Vacuum Comparison Research Articles

Анализ результатов хирургического лечения макулярного разрыва при использовании аутоплазмы, обогащенной тромбоцитами (prp), в сравнении с методом вакуумного сопоставления краев разрыва при помощи канюли с силиконовым наконечником

Purprose. To conduct a comparative analysis of the results of surgical treatment of macular rupture by vacuum comparison of the edges of the rupture using a cannula with a silicone tip, as well as using platelet-enriched autoplasm (PRP) with subsequent air tamponade of the vitreal cavity. Material and methods. A retrospective study of the medical histories of patients treated at the CHF MNTK MHG from 2017 to 2021, with a diagnosis of a through macular rupture, was conducted. The patients were divided into two groups depending on the method of surgical treatment of macular rupture. Patients of group I (control, 44 eyes) with maximum corrected visual acuity before surgery 0.06 ± 0.01; the method of vacuum matching of the rupture edges was performed using a cannula with a silicone tip. In group II (45 eyes) with the maximum corrected visual acuity before surgery 0.09 ± 0.07, platelet-enriched autoplasm (PRP) was used. Results and discussion. The dynamics of visual acuity after surgery in group I after 1 month was 0.1 ± 0.03; after 6 months – 0.1 ± 0.03; after 12 months – 0.1 ± 0.03. In group II, after 1 month, it was 0.26 ± 0.05; after 6 months – 0.3 ± 0.017; after 12 months – 0.5 ± 0.04. When conducting a comparative analysis with the control group, we observed a significant increase in ICOS at the time of 1 and 12 months (p < 0.05). Conclusion. Surgical treatment of macular ruptures using platelet-enriched autoplasm (PRP) is a low-traumatic, highly effective method that allows not only anatomical closure of the macular rupture, but also to improve the functional parameters of the operated eye. Keywords: macular rupture, cannula with silicone tip, PRP, OCT.

Comparison of Vacuum Assisted Closure (VAC) Therapy Versus Conventional Dressing in the Management of Diabetic Foot Ulcer

Background: Debridement of all necrotic, callus, and fibrous tissue is a mainstay of diabetic foot ulcer therapy, with the primary goal of wound closure. The best topical treatment for diabetic foot ulcers is yet unknown. To aid wound healing, a vacuum-assisted closure (VAC) device is used. Objective: To compare the outcome of vacuum-assisted wound closure (VAC) versus conventional wound dressing in diabetic foot ulcers. Material and methods: Study Design: Randomized Control Trial. Setting: Department of Surgery, Services Hospital, Lahore.Duration of Study: 6 months i.e. from-to-Data Collection: Forty patients with diabetic foot ulcer were included. Patients were randomly assigned in two groups. In group A, the dressing was applied by using adhesive drape to create the airtight seal. Conventional group received gauze dressingsoaked in saline once daily. Patients were followed regularly for 2 weeks to check for appearance of granulation tissue. Outcome was determined in terms of appearance of granulation tissue. Results: In VAC group, the mean age of patients was 42.95±9.29years. In conventional group, the mean age of patients was 46.30±9.33years. In VAC group, there were 12 (60%) males and 8 (40%) females. In conventional group, there were 16 (80%) males and 4 (20%) females. In VAC group, the mean duration of wound healing was 7.50±2.82days. In conventional group, the mean duration of wound healing was 10.60±5.55days. The difference was significant (p<0.05). In VAC group, there were 20 (100%) patients who had treatment success. In conventional group, there were 13 (65%) patients who had treatment success while 7 935.0%) did not have complete healing within 2weeks. The difference was significant (p<0.05). Conclusion: Thus, VAC is more successful in achieving granulation of tissues in patients with diabetic foot ulcer as compared to conventional dressing Keywords:Type II diabetes mellitus, diabetic foot ulcerations, Vacuum-assisted wound closure, conventional dressings, Negative pressure wound therapy

A comparison of vacuum and direct contact membrane distillation for phosphorus and ammonia recovery from wastewater

Recovery of ammonia (NH3) and phosphorous (P) from municipal wastewater is important to minimize the environmental impact of their discharge and to comply with the concept of circular economy. Technologies have been established to recover P in form of struvite (MgNH4PO4·6H2O) for its use as a fertilizer. NH3 is usually converted to molecular nitrogen and released to the atmosphere; however, NH3 recovery in form of NH3/H2O mixture is relevant for numerous applications such as manufacturing of cleaning agents, sanitizers and liquid fertilizers. Membrane distillation (MD), a process driven by the partial vapor pressure across a microporous hydrophobic membrane, has demonstrated the potential for concentrating the non-volatiles while, at the same time, recovering volatiles from a solution. Among various configurations of MD, vacuum and direct contact MD (DCMD) have been extensively studied. The current study compares the performance of DCMD and vacuum MD (VMD) for simultaneous recovery of NH3 and P from wastewater in form of NH3/H2O mixture and struvite, respectively. The study finds that while both the configuration are equally effective to concentrate P, the control over removal efficiency of NH3 in the two configurations becomes the bottleneck for struvite recovery under different pH conditions. For wastewater with high pH, VMD almost completely removes NH3 before reaching substantial P concentration, thereby eliminates the possibility of struvite formation. DCMD on other hand, only partly removes NH3 while concentrating P, therefore, for struvite recovery from a high pH wastewater, DCMD is better option. For low pH wastewater, VMD is preferred choice as it recovers NH3 more effectively than DCMD but still leaves ample NH3 in the wastewater for struvite formation.

Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis

Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

Comparison of Vacuum and Aspiration on Phacoemulsification Efficiency and Chatter Using a Monitored Forced Infusion System

To evaluate the effect of vacuum and aspiration rates on phacoemulsification efficiency and chatter using a monitored forced infusion system. Invitro animal study. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. Formalin-soaked porcine lenses were divided into 2mm cubes (tip diameter, 0.9mm). Vacuum levels were tested at 200, 300, 400, and 500mm Hg; aspiration rates at 20, 35, and 50mL/min. Torsional power was set at 60% and intraocular pressure at 50mm Hg. Increasing vacuum increased efficiency regardless of aspiration rates (R(2)= 0.92; P= .0004). Increasing aspiration further increased efficiency when vacuum was at 400 and 500mm Hg (P= .004 for 20 vs 35mL/min, P= .0008 for 35 vs 50mL/min). At 200 and 300mm Hg, efficiency only improved when increasing aspiration to 35mL/min (P < .0001 with 20 vs 35+ 50mL/min). Chatter improved with increasing vacuum, up to 400mm Hg (P= .003 for 200 vs 300mm Hg and P= .045 for 300 vs 500mm Hg). A similar trend of improved chatter was seen with increasing levels of aspiration. Vacuum improved efficiency up to 500mm Hg independent of flow. Flow has an additive effect on efficiency through 50mL/min, when vacuum is at 400mm Hg or higher, and only up to 35mL/min at vacuums less than 400mm Hg. Chatter correlated with both vacuum and flow such that increasing either parameter decreases chatter, up to 400mm Hg with vacuum.

A comparison of vacuum and KBM prosthetic fitting for unilateral transtibial amputees using the Gait Profile Score

The purpose of this study was to compare gait deviations between Kondylen Bettung Münster (KBM) and vacuum prosthetic fitting using the Gait Profile Score (GPS), the Movement Analysis Profile (MAP) and temporal–spatial parameters. Seventeen transtibial amputees that received their prosthesis from the Brazilian governmental health system participated in this study. Twelve of them used KBM prosthetic fitting on their prosthesis and five used vacuum prosthetic fitting. Kinematic and temporal–spatial parameters data were captured by a six-camera Motion Analysis system (Santa Rosa, CA). The results showed that the vacuum group walked faster than the KBM group but the differences in temporal–spatial parameters between them were not significant. The GPS for the intact limb (IL) and the overall GPS differentiated between the groups of prosthetic fitting. Hip flexion/extension and knee flexion/extension were higher in KBM group than in the vacuum group, although only knee flexion/extension for the intact limb revealed significant difference between the groups. In KBM group, the major deviations were in hip flexion/extension for both limbs, knee flexion/extension for both limbs and ankle dorsi/plantar flexion for the prosthetic limb. The vacuum group showed deviations especially in ankle dorsi/plantar flexion for both limbs, knee flexion/extension for the prosthetic limb and hip rotation for the prosthetic limb. Besides, the vacuum group was more symmetrical than the KBM group. This study concluded that subjects who used vacuum prosthetic fitting presented smaller gait deviations and a more symmetrical gait than those who used KBM prosthetic fitting.

Comparison of vacuum and atmospheric deep-fat frying of wheat starch and gluten based snacks

Vacuum frying was compared with atmospheric frying in the development of wheat starch and gluten based snacks in terms of oil uptake, texture, expansion, and color development. The comparison was based on the concept of equivalent thermal driving force (ETDF) (i.e., keeping a constant difference between the oil temperature and boiling point of water at the working pressure). Vacuum fried snacks were observed to absorb lower oil content at all ETDFs and as low as 27% less of atmospherically fried samples and lighter in color. A very strong relationship existed between texture and oil content on one hand; and expansion and oil content on the other hand for fried matrices from both technologies. SEM was used in validating the result. Vacuum frying can be used for the development of acceptable fabricated fried snacks from wheat starch and gluten with lower oil content and acceptable textural and color properties.

Comparison of vacuum and conventional wound dressings for full thickness skin grafts in the minipig model

The aim of this study was to compare vacuum and conventional dressings and to follow revascularization with laser-Doppler spectroscopy and histological evaluations. In six minipigs, full thickness skin grafts were harvested on both sides of the back and transplanted to the contralateral site. One site was covered with a classical cotton dressing, the other with a vacuum dressing. For 10 days, oxygen, haemoglobin, flow and velocity levels were measured by laser-Doppler spectroscopy. Data were analyzed with ANOVA. Histological evaluation included haematoxylin and eosin (H&E) as well as CD31 immunohistochemical staining. Oxygen levels were significantly reduced in the vacuum dressing group compared with the classic dressing group during the first 3 days after transplantation. Haemoglobin levels were slightly, but significantly, higher in the vacuum dressing group over the whole observation period. On the second and third day after transplantation single capillaries were detectable in the histological evaluation. Starting from the fourth day, capillary number increased. Similar results for the classical pressure dressing and the vacuum dressing were observed. The present experimental model provides a standardized and reliable test system for evaluating revascularization of full thickness skin grafts in conjunction with growth factors and other enhancers of revascularization.

Comparison of vacuum and high pressure evaporated wood hydrolyzate for enthanol production by repeated fed-batch using flocculating Saccharomyces cerevisiae

With the aim of increasing the sugars concentration in dilute-acid lignocellulosic hydrolyzate to more than 100 g/l for industrial applications, the hydrolyzate from spruce was concentrated about threefold by high-pressure or vacuum evaporations. It was then fermented by repeated fed-batch cultivation using flocculating Saccharomyces cerevisiae with no prior detoxification. The sugars and inhibitors concentrations in the hydrolyzates were compared after the evaporations and also fermenta-tion. The evaporations were carried out either under vacuum (VEH) at 0.5 bar and 80°C or with 1.3 bar pressure (HPEH) at 10 7.5 °C, which resulted in 153.3 and 164.6 g/l total sugars, respectively. No sugar decomposition occurred during either of the evaporations, while more than 96% of furfural and to a lesser extent formic and acetic acids disappeared from the hydrolyzates. However, HMF and levulinic acid remained in the hydrolyzates and were concentrated proportionally. The concentrated hydrolyzates were then fermented in a 4 l bioreactor with 12-22 g/l yeast and 0.14-0.22 h-1 initial dilute rates (ID). More than 84% of the fermentable sugars present in the VEH were fermented by fed-batch cultivation using 12 g/l yeast and initial dilution rate (ID) of 0.22 h-1, and resulted in 0.40±0.01 g/g ethanol from the fermentable sugars in one cycle of fermentation. Fermentation of HPEH was as successful as VEH and resulted in more than 86% of the sugar consumption under the corresponding conditions. By lowering the initial dilution rate to 0.14 h-1, more than 97% of the total fermentable sugars were consumed, and ethanol yield was 0.44±0.01 g/g in one cycle of fermentation. The yeast was able to convert or assimilate HMF, levulinic, acetic, and formic acids by 96, 30, 43, and 74%, respectively.

Ab Initio Modeling of Glycosyl Torsions and Anomeric Effects in a Model Carbohydrate: 2-Ethoxy Tetrahydropyran

A range of ab initio calculations were carried out on the axial and equatorial anomers of the model carbohydrate 2-ethoxy tetrahydropyran to evaluate the level of theory required to accurately evaluate the glycosyl dihedral angle and the anomeric ratio. Vacuum CCSD(T)/CBS extrapolations at the global minimum yield Δ E = E equatorial − E axial = 1.42 kcal/mol. When corrected for solvent (by the IEFPCM model), zero-point vibrations and entropy, Δ G 298 = 0.49 kcal/mol, in excellent agreement with the experimental value of 0.47 ± 0.3 kcal/mol. A new additivity scheme, the layered composite method (LCM), yields Δ E to within 0.1 kcal/mol of the CCSD(T)/CBS result at a fraction of the computer requirements. Anomeric ratios and one-dimensional torsional surfaces generated by LCM and the even more efficient MP2/cc-pVTZ level of theory are in excellent agreement, indicating that the latter is suitable for force-field parameterization of carbohydrates. Hartree-Fock and density functional theory differ from CCSD(T)/CBS for Δ E by ∼1 kcal/mol; they show similar deviations in torsional surfaces evaluated from LCM. A comparison of vacuum and solvent-corrected one- and two-dimensional torsional surfaces indicates the equatorial form of 2-ethoxy tetrahydropyran is more sensitive to solvent than the axial.

Phacodynamics: An Aspiration Flow vs Vacuum Comparison

To compare actual flow and the vacuum necessary to generate that flow for the Advanced Medical Optics Sovereign (Advanced Medical Optics, Santa Ana, California, USA) and the Alcon Legacy (Alcon, Fort Worth, Texas, USA) phacoemulsification machines. In vitro laboratory study. Flow was collected and machine indicated vacuum noted from 12 ml/min to 40 ml/min in 2 ml/min steps (20-gauge). Nineteen and 20-gauge tips were also compared. Machine indicated vacuum was converted to actual tip vacuum. Legacy flow (102.4 +/- 3.8% of indicated) was significantly more than Sovereign (96.5 +/- 3.9%; P < .0001). 20-gauge flow was less than 19-gauge flow (96.1% vs 98.6% of indicated, P < .0001). Sovereign had less unoccluded vacuum (70.3 +/- 3.2 mm Hg) than Legacy (89.4 +/- 1.2 mm Hg) at 36 ml/min of flow (P < .0001 for 26 to 36 ml/min of flow). There is unoccluded vacuum at the phaco tip of these systems at 14 ml/min, of flow and at 40 ml/min, this was 112.0 mm Hg for the Legacy.

IRAS study of formic acid decomposition on [formula omitted] surface: comparison of vacuum and catalytic conditions

Decomposition of formic acid on an NiO(111) surface grown on Ni(111) under vacuum and catalytic conditions was investigated by infrared reflection absorption spectroscopy. It was found that adsorbed formic acid under ultra-high vacuum conditions formed bidentate formate which was tilted along the molecular plane. Formic acid decomposed catalytically over the NiO(111) surface at 423 K and 10 −3 Pa of formic acid with small activation energies of 22 and 16 kJ mol −1 for dehydrogenation and dehydration, respectively. Both monodentate and bidentate formate were observed on the surface under the catalytic condition. The monodentate formate was identified as an intermediate of decomposition from the similarity between the pressure dependence of the coverage and that of the decomposition rate estimated from the partial pressures of the products. The bidentate species observed under the catalytic condition was oriented normal to the surface in contrast to the titled orientation in vacuum, indicating structural change of the surface.

Comparison of vacuum and pressure-assisted sintering of TiB2-Ni

A relatively new generation of cermet materials, based on TiB2-Ni, has been investigated. These borides currently are being examined for industrial applications with the aim of exploiting their excellent wear resistance. Optimization of the liquid-phase sintering process for a TilB2-Ni composition was studied. The mechanical properties of cermet materials prepared using vacuum and pressure sintering techniques were determined. Criteria for optimal sintering conditions were established according to hardness, strength, and fracture toughness properties.

Comparison of Vacuum and Belt Seeders for Vegetable Planting

Two precision vacuum seeders were compared with a precision belt seeder in laboratory tests using seeds from five vegetable crops (cabbage, carrot, cucumber, onion, and spinach). There were no significant differences in seed placement uniformity with carrot or onion seed. One of the vacuum seeders delivered spinach seed most uniformly. The belt seeder delivered cabbage seed most uniformly. With cucumber seed, the two vacuum seeders resulted in much better uniformity than the belt seeder. Cucumber seed is flat and elongated, thus it is difficult to singulate with a belt seeder. Each vacuum seeder was compared independently with the precision belt seeder in replicated field tests of vegetable crops (cabbage, broccoli, cantaloupe, and carrot). In the field, there were few differences in stand or yield.

Packaging Venison for Extended Chilled Storage: Comparison of Vacuum and Modified Atmosphere Packaging Containing 100% Carbon Dioxide

Thirty red deer (Cervus elaphus) stags were slaughtered at three deer slaughter premises (plants A, B, and C) to determine the effects of initial microbial flora on the quality of chilled venison loins stored using three packaging methods: vacuum packaging (VP), modified atmosphere packaging using an ultra-high barrier outer barrier film (CO2-UHB), and modified atmosphere packaging using a dual aluminized polyethylene outer barrier film (CO2-MPET), all of which were stored for 6, 12, and 18 weeks at −1 ± 3°C. Carcasses slaughtered in plant B had higher aerobic plate counts than those killed at either plants A or C. Location of slaughter had little effect on loin quality except for drip loss, pH and anaerobic and lactic acid bacteria counts. Oxygen levels increased in the modified atmosphere packages (P<0.05) during storage from 12 to 18 weeks (CO2-UHB, 1%; CO2-MPET, 0.05%). Loins packaged in CO2 -UHB exhibited less acceptable surface color than meat packaged in CO2 -MPET or VP. Aroma, flavor, texture, and acceptability scores decreased (P<0.05) when loins were stored over 12 weeks regardless of packaging method. pH values of loins packaged in modified atmosphere packs were lower (P<0.05) than those in VP. The regression relationship between percent drip loss and pH was given by % drip = 39.1–6.49 [Standard error (SE) 1.52] pH. Acceptable display color of steaks cut from the loins, regardless of treatment, decreased as loins were stored from 6 to 18 weeks. These results suggest that vacuum packaged venison loins resulted in meat of acceptable quality after 12 and 18 weeks of chilled storage, and that modified atmosphere packaging contributed no additional benefit.

Minimum analysis time in capillary gas chromatography vacuum‐ versus atmospheric‐outlet column operation

AbstractPrevious studies on open tubular column operation at vacuum outlet vs. atmospheric outlet pressures focused on comparisons of given columns, or comparisons of columns with the same inner diameters. It was demonstrated that, for a given separation problem, vacuum outlet operation of columns with a constant i. d. always yields the shortest analysis times (under minimum plate height conditions).In this paper, the comparison of vacuum vs. atmospheric outlet operation is broadened to columns with different dimensions. A general equation for the gain in speed of analysis by vacuum outlet operation of any column, as compared to atmospheric outlet operation of all possible open tubular columns with the same maximum plate number is presented. The resulting equation is further evaluated for thin film columns of different dimensions.It appears that vacuum outlet operation is beneficial only, in terms of speed of analysis, if low maximum plate numbers are required. The gain in speed of analysis is more pronounced for wide‐bore than for narrow‐bore columns.

A Comparison of Vacuum and SF6 Technologies at 5-38 kV

Comparisons are made between characteristics of vacuum and SF6 (sulfur hexafloride) interrupters as a result of comparative tests, and papers relating to the subject are reviewed. Subjects are discussed which are not currently defined by existing industry standards but which are important to the user. At this point in time, vacuum tends to favor short range economics and yields longer life for highly repetitive operations at load break current levels. SF6 technology tends to increase system reliability due to a number of inherent characteristics.

Microstructural and environmental effects on fretting fatigue

Fretting fatigue characteristics of two microstructures of a .40 .50 carbon steel are discussed in terms of the relative effects of mechanical and corrosive damage. Comparison of vacuum and laboratory air fretting fatigue data of each microstructure verifies the hypothesis that the mechanical damage incurred during the fretting process is of more consequence than the chemical damage due to oxide formation. A microstructural effect is evidenced in that the region of data over which decreases in life become significant is different for each microstructure. The microstructures investigated were a ferrite-pearlite structure in the as-received sheet form and a tempered martensite structure of higher strength.

A Comparison of Vacuum and Whole-Plant Methods for Sampling Predaceous Arthropods on Cotton

A survey of predaceous arthropods in California cotton ( Gossypium hirsutum L.) fields was conducted over a 3-year period as part of an evolving pest management program. The primary objective of the survey was to develop an efficient method for sampling arthropods in relation to larval populations of the bollworm, Heliothis zea (Boddie). Samples were taken with a whole plant extraction method, and at 2 times of day and by 2 methods with the D-VAC® vacuum machine. Vacuum sample data were highly erratic. Data from whole plants had a high man-hours requirement. None of the methods tested is suitable for use in pest management programs. Data from whole plant samples were used to estimate seasonal occurrence of the more abundant predator species. These were the minute pirate bug, Orius tristicolor (White); big-eyed bugs, Geocoris spp. ( G. punctipes (Say) and G. pallens (Stal)); damsel bugs, Nabis spp. mainly americoferus Carayan; green lacewings, Chrysopa spp., mainly carnea Stephens; the notoxus beetle, Notoxus calcaratus Horn; and a complex of spiders. Estimates of their seasonal abundance are given on a per hectare basis. Comparisons were made between the numbers of each predaceous species and numbers of bollworms and cabbage loopers, Trichoplusia ni (Hubner). None of the predaceous species related numerically to bollworms, or to cabbage loopers, the only abundant lepidoptera pest species found in the study areas. The numbers of Geocoris appear to correlate with the abundance of cotton blossoms. The data suggest this species may be feeding principally either on the cotton plant and/or on insect(s) of minor economic importance whose availability as prey depends on the occurrence of a suitable substance in the cotton plant.

A Comparison of Vacuum and Steam Distillation for Determining the Volatile Acidity of Evaporated Milk

Summary 1. A method of determining formic acid and volatile acid values in heated milk by means of vacuum distillation at constant volume is presented. Results of experiments to determine the recovery of added formic acid from sterilized evaporated milk by the steam and vacuum distillation procedures are discussed. 2. The formic acid content of reconstituted evaporated milk averaged about 32 mg./l. by steam distillation and about 40 mg./l. by vacuum distillation. 3. The total volatile acid content of reconstituted evaporated milk, expressed as formic acid, averaged 134 mg./l. by steam distillation and 70 mg./l. by vacuum distillation. 4. The vacuum and steam distillation procedures both gave satisfactory recovery of added formic acid from sterilized evaporated milk by the gravimetric method. 5. There was no evidence of production of formic acid during steam distillation as far as the accuracy of the methods could detect. 6. Titrations of volatile acids on the steam distillates were considerably higher than on the vacuum distillates. The difference could be due to continuous evolution of carbon dioxide from the milk during steam distillation, the more rapid distillation rate of butyric and caproic acids with steam, and/or splitting of glycerides of fatty acids during steam distillation. 7. The addition of formic acid to the milk appeared to reduce the amount of volatile acids not formic obtained by steam distillation. 8. The vacuum distillation showed an advantage over steam distillation where a consideration of the total volatile acids in the distillate was desired.