Effects Of Various Lengths Research Articles

Influence of PMMA brushes grafted from GO on rheological properties of PMMA/SAN immiscible blend in shear and elongation flow

In real technological processes, both shear and elongational flow is present. The material properties may differ significantly under both types of flow. Hence, they both define the final morphology and thus properties of the materials. In this work, the morphology of immiscible blends containing polymer hybrid particles was related to extensional rheological properties for the first time. The effect of various lengths of polymer brushes grafted from graphene oxide particles (GO) surface was investigated. As a polymer matrix the immiscible blend of poly(methyl methacrylate)/styrene-co-acrylonitrile (PMMA/SAN) was used. Thus the poly(methyl methacrylate) (PMMA) brushes grafted from GO (GO-g-PMMA) with various number average molar masses (Mn) of PMMA brushes with respect to chain entanglement limit of freely dispersed PMMA were prepared. The extensional rheological properties were affected by Mn of PMMA brushes, while the rheological properties in shear were unchanged. Transmission electron microscopy revealed the compatibilization effect for short densely grafted brushes with Mn of 10,300 g/mol, as smaller domains were observed. On the contrary, the higher Mn PMMA brushes facilitated coalescence. With increasing length of brushes, the elongational viscosity at low elongation rates (∼< 0.1 s−1) decreased, which facilitated the coalescence. The increase of viscosity at higher elongation rates (∼> 0.1 s−1) was not sufficient enough to cause fiber breakup and thus elongated domains were formed.

Real Time In Vivo Evaluation of Mitochondrial Activity and Brain Functions during Ischemic Stroke

More than 50% of total energy consumed by the brain is utilized by active transport processes which are responsible for keeping the ionic homeostasis in the brain. Under an ischemic condition, energy availability is limited, and, as a result, inhibition of the ion pumps is unavoidable. The initial consequence of such inhibition is a gradual accumulation of K+ in the extracellular space leading to a second phase of the ischemic depolarization phenomenon. During ischemic depolarization, extracellular K+ will increase 15-20-fold, while extracellular Ca2+ is decreasing 10 fold. Another optional effect of mild ischemia is the development of Cortical Spreading Depression due to the leakage of K+ into the extracellular space. The Mongolian gerbil provides a very useful animal model to study the effects of ischemia on brain functions. The aims of the study were as follows: (1) To elucidate the mechanism behind the development of ischemic depolarization or cortical spreading depression under unilateral and bilateral carotid artery occlusion. (2) To correlate the kinetics of the recovery processes to the level of ischemia. We tested the correlation between energy depletion level (evaluated by intramitochondrial NADH redox state and Cerebral Blood Flow) and the development of ischemic depolarization or cortical spreading depression (evaluated by extracellular K+, H+, Ca2+, DC potential and 366 nm reflectance changes) under partial and complete ischemia using the multiparametric monitoring system. The results could be summarized as follows: (1) Under bilateral occlusion, in all gerbils the ischemic depolarization was recorded within 1-2 min. (2) Under unilateral occlusion, the level of ischemia obtained was significantly smaller and led to the ischemic depolarization in about 60% of the gerbils. (3) The K+ leakage during the ischemic depolarization had an 'all or none' nature in terms of maximal K÷ levels and time to reach it. (4) The main effect of various lengths of bilateral occlusion was on the recovery time of extracellular K+ level. (5) Cortical spreading depression develop in most cases during the recovery from the ischemic event when ischemic depolarization was not recorded under the ischemic episode.

Reduction of Seepage Risks by Investigation into Different Lengths and Positions for Cutoff Wall and Horizontal Drainage (Case Study: Sattarkhan Dam)

Seepage from the earth dam’s body reduces the amount of water in the dam’s reservoir and threatens its stability. In this paper, the earth‐type Sattarkhan Dam on the Aharchai River has been investigated. In this regard, the SEEP/W model from the GeoStudio 2018 software suite was used for modeling. This study examines the effects of various lengths and positions of cutoff wall and horizontal drainage on seepage, uplift pressure, and exit gradient. Increasing the length of the cutoff wall reduces seepage in both sections, with a more significant effect on Section 2; it also decreases the uplift pressure and the exit gradient. Changing the position of the cutoff wall has a significant effect on seepage fluctuations in Section 1 but has no effect on seepage in Section 2; in positions 2 to 7, the uplift pressure values are nearly identical, and the exit gradient is most significant at position 1 and least at position 2. Increasing the horizontal drainage’s length increases seepage, reduces uplift pressure, and increases the exit gradient. The closer proximity of the horizontal drainage position to the dam’s core increases seepage and decreases uplift pressure and exit gradient. Finally, it is concluded that the construction of a cutoff wall and horizontal drainage with appropriate lengths and positions reduces risk and improves the stability of earth dams.

Investigating the motions’ characteristics of a towed barge in extreme heading wave

A towed barge is one of the typical sea transportation systems that is basically composed of towing and towed ships connected to each other by a tow rope. During a towing operation exposed to rough sea condition, the risk of collision and breakage of a tow rope may be high and the consequences serious. This paper describes an experimental investigation of a towed barge’s motions in heading waves. The effects of various lengths and the configuration of tow ropes incorporated with various loading conditions of the towed barge have been taken into account. Here, three tow-rope lengths were used, namely 1L, 1.5L, and 2L; meanwhile, the two tow-rope configurations i.e., Straight-Tow (ST) and V-Tow (VT) models were applied and incorporated with 50% and 100% of the loading conditions of the towed barge. Regardless of the tow-rope models of ST and VT, the results revealed that the towed barge’s motion responses were generally proportional to the increase of the towline lengths and the towed barge’s loading conditions. It should be noted here that the VT model with 1L tow rope length in the full loaded condition has less RAO of her heave and pitch motions as compared to the other towing arrangements. Merely, this research investigation provides very useful guidance on a ship towing navigation in waves.

Polyacrylamide brushes with varied morphologies as a tool for control of the intermolecular interactions within EPDM/MVQ blends

The specific interactions between polyacrylamide brushes composed of polyacrylamide chains tethered to montmorillonite particles (Mt-g-PAm) and the individual components of immiscible ethylene-propylene-diene modified with sorbic acid (EPDM) and methyl vinyl silicone (MVQ) blends were studied. The effect of various lengths of PAm chains and their grafting density on montmorillonite (Mt) surface was investigated.It was determined that, due to interactions generated within the system through carboxyl and amide groups the brush particles were selectively located at the EPDM/MVQ interphase and in the EPDM phase. Furthermore, the longer PAm chains resulted in an increase of the glass transition of EPDM, unification of blend morphology, and the reduction of crystallinity of the MVQ phase. Therefore, precisely designed polymer brushes could be considered as novel functional compatibilizers, that provide a new tool for the future material designing.

EFFECT OF WATER DEPRIVATION ON NUTRIENT DIGESTIBILITY, NITROGEN RETENTION, AND WATER EXCRETION IN YANKASA SHEEP AND MARADI GOATS

The effects of various lengths of water deprivation on nutrient digestibility were studied with Yankasa sheep and Maradi goats fed on a diet consisting grass hay (Andropogon gayanus) and 40% concentrate. The water-restricted animals consumed less dry matter than normally-watered animals. The digestibility coefficients of the different nutrients were apparently though not significantly higher in water-restricted animals. Mean faecal and urinal nitrogen excretion reduced with water deprivation. Faecal moisture content and urine output reduced with water deprivation. Maradi goats conserved water better than Yankasa sheep by producing drier faeces, and less- urine volume.

The effect of various lengths of pores and throats on the formation resistivity factor

Pore geometry, quantified by the length and size of the pore space, affects the electrical resistivity of the porous media. However, the length described by the geometrical tortuosity and pore topology effect on the resistivity of the model does not thoroughly consider the existing pore geometrical models, which only investigate the pore size, throat length and throat size of the models. A modified capillary model including a pore body and several throats derived the formation factor from the coordination number, the cross-sectional area ratio and geometrical tortuosity of the pores and throats in the model. The derived relationship between the formation factor and porosity of the capillary model compared with the formation factor versus porosity for the various rock types was shown in a plot. The geometrical tortuosity of each rock type almost followed the electrical tortuosity of the related rock type, and the electrical tortuosity was larger than the geometrical tortuosity caused by the variation in the size of the pore and throat. For low porosity, the resistivity of the real porous media was lower than the resistivity of the Archie equation due to the low values of the pore-to-throat cross-sectional area ratio and geometrical tortuosity. The sandstones and interparticle carbonates presented a porosity exponent close to 2.0 and an electrical tortuosity from 1.5 to 4.0 on the plot of the porosity exponent versus electrical tortuosity. The fractured carbonate showed a porosity exponent from 1.0 to 1.6 and an electrical tortuosity ranging from 1.0 to 3.0, while the vuggy carbonates were widely distributed, with a porosity exponent larger than 2.0 and an electrical tortuosity ranging from 2 to 8. This new model correlates the formation factor and porosity to the combination of the coordination number with the geometrical tortuosity and the throat and pore cross-sectional area ratios, thus enhancing the understanding of the pore geometry and topology effect on the electrical resistivity of a porous media with various pore types.

Pertumbuhan Bibit Buah Naga (Hylocereus polyrhizus) pada Berbagai Panjang Stek dan Komposisi Media Tanam

Dragon fruit is one of the cactus plants which is quite popular because of its sweet taste and unique and interesting shape. Propagation of dragon fruit seeds is usually done by cuttings and one of the problems in the supply of dragon fruit seeds is the planting medium. This study aims to determine (i) the effect of the interaction of various cuttings lengths and composition of the planting medium, (ii) the effect of various lengths of cuttings, (iii) the influence of various plant media compositions, (iv) the best interactions between various cuttings and composition of planting media, (v ) the best length of cuttings and (vi) the best media composition in dragon fruit cultivation. This study was conducted in Haur Gading Village, Batang Alai Utara District, Hulu Sungai Tengah Regency from May-August 2018, using Factorial Randomized Block Design (RBD) 2 factors. The first factor is the length of cuttings with 4 levels: p1 = 35 cm, p2 = 40 cm, p3 = 45 cm, p4 = 50 cm. The second factor is the composition of the planting medium with 3 levels: k1 = 1.5 kg of soil: 0.0 kg wallet dirt fertilizer: 1.5 kg of sand, k2 = 1.0 kg of soil: 1.0 kg of wallet dirt fertilizer: 1, 0 kg of sand, k3 = 0.5 kg of soil: 1.5 kg wallet dirt fertilizer: 1.5 kg of sand. The results showed that the interaction of the length of cuttings with the composition of the planting medium had no effect on growth, while the single length factor of the cuttings had no effect on all observation variables except the shoot length had a significant effect on week 12 WAP and the composition of planting media influenced the growth of dragon fruit seeds.

Effects of various lengths of hypoglossal nerve resection on motoneuron survival

We employed stereological analyses for whole quantification of hypoglossal (XII) motoneurons in adult rats that received varying degrees of resection of the XII nerve. Various lengths of nerve gaps (0.0–13.3 mm) were made at the main trunk of the unilateral XII nerve, and the total number of XII neurons on the injured and uninjured sides was counted 12 weeks after nerve resection. The stereologically estimated total number of XII neurons decreased after various lengths of nerve resection, and survival rates ranged from 34.4% to 87.1%. Statistically significant negative correlations were observed between increasing length of the resected nerve and decreasing XII neuron survival. It was concluded that the total number of XII neurons decreased after nerve resection and that survival rates of XII neurons were related to distances between resected nerve stamps.

Convective heat transfer in a porous enclosure saturated by nanofluid with different heat sources

Abstract The present study is proposed to investigate the effects of various lengths and different locations of the heater on the left sidewall in a square lid-driven porous cavity filled with nanofluid. A higher temperature is maintained on the left wall where three different lengths and three different locations of the heat source are considered for the analysis. The right wall is kept at a lower temperature while the top and bottom walls, and the remaining portions of the heated wall are adiabatic. The governing equations are solved by finite volume method. The results show that among the different lengths of the heat source, an enhancement in the heat transfer rate is observed only for the length LH = 1/3 of the heat source. In the case of location of the heat source, the overall heat transfer rate is increased when the heat source is located at the top of the hot wall. For Ri = 1 and 0.01, a better heat transfer rate is obtained when the heat source is placed at the top of the hot wall whereas for Ri = 100, it occurs when the heating portion is at the middle of the hot wall. As the solid volume fraction increases, the viscosity of the fluid is increased, which causes a reduction in the flow intensity. An addition of nanoparticles in the base fluid enhances the overall heat transfer rate significantly for all Da considered. The permeability of the porous medium plays a major role in convection of nanofluid than porosity. A high heat transfer rate (57.26%) is attained for Da = 10−1 and χ = 0.06.

Electron Transfer Kinetics of a Series of Bilayer Triphenylamine–Oligothiophene–Perylenemonoimide Sensitizers for Dye-Sensitized NiO

A series of triphenylamine (TPA)–oligothiophene–perylenemonoimide (PMI) molecules, denoted as the BH dyes, which mimic membrane lipid bilayers to enable stable operation of dye-sensitized NiO photocathodes under extremely acidic (pH = 0) conditions, have been recently reported for solar hydrogen production. In this work, we systematically study the photophysical properties of the BH series molecules with various lengths of π-linkers in solution via density functional theory (DFT) calculations and time-resolved spectroscopic techniques. When dissolved in DMF, the molecules undergo ultrafast intramolecular charge transfer within 1 ps upon photoexciation. The charge-separated state then recombines within tens of picoseconds. The electron transfer kinetics of dye-sensitized mesoporous NiO photocathodes exhibit both fast and slow charge recombination processes (70 ps and 4.5 μs, respectively, for BH4). The effect of various lengths of π-linkers is modeled with a spatial attenuation factor of 0.20 A–1 with a lo...

The influence of diameter of vortex finder on cyclone collection efficiency

Cyclones, which are used to separate particles from particle–gas mixtures by spinning movement of centrifugal forces, are stationary pieced devices, main advantages of which are their simplicity and also operability under heavy conditions such as high temperature and high pressure. From an engineering point of view, there are two important parameters in cyclones, namely the cyclone pressure loss and particle collection efficiency. In this work, three different vortex finders' diameters of 80, 120, and 160 mm were designed and fabricated to investigate experimentally the effects of various lengths of vortex finders, inlet velocities and concentrations of inlet particles on particle collection efficiency of preheat cyclones. Increases in all the operating parameters led to increases in the collection efficiency of all cyclones. Also, the experimental study clearly pointed out a critical diameter of vortex finder of 120 mm. © 2014 American Institute of Chemical Engineers Environ Prog, 2014 34: 669–673, 2015

Longitudinal Analysis of Calorie Restriction on Rat Taste Bud Morphology and Expression of Sweet Taste Modulators

Calorie restriction (CR) is a lifestyle intervention employed to reduce body weight and improve metabolic functions primarily via reduction of ingested carbohydrates and fats. Taste perception is highly related to functional metabolic status and body adiposity. We have previously shown that sweet taste perception diminishes with age; however, relatively little is known about the effects of various lengths of CR upon taste cell morphology and function. We investigated the effects of CR on taste bud morphology and expression of sweet taste-related modulators in 5-, 17-, and 30-month-old rats. In ad libitum (AL) and CR rats, we consistently found the following parameters altered significantly with advancing age: reduction of taste bud size and taste cell numbers per taste bud and reduced expression of sonic hedgehog, type 1 taste receptor 3 (T1r3), α-gustducin, and glucagon-like peptide-1 (GLP-1). In the oldest rats, CR affected a significant reduction of tongue T1r3, GLP-1, and α-gustducin expression compared with age-matched AL rats. Leptin receptor immunopositive cells were elevated in 17- and 30-month-old CR rats compared with age-matched AL rats. These alterations of sweet taste-related modulators, specifically during advanced aging, suggest that sweet taste perception may be altered in response to different lengths of CR.

Effect of heating location and size on MHD mixed convection in a lid‐driven cavity

PurposeThe main objective of the present study is to investigate the effects of various lengths and different locations of the heater on the left sidewall in a square lid‐driven cavity.Design/methodology/approachThe non‐dimensional equations are discretized by the finite‐volume method. The upwind scheme and the central difference scheme are implemented for the convection and the diffusion terms, respectively.FindingsOn increasing the Richardson number, the overall heat transfer is increased whether the length and the location of the heater is considered or not. Among the various lengths of the heater considered, the total heat transfer is better only for the length LH=1/3 of the heater if it is extended from top or bottom of the cavity. In the case of location of the heater, the average heat transfer enhances for center location of the heater. Existence of the magnetic field suppresses the convective heat transfer and the fluid flow.Practical implicationsThe results can be used in the cooling of electronic devices and heat transfer improvement in heat exchangers.Originality/valueThe numerical results obtained here focus on the detailed investigation of flow and temperature field in a discretely heated lid‐driven square cavity. The findings will be helpful in many applications such as heat exchangers and cooling of electronic devices.

Effect of Various Lengths of Single Phase Starvation on Compensatory Growth in Rainbow Trout under Summer Conditions (Oncorhynchus mykiss)

This study was conducted to determine the effects of various lengths of starvation periods on following compensatory growth (CG) in rainbow trout under summer conditions (18.1°C and day length of 12.5-14.5 hours). Five treatments with triplicate tanks were as follows: control (C) fed to satiation over 84 days; one (S1), two (S2), three (S3), and four (S4) weeks of starvation; and then refeeding for the remaining eight weeks of the experiment. Starvation periods induced hyperphagia during refeeding but only S1 and S2 were able to catch up with C. Repeated measures of analysis of variance suggested a convergence in body mass but not in body length (structure). Organo-somatic indices of the starvation groups were significantly reduced at the end of starvation periods and restored to levels of the control fish within the first two weeks of the refeeding period. Broadly speaking, starvation longer than one week significantly reduced apparent digestibility of dry matter, lipid, and energy compared with the control group but did not affect protein and ash, and a complete recovery in the digestibility coefficients occurred within two weeks of satiation feeding. There was a linear increase in body moisture and a decrease in lipid and lipid/lean body mass ratio with the severity of starvation periods, but these divergences largely disappeared at the end of refeeding. During the starvation period, the protein synthesis rate (estimated using RNA/DNA ratio in the muscle and liver) reduced but in subsequent refeeding period, it increased in starved fish. The findings of the present experiment suggest that an application of single starvation episodes to elicit CG as a management tool in summer conditions should not be longer than two weeks.

Moisture distribution in drying ordinary and high performance concrete cured in a simulated hot dry climate

Adequate moisture is very important during early age of portland cement concrete. The Single Point Magnetic Resonance Imaging technique was used to study the effects of various lengths of moist curing, and the use of curing compound, on the amount and distribution of evaporable water during drying of ordinary and high performance concrete. The specimens subjected to six different curing regimes, were cast in triplicate for a total of 72. After moist curing at 38°C, the specimens were subjected to uniaxial drying in an environmental chamber at 38°C and 40% relative humidity that simulated hot dry climate conditions. As the specimens were drying, Magnetic Resonance Imaging was used to study the evaporable water distribution, non-destructively and with millimetric resolution. The Magnetic Resonance Imaging profiles indicated a reduced moisture loss with increasing length of moist curing. Extended moist curing was especially beneficial for the two self-compacting concrete mixtures, particularly for the cover concrete. In all mixtures the use of curing compound was only marginally better than one day moist curing, but was significantly better than air curing, particularly for the cover concrete. The moisture diffusivity was evaluated from the transient moisture distribution profiles using the Boltzmann transformation method. The results indicated a strong dependence of the moisture diffusivity on the moisture content when above 80% saturation, whereas below this value it remains almost constant. The moisture diffusivity is significantly reduced with increased moist curing period.

The effect of length and concentration of glass fibers on the mechanical properties of an injection- and a compression-molded denture base polymer

Statement of problem Fiber-reinforcement has been used to overcome the mechanical limitations of denture base polymers. One major difficulty in the use of fiber reinforcement has been the addition of fibers during conventional processing methods. Purpose This study evaluated the effect of various lengths and concentrations of chopped E-glass fiber-reinforcement on the transverse strength, modulus of elasticity, and impact strength of injection and compression-molded polymethyl methacrylate based denture base polymer. Material and methods Test specimens (n=10) of 4-, 6-, and 8-mm fiber length and 1%, 3%, and 5% weight fiber concentrations were prepared with either an injection or a compression-molded processing method. Denture base polymer specimens without any fiber reinforcement were used as control for both processing methods. Transverse strength test specimens (65 × 10 × 2.5 mm) were stored in water bath at 37°C for 2 weeks. The transverse strength (MPa) and modulus of elasticity (GPa) was measured with the 3-point bending test. Impact strength (kJ/m 2) test specimens (60 × 7.5 × 4 mm) were tested with the Charpy-type pendulum impact test setup. The data were analyzed with multifactorial analysis of variance and Tukey post hoc tests (α=.05). Results Injection-molded fiber-reinforced groups showed significantly higher transversal strength, elastic modulus, and impact strength compared with compression-molded groups ( P < .001). In the injection-molded groups, fiber concentration increased all mechanical properties tested ( P < .05), but fiber length only increased transverse strength and modulus of elasticity ( P < .05). In the compression molded groups, fiber concentration affected modulus of elasticity and impact strength significantly ( P < .05), but fiber length did not show any significant effect on the mechanical properties tested ( P > .05). Conclusion The transverse strength, elastic modulus and impact strength of injection-molded denture base polymer increased significantly with the use of chopped E-glass fibers, whereas the effect was not significant with the compression-molded polymer.

The Physiological Effect of Graded Compression Stockings on Blood Flow in the Lower Limb: An Assessment with Colour Doppler Ultrasound

Objectives: To assess the physiological effect of low-pressure graded compression stockings (GCS) on the blood flow of the lower limb with the use of colour Doppler. Design: A randomised controlled study. Setting: X-ray Department in a teaching hospital. Patients: Forty-five healthy, adult, voluntary subjects. Method: Subjects were randomised into three groups to either wear thigh- or knee-length GCS of the same type or no stockings. The diameter and cross-sectional area of the femoral and popliteal veins and the peak venous velocities were measured with colour Doppler before the application of GCS and after 20 min bed rest with the stockings in situ. Results: Measurements showed a significant increase of the peak velocity in the femoral vein with thigh-length GCS ( p&lt;0.002). There was a significant decrease of the popliteal vein diameter and cross-sectional area with thigh-length GCS ( p&lt;0.05). There was no significant change in the knee-length GCS group and the control group, in which patients did not wear stockings. A paired t-test was used to determine the significance of the changes. Conclusions: Thigh-length GCS have an effect of increasing venous peak velocity in the femoral vein, hence decreasing venous stasis. Furthermore, they decrease the dilatation of the popliteal vein, which may reduce the risk of intimal tears occurring, which may contribute to venous thrombogenesis. Other methods can given more information in assessing the effect of various lengths of stocking on venous stasis.

Exposure of cartilage to a fibronectin fragment amplifies catabolic processes while also enhancing anabolic processes to limit damage.

The addition of fibronectin fragments to cultured cartilage causes an initial suppression of proteoglycan synthesis, induction of matrix metalloproteinases, and resultant decrease in proteoglycan content by about 50% during the first few days in culture. Because the proteoglycan loss appears to be limited, we investigated whether the fibronectin fragments induce anabolic responses that might counter the damage. The effects of various lengths of exposure of cultured cartilage to the fibronectin fragment on proteoglycan content, proteoglycan synthesis rates, stromelysin-1 release, and tumor necrosis factor-alpha, interleukin-1alpha, and interleukin-6 release were investigated. The results showed that about 7 days of exposure of cultured cartilage to the fibronectin fragment was required for maximal cytokine release, proteoglycan depletion, and stromelysin-1 release. However, nearly maximal suppression of proteoglycan synthesis occurred within 1 day of the addition of the fibronectin fragment and, after its removal, the rates increased to supernormal levels. Decreasing exposure to 3 days caused only a small decrease in cartilage proteoglycan content, although stromelysin-1 release still occurred. Decreasing exposure to 1 day caused an immediate increase in proteoglycan synthesis and an increase to supernormal proteoglycan contents. The effect of first treating cartilage with the fibronectin fragment for various periods and then allowing a recovery was to make the cartilage more resistant to secondary exposures. This study shows that cartilage damage can be caused by short exposures to the fibronectin fragment and that exposures either optimal or suboptimal for damage additionally amplify anabolic processes to make the cartilage resistant to further damage and, thus, condition it against pending amplification of damage.

Comparison of the effects of various lengths of synthetic human parathyroid hormone-related peptide (hPTHrP) of malignancy on bone resorption and formation in organ culture

Parathyroid hormone-related peptide (PTHrP) has been shown to be the patthogenic agent in humoral hypercalcemia of malignancy (HHM), but the molecular forms that are secreted have not been fully characterized. PTHrP 1–34 has effects similar to parathyroid hormone (PTH), but C-terminal regions of the peptide, such as the 107–139 fragment found to inhibit resorption in a study by Fenton et al (1991), may have other biological activities not shared with PTH. We have compared the effects of the longer forms of recombinant human PTHrP (h PTHrP 1–84, 1–108, and 1–141) with hPTHrP 1–34 and synthetic bovine PTH (bPTH) 1–34 on bone resorption and formation in cultured neonatal mouse calvariae and fetal rat long bones. hPTHrP 1–84, 1–108, and 1–141 were qualitatively similar to hPTHrP 1–34 and PTH 1–34 in stimulating 45Ca release from both neonatal mouse calvariae and fetal rat long bones and in inhibiting the incorporation of [ 3H]-proline into collagenase digestible protein (CDP) and stimulating the incorporation of [ 3H]thymidine ( 3H-TdR) in neonatal mouse calvariae. However, hPTHrP 1–108 and 1–141 were less potent at stimulating 45Ca release and inhibiting CDP labeling than hPTHrP 1–34, while hPTHrP 1–84 showed an intermediate potency. Since hPTHrP 1–108 and 1–141 were quite similar in potency, the difference cannot be attributed to an inhibitory effect of the 107–139 fragment. All the peptide lengths tested showed similar potency in stimulating [ 3H]-TdR incorporation. These results suggest that different secreted forms of PTHrP are likely to have qualitatively similar effects on bone metabolism as long as the first 34 amino acids are present.