacy trials conducted in Malawi, leading to a reliance on WHO-prequalified vaccines. Demand for newly introduced vaccines varied, with high demand for Oral Cholera Vaccine during a cholera outbreak, while demand for COVID-19 vaccines decreased over time. Although cost-effectiveness studies were limited in the country, 2 studies indicated that Typhoid Conjugate Vaccine and malaria vaccine would be cost effective. All these have been implemented despite having challenges like lack of accurate surveillance data, inadequate cold chain capacity, limited safety and efficacy vaccine clinical trials, political influence, and limited funding. Conclusion: Despite several challenges Malawi set a good example of the careful considerations required before introducing a new vaccine. The process involves data review, priority setting, precise planning, and consultation with stakeholders. Low-income countries should invest in vaccine safety, efficacy, and cost-effectiveness trials.
基金Supported by National Key Research and Development Program of China(Grant No.2022YFB4700402).
文摘Existing mobile robots mostly use graph search algorithms for path planning,which suffer from relatively low planning efficiency owing to high redundancy and large computational complexity.Due to the limitations of the neighborhood search strategy,the robots could hardly obtain the most optimal global path.A global path planning algorithm,denoted as EDG*,is proposed by expanding nodes using a well-designed expanding disconnected graph operator(EDG)in this paper.Firstly,all obstacles are marked and their corners are located through the map pre-processing.Then,the EDG operator is designed to find points in non-obstruction areas to complete the rapid expansion of disconnected nodes.Finally,the EDG*heuristic iterative algorithm is proposed.It selects the candidate node through a specific valuation function and realizes the node expansion while avoiding collision with a minimum offset.Path planning experiments were conducted in a typical indoor environment and on the public dataset CSM.The result shows that the proposed EDG*reduced the planning time by more than 90%and total length of paths reduced by more than 4.6%.Compared to A*,Dijkstra and JPS,EDG*does not show an exponential explosion effect in map size.The EDG*showed better performance in terms of path smoothness,and collision avoidance.This shows that the EDG*algorithm proposed in this paper can improve the efficiency of path planning and enhance path quality.